\lyxformat 221
\textclass book
\begin_preamble
+\pdfoptionpdfminorversion=3
\usepackage[
pdftitle={SDCC Compiler User Guide},
pdfauthor={SDCC development team},
pdfsubject={installation, user manual},
- pdfkeywords={8032, 8051, ansi, c, compiler, CPU, DS390,
- embedded, GPL, HC08, manual, mcs51, PIC, Z80},
+ pdfkeywords={8032 8051 ansi c compiler CPU DS390
+ embedded GPL HC08 manual mcs51 microcontroller PIC Z80},
colorlinks=true,
linkcolor=blue] {hyperref}
+%
+\sloppy
+\tolerance=500
+\emergencystretch=30pt
+%
\date{}
\end_preamble
\language english
\layout Comment
Architecture specific stuff (like memory models, code examples) should maybe
- go
+ later go
\layout Comment
into seperate sections/chapters/appendices (it is hard to document PIC or
Z80 in
\layout Comment
-a 8051 centered document)
+a 8051 centered document) - for now simply add.
\layout Title
SDCC Compiler User Guide
\layout Date
+\size normal
+SDCC 2.5.5
\size footnotesize
+
+\newline
$Date$
\newline
$Revision$
\layout Comment
-The above strings enclosed in $ are automatically updated by cvs
+The above strings enclosed in $ are automatically updated by Subversion
\layout Standard
\series bold
SDCC
\series default
- is a Freeware, retargettable, optimizing ANSI-C compiler by
+ (
+\emph on
+S
+\emph default
+mall
+\emph on
+D
+\emph default
+evice
+\emph on
+C
+\emph default
+
+\emph on
+C
+\emph default
+ompiler) is an open source, retargettable, optimizing ANSI-C compiler by
+
\series bold
Sandeep Dutta
\series default
\end_inset
-, etc.), Dallas DS80C390 variants, Motorola HC08 and Zilog Z80 based MCUs.
+, etc.), Dallas DS80C390 variants, Freescale (formerly Motorola) HC08 and
+ Zilog Z80 based MCUs.
It can be retargetted for other microprocessors, support for Microchip
PIC, Atmel AVR is under development.
The entire source code for the compiler is distributed under GPL.
- SDCC uses ASXXXX & ASLINK, a Freeware, retargettable assembler & linker.
+ SDCC uses ASXXXX
+\begin_inset LatexCommand \index{asXXXX (as-gbz80, as-hc08, asx8051, as-z80)}
+
+\end_inset
+
+ & ASLINK
+\begin_inset LatexCommand \index{aslink}
+
+\end_inset
+
+, an open source retargettable assembler & linker.
SDCC has extensive language extensions suitable for utilizing various microcont
rollers and underlying hardware effectively.
\newline
SDCC also comes with a companion source level debugger SDCDB, the debugger
currently uses ucSim a freeware simulator for 8051 and other micro-controllers.
+ SDCDB and ucSim are currently not available on Win32 platforms.
\newline
All packages used in this compiler system are
\emph on
-opensource
+open source
\emph default
and
\emph on
\layout Section
Compatibility with previous versions
+\begin_inset LatexCommand \index{Compatibility with previous versions}
+
+\end_inset
+
+
\layout Standard
This version has numerous bug fixes compared with the previous version.
\layout Itemize
short is now equivalent to int (16 bits), it used to be equivalent to char
- (8 bits) which is not ANSI compliant
+ (8 bits) which is not ANSI compliant.
\layout Itemize
the default directory for gcc-builds where include, library and documentation
- files are stored is now in /usr/local/share
+ files are stored is now in /usr/local/share.
\layout Itemize
char type parameters to vararg functions are casted to int unless explicitly
/
\end_inset
--regextend has been removed
+-regextend has been removed.
\layout Itemize
option -
/
\end_inset
--noregparms has been removed
+-noregparms has been removed.
\layout Itemize
option -
/
\end_inset
--stack-after-data has been removed
+-stack-after-data has been removed.
+\layout Itemize
+
+bit
+\begin_inset LatexCommand \index{bit}
+
+\end_inset
+
+ and sbit
+\begin_inset LatexCommand \index{sbit}
+
+\end_inset
+
+
+\begin_inset LatexCommand \index{\_\_sbit}
+
+\end_inset
+
+ types now consistently behave like the C99 _Bool type with respect to type
+ conversion
+\begin_inset LatexCommand \index{type conversion}
+
+\end_inset
+
+
+\begin_inset LatexCommand \index{type promotion}
+
+\end_inset
+
+.
+ The most common incompatibility resulting from this change is related to
+ bit toggling
+\begin_inset LatexCommand \index{Bit toggling}
+
+\end_inset
+
+ idioms, e.g.:
+\newline
+
+\family typewriter
+\SpecialChar ~
+\SpecialChar ~
+bit b;
+\newline
+\SpecialChar ~
+\SpecialChar ~
+b = ~b; /* equivalent to b=1 instead of toggling b */
+\newline
+\SpecialChar ~
+\SpecialChar ~
+b = !b; /* toggles b */
+\newline
+
+\family default
+In previous versions, both forms would have toggled the bit.
\layout Standard
Web links to other SDCC related sites can also be found here.
This document can be found in the DOC directory of the source package as
a text or HTML file.
+ A pdf version of this document is available at
+\begin_inset LatexCommand \url{http://sdcc.sourceforge.net/doc/sdccman.pdf}
+
+\end_inset
+
+.
Some of the other tools (simulator and assembler) included with SDCC contain
their own documentation and can be found in the source distribution.
If you want the latest unreleased software, the complete source package
- is available directly by anonymous CVS on cvs.sdcc.sourceforge.net.
+ is available directly from Subversion on https://svn.sourceforge.net/svnroot/sdcc
+/trunk/sdcc.
\layout Section
Wishes for the future
\family typewriter
-code banking
-\begin_inset LatexCommand \index{code banking (not supported)}
+better code banking
+\begin_inset LatexCommand \index{code banking (limited support)}
\end_inset
\newline
\family default
-If you can think of some more, please see the chapter
+If you can think of some more, please see the section
\begin_inset LatexCommand \ref{sub:Requesting-Features}
\end_inset
\layout Standard
Of course this doesn't change the search paths compiled into the binaries.
+\newline
+
+\newline
+Moreover the install path can be changed by defining DESTDIR
+\begin_inset LatexCommand \index{DESTDIR}
+
+\end_inset
+
+:
+\layout LyX-Code
+
+make install DESTDIR=$(HOME)/sdcc.rpm/
+\layout Standard
+
+Please note that DESTDIR must have a trailing slash!
\layout Section
Search Paths
\series medium
Download the source package
\series default
- either from the SDCC CVS repository or from the
-\begin_inset LatexCommand \url[nightly snapshots]{http://sdcc.sourceforge.net/snap.php}
-
-\end_inset
-
-
+ either from the SDCC Subversion repository or from the nightly snapshots
\series medium
, it will be named something like sdcc
\series default
\series default
ar.
\series medium
-gz.
+gz
+\series default
+
+\begin_inset LatexCommand \url{http://sdcc.sourceforge.net/snap.php}
+
+\end_inset
+
+.
\layout Enumerate
\series default
This copies the binary executables, the include files, the libraries and
the documentation to the install directories.
+ Proceed with section
+\begin_inset LatexCommand \ref{sec:Testing-the-SDCC}
+
+\end_inset
+
+.
\layout Subsection
Building SDCC on OSX 2.x
later
\layout Itemize
-cvs ; only if you use CVS access
+svn ; only if you use Subversion access
\layout Standard
If you want to develop something you'll need:
in binary mode.
And use an editor which can handle LF-only line endings.
Make sure not to commit files with windows line endings.
- The tabulator spacing used in the project is 8.
+ The tabulator spacing
+\begin_inset LatexCommand \index{tabulator spacing (8 columns)}
+
+\end_inset
+
+ used in the project is 8.
+ Although a tabulator spacing of 8 is a sensible choice for programmers
+ (it's a power of 2 and allows to display 8/16 bit signed variables without
+ loosing columns) the plan is to move towards using only spaces in the source.
\layout Subsection
Building SDCC Using Microsoft Visual C++ 6.0/NET (MSVC)
\series medium
Download the source package
\series default
- either from the SDCC CVS repository or from the
+ either from the SDCC Subversion repository or from the
\begin_inset LatexCommand \url[nightly snapshots]{http://sdcc.sourceforge.net/snap.php}
\end_inset
\newline
+\newline
+WARNING: Visual studio is very picky with line terminations; it expects
+ the 0x0d, 0x0a DOS style line endings, not the 0x0a Unix style line endings.
+ When using the Subversion repository it's easiest to configure the svn
+ client to convert automatically for you.
+ If however you are getting a message such as "This makefile was not generated
+ by Developer Studio etc.
+ etc.
+\begin_inset Quotes srd
+\end_inset
+
+ when opening the sdcc.dsw workspace or any of the *.dsp projects, then you
+ need to convert the Unix style line endings to DOS style line endings.
+ To do so you can use the
+\begin_inset Quotes sld
+\end_inset
+
+unix2dos
+\begin_inset Quotes srd
+\end_inset
+
+ utility freely available on the internet.
+ Doug Hawkins reported in the sdcc-user list that this works:
+\newline
+
+\newline
+C:
+\backslash
+Programming
+\backslash
+SDCC> unix2dos sdcc.dsw
+\newline
+C:
+\backslash
+Programming
+\backslash
+SDCC> for /R %I in (*.dsp) do @unix2dos "%I"
+\newline
+
\newline
In order to build SDCC with MSVC you need win32 executables of bison.exe,
flex.exe, and gawk.exe.
from the sdcc directory.
\layout Subsection
-Windows Install Using a Binary Package
-\begin_inset LatexCommand \label{sub:Windows-Install}
-
-\end_inset
-
-
+Windows Install Using a ZIP Package
\layout Enumerate
-Download the binary package from
-\begin_inset LatexCommand \url{http://sdcc.sourceforge.net/snap.php}
+Download the binary zip package from
+\begin_inset LatexCommand \url{http://sdcc.sf.net/snap.php}
\end_inset
Adjust your environment variable PATH to include the location of the bin
directory or start sdcc using the full path.
+\layout Subsection
+
+Windows Install Using the Setup Program
+\begin_inset LatexCommand \label{sub:Windows-Install}
+
+\end_inset
+
+
+\layout Standard
+
+Download the setup program
+\emph on
+sdcc-x.y.z-setup.exe
+\emph default
+ for an official release from
+\newline
+
+\begin_inset LatexCommand \url{http://sf.net/project/showfiles.php?group_id=599}
+
+\end_inset
+
+ or a setup program for one of the snapshots
+\emph on
+sdcc_yyyymmdd_setup.exe
+\emph default
+ from
+\begin_inset LatexCommand \url{http://sdcc.sf.net/snap.php}
+
+\end_inset
+
+ and execute it.
+ A windows typical installer will guide you through the installation process.
\layout Section
Building the Documentation
\layout Standard
-If the necessary tools (LyX, LaTeX, latex2html) are installed it is as easy
+If the necessary tools (LyX, LaTeX, LaTeX2HTML) are installed it is as easy
as changing into the doc directory and typing
\family sans
\series bold
\family default
\series default
there.
- If you want to avoid installing the tools you will have some success with
- a bootable Knoppix CD
-\begin_inset LatexCommand \url{http://www.knoppix.net}
+ You're invited to make changes and additions to this manual (sdcc/doc/sdccman.ly
+x).
+ Using LyX
+\begin_inset LatexCommand \url{http://www.lyx.org}
\end_inset
-.
+ as editor this is straightforward.
Prebuilt documentation in html and pdf format is available from
-\begin_inset LatexCommand \url{http://sdcc.sourceforge.net/snap.php}
+\begin_inset LatexCommand \url{http://sdcc.sf.net/snap.php}
\end_inset
Currently reading the document in pdf format is recommended, as for unknown
reason the hyperlinks are working there whereas in the html version they
- are not.
+ are not
+\begin_inset Foot
+collapsed false
+
+\layout Standard
+
+If you should know why please drop us a note
+\end_inset
+
+.
+
+\newline
+You'll find the pdf version
+\begin_inset LatexCommand \index{PDF version of this document}
+
+\end_inset
+
+ at
+\begin_inset LatexCommand \url{http://sdcc.sf.net/doc/sdccman.pdf}
+
+\end_inset
+
+.
+
+\newline
+A html version
+\begin_inset LatexCommand \index{HTML version of this document}
+
+\end_inset
+
+ should be online at
+\begin_inset LatexCommand \url{http://sdcc.sf.net/doc/sdccman.html/index.html}
+
+\end_inset
+
+.
\newline
This documentation is in some aspects different from a commercial documentation:
currently matches SDCC for mcs51 and DS390 best and does give too few informati
on about f.e.
- Z80, PIC and HC08.
+ Z80, PIC14, PIC16 and HC08.
\layout Itemize
There are many references pointing away from this documentation.
Don't let this distract you.
If there f.e.
was a reference like
-\begin_inset LatexCommand \url{www.opencores.org}
+\begin_inset LatexCommand \url{http://www.opencores.org}
\end_inset
a
\emph default
rray
-\begin_inset LatexCommand \index{fpga (field programmable gate array)}
+\begin_inset LatexCommand \index{FPGA (field programmable gate array)}
+
+\end_inset
+
+
+\begin_inset Quotes srd
+\end_inset
+
+ or
+\begin_inset LatexCommand \url{http://sf.net/projects/fpgac}
+
+\end_inset
+
+
+\begin_inset LatexCommand \index{FpgaC ((subset of) C to FPGA compiler)}
\end_inset
+
+\begin_inset Quotes sld
+\end_inset
+have you ever heard of an open source compiler that compiles a subset of
+ C for an FPGA?
\begin_inset Quotes srd
\end_inset
\layout Section
Testing the SDCC Compiler
+\begin_inset LatexCommand \label{sec:Testing-the-SDCC}
+
+\end_inset
+
+
\layout Standard
The first thing you should do after installing your SDCC compiler is to
\begin_inset Quotes srd
\end_inset
-
+.
\newline
\newline
\layout Subsection
-SDCC does not build correctly.
+If SDCC does not build correctly
\layout Standard
A thing to try is starting from scratch by unpacking the .tgz source package
\begin_inset Quotes srd
\end_inset
- does.
+ does
\layout Standard
This runs the GNU make tool, which automatically compiles all the source
\layout Itemize
s51 - The ucSim 8051 simulator.
+ Not available on Win32 platforms.
\layout Itemize
sdcdb - The source debugger.
+ Not available on Win32 platforms.
\layout Itemize
packihx - A tool to pack (compress) Intel hex files.
the assembler and linkage editor.
\layout Subsection
-sdcpp
-\begin_inset LatexCommand \index{sdcpp}
+sdcpp - The C-Preprocessor
+\layout Standard
-\end_inset
+The preprocessor
+\begin_inset LatexCommand \index{sdcpp (preprocessor)}
- - The C-Preprocessor
-\layout Standard
+\end_inset
-The preprocessor is a modified version of the GNU preprocessor.
+ is a modified version of the GNU preprocessor.
The C preprocessor is used to pull in #include sources, process #ifdef
statements, #defines and so on.
\layout Subsection
-asx8051, as-z80, as-gbz80, aslink, link-z80, link-gbz80 - The Assemblers
- and Linkage Editors
+as
+\emph on
+xxxx
+\emph default
+, aslink, link-
+\emph on
+xxx
+\emph default
+ - The Assemblers and Linkage Editors
\layout Standard
This is retargettable assembler & linkage editor, it was developed by Alan
\layout Subsection
s51 - The Simulator
-\begin_inset LatexCommand \index{s51}
-
-\end_inset
-
-
\layout Standard
-S51 is a freeware, opensource simulator developed by Daniel Drotos (
-\begin_inset LatexCommand \url{mailto:drdani@mazsola.iit.uni-miskolc.hu}
+S51
+\begin_inset LatexCommand \index{s51}
\end_inset
-).
+ is a freeware, opensource simulator developed by Daniel Drotos.
The simulator is built as part of the build process.
For more information visit Daniel's web site at:
\begin_inset LatexCommand \url{http://mazsola.iit.uni-miskolc.hu/~drdani/embedded/s51}
.
It currently supports the core mcs51, the Dallas DS80C390 and the Phillips
XA51 family.
+ S51 is currently not available on Win32 platfors.
\layout Subsection
-sdcdb
-\begin_inset LatexCommand \index{sdcdb}
+sdcdb - Source Level Debugger
+\layout Standard
+
+Sdcdb
+\begin_inset LatexCommand \index{sdcdb (debugger)}
\end_inset
- - Source Level Debugger
-\layout Standard
+ is the companion source level debugger.
+ More about sdcdb in section
+\begin_inset LatexCommand \ref{cha:Debugging-with-SDCDB}
+
+\end_inset
-Sdcdb is the companion source level debugger.
+.
The current version of the debugger uses Daniel's Simulator S51
\begin_inset LatexCommand \index{s51}
\end_inset
, but can be easily changed to use other simulators.
+ Sdcdb is currently not available on Win32 platfors.
\layout Chapter
Using SDCC
\family default
\series default
This will compile, assemble and link your source file.
- Output files are as follows
+ Output files are as follows:
\layout Itemize
sourcefile.asm
sourcefile.rel
\begin_inset LatexCommand \index{<file>.rel}
+\end_inset
+
+ or sourcefile.o
+\begin_inset LatexCommand \index{<file>.o}
+
\end_inset
- Object file
\family default
\shape default
-\begin_inset LatexCommand \index{objdump}
+\begin_inset LatexCommand \index{objdump (tool)}
\end_inset
\family default
\shape default
-\begin_inset LatexCommand \index{srecord}
+\begin_inset LatexCommand \index{srecord (bin, hex, ... tool)}
\end_inset
-)
+).
+ Both formats are documented in the documentation of srecord
+\begin_inset LatexCommand \index{srecord (bin, hex, ... tool)}
+
+\end_inset
+
+
\layout Itemize
sourcefile.adb
-\begin_inset LatexCommand \index{.adb}
+\begin_inset LatexCommand \index{<file>.adb}
\end_inset
- An intermediate file containing debug information needed to create the
.cdb file (with -
\begin_inset ERT
-status Collapsed
+status Open
\layout Standard
/
\end_inset
--debug) containing debug information
+-debug) containing debug information.
+ The format is documented in cdbfileformat.pdf
\layout Itemize
sourcefile.
\end_inset
- An optional AOMF51
-\begin_inset LatexCommand \index{AOMF51}
+ An optional AOMF or AOMF51
+\begin_inset LatexCommand \index{AOMF, AOMF51}
\end_inset
- file containing debug information (with -
+ file containing debug information (generated with option -
\begin_inset ERT
status Collapsed
\end_inset
-debug).
- This format is commonly used by third party tools (debuggers
+ The (Intel)
+\emph on
+ a
+\emph default
+bsolute
+\emph on
+o
+\emph default
+bject
+\emph on
+m
+\emph default
+odule
+\emph on
+f
+\emph default
+ormat is commonly used by third party tools (debuggers
\begin_inset LatexCommand \index{Debugger}
\end_inset
\end_inset
- - Dump file to debug the compiler it self (with -
+ - Dump file to debug the compiler it self (generated with option -
\begin_inset ERT
status Collapsed
\family default
\series default
-\begin_inset LatexCommand \index{.rel}
+\begin_inset LatexCommand \index{<file>.rel}
\end_inset
file specified in the command line, since the linkage editor processes
file in the order they are presented to it.
The linker is invoked from SDCC using a script file with extension .lnk
-\begin_inset LatexCommand \index{.lnk}
+\begin_inset LatexCommand \index{<file>.lnk}
\end_inset
for how to create a
\emph on
.lib
-\begin_inset LatexCommand \index{.lib}
+\begin_inset LatexCommand \index{<file>.lib}
\end_inset
The most efficient way to use libraries is to keep separate modules in separate
source files.
The lib file now should name all the modules.rel
-\begin_inset LatexCommand \index{rel}
+\begin_inset LatexCommand \index{<file>.rel}
\end_inset
libsdcc.lib
\emph default
in the directory <installdir>/share/lib/small.
-\layout Section
+\layout Subsection
-Command Line Options
-\begin_inset LatexCommand \index{Command Line Options}
+Using sdcclib to Create and Manage Libraries
+\begin_inset LatexCommand \index{sdcclib}
\end_inset
-\layout Subsection
+\layout Standard
-Processor Selection Options
-\begin_inset LatexCommand \index{Options processor selection}
+Alternatively, instead of having a .rel file for each entry on the library
+ file as described in the preceding section, sdcclib can be used to embed
+ all the modules belonging to such library in the library file itself.
+ This results in a larger library file, but it greatly reduces the number
+ of disk files accessed by the linker.
+ Additionally, the packed library file contains an index of all include
+ modules and symbols that significantly speeds up the linking process.
+ To display a list of options supported by sdcclib type:
+\newline
-\end_inset
+\layout Standard
-\begin_inset LatexCommand \index{Processor selection options}
+\family sans
+\series bold
+sdcclib -?
+\begin_inset LatexCommand \index{sdcclib}
\end_inset
-\layout List
-\labelwidthstring 00.00.0000
+\newline
+
+\newline
+
+\family default
+\series default
+To create a new library file, start by compiling all the required modules.
+ For example:
+\newline
+
+\layout Standard
+
+
+\family sans
+\series bold
+sdcc -c _divsint.c
+\layout Standard
+
+
+\family sans
+\series bold
+sdcc -c _divuint.c
+\layout Standard
+
+
+\family sans
+\series bold
+sdcc -c _modsint.c
+\layout Standard
+
+
+\family sans
+\series bold
+sdcc -c _moduint.c
+\layout Standard
+
+
+\family sans
+\series bold
+sdcc -c _mulint.c
+\newline
+
+\layout Standard
+
+This will create files _divsint.rel, _divuint.rel, _modsint.rel, _moduint.rel,
+ and _mulint.rel.
+ The next step is to add the .rel files to the library file:
+\newline
+
+\layout Standard
+
+
+\family sans
+\series bold
+sdcclib libint.lib _divsint.rel
+\family default
+
+\begin_inset LatexCommand \index{sdcclib}
+
+\end_inset
+
+
+\layout Standard
+
+
+\family sans
+\series bold
+sdcclib libint.lib _divuint.rel
+\layout Standard
+
+
+\family sans
+\series bold
+sdcclib libint.lib _modsint.rel
+\layout Standard
+
+
+\family sans
+\series bold
+sdcclib libint.lib _moduint.rel
+\layout Standard
+
+
+\family sans
+\series bold
+sdcclib libint.lib _mulint.rel
+\series default
+
+\newline
+
+\layout Standard
+
+If the file already exists in the library, it will be replaced.
+ To see what modules and symbols are included in the library, options -s
+ and -m are available.
+ For example:
+\newline
+
+\newline
+
+\family sans
+\series bold
+sdcclib -s libint.lib
+\family default
+
+\begin_inset LatexCommand \index{sdcclib}
+
+\end_inset
+
+
+\newline
+
+\family typewriter
+\series default
+_divsint.rel:
+\layout Standard
+
+
+\family typewriter
+__divsint_a_1_1
+\layout Standard
+
+
+\family typewriter
+__divsint_PARM_2
+\layout Standard
+
+
+\family typewriter
+__divsint
+\newline
+_divuint.rel:
+\layout Standard
+
+
+\family typewriter
+__divuint_a_1_1
+\layout Standard
+
+
+\family typewriter
+__divuint_PARM_2
+\layout Standard
+
+
+\family typewriter
+__divuint_reste_1_1
+\layout Standard
+
+
+\family typewriter
+__divuint_count_1_1
+\layout Standard
+
+
+\family typewriter
+__divuint
+\newline
+_modsint.rel:
+\layout Standard
+
+
+\family typewriter
+__modsint_a_1_1
+\layout Standard
+
+
+\family typewriter
+__modsint_PARM_2
+\layout Standard
+
+
+\family typewriter
+__modsint
+\newline
+_moduint.rel:
+\layout Standard
+
+
+\family typewriter
+__moduint_a_1_1
+\layout Standard
+
+
+\family typewriter
+__moduint_PARM_2
+\layout Standard
+
+
+\family typewriter
+__moduint_count_1_1
+\layout Standard
+
+
+\family typewriter
+__moduint
+\newline
+_mulint.rel:
+\layout Standard
+
+
+\family typewriter
+__mulint_PARM_2
+\layout Standard
+
+
+\family typewriter
+__mulint
+\family default
+\series bold
+
+\newline
+
+\layout Standard
+
+If the source files are compiled using -
+\begin_inset ERT
+status Open
+
+\layout Standard
+
+\backslash
+/
+\end_inset
+
+-debug
+\begin_inset LatexCommand \index{-\/-debug}
+
+\end_inset
+
+, the corresponding debug information file .adb will be include in the library
+ file as well.
+ The library files created with sdcclib are plain text files, so they can
+ be viewed with a text editor.
+ It is not recomended to modify a library file created with sdcclib using
+ a text editor, as there are file indexes numbers located accross the file
+ used by the linker to quickly locate the required module to link.
+ Once a .rel file (as well as a .adb file) is added to a library using sdcclib,
+ it can be safely deleted, since all the information required for linking
+ is embedded in the library file itself.
+ Library files created using sdcclib are used as described in the preceding
+ sections.
+\layout Section
+
+Command Line Options
+\begin_inset LatexCommand \index{Command Line Options}
+
+\end_inset
+
+
+\layout Subsection
+
+Processor Selection Options
+\begin_inset LatexCommand \index{Options processor selection}
+
+\end_inset
+
+
+\begin_inset LatexCommand \index{Processor selection options}
+
+\end_inset
+
+
+\layout List
+\labelwidthstring 00.00.0000
\series bold
\series default
- Generate code for the Motorola HC08
+ Generate code for the Freescale/Motorola HC08
\begin_inset LatexCommand \index{HC08}
\end_inset
- family of processors (added Oct 2003).
+ family of processors.
\layout List
\labelwidthstring 00.00.0000
\end_inset
- processor.
+ processor (Not actively maintained).
\layout List
\labelwidthstring 00.00.0000
\end_inset
processor (In development, not complete).
- AVR users should probably have a look at avr-gcc
-\begin_inset LatexCommand \url{ http://savannah.nongnu.org/download/avr-libc/snapshots/}
+ AVR users should probably have a look at winavr
+\begin_inset LatexCommand \url{http://sourceforge.net/projects/winavr}
+
+\end_inset
+
+ or
+\begin_inset LatexCommand \url{http://www.avrfreaks.net/index.php?name=PNphpBB2&file=index}
\end_inset
\end_inset
--bit processors (p16f84 and variants).
+-bit processors (p16f84 and variants.
+ In development, not complete).
\layout Comment
p16f627 p16f628 p16f84 p16f873 p16f877?
\end_inset
--bit processors (p18f452 and variants).
+-bit processors (p18f452 and variants.
+ In development, not complete).
\layout List
\labelwidthstring 00.00.0000
\end_inset
- processor (In development, not complete).
+ processor (Not maintained, not complete).
\layout List
\labelwidthstring 00.00.0000
\end_inset
- processor (In development, not complete).
+ processor (Not maintained, not complete).
\layout Subsection
Preprocessor Options
\end_inset
+\begin_inset LatexCommand \index{sdcpp (preprocessor)}
+
+\end_inset
+
+
\layout List
\labelwidthstring 00.00.0000
\end_inset
...
- Pass the preprocessorOption to the preprocessor.
+ Pass the preprocessorOption to the preprocessor
+\family typewriter
+sdcpp
+\family default
+
+\begin_inset LatexCommand \index{sdcpp (preprocessor)}
+
+\end_inset
+
+.
+ SDCC uses an adapted version of the preprocessor cpp of the GNU Compiler
+ Collection (gcc), if you need more dedicated options please refer to the
+ documentation at
+\begin_inset LatexCommand \htmlurl{http://www.gnu.org/software/gcc/onlinedocs/}
+
+\end_inset
+
+.
\layout Subsection
Linker Options
\SpecialChar ~
<Value> The start location of the external ram
-\begin_inset LatexCommand \index{xdata}
+\begin_inset LatexCommand \index{xdata (mcs51, ds390 storage class)}
\end_inset
The provided value should not overlap any other memory areas such as used
register banks or the data segment and with enough space for the current
application.
-\layout List
-\labelwidthstring 00.00.0000
-
-
+ The
\series bold
-
\begin_inset ERT
/
\end_inset
--data-loc
+-pack-iram
\series default
-
-\begin_inset LatexCommand \index{-\/-data-loc <Value>}
-
-\end_inset
-
\SpecialChar ~
-<Value> The start location of the internal ram data
-\begin_inset LatexCommand \index{data}
+
+\begin_inset LatexCommand \index{-\/-pack-iram}
\end_inset
- segment.
- The value entered can be in Hexadecimal or Decimal format, eg.
- -
+ option (which is now a default setting) will override this setting, so
+ you should also specify the
+\series bold
+-
\begin_inset ERT
status Collapsed
/
\end_inset
--data-loc 0x20 or -
-\begin_inset ERT
-status Collapsed
+-no-pack-iram
+\series default
+\SpecialChar ~
-\layout Standard
+\begin_inset LatexCommand \index{-\/-no-pack-iram}
-\backslash
-/
\end_inset
--data-loc 32.
- (By default, the start location of the internal ram data segment is set
+ option if you need to manually place the stack.
+\layout List
+\labelwidthstring 00.00.0000
+
+
+\series bold
+-
+\begin_inset ERT
+status Collapsed
+
+\layout Standard
+
+\backslash
+/
+\end_inset
+
+-xstack-loc
+\series default
+
+\begin_inset LatexCommand \index{-\/-xstack-loc <Value>}
+
+\end_inset
+
+\SpecialChar ~
+<Value> By default the external stack
+\begin_inset LatexCommand \index{xstack}
+
+\end_inset
+
+ is placed after the pdata segment.
+ Using this option the xstack can be placed anywhere in the external memory
+ space of the 8051.
+ The value entered can be in Hexadecimal or Decimal format, e.g.
+ -
+\begin_inset ERT
+status Collapsed
+
+\layout Standard
+
+\backslash
+/
+\end_inset
+
+-xstack-loc 0x8000 or -
+\begin_inset ERT
+status Collapsed
+
+\layout Standard
+
+\backslash
+/
+\end_inset
+
+-stack-loc 32768.
+ The provided value should not overlap any other memory areas such as the
+ pdata or xdata segment and with enough space for the current application.
+\layout List
+\labelwidthstring 00.00.0000
+
+
+\series bold
+-
+\begin_inset ERT
+status Collapsed
+
+\layout Standard
+
+\backslash
+/
+\end_inset
+
+-data-loc
+\series default
+
+\begin_inset LatexCommand \index{-\/-data-loc <Value>}
+
+\end_inset
+
+\SpecialChar ~
+<Value> The start location of the internal ram data
+\begin_inset LatexCommand \index{data (mcs51, ds390 storage class)}
+
+\end_inset
+
+ segment.
+ The value entered can be in Hexadecimal or Decimal format, eg.
+ -
+\begin_inset ERT
+status Collapsed
+
+\layout Standard
+
+\backslash
+/
+\end_inset
+
+-data-loc 0x20 or -
+\begin_inset ERT
+status Collapsed
+
+\layout Standard
+
+\backslash
+/
+\end_inset
+
+-data-loc 32.
+ (By default, the start location of the internal ram data segment is set
as low as possible in memory, taking into account the used register banks
and the bit segment at address 0x20.
For example if register banks 0 and 1 are used without bit variables, the
\SpecialChar ~
<Value> The start location of the indirectly addressable internal ram
-\begin_inset LatexCommand \index{idata}
+\begin_inset LatexCommand \index{idata (mcs51, ds390 storage class)}
\end_inset
\end_inset
- (This is the default option).
+ This is the default option.
+ The format itself is documented in the documentation of srecord
+\begin_inset LatexCommand \index{srecord (bin, hex, ... tool)}
+
+\end_inset
+
+.
\layout List
\labelwidthstring 00.00.0000
\end_inset
.
+ The format itself is documented in the documentation of srecord.
+\layout List
+\labelwidthstring 00.00.0000
+
+
+\series bold
+-
+\begin_inset ERT
+status Collapsed
+
+\layout Standard
+
+\backslash
+/
+\end_inset
+
+-out-fmt-elf
+\begin_inset LatexCommand \index{-\/-out-fmt-s19}
+
+\end_inset
+
+
+\bar under
+
+\series default
+\bar default
+The linker output (final object code) is in ELF format
+\begin_inset LatexCommand \index{ELF format}
+
+\end_inset
+
+.
+ (Currently only supported for the HC08 processors)
\layout List
\labelwidthstring 00.00.0000
...
Pass the linkOption to the linker.
+ See file sdcc/as/doc/asxhtm.html for more on linker options.
\layout Subsection
MCS51 Options
\size default
\emph default
-Generate code for Small Model programs see section Memory Models for more
+Generate code for Small Model programs, see section Memory Models for more
details.
This is the default model.
\layout List
\labelwidthstring 00.00.0000
+\series bold
+-
+\begin_inset ERT
+status Collapsed
+
+\layout Standard
+
+\backslash
+/
+\end_inset
+
+-model-medium
+\begin_inset LatexCommand \index{-\/-model-medium}
+
+\end_inset
+
+
+\series default
+ Generate code for Medium model programs, see section Memory Models for
+ more details.
+ If this option is used all source files in the project have to be compiled
+ with this option.
+ It must also be used when invoking the linker.
+\layout List
+\labelwidthstring 00.00.0000
+
+
\series bold
-
\begin_inset ERT
\series default
- Generate code for Large model programs see section Memory Models for more
+ Generate code for Large model programs, see section Memory Models for more
details.
If this option is used all source files in the project have to be compiled
with this option.
+ It must also be used when invoking the linker.
\layout List
\labelwidthstring 00.00.0000
Causes the linker to check if the code memory usage is within limits of
the given value.
+\layout List
+\labelwidthstring 00.00.0000
+
+
+\series bold
+-
+\begin_inset ERT
+status Collapsed
+
+\layout Standard
+
+\backslash
+/
+\end_inset
+
+-stack-size
+\series default
+\SpecialChar ~
+<Value>
+\begin_inset LatexCommand \index{-\/-stack-size <Value>}
+
+\end_inset
+
+ Causes the linker to check if there is at minimum <Value> bytes for stack.
+\layout List
+\labelwidthstring 00.00.0000
+
+
+\series bold
+-
+\begin_inset ERT
+status Collapsed
+
+\layout Standard
+
+\backslash
+/
+\end_inset
+
+-pack-iram
+\series default
+\SpecialChar ~
+
+\begin_inset LatexCommand \index{-\/-pack-iram}
+
+\end_inset
+
+ Causes the linker to use unused register banks for data variables and pack
+ data, idata and stack together.
+ This is the default now.
+\layout List
+\labelwidthstring 00.00.0000
+
+
+\series bold
+-
+\begin_inset ERT
+status Collapsed
+
+\layout Standard
+
+\backslash
+/
+\end_inset
+
+-no-pack-iram
+\series default
+\SpecialChar ~
+
+\begin_inset LatexCommand \index{-\/-no-pack-iram}
+
+\end_inset
+
+ Causes the linker to use old style for allocating memory areas.
\layout Subsection
-DS390 Options
+DS390 / DS400 Options
\begin_inset LatexCommand \index{Options DS390}
\end_inset
\labelwidthstring 00.00.0000
+\series bold
+-
+\begin_inset ERT
+status Collapsed
+
+\layout Standard
+
+\backslash
+/
+\end_inset
+
+-protect-sp-update
+\begin_inset LatexCommand \index{-\/-protect-sp-update}
+
+\end_inset
+
+
+\series default
+ disable interrupts during ESP:SP updates.
+\layout List
+\labelwidthstring 00.00.0000
+
+
\series bold
-
\begin_inset ERT
-model-flat24 option
\emph default
).
-\layout Subsection
+\layout List
+\labelwidthstring 00.00.0000
-Z80 Options
-\begin_inset LatexCommand \index{Options Z80}
-\end_inset
+\series bold
+-
+\begin_inset ERT
+status Collapsed
+\layout Standard
-\begin_inset LatexCommand \index{Z80 options}
+\backslash
+/
+\end_inset
+
+-stack-probe
+\begin_inset LatexCommand \index{-\/-stack-probe}
\end_inset
+\series default
+ insert call to function __stack_probe at each function prologue.
\layout List
\labelwidthstring 00.00.0000
/
\end_inset
--callee-saves-bc
-\series default
-
-\begin_inset LatexCommand \index{-\/-callee-saves-bc}
+-tini-libid
+\begin_inset LatexCommand \index{-\/-tini-libid}
\end_inset
-\size large
-\emph on
+\series default
+ <nnnn> LibraryID used in -mTININative.
+
+\layout List
+\labelwidthstring 00.00.0000
+
+
+\series bold
+-
+\begin_inset ERT
+status Collapsed
+
+\layout Standard
+
+\backslash
+/
+\end_inset
+
+-use-accelerator
+\begin_inset LatexCommand \index{-\/-use-accelerator}
+
+\end_inset
+
+
+\series default
+ generate code for DS390 Arithmetic Accelerator.
+
+\layout Subsection
+
+Z80 Options
+\begin_inset LatexCommand \index{Options Z80}
+
+\end_inset
+
+
+\begin_inset LatexCommand \index{Z80 options}
+
+\end_inset
+
+
+\layout List
+\labelwidthstring 00.00.0000
+
+
+\series bold
+-
+\begin_inset ERT
+status Collapsed
+
+\layout Standard
+
+\backslash
+/
+\end_inset
+
+-callee-saves-bc
+\series default
+
+\begin_inset LatexCommand \index{-\/-callee-saves-bc}
+
+\end_inset
+
+
+\size large
+\emph on
\size default
\emph default
\series default
Will not do global subexpression elimination, this option may be used when
the compiler creates undesirably large stack/data spaces to store compiler
- temporaries.
+ temporaries (
+\emph on
+s
+\emph default
+pill
+\emph on
+loc
+\emph default
+ations, sloc
+\begin_inset LatexCommand \index{sloc (spill location)}
+
+\end_inset
+
+).
A warning message will be generated when this happens and the compiler
will indicate the number of extra bytes it allocated.
- It recommended that this option NOT be used, #pragma\SpecialChar ~
-NOGCSE
-\begin_inset LatexCommand \index{\#pragma NOGCSE}
+ It is recommended that this option NOT be used, #pragma\SpecialChar ~
+nogcse
+\begin_inset LatexCommand \index{\#pragma nogcse}
\end_inset
\series default
Will not do loop invariant optimizations, this may be turned off for reasons
explained for the previous option.
- For more details of loop optimizations performed see section Loop Invariants.It
- recommended that this option NOT be used, #pragma\SpecialChar ~
-NOINVARIANT
-\begin_inset LatexCommand \index{\#pragma NOINVARIANT}
+ For more details of loop optimizations performed see Loop Invariants in
+ section
+\begin_inset LatexCommand \ref{sub:Loop-Optimizations}
+
+\end_inset
+
+.
+ It is recommended that this option NOT be used, #pragma\SpecialChar ~
+noinvariant
+\begin_inset LatexCommand \index{\#pragma noinvariant}
\end_inset
\series default
Will not do loop induction optimizations, see section strength reduction
- for more details.It is recommended that this option is NOT used, #pragma\SpecialChar ~
-NOINDUCT
-ION
-\begin_inset LatexCommand \index{\#pragma NOINDUCTION}
+ for more details.
+ It is recommended that this option is NOT used, #pragma\SpecialChar ~
+noinduction
+\begin_inset LatexCommand \index{\#pragma noinduction}
\end_inset
\SpecialChar ~
Switch Statements for more details.
It is recommended that this option is NOT used, #pragma\SpecialChar ~
-NOJTBOUND
-\begin_inset LatexCommand \index{\#pragma NOJTBOUND}
+nojtbound
+\begin_inset LatexCommand \index{\#pragma nojtbound}
\end_inset
\series default
Will not memcpy initialized data from code space into xdata space.
- This saves a few bytes in code space if you don't have initialized data.
+ This saves a few bytes in code space if you don't have initialized data
+\begin_inset LatexCommand \index{Variable initialization}
+
+\end_inset
+
+.
+\layout List
+\labelwidthstring 00.00.0000
+
+
+\series bold
+-
+\begin_inset ERT
+status Collapsed
+
+\layout Standard
+
+\backslash
+/
+\end_inset
+
+-nooverlay
+\begin_inset LatexCommand \index{-\/-nooverlay}
+
+\end_inset
+
+
+\series default
+ The compiler will not overlay parameters and local variables of any function,
+ see section Parameters and local variables for more details.
+\layout List
+\labelwidthstring 00.00.0000
+
+
+\series bold
+-
+\begin_inset ERT
+status Collapsed
+
+\layout Standard
+
+\backslash
+/
+\end_inset
+
+-no-peep
+\begin_inset LatexCommand \index{-\/-no-peep}
+
+\end_inset
+
+
+\series default
+ Disable peep-hole optimization.
+\layout List
+\labelwidthstring 00.00.0000
+
+
+\series bold
+-
+\begin_inset ERT
+status Collapsed
+
+\layout Standard
+
+\backslash
+/
+\end_inset
+
+-peep-file
+\series default
+
+\begin_inset LatexCommand \index{-\/-peep-file}
+
+\end_inset
+
+\SpecialChar ~
+<filename> This option can be used to use additional rules to be used by
+ the peep hole optimizer.
+ See section
+\begin_inset LatexCommand \ref{sub:Peephole-Optimizer}
+
+\end_inset
+
+\SpecialChar ~
+Peep Hole optimizations for details on how to write these rules.
+\layout List
+\labelwidthstring 00.00.0000
+
+
+\series bold
+-
+\begin_inset ERT
+status Collapsed
+
+\layout Standard
+
+\backslash
+/
+\end_inset
+
+-peep-asm
+\begin_inset LatexCommand \index{-\/-peep-asm}
+
+\end_inset
+
+
+\series default
+ Pass the inline assembler code through the peep hole optimizer.
+ This can cause unexpected changes to inline assembler code, please go through
+ the peephole optimizer
+\begin_inset LatexCommand \index{Peephole optimizer}
+
+\end_inset
+
+ rules defined in the source file tree '<target>/peeph.def' before using
+ this option.
+\layout List
+\labelwidthstring 00.00.0000
+
+
+\series bold
+-
+\begin_inset ERT
+status Collapsed
+
+\layout Standard
+
+\backslash
+/
+\end_inset
+
+-opt-code-speed
+\begin_inset LatexCommand \index{-\/-opt-code-speed}
+
+\end_inset
+
+
+\series default
+ The compiler will optimize code generation towards fast code, possibly
+ at the expense of code size.
+\layout List
+\labelwidthstring 00.00.0000
+
+
+\series bold
+-
+\begin_inset ERT
+status Collapsed
+
+\layout Standard
+
+\backslash
+/
+\end_inset
+
+-opt-code-size
+\begin_inset LatexCommand \index{-\/-opt-code-size}
+
+\end_inset
+
+
+\series default
+ The compiler will optimize code generation towards compact code, possibly
+ at the expense of code speed.
\layout Subsection
Other Options
\end_inset
.
- see section Parameters and Local Variables for more details.
+ See section
+\begin_inset LatexCommand \ref{sec:Parameters-and-Local-Variables}
+
+\end_inset
+
+ Parameters and Local Variables for more details.
If this option is used all source files in the project should be compiled
with this option.
+ It automatically implies --int-long-reent and --float-reent.
\layout List
\labelwidthstring 00.00.0000
-callee-saves option string.
Also see #pragma\SpecialChar ~
-CALLEE-SAVES
-\begin_inset LatexCommand \index{\#pragma CALLEE-SAVES}
+callee_saves
+\begin_inset LatexCommand \index{\#pragma callee\_saves}
\end_inset
\series default
\bar default
-When this option is used the compiler will generate debug information, that
- can be used with the SDCDB.
- The debug information is collected in a file with .cdb extension.
+When this option is used the compiler will generate debug information.
+ The debug information collected in a file with .cdb extension can be used
+ with the SDCDB.
For more information see documentation for SDCDB.
+ Another file with no extension contains debug information in AOMF or AOMF51
+\begin_inset LatexCommand \index{AOMF, AOMF51}
+
+\end_inset
+
+ format which is commonly used by third party tools.
\layout List
\labelwidthstring 00.00.0000
\end_inset
-\bar under
-
\series default
-\bar default
Floating point library is compiled as reentrant
\begin_inset LatexCommand \index{reentrant}
/
\end_inset
--nooverlay
-\begin_inset LatexCommand \index{-\/-nooverlay}
+-main-return
+\begin_inset LatexCommand \index{-\/-main-return}
\end_inset
\series default
- The compiler will not overlay parameters and local variables of any function,
- see section Parameters and local variables for more details.
+ This option can be used if the code generated is called by a monitor program
+ or if the main routine includes an endless loop.
+ This option might result in slightly smaller code and save two bytes of
+ stack space.
+ The return from the 'main'
+\begin_inset LatexCommand \index{main return}
+
+\end_inset
+
+ function will return to the function calling main.
+ The default setting is to lock up i.e.
+ generate a '
+\family typewriter
+sjmp .
+\family default
+'.
\layout List
\labelwidthstring 00.00.0000
/
\end_inset
--main-return
-\begin_inset LatexCommand \index{-\/-main-return}
+-nostdinc
+\begin_inset LatexCommand \index{-\/-nostdinc}
\end_inset
\series default
- This option can be used when the code generated is called by a monitor
- program.
- The compiler will generate a 'ret' upon return from the 'main'
-\begin_inset LatexCommand \index{main return}
-
-\end_inset
-
- function.
- The default setting is to lock up i.e.
- generate a '
-\family typewriter
-ljmp .
-\family default
-'.
+ This will prevent the compiler from passing on the default include path
+ to the preprocessor.
\layout List
\labelwidthstring 00.00.0000
/
\end_inset
--peep-file
-\series default
-
-\begin_inset LatexCommand \index{-\/-peep-file}
+-nostdlib
+\begin_inset LatexCommand \index{-\/-nostdlib}
\end_inset
-\SpecialChar ~
-<filename> This option can be used to use additional rules to be used by
- the peep hole optimizer.
- See section
-\begin_inset LatexCommand \ref{sub:Peephole-Optimizer}
+
+\series default
+ This will prevent the compiler from passing on the default library
+\begin_inset LatexCommand \index{Libraries}
\end_inset
-\SpecialChar ~
-Peep Hole optimizations for details on how to write these rules.
+ path to the linker.
\layout List
\labelwidthstring 00.00.0000
/
\end_inset
--no-peep
-\begin_inset LatexCommand \index{-\/-no-peep}
+-verbose
+\begin_inset LatexCommand \index{-\/-verbose}
\end_inset
\series default
- Disable peep-hole optimization.
+ Shows the various actions the compiler is performing.
\layout List
\labelwidthstring 00.00.0000
\series bold
--
-\begin_inset ERT
-status Collapsed
-
-\layout Standard
-
-\backslash
-/
-\end_inset
-
--peep-asm
-\begin_inset LatexCommand \index{-\/-peep-asm}
+-V
+\begin_inset LatexCommand \index{-V}
\end_inset
\series default
- Pass the inline assembler code through the peep hole optimizer.
- This can cause unexpected changes to inline assembler code, please go through
- the peephole optimizer
-\begin_inset LatexCommand \index{Peephole optimizer}
-
-\end_inset
-
- rules defined in the source file tree '<target>/peeph.def' before using
- this option.
+ Shows the actual commands the compiler is executing.
\layout List
\labelwidthstring 00.00.0000
/
\end_inset
--nostdincl
-\begin_inset LatexCommand \index{-\/-nostdincl}
+-no-c-code-in-asm
+\begin_inset LatexCommand \index{-\/-no-c-code-in-asm}
\end_inset
\series default
- This will prevent the compiler from passing on the default include path
- to the preprocessor.
+ Hides your ugly and inefficient c-code from the asm file, so you can always
+ blame the compiler :)
\layout List
\labelwidthstring 00.00.0000
/
\end_inset
--nostdlib
-\begin_inset LatexCommand \index{-\/-nostdlib}
+-no-peep-comments
+\begin_inset LatexCommand \index{-\/-no-peep-comments}
\end_inset
\series default
- This will prevent the compiler from passing on the default library
-\begin_inset LatexCommand \index{Libraries}
-
-\end_inset
-
- path to the linker.
+ Will not include peep-hole comments in the generated files.
\layout List
\labelwidthstring 00.00.0000
/
\end_inset
--verbose
-\begin_inset LatexCommand \index{-\/-verbose}
-
-\end_inset
-
-
-\series default
- Shows the various actions the compiler is performing.
-\layout List
-\labelwidthstring 00.00.0000
-
-
-\series bold
--V
-\begin_inset LatexCommand \index{-V}
+-i-code-in-asm
+\begin_inset LatexCommand \index{-\/-i-code-in-asm}
\end_inset
\series default
- Shows the actual commands the compiler is executing.
+ Include i-codes in the asm file.
+ Sounds like noise but is most helpful for debugging the compiler itself.
\layout List
\labelwidthstring 00.00.0000
/
\end_inset
--no-c-code-in-asm
-\begin_inset LatexCommand \index{-\/-no-c-code-in-asm}
+-less-pedantic
+\begin_inset LatexCommand \index{-\/-less-pedantic}
\end_inset
\series default
- Hides your ugly and inefficient c-code from the asm file, so you can always
- blame the compiler :).
-\layout List
-\labelwidthstring 00.00.0000
-
-
-\series bold
--
-\begin_inset ERT
-status Collapsed
-
-\layout Standard
-
-\backslash
-/
-\end_inset
-
--i-code-in-asm
-\begin_inset LatexCommand \index{-\/-i-code-in-asm}
+ Disable some of the more pedantic warnings
+\begin_inset LatexCommand \index{Warnings}
\end_inset
-
-\series default
- Include i-codes in the asm file.
- Sounds like noise but is most helpful for debugging the compiler itself.
+ (jwk burps: please be more specific here, please!).
\layout List
\labelwidthstring 00.00.0000
/
\end_inset
--less-pedantic
-\begin_inset LatexCommand \index{-\/-less-pedantic}
+-disable-warning\SpecialChar ~
+<nnnn>
+\begin_inset LatexCommand \index{-\/-disable-warning}
\end_inset
\series default
- Disable some of the more pedantic warnings
-\begin_inset LatexCommand \index{Warnings}
-
-\end_inset
-
- (jwk burps: please be more specific here, please!).
- If you want rather more than less warnings you should consider using a
- separate tool dedicated to syntax checking like
-\begin_inset LatexCommand \url{www.splint.org}
-
-\end_inset
-
-.
+ Disable specific warning with number <nnnn>.
\layout List
\labelwidthstring 00.00.0000
\end_inset
...
- Pass the asmOption to the assembler.
-\layout Subsection
-
-Intermediate Dump Options
-\begin_inset LatexCommand \label{sub:Intermediate-Dump-Options}
-
-\end_inset
-
-
-\begin_inset LatexCommand \index{Options intermediate dump}
-
-\end_inset
-
-
-\begin_inset LatexCommand \index{Intermediate dump options}
+ Pass the asmOption to the assembler
+\begin_inset LatexCommand \index{Options assembler}
\end_inset
-\layout Standard
-
-The following options are provided for the purpose of retargetting and debugging
- the compiler.
- These provided a means to dump the intermediate code (iCode
-\begin_inset LatexCommand \index{iCode}
+\begin_inset LatexCommand \index{Assembler options}
\end_inset
-) generated by the compiler in human readable form at various stages of
- the compilation process.
-
+.
+ See file sdcc/as/doc/asxhtm.html for assembler options.cd
\layout List
\labelwidthstring 00.00.0000
/
\end_inset
--dumpraw
-\begin_inset LatexCommand \index{-\/-dumpraw}
+-std-sdcc89
+\begin_inset LatexCommand \index{-\/-std-sdcc89}
\end_inset
\series default
- This option will cause the compiler to dump the intermediate code into
- a file of named
-\emph on
-<source filename>.dumpraw
-\emph default
- just after the intermediate code has been generated for a function, i.e.
- before any optimizations are done.
- The basic blocks
-\begin_inset LatexCommand \index{Basic blocks}
-
-\end_inset
-
- at this stage ordered in the depth first number, so they may not be in
- sequence of execution.
+ Generally follow the C89 standard, but allow SDCC features that conflict
+ with the standard (default).
\layout List
\labelwidthstring 00.00.0000
/
\end_inset
--dumpgcse
-\begin_inset LatexCommand \index{-\/-dumpgcse}
+-std-c89
+\begin_inset LatexCommand \index{-\/-std-c89}
\end_inset
\series default
- Will create a dump of iCode's, after global subexpression elimination
-\begin_inset LatexCommand \index{Global subexpression elimination}
-
-\end_inset
-
-, into a file named
-\emph on
-<source filename>.dumpgcse.
+ Follow the C89 standard and disable SDCC features that conflict with the
+ standard.
\layout List
\labelwidthstring 00.00.0000
/
\end_inset
--dumpdeadcode
-\begin_inset LatexCommand \index{-\/-dumpdeadcode}
+-std-sdcc99
+\begin_inset LatexCommand \index{-\/-std-sdcc99}
\end_inset
\series default
- Will create a dump of iCode's, after deadcode elimination
-\begin_inset LatexCommand \index{Dead-code elimination}
-
-\end_inset
-
-, into a file named
-\emph on
-<source filename>.dumpdeadcode.
+ Generally follow the C99 standard, but allow SDCC features that conflict
+ with the standard (incomplete support).
\layout List
\labelwidthstring 00.00.0000
/
\end_inset
--dumploop
-\begin_inset LatexCommand \index{-\/-dumploop}
+-std-c99
+\begin_inset LatexCommand \index{-\/-std-sdcc99}
\end_inset
\series default
-\size large
-
-\size default
-Will create a dump of iCode's, after loop optimizations
-\begin_inset LatexCommand \index{Loop optimization}
-
-\end_inset
-
-, into a file named
-\emph on
-<source filename>.dumploop.
+ Follow the C99 standard and disable SDCC features that conflict with the
+ standard (incomplete support).
\layout List
\labelwidthstring 00.00.0000
/
\end_inset
--dumprange
-\begin_inset LatexCommand \index{-\/-dumprange}
+-codeseg
+\series default
-\end_inset
+\begin_inset LatexCommand \index{-\/-codeseg <Value>}
+\end_inset
-\series default
-\size large
-
-\size default
-Will create a dump of iCode's, after live range analysis
-\begin_inset LatexCommand \index{Live range analysis}
+\SpecialChar ~
+<Name> The name to be used for the code
+\begin_inset LatexCommand \index{code}
\end_inset
-, into a file named
-\emph on
-<source filename>.dumprange.
+ segment, default CSEG.
+ This is useful if you need to tell the compiler to put the code in a special
+ segment so you can later on tell the linker to put this segment in a special
+ place in memory.
+ Can be used for instance when using bank switching to put the code in a
+ bank.
\layout List
\labelwidthstring 00.00.0000
/
\end_inset
--dumlrange
-\begin_inset LatexCommand \index{-\/-dumlrange}
+-constseg
+\series default
-\end_inset
+\begin_inset LatexCommand \index{-\/-constseg <Value>}
+\end_inset
-\series default
- Will dump the life ranges
-\begin_inset LatexCommand \index{Live range analysis}
+\SpecialChar ~
+<Name> The name to be used for the const
+\begin_inset LatexCommand \index{code}
\end_inset
- for all symbols.
+ segment, default CONST.
+ This is useful if you need to tell the compiler to put the const data in
+ a special segment so you can later on tell the linker to put this segment
+ in a special place in memory.
+ Can be used for instance when using bank switching to put the const data
+ in a bank.
\layout List
\labelwidthstring 00.00.0000
\series bold
--
-\begin_inset ERT
-status Collapsed
-
-\layout Standard
+more-pedantic
+\series default
+ Actually this is
+\series bold
+\emph on
+not
+\series default
+\emph default
+ a SDCC compiler option but if you want
+\emph on
+more
+\emph default
+ warnings you can use a separate tool dedicated to syntax checking like
+ splint
+\begin_inset LatexCommand \label{lyx:more-pedantic-SPLINT}
-\backslash
-/
\end_inset
--dumpregassign
-\begin_inset LatexCommand \index{-\/-dumpregassign}
-\end_inset
+\begin_inset LatexCommand \index{lint (syntax checking tool)}
+\end_inset
-\bar under
-\series default
-\bar default
-Will create a dump of iCode's, after register assignment
-\begin_inset LatexCommand \index{Register assignment}
+\begin_inset LatexCommand \url{http://www.splint.org}
\end_inset
-, into a file named
-\emph on
-<source filename>.dumprassgn.
-\layout List
-\labelwidthstring 00.00.0000
+.
+ To make your source files parseable by splint you will have to include
+
+\family sans
+lint.h
+\family default
+
+\begin_inset LatexCommand \index{splint (syntax checking tool)}
+
+\end_inset
+
+ in your source file and add brackets around extended keywords (like
+\family sans
+
+\begin_inset Quotes sld
+\end_inset
+__at\SpecialChar ~
\series bold
--
-\begin_inset ERT
-status Collapsed
+(
+\series default
+0xab
+\series bold
+)
+\series default
+
+\begin_inset Quotes srd
+\end_inset
+
+
+\family default
+ and
+\family sans
+
+\begin_inset Quotes sld
+\end_inset
+
+__interrupt\SpecialChar ~
+(2)
+\begin_inset Quotes srd
+\end_inset
+
+
+\family default
+).
+
+\newline
+Splint has an excellent on line manual at
+\begin_inset LatexCommand \url{http://www.splint.org/manual/}
+
+\end_inset
+
+ and it's capabilities go beyond pure syntax checking.
+ You'll need to tell splint the location of SDCC's include files so a typical
+ command line could look like this:
+\newline
+
+\family sans
+splint\SpecialChar ~
+-I\SpecialChar ~
+/usr/local/share/sdcc/include/mcs51/\SpecialChar ~
+\SpecialChar ~
+myprogram.c
+\layout Subsection
+
+Intermediate Dump Options
+\begin_inset LatexCommand \label{sub:Intermediate-Dump-Options}
+
+\end_inset
+
+
+\begin_inset LatexCommand \index{Options intermediate dump}
+
+\end_inset
+
+
+\begin_inset LatexCommand \index{Intermediate dump options}
+
+\end_inset
+
\layout Standard
-\backslash
-/
+The following options are provided for the purpose of retargetting and debugging
+ the compiler.
+ They provide a means to dump the intermediate code (iCode
+\begin_inset LatexCommand \index{iCode}
+
\end_inset
--dumplrange
-\begin_inset LatexCommand \index{-\/-dumplrange}
+) generated by the compiler in human readable form at various stages of
+ the compilation process.
+ More on iCodes see chapter
+\begin_inset LatexCommand \ref{sub:The-anatomy-of}
+
+\end_inset
+
+\begin_inset Quotes srd
\end_inset
+The anatomy of the compiler
+\begin_inset Quotes srd
+\end_inset
-\series default
- Will create a dump of the live ranges of iTemp's
+.
\layout List
\labelwidthstring 00.00.0000
/
\end_inset
--dumpall
-\begin_inset LatexCommand \index{-\/-dumpall}
+-dumpraw
+\begin_inset LatexCommand \index{-\/-dumpraw}
\end_inset
-\size large
-\bar under
-
\series default
-\size default
-\bar default
-Will cause all the above mentioned dumps to be created.
-\layout Subsection
-
-Redirecting output on Windows Shells
-\layout Standard
-
-By default SDCC writes it's error messages to
-\begin_inset Quotes sld
-\end_inset
+ This option will cause the compiler to dump the intermediate code into
+ a file of named
+\emph on
+<source filename>.dumpraw
+\emph default
+ just after the intermediate code has been generated for a function, i.e.
+ before any optimizations are done.
+ The basic blocks
+\begin_inset LatexCommand \index{Basic blocks}
-standard error
-\begin_inset Quotes srd
\end_inset
-.
- To force all messages to
-\begin_inset Quotes sld
-\end_inset
+ at this stage ordered in the depth first number, so they may not be in
+ sequence of execution.
+\layout List
+\labelwidthstring 00.00.0000
-standard output
-\begin_inset Quotes srd
-\end_inset
- use
\series bold
-
-\series default
-\emph on
-
\begin_inset ERT
status Collapsed
/
\end_inset
+-dumpgcse
+\begin_inset LatexCommand \index{-\/-dumpgcse}
+
+\end_inset
+
-\series bold
-\emph default
--
\series default
-use-stdout
-\begin_inset LatexCommand \index{-\/-use-stdout}
+ Will create a dump of iCode's, after global subexpression elimination
+\begin_inset LatexCommand \index{Global subexpression elimination}
\end_inset
-.
- Aditionaly, if you happen to have visual studio installed in your windows
- machine, you can use it to compile your sources using a custom build and
- the SDCC -
+, into a file named
\emph on
+<source filename>.dumpgcse.
+\layout List
+\labelwidthstring 00.00.0000
+
+\series bold
+-
\begin_inset ERT
status Collapsed
/
\end_inset
-
-\emph default
--vc
-\begin_inset LatexCommand \index{-\/-vc}
+-dumpdeadcode
+\begin_inset LatexCommand \index{-\/-dumpdeadcode}
\end_inset
- option.
- Something like this should work:
-\newline
-
-\newline
-\series bold
-c:
-\backslash
-sdcc
-\backslash
-bin
-\backslash
-sdcc.exe -
\series default
+ Will create a dump of iCode's, after deadcode elimination
+\begin_inset LatexCommand \index{Dead-code elimination}
+
+\end_inset
+
+, into a file named
\emph on
+<source filename>.dumpdeadcode.
+\layout List
+\labelwidthstring 00.00.0000
+
+\series bold
+-
\begin_inset ERT
status Collapsed
/
\end_inset
+-dumploop
+\begin_inset LatexCommand \index{-\/-dumploop}
+
+\end_inset
+
-\series bold
-\emph default
--vc -
\series default
+\size large
+
+\size default
+Will create a dump of iCode's, after loop optimizations
+\begin_inset LatexCommand \index{Loop optimization}
+
+\end_inset
+
+, into a file named
\emph on
+<source filename>.dumploop.
+\layout List
+\labelwidthstring 00.00.0000
+
+\series bold
+-
\begin_inset ERT
status Collapsed
/
\end_inset
-
-\series bold
-\emph default
--model-large -c $(InputPath)
-\layout Section
-
-Environment variables
-\begin_inset LatexCommand \index{Environment variables}
+-dumprange
+\begin_inset LatexCommand \index{-\/-dumprange}
\end_inset
-\layout Standard
+\series default
+\size large
+
+\size default
+Will create a dump of iCode's, after live range analysis
+\begin_inset LatexCommand \index{Live range analysis}
-SDCC recognizes the following environment variables:
+\end_inset
+
+, into a file named
+\emph on
+<source filename>.dumprange.
\layout List
\labelwidthstring 00.00.0000
\series bold
-SDCC_LEAVE_SIGNALS
-\begin_inset LatexCommand \index{SDCC\_LEAVE\_SIGNALS}
+-
+\begin_inset ERT
+status Collapsed
+
+\layout Standard
+
+\backslash
+/
+\end_inset
+
+-dumlrange
+\begin_inset LatexCommand \index{-\/-dumlrange}
\end_inset
\series default
- SDCC installs a signal handler
-\begin_inset LatexCommand \index{signal handler}
+ Will dump the life ranges
+\begin_inset LatexCommand \index{Live range analysis}
\end_inset
- to be able to delete temporary files after an user break (^C) or an exception.
- If this environment variable is set, SDCC won't install the signal handler
- in order to be able to debug SDCC.
+ for all symbols.
\layout List
\labelwidthstring 00.00.0000
\series bold
-TMP,\SpecialChar ~
-TEMP,\SpecialChar ~
+-
+\begin_inset ERT
+status Collapsed
+
+\layout Standard
+
+\backslash
+/
+\end_inset
+
+-dumpregassign
+\begin_inset LatexCommand \index{-\/-dumpregassign}
+
+\end_inset
+
+
+\bar under
+
+\series default
+\bar default
+Will create a dump of iCode's, after register assignment
+\begin_inset LatexCommand \index{Register assignment}
+
+\end_inset
+
+, into a file named
+\emph on
+<source filename>.dumprassgn.
+\layout List
+\labelwidthstring 00.00.0000
+
+
+\series bold
+-
+\begin_inset ERT
+status Collapsed
+
+\layout Standard
+
+\backslash
+/
+\end_inset
+
+-dumplrange
+\begin_inset LatexCommand \index{-\/-dumplrange}
+
+\end_inset
+
+
+\series default
+ Will create a dump of the live ranges of iTemp's
+\layout List
+\labelwidthstring 00.00.0000
+
+
+\series bold
+-
+\begin_inset ERT
+status Collapsed
+
+\layout Standard
+
+\backslash
+/
+\end_inset
+
+-dumpall
+\begin_inset LatexCommand \index{-\/-dumpall}
+
+\end_inset
+
+
+\size large
+\bar under
+
+\series default
+\size default
+\bar default
+Will cause all the above mentioned dumps to be created.
+\layout Subsection
+
+Redirecting output on Windows Shells
+\layout Standard
+
+By default SDCC writes it's error messages to
+\begin_inset Quotes sld
+\end_inset
+
+standard error
+\begin_inset Quotes srd
+\end_inset
+
+.
+ To force all messages to
+\begin_inset Quotes sld
+\end_inset
+
+standard output
+\begin_inset Quotes srd
+\end_inset
+
+ use
+\series bold
+-
+\series default
+\emph on
+
+\begin_inset ERT
+status Collapsed
+
+\layout Standard
+
+\backslash
+/
+\end_inset
+
+
+\series bold
+\emph default
+-
+\series default
+use-stdout
+\begin_inset LatexCommand \index{-\/-use-stdout}
+
+\end_inset
+
+.
+ Additionally, if you happen to have visual studio installed in your windows
+ machine, you can use it to compile your sources using a custom build and
+ the SDCC -
+\emph on
+
+\begin_inset ERT
+status Collapsed
+
+\layout Standard
+
+\backslash
+/
+\end_inset
+
+
+\emph default
+-vc
+\begin_inset LatexCommand \index{-\/-vc}
+
+\end_inset
+
+ option.
+ Something like this should work:
+\newline
+
+\newline
+
+\series bold
+c:
+\backslash
+sdcc
+\backslash
+bin
+\backslash
+sdcc.exe -
+\series default
+\emph on
+
+\begin_inset ERT
+status Collapsed
+
+\layout Standard
+
+\backslash
+/
+\end_inset
+
+
+\series bold
+\emph default
+-vc -
+\series default
+\emph on
+
+\begin_inset ERT
+status Collapsed
+
+\layout Standard
+
+\backslash
+/
+\end_inset
+
+
+\series bold
+\emph default
+-model-large -c $(InputPath)
+\layout Section
+
+Environment variables
+\begin_inset LatexCommand \index{Environment variables}
+
+\end_inset
+
+
+\layout Standard
+
+SDCC recognizes the following environment variables:
+\layout List
+\labelwidthstring 00.00.0000
+
+
+\series bold
+SDCC_LEAVE_SIGNALS
+\begin_inset LatexCommand \index{SDCC\_LEAVE\_SIGNALS}
+
+\end_inset
+
+
+\series default
+ SDCC installs a signal handler
+\begin_inset LatexCommand \index{signal handler}
+
+\end_inset
+
+ to be able to delete temporary files after an user break (^C) or an exception.
+ If this environment variable is set, SDCC won't install the signal handler
+ in order to be able to debug SDCC.
+\layout List
+\labelwidthstring 00.00.0000
+
+
+\series bold
+TMP,\SpecialChar ~
+TEMP,\SpecialChar ~
TMPDIR
\begin_inset LatexCommand \index{TMP, TEMP, TMPDIR}
They can change or disappear very quickly, and will never be documented.
\layout Section
+Storage Class Language Extensions
+\layout Subsection
+
MCS51/DS390 Storage Class
\begin_inset LatexCommand \index{Storage class}
\layout Standard
In addition to the ANSI storage classes SDCC allows the following MCS51
- specific storage classes.
-\layout Subsection
+ specific storage classes:
+\layout Subsubsection
data
-\begin_inset LatexCommand \index{data}
+\begin_inset LatexCommand \index{data (mcs51, ds390 storage class)}
+
+\end_inset
+
+
+\begin_inset LatexCommand \index{\_\_data (mcs51, ds390 storage class)}
+
+\end_inset
+
+ / near
+\begin_inset LatexCommand \index{near (storage class)}
+
+\end_inset
+
+
+\begin_inset LatexCommand \index{\_\_near (storage class)}
\end_inset
\series bold
default
\series default
- storage class for the Small Memory model.
+ storage class for the Small Memory model (
+\emph on
+data
+\emph default
+ and
+\emph on
+near
+\emph default
+ can be used synonymously).
Variables declared with this storage class will be allocated in the directly
addressable portion of the internal RAM of a 8051, e.g.:
\layout Verse
mov\SpecialChar ~
\SpecialChar ~
_test_data,#0x01
-\layout Subsection
+\layout Subsubsection
xdata
-\begin_inset LatexCommand \index{xdata}
+\begin_inset LatexCommand \index{xdata (mcs51, ds390 storage class)}
\end_inset
-\layout Standard
+\begin_inset LatexCommand \index{\_\_xdata (mcs51, ds390 storage class)}
-Variables declared with this storage class will be placed in the external
- RAM.
- This is the
+\end_inset
+
+ / far
+\begin_inset LatexCommand \index{far (storage class)}
+
+\end_inset
+
+
+\begin_inset LatexCommand \index{\_\_far (storage class)}
+
+\end_inset
+
+
+\layout Standard
+
+Variables declared with this storage class will be placed in the external
+ RAM.
+ This is the
\series bold
default
\series default
\SpecialChar ~
movx\SpecialChar ~
@dptr,a
-\layout Subsection
+\layout Subsubsection
idata
-\begin_inset LatexCommand \index{idata}
+\begin_inset LatexCommand \index{idata (mcs51, ds390 storage class)}
+
+\end_inset
+
+
+\begin_inset LatexCommand \index{\_\_idata (mcs51, ds390 storage class)}
\end_inset
\SpecialChar ~
mov\SpecialChar ~
\SpecialChar ~
-@r0,#0x01
-\layout Subsection
+@r0,#0x01
+\layout Standard
+
+Please note, the first 128 byte of idata physically access the same RAM
+ as the data memory.
+ The original 8051 had 128 byte idata memory, nowadays most devices have
+ 256 byte idata memory.
+ The stack
+\begin_inset LatexCommand \index{stack}
+
+\end_inset
+
+ is located in idata memory.
+\layout Subsubsection
pdata
-\begin_inset LatexCommand \index{pdata}
+\begin_inset LatexCommand \index{pdata (mcs51, ds390 storage class)}
+
+\end_inset
+
+
+\begin_inset LatexCommand \index{\_\_pdata (mcs51, ds390 storage class)}
\end_inset
\layout Standard
-Paged xdata access is currently not as straightforward as using the other
- addressing modes of a 8051.
- The following example writes 0x01 to the address pointed to.
+Paged xdata access is just as straightforward as using the other addressing
+ modes of a 8051.
+ It is typically located at the start of xdata and has a maximum size of
+ 256 bytes.
+ The following example writes 0x01 to the pdata variable.
Please note, pdata access physically accesses xdata memory.
- The high byte of the address is determined by port P2 (or in case of some
- 8051 variants by a separate Special Function Register, see section
+ The high byte of the address is determined by port P2
+\begin_inset LatexCommand \index{P2 (mcs51 sfr)}
+
+\end_inset
+
+(or in case of some 8051 variants by a separate Special Function Register,
+ see section
\begin_inset LatexCommand \ref{sub:MCS51-variants}
\end_inset
).
+ This is the
+\series bold
+default
+\series default
+ storage class for the Medium Memory model, e.g.:
\layout Verse
\family typewriter
-pdata unsigned char *test_pdata_ptr;
-\newline
-
-\newline
-void main()
-\newline
-{
-\newline
-\SpecialChar ~
-\SpecialChar ~
-\SpecialChar ~
-\SpecialChar ~
-test_pdata_ptr = (pdata *)0xfe;
-\newline
-\SpecialChar ~
-\SpecialChar ~
-\SpecialChar ~
-\SpecialChar ~
-*test_pdata_ptr = 1;
-\newline
-}
+pdata unsigned char test_pdata;
\layout Standard
-Generates the assembly code:
+Writing 0x01 to this variable generates the assembly code:
\layout Verse
\family typewriter
-75*01 FE\SpecialChar ~
-\SpecialChar ~
-\SpecialChar ~
-mov\SpecialChar ~
- _test_pdata_ptr,#0xFE
-\newline
-78 FE\SpecialChar ~
+78r00\SpecialChar ~
\SpecialChar ~
\SpecialChar ~
\SpecialChar ~
\SpecialChar ~
\SpecialChar ~
-mov\SpecialChar ~
- r0,#0xFE
+mov r0,#_test_pdata
\newline
74 01\SpecialChar ~
\SpecialChar ~
\SpecialChar ~
\SpecialChar ~
\SpecialChar ~
-mov\SpecialChar ~
- a,#0x01
+mov a,#0x01
\newline
F2\SpecialChar ~
\SpecialChar ~
\SpecialChar ~
\SpecialChar ~
\SpecialChar ~
-movx @r0,a
+movx @r0,a
\layout Standard
-Be extremely carefull if you use pdata together with the -
+If the -
\begin_inset ERT
status Collapsed
\end_inset
- option.
-\layout Subsection
+ option is used the pdata memory area is followed by the xstack memory area
+ and the sum of their sizes is limited to 256 bytes.
+\layout Subsubsection
code
\begin_inset LatexCommand \index{code}
\end_inset
+\begin_inset LatexCommand \index{\_\_code}
+
+\end_inset
+
+
\layout Standard
'Variables' declared with this storage class will be placed in the code
\SpecialChar ~
\SpecialChar ~
movc a,@a+dptr
-\layout Subsection
+\layout Standard
+
+
+\family typewriter
+char
+\family default
+ indexed arrays of characters in code memory can be accessed efficiently:
+\layout Verse
+
+
+\family typewriter
+code char test_array[] = {'c','h','e','a','p'};
+\layout Standard
+
+Read access to this array using an 8-bit unsigned index generates the assembly
+ code:
+\layout Verse
+
+
+\family typewriter
+E5*00\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+mov a,_index
+\layout Verse
+
+
+\family typewriter
+90s00r41\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+mov dptr,#_test_array
+\layout Verse
+
+
+\family typewriter
+93\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+movc a,@a+dptr
+\layout Subsubsection
bit
\begin_inset LatexCommand \index{bit}
\end_inset
+\begin_inset LatexCommand \index{\_\_bit}
+
+\end_inset
+
+
\layout Standard
This is a data-type and a storage class specifier.
_test_bit
\layout Standard
+The bit addressable memory consists of 128 bits which are located from 0x20
+ to 0x2f in data memory.
+
+\newline
Apart from this 8051 specific storage class most architectures support ANSI-C
bitfields
\begin_inset LatexCommand \index{bitfields}
\end_inset
-
+
\begin_inset Foot
collapsed false
\end_inset
.
-\layout Subsection
+ In accordance with ISO/IEC 9899 bits and bitfields without an explicit
+ signed modifier are implemented as unsigned.
+\layout Subsubsection
sfr
\begin_inset LatexCommand \index{sfr}
+\end_inset
+
+
+\begin_inset LatexCommand \index{\_\_sfr}
+
+\end_inset
+
+ / sfr16
+\begin_inset LatexCommand \index{sfr16}
+
+\end_inset
+
+
+\begin_inset LatexCommand \index{\_\_sfr16}
+
+\end_inset
+
+ / sfr32
+\begin_inset LatexCommand \index{sfr32}
+
+\end_inset
+
+
+\begin_inset LatexCommand \index{\_\_sfr32}
+
\end_inset
/ sbit
-\begin_inset LatexCommand \index{sbit}
+\begin_inset LatexCommand \index{\_\_sbit}
\end_inset
Like the bit keyword,
\emph on
-sfr / sbit
+sfr / sfr16 / sfr32 / sbit
+\emph default
+signify both a data-type and storage class, they are used to describe the
+
+\emph on
+s
+\emph default
+pecial
+\emph on
+f
+\emph default
+unction
+\emph on
+r
+\emph default
+egisters and
+\emph on
+s
+\emph default
+pecial
+\emph on
+bit
\emph default
-signifies both a data-type and storage class, they are used to describe
- the special function registers and special bit variables of a 8051, eg:
+ variables of a 8051, eg:
\layout Verse
sfr at
\begin_inset LatexCommand \index{at}
+\end_inset
+
+
+\begin_inset LatexCommand \index{\_\_at}
+
\end_inset
0x80 P0;\SpecialChar ~
/* special function register P0 at location 0x80 */
\newline
+/* 16 bit special function register combination for timer 0 */
+\newline
+/* with the high byte at location 0x8C and the low byte at location 0x8A
+ */
+\newline
+sfr16 at
+\begin_inset LatexCommand \index{at}
+
+\end_inset
+
+
+\begin_inset LatexCommand \index{\_\_at}
+
+\end_inset
+
+ 0x8C8A TMR0;
+\newline
sbit at 0xd7 CY; /* CY (Carry Flag
\begin_inset LatexCommand \index{Flags}
\end_inset
) */
-\layout Subsection
+\layout Standard
+
+Special function registers which are located on an address dividable by
+ 8 are bit-addressable, an
+\emph on
+ sbit
+\emph default
+ addresses a specific bit within these sfr.
+\newline
+16 Bit and 32 bit special function register combinations which require a
+ certain access order are better not declared using
+\emph on
+sfr16
+\emph default
+ or
+\emph on
+sfr32.
+
+\emph default
+ Allthough SDCC usually accesses them Least Significant Byte (LSB) first,
+ this is not guaranteed.
+\layout Subsubsection
Pointers
-\begin_inset LatexCommand \index{Pointers}
+\begin_inset LatexCommand \index{Pointer}
\end_inset
*/
\newline
char * xdata p;
+\newline
+
+\newline
+/* the following is a function pointer physically located in data space
+ */
+\newline
+char (* data fp)(void);
\layout Standard
Well you get the idea.
routines.
Explicitly specifying the pointer type will generate the most efficient
code.
-\layout Section
+\layout Subsubsection
-Absolute Addressing
-\begin_inset LatexCommand \index{Absolute addressing}
+Notes on MCS51 memory
+\begin_inset LatexCommand \index{MCS51 memory}
\end_inset
-
+ layout
\layout Standard
-Data items can be assigned an absolute address with the
-\emph on
-at
-\begin_inset LatexCommand \index{at}
+The 8051 family of microcontrollers have a minimum of 128 bytes of internal
+ RAM memory which is structured as follows:
+\newline
-\end_inset
+\newline
+- Bytes 00-1F - 32 bytes to hold up to 4 banks of the registers R0 to R7,
+
+\newline
+- Bytes 20-2F - 16 bytes to hold 128 bit
+\begin_inset LatexCommand \index{bit}
- <address>
-\emph default
- keyword, in addition to a storage class, e.g.:
-\layout Verse
+\end_inset
+ variables and,
+\newline
+- Bytes 30-7F - 80 bytes for general purpose use.
+\newline
-\family typewriter
-xdata
-\begin_inset LatexCommand \index{xdata}
+\layout Standard
-\end_inset
+Additionally some members of the MCS51 family may have up to 128 bytes of
+ additional, indirectly addressable, internal RAM memory (
+\emph on
+idata
+\emph default
- at
-\begin_inset LatexCommand \index{at}
+\begin_inset LatexCommand \index{idata (mcs51, ds390 storage class)}
\end_inset
- 0x7ffe unsigned int chksum;
-\layout Standard
-In the above example the variable chksum will located at 0x7ffe and 0x7fff
- of the external ram.
- The compiler does not actually reserve any space for variables declared
- in this way (they are implemented with an equate in the assembler).
- Thus it is left to the programmer to make sure there are no overlaps with
- other variables that are declared without the absolute address.
- The assembler listing file (.lst
-\begin_inset LatexCommand \index{<file>.lst}
+\begin_inset LatexCommand \index{\_\_idata (mcs51, ds390 storage class)}
\end_inset
-) and the linker output files (.rst
-\begin_inset LatexCommand \index{<file>.rst}
+).
+ Furthermore, some chips may have some built in external memory (
+\emph on
+xdata
+\emph default
+
+\begin_inset LatexCommand \index{xdata (mcs51, ds390 storage class)}
\end_inset
-) and (.map
-\begin_inset LatexCommand \index{<file>.map}
-\end_inset
+\begin_inset LatexCommand \index{\_\_xdata (mcs51, ds390 storage class)}
-) are good places to look for such overlaps.
-\layout Standard
+\end_inset
-In case of memory mapped I/O devices the keyword
+) which should not be confused with the internal, directly addressable RAM
+ memory (
\emph on
-volatile
+data
\emph default
- should be used to tell the compiler that accesses might not be optimized
- away:
-\layout Verse
-
-\family typewriter
-volatile
-\begin_inset LatexCommand \index{volatile}
+\begin_inset LatexCommand \index{data (mcs51, ds390 storage class)}
\end_inset
- xdata
-\begin_inset LatexCommand \index{xdata}
-\end_inset
-
- at
-\begin_inset LatexCommand \index{at}
-
-\end_inset
-
- 0x8000 unsigned char PORTA_8255;
-\layout Standard
-
-Absolute address can be specified for variables in all storage classes,
- e.g.:
-\layout Verse
-
-
-\family typewriter
-bit
-\begin_inset LatexCommand \index{bit}
+\begin_inset LatexCommand \index{\_\_data (mcs51, ds390 storage class)}
\end_inset
- at
-\begin_inset LatexCommand \index{at}
+).
+ Sometimes this built in
+\emph on
+xdata
+\emph default
+ memory has to be activated before using it (you can probably find this
+ information on the datasheet of the microcontroller your are using, see
+ also section
+\begin_inset LatexCommand \ref{sub:Startup-Code}
\end_inset
- 0x02 bvar;
-\layout Standard
-
-The above example will allocate the variable at offset 0x02 in the bit-addressab
-le space.
- There is no real advantage to assigning absolute addresses to variables
- in this manner, unless you want strict control over all the variables allocated.
- One possible use would be to write hardware portable code.
- For example, if you have a routine that uses one or more of the microcontroller
- I/O pins, and such pins are different for two different hardwares, you
- can declare the I/O pins in your routine using:
-\layout Verse
-
-
-\family typewriter
-extern volatile bit SDI;
-\newline
-extern volatile bit SCLK;
-\newline
-extern volatile bit CPOL;
-\newline
-
-\newline
-void DS1306_put(unsigned char value)
-\newline
-{
-\newline
-\SpecialChar ~
-\SpecialChar ~
-\SpecialChar ~
-\SpecialChar ~
-unsigned char mask=0x80;
-\newline
-
-\newline
-\SpecialChar ~
-\SpecialChar ~
-\SpecialChar ~
-\SpecialChar ~
-while(mask)
-\newline
-\SpecialChar ~
\SpecialChar ~
-\SpecialChar ~
-\SpecialChar ~
-{
-\newline
-\SpecialChar ~
-\SpecialChar ~
-\SpecialChar ~
-\SpecialChar ~
-\SpecialChar ~
-\SpecialChar ~
-\SpecialChar ~
-\SpecialChar ~
-SDI=(value & mask)?1:0;
-\newline
-\SpecialChar ~
-\SpecialChar ~
-\SpecialChar ~
-\SpecialChar ~
-\SpecialChar ~
-\SpecialChar ~
-\SpecialChar ~
-\SpecialChar ~
-SCLK=!CPOL;
-\newline
-\SpecialChar ~
-\SpecialChar ~
-\SpecialChar ~
-\SpecialChar ~
-\SpecialChar ~
-\SpecialChar ~
-\SpecialChar ~
-\SpecialChar ~
-SCLK=CPOL;
-\newline
-\SpecialChar ~
-\SpecialChar ~
-\SpecialChar ~
-\SpecialChar ~
-\SpecialChar ~
-\SpecialChar ~
-\SpecialChar ~
-\SpecialChar ~
-mask/=2;
-\newline
-\SpecialChar ~
-\SpecialChar ~
-\SpecialChar ~
-\SpecialChar ~
-}
-\newline
-}
+Startup-Code).
\layout Standard
-Then, someplace in the code for the first hardware you would use
-\layout Verse
-
-
-\family typewriter
-bit at 0x80 SDI;\SpecialChar ~
-\SpecialChar ~
-\SpecialChar ~
-\SpecialChar ~
-/* I/O port 0, bit 0 */
-\newline
-bit at 0x81 SCLK;\SpecialChar ~
-\SpecialChar ~
-\SpecialChar ~
-/* I/O port 0, bit 1 */
-\newline
-bit CPOL;\SpecialChar ~
-\SpecialChar ~
-\SpecialChar ~
-\SpecialChar ~
-\SpecialChar ~
-\SpecialChar ~
-\SpecialChar ~
-\SpecialChar ~
-\SpecialChar ~
-\SpecialChar ~
-\SpecialChar ~
-/* This is a variable, let the linker allocate this one */
-\layout Standard
+Normally SDCC will only use the first bank
+\begin_inset LatexCommand \index{register bank (mcs51, ds390)}
-Similarly, for the second hardware you would use
-\layout Verse
+\end_inset
+ of registers (register bank 0), but it is possible to specify that other
+ banks of registers (keyword
+\emph on
+using
+\emph default
+
+\emph on
-\family typewriter
-bit at 0x83 SDI;\SpecialChar ~
-\SpecialChar ~
-\SpecialChar ~
-\SpecialChar ~
-/* I/O port 0, bit 3 */
-\newline
-bit at 0x91 SCLK;\SpecialChar ~
-\SpecialChar ~
-\SpecialChar ~
-/* I/O port 1, bit 1 */
-\newline
-bit
-\begin_inset LatexCommand \index{bit}
+\begin_inset LatexCommand \index{using (mcs51, ds390 register bank)}
\end_inset
- CPOL;\SpecialChar ~
-\SpecialChar ~
-\SpecialChar ~
-\SpecialChar ~
-\SpecialChar ~
-\SpecialChar ~
-\SpecialChar ~
-\SpecialChar ~
-\SpecialChar ~
-\SpecialChar ~
-\SpecialChar ~
-/* This is a variable, let the linker allocate this one */
-\layout Standard
-
-and you can use the same hardware dependent routine without changes, as
- for example in a library.
- This is somehow similar to sbit, but only one absolute address has to be
- specified in the whole project.
-\layout Section
-Parameters
-\begin_inset LatexCommand \index{Parameters}
+\begin_inset LatexCommand \index{\_\_using (mcs51, ds390 register bank)}
\end_inset
-\begin_inset LatexCommand \index{function parameter}
+\emph default
+) should be used in interrupt
+\begin_inset LatexCommand \index{interrupt}
\end_inset
- & Local Variables
-\begin_inset LatexCommand \index{Local variable}
-
-\end_inset
+\begin_inset LatexCommand \index{\_\_interrupt}
-\layout Standard
+\end_inset
-Automatic (local) variables and parameters to functions can either be placed
- on the stack or in data-space.
- The default action of the compiler is to place these variables in the internal
- RAM (for small model) or external RAM (for large model).
- This in fact makes them similar to
+ routines.
+ By default, the compiler will place the stack after the last byte of allocated
+ memory for variables.
+ For example, if the first 2 banks of registers are used, and only four
+ bytes are used for
\emph on
-static
-\begin_inset LatexCommand \index{static}
+data
+\emph default
+ variables, it will position the base of the internal stack at address 20
+ (0x14).
+ This implies that as the stack
+\begin_inset LatexCommand \index{stack}
\end_inset
-
+ grows, it will use up the remaining register banks, and the 16 bytes used
+ by the 128 bit variables, and 80 bytes for general purpose use.
+ If any bit variables are used, the data variables will be placed in unused
+ register banks and after the byte holding the last bit variable.
+ For example, if register banks 0 and 1 are used, and there are 9 bit variables
+ (two bytes used),
+\emph on
+data
\emph default
- so by default functions are non-reentrant
-\begin_inset LatexCommand \index{reentrant}
+ variables will be placed starting from address 0x10 to 0x20 and continue
+ at address 0x22.
+ You can also use -
+\begin_inset ERT
+status Collapsed
-\end_inset
+\layout Standard
-.
-
-\newline
+\backslash
+/
+\end_inset
-\newline
-They can be placed on the stack
-\begin_inset LatexCommand \index{stack}
+-data-loc
+\begin_inset LatexCommand \index{-\/-data-loc <Value>}
\end_inset
- either by using the
+ to specify the start address of the
\emph on
- -
+data
+\emph default
+ and -
\begin_inset ERT
status Collapsed
/
\end_inset
--stack-auto
-\begin_inset LatexCommand \index{-\/-stack-auto}
+-iram-size
+\begin_inset LatexCommand \index{-\/-iram-size <Value>}
\end_inset
-
+ to specify the size of the total internal RAM (
+\emph on
+data
\emph default
- option or by using the
++
\emph on
-reentrant
-\begin_inset LatexCommand \index{reentrant}
+idata
+\emph default
+).
+
+\layout Standard
-\end_inset
+By default the 8051 linker will place the stack after the last byte of (i)data
+ variables.
+ Option -
+\begin_inset ERT
+status Collapsed
+\layout Standard
-\emph default
- keyword in the function declaration, e.g.:
-\layout Verse
+\backslash
+/
+\end_inset
+-stack-loc
+\begin_inset LatexCommand \index{-\/-stack-loc <Value>}
-\family typewriter
-unsigned char foo(char i) reentrant
-\newline
-{
-\newline
-\SpecialChar ~
-\SpecialChar ~
-\SpecialChar ~
-\SpecialChar ~
-...
-
-\newline
-}
-\layout Standard
+\end_inset
-Since stack space on 8051 is limited, the
+ allows you to specify the start of the stack, i.e.
+ you could start it after any data in the general purpose area.
+ If your microcontroller has additional indirectly addressable internal
+ RAM (
\emph on
-reentrant
+idata
\emph default
-keyword or the
-\emph on
- -
+) you can place the stack on it.
+ You may also need to use -
\begin_inset ERT
status Collapsed
/
\end_inset
--stack-auto
-\emph default
- option should be used sparingly.
- Note that the reentrant keyword just means that the parameters & local
- variables will be allocated to the stack, it
-\emph on
-does not
-\emph default
- mean that the function is register bank independent.
-\newline
-
-\newline
-Local variables can be assigned storage classes and absolute
-\begin_inset LatexCommand \index{Absolute addressing}
+-xdata-loc
+\begin_inset LatexCommand \index{-\/-xdata-loc<Value>}
\end_inset
- addresses, e.g.:
-\layout Verse
-
-
-\family typewriter
-unsigned char foo()
-\newline
-{
-\newline
-\SpecialChar ~
-\SpecialChar ~
-\SpecialChar ~
-\SpecialChar ~
-xdata unsigned char i;
-\newline
-\SpecialChar ~
-\SpecialChar ~
-\SpecialChar ~
-\SpecialChar ~
-bit bvar;
-\newline
-\SpecialChar ~
-\SpecialChar ~
-\SpecialChar ~
-\SpecialChar ~
-data at 0x31 unsigned char j;
-\newline
-\SpecialChar ~
-\SpecialChar ~
-\SpecialChar ~
-\SpecialChar ~
-...
-
-\newline
-}
-\layout Standard
-
-In the above example the variable
-\emph on
-i
-\emph default
- will be allocated in the external ram,
-\emph on
-bvar
-\emph default
- in bit addressable space and
+ to set the start address of the external RAM (
\emph on
- j
+xdata
\emph default
- in internal ram.
- When compiled with
-\emph on
--
+) and -
\begin_inset ERT
status Collapsed
/
\end_inset
--stack-auto
-\emph default
- or when a function is declared as
-\emph on
-reentrant
-\emph default
- this should only be done for static variables.
-\layout Standard
-
-Parameters
-\begin_inset LatexCommand \index{function parameter}
+-xram-size
+\begin_inset LatexCommand \index{-\/-xram-size <Value>}
\end_inset
- however are not allowed any storage class
-\begin_inset LatexCommand \index{storage class}
+ to specify its size.
+ Same goes for the code memory, using -
+\begin_inset ERT
+status Collapsed
-\end_inset
+\layout Standard
-, (storage classes for parameters will be ignored), their allocation is
- governed by the memory model in use, and the reentrancy options.
-\layout Section
+\backslash
+/
+\end_inset
-Overlaying
-\begin_inset LatexCommand \label{sub:Overlaying}
+-code-loc
+\begin_inset LatexCommand \index{-\/-code-loc <Value>}
\end_inset
+ and -
+\begin_inset ERT
+status Collapsed
-\begin_inset LatexCommand \index{Overlaying}
+\layout Standard
+\backslash
+/
\end_inset
+-code-size
+\begin_inset LatexCommand \index{-\/-code-size <Value>}
+
+\end_inset
+.
+ If in doubt, don't specify any options and see if the resulting memory
+ layout is appropriate, then you can adjust it.
\layout Standard
-For non-reentrant
-\begin_inset LatexCommand \index{reentrant}
+The linker generates two files with memory allocation information.
+ The first, with extension .map
+\begin_inset LatexCommand \index{<file>.map}
\end_inset
- functions SDCC will try to reduce internal ram space usage by overlaying
- parameters and local variables of a function (if possible).
- Parameters and local variables of a function will be allocated to an overlayabl
-e segment if the function has
-\emph on
-no other function calls and the function is non-reentrant and the memory
- model
-\begin_inset LatexCommand \index{Memory model}
+ shows all the variables and segments.
+ The second with extension .mem
+\begin_inset LatexCommand \index{<file>.mem}
\end_inset
- is small.
+ shows the final memory layout.
+ The linker will complain either if memory segments overlap, there is not
+ enough memory, or there is not enough space for stack.
+ If you get any linking warnings and/or errors related to stack or segments
+ allocation, take a look at either the .map or .mem files to find out what
+ the problem is.
+ The .mem file may even suggest a solution to the problem.
+\layout Subsection
-\emph default
- If an explicit storage class
+Z80/Z180 Storage Class
\begin_inset LatexCommand \index{Storage class}
\end_inset
- is specified for a local variable, it will NOT be overlayed.
-\layout Standard
+ Language Extensions
+\layout Subsubsection
-Note that the compiler (not the linkage editor) makes the decision for overlayin
-g the data items.
- Functions that are called from an interrupt service routine should be preceded
- by a #pragma\SpecialChar ~
-NOOVERLAY
-\begin_inset LatexCommand \index{\#pragma NOOVERLAY}
+sfr
+\begin_inset LatexCommand \index{sfr}
\end_inset
- if they are not reentrant.
-\layout Standard
-Also note that the compiler does not do any processing of inline assembler
- code, so the compiler might incorrectly assign local variables and parameters
- of a function into the overlay segment if the inline assembler code calls
- other c-functions that might use the overlay.
- In that case the #pragma\SpecialChar ~
-NOOVERLAY should be used.
+\begin_inset LatexCommand \index{\_\_sfr}
+
+\end_inset
+
+ (in/out to 8-bit addresses)
\layout Standard
-Parameters and local variables of functions that contain 16 or 32 bit multiplica
-tion
-\begin_inset LatexCommand \index{Multiplication}
+The Z80
+\begin_inset LatexCommand \index{Z80}
\end_inset
- or division
-\begin_inset LatexCommand \index{Division}
+ family has separate address spaces for memory and
+\emph on
+i
+\emph default
+nput/
+\emph on
+o
+\emph default
+utput memory.
+ I/O memory
+\begin_inset LatexCommand \index{I/O memory (Z80, Z180)}
\end_inset
- will NOT be overlayed since these are implemented using external functions,
- e.g.:
+ is accessed with special instructions, e.g.:
\layout Verse
\family typewriter
-#pragma SAVE
-\newline
-#pragma NOOVERLAY
-\begin_inset LatexCommand \index{\#pragma NOOVERLAY}
-
-\end_inset
-
-
-\newline
-void set_error(unsigned char errcd)
-\newline
-{
-\newline
-\SpecialChar ~
-\SpecialChar ~
-\SpecialChar ~
+sfr at 0x78 IoPort;\SpecialChar ~
\SpecialChar ~
-P3 = errcd;
-\newline
-}
-\newline
-#pragma RESTORE
-\newline
+/* define a var in I/O space at 78h called IoPort */
+
+\layout Standard
-\newline
-void some_isr () interrupt
-\begin_inset LatexCommand \index{interrupt}
+Writing 0x01 to this variable generates the assembly code:
+\layout Verse
-\end_inset
- 2
-\newline
-{
-\newline
-\SpecialChar ~
-\SpecialChar ~
-\SpecialChar ~
+\family typewriter
+3E 01\SpecialChar ~
\SpecialChar ~
-...
-\newline
\SpecialChar ~
\SpecialChar ~
\SpecialChar ~
\SpecialChar ~
-set_error(10);
+ld a,#0x01
\newline
+D3 78\SpecialChar ~
\SpecialChar ~
\SpecialChar ~
\SpecialChar ~
\SpecialChar ~
-...
-
-\newline
-}
-\layout Standard
-
-In the above example the parameter
-\emph on
-errcd
-\emph default
- for the function
-\emph on
-set_error
-\emph default
- would be assigned to the overlayable segment if the #pragma\SpecialChar ~
-NOOVERLAY was
- not present, this could cause unpredictable runtime behavior when called
- from an ISR.
- The #pragma\SpecialChar ~
-NOOVERLAY ensures that the parameters and local variables for
- the function are NOT overlayed.
-\layout Section
+\SpecialChar ~
+out (_IoPort),a
+\layout Subsubsection
-Interrupt Service Routines
-\begin_inset LatexCommand \label{sub:Interrupt-Service-Routines}
+banked sfr
+\begin_inset LatexCommand \index{sfr}
\end_inset
+\begin_inset LatexCommand \index{\_\_sfr}
+
+\end_inset
+
+ (in/out to 16-bit addresses)
\layout Standard
-SDCC allows interrupt service routines to be coded in C, with some extended
- keywords.
+The keyword
+\emph on
+banked
+\emph default
+ is used to support 16 bit addresses in I/O memory e.g.:
\layout Verse
\family typewriter
-void timer_isr (void) interrupt 1 using 1
-\newline
-{
-\newline
-\SpecialChar ~
-\SpecialChar ~
-\SpecialChar ~
-\SpecialChar ~
-...
-
-\newline
-}
-\layout Standard
-
-The optional number following the
-\emph on
-interrupt
-\begin_inset LatexCommand \index{interrupt}
+sfr banked at
+\begin_inset LatexCommand \index{at}
\end_inset
-\emph default
- keyword is the interrupt number this routine will service.
- When present, the compiler will insert a call to this routine in the interrupt
- vector table for the interrupt number specified.
- The
-\emph on
-using
-\emph default
- keyword can be used to tell the compiler to use the specified register
- bank (8051 specific) when generating code for this function.
-
-\newline
+\begin_inset LatexCommand \index{\_\_at}
-\layout Standard
+\end_inset
-If you have multiple source files in your project, interrupt service routines
- can be present in any of them, but a prototype of the isr MUST be present
- or included in the file that contains the function
-\emph on
-main
-\emph default
-.
+ 0x123 IoPort;
\layout Standard
-Interrupt numbers and the corresponding address & descriptions for the Standard
- 8051/8052 are listed below.
- SDCC will automatically adjust the interrupt vector table to the maximum
- interrupt number specified.
-\newline
+Writing 0x01 to this variable generates the assembly code:
+\layout Verse
-\layout Standard
-\align center
-\begin_inset Tabular
-<lyxtabular version="3" rows="7" columns="3">
-<features>
-<column alignment="center" valignment="top" leftline="true" width="0in">
-<column alignment="center" valignment="top" leftline="true" width="0in">
-<column alignment="center" valignment="top" leftline="true" rightline="true" width="0in">
-<row topline="true" bottomline="true">
-<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
-\begin_inset Text
+\family typewriter
+01 23 01\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+ld bc,#_IoPort
+\newline
+3E 01\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+ld a,#0x01
+\newline
+ED 79\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+out (c),a
+\layout Subsubsection
-\layout Standard
+sfr
+\begin_inset LatexCommand \index{sfr}
-Interrupt #
\end_inset
-</cell>
-<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
-\begin_inset Text
-\layout Standard
-Description
+\begin_inset LatexCommand \index{\_\_sfr}
+
\end_inset
-</cell>
-<cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
-\begin_inset Text
-\layout Standard
+ (in0/out0 to 8 bit addresses on Z180
+\begin_inset LatexCommand \index{Z180}
-Vector Address
\end_inset
-</cell>
-</row>
-<row topline="true">
-<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
-\begin_inset Text
-\layout Standard
+/HD64180
+\begin_inset LatexCommand \index{HD64180}
-0
\end_inset
-</cell>
-<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
-\begin_inset Text
+)
\layout Standard
-External 0
-\end_inset
-</cell>
-<cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
-\begin_inset Text
+The compiler option -
+\begin_inset ERT
+status Collapsed
\layout Standard
-0x0003
+\backslash
+/
\end_inset
-</cell>
-</row>
-<row topline="true">
-<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
-\begin_inset Text
-\layout Standard
+-portmode=180 (80) and a compiler #pragma\SpecialChar ~
+portmode
+\begin_inset LatexCommand \index{\#pragma portmode}
-1
\end_inset
-</cell>
-<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
-\begin_inset Text
-\layout Standard
+=z180 (z80) is used to turn on (off) the Z180/HD64180 port addressing instructio
+ns
+\family typewriter
+in0/out0
+\family default
+ instead of
+\family typewriter
+in/out
+\family default
+.
+ If you include the file z180.h this will be set automatically.
+\layout Subsection
+
+HC08 Storage Class
+\begin_inset LatexCommand \index{Storage class}
-Timer 0
\end_inset
-</cell>
-<cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
-\begin_inset Text
-\layout Standard
+ Language Extensions
+\layout Subsubsection
+
+data
+\begin_inset LatexCommand \index{data (hc08 storage class)}
-0x000B
\end_inset
-</cell>
-</row>
-<row topline="true">
-<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
-\begin_inset Text
-\layout Standard
-2
+\begin_inset LatexCommand \index{\_\_data (hc08 storage class)}
+
\end_inset
-</cell>
-<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
-\begin_inset Text
+
\layout Standard
-External 1
-\end_inset
-</cell>
-<cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
-\begin_inset Text
+The data storage class declares a variable that resides in the first 256
+ bytes of memory (the direct page).
+ The HC08 is most efficient at accessing variables (especially pointers)
+ stored here.
+\layout Subsubsection
-\layout Standard
+xdata
+\begin_inset LatexCommand \index{xdata (hc08 storage class)}
-0x0013
\end_inset
-</cell>
-</row>
-<row topline="true">
-<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
-\begin_inset Text
-\layout Standard
-3
+\begin_inset LatexCommand \index{\_\_xdata (hc08 storage class)}
+
\end_inset
-</cell>
-<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
-\begin_inset Text
+
\layout Standard
-Timer 1
-\end_inset
-</cell>
-<cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
-\begin_inset Text
+The xdata storage class declares a variable that can reside anywhere in
+ memory.
+ This is the default if no storage class is specified.
+
+\layout Section
-\layout Standard
+Absolute Addressing
+\begin_inset LatexCommand \index{Absolute addressing}
-0x001B
\end_inset
-</cell>
-</row>
-<row topline="true">
-<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
-\begin_inset Text
+
\layout Standard
-4
+Data items can be assigned an absolute address with the
+\emph on
+at
+\begin_inset LatexCommand \index{at}
+
\end_inset
-</cell>
-<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
-\begin_inset Text
-\layout Standard
-Serial
+\begin_inset LatexCommand \index{\_\_at}
+
\end_inset
-</cell>
-<cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
-\begin_inset Text
-\layout Standard
+ <address>
+\emph default
+ keyword, in addition to a storage class, e.g.:
+\layout Verse
-0x0023
-\end_inset
-</cell>
-</row>
-<row topline="true" bottomline="true">
-<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
-\begin_inset Text
-\layout Standard
+\family typewriter
+xdata
+\begin_inset LatexCommand \index{xdata (mcs51, ds390 storage class)}
-5
\end_inset
-</cell>
-<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
-\begin_inset Text
-\layout Standard
-Timer 2 (8052)
+\begin_inset LatexCommand \index{\_\_xdata (mcs51, ds390 storage class)}
+
\end_inset
-</cell>
-<cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
-\begin_inset Text
-\layout Standard
+ at
+\begin_inset LatexCommand \index{at}
-0x002B
\end_inset
-</cell>
-</row>
-</lyxtabular>
-\end_inset
+\begin_inset LatexCommand \index{\_\_at}
-\newline
+\end_inset
+ 0x7ffe unsigned int chksum;
\layout Standard
-If the interrupt service routine is defined without
+In the above example the variable chksum will be located at 0x7ffe and 0x7fff
+ of the external ram.
+ The compiler does
\emph on
-using
-\begin_inset LatexCommand \index{using}
+not
+\emph default
+ reserve any space for variables declared in this way (they are implemented
+ with an equate in the assembler).
+ Thus it is left to the programmer to make sure there are no overlaps with
+ other variables that are declared without the absolute address.
+ The assembler listing file (.lst
+\begin_inset LatexCommand \index{<file>.lst}
\end_inset
+) and the linker output files (.rst
+\begin_inset LatexCommand \index{<file>.rst}
-\emph default
- a register bank or with register bank 0 (using 0), the compiler will save
- the registers used by itself on the stack upon entry and restore them at
- exit, however if such an interrupt service routine calls another function
- then the entire register bank will be saved on the stack.
- This scheme may be advantageous for small interrupt service routines which
- have low register usage.
-\layout Standard
+\end_inset
-If the interrupt service routine is defined to be using a specific register
- bank then only
-\emph on
-a, b & dptr
-\emph default
- are save and restored, if such an interrupt service routine calls another
- function (using another register bank) then the entire register bank of
- the called function will be saved on the stack.
- This scheme is recommended for larger interrupt service routines.
-\layout Standard
+) and (.map
+\begin_inset LatexCommand \index{<file>.map}
-Using interrupts opens the door for some very interesting bugs:
-\layout Standard
+\end_inset
-If the interrupt service routines changes variables which are accessed by
- other functions these variables should be declared
+) are good places to look for such overlaps.
+ Variables with an absolute address are
\emph on
-volatile
+not
\emph default
-
-\begin_inset LatexCommand \index{volatile}
+ initialized
+\begin_inset LatexCommand \index{Variable initialization}
\end_inset
.
- If the access to these variables is not
-\emph on
-atomic
-\begin_inset LatexCommand \index{atomic access}
-
-\end_inset
-
+\layout Standard
+In case of memory mapped I/O devices the keyword
+\emph on
+volatile
\emph default
- (i.e.
- the processor needs more than one instruction for the access and could
- be interrupted while accessing the variable) the interrupt must disabled
- during the access to avoid inconsistent data.
- Access to 16 or 32 bit variables is obviously not atomic on 8 bit CPUs
- and should be protected by disabling interrupts.
- You're not automatically on the safe side if you use 8 bit variables though.
- We need an example here: f.e.
- on the 8051 the harmless looking
-\begin_inset Quotes srd
-\end_inset
+ has to be used to tell the compiler that accesses might not be removed:
+\layout Verse
\family typewriter
-flags\SpecialChar ~
-|=\SpecialChar ~
-0x80;
-\family default
-
-\begin_inset Quotes sld
-\end_inset
+volatile
+\begin_inset LatexCommand \index{volatile}
- is not atomic if
-\family typewriter
-flags
-\family default
- resides in xdata.
- Setting
-\begin_inset Quotes srd
\end_inset
+ xdata
+\begin_inset LatexCommand \index{xdata (mcs51, ds390 storage class)}
-\family typewriter
-flags\SpecialChar ~
-|=\SpecialChar ~
-0x40;
-\family default
-
-\begin_inset Quotes sld
-\end_inset
-
- from within an interrupt routine might get lost if the interrupt occurs
- at the wrong time.
-
-\begin_inset Quotes sld
\end_inset
+ at
+\begin_inset LatexCommand \index{at}
-\family typewriter
-counter\SpecialChar ~
-+=\SpecialChar ~
-8;
-\family default
-
-\begin_inset Quotes srd
\end_inset
- is not atomic on the 8051 even if
-\family typewriter
-counter
-\family default
- is located in data memory.
- Bugs like these are hard to reproduce and can cause a lot of trouble.
-
+ 0x8000 unsigned char PORTA_8255;
\layout Standard
-A special note here, int (16 bit) and long (32 bit) integer division
-\begin_inset LatexCommand \index{Division}
-
-\end_inset
-
-, multiplication
-\begin_inset LatexCommand \index{Multiplication}
-
-\end_inset
-
- & modulus
-\begin_inset LatexCommand \index{Modulus}
-
-\end_inset
+For some architectures (mcs51) array accesses are more efficient if an (xdata/fa
+r) array
+\family typewriter
+\size footnotesize
- and floating-point
-\begin_inset LatexCommand \index{Floating point support}
+\begin_inset LatexCommand \index{Aligned array}
\end_inset
- operations are implemented using external support routines developed in
- ANSI-C.
- If an interrupt service routine needs to do any of these operations then
- the support routines (as mentioned in a following section) will have to
- be recompiled using the
-\emph on
- -
-\begin_inset ERT
-status Collapsed
-\layout Standard
+\family default
+\size default
+ starts at a block (256 byte) boundary
+\begin_inset LatexCommand \index{block boundary}
-\backslash
-/
\end_inset
--stack-auto
-\begin_inset LatexCommand \index{-\/-stack-auto}
+ (section
+\begin_inset LatexCommand \ref{sub:A-Step-by Assembler Introduction}
\end_inset
+ has an example).
+\newline
+Absolute addresses can be specified for variables in all storage classes,
+ e.g.:
+\layout Verse
-\emph default
- option and the source file will need to be compiled using the
-\emph on
--
-\begin_inset ERT
-status Collapsed
-\layout Standard
+\family typewriter
+bit
+\begin_inset LatexCommand \index{bit}
-\backslash
-/
\end_inset
--int-long-reent
-\emph default
-
-\begin_inset LatexCommand \index{-\/-int-long-reent}
+ at
+\begin_inset LatexCommand \index{at}
\end_inset
- compiler option.
+ 0x02 bvar;
\layout Standard
-Calling other functions from an interrupt service routine is not recommended,
- avoid it if possible.
- Note that when some function is called from an interrupt service routine
- it should be preceded by a #pragma\SpecialChar ~
-NOOVERLAY
-\begin_inset LatexCommand \index{\#pragma NOOVERLAY}
-
-\end_inset
+The above example will allocate the variable at offset 0x02 in the bit-addressab
+le space.
+ There is no real advantage to assigning absolute addresses to variables
+ in this manner, unless you want strict control over all the variables allocated.
+ One possible use would be to write hardware portable code.
+ For example, if you have a routine that uses one or more of the microcontroller
+ I/O pins, and such pins are different for two different hardwares, you
+ can declare the I/O pins in your routine using:
+\layout Verse
- if it is not reentrant.
- Furthermore nonreentrant functions should not be called from the main program
- while the interrupt service routine might be active.
-
-\newline
-\newline
-Also see section
-\begin_inset LatexCommand \ref{sub:Overlaying}
+\family typewriter
+extern volatile
+\begin_inset LatexCommand \index{volatile}
\end_inset
+ bit MOSI;\SpecialChar ~
\SpecialChar ~
-about Overlaying and section
-\begin_inset LatexCommand \ref{sub:Functions-using-private-banks}
-
-\end_inset
-
\SpecialChar ~
-about Functions using private banks.
-\layout Section
-
-Enabling and Disabling Interrupts
-\layout Subsection
-
-Critical Functions and Critical Statements
-\layout Standard
-
-A special keyword may be associated with a function declaring it as
-\emph on
-critical
-\emph default
-.
- SDCC will generate code to disable all interrupts
-\begin_inset LatexCommand \index{interrupt}
-
-\end_inset
-
- upon entry to a critical function and restore the interrupt enable to the
- previous state before returning.
- Nesting critical functions will need one additional byte on the stack
-\begin_inset LatexCommand \index{stack}
-
-\end_inset
-
- for each call.
-\layout Verse
-
-
-\family typewriter
-int foo () critical
-\begin_inset LatexCommand \index{critical}
-
-\end_inset
+\SpecialChar ~
+/* master out, slave in */
+\newline
+extern volatile bit MISO;\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+/* master in, slave out */
+\newline
+extern volatile bit MCLK;\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+/* master clock */
+\newline
-
+\newline
+/* Input and Output of a byte on a 3-wire serial bus.
+\newline
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+If needed adapt polarity of clock, polarity of data and bit order
+\newline
+\SpecialChar ~
+*/
+\newline
+unsigned char spi_io(unsigned char out_byte)
\newline
{
\newline
\SpecialChar ~
\SpecialChar ~
\SpecialChar ~
-...
-
+unsigned char i=8;
\newline
\SpecialChar ~
\SpecialChar ~
\SpecialChar ~
\SpecialChar ~
-...
-
+do {
\newline
-}
-\layout Standard
-
-The critical attribute maybe used with other attributes like
-\emph on
-reentrant.
-\emph default
-
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+MOSI = out_byte & 0x80;
\newline
-The keyword
-\emph on
-critical
-\emph default
- may also be used to disable interrupts more locally:
-\layout Verse
-
-
-\family typewriter
-critical{ i++; }
-\layout Standard
-
-More than one statement could have been included in the block.
-\layout Subsection
-
-Enabling and Disabling Interrupts directly
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+out_byte <<= 1;
+\newline
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+MCLK = 1;
+\newline
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+/* _asm nop _endasm; */\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+/* for slow peripherals */
+\newline
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+if(MISO)
+\newline
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+out_byte += 1;
+\newline
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+MCLK = 0;
+\newline
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+} while(--i);
+\newline
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+return out_byte;
+\newline
+}
\layout Standard
-Interrupts
-\begin_inset LatexCommand \index{interrupt}
-
-\end_inset
-
- can also be disabled and enabled directly (8051):
-\layout Verse
-
-
-\family typewriter
-EA = 0;
-\layout Verse
-
-
-\family typewriter
-...
+Then, someplace in the code for the first hardware you would use
\layout Verse
\family typewriter
-EA = 1;
-\layout Standard
-
-On other architectures which have seperate opcodes for enabling and disabling
- interrupts you might want to make use of defines with inline assembly
-\begin_inset LatexCommand \index{Assembler routines}
+bit at
+\begin_inset LatexCommand \index{at}
\end_inset
- (HC08):
-\layout Verse
-
-\family typewriter
-#define CLI _asm
-\begin_inset LatexCommand \index{\_asm}
+\begin_inset LatexCommand \index{\_\_at}
\end_inset
+ 0x80 MOSI;\SpecialChar ~
\SpecialChar ~
\SpecialChar ~
-cli\SpecialChar ~
\SpecialChar ~
-_endasm
-\begin_inset LatexCommand \index{\_endasm}
-
-\end_inset
+/* I/O port 0, bit 0 */
+\newline
+bit at 0x81 MISO;\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+/* I/O port 0, bit 1 */
+\newline
+bit at 0x82 MCLK;\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+/* I/O port 0, bit 2 */
+\layout Standard
-;
+Similarly, for the second hardware you would use
\layout Verse
\family typewriter
-#define SEI _asm\SpecialChar ~
+bit at 0x83 MOSI;\SpecialChar ~
\SpecialChar ~
-sei\SpecialChar ~
\SpecialChar ~
-_endasm;
-\layout Verse
+\SpecialChar ~
+/* I/O port 0, bit 3 */
+\newline
+bit at 0x91 MISO;\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+/* I/O port 1, bit 1 */
+\newline
+bit
+\begin_inset LatexCommand \index{bit}
+\end_inset
-\family typewriter
-...
+ at 0x92 MCLK;\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+/* I/O port 1, bit 2 */
\layout Standard
-Note: it is sometimes sufficient to disable only a specific interrupt source
- like f.e.
- a timer or serial interrupt by manipulating an
-\emph on
-interrupt mask
-\begin_inset LatexCommand \index{interrupt mask}
+and you can use the same hardware dependent routine without changes, as
+ for example in a library.
+ This is somehow similar to sbit, but only one absolute address has to be
+ specified in the whole project.
+\layout Section
+
+Parameters
+\begin_inset LatexCommand \index{Parameters}
\end_inset
-\emph default
- register.
- Usually the time during which interrupts are disabled should be kept as
- short as possible.
- This minimizes both
-\emph on
-interrupt latency
-\emph default
+\begin_inset LatexCommand \index{function parameter}
-\begin_inset LatexCommand \index{interrupt latency}
+\end_inset
+
+ & Local Variables
+\begin_inset LatexCommand \index{local variables}
\end_inset
- (the time between the occurrence of the interrupt and the execution of
- the first code in the interrupt routine) and
-\emph on
-interrupt jitter
-\emph default
-\begin_inset LatexCommand \index{interrupt jitter}
+\begin_inset LatexCommand \label{sec:Parameters-and-Local-Variables}
\end_inset
- (the difference between the shortest and the longest interrupt latency).
- These really are something different, f.e.
- a serial interrupt has to be served before its buffer overruns so it cares
- for the maximum interrupt latency, whereas it does not care about jitter.
- On a loudspeaker driven via a digital to analog converter which is fed
- by an interrupt a latency of a few milliseconds might be tolerable, whereas
- a much smaller jitter will be very audible.
+
\layout Standard
-You can reenable interrupts within an interrupt routine and on some architecture
-s you can make use of two (or more) levels of
+Automatic (local) variables and parameters to functions can either be placed
+ on the stack or in data-space.
+ The default action of the compiler is to place these variables in the internal
+ RAM (for small model) or external RAM (for large model).
+ This in fact makes them similar to
\emph on
-interrupt priorities
-\emph default
-
-\begin_inset LatexCommand \index{interrupt priority}
+static
+\begin_inset LatexCommand \index{static}
\end_inset
-.
- On architectures which don't support interrupt priorities these can be
- implemented by manipulating the interrupt mask and reenabling interrupts
- within the interrupt routine.
- Don't add complexity unless you have to.
-
-\layout Section
-Functions using private banks
-\begin_inset LatexCommand \label{sub:Functions-using-private-banks}
+\emph default
+ so by default functions are non-reentrant
+\begin_inset LatexCommand \index{reentrant}
\end_inset
+.
+
+\newline
-\begin_inset LatexCommand \index{bank}
+\newline
+They can be placed on the stack
+\begin_inset LatexCommand \index{stack}
\end_inset
+ by using the
+\emph on
+ -
+\begin_inset ERT
+status Collapsed
\layout Standard
-The
-\emph on
-using
-\begin_inset LatexCommand \index{using}
-
+\backslash
+/
\end_inset
-
-\emph default
- attribute (which tells the compiler to use a register bank other than the
- default bank zero) should only be applied to
-\emph on
-interrupt
-\begin_inset LatexCommand \index{interrupt}
+-stack-auto
+\begin_inset LatexCommand \index{-\/-stack-auto}
\end_inset
\emph default
- functions (see note 1 below).
- This will in most circumstances make the generated ISR code more efficient
- since it will not have to save registers on the stack.
-\layout Standard
-
-The
-\emph on
-using
-\emph default
- attribute will have no effect on the generated code for a
+ option, by using
\emph on
-non-interrupt
+#pragma\SpecialChar ~
+stackauto
\emph default
- function (but may occasionally be useful anyway
-\begin_inset Foot
-collapsed false
-\layout Standard
+\begin_inset LatexCommand \index{\#pragma stackauto}
-possible exception: if a function is called ONLY from 'interrupt' functions
- using a particular bank, it can be declared with the same 'using' attribute
- as the calling 'interrupt' functions.
- For instance, if you have several ISRs using bank one, and all of them
- call memcpy(), it might make sense to create a specialized version of memcpy()
- 'using 1', since this would prevent the ISR from having to save bank zero
- to the stack on entry and switch to bank zero before calling the function
\end_inset
-).
-\newline
-
+ or by using the
\emph on
-(pending: I don't think this has been done yet)
-\layout Standard
-
-An
-\emph on
-interrupt
-\emph default
- function using a non-zero bank will assume that it can trash that register
- bank, and will not save it.
- Since high-priority interrupts
-\begin_inset LatexCommand \index{interrupt priority}
+reentrant
+\begin_inset LatexCommand \index{reentrant}
\end_inset
- can interrupt low-priority ones on the 8051 and friends, this means that
- if a high-priority ISR
-\emph on
-using
+
\emph default
- a particular bank occurs while processing a low-priority ISR
+ keyword in the function declaration, e.g.:
+\layout Verse
+
+
+\family typewriter
+unsigned char foo(char i) reentrant
+\newline
+{
+\newline
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+...
+
+\newline
+}
+\layout Standard
+
+Since stack space on 8051 is limited, the
\emph on
-using
+reentrant
\emph default
- the same bank, terrible and bad things can happen.
- To prevent this, no single register bank should be
+keyword or the
\emph on
-used
-\emph default
- by both a high priority and a low priority ISR.
- This is probably most easily done by having all high priority ISRs use
- one bank and all low priority ISRs use another.
- If you have an ISR which can change priority at runtime, you're on your
- own: I suggest using the default bank zero and taking the small performance
- hit.
+ -
+\begin_inset ERT
+status Collapsed
+
\layout Standard
-It is most efficient if your ISR calls no other functions.
- If your ISR must call other functions, it is most efficient if those functions
- use the same bank as the ISR (see note 1 below); the next best is if the
- called functions use bank zero.
- It is very inefficient to call a function using a different, non-zero bank
- from an ISR.
-
-\layout Section
+\backslash
+/
+\end_inset
-Startup Code
-\begin_inset LatexCommand \label{sub:Startup-Code}
+-stack-auto
+\emph default
+ option should be used sparingly.
+ Note that the reentrant keyword just means that the parameters & local
+ variables will be allocated to the stack, it
+\emph on
+does not
+\emph default
+ mean that the function is register bank
+\begin_inset LatexCommand \index{register bank (mcs51, ds390)}
\end_inset
+ independent.
+\newline
-\begin_inset LatexCommand \index{Startup code}
+\newline
+Local variables
+\begin_inset LatexCommand \index{local variables}
\end_inset
+ can be assigned storage classes and absolute
+\begin_inset LatexCommand \index{Absolute addressing}
-\layout Subsection
+\end_inset
-MCS51/DS390 Startup Code
-\layout Standard
+ addresses, e.g.:
+\layout Verse
-The compiler inserts a call to the C routine
-\emph on
-_sdcc_external_startup()
-\begin_inset LatexCommand \index{\_sdcc\_external\_startup()}
-\end_inset
+\family typewriter
+unsigned char foo()
+\newline
+{
+\newline
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+xdata unsigned char i;
+\newline
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+bit bvar;
+\newline
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+data at
+\begin_inset LatexCommand \index{at}
+\end_inset
-\series bold
-\emph default
+ 0x31 unsigned char j;
+\newline
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+...
-\series default
-at the start of the CODE area.
- This routine is in the runtime library
-\begin_inset LatexCommand \index{Runtime library}
-
-\end_inset
+\newline
+}
+\layout Standard
-.
- By default this routine returns 0, if this routine returns a non-zero value,
- the static & global variable initialization will be skipped and the function
- main will be invoked.
- Otherwise static & global variables will be initialized before the function
- main is invoked.
- You could add a
+In the above example the variable
\emph on
-_sdcc_external_startup()
+i
\emph default
- routine to your program to override the default if you need to setup hardware
- or perform some other critical operation prior to static & global variable
- initialization.
- On some mcs51 variants xdata has to be explicitly enabled before it can
- be accessed, this is the place to do it.
- See also the compiler option
+ will be allocated in the external ram,
+\emph on
+bvar
+\emph default
+ in bit addressable space and
+\emph on
+ j
+\emph default
+ in internal ram.
+ When compiled with
\emph on
-
\begin_inset ERT
/
\end_inset
--no-xinit
+-stack-auto
\emph default
--
+ or when a function is declared as
\emph on
-opt
+reentrant
\emph default
+ this should only be done for static variables.
+\layout Standard
-\begin_inset LatexCommand \index{-\/-no-xinit-opt}
+Parameters
+\begin_inset LatexCommand \index{function parameter}
\end_inset
- and section
-\begin_inset LatexCommand \ref{sub:MCS51-variants}
+ however are not allowed any storage class
+\begin_inset LatexCommand \index{Storage class}
\end_inset
-\SpecialChar ~
-about MCS51-variants.
-\layout Subsection
-
-HC08 Startup Code
+, (storage classes for parameters will be ignored), their allocation is
+ governed by the memory model in use, and the reentrancy options.
\layout Standard
-The HC08 startup code follows the same scheme as the MCS51 startup code.
-\layout Subsection
+It is however allowed to use bit parameters in reentrant functions and also
+ non-static local bit variables are supported.
+ Efficient use is limited to 8 semi-bitregisters in bit space.
+ They are pushed and popped to stack as a single byte just like the normal
+ registers.
+\layout Section
-Z80 Startup Code
-\layout Standard
+Overlaying
+\begin_inset LatexCommand \label{sub:Overlaying}
-On the Z80 the startup code is inserted by linking with crt0.o which is generated
- from sdcc/device/lib/z80/crt0.s.
- If you need a different startup code you can use the compiler option
-\emph on
--
-\series bold
-\emph default
+\end_inset
+
+
+\begin_inset LatexCommand \index{Overlaying}
+
+\end_inset
-\begin_inset ERT
-status Collapsed
\layout Standard
-\backslash
-/
+For non-reentrant
+\begin_inset LatexCommand \index{reentrant}
+
\end_inset
+ functions SDCC will try to reduce internal ram space usage by overlaying
+ parameters and local variables of a function (if possible).
+ Parameters and local variables
+\begin_inset LatexCommand \index{local variables}
-\series default
-\emph on
--no-std-crt0
-\emph default
+\end_inset
-\begin_inset LatexCommand \index{-\/-no-std-crt0}
+ of a function will be allocated to an overlayable segment if the function
+ has
+\emph on
+no other function calls and the function is non-reentrant and the memory
+ model
+\begin_inset LatexCommand \index{Memory model}
\end_inset
- and provide your own crt0.o.
-
-\layout Section
+ is small.
-Inline Assembler Code
-\begin_inset LatexCommand \index{Assembler routines}
+\emph default
+ If an explicit storage class
+\begin_inset LatexCommand \index{Storage class}
\end_inset
+ is specified for a local variable, it will NOT be overlayed.
+\layout Standard
-\layout Subsection
+Note that the compiler (not the linkage editor) makes the decision for overlayin
+g the data items.
+ Functions that are called from an interrupt service routine should be preceded
+ by a #pragma\SpecialChar ~
+nooverlay
+\begin_inset LatexCommand \index{\#pragma nooverlay}
-A Step by Step Introduction
+\end_inset
+
+ if they are not reentrant.
\layout Standard
-Starting from a small snippet of c-code this example shows for the MCS51
- how to use inline assembly, access variables, a function parameter and
- an array in xdata memory.
- This is a buffer routine which should be optimized:
-\layout Verse
+Also note that the compiler does not do any processing of inline assembler
+ code, so the compiler might incorrectly assign local variables and parameters
+ of a function into the overlay segment if the inline assembler code calls
+ other c-functions that might use the overlay.
+ In that case the #pragma\SpecialChar ~
+nooverlay should be used.
+\layout Standard
+Parameters and local variables of functions that contain 16 or 32 bit multiplica
+tion
+\begin_inset LatexCommand \index{Multiplication}
-\family typewriter
-\size footnotesize
-unsigned char xdata at 0x7f00 buf[0x100];
-\newline
-unsigned char head,tail;
-\newline
+\end_inset
-\newline
-void to_buffer( unsigned char c )
-\newline
-{
-\newline
-\SpecialChar ~
-\SpecialChar ~
-\SpecialChar ~
-\SpecialChar ~
-if( head != tail-1 )
-\newline
-\SpecialChar ~
-\SpecialChar ~
-\SpecialChar ~
-\SpecialChar ~
-\SpecialChar ~
-\SpecialChar ~
-\SpecialChar ~
-\SpecialChar ~
-buf[ head++ ] = c;
-\newline
-}
-\layout Standard
-
-If the code snippet (assume it is saved in buffer.c) is compiled with SDCC
- then a corresponding buffer.asm file is generated.
- We define a new function
-\family typewriter
-to_buffer_asm()
-\family default
- in file buffer.c in which we cut and paste the generated code, removing
- unwanted comments and some ':'.
- Then add
-\begin_inset Quotes sld
-\end_inset
-
-_asm
-\begin_inset Quotes srd
-\end_inset
-
- and
-\begin_inset Quotes sld
-\end_inset
+ or division
+\begin_inset LatexCommand \index{Division}
-_endasm;
-\begin_inset Quotes srd
\end_inset
- to the beginning and the end of the function body:
+ will NOT be overlayed since these are implemented using external functions,
+ e.g.:
\layout Verse
\family typewriter
-\size footnotesize
-/* With a cut and paste from the .asm file, we have something to start with.
-\newline
-\SpecialChar ~
-\SpecialChar ~
-\SpecialChar ~
-The function is not yet OK! (registers aren't saved) */
-\newline
-void to_buffer_asm( unsigned char c )
-\newline
-{
+#pragma save
\newline
-\SpecialChar ~
-\SpecialChar ~
-\SpecialChar ~
-\SpecialChar ~
-_asm
-\begin_inset LatexCommand \index{\_asm}
+#pragma nooverlay
+\begin_inset LatexCommand \index{\#pragma nooverlay}
\end_inset
-
-\newline
-\SpecialChar ~
-\SpecialChar ~
-\SpecialChar ~
-\SpecialChar ~
-mov\SpecialChar ~
-\SpecialChar ~
-r2,dpl
-\newline
-;buffer.c if( head != tail-1 )
-\newline
-\SpecialChar ~
-\SpecialChar ~
-\SpecialChar ~
-\SpecialChar ~
-mov\SpecialChar ~
-\SpecialChar ~
-a,_tail
-\newline
-\SpecialChar ~
-\SpecialChar ~
-\SpecialChar ~
-\SpecialChar ~
-dec\SpecialChar ~
-\SpecialChar ~
-a
-\newline
-\SpecialChar ~
-\SpecialChar ~
-\SpecialChar ~
-\SpecialChar ~
-mov\SpecialChar ~
-\SpecialChar ~
-r3,a
-\newline
-\SpecialChar ~
-\SpecialChar ~
-\SpecialChar ~
-\SpecialChar ~
-mov\SpecialChar ~
-\SpecialChar ~
-a,_head
-\newline
-\SpecialChar ~
-\SpecialChar ~
-\SpecialChar ~
-\SpecialChar ~
-cjne a,ar3,00106$
-\newline
-ret 00106$:
-\newline
-;buffer.c buf[ head++ ] = c;
-\newline
-\SpecialChar ~
-\SpecialChar ~
-\SpecialChar ~
-\SpecialChar ~
-mov\SpecialChar ~
-\SpecialChar ~
-r3,_head
+
\newline
-\SpecialChar ~
-\SpecialChar ~
-\SpecialChar ~
-\SpecialChar ~
-inc\SpecialChar ~
-\SpecialChar ~
-_head
+void set_error(unsigned char errcd)
\newline
-\SpecialChar ~
-\SpecialChar ~
-\SpecialChar ~
-\SpecialChar ~
-mov\SpecialChar ~
-\SpecialChar ~
-a,r3
+{
\newline
\SpecialChar ~
\SpecialChar ~
\SpecialChar ~
\SpecialChar ~
-add\SpecialChar ~
-\SpecialChar ~
-a,#_buf
+P3 = errcd;
\newline
-\SpecialChar ~
-\SpecialChar ~
-\SpecialChar ~
-\SpecialChar ~
-mov\SpecialChar ~
-\SpecialChar ~
-dpl,a
+}
\newline
-\SpecialChar ~
-\SpecialChar ~
-\SpecialChar ~
-\SpecialChar ~
-clr\SpecialChar ~
-\SpecialChar ~
-a
+#pragma restore
\newline
-\SpecialChar ~
-\SpecialChar ~
-\SpecialChar ~
-\SpecialChar ~
-addc\SpecialChar ~
-a,#(_buf >> 8)
+
\newline
-\SpecialChar ~
-\SpecialChar ~
-\SpecialChar ~
-\SpecialChar ~
-mov\SpecialChar ~
-\SpecialChar ~
-dph,a
+void some_isr () interrupt
+\begin_inset LatexCommand \index{interrupt}
+
+\end_inset
+
+ 2
\newline
-\SpecialChar ~
-\SpecialChar ~
-\SpecialChar ~
-\SpecialChar ~
-mov\SpecialChar ~
-\SpecialChar ~
-a,r2
+{
\newline
\SpecialChar ~
\SpecialChar ~
\SpecialChar ~
\SpecialChar ~
-movx @dptr,a
-\newline
-00103$:
+...
\newline
\SpecialChar ~
\SpecialChar ~
\SpecialChar ~
\SpecialChar ~
-ret
+set_error(10);
\newline
\SpecialChar ~
\SpecialChar ~
\SpecialChar ~
\SpecialChar ~
-_endasm;
+...
+
\newline
-}
+}
\layout Standard
-The new file buffer.c should compile with only one warning about the unreferenced
- function argument 'c'.
- Now we hand-optimize the assembly code and insert an #define USE_ASSEMBLY
- and finally have:
+In the above example the parameter
+\emph on
+errcd
+\emph default
+ for the function
+\emph on
+set_error
+\emph default
+ would be assigned to the overlayable segment if the #pragma\SpecialChar ~
+nooverlay was
+ not present, this could cause unpredictable runtime behavior when called
+ from an interrupt service routine.
+ The #pragma\SpecialChar ~
+nooverlay ensures that the parameters and local variables for
+ the function are NOT overlayed.
+\layout Section
+
+Interrupt Service Routines
+\begin_inset LatexCommand \label{sub:Interrupt-Service-Routines}
+
+\end_inset
+
+
+\layout Subsection
+
+General Information
+\layout Standard
+
+SDCC allows
+\emph on
+i
+\emph default
+nterrupt
+\emph on
+s
+\emph default
+ervice
+\emph on
+r
+\emph default
+outines to be coded in C, with some extended keywords.
\layout Verse
\family typewriter
-\size footnotesize
-unsigned char xdata at 0x7f00 buf[0x100];
-\newline
-unsigned char head,tail;
-\newline
-#define USE_ASSEMBLY
-\newline
-
-\newline
-#ifndef USE_ASSEMBLY
-\newline
-void to_buffer( unsigned char c )
-\newline
-{
+void timer_isr (void) interrupt 1 using 1
\newline
-\SpecialChar ~
-\SpecialChar ~
-\SpecialChar ~
-\SpecialChar ~
-if( head != tail-1 )
+{
\newline
\SpecialChar ~
\SpecialChar ~
\SpecialChar ~
\SpecialChar ~
-\SpecialChar ~
-\SpecialChar ~
-\SpecialChar ~
-\SpecialChar ~
-buf[ head++ ] = c;
+...
+
\newline
}
-\newline
+\layout Standard
-\newline
-#else
-\newline
-
-\newline
-void to_buffer( unsigned char c )
-\newline
-{
-\newline
-\SpecialChar ~
-\SpecialChar ~
-\SpecialChar ~
-\SpecialChar ~
-c; // to avoid warning: unreferenced function argument
-\newline
-\SpecialChar ~
-\SpecialChar ~
-\SpecialChar ~
-\SpecialChar ~
-_asm
-\begin_inset LatexCommand \index{\_asm}
+The optional number following the
+\emph on
+interrupt
+\begin_inset LatexCommand \index{interrupt}
\end_inset
-\newline
-\SpecialChar ~
-\SpecialChar ~
-\SpecialChar ~
-\SpecialChar ~
-\SpecialChar ~
-\SpecialChar ~
-\SpecialChar ~
-\SpecialChar ~
-; save used registers here.
-
-\newline
-\SpecialChar ~
-\SpecialChar ~
-\SpecialChar ~
-\SpecialChar ~
-\SpecialChar ~
-\SpecialChar ~
-\SpecialChar ~
-\SpecialChar ~
-; If we were still using r2,r3 we would have to push them here.
-
-\newline
-; if( head != tail-1 )
-\newline
-\SpecialChar ~
-\SpecialChar ~
-\SpecialChar ~
-\SpecialChar ~
-\SpecialChar ~
-\SpecialChar ~
-\SpecialChar ~
-\SpecialChar ~
-mov\SpecialChar ~
- a,_tail
-\newline
-\SpecialChar ~
-\SpecialChar ~
-\SpecialChar ~
-\SpecialChar ~
-\SpecialChar ~
-\SpecialChar ~
-\SpecialChar ~
-\SpecialChar ~
-dec\SpecialChar ~
- a
-\newline
-\SpecialChar ~
-\SpecialChar ~
-\SpecialChar ~
-\SpecialChar ~
-\SpecialChar ~
-\SpecialChar ~
-\SpecialChar ~
-\SpecialChar ~
-xrl\SpecialChar ~
- a,_head
-\newline
-\SpecialChar ~
-\SpecialChar ~
-\SpecialChar ~
-\SpecialChar ~
-\SpecialChar ~
-\SpecialChar ~
-\SpecialChar ~
-\SpecialChar ~
-; we could do an ANL a,#0x0f here to use a smaller buffer (see below)
-\newline
-\SpecialChar ~
-\SpecialChar ~
-\SpecialChar ~
-\SpecialChar ~
-\SpecialChar ~
-\SpecialChar ~
-\SpecialChar ~
-\SpecialChar ~
-jz\SpecialChar ~
-\SpecialChar ~
- t_b_end$
-\newline
-\SpecialChar ~
-\SpecialChar ~
-\SpecialChar ~
-\SpecialChar ~
-\SpecialChar ~
-\SpecialChar ~
-\SpecialChar ~
-\SpecialChar ~
-;
-\newline
-; buf[ head++ ] = c;
-\newline
-\SpecialChar ~
-\SpecialChar ~
-\SpecialChar ~
-\SpecialChar ~
-\SpecialChar ~
-\SpecialChar ~
-\SpecialChar ~
-\SpecialChar ~
-mov\SpecialChar ~
- a,dpl \SpecialChar ~
-\SpecialChar ~
-\SpecialChar ~
-\SpecialChar ~
-\SpecialChar ~
-\SpecialChar ~
-\SpecialChar ~
-; dpl holds lower byte of function argument
-\newline
-\SpecialChar ~
-\SpecialChar ~
-\SpecialChar ~
-\SpecialChar ~
-\SpecialChar ~
-\SpecialChar ~
-\SpecialChar ~
-\SpecialChar ~
-mov\SpecialChar ~
- dpl,_head \SpecialChar ~
-\SpecialChar ~
-\SpecialChar ~
-; buf is 0x100 byte aligned so head can be used directly
-\newline
-\SpecialChar ~
-\SpecialChar ~
-\SpecialChar ~
-\SpecialChar ~
-\SpecialChar ~
-\SpecialChar ~
-\SpecialChar ~
-\SpecialChar ~
-mov\SpecialChar ~
- dph,#(_buf>>8)
-\newline
-\SpecialChar ~
-\SpecialChar ~
-\SpecialChar ~
-\SpecialChar ~
-\SpecialChar ~
-\SpecialChar ~
-\SpecialChar ~
-\SpecialChar ~
-movx @dptr,a
-\newline
-\SpecialChar ~
-\SpecialChar ~
-\SpecialChar ~
-\SpecialChar ~
-\SpecialChar ~
-\SpecialChar ~
-\SpecialChar ~
-\SpecialChar ~
-inc \SpecialChar ~
-_head
-\newline
-\SpecialChar ~
-\SpecialChar ~
-\SpecialChar ~
-\SpecialChar ~
-\SpecialChar ~
-\SpecialChar ~
-\SpecialChar ~
-\SpecialChar ~
-; we could do an ANL _head,#0x0f here to use a smaller buffer (see above)
-\newline
-t_b_end$:
-\newline
-\SpecialChar ~
-\SpecialChar ~
-\SpecialChar ~
-\SpecialChar ~
-\SpecialChar ~
-\SpecialChar ~
-\SpecialChar ~
-\SpecialChar ~
-; restore used registers here
-\newline
-\SpecialChar ~
-\SpecialChar ~
-\SpecialChar ~
-\SpecialChar ~
-_endasm;
-\newline
-}
-\newline
-#endif
-\layout Standard
-
-The inline assembler code can contain any valid code understood by the assembler
-, this includes any assembler directives and comment lines
-\begin_inset Foot
-collapsed false
-
-\layout Standard
+\begin_inset LatexCommand \index{\_\_interrupt}
-The assembler does not like some characters like ':' or ''' in comments.
\end_inset
+
+\emph default
+ keyword is the interrupt number this routine will service.
+ When present, the compiler will insert a call to this routine in the interrupt
+ vector table for the interrupt number specified.
+ If you have multiple source files in your project, interrupt service routines
+ can be present in any of them, but a prototype of the isr MUST be present
+ or included in the file that contains the function
+\emph on
+main
+\emph default
.
- The compiler does not do any validation of the code within the
-\family typewriter
-_asm
-\begin_inset LatexCommand \index{\_asm}
+ The optional
+\emph on
+using
+\begin_inset LatexCommand \index{using (mcs51, ds390 register bank)}
\end_inset
- ...
- _endasm;
-\family default
- keyword pair.
- Specifically it will not know which registers are used and thus register
- pushing/popping
-\begin_inset LatexCommand \index{push/pop}
+
+\begin_inset LatexCommand \index{\_\_using (mcs51, ds390 register bank)}
\end_inset
- has to be done manually.
-
-\layout Standard
-It is strongly recommended that each assembly instruction (including labels)
- be placed in a separate line (as the example shows).
- When the -
-\begin_inset ERT
-status Collapsed
+\emph default
+ keyword can be used to tell the compiler to use the specified register
+ bank (8051 specific) when generating code for this function.
+
+\newline
\layout Standard
-\backslash
-/
+Interrupt service routines open the door for some very interesting bugs:
+\newline
+If an interrupt service routine changes variables which are accessed by
+ other functions these variables have to be declared
+\emph on
+volatile
+\emph default
+
+\begin_inset LatexCommand \index{volatile}
+
\end_inset
--
+.
+
+\layout Standard
+
+If the access to these variables is not
\emph on
-peep-asm
-\begin_inset LatexCommand \index{-\/-peep-asm}
+atomic
+\begin_inset LatexCommand \index{atomic}
\end_inset
\emph default
- command line option is used, the inline assembler code will be passed through
- the peephole optimizer
-\begin_inset LatexCommand \index{Peephole optimizer}
-
+ (i.e.
+ the processor needs more than one instruction for the access and could
+ be interrupted while accessing the variable) the interrupt must be disabled
+ during the access to avoid inconsistent data.
+ Access to 16 or 32 bit variables is obviously not atomic on 8 bit CPUs
+ and should be protected by disabling interrupts.
+ You're not automatically on the safe side if you use 8 bit variables though.
+ We need an example here: f.e.
+ on the 8051 the harmless looking
+\begin_inset Quotes srd
\end_inset
-.
- There are only a few (if any) cases where this option makes sense, it might
- cause some unexpected changes in the inline assembler code.
- Please go through the peephole optimizer rules defined in file
-\emph on
-SDCCpeeph.def
-\emph default
- carefully before using this option.
-\layout Subsection
-Naked Functions
-\begin_inset LatexCommand \label{sub:Naked-Functions}
+\family typewriter
+flags\SpecialChar ~
+|=\SpecialChar ~
+0x80;
+\family default
+\begin_inset Quotes sld
+\end_inset
+
+ is not atomic if
+\family typewriter
+flags
+\family default
+ resides in xdata.
+ Setting
+\begin_inset Quotes srd
\end_inset
-\begin_inset LatexCommand \index{Naked functions}
+\family typewriter
+flags\SpecialChar ~
+|=\SpecialChar ~
+0x40;
+\family default
+\begin_inset Quotes sld
+\end_inset
+
+ from within an interrupt routine might get lost if the interrupt occurs
+ at the wrong time.
+
+\begin_inset Quotes sld
\end_inset
+\family typewriter
+counter\SpecialChar ~
++=\SpecialChar ~
+8;
+\family default
+
+\begin_inset Quotes srd
+\end_inset
+
+ is not atomic on the 8051 even if
+\family typewriter
+counter
+\family default
+ is located in data memory.
+ Bugs like these are hard to reproduce and can cause a lot of trouble.
+
\layout Standard
-A special keyword may be associated with a function declaring it as
-\emph on
-_naked
-\begin_inset LatexCommand \index{\_naked}
+The return address and the registers used in the interrupt service routine
+ are saved on the stack
+\begin_inset LatexCommand \index{stack}
\end_inset
-.
-
-\emph default
-The
+ so there must be sufficient stack space.
+ If there isn't variables or registers (or even the return address itself)
+ will be corrupted.
+ This
\emph on
-_naked
+stack overflow
\emph default
- function modifier attribute prevents the compiler from generating prologue
-\begin_inset LatexCommand \index{function prologue}
+
+\begin_inset LatexCommand \index{stack overflow}
\end_inset
- and epilogue
-\begin_inset LatexCommand \index{function epilogue}
+ is most likely to happen if the interrupt occurs during the
+\begin_inset Quotes sld
+\end_inset
+deepest
+\begin_inset Quotes srd
\end_inset
- code for that function.
- This means that the user is entirely responsible for such things as saving
- any registers that may need to be preserved, selecting the proper register
- bank, generating the
-\emph on
-return
-\emph default
- instruction at the end, etc.
- Practically, this means that the contents of the function must be written
- in inline assembler.
- This is particularly useful for interrupt functions, which can have a large
- (and often unnecessary) prologue/epilogue.
- For example, compare the code generated by these two functions:
-\layout Verse
+ subroutine when the stack is already in use for f.e.
+ many return addresses.
+\layout Standard
+A special note here, int (16 bit) and long (32 bit) integer division
+\begin_inset LatexCommand \index{Division}
-\family typewriter
-volatile
-\begin_inset LatexCommand \index{volatile}
+\end_inset
+
+, multiplication
+\begin_inset LatexCommand \index{Multiplication}
\end_inset
- data unsigned char counter;
-\newline
+ & modulus
+\begin_inset LatexCommand \index{Modulus}
-\newline
-void simpleInterrupt(void) interrupt
-\begin_inset LatexCommand \index{interrupt}
+\end_inset
+
+ and floating-point
+\begin_inset LatexCommand \index{Floating point support}
\end_inset
- 1
-\newline
-{
-\newline
-\SpecialChar ~
-\SpecialChar ~
-\SpecialChar ~
-\SpecialChar ~
-counter++;
-\newline
-}
-\newline
+ operations are implemented using external support routines developed in
+ ANSI-C.
+ If an interrupt service routine needs to do any of these operations then
+ the support routines (as mentioned in a following section) will have to
+ be recompiled using the
+\emph on
+ -
+\begin_inset ERT
+status Collapsed
-\newline
-void nakedInterrupt(void) interrupt 2 _naked
-\newline
-{
-\newline
-\SpecialChar ~
-\SpecialChar ~
-\SpecialChar ~
-\SpecialChar ~
-_asm
-\begin_inset LatexCommand \index{\_asm}
+\layout Standard
+\backslash
+/
\end_inset
+-stack-auto
+\begin_inset LatexCommand \index{-\/-stack-auto}
-\newline
-\SpecialChar ~
-\SpecialChar ~
-\SpecialChar ~
-\SpecialChar ~
-\SpecialChar ~
-\SpecialChar ~
-inc\SpecialChar ~
-\SpecialChar ~
-\SpecialChar ~
-\SpecialChar ~
-\SpecialChar ~
-_counter
-\newline
-\SpecialChar ~
-\SpecialChar ~
-\SpecialChar ~
-\SpecialChar ~
-\SpecialChar ~
-\SpecialChar ~
-reti\SpecialChar ~
-\SpecialChar ~
-\SpecialChar ~
-\SpecialChar ~
-; MUST explicitly include ret or reti in _naked function.
-\newline
-\SpecialChar ~
-\SpecialChar ~
-\SpecialChar ~
-\SpecialChar ~
-_endasm
-\begin_inset LatexCommand \index{\_endasm}
+\end_inset
+
+
+\emph default
+ option and the source file will need to be compiled using the
+\emph on
+-
+\begin_inset ERT
+status Collapsed
+
+\layout Standard
+\backslash
+/
\end_inset
-;
-\newline
-}
+-int-long-reent
+\emph default
+
+\begin_inset LatexCommand \index{-\/-int-long-reent}
+
+\end_inset
+
+ compiler option.
\layout Standard
-For an 8051 target, the generated simpleInterrupt looks like:
-\layout Verse
+Calling other functions from an interrupt service routine is not recommended,
+ avoid it if possible.
+ Note that when some function is called from an interrupt service routine
+ it should be preceded by a #pragma\SpecialChar ~
+nooverlay
+\begin_inset LatexCommand \index{\#pragma nooverlay}
+\end_inset
-\family typewriter
-_simpleInterrupt:
+ if it is not reentrant.
+ Furthermore nonreentrant functions should not be called from the main program
+ while the interrupt service routine might be active.
+ They also must not be called from low priority interrupt service routines
+ while a high priority interrupt service routine might be active.
+ You could use semaphores or make the function
+\emph on
+ critical
+\emph default
+ if all parameters are passed in registers.
\newline
+
+\newline
+Also see section
+\begin_inset LatexCommand \ref{sub:Overlaying}
+
+\end_inset
+
\SpecialChar ~
+about Overlaying and section
+\begin_inset LatexCommand \ref{sub:Functions-using-private-banks}
+
+\end_inset
+
\SpecialChar ~
-\SpecialChar ~
-\SpecialChar ~
-push\SpecialChar ~
-\SpecialChar ~
-\SpecialChar ~
-\SpecialChar ~
-acc
-\newline
-\SpecialChar ~
-\SpecialChar ~
-\SpecialChar ~
-\SpecialChar ~
-push\SpecialChar ~
-\SpecialChar ~
-\SpecialChar ~
-\SpecialChar ~
-b
-\newline
-\SpecialChar ~
-\SpecialChar ~
-\SpecialChar ~
-\SpecialChar ~
-push\SpecialChar ~
-\SpecialChar ~
-\SpecialChar ~
-\SpecialChar ~
-dpl
-\newline
-\SpecialChar ~
-\SpecialChar ~
-\SpecialChar ~
-\SpecialChar ~
-push\SpecialChar ~
-\SpecialChar ~
-\SpecialChar ~
-\SpecialChar ~
-dph
-\newline
-\SpecialChar ~
-\SpecialChar ~
-\SpecialChar ~
-\SpecialChar ~
-push\SpecialChar ~
-\SpecialChar ~
-\SpecialChar ~
-\SpecialChar ~
-psw
-\newline
-\SpecialChar ~
-\SpecialChar ~
-\SpecialChar ~
-\SpecialChar ~
-mov\SpecialChar ~
-\SpecialChar ~
-\SpecialChar ~
-\SpecialChar ~
-\SpecialChar ~
-psw,#0x00
-\newline
-\SpecialChar ~
-\SpecialChar ~
-\SpecialChar ~
-\SpecialChar ~
-inc\SpecialChar ~
-\SpecialChar ~
-\SpecialChar ~
-\SpecialChar ~
-\SpecialChar ~
-_counter
-\newline
-\SpecialChar ~
-\SpecialChar ~
-\SpecialChar ~
-\SpecialChar ~
-pop\SpecialChar ~
-\SpecialChar ~
-\SpecialChar ~
-\SpecialChar ~
-\SpecialChar ~
-psw
-\newline
-\SpecialChar ~
-\SpecialChar ~
-\SpecialChar ~
-\SpecialChar ~
-pop\SpecialChar ~
-\SpecialChar ~
-\SpecialChar ~
-\SpecialChar ~
-\SpecialChar ~
-dph
-\newline
-\SpecialChar ~
-\SpecialChar ~
-\SpecialChar ~
-\SpecialChar ~
-pop\SpecialChar ~
-\SpecialChar ~
-\SpecialChar ~
-\SpecialChar ~
-\SpecialChar ~
-dpl
-\newline
-\SpecialChar ~
-\SpecialChar ~
-\SpecialChar ~
-\SpecialChar ~
-pop\SpecialChar ~
-\SpecialChar ~
-\SpecialChar ~
-\SpecialChar ~
-\SpecialChar ~
-b
-\newline
-\SpecialChar ~
-\SpecialChar ~
-\SpecialChar ~
-\SpecialChar ~
-pop\SpecialChar ~
-\SpecialChar ~
-\SpecialChar ~
-\SpecialChar ~
-\SpecialChar ~
-acc
+about Functions using private register banks.
+\layout Subsection
+
+MCS51/DS390 Interrupt Service Routines
+\layout Standard
+
+Interrupt numbers and the corresponding address & descriptions for the Standard
+ 8051/8052 are listed below.
+ SDCC will automatically adjust the interrupt vector table to the maximum
+ interrupt number specified.
\newline
-\SpecialChar ~
-\SpecialChar ~
-\SpecialChar ~
-\SpecialChar ~
-reti
+
\layout Standard
+\align center
-whereas nakedInterrupt looks like:
-\layout Verse
+\begin_inset Tabular
+<lyxtabular version="3" rows="7" columns="3">
+<features>
+<column alignment="center" valignment="top" leftline="true" width="0in">
+<column alignment="center" valignment="top" leftline="true" width="0in">
+<column alignment="center" valignment="top" leftline="true" rightline="true" width="0in">
+<row topline="true" bottomline="true">
+<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
+\begin_inset Text
+\layout Standard
+
+Interrupt #
+\end_inset
+</cell>
+<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
+\begin_inset Text
-\family typewriter
-_nakedInterrupt:
-\newline
-\SpecialChar ~
-\SpecialChar ~
-\SpecialChar ~
-\SpecialChar ~
-inc\SpecialChar ~
-\SpecialChar ~
-\SpecialChar ~
-\SpecialChar ~
-_counter
-\newline
-\SpecialChar ~
-\SpecialChar ~
-\SpecialChar ~
-\SpecialChar ~
-reti\SpecialChar ~
-\SpecialChar ~
-\SpecialChar ~
-; MUST explicitly include ret or reti in _naked function.
\layout Standard
-The #pragma directive EXCLUDE
-\begin_inset LatexCommand \index{\#pragma EXCLUDE}
+Description
+\end_inset
+</cell>
+<cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
+\begin_inset Text
+
+\layout Standard
+Vector Address
\end_inset
+</cell>
+</row>
+<row topline="true">
+<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
+\begin_inset Text
- allows a more fine grained control over pushing & popping
-\begin_inset LatexCommand \index{push/pop}
+\layout Standard
+0
\end_inset
+</cell>
+<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
+\begin_inset Text
- the registers.
\layout Standard
-While there is nothing preventing you from writing C code inside a _naked
- function, there are many ways to shoot yourself in the foot doing this,
- and it is recommended that you stick to inline assembler.
-\layout Subsection
+External 0
+\end_inset
+</cell>
+<cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
+\begin_inset Text
-Use of Labels within Inline Assembler
\layout Standard
-SDCC allows the use of in-line assembler with a few restriction as regards
- labels.
- In older versions of the compiler all labels defined within inline assembler
- code
-\emph on
-had to be
-\emph default
- of the form
-\emph on
-nnnnn$
-\emph default
- where nnnn is a number less than 100 (which implies a limit of utmost 100
- inline assembler labels
-\emph on
-per function
-\emph default
-\noun on
-)
-\noun default
-.
-
-\layout Verse
+0x0003
+\end_inset
+</cell>
+</row>
+<row topline="true">
+<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
+\begin_inset Text
+\layout Standard
-\family typewriter
-_asm
-\begin_inset LatexCommand \index{\_asm}
+1
+\end_inset
+</cell>
+<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
+\begin_inset Text
+\layout Standard
+
+Timer 0
\end_inset
+</cell>
+<cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
+\begin_inset Text
-
-\newline
-\SpecialChar ~
-\SpecialChar ~
-\SpecialChar ~
-\SpecialChar ~
-mov\SpecialChar ~
-\SpecialChar ~
-\SpecialChar ~
-\SpecialChar ~
-\SpecialChar ~
-b,#10
-\newline
-00001$:
-\newline
-\SpecialChar ~
-\SpecialChar ~
-\SpecialChar ~
-\SpecialChar ~
-djnz\SpecialChar ~
-\SpecialChar ~
-\SpecialChar ~
-\SpecialChar ~
-b,00001$
-\newline
-_endasm
-\begin_inset LatexCommand \index{\_endasm}
+\layout Standard
+0x000B
\end_inset
+</cell>
+</row>
+<row topline="true">
+<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
+\begin_inset Text
- ;
\layout Standard
-Inline assembler code cannot reference any C-Labels, however it can reference
- labels
-\begin_inset LatexCommand \index{Labels}
-
+2
\end_inset
+</cell>
+<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
+\begin_inset Text
- defined by the inline assembler, e.g.:
-\layout Verse
+\layout Standard
+External 1
+\end_inset
+</cell>
+<cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
+\begin_inset Text
-\family typewriter
-foo() {
-\newline
-\SpecialChar ~
-\SpecialChar ~
-\SpecialChar ~
-\SpecialChar ~
-/* some c code */
-\newline
-\SpecialChar ~
-\SpecialChar ~
-\SpecialChar ~
-\SpecialChar ~
-_asm
-\newline
-\SpecialChar ~
-\SpecialChar ~
-\SpecialChar ~
-\SpecialChar ~
-\SpecialChar ~
-\SpecialChar ~
-; some assembler code
-\newline
-\SpecialChar ~
-\SpecialChar ~
-\SpecialChar ~
-\SpecialChar ~
-\SpecialChar ~
-\SpecialChar ~
-ljmp $0003
-\newline
-\SpecialChar ~
-\SpecialChar ~
-\SpecialChar ~
-\SpecialChar ~
-_endasm;
-\newline
-\SpecialChar ~
-\SpecialChar ~
-\SpecialChar ~
-\SpecialChar ~
-/* some more c code */
-\newline
-clabel:\SpecialChar ~
-\SpecialChar ~
-/* inline assembler cannot reference this label */
-\newline
-\SpecialChar ~
-\SpecialChar ~
-\SpecialChar ~
-\SpecialChar ~
-_asm
-\newline
-\SpecialChar ~
-\SpecialChar ~
-\SpecialChar ~
-\SpecialChar ~
-$0003: ;label (can be reference by inline assembler only)
-\newline
-\SpecialChar ~
-\SpecialChar ~
-\SpecialChar ~
-\SpecialChar ~
-_endasm ;
-\newline
-\SpecialChar ~
-\SpecialChar ~
-\SpecialChar ~
-\SpecialChar ~
-/* some more c code */
-\newline
-}
\layout Standard
-In other words inline assembly code can access labels defined in inline
- assembly within the scope of the function.
- The same goes the other way, ie.
- labels defines in inline assembly can not be accessed by C statements.
-\layout Section
+0x0013
+\end_inset
+</cell>
+</row>
+<row topline="true">
+<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
+\begin_inset Text
-Interfacing with Assembler Code
-\begin_inset LatexCommand \index{Assembler routines}
+\layout Standard
+3
\end_inset
+</cell>
+<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
+\begin_inset Text
+\layout Standard
-\layout Subsection
+Timer 1
+\end_inset
+</cell>
+<cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
+\begin_inset Text
-Global Registers used for Parameter Passing
-\begin_inset LatexCommand \index{Parameter passing}
+\layout Standard
+0x001B
\end_inset
-
+</cell>
+</row>
+<row topline="true">
+<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
+\begin_inset Text
\layout Standard
-The compiler always uses the global registers
-\emph on
-DPL, DPH
-\begin_inset LatexCommand \index{DPTR, DPH, DPL}
+4
+\end_inset
+</cell>
+<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
+\begin_inset Text
+
+\layout Standard
+Serial
\end_inset
+</cell>
+<cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
+\begin_inset Text
+\layout Standard
-\begin_inset LatexCommand \index{DPTR}
+0x0023
+\end_inset
+</cell>
+</row>
+<row topline="true" bottomline="true">
+<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
+\begin_inset Text
+
+\layout Standard
+5
\end_inset
+</cell>
+<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
+\begin_inset Text
-, B
-\begin_inset LatexCommand \index{B (register)}
+\layout Standard
+Timer 2 (8052)
\end_inset
+</cell>
+<cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
+\begin_inset Text
-
-\emph default
-and
-\emph on
- ACC
-\begin_inset LatexCommand \index{ACC}
+\layout Standard
+0x002B
\end_inset
+</cell>
+</row>
+</lyxtabular>
+\end_inset
-\emph default
- to pass the first parameter to a routine.
- The second parameter onwards is either allocated on the stack (for reentrant
- routines or if -
-\begin_inset ERT
-status Collapsed
+
+\newline
\layout Standard
-\backslash
-/
+If the interrupt service routine is defined without
+\emph on
+using
+\begin_inset LatexCommand \index{using (mcs51, ds390 register bank)}
+
\end_inset
--stack-auto is used) or in data / xdata memory (depending on the memory
- model).
-
-\layout Subsection
-Assembler Routine(non-reentrant
-\begin_inset LatexCommand \index{reentrant}
+\begin_inset LatexCommand \index{\_\_using (mcs51, ds390 register bank)}
\end_inset
-)
-\begin_inset LatexCommand \index{Assembler routines (non-reentrant)}
-\end_inset
+\emph default
+ a register bank or with register bank 0 (
+\emph on
+using
+\emph default
+ 0), the compiler will save the registers used by itself on the stack upon
+ entry and restore them at exit, however if such an interrupt service routine
+ calls another function then the entire register bank will be saved on the
+ stack.
+ This scheme may be advantageous for small interrupt service routines which
+ have low register usage.
+\layout Standard
+If the interrupt service routine is defined to be using a specific register
+ bank then only
+\emph on
+a, b, dptr
+\emph default
+ & psw are saved and restored, if such an interrupt service routine calls
+ another function (using another register bank) then the entire register
+ bank of the called function will be saved on the stack.
+ This scheme is recommended for larger interrupt service routines.
+\layout Subsection
+HC08 Interrupt Service Routines
\layout Standard
-In the following example the function c_func calls an assembler routine
- asm_func, which takes two parameters
-\begin_inset LatexCommand \index{function parameter}
+Since the number of interrupts available is chip specific and the interrupt
+ vector table always ends at the last byte of memory, the interrupt numbers
+ corresponds to the interrupt vectors in reverse order of address.
+ For example, interrupt 1 will use the interrupt vector at 0xfffc, interrupt
+ 2 will use the interrupt vector at 0xfffa, and so on.
+ However, interrupt 0 (the reset vector at 0xfffe) is not redefinable in
+ this way; instead see section
+\begin_inset LatexCommand \ref{sub:Startup-Code}
\end_inset
-.
+ for details on customizing startup.
+\layout Subsection
+
+Z80 Interrupt Service Routines
+\layout Standard
+
+The Z80 uses several different methods for determining the correct interrupt
+ vector depending on the hardware implementation.
+ Therefore, SDCC ignores the optional interrupt number and does not attempt
+ to generate an interrupt vector table.
+\layout Standard
+
+By default, SDCC generates code for a maskable interrupt, which uses an
+ RETI instruction to return from the interrupt.
+ To write an interrupt handler for the non-maskable interrupt, which needs
+ an RETN instruction instead, add the
+\emph on
+critical
+\emph default
+ keyword:
\layout Verse
\family typewriter
-extern int asm_func(unsigned char, unsigned char);
-\newline
-
-\newline
-int c_func (unsigned char i, unsigned char j)
+void nmi_isr (void) critical interrupt
\newline
-{
+{
\newline
\SpecialChar ~
\SpecialChar ~
\SpecialChar ~
\SpecialChar ~
-return asm_func(i,j);
+...
+
\newline
}
-\newline
+\layout Section
-\newline
-int main()
-\newline
-{
-\newline
-\SpecialChar ~
-\SpecialChar ~
-\SpecialChar ~
-\SpecialChar ~
-return c_func(10,9);
-\newline
-}
+Enabling and Disabling Interrupts
+\layout Subsection
+
+Critical Functions and Critical Statements
\layout Standard
-The corresponding assembler function is:
+A special keyword may be associated with a block or a function declaring
+ it as
+\emph on
+critical
+\emph default
+.
+ SDCC will generate code to disable all interrupts
+\begin_inset LatexCommand \index{interrupt}
+
+\end_inset
+
+ upon entry to a critical function and restore the interrupt enable to the
+ previous state before returning.
+ Nesting critical functions will need one additional byte on the stack
+\begin_inset LatexCommand \index{stack}
+
+\end_inset
+
+ for each call.
\layout Verse
\family typewriter
-.globl _asm_func_PARM_2
+int foo () critical
+\begin_inset LatexCommand \index{critical}
+
+\end_inset
+
+
+\begin_inset LatexCommand \index{\_\_critical}
+
+\end_inset
+
+
+\newline
+{
\newline
\SpecialChar ~
\SpecialChar ~
\SpecialChar ~
\SpecialChar ~
+...
+
+\newline
\SpecialChar ~
\SpecialChar ~
\SpecialChar ~
\SpecialChar ~
-.globl _asm_func
+...
+
+\newline
+}
+\layout Standard
+
+The critical attribute maybe used with other attributes like
+\emph on
+reentrant.
+\emph default
+
\newline
+The keyword
+\emph on
+critical
+\emph default
+ may also be used to disable interrupts more locally:
+\layout Verse
+
+
+\family typewriter
+critical{ i++; }
+\layout Standard
+
+More than one statement could have been included in the block.
+\layout Subsection
+
+Enabling and Disabling Interrupts directly
+\layout Standard
+
+Interrupts
+\begin_inset LatexCommand \index{interrupt}
+
+\end_inset
+
+ can also be disabled and enabled directly (8051):
+\layout Verse
+
+
+\family typewriter
+EA = 0;\SpecialChar ~
\SpecialChar ~
\SpecialChar ~
\SpecialChar ~
\SpecialChar ~
\SpecialChar ~
\SpecialChar ~
-.area OSEG
-\newline
-_asm_func_PARM_2:
-\newline
\SpecialChar ~
\SpecialChar ~
\SpecialChar ~
+or:\SpecialChar ~
\SpecialChar ~
\SpecialChar ~
\SpecialChar ~
\SpecialChar ~
\SpecialChar ~
-.ds 1
-\newline
\SpecialChar ~
\SpecialChar ~
\SpecialChar ~
\SpecialChar ~
\SpecialChar ~
+EA_SAVE = EA;
+\layout Verse
+
+
+\family typewriter
+...\SpecialChar ~
\SpecialChar ~
\SpecialChar ~
\SpecialChar ~
-.area CSEG
-\newline
-_asm_func:
-\newline
\SpecialChar ~
\SpecialChar ~
\SpecialChar ~
\SpecialChar ~
\SpecialChar ~
\SpecialChar ~
-mov a,dpl
-\newline
\SpecialChar ~
\SpecialChar ~
\SpecialChar ~
\SpecialChar ~
\SpecialChar ~
\SpecialChar ~
-add a,_asm_func_PARM_2
-\newline
\SpecialChar ~
\SpecialChar ~
\SpecialChar ~
\SpecialChar ~
\SpecialChar ~
\SpecialChar ~
-mov dpl,a
-\newline
\SpecialChar ~
\SpecialChar ~
+EA = 0;
+\layout Verse
+
+
+\family typewriter
+EA = 1;\SpecialChar ~
\SpecialChar ~
\SpecialChar ~
\SpecialChar ~
\SpecialChar ~
\SpecialChar ~
\SpecialChar ~
-mov\SpecialChar ~
\SpecialChar ~
\SpecialChar ~
\SpecialChar ~
-dph
-\begin_inset LatexCommand \index{DPTR, DPH, DPL}
-
-\end_inset
-
-,#0x00
-\newline
\SpecialChar ~
\SpecialChar ~
\SpecialChar ~
\SpecialChar ~
\SpecialChar ~
\SpecialChar ~
-ret
-\layout Standard
-
-Note here that the return values
-\begin_inset LatexCommand \index{return value}
-
-\end_inset
-
- are placed in 'dpl' - One byte return value, 'dpl' LSB & 'dph' MSB for
- two byte values.
- 'dpl', 'dph' and 'b' for three byte values (generic pointers) and 'dpl','dph','
-b' & 'acc' for four byte values.
-\layout Standard
-
-The parameter naming convention is _<function_name>_PARM_<n>, where n is
- the parameter number starting from 1, and counting from the left.
- The first parameter is passed in
-\begin_inset Quotes eld
-\end_inset
-
-dpl
-\begin_inset Quotes erd
-\end_inset
-
- for One bye parameter,
-\begin_inset Quotes eld
-\end_inset
-
-dptr
-\begin_inset Quotes erd
-\end_inset
-
- if two bytes,
-\begin_inset Quotes eld
-\end_inset
-
-b,dptr
-\begin_inset Quotes erd
-\end_inset
-
- for three bytes and
-\begin_inset Quotes eld
-\end_inset
-
-acc,b,dptr
-\begin_inset Quotes erd
-\end_inset
-
- for four bytes, the variable name for the second parameter will be _<function_n
-ame>_PARM_2.
-\newline
-
-\newline
-Assemble the assembler routine with the following command:
-\newline
-
-\newline
-
-\family sans
-\series bold
-asx8051 -losg asmfunc.asm
-\newline
-
-\newline
-
-\family default
-\series default
-Then compile and link the assembler routine to the C source file with the
- following command:
-\newline
-
-\newline
-
-\family sans
-\series bold
-sdcc cfunc.c asmfunc.rel
-\layout Subsection
-
-Assembler Routine(reentrant
-\begin_inset LatexCommand \index{reentrant}
-
-\end_inset
-
-)
-\begin_inset LatexCommand \index{Assembler routines (reentrant)}
-
-\end_inset
-
-
-\layout Standard
-
-In this case the second parameter
-\begin_inset LatexCommand \index{function parameter}
-
-\end_inset
-
- onwards will be passed on the stack, the parameters are pushed from right
- to left i.e.
- after the call the left most parameter will be on the top of the stack.
- Here is an example:
-\layout Verse
-
-
-\family typewriter
-extern int asm_func(unsigned char, unsigned char);
-\newline
-
-\newline
-int c_func (unsigned char i, unsigned char j) reentrant
-\newline
-{
-\newline
\SpecialChar ~
\SpecialChar ~
\SpecialChar ~
\SpecialChar ~
-return asm_func(i,j);
-\newline
-}
-\newline
-
-\newline
-int main()
-\newline
-{
-\newline
\SpecialChar ~
\SpecialChar ~
\SpecialChar ~
\SpecialChar ~
-return c_func(10,9);
-\newline
-}
-\layout Standard
-
-The corresponding assembler routine is:
+...
\layout Verse
\family typewriter
-.globl _asm_func
-\newline
-_asm_func:
-\newline
\SpecialChar ~
\SpecialChar ~
\SpecialChar ~
\SpecialChar ~
-push _bp
-\newline
\SpecialChar ~
\SpecialChar ~
\SpecialChar ~
\SpecialChar ~
-mov _bp,sp
-\newline
\SpecialChar ~
\SpecialChar ~
\SpecialChar ~
\SpecialChar ~
-mov r2,dpl
-\newline
\SpecialChar ~
\SpecialChar ~
\SpecialChar ~
\SpecialChar ~
-mov a,_bp
-\newline
\SpecialChar ~
\SpecialChar ~
\SpecialChar ~
\SpecialChar ~
-clr c
-\newline
\SpecialChar ~
\SpecialChar ~
\SpecialChar ~
\SpecialChar ~
-add a,#0xfd
-\newline
\SpecialChar ~
\SpecialChar ~
\SpecialChar ~
\SpecialChar ~
-mov r0,a
-\newline
\SpecialChar ~
\SpecialChar ~
\SpecialChar ~
\SpecialChar ~
-add a,#0xfc
-\newline
\SpecialChar ~
-\SpecialChar ~
-\SpecialChar ~
-\SpecialChar ~
-mov r1,a
-\newline
-\SpecialChar ~
-\SpecialChar ~
-\SpecialChar ~
-\SpecialChar ~
-mov a,@r0
-\newline
-\SpecialChar ~
-\SpecialChar ~
-\SpecialChar ~
-\SpecialChar ~
-add a,r2
-\newline
-\SpecialChar ~
-\SpecialChar ~
-\SpecialChar ~
-\SpecialChar ~
-mov dpl,a
-\newline
-\SpecialChar ~
-\SpecialChar ~
-\SpecialChar ~
-\SpecialChar ~
-mov dph,#0x00
-\newline
-\SpecialChar ~
-\SpecialChar ~
-\SpecialChar ~
-\SpecialChar ~
-mov sp,_bp
-\newline
-\SpecialChar ~
-\SpecialChar ~
-\SpecialChar ~
-\SpecialChar ~
-pop _bp
-\newline
-\SpecialChar ~
-\SpecialChar ~
-\SpecialChar ~
-\SpecialChar ~
-ret
+EA = EA_SAVE;
\layout Standard
-The compiling and linking procedure remains the same, however note the extra
- entry & exit linkage required for the assembler code, _bp is the stack
- frame pointer and is used to compute the offset into the stack for parameters
- and local variables.
-\layout Section
-
-int (16 bit)
-\begin_inset LatexCommand \index{int (16 bit)}
+On other architectures which have seperate opcodes for enabling and disabling
+ interrupts you might want to make use of defines with inline assembly
+\begin_inset LatexCommand \index{Assembler routines}
\end_inset
- and long (32 bit)
-\begin_inset LatexCommand \index{long (32 bit)}
+ (HC08):
+\layout Verse
-\end_inset
- Support
-\layout Standard
+\family typewriter
+#define CLI _asm
+\begin_inset LatexCommand \index{\_asm}
-For signed & unsigned int (16 bit) and long (32 bit) variables, division,
- multiplication and modulus operations are implemented by support routines.
- These support routines are all developed in ANSI-C to facilitate porting
- to other MCUs, although some model specific assembler optimizations are
- used.
- The following files contain the described routines, all of them can be
- found in <installdir>/share/sdcc/lib.
-\newline
+\end_inset
-\layout Standard
-\align center
+\SpecialChar ~
+\SpecialChar ~
+cli\SpecialChar ~
+\SpecialChar ~
+_endasm
+\begin_inset LatexCommand \index{\_endasm}
-\begin_inset Tabular
-<lyxtabular version="3" rows="11" columns="2">
-<features>
-<column alignment="center" valignment="top" leftline="true" width="0">
-<column alignment="center" valignment="top" leftline="true" rightline="true" width="0">
-<row topline="true" bottomline="true">
-<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
-\begin_inset Text
+\end_inset
-\layout Standard
+;
+\layout Verse
-\series bold
-Function
-\end_inset
-</cell>
-<cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
-\begin_inset Text
+\family typewriter
+#define SEI _asm\SpecialChar ~
+\SpecialChar ~
+sei\SpecialChar ~
+\SpecialChar ~
+_endasm;
+\layout Verse
+
+\family typewriter
+...
\layout Standard
+Note: it is sometimes sufficient to disable only a specific interrupt source
+ like f.e.
+ a timer or serial interrupt by manipulating an
+\emph on
+interrupt mask
+\begin_inset LatexCommand \index{interrupt mask}
-\series bold
-Description
\end_inset
-</cell>
-</row>
-<row topline="true">
-<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
-\begin_inset Text
-\layout Standard
-
-_mulint.c
-\end_inset
-</cell>
-<cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
-\begin_inset Text
+\emph default
+ register.
+
\layout Standard
-16 bit multiplication
-\end_inset
-</cell>
-</row>
-<row topline="true">
-<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
-\begin_inset Text
+Usually the time during which interrupts are disabled should be kept as
+ short as possible.
+ This minimizes both
+\emph on
+interrupt latency
+\emph default
-\layout Standard
+\begin_inset LatexCommand \index{interrupt latency}
-_divsint.c
\end_inset
-</cell>
-<cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
-\begin_inset Text
-\layout Standard
+ (the time between the occurrence of the interrupt and the execution of
+ the first code in the interrupt routine) and
+\emph on
+interrupt jitter
+\emph default
+
+\begin_inset LatexCommand \index{interrupt jitter}
- signed 16 bit division (calls _divuint)
\end_inset
-</cell>
-</row>
-<row topline="true">
-<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
-\begin_inset Text
+ (the difference between the shortest and the longest interrupt latency).
+ These really are something different, f.e.
+ a serial interrupt has to be served before its buffer overruns so it cares
+ for the maximum interrupt latency, whereas it does not care about jitter.
+ On a loudspeaker driven via a digital to analog converter which is fed
+ by an interrupt a latency of a few milliseconds might be tolerable, whereas
+ a much smaller jitter will be very audible.
\layout Standard
-_divuint.c
-\end_inset
-</cell>
-<cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
-\begin_inset Text
+You can reenable interrupts within an interrupt routine and on some architecture
+s you can make use of two (or more) levels of
+\emph on
+interrupt priorities
+\emph default
-\layout Standard
+\begin_inset LatexCommand \index{interrupt priority}
- unsigned 16 bit division
\end_inset
-</cell>
-</row>
-<row topline="true">
-<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
-\begin_inset Text
-\layout Standard
+.
+ On some architectures which don't support interrupt priorities these can
+ be implemented by manipulating the interrupt mask and reenabling interrupts
+ within the interrupt routine.
+ Check there is sufficient space on the stack
+\begin_inset LatexCommand \index{stack}
-_modsint.c
\end_inset
-</cell>
-<cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
-\begin_inset Text
-\layout Standard
+ and don't add complexity unless you have to.
+
+\layout Subsection
+
+Semaphore
+\begin_inset LatexCommand \index{semaphore}
-signed 16 bit modulus (calls _moduint)
\end_inset
-</cell>
-</row>
-<row topline="true">
-<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
-\begin_inset Text
+ locking (mcs51/ds390)
\layout Standard
-_moduint.c
+Some architectures (mcs51/ds390) have an atomic
+\begin_inset LatexCommand \index{atomic}
+
\end_inset
-</cell>
-<cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
-\begin_inset Text
-\layout Standard
+ bit test and
+\emph on
+
+\emph default
+clear
+\emph on
+
+\emph default
+instruction.
+ These type of instructions are typically used in preemptive multitasking
+ systems, where a routine f.e.
+ claims the use of a data structure ('acquires a lock
+\begin_inset LatexCommand \index{lock}
-unsigned 16 bit modulus
\end_inset
-</cell>
-</row>
-<row topline="true">
-<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
-\begin_inset Text
-\layout Standard
+ on it'), makes some modifications and then releases the lock when the data
+ structure is consistent again.
+ The instruction may also be used if interrupt and non-interrupt code have
+ to compete for a resource.
+ With the atomic bit test and clear instruction interrupts
+\begin_inset LatexCommand \index{interrupt}
-_mullong.c
\end_inset
-</cell>
-<cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
-\begin_inset Text
+ don't have to be disabled for the locking operation.
+
\layout Standard
-32 bit multiplication
-\end_inset
-</cell>
-</row>
-<row topline="true">
-<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
-\begin_inset Text
+SDCC generates this instruction if the source follows this pattern:
+\layout Verse
-\layout Standard
-_divslong.c
+\family typewriter
+volatile
+\begin_inset LatexCommand \index{volatile}
+
\end_inset
-</cell>
-<cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
-\begin_inset Text
-\layout Standard
-
- signed 32 division (calls _divulong)
-\end_inset
-</cell>
-</row>
-<row topline="true">
-<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
-\begin_inset Text
+ bit resource_is_free;
+\newline
+\newline
+if (resource_is_free)
+\newline
+\SpecialChar ~
+\SpecialChar ~
+{
+\newline
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+resource_is_free=0;
+\newline
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+...
+
+\newline
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+resource_is_free=1;
+\newline
+\SpecialChar ~
+\SpecialChar ~
+}
\layout Standard
-_divulong.c
+Note, mcs51 and ds390 support only an atomic
+\begin_inset LatexCommand \index{atomic}
+
\end_inset
-</cell>
-<cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
-\begin_inset Text
-\layout Standard
+ bit test and
+\emph on
+clear
+\emph default
+ instruction (as opposed to atomic bit test and
+\emph on
+set).
+\layout Section
+
+Functions using private register banks
+\begin_inset LatexCommand \label{sub:Functions-using-private-banks}
-unsigned 32 division
\end_inset
-</cell>
-</row>
-<row topline="true">
-<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
-\begin_inset Text
+ (mcs51/ds390)
\layout Standard
-_modslong.c
+Some architectures have support for quickly changing register sets.
+ SDCC supports this feature with the
+\emph on
+using
+\begin_inset LatexCommand \index{using (mcs51, ds390 register bank)}
+
\end_inset
-</cell>
-<cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
-\begin_inset Text
+
+\begin_inset LatexCommand \index{\_\_using (mcs51, ds390 register bank)}
+
+\end_inset
+
+
+\emph default
+ attribute (which tells the compiler to use a register bank
+\begin_inset LatexCommand \index{register bank (mcs51, ds390)}
+
+\end_inset
+
+ other than the default bank zero).
+ It should only be applied to
+\emph on
+interrupt
+\begin_inset LatexCommand \index{interrupt}
+
+\end_inset
+
+
+\emph default
+ functions (see footnote below).
+ This will in most circumstances make the generated ISR code more efficient
+ since it will not have to save registers on the stack.
\layout Standard
- signed 32 bit modulus (calls _modulong)
+The
+\emph on
+using
+\emph default
+ attribute will have no effect on the generated code for a
+\emph on
+non-interrupt
+\emph default
+ function (but may occasionally be useful anyway
+\begin_inset Foot
+collapsed false
+
+\layout Standard
+
+possible exception: if a function is called ONLY from 'interrupt' functions
+ using a particular bank, it can be declared with the same 'using' attribute
+ as the calling 'interrupt' functions.
+ For instance, if you have several ISRs using bank one, and all of them
+ call memcpy(), it might make sense to create a specialized version of memcpy()
+ 'using 1', since this would prevent the ISR from having to save bank zero
+ to the stack on entry and switch to bank zero before calling the function
\end_inset
-</cell>
-</row>
-<row topline="true" bottomline="true">
-<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
-\begin_inset Text
+).
+\newline
+
+\emph on
+(pending: I don't think this has been done yet)
\layout Standard
-_modulong.c
+An
+\emph on
+interrupt
+\emph default
+ function using a non-zero bank will assume that it can trash that register
+ bank, and will not save it.
+ Since high-priority interrupts
+\begin_inset LatexCommand \index{interrupts}
+
\end_inset
-</cell>
-<cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
-\begin_inset Text
+
+\begin_inset LatexCommand \index{interrupt priority}
+
+\end_inset
+
+ can interrupt low-priority ones on the 8051 and friends, this means that
+ if a high-priority ISR
+\emph on
+using
+\emph default
+ a particular bank occurs while processing a low-priority ISR
+\emph on
+using
+\emph default
+ the same bank, terrible and bad things can happen.
+ To prevent this, no single register bank should be
+\emph on
+used
+\emph default
+ by both a high priority and a low priority ISR.
+ This is probably most easily done by having all high priority ISRs use
+ one bank and all low priority ISRs use another.
+ If you have an ISR which can change priority at runtime, you're on your
+ own: I suggest using the default bank zero and taking the small performance
+ hit.
\layout Standard
-unsigned 32 bit modulus
+It is most efficient if your ISR calls no other functions.
+ If your ISR must call other functions, it is most efficient if those functions
+ use the same bank as the ISR (see note 1 below); the next best is if the
+ called functions use bank zero.
+ It is very inefficient to call a function using a different, non-zero bank
+ from an ISR.
+
+\layout Section
+
+Startup Code
+\begin_inset LatexCommand \label{sub:Startup-Code}
+
\end_inset
-</cell>
-</row>
-</lyxtabular>
+
+
+\begin_inset LatexCommand \index{Startup code}
\end_inset
-\newline
+\layout Subsection
+MCS51/DS390 Startup Code
\layout Standard
-Since they are compiled as
+The compiler inserts a call to the C routine
\emph on
-non-reentrant
+_sdcc_external_startup()
+\begin_inset LatexCommand \index{\_sdcc\_external\_startup()}
+
+\end_inset
+
+
+\series bold
\emph default
+
+\series default
+at the start of the CODE area.
+ This routine is in the runtime library
+\begin_inset LatexCommand \index{Runtime library}
-\begin_inset LatexCommand \index{reentrant}
+\end_inset
+
+.
+ By default this routine returns 0, if this routine returns a non-zero value,
+ the static & global variable initialization will be skipped and the function
+ main will be invoked.
+ Otherwise static & global variables will be initialized before the function
+ main is invoked.
+ You could add a
+\emph on
+_sdcc_external_startup()
+\emph default
+ routine to your program to override the default if you need to setup hardware
+ or perform some other critical operation prior to static & global variable
+ initialization
+\begin_inset LatexCommand \index{Variable initialization}
\end_inset
-, interrupt
-\begin_inset LatexCommand \index{interrupt}
+.
+ On some mcs51 variants xdata
+\begin_inset LatexCommand \index{xdata (mcs51, ds390 storage class)}
\end_inset
- service routines should not do any of the above operations.
- If this is unavoidable then the above routines will need to be compiled
- with the
+ memory has to be explicitly enabled before it can be accessed or if the
+ watchdog needs to be disabled, this is the place to do it.
+ The startup code clears all internal data memory, 256 bytes by default,
+ but from 0 to n-1 if
\emph on
-
\begin_inset ERT
/
\end_inset
--stack-auto
-\begin_inset LatexCommand \index{-\/-stack-auto}
+-iram-size
+\begin_inset LatexCommand \index{-\/-iram-size <Value>}
\end_inset
-
+n
\emph default
- option, after which the source program will have to be compiled with
+ is used.
+ (recommended for Chipcon CC1010).
+\layout Standard
+
+See also the compiler option
\emph on
-
\begin_inset ERT
/
\end_inset
--int-long-reent
-\begin_inset LatexCommand \index{-\/-int-long-reent}
-
-\end_inset
-
-
+-no-xinit
+\emph default
+-
+\emph on
+opt
\emph default
- option.
- Notice that you don't have to call this routines directly.
- The compiler will use them automatically every time an integer operation
- is required.
-\layout Section
-Floating Point Support
-\begin_inset LatexCommand \index{Floating point support}
+\begin_inset LatexCommand \index{-\/-no-xinit-opt}
\end_inset
+ and section
+\begin_inset LatexCommand \ref{sub:MCS51-variants}
-\layout Standard
+\end_inset
-SDCC supports IEEE (single precision 4 bytes) floating point numbers.The
- floating point support routines are derived from gcc's floatlib.c and consist
- of the following routines:
-\newline
+\SpecialChar ~
+about MCS51-variants.
+\layout Subsection
+HC08 Startup Code
\layout Standard
-\align center
-
-\size footnotesize
-\begin_inset Tabular
-<lyxtabular version="3" rows="17" columns="2">
-<features>
-<column alignment="center" valignment="top" leftline="true" width="0">
-<column alignment="center" valignment="top" leftline="true" rightline="true" width="0">
-<row topline="true" bottomline="true">
-<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
-\begin_inset Text
+The HC08 startup code follows the same scheme as the MCS51 startup code.
+\layout Subsection
+Z80 Startup Code
\layout Standard
-
-\family roman
-\series medium
-\shape up
-\size normal
-\emph off
-\bar no
-\noun off
-\color none
-Function
-\end_inset
-</cell>
-<cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
-\begin_inset Text
+On the Z80 the startup code is inserted by linking with crt0.o which is generated
+ from sdcc/device/lib/z80/crt0.s.
+ If you need a different startup code you can use the compiler option
+\emph on
+-
+\series bold
+\emph default
+
+\begin_inset ERT
+status Collapsed
\layout Standard
-Description
+\backslash
+/
\end_inset
-</cell>
-</row>
-<row topline="true">
-<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
-\begin_inset Text
-\layout Standard
+\series default
+\emph on
+-no-std-crt0
+\emph default
+
+\begin_inset LatexCommand \index{-\/-no-std-crt0}
-\family roman
-\series medium
-\shape up
-\size normal
-\emph off
-\bar no
-\noun off
-\color none
-_fsadd.c
\end_inset
-</cell>
-<cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
-\begin_inset Text
-\layout Standard
+ and provide your own crt0.o.
+
+\layout Section
+Inline Assembler Code
+\begin_inset LatexCommand \index{Assembler routines}
-\family roman
-\series medium
-\shape up
-\size normal
-\emph off
-\bar no
-\noun off
-\color none
-add floating point numbers
\end_inset
-</cell>
-</row>
-<row topline="true">
-<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
-\begin_inset Text
-\layout Standard
+\layout Subsection
+
+A Step by Step Introduction
+\begin_inset LatexCommand \label{sub:A-Step-by Assembler Introduction}
-\family roman
-\series medium
-\shape up
-\size normal
-\emph off
-\bar no
-\noun off
-\color none
-_fssub.c
\end_inset
-</cell>
-<cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
-\begin_inset Text
-\layout Standard
+\layout Standard
-\family roman
-\series medium
-\shape up
-\size normal
-\emph off
-\bar no
-\noun off
-\color none
-subtract floating point numbers
-\end_inset
-</cell>
-</row>
-<row topline="true">
-<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
-\begin_inset Text
+Starting from a small snippet of c-code this example shows for the MCS51
+ how to use inline assembly, access variables, a function parameter and
+ an array in xdata memory.
+ The example uses an MCS51 here but is easily adapted for other architectures.
+ This is a buffer routine which should be optimized:
+\layout Verse
-\layout Standard
+\family typewriter
+\size footnotesize
+unsigned char far
+\begin_inset LatexCommand \index{far (storage class)}
-\family roman
-\series medium
-\shape up
-\size normal
-\emph off
-\bar no
-\noun off
-\color none
-_fsdiv.c
\end_inset
-</cell>
-<cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
-\begin_inset Text
-\layout Standard
+\begin_inset LatexCommand \index{\_\_far (storage class)}
-\family roman
-\series medium
-\shape up
-\size normal
-\emph off
-\bar no
-\noun off
-\color none
-divide floating point numbers
\end_inset
-</cell>
-</row>
-<row topline="true">
-<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
-\begin_inset Text
-
-\layout Standard
+ at
+\begin_inset LatexCommand \index{at}
-\family roman
-\series medium
-\shape up
-\size normal
-\emph off
-\bar no
-\noun off
-\color none
-_fsmul.c
\end_inset
-</cell>
-<cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
-\begin_inset Text
-\layout Standard
+\begin_inset LatexCommand \index{\_\_at}
-\family roman
-\series medium
-\shape up
-\size normal
-\emph off
-\bar no
-\noun off
-\color none
-multiply floating point numbers
\end_inset
-</cell>
-</row>
-<row topline="true">
-<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
-\begin_inset Text
-
-\layout Standard
+ 0x7f00 buf[0x100];
+\begin_inset LatexCommand \index{Aligned array}
-\family roman
-\series medium
-\shape up
-\size normal
-\emph off
-\bar no
-\noun off
-\color none
-_fs2uchar.c
\end_inset
-</cell>
-<cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
-\begin_inset Text
-
-\layout Standard
-\family roman
-\series medium
-\shape up
-\size normal
-\emph off
-\bar no
-\noun off
-\color none
-convert floating point to unsigned char
-\end_inset
-</cell>
-</row>
-<row topline="true">
-<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
-\begin_inset Text
+\newline
+unsigned char head,tail;
+\newline
+\newline
+void to_buffer( unsigned char c )
+\newline
+{
+\newline
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+if( head != tail-1 )
+\newline
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+buf[ head++ ] = c;\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+/* access to a 256 byte aligned array */
+\newline
+}
\layout Standard
-
-\family roman
-\series medium
-\shape up
-\size normal
-\emph off
-\bar no
-\noun off
-\color none
-_fs2char.c
+If the code snippet (assume it is saved in buffer.c) is compiled with SDCC
+ then a corresponding buffer.asm file is generated.
+ We define a new function
+\family typewriter
+to_buffer_asm()
+\family default
+ in file buffer.c in which we cut and paste the generated code, removing
+ unwanted comments and some ':'.
+ Then add
+\begin_inset Quotes sld
\end_inset
-</cell>
-<cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
-\begin_inset Text
-\layout Standard
+_asm
+\begin_inset Quotes srd
+\end_inset
+ and
+\begin_inset Quotes sld
+\end_inset
-\family roman
-\series medium
-\shape up
-\size normal
-\emph off
-\bar no
-\noun off
-\color none
-convert floating point to signed char
+_endasm;
+\begin_inset Quotes srd
\end_inset
-</cell>
-</row>
-<row topline="true">
-<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
-\begin_inset Text
-\layout Standard
-
-
-\family roman
-\series medium
-\shape up
-\size normal
-\emph off
-\bar no
-\noun off
-\color none
-_fs2uint.c
-\end_inset
-</cell>
-<cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
-\begin_inset Text
+ to the beginning and the end of the function body:
+\layout Verse
-\layout Standard
+\family typewriter
+\size footnotesize
+/* With a cut and paste from the .asm file, we have something to start with.
+\newline
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+The function is not yet OK! (registers aren't saved) */
+\newline
+void to_buffer_asm( unsigned char c )
+\newline
+{
+\newline
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+_asm
+\begin_inset LatexCommand \index{\_asm}
-\family roman
-\series medium
-\shape up
-\size normal
-\emph off
-\bar no
-\noun off
-\color none
-convert floating point to unsigned int
\end_inset
-</cell>
-</row>
-<row topline="true">
-<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
-\begin_inset Text
-\layout Standard
+\begin_inset LatexCommand \index{\_\_asm}
-\family roman
-\series medium
-\shape up
-\size normal
-\emph off
-\bar no
-\noun off
-\color none
-_fs2int.c
\end_inset
-</cell>
-<cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
-\begin_inset Text
-\layout Standard
+\newline
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+mov\SpecialChar ~
+\SpecialChar ~
+r2,dpl
+\newline
+;buffer.c if( head != tail-1 )
+\newline
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+mov\SpecialChar ~
+\SpecialChar ~
+a,_tail
+\newline
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+dec\SpecialChar ~
+\SpecialChar ~
+a
+\newline
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+mov\SpecialChar ~
+\SpecialChar ~
+r3,a
+\newline
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+mov\SpecialChar ~
+\SpecialChar ~
+a,_head
+\newline
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+cjne a,ar3,00106$
+\newline
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+ret
+\newline
+00106$:
+\newline
+;buffer.c buf[ head++ ] = c; /* access to a 256 byte aligned array */
+\begin_inset LatexCommand \index{Aligned array}
-\family roman
-\series medium
-\shape up
-\size normal
-\emph off
-\bar no
-\noun off
-\color none
-convert floating point to signed int
\end_inset
-</cell>
-</row>
-<row topline="true">
-<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
-\begin_inset Text
-\layout Standard
+\newline
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+mov\SpecialChar ~
+\SpecialChar ~
+r3,_head
+\newline
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+inc\SpecialChar ~
+\SpecialChar ~
+_head
+\newline
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+mov\SpecialChar ~
+\SpecialChar ~
+dpl,r3
+\newline
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+mov\SpecialChar ~
+\SpecialChar ~
+dph,#(_buf >> 8)
+\newline
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+mov\SpecialChar ~
+\SpecialChar ~
+a,r2
+\newline
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+movx @dptr,a
+\newline
+00103$:
+\newline
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+ret
+\newline
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+_endasm
+\begin_inset LatexCommand \index{\_endasm}
-\family roman
-\series medium
-\shape up
-\size normal
-\emph off
-\bar no
-\noun off
-\color none
-_fs2ulong.
-\family default
-\series default
-\shape default
-\size default
-\emph default
-\bar default
-\noun default
-\color default
-c
\end_inset
-</cell>
-<cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
-\begin_inset Text
-\layout Standard
+\begin_inset LatexCommand \index{\_\_endasm}
-\family roman
-\series medium
-\shape up
-\size normal
-\emph off
-\bar no
-\noun off
-\color none
-convert floating point to unsigned long
\end_inset
-</cell>
-</row>
-<row topline="true">
-<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
-\begin_inset Text
+;
+\newline
+}
\layout Standard
+The new file buffer.c should compile with only one warning about the unreferenced
+ function argument 'c'.
+ Now we hand-optimize the assembly code and insert an #define USE_ASSEMBLY
+ (1) and finally have:
+\layout Verse
-\family roman
-\series medium
-\shape up
-\size normal
-\emph off
-\bar no
-\noun off
-\color none
-_fs2long.c
-\end_inset
-</cell>
-<cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
-\begin_inset Text
-
-\layout Standard
-
-
-\family roman
-\series medium
-\shape up
-\size normal
-\emph off
-\bar no
-\noun off
-\color none
-convert floating point to signed long
-\end_inset
-</cell>
-</row>
-<row topline="true">
-<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
-\begin_inset Text
-
-\layout Standard
-
-
-\family roman
-\series medium
-\shape up
-\size normal
-\emph off
-\bar no
-\noun off
-\color none
-_uchar2fs.c
-\end_inset
-</cell>
-<cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
-\begin_inset Text
-
-\layout Standard
-
-
-\family roman
-\series medium
-\shape up
-\size normal
-\emph off
-\bar no
-\noun off
-\color none
-convert unsigned char to floating point
-\end_inset
-</cell>
-</row>
-<row topline="true">
-<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
-\begin_inset Text
-
-\layout Standard
-
-
-\family roman
-\series medium
-\shape up
-\size normal
-\emph off
-\bar no
-\noun off
-\color none
-_char2fs.c
-\end_inset
-</cell>
-<cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
-\begin_inset Text
-
-\layout Standard
-
-
-\family roman
-\series medium
-\shape up
-\size normal
-\emph off
-\bar no
-\noun off
-\color none
-convert char to floating point number
-\end_inset
-</cell>
-</row>
-<row topline="true">
-<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
-\begin_inset Text
-
-\layout Standard
-
-
-\family roman
-\series medium
-\shape up
-\size normal
-\emph off
-\bar no
-\noun off
-\color none
-_uint2fs.c
-\end_inset
-</cell>
-<cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
-\begin_inset Text
-
-\layout Standard
-
-
-\family roman
-\series medium
-\shape up
-\size normal
-\emph off
-\bar no
-\noun off
-\color none
-convert unsigned int to floating point
-\end_inset
-</cell>
-</row>
-<row topline="true">
-<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
-\begin_inset Text
-
-\layout Standard
-
-
-\family roman
-\series medium
-\shape up
-\size normal
-\emph off
-\bar no
-\noun off
-\color none
-_int2fs.c
-\end_inset
-</cell>
-<cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
-\begin_inset Text
-\layout Standard
+\family typewriter
+\size footnotesize
+unsigned char far at 0x7f00 buf[0x100];
+\newline
+unsigned char head,tail;
+\newline
+#define USE_ASSEMBLY (1)
+\newline
+\newline
+#if !USE_ASSEMBLY
+\newline
-\family roman
-\series medium
-\shape up
-\size normal
-\emph off
-\bar no
-\noun off
-\color none
-convert int to floating point numbers
-\end_inset
-</cell>
-</row>
-<row topline="true">
-<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
-\begin_inset Text
+\newline
+void to_buffer( unsigned char c )
+\newline
+{
+\newline
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+if( head != tail-1 )
+\newline
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+buf[ head++ ] = c;
+\newline
+}
+\newline
-\layout Standard
+\newline
+#else
+\newline
+\newline
+void to_buffer( unsigned char c )
+\newline
+{
+\newline
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+c; // to avoid warning: unreferenced function argument
+\newline
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+_asm
+\begin_inset LatexCommand \index{\_asm}
-\family roman
-\series medium
-\shape up
-\size normal
-\emph off
-\bar no
-\noun off
-\color none
-_ulong2fs.c
\end_inset
-</cell>
-<cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
-\begin_inset Text
-\layout Standard
+\begin_inset LatexCommand \index{\_\_asm}
-\family roman
-\series medium
-\shape up
-\size normal
-\emph off
-\bar no
-\noun off
-\color none
-convert unsigned long to floating point number
\end_inset
-</cell>
-</row>
-<row topline="true" bottomline="true">
-<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
-\begin_inset Text
-
-\layout Standard
-\family roman
-\series medium
-\shape up
-\size normal
-\emph off
-\bar no
-\noun off
-\color none
-_long2fs.c
-\end_inset
-</cell>
-<cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
-\begin_inset Text
+\newline
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+; save used registers here.
+
+\newline
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+; If we were still using r2,r3 we would have to push them here.
+
+\newline
+; if( head != tail-1 )
+\newline
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+mov\SpecialChar ~
+ a,_tail
+\newline
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+dec\SpecialChar ~
+ a
+\newline
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+xrl\SpecialChar ~
+ a,_head
+\newline
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+; we could do an ANL a,#0x0f here to use a smaller buffer (see below)
+\newline
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+jz\SpecialChar ~
+\SpecialChar ~
+ t_b_end$
+\newline
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+;
+\newline
+; buf[ head++ ] = c;
+\newline
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+mov\SpecialChar ~
+ a,dpl \SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+; dpl holds lower byte of function argument
+\newline
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+mov\SpecialChar ~
+ dpl,_head \SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+; buf is 0x100 byte aligned so head can be used directly
+\newline
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+mov\SpecialChar ~
+ dph,#(_buf>>8)
+\newline
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+movx @dptr,a
+\newline
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+inc \SpecialChar ~
+_head
+\newline
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+; we could do an ANL _head,#0x0f here to use a smaller buffer (see above)
+\newline
+t_b_end$:
+\newline
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+; restore used registers here
+\newline
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+_endasm
+\begin_inset LatexCommand \index{\_endasm}
-\layout Standard
+\end_inset
-\family roman
-\series medium
-\shape up
-\size normal
-\emph off
-\bar no
-\noun off
-\color none
-convert long to floating point number
-\end_inset
-</cell>
-</row>
-</lyxtabular>
+\begin_inset LatexCommand \index{\_\_endasm}
\end_inset
-
+;
\newline
-
+}
+\newline
+#endif
\layout Standard
-Note if all these routines are used simultaneously the data space might
- overflow.
- For serious floating point usage it is strongly recommended that the large
- model be used.
- Also notice that you don't have to call this routines directly.
- The compiler will use them automatically every time a floating point operation
- is required.
-\layout Section
+The inline assembler code can contain any valid code understood by the assembler
+, this includes any assembler directives and comment lines
+\begin_inset Foot
+collapsed false
-MCS51 Memory Models
-\begin_inset LatexCommand \index{Memory model}
+\layout Standard
+
+The assembler does not like some characters like ':' or ''' in comments.
+ You'll find an 100+ pages assembler manual in sdcc/as/doc/asxhtm.html
+\begin_inset LatexCommand \index{asXXXX (as-gbz80, as-hc08, asx8051, as-z80)}
\end_inset
-\begin_inset LatexCommand \index{MCS51 memory}
+\begin_inset LatexCommand \index{Assembler documentation}
\end_inset
-\layout Standard
+\end_inset
-SDCC allows two memory models for MCS51 code,
-\shape slanted
-small
-\shape default
- and
-\shape slanted
-large
-\shape default
.
- Modules compiled with different memory models should
-\emph on
-never
-\emph default
- be combined together or the results would be unpredictable.
- The library routines supplied with the compiler are compiled as both small
- and large.
- The compiled library modules are contained in separate directories as small
- and large so that you can link to either set.
-
-\layout Standard
-
-When the large model is used all variables declared without a storage class
- will be allocated into the external ram, this includes all parameters and
- local variables (for non-reentrant
-\begin_inset LatexCommand \index{reentrant}
+ The compiler does not do any validation of the code within the
+\family typewriter
+_asm
+\begin_inset LatexCommand \index{\_asm}
\end_inset
- functions).
- When the small model is used variables without storage class are allocated
- in the internal ram.
-\layout Standard
-Judicious usage of the processor specific storage classes
-\begin_inset LatexCommand \index{Storage class}
-
-\end_inset
-
- and the 'reentrant' function type will yield much more efficient code,
- than using the large model.
- Several optimizations are disabled when the program is compiled using the
- large model, it is therefore strongly recommended that the small model
- be used unless absolutely required.
-\layout Section
-
-DS390 Memory Models
-\begin_inset LatexCommand \index{Memory model}
-
-\end_inset
-
-
-\begin_inset LatexCommand \index{DS390 memory model}
+\begin_inset LatexCommand \index{\_\_asm}
\end_inset
+ ...
+ _endasm
+\size footnotesize
-\layout Standard
-
-The only model supported is Flat 24
-\begin_inset LatexCommand \index{Flat 24 (memory model)}
+\begin_inset LatexCommand \index{\_endasm}
\end_inset
-.
- This generates code for the 24 bit contiguous addressing mode of the Dallas
- DS80C390 part.
- In this mode, up to four meg of external RAM or code space can be directly
- addressed.
- See the data sheets at www.dalsemi.com for further information on this part.
-\newline
-
-\newline
-Note that the compiler does not generate any code to place the processor
- into 24 bitmode (although
-\emph on
-tinibios
-\emph default
- in the ds390 libraries will do that for you).
- If you don't use
-\emph on
-tinibios
-\emph default
-\begin_inset LatexCommand \index{Tinibios (DS390)}
+\begin_inset LatexCommand \index{\_\_endasm}
\end_inset
-, the boot loader or similar code must ensure that the processor is in 24
- bit contiguous addressing mode before calling the SDCC startup code.
-\newline
-
-\newline
-Like the
-\emph on
--
-\begin_inset ERT
-status Collapsed
-\layout Standard
+\size default
+;
+\family default
+ keyword pair.
+ Specifically it will not know which registers are used and thus register
+ pushing/popping
+\begin_inset LatexCommand \index{push/pop}
-\backslash
-/
\end_inset
--model-large
-\emph default
- option, variables will by default be placed into the XDATA segment.
+ has to be done manually.
-\newline
+\layout Standard
-\newline
-Segments may be placed anywhere in the 4 meg address space using the usual
- -
+It is recommended that each assembly instruction (including labels) be placed
+ in a separate line (as the example shows).
+ When the -
\begin_inset ERT
status Collapsed
/
\end_inset
--*-loc options.
- Note that if any segments are located above 64K, the -r flag must be passed
- to the linker to generate the proper segment relocations, and the Intel
- HEX output format must be used.
- The -r flag can be passed to the linker by using the option
+-
\emph on
--Wl-r
-\emph default
- on the SDCC command line.
- However, currently the linker can not handle code segments > 64k.
-\layout Section
-
-Pragmas
-\begin_inset LatexCommand \index{Pragmas}
+peep-asm
+\begin_inset LatexCommand \index{-\/-peep-asm}
\end_inset
-\layout Standard
-
-SDCC supports the following #pragma directives.
-\layout Itemize
-
-SAVE
-\begin_inset LatexCommand \index{\#pragma SAVE}
+\emph default
+ command line option is used, the inline assembler code will be passed through
+ the peephole optimizer
+\begin_inset LatexCommand \index{Peephole optimizer}
\end_inset
- - this will save all current options to the SAVE/RESTORE stack.
- See RESTORE.
-\layout Itemize
+.
+ There are only a few (if any) cases where this option makes sense, it might
+ cause some unexpected changes in the inline assembler code.
+ Please go through the peephole optimizer rules defined in file
+\emph on
+SDCCpeeph.def
+\emph default
+ before using this option.
+\layout Subsection
-RESTORE
-\begin_inset LatexCommand \index{\#pragma RESTORE}
+Naked Functions
+\begin_inset LatexCommand \label{sub:Naked-Functions}
\end_inset
- - will restore saved options from the last save.
- SAVEs & RESTOREs can be nested.
- SDCC uses a SAVE/RESTORE stack: SAVE pushes current options to the stack,
- RESTORE pulls current options from the stack.
- See SAVE.
-\layout Itemize
-NOGCSE
-\begin_inset LatexCommand \index{\#pragma NOGCSE}
+\begin_inset LatexCommand \index{Naked functions}
\end_inset
- - will stop global common subexpression elimination.
-\layout Itemize
-
-NOINDUCTION
-\begin_inset LatexCommand \index{\#pragma NOINDUCTION}
-
-\end_inset
- - will stop loop induction optimizations.
-\layout Itemize
+\layout Standard
-NOJTBOUND
-\begin_inset LatexCommand \index{\#pragma NOJTBOUND}
+A special keyword may be associated with a function declaring it as
+\emph on
+_naked
+\begin_inset LatexCommand \index{\_naked}
\end_inset
- - will not generate code for boundary value checking, when switch statements
- are turned into jump-tables (dangerous).
- For more details see section
-\begin_inset LatexCommand \ref{sub:'switch'-Statements}
+
+\begin_inset LatexCommand \index{\_\_naked}
\end_inset
.
-\layout Itemize
-
-NOOVERLAY
-\begin_inset LatexCommand \index{\#pragma NOOVERLAY}
+
+\emph default
+The
+\emph on
+_naked
+\emph default
+ function modifier attribute prevents the compiler from generating prologue
+\begin_inset LatexCommand \index{function prologue}
\end_inset
- - the compiler will not overlay the parameters and local variables of a
- function.
-\layout Itemize
-
-LESS_PEDANTIC
-\begin_inset LatexCommand \index{\#pragma LESS\_PEDANTIC}
+ and epilogue
+\begin_inset LatexCommand \index{function epilogue}
\end_inset
- - the compiler will not warn you anymore for obvious mistakes, you'r on
- your own now ;-(
-\layout Itemize
+ code for that function.
+ This means that the user is entirely responsible for such things as saving
+ any registers that may need to be preserved, selecting the proper register
+ bank, generating the
+\emph on
+return
+\emph default
+ instruction at the end, etc.
+ Practically, this means that the contents of the function must be written
+ in inline assembler.
+ This is particularly useful for interrupt functions, which can have a large
+ (and often unnecessary) prologue/epilogue.
+ For example, compare the code generated by these two functions:
+\layout Verse
-NOLOOPREVERSE
-\begin_inset LatexCommand \index{\#pragma NOLOOPREVERSE}
+
+\family typewriter
+volatile
+\begin_inset LatexCommand \index{volatile}
\end_inset
- - Will not do loop reversal optimization
-\layout Itemize
+ data unsigned char counter;
+\newline
-EXCLUDE
-\begin_inset LatexCommand \index{\#pragma EXCLUDE}
+\newline
+void simpleInterrupt(void) interrupt
+\begin_inset LatexCommand \index{interrupt}
\end_inset
- NONE | {acc[,b[,dpl[,dph]]] - The exclude pragma disables generation of
- pair of push/pop
-\begin_inset LatexCommand \index{push/pop}
-
-\end_inset
- instruction in ISR function (using interrupt
-\begin_inset LatexCommand \index{interrupt}
+\begin_inset LatexCommand \index{\_\_interrupt}
\end_inset
- keyword).
- The directive should be placed immediately before the ISR function definition
- and it affects ALL ISR functions following it.
- To enable the normal register saving for ISR functions use #pragma\SpecialChar ~
-EXCLUDE\SpecialChar ~
-none
-\begin_inset LatexCommand \index{\#pragma EXCLUDE}
+ 1
+\newline
+{
+\newline
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+counter++;
+\newline
+}
+\newline
+
+\newline
+void nakedInterrupt(void) interrupt 2 _naked
+\newline
+{
+\newline
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+_asm
+\begin_inset LatexCommand \index{\_asm}
\end_inset
-.
-\layout Itemize
-NOIV
-\begin_inset LatexCommand \index{\#pragma NOIV}
+\begin_inset LatexCommand \index{\_\_asm}
\end_inset
- - Do not generate interrupt vector table entries for all ISR functions
- defined after the pragma.
- This is useful in cases where the interrupt vector table must be defined
- manually, or when there is a secondary, manually defined interrupt vector
- table (e.g.
- for the autovector feature of the Cypress EZ-USB FX2).
- More elegantly this can be achieved by obmitting the optional interrupt
- number after the interrupt keyword, see section
-\begin_inset LatexCommand \ref{sub:Interrupt-Service-Routines}
+
+\newline
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+inc\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+_counter ; does not change flags, no need to save psw
+\newline
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+reti\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+; MUST explicitly include ret or reti in _naked function.
+\newline
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+_endasm
+\begin_inset LatexCommand \index{\_endasm}
\end_inset
-\SpecialChar ~
-about interrupts.
-\layout Itemize
-CALLEE-SAVES
-\begin_inset LatexCommand \index{\#pragma CALLEE-SAVES}
+\begin_inset LatexCommand \index{\_\_endasm}
\end_inset
+;
+\newline
+}
+\layout Standard
-\begin_inset LatexCommand \index{function prologue}
-
-\end_inset
-
- function1[,function2[,function3...]] - The compiler by default uses a caller
- saves convention for register saving across function calls, however this
- can cause unnecessary register pushing & popping when calling small functions
- from larger functions.
- This option can be used to switch off the register saving convention for
- the function names specified.
- The compiler will not save registers when calling these functions, extra
- code need to be manually inserted at the entry & exit for these functions
- to save & restore the registers used by these functions, this can SUBSTANTIALLY
- reduce code & improve run time performance of the generated code.
- In the future the compiler (with inter procedural analysis) may be able
- to determine the appropriate scheme to use for each function call.
- If -
-\begin_inset ERT
-status Collapsed
-
-\layout Standard
-
-\backslash
-/
-\end_inset
-
--callee-saves command line option is used, the function names specified
- in #pragma\SpecialChar ~
-CALLEE-SAVES
-\begin_inset LatexCommand \index{\#pragma CALLEE-SAVES}
-
-\end_inset
-
- is appended to the list of functions specified in the command line.
-\layout Standard
-
-The pragma's are intended to be used to turn-on or off certain optimizations
- which might cause the compiler to generate extra stack / data space to
- store compiler generated temporary variables.
- This usually happens in large functions.
- Pragma directives should be used as shown in the following example, they
- are used to control options & optimizations for a given function; pragmas
- should be placed before and/or after a function, placing pragma's inside
- a function body could have unpredictable results.
-\layout Verse
+For an 8051 target, the generated simpleInterrupt looks like:
+\layout Verse
\family typewriter
-#pragma SAVE
-\begin_inset LatexCommand \index{\#pragma SAVE}
-
-\end_inset
-
- \SpecialChar ~
+_simpleInterrupt:
+\newline
+\SpecialChar ~
\SpecialChar ~
\SpecialChar ~
\SpecialChar ~
+push\SpecialChar ~
\SpecialChar ~
\SpecialChar ~
\SpecialChar ~
-/* save the current settings */
+acc
\newline
-#pragma NOGCSE
-\begin_inset LatexCommand \index{\#pragma NOGCSE}
-
-\end_inset
-
- \SpecialChar ~
\SpecialChar ~
\SpecialChar ~
\SpecialChar ~
\SpecialChar ~
-/* turnoff global subexpression elimination */
+push\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+b
\newline
-#pragma NOINDUCTION
-\begin_inset LatexCommand \index{\#pragma NOINDUCTION}
-
-\end_inset
-
- /* turn off induction optimizations */
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+push\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+dpl
\newline
-int foo ()
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+push\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+dph
\newline
-{
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+push\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+psw
\newline
\SpecialChar ~
- \SpecialChar ~
- ...
-
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+mov\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+psw,#0x00
\newline
\SpecialChar ~
- \SpecialChar ~
- /* large code */
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+inc\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+_counter
\newline
\SpecialChar ~
- \SpecialChar ~
- ...
-
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+pop\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+psw
\newline
-}
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+pop\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+dph
\newline
-#pragma RESTORE
-\begin_inset LatexCommand \index{\#pragma RESTORE}
-
-\end_inset
-
- /* turn the optimizations back on */
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+pop\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+dpl
+\newline
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+pop\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+b
+\newline
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+pop\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+acc
+\newline
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+reti
\layout Standard
-The compiler will generate a warning message when extra space is allocated.
- It is strongly recommended that the SAVE and RESTORE pragma's be used when
- changing options for a function.
-\layout Section
-
-Defines Created by the Compiler
-\begin_inset LatexCommand \index{Defines created by the compiler}
-
-\end_inset
+whereas nakedInterrupt looks like:
+\layout Verse
+\family typewriter
+_nakedInterrupt:
+\newline
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+inc\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+_counter ; does not change flags, no need to save psw
+\newline
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+reti\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+; MUST explicitly include ret or reti in _naked function
\layout Standard
-The compiler creates the following #defines
-\begin_inset LatexCommand \index{\#defines}
+The related directive #pragma exclude
+\begin_inset LatexCommand \index{\#pragma exclude}
\end_inset
-:
-\newline
-
-\layout Standard
-
+ allows a more fine grained control over pushing & popping
+\begin_inset LatexCommand \index{push/pop}
-\begin_inset Tabular
-<lyxtabular version="3" rows="10" columns="2">
-<features>
-<column alignment="center" valignment="top" leftline="true" width="0">
-<column alignment="center" valignment="top" leftline="true" rightline="true" width="0">
-<row topline="true" bottomline="true">
-<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
-\begin_inset Text
+\end_inset
+ the registers.
\layout Standard
+While there is nothing preventing you from writing C code inside a
+\family typewriter
+_naked
+\family default
+ function, there are many ways to shoot yourself in the foot doing this,
+ and it is recommended that you stick to inline assembler.
+\layout Subsection
-\series bold
-#define
-\end_inset
-</cell>
-<cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
-\begin_inset Text
-
+Use of Labels within Inline Assembler
\layout Standard
+SDCC allows the use of in-line assembler with a few restrictions regarding
+ labels.
+ In older versions of the compiler all labels defined within inline assembler
+ code
+\emph on
+had to be
+\emph default
+ of the form
+\emph on
+nnnnn$
+\emph default
+ where nnnn is a number less than 100 (which implies a limit of utmost 100
+ inline assembler labels
+\emph on
+per function
+\emph default
+\noun on
+)
+\noun default
+.
+
+\layout Verse
-\series bold
-Description
-\end_inset
-</cell>
-</row>
-<row topline="true">
-<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
-\begin_inset Text
-
-\layout Standard
-SDCC
-\begin_inset LatexCommand \index{SDCC}
+\family typewriter
+_asm
+\begin_inset LatexCommand \index{\_asm}
+
+\end_inset
+
+
+\begin_inset LatexCommand \index{\_\_asm}
\end_inset
+\newline
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+mov\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+b,#10
+\newline
+00001$:
+\newline
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+djnz\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+b,00001$
+\newline
+_endasm
+\begin_inset LatexCommand \index{\_endasm}
+
\end_inset
-</cell>
-<cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
-\begin_inset Text
-\layout Standard
-this Symbol is always defined
+\begin_inset LatexCommand \index{\_\_endasm}
+
\end_inset
-</cell>
-</row>
-<row topline="true">
-<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
-\begin_inset Text
+ ;
\layout Standard
-SDCC_mcs51
-\begin_inset LatexCommand \index{SDCC\_mcs51}
+Inline assembler code cannot reference any C-Labels, however it can reference
+ labels
+\begin_inset LatexCommand \index{Labels}
\end_inset
- or SDCC_ds390
-\begin_inset LatexCommand \index{SDCC\_ds390}
+ defined by the inline assembler, e.g.:
+\layout Verse
-\end_inset
- or SDCC_z80
-\begin_inset LatexCommand \index{SDCC\_z80}
+\family typewriter
+foo() {
+\newline
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+/* some c code */
+\newline
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+_asm
+\newline
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+; some assembler code
+\newline
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+ljmp $0003
+\newline
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+_endasm;
+\newline
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+/* some more c code */
+\newline
+clabel:\SpecialChar ~
+\SpecialChar ~
+/* inline assembler cannot reference this label */
+\newline
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+_asm
+\newline
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+$0003: ;label (can be referenced by inline assembler only)
+\newline
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+_endasm
+\begin_inset LatexCommand \index{\_endasm}
\end_inset
-, etc
-\end_inset
-</cell>
-<cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
-\begin_inset Text
-\layout Standard
+\begin_inset LatexCommand \index{\_\_endasm}
-depending on the model used (e.g.: -mds390
\end_inset
-</cell>
-</row>
-<row topline="true">
-<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
-\begin_inset Text
+ ;
+\newline
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+/* some more c code */
+\newline
+}
\layout Standard
-__mcs51
-\begin_inset LatexCommand \index{\_\_mcs51}
-
-\end_inset
+In other words inline assembly code can access labels defined in inline
+ assembly within the scope of the function.
+ The same goes the other way, i.e.
+ labels defines in inline assembly can not be accessed by C statements.
+\layout Section
-, __ds390
-\begin_inset LatexCommand \index{\_\_ds390}
+Interfacing with Assembler Code
+\begin_inset LatexCommand \index{Assembler routines}
\end_inset
-, __hc08
-\begin_inset LatexCommand \index{\_\_hc08}
-\end_inset
+\layout Subsection
-, __z80
-\begin_inset LatexCommand \index{\_\_z80}
+Global Registers used for Parameter Passing
+\begin_inset LatexCommand \index{Parameter passing}
\end_inset
-, etc
-\end_inset
-</cell>
-<cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
-\begin_inset Text
\layout Standard
-depending on the model used (e.g.
- -mz80)
+The compiler always uses the global registers
+\emph on
+DPL, DPH
+\begin_inset LatexCommand \index{DPTR, DPH, DPL}
+
\end_inset
-</cell>
-</row>
-<row topline="true">
-<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
-\begin_inset Text
-\layout Standard
-SDCC_STACK_AUTO
-\begin_inset LatexCommand \index{SDCC\_STACK\_AUTO}
+\begin_inset LatexCommand \index{DPTR}
\end_inset
+, B
+\begin_inset LatexCommand \index{B (mcs51, ds390 register)}
\end_inset
-</cell>
-<cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
-\begin_inset Text
-
-\layout Standard
-when
+
+\emph default
+and
\emph on
--
+ ACC
+\begin_inset LatexCommand \index{ACC (mcs51, ds390 register)}
+
+\end_inset
+
+
+\emph default
+ to pass the first parameter to a routine.
+ The second parameter onwards is either allocated on the stack (for reentrant
+ routines or if -
\begin_inset ERT
status Collapsed
/
\end_inset
--stack-auto
-\emph default
- option is used
-\end_inset
-</cell>
-</row>
-<row topline="true">
-<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
-\begin_inset Text
+-stack-auto is used) or in data / xdata memory (depending on the memory
+ model).
+
+\layout Subsection
+Assembler Routine (non-reentrant)
\layout Standard
-SDCC_MODEL_SMALL
-\begin_inset LatexCommand \index{SDCC\_MODEL\_SMALL}
+In the following example
+\begin_inset LatexCommand \index{reentrant}
\end_inset
+\begin_inset LatexCommand \index{Assembler routines (non-reentrant)}
+
\end_inset
-</cell>
-<cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
-\begin_inset Text
-\layout Standard
+ the function c_func calls an assembler routine asm_func, which takes two
+ parameters
+\begin_inset LatexCommand \index{function parameter}
-when
-\emph on
--
-\begin_inset ERT
-status Collapsed
+\end_inset
-\layout Standard
+.
+\layout Verse
-\backslash
-/
-\end_inset
--model-small
-\emph default
- is used
-\end_inset
-</cell>
-</row>
-<row topline="true">
-<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
-\begin_inset Text
+\family typewriter
+extern int asm_func(unsigned char, unsigned char);
+\newline
+
+\newline
+int c_func (unsigned char i, unsigned char j)
+\newline
+{
+\newline
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+return asm_func(i,j);
+\newline
+}
+\newline
+\newline
+int main()
+\newline
+{
+\newline
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+return c_func(10,9);
+\newline
+}
\layout Standard
-SDCC_MODEL_LARGE
-\begin_inset LatexCommand \index{SDCC\_MODEL\_LARGE}
+The corresponding assembler function is:
+\layout Verse
-\end_inset
+\family typewriter
+.globl _asm_func_PARM_2
+\newline
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+.globl _asm_func
+\newline
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+.area OSEG
+\newline
+_asm_func_PARM_2:
+\newline
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+.ds 1
+\newline
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+.area CSEG
+\newline
+_asm_func:
+\newline
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+mov\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+a,dpl
+\newline
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+add\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+a,_asm_func_PARM_2
+\newline
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+mov\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+dpl,a
+\newline
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+mov\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+dph
+\begin_inset LatexCommand \index{DPTR, DPH, DPL}
\end_inset
-</cell>
-<cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
-\begin_inset Text
-
-\layout Standard
-
-when
-\emph on
--
-\begin_inset ERT
-status Collapsed
+,#0x00
+\newline
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+ret
\layout Standard
-\backslash
-/
-\end_inset
+Note here that the return values
+\begin_inset LatexCommand \index{return value}
--model-large
-\emph default
- is used
\end_inset
-</cell>
-</row>
-<row topline="true">
-<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
-\begin_inset Text
+ are placed in 'dpl' - One byte return value, 'dpl' LSB & 'dph' MSB for
+ two byte values.
+ 'dpl', 'dph' and 'b' for three byte values (generic pointers) and 'dpl','dph','
+b' & 'acc' for four byte values.
\layout Standard
-SDCC_USE_XSTACK
-\begin_inset LatexCommand \index{SDCC\_USE\_XSTACK}
-
+The parameter naming convention is _<function_name>_PARM_<n>, where n is
+ the parameter number starting from 1, and counting from the left.
+ The first parameter is passed in
+\begin_inset Quotes eld
\end_inset
+dpl
+\begin_inset Quotes erd
+\end_inset
+ for a one byte parameter,
+\begin_inset Quotes eld
\end_inset
-</cell>
-<cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
-\begin_inset Text
-\layout Standard
+dptr
+\begin_inset Quotes erd
+\end_inset
-when
-\emph on
--
-\begin_inset ERT
-status Collapsed
+ for two bytes,
+\begin_inset Quotes eld
+\end_inset
-\layout Standard
+b,dptr
+\begin_inset Quotes erd
+\end_inset
-\backslash
-/
+ for three bytes and
+\begin_inset Quotes eld
\end_inset
--xstack
-\emph default
- option is used
+acc,b,dptr
+\begin_inset Quotes erd
\end_inset
-</cell>
-</row>
-<row topline="true">
-<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
-\begin_inset Text
-\layout Standard
+ for a four bytes parameter.
+ The variable name for the second parameter will be _<function_name>_PARM_2.
+\newline
-SDCC_STACK_TENBIT
-\begin_inset LatexCommand \index{SDCC\_STACK\_TENBIT}
+\newline
+Assemble the assembler routine with the following command:
+\newline
-\end_inset
+\newline
-
-\end_inset
-</cell>
-<cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
-\begin_inset Text
+\family sans
+\series bold
+asx8051 -losg asmfunc.asm
+\newline
-\layout Standard
+\newline
-when
-\emph on
--mds390
-\emph default
- is used
-\end_inset
-</cell>
-</row>
-<row topline="true" bottomline="true">
-<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
-\begin_inset Text
+\family default
+\series default
+Then compile and link the assembler routine to the C source file with the
+ following command:
+\newline
+\newline
+
+\family sans
+\series bold
+sdcc cfunc.c asmfunc.rel
+\layout Subsection
+
+Assembler Routine (reentrant)
\layout Standard
-SDCC_MODEL_FLAT24
-\begin_inset LatexCommand \index{SDCC\_MODEL\_FLAT24}
+In this case
+\begin_inset LatexCommand \index{reentrant}
\end_inset
+\begin_inset LatexCommand \index{Assembler routines (reentrant)}
+
\end_inset
-</cell>
-<cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
-\begin_inset Text
-\layout Standard
+ the second parameter
+\begin_inset LatexCommand \index{function parameter}
-when
-\emph on
--mds390
-\emph default
- is used
\end_inset
-</cell>
-</row>
-</lyxtabular>
-\end_inset
+ onwards will be passed on the stack, the parameters are pushed from right
+ to left i.e.
+ after the call the leftmost parameter will be on the top of the stack.
+ Here is an example:
+\layout Verse
+\family typewriter
+extern int asm_func(unsigned char, unsigned char);
\newline
-\layout Chapter
+\newline
+int c_func (unsigned char i, unsigned char j) reentrant
+\newline
+{
+\newline
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+return asm_func(i,j);
+\newline
+}
+\newline
-Debugging with SDCDB
-\begin_inset LatexCommand \index{sdcdb}
+\newline
+int main()
+\newline
+{
+\newline
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+return c_func(10,9);
+\newline
+}
+\layout Standard
-\end_inset
+The corresponding assembler routine is:
+\layout Verse
-
+
+\family typewriter
+.globl _asm_func
+\newline
+_asm_func:
+\newline
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+push _bp
+\newline
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+mov _bp,sp
+\newline
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+mov r2,dpl
+\newline
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+mov a,_bp
+\newline
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+add a,#0xfd
+\newline
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+mov r0,a
+\newline
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+add a,#0xfc ;?
+\newline
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+mov r1,a
+\newline
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+mov a,@r0
+\newline
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+add a,r2 ;?
+\newline
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+mov dpl,a
+\newline
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+mov dph,#0x00
+\newline
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+mov sp,_bp
+\newline
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+pop _bp
+\newline
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+ret
\layout Standard
-SDCC is distributed with a source level debugger
-\begin_inset LatexCommand \index{Debugger}
+The compiling and linking procedure remains the same, however note the extra
+ entry & exit linkage required for the assembler code, _bp is the stack
+ frame pointer and is used to compute the offset into the stack for parameters
+ and local variables.
+\layout Section
+
+int (16 bit)
+\begin_inset LatexCommand \index{int (16 bit)}
\end_inset
-.
- The debugger uses a command line interface, the command repertoire of the
- debugger has been kept as close to gdb
-\begin_inset LatexCommand \index{gdb}
+ and long (32 bit)
+\begin_inset LatexCommand \index{long (32 bit)}
\end_inset
- (the GNU debugger) as possible.
- The configuration and build process is part of the standard compiler installati
-on, which also builds and installs the debugger in the target directory
- specified during configuration.
- The debugger allows you debug BOTH at the C source and at the ASM source
- level.
- Sdcdb is available on Unix platforms only.
-\layout Section
-
-Compiling for Debugging
+ Support
\layout Standard
-The \SpecialChar \-
-\SpecialChar \-
-debug option must be specified for all files for which debug information
- is to be generated.
- The complier generates a .adb file for each of these files.
- The linker creates the .cdb file from the .adb files and the address information.
- This .cdb is used by the debugger.
-\layout Section
+For signed & unsigned int (16 bit) and long (32 bit) variables, division,
+ multiplication and modulus operations are implemented by support routines.
+ These support routines are all developed in ANSI-C to facilitate porting
+ to other MCUs, although some model specific assembler optimizations are
+ used.
+ The following files contain the described routines, all of them can be
+ found in <installdir>/share/sdcc/lib.
+\newline
-How the Debugger Works
\layout Standard
+\align center
-When the -
-\begin_inset ERT
-status Collapsed
+\begin_inset Tabular
+<lyxtabular version="3" rows="11" columns="2">
+<features>
+<column alignment="center" valignment="top" leftline="true" width="0">
+<column alignment="center" valignment="top" leftline="true" rightline="true" width="0">
+<row topline="true" bottomline="true">
+<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
+\begin_inset Text
\layout Standard
-\backslash
-/
-\end_inset
--debug option is specified the compiler generates extra symbol information
- some of which are put into the assembler source and some are put into the
- .adb file.
- Then the linker creates the .cdb file from the individual .adb files with
- the address information for the symbols.
- The debugger reads the symbolic information generated by the compiler &
- the address information generated by the linker.
- It uses the SIMULATOR (Daniel's S51) to execute the program, the program
- execution is controlled by the debugger.
- When a command is issued for the debugger, it translates it into appropriate
- commands for the simulator.
-\layout Section
+\series bold
+Function
+\end_inset
+</cell>
+<cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
+\begin_inset Text
-Starting the Debugger
\layout Standard
-The debugger can be started using the following command line.
- (Assume the file you are debugging has the file name foo).
-\newline
-
-\newline
-\family sans
\series bold
-sdcdb foo
-\newline
-
-\family default
-\series default
-
-\newline
-The debugger will look for the following files.
-\layout Itemize
-
-foo.c - the source file.
-\layout Itemize
-
-foo.cdb - the debugger symbol information file.
-\layout Itemize
+Description
+\end_inset
+</cell>
+</row>
+<row topline="true">
+<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
+\begin_inset Text
-foo.ihx - the Intel hex format
-\begin_inset LatexCommand \index{Intel hex format}
+\layout Standard
+_mulint.c
\end_inset
+</cell>
+<cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
+\begin_inset Text
- object file.
-\layout Section
-
-Command Line Options.
-\layout Itemize
+\layout Standard
--
-\begin_inset ERT
-status Collapsed
+16 bit multiplication
+\end_inset
+</cell>
+</row>
+<row topline="true">
+<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
+\begin_inset Text
\layout Standard
-\backslash
-/
+_divsint.c
\end_inset
-
--directory=<source file directory> this option can used to specify the directory
- search list.
- The debugger will look into the directory list specified for source, cdb
- & ihx files.
- The items in the directory list must be separated by ':', e.g.
- if the source files can be in the directories /home/src1 and /home/src2,
- the -
-\begin_inset ERT
-status Collapsed
+</cell>
+<cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
+\begin_inset Text
\layout Standard
-\backslash
-/
+ signed 16 bit division (calls _divuint)
\end_inset
-
--directory option should be -
-\begin_inset ERT
-status Collapsed
+</cell>
+</row>
+<row topline="true">
+<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
+\begin_inset Text
\layout Standard
-\backslash
-/
+_divuint.c
\end_inset
+</cell>
+<cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
+\begin_inset Text
--directory=/home/src1:/home/src2.
- Note there can be no spaces in the option.
-
-\layout Itemize
-
--cd <directory> - change to the <directory>.
-\layout Itemize
+\layout Standard
--fullname - used by GUI front ends.
-\layout Itemize
+ unsigned 16 bit division
+\end_inset
+</cell>
+</row>
+<row topline="true">
+<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
+\begin_inset Text
--cpu <cpu-type> - this argument is passed to the simulator please see the
- simulator docs for details.
-\layout Itemize
+\layout Standard
--X <Clock frequency > this options is passed to the simulator please see
- the simulator docs for details.
-\layout Itemize
+_modsint.c
+\end_inset
+</cell>
+<cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
+\begin_inset Text
--s <serial port file> passed to simulator see the simulator docs for details.
-\layout Itemize
+\layout Standard
--S <serial in,out> passed to simulator see the simulator docs for details.
-\layout Section
+signed 16 bit modulus (calls _moduint)
+\end_inset
+</cell>
+</row>
+<row topline="true">
+<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
+\begin_inset Text
-Debugger Commands.
\layout Standard
-As mentioned earlier the command interface for the debugger has been deliberatel
-y kept as close the GNU debugger gdb, as possible.
- This will help the integration with existing graphical user interfaces
- (like ddd, xxgdb or xemacs) existing for the GNU debugger.
- If you use a graphical user interface for the debugger you can skip the
- next sections.
-\layout Subsubsection*
+_moduint.c
+\end_inset
+</cell>
+<cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
+\begin_inset Text
-break [line | file:line | function | file:function]
\layout Standard
-Set breakpoint at specified line or function:
-\newline
+unsigned 16 bit modulus
+\end_inset
+</cell>
+</row>
+<row topline="true">
+<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
+\begin_inset Text
-\newline
+\layout Standard
-\family sans
-\series bold
-sdcdb>break 100
-\newline
-sdcdb>break foo.c:100
-\newline
-sdcdb>break funcfoo
-\newline
-sdcdb>break foo.c:funcfoo
-\layout Subsubsection*
+_mullong.c
+\end_inset
+</cell>
+<cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
+\begin_inset Text
-clear [line | file:line | function | file:function ]
\layout Standard
-Clear breakpoint at specified line or function:
-\newline
+32 bit multiplication
+\end_inset
+</cell>
+</row>
+<row topline="true">
+<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
+\begin_inset Text
-\newline
+\layout Standard
-\family sans
-\series bold
-sdcdb>clear 100
-\newline
-sdcdb>clear foo.c:100
-\newline
-sdcdb>clear funcfoo
-\newline
-sdcdb>clear foo.c:funcfoo
-\layout Subsubsection*
+_divslong.c
+\end_inset
+</cell>
+<cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
+\begin_inset Text
-continue
\layout Standard
-Continue program being debugged, after breakpoint.
-\layout Subsubsection*
+ signed 32 division (calls _divulong)
+\end_inset
+</cell>
+</row>
+<row topline="true">
+<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
+\begin_inset Text
-finish
\layout Standard
-Execute till the end of the current function.
-\layout Subsubsection*
+_divulong.c
+\end_inset
+</cell>
+<cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
+\begin_inset Text
-delete [n]
\layout Standard
-Delete breakpoint number 'n'.
- If used without any option clear ALL user defined break points.
-\layout Subsubsection*
-
-info [break | stack | frame | registers ]
-\layout Itemize
+unsigned 32 division
+\end_inset
+</cell>
+</row>
+<row topline="true">
+<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
+\begin_inset Text
-info break - list all breakpoints
-\layout Itemize
+\layout Standard
-info stack - show the function call stack.
-\layout Itemize
+_modslong.c
+\end_inset
+</cell>
+<cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
+\begin_inset Text
-info frame - show information about the current execution frame.
-\layout Itemize
+\layout Standard
-info registers - show content of all registers.
-\layout Subsubsection*
+ signed 32 bit modulus (calls _modulong)
+\end_inset
+</cell>
+</row>
+<row topline="true" bottomline="true">
+<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
+\begin_inset Text
-step
\layout Standard
-Step program until it reaches a different source line.
-\layout Subsubsection*
+_modulong.c
+\end_inset
+</cell>
+<cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
+\begin_inset Text
-next
\layout Standard
-Step program, proceeding through subroutine calls.
-\layout Subsubsection*
+unsigned 32 bit modulus
+\end_inset
+</cell>
+</row>
+</lyxtabular>
-run
-\layout Standard
+\end_inset
-Start debugged program.
-\layout Subsubsection*
-ptype variable
-\layout Standard
+\newline
-Print type information of the variable.
-\layout Subsubsection*
+\layout Standard
-print variable
-\layout Standard
+Since they are compiled as
+\emph on
+non-reentrant
+\emph default
-print value of variable.
-\layout Subsubsection*
+\begin_inset LatexCommand \index{reentrant}
-file filename
-\layout Standard
+\end_inset
-load the given file name.
- Note this is an alternate method of loading file for debugging.
-\layout Subsubsection*
+, interrupt
+\begin_inset LatexCommand \index{interrupt}
-frame
-\layout Standard
+\end_inset
-print information about current frame.
-\layout Subsubsection*
+ service routines should not do any of the above operations.
+ If this is unavoidable then the above routines will need to be compiled
+ with the
+\emph on
+-
+\begin_inset ERT
+status Collapsed
-set srcmode
\layout Standard
-Toggle between C source & assembly source.
-\layout Subsubsection*
+\backslash
+/
+\end_inset
-! simulator command
-\layout Standard
+-stack-auto
+\begin_inset LatexCommand \index{-\/-stack-auto}
-Send the string following '!' to the simulator, the simulator response is
- displayed.
- Note the debugger does not interpret the command being sent to the simulator,
- so if a command like 'go' is sent the debugger can loose its execution
- context and may display incorrect values.
-\layout Subsubsection*
+\end_inset
+
+
+\emph default
+ option, after which the source program will have to be compiled with
+\emph on
+-
+\begin_inset ERT
+status Collapsed
-quit.
\layout Standard
-"Watch me now.
- Iam going Down.
- My name is Bobby Brown"
-\layout Section
+\backslash
+/
+\end_inset
-Interfacing with XEmacs
-\begin_inset LatexCommand \index{XEmacs}
+-int-long-reent
+\begin_inset LatexCommand \index{-\/-int-long-reent}
\end_inset
-\begin_inset LatexCommand \index{Emacs}
+\emph default
+ option.
+ Notice that you don't have to call these routines directly.
+ The compiler will use them automatically every time an integer operation
+ is required.
+\layout Section
+
+Floating Point Support
+\begin_inset LatexCommand \index{Floating point support}
\end_inset
-.
+
\layout Standard
-Two files (in emacs lisp) are provided for the interfacing with XEmacs,
- sdcdb.el and sdcdbsrc.el.
- These two files can be found in the $(prefix)/bin directory after the installat
-ion is complete.
- These files need to be loaded into XEmacs for the interface to work.
- This can be done at XEmacs startup time by inserting the following into
- your '.xemacs' file (which can be found in your HOME directory):
+SDCC supports IEEE (single precision 4 bytes) floating point numbers.The
+ floating point support routines are derived from gcc's floatlib.c and consist
+ of the following routines:
\newline
-\newline
+\layout Standard
+\align center
-\family typewriter
-(load-file sdcdbsrc.el)
-\family default
+\size footnotesize
-\newline
+\begin_inset Tabular
+<lyxtabular version="3" rows="17" columns="2">
+<features>
+<column alignment="center" valignment="top" leftline="true" width="0">
+<column alignment="center" valignment="top" leftline="true" rightline="true" width="0">
+<row topline="true" bottomline="true">
+<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
+\begin_inset Text
-\newline
-.xemacs is a lisp file so the () around the command is REQUIRED.
- The files can also be loaded dynamically while XEmacs is running, set the
- environment variable 'EMACSLOADPATH' to the installation bin directory
- (<installdir>/bin), then enter the following command ESC-x load-file sdcdbsrc.
- To start the interface enter the following command:
-\newline
+\layout Standard
-\newline
-\family sans
-\series bold
-ESC-x sdcdbsrc
-\family default
-\series default
+\family roman
+\series medium
+\shape up
+\size normal
+\emph off
+\bar no
+\noun off
+\color none
+Function
+\end_inset
+</cell>
+<cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
+\begin_inset Text
-\newline
+\layout Standard
-\newline
-You will prompted to enter the file name to be debugged.
-
-\newline
+Description
+\end_inset
+</cell>
+</row>
+<row topline="true">
+<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
+\begin_inset Text
-\newline
-The command line options that are passed to the simulator directly are bound
- to default values in the file sdcdbsrc.el.
- The variables are listed below, these values maybe changed as required.
-\layout Itemize
+\layout Standard
-sdcdbsrc-cpu-type '51
-\layout Itemize
-sdcdbsrc-frequency '11059200
-\layout Itemize
+\family roman
+\series medium
+\shape up
+\size normal
+\emph off
+\bar no
+\noun off
+\color none
+_fsadd.c
+\end_inset
+</cell>
+<cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
+\begin_inset Text
-sdcdbsrc-serial nil
\layout Standard
-The following is a list of key mapping for the debugger interface.
+
+\family roman
+\series medium
+\shape up
+\size normal
+\emph off
+\bar no
+\noun off
+\color none
+add floating point numbers
+\end_inset
+</cell>
+</row>
+<row topline="true">
+<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
+\begin_inset Text
+
\layout Standard
-\SpecialChar ~
-\family typewriter
+\family roman
+\series medium
+\shape up
+\size normal
+\emph off
+\bar no
+\noun off
+\color none
+_fssub.c
+\end_inset
+</cell>
+<cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
+\begin_inset Text
-\newline
-;; Current Listing ::
-\newline
-;;key\SpecialChar ~
-\SpecialChar ~
-\SpecialChar ~
-\SpecialChar ~
-\SpecialChar ~
-\SpecialChar ~
-\SpecialChar ~
-\SpecialChar ~
-\SpecialChar ~
-\SpecialChar ~
-\SpecialChar ~
-\SpecialChar ~
-\SpecialChar ~
-\SpecialChar ~
-\SpecialChar ~
-binding\SpecialChar ~
-\SpecialChar ~
-\SpecialChar ~
-\SpecialChar ~
-\SpecialChar ~
-\SpecialChar ~
-\SpecialChar ~
-\SpecialChar ~
-\SpecialChar ~
-\SpecialChar ~
-\SpecialChar ~
-\SpecialChar ~
-\SpecialChar ~
-\SpecialChar ~
-\SpecialChar ~
-\SpecialChar ~
-\SpecialChar ~
-\SpecialChar ~
-\SpecialChar ~
-\SpecialChar ~
-\SpecialChar ~
-\SpecialChar ~
-Comment
-\newline
-;;---\SpecialChar ~
-\SpecialChar ~
-\SpecialChar ~
-\SpecialChar ~
-\SpecialChar ~
-\SpecialChar ~
-\SpecialChar ~
-\SpecialChar ~
-\SpecialChar ~
-\SpecialChar ~
-\SpecialChar ~
-\SpecialChar ~
-\SpecialChar ~
-\SpecialChar ~
-\SpecialChar ~
-------\SpecialChar ~
-\SpecialChar ~
+\layout Standard
+
+
+\family roman
+\series medium
+\shape up
+\size normal
+\emph off
+\bar no
+\noun off
+\color none
+subtract floating point numbers
+\end_inset
+</cell>
+</row>
+<row topline="true">
+<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
+\begin_inset Text
+
+\layout Standard
+
+
+\family roman
+\series medium
+\shape up
+\size normal
+\emph off
+\bar no
+\noun off
+\color none
+_fsdiv.c
+\end_inset
+</cell>
+<cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
+\begin_inset Text
+
+\layout Standard
+
+
+\family roman
+\series medium
+\shape up
+\size normal
+\emph off
+\bar no
+\noun off
+\color none
+divide floating point numbers
+\end_inset
+</cell>
+</row>
+<row topline="true">
+<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
+\begin_inset Text
+
+\layout Standard
+
+
+\family roman
+\series medium
+\shape up
+\size normal
+\emph off
+\bar no
+\noun off
+\color none
+_fsmul.c
+\end_inset
+</cell>
+<cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
+\begin_inset Text
+
+\layout Standard
+
+
+\family roman
+\series medium
+\shape up
+\size normal
+\emph off
+\bar no
+\noun off
+\color none
+multiply floating point numbers
+\end_inset
+</cell>
+</row>
+<row topline="true">
+<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
+\begin_inset Text
+
+\layout Standard
+
+
+\family roman
+\series medium
+\shape up
+\size normal
+\emph off
+\bar no
+\noun off
+\color none
+_fs2uchar.c
+\end_inset
+</cell>
+<cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
+\begin_inset Text
+
+\layout Standard
+
+
+\family roman
+\series medium
+\shape up
+\size normal
+\emph off
+\bar no
+\noun off
+\color none
+convert floating point to unsigned char
+\end_inset
+</cell>
+</row>
+<row topline="true">
+<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
+\begin_inset Text
+
+\layout Standard
+
+
+\family roman
+\series medium
+\shape up
+\size normal
+\emph off
+\bar no
+\noun off
+\color none
+_fs2char.c
+\end_inset
+</cell>
+<cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
+\begin_inset Text
+
+\layout Standard
+
+
+\family roman
+\series medium
+\shape up
+\size normal
+\emph off
+\bar no
+\noun off
+\color none
+convert floating point to signed char
+\end_inset
+</cell>
+</row>
+<row topline="true">
+<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
+\begin_inset Text
+
+\layout Standard
+
+
+\family roman
+\series medium
+\shape up
+\size normal
+\emph off
+\bar no
+\noun off
+\color none
+_fs2uint.c
+\end_inset
+</cell>
+<cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
+\begin_inset Text
+
+\layout Standard
+
+
+\family roman
+\series medium
+\shape up
+\size normal
+\emph off
+\bar no
+\noun off
+\color none
+convert floating point to unsigned int
+\end_inset
+</cell>
+</row>
+<row topline="true">
+<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
+\begin_inset Text
+
+\layout Standard
+
+
+\family roman
+\series medium
+\shape up
+\size normal
+\emph off
+\bar no
+\noun off
+\color none
+_fs2int.c
+\end_inset
+</cell>
+<cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
+\begin_inset Text
+
+\layout Standard
+
+
+\family roman
+\series medium
+\shape up
+\size normal
+\emph off
+\bar no
+\noun off
+\color none
+convert floating point to signed int
+\end_inset
+</cell>
+</row>
+<row topline="true">
+<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
+\begin_inset Text
+
+\layout Standard
+
+
+\family roman
+\series medium
+\shape up
+\size normal
+\emph off
+\bar no
+\noun off
+\color none
+_fs2ulong.
+\family default
+\series default
+\shape default
+\size default
+\emph default
+\bar default
+\noun default
+\color default
+c
+\end_inset
+</cell>
+<cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
+\begin_inset Text
+
+\layout Standard
+
+
+\family roman
+\series medium
+\shape up
+\size normal
+\emph off
+\bar no
+\noun off
+\color none
+convert floating point to unsigned long
+\end_inset
+</cell>
+</row>
+<row topline="true">
+<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
+\begin_inset Text
+
+\layout Standard
+
+
+\family roman
+\series medium
+\shape up
+\size normal
+\emph off
+\bar no
+\noun off
+\color none
+_fs2long.c
+\end_inset
+</cell>
+<cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
+\begin_inset Text
+
+\layout Standard
+
+
+\family roman
+\series medium
+\shape up
+\size normal
+\emph off
+\bar no
+\noun off
+\color none
+convert floating point to signed long
+\end_inset
+</cell>
+</row>
+<row topline="true">
+<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
+\begin_inset Text
+
+\layout Standard
+
+
+\family roman
+\series medium
+\shape up
+\size normal
+\emph off
+\bar no
+\noun off
+\color none
+_uchar2fs.c
+\end_inset
+</cell>
+<cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
+\begin_inset Text
+
+\layout Standard
+
+
+\family roman
+\series medium
+\shape up
+\size normal
+\emph off
+\bar no
+\noun off
+\color none
+convert unsigned char to floating point
+\end_inset
+</cell>
+</row>
+<row topline="true">
+<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
+\begin_inset Text
+
+\layout Standard
+
+
+\family roman
+\series medium
+\shape up
+\size normal
+\emph off
+\bar no
+\noun off
+\color none
+_char2fs.c
+\end_inset
+</cell>
+<cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
+\begin_inset Text
+
+\layout Standard
+
+
+\family roman
+\series medium
+\shape up
+\size normal
+\emph off
+\bar no
+\noun off
+\color none
+convert char to floating point number
+\end_inset
+</cell>
+</row>
+<row topline="true">
+<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
+\begin_inset Text
+
+\layout Standard
+
+
+\family roman
+\series medium
+\shape up
+\size normal
+\emph off
+\bar no
+\noun off
+\color none
+_uint2fs.c
+\end_inset
+</cell>
+<cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
+\begin_inset Text
+
+\layout Standard
+
+
+\family roman
+\series medium
+\shape up
+\size normal
+\emph off
+\bar no
+\noun off
+\color none
+convert unsigned int to floating point
+\end_inset
+</cell>
+</row>
+<row topline="true">
+<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
+\begin_inset Text
+
+\layout Standard
+
+
+\family roman
+\series medium
+\shape up
+\size normal
+\emph off
+\bar no
+\noun off
+\color none
+_int2fs.c
+\end_inset
+</cell>
+<cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
+\begin_inset Text
+
+\layout Standard
+
+
+\family roman
+\series medium
+\shape up
+\size normal
+\emph off
+\bar no
+\noun off
+\color none
+convert int to floating point numbers
+\end_inset
+</cell>
+</row>
+<row topline="true">
+<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
+\begin_inset Text
+
+\layout Standard
+
+
+\family roman
+\series medium
+\shape up
+\size normal
+\emph off
+\bar no
+\noun off
+\color none
+_ulong2fs.c
+\end_inset
+</cell>
+<cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
+\begin_inset Text
+
+\layout Standard
+
+
+\family roman
+\series medium
+\shape up
+\size normal
+\emph off
+\bar no
+\noun off
+\color none
+convert unsigned long to floating point number
+\end_inset
+</cell>
+</row>
+<row topline="true" bottomline="true">
+<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
+\begin_inset Text
+
+\layout Standard
+
+
+\family roman
+\series medium
+\shape up
+\size normal
+\emph off
+\bar no
+\noun off
+\color none
+_long2fs.c
+\end_inset
+</cell>
+<cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
+\begin_inset Text
+
+\layout Standard
+
+
+\family roman
+\series medium
+\shape up
+\size normal
+\emph off
+\bar no
+\noun off
+\color none
+convert long to floating point number
+\end_inset
+</cell>
+</row>
+</lyxtabular>
+
+\end_inset
+
+
+\newline
+
+\layout Standard
+
+These support routines are developed in ANSI-C so there is room for space
+ and speed improvement
+\begin_inset Foot
+collapsed false
+
+\layout Standard
+
+The floating point routines for the mcs51 are implemented in assembler
+\end_inset
+
+.
+ Note if all these routines are used simultaneously the data space might
+ overflow.
+ For serious floating point usage the large model might be needed.
+ Also notice that you don't have to call this routines directly.
+ The compiler will use them automatically every time a floating point operation
+ is required.
+\layout Section
+
+Library Routines
+\begin_inset LatexCommand \index{Libraries}
+
+\end_inset
+
+
+\layout Standard
+
+
+\emph on
+<pending: this is messy and incomplete - a little more information is in
+ sdcc/doc/libdoc.txt
+\emph default
+ >
+\layout Subsection
+
+Compiler support routines (_gptrget, _mulint etc.)
+\layout Subsection
+
+Stdclib functions (puts, printf, strcat etc.)
+\layout Subsubsection
+
+<stdio.h>
+\layout Standard
+
+
+\begin_inset LatexCommand \index{<stdio.h>}
+
+\end_inset
+
+As usual on embedded systems you have to provide your own
+\family typewriter
+getchar()
+\begin_inset LatexCommand \index{getchar()}
+
+\end_inset
+
+
+\family default
+and
+\family typewriter
+putchar()
+\begin_inset LatexCommand \index{putchar()}
+
+\end_inset
+
+
+\family default
+ routines.
+ SDCC does not know whether the system connects to a serial line with or
+ without handshake, LCD, keyboard or other device.
+ You'll find examples for serial routines f.e.
+ in sdcc/device/lib.
+\layout Standard
+
+The default
+\family typewriter
+ printf()
+\begin_inset LatexCommand \index{printf()}
+
+\end_inset
+
+
+\family default
+implementation in
+\family typewriter
+ printf_large.c
+\family default
+ does not support float (except on ds390).
+ To enable this recompile it with the option
+\emph on
+-
+\begin_inset ERT
+status Collapsed
+
+\layout Standard
+
+\backslash
+/
+\end_inset
+
+DUSE_FLOATS=1
+\begin_inset LatexCommand \index{USE\_FLOATS}
+
+\end_inset
+
+
+\emph default
+ on the command line.
+ Use
+\emph on
+-
+\begin_inset ERT
+status Collapsed
+
+\layout Standard
+
+\backslash
+/
+\end_inset
+
+-model-large
+\begin_inset LatexCommand \index{-\/-model-large}
+
+\end_inset
+
+
+\emph default
+ for the mcs51 port, since this uses a lot of memory.
+\layout Standard
+
+If you're short on memory you might want to use
+\family typewriter
+printf_small()
+\begin_inset LatexCommand \index{printf\_small()}
+
+\end_inset
+
+
+\family default
+
+\emph on
+instead
+\emph default
+ of
+\family typewriter
+ printf().
+
+\family default
+ For the mcs51 there additionally are assembly versions
+\family typewriter
+printf_tiny()
+\begin_inset LatexCommand \index{printf\_tiny() (mcs51)}
+
+\end_inset
+
+
+\family default
+ and
+\family typewriter
+printf_fast()
+\begin_inset LatexCommand \index{printf\_fast() (mcs51)}
+
+\end_inset
+
+
+\family default
+and
+\family typewriter
+ printf_fast_f()
+\begin_inset LatexCommand \index{printf\_fast\_f() (mcs51)}
+
+\end_inset
+
+
+\family default
+ which should fit the requirements of many embedded systems (printf_fast()
+ can be customized by unsetting #defines to
+\emph on
+not
+\emph default
+ support long variables and field widths).
+\layout Subsection
+
+Math functions (sin, pow, sqrt etc.)
+\layout Subsection
+
+Other libraries
+\layout Standard
+
+Libraries
+\begin_inset LatexCommand \index{Libraries}
+
+\end_inset
+
+ included in SDCC should have a license at least as liberal as the GNU Lesser
+ General Public License
+\begin_inset LatexCommand \index{GNU Lesser General Public License, LGPL}
+
+\end_inset
+
+
+\emph on
+LGPL
+\emph default
+.
+\layout Comment
+
+license statements for the libraries are missing.
+ sdcc/device/lib/ser_ir.c
+\layout Comment
+
+or _decdptr f.e.
+ come with a GPL (as opposed to LGPL) License - this will not be liberal
+ enough for many embedded programmers.
+\layout Standard
+
+If you have ported some library or want to share experience about some code
+ which f.e.
+ falls into any of these categories Busses (I
+\begin_inset Formula $^{\textrm{2}}$
+\end_inset
+
+C, CAN, Ethernet, Profibus, Modbus, USB, SPI, JTAG ...), Media (IDE, Memory
+ cards, eeprom, flash...), En-/Decryption, Remote debugging, Realtime kernel,
+ Keyboard, LCD, RTC, FPGA, PID then the sdcc-user mailing list
+\begin_inset LatexCommand \url{http://sourceforge.net/mail/?group_id=599}
+
+\end_inset
+
+\SpecialChar ~
+would certainly like to hear about it.
+ Programmers coding for embedded systems are not especially famous for being
+ enthusiastic, so don't expect a big hurray but as the mailing list is searchabl
+e these references are very valuable.
+ Let's help to create a climate where information is shared.
+\layout Section
+
+Memory Models
+\layout Subsection
+
+MCS51 Memory Models
+\begin_inset LatexCommand \index{Memory model}
+
+\end_inset
+
+
+\begin_inset LatexCommand \index{MCS51 memory model}
+
+\end_inset
+
+
+\layout Subsubsection
+
+Small, Medium and Large
+\layout Standard
+
+SDCC allows three memory models for MCS51 code,
+\shape slanted
+small, medium
+\shape default
+ and
+\shape slanted
+large
+\shape default
+.
+ Modules compiled with different memory models should
+\emph on
+never
+\emph default
+ be combined together or the results would be unpredictable.
+ The library routines supplied with the compiler are compiled as small,
+ medium and large.
+ The compiled library modules are contained in separate directories as small,
+ medium and large so that you can link to the appropriate set.
+\layout Standard
+
+When the medium or large model is used all variables declared without a
+ storage class will be allocated into the external ram, this includes all
+ parameters and local variables (for non-reentrant
+\begin_inset LatexCommand \index{reentrant}
+
+\end_inset
+
+ functions).
+ When the small model is used variables without storage class are allocated
+ in the internal ram.
+\layout Standard
+
+Judicious usage of the processor specific storage classes
+\begin_inset LatexCommand \index{Storage class}
+
+\end_inset
+
+ and the 'reentrant' function type will yield much more efficient code,
+ than using the large model.
+ Several optimizations are disabled when the program is compiled using the
+ large model, it is therefore recommended that the small model be used unless
+ absolutely required.
+\layout Subsubsection
+
+External Stack
+\begin_inset LatexCommand \label{sub:External-Stack}
+
+\end_inset
+
+
+\begin_inset LatexCommand \index{stack}
+
+\end_inset
+
+
+\begin_inset LatexCommand \index{External stack (mcs51)}
+
+\end_inset
+
+
+\layout Standard
+
+The external stack (-
+\begin_inset ERT
+status Collapsed
+
+\layout Standard
+
+\backslash
+/
+\end_inset
+
+-xstack option
+\begin_inset LatexCommand \index{-\/-xstack}
+
+\end_inset
+
+) is located in pdata
+\begin_inset LatexCommand \index{pdata (mcs51, ds390 storage class)}
+
+\end_inset
+
+ memory (usually at the start of the external ram segment) and uses all
+ unused space in pdata (max.
+ 256 bytes).
+ When -
+\begin_inset ERT
+status Collapsed
+
+\layout Standard
+
+\backslash
+/
+\end_inset
+
+-xstack option is used to compile the program, the parameters and local
+ variables
+\begin_inset LatexCommand \index{local variables}
+
+\end_inset
+
+ of all reentrant functions are allocated in this area.
+ This option is provided for programs with large stack space requirements.
+ When used with the -
+\begin_inset ERT
+status Collapsed
+
+\layout Standard
+
+\backslash
+/
+\end_inset
+
+-stack-auto
+\begin_inset LatexCommand \index{-\/-stack-auto}
+
+\end_inset
+
+ option, all parameters and local variables are allocated on the external
+ stack (note: support libraries will need to be recompiled with the same
+ options.
+ There is a predefined target in the library makefile).
+\layout Standard
+
+The compiler outputs the higher order address byte of the external ram segment
+ into port P2
+\begin_inset LatexCommand \index{P2 (mcs51 sfr)}
+
+\end_inset
+
+ (see also section
+\begin_inset LatexCommand \ref{sub:MCS51-variants}
+
+\end_inset
+
+), therefore when using the External Stack option, this port
+\emph on
+may not
+\emph default
+ be used by the application program.
+\layout Subsection
+
+DS390 Memory Model
+\begin_inset LatexCommand \index{Memory model}
+
+\end_inset
+
+
+\begin_inset LatexCommand \index{DS390 memory model}
+
+\end_inset
+
+
+\layout Standard
+
+The only model supported is Flat 24
+\begin_inset LatexCommand \index{Flat 24 (DS390 memory model)}
+
+\end_inset
+
+.
+ This generates code for the 24 bit contiguous addressing mode of the Dallas
+ DS80C390 part.
+ In this mode, up to four meg of external RAM or code space can be directly
+ addressed.
+ See the data sheets at www.dalsemi.com for further information on this part.
+\newline
+
+\newline
+Note that the compiler does not generate any code to place the processor
+ into 24 bitmode (although
+\emph on
+tinibios
+\emph default
+ in the ds390 libraries will do that for you).
+ If you don't use
+\emph on
+tinibios
+\emph default
+
+\begin_inset LatexCommand \index{Tinibios (DS390)}
+
+\end_inset
+
+, the boot loader or similar code must ensure that the processor is in 24
+ bit contiguous addressing mode before calling the SDCC startup code.
+\newline
+
+\newline
+Like the
+\emph on
+-
+\begin_inset ERT
+status Collapsed
+
+\layout Standard
+
+\backslash
+/
+\end_inset
+
+-model-large
+\emph default
+ option, variables will by default be placed into the XDATA segment.
+
+\newline
+
+\newline
+Segments may be placed anywhere in the 4 meg address space using the usual
+ -
+\begin_inset ERT
+status Collapsed
+
+\layout Standard
+
+\backslash
+/
+\end_inset
+
+-*-loc options.
+ Note that if any segments are located above 64K, the -r flag must be passed
+ to the linker to generate the proper segment relocations, and the Intel
+ HEX output format must be used.
+ The -r flag can be passed to the linker by using the option
+\emph on
+-Wl-r
+\emph default
+ on the SDCC command line.
+ However, currently the linker can not handle code segments > 64k.
+\layout Section
+
+Pragmas
+\begin_inset LatexCommand \index{Pragmas}
+
+\end_inset
+
+
+\layout Standard
+
+SDCC supports the following #pragma directives:
+\layout Itemize
+
+save
+\begin_inset LatexCommand \index{\#pragma save}
+
+\end_inset
+
+ - this will save all current options to the save/restore stack.
+ See #pragma\SpecialChar ~
+restore.
+\layout Itemize
+
+restore
+\begin_inset LatexCommand \index{\#pragma restore}
+
+\end_inset
+
+ - will restore saved options from the last save.
+ saves & restores can be nested.
+ SDCC uses a save/restore stack: save pushes current options to the stack,
+ restore pulls current options from the stack.
+ See #pragma\SpecialChar ~
+save.
+\newline
+
+\layout Itemize
+
+callee_saves
+\begin_inset LatexCommand \index{\#pragma callee\_saves}
+
+\end_inset
+
+
+\begin_inset LatexCommand \index{function prologue}
+
+\end_inset
+
+ function1[,function2[,function3...]] - The compiler by default uses a caller
+ saves convention for register saving across function calls, however this
+ can cause unnecessary register pushing & popping
+\begin_inset LatexCommand \index{push/pop}
+
+\end_inset
+
+ when calling small functions from larger functions.
+ This option can be used to switch off the register saving convention for
+ the function names specified.
+ The compiler will not save registers when calling these functions, extra
+ code need to be manually inserted at the entry & exit for these functions
+ to save & restore the registers used by these functions, this can SUBSTANTIALLY
+ reduce code & improve run time performance of the generated code.
+ In the future the compiler (with inter procedural analysis) may be able
+ to determine the appropriate scheme to use for each function call.
+ If -
+\begin_inset ERT
+status Collapsed
+
+\layout Standard
+
+\backslash
+/
+\end_inset
+
+-callee-saves command line option is used, the function names specified
+ in #pragma\SpecialChar ~
+callee_saves
+\begin_inset LatexCommand \index{\#pragma callee\_saves}
+
+\end_inset
+
+ is appended to the list of functions specified in the command line.
+\layout Itemize
+
+exclude
+\begin_inset LatexCommand \index{\#pragma exclude}
+
+\end_inset
+
+ none | {acc[,b[,dpl[,dph]]] - The exclude pragma disables the generation
+ of pairs of push/pop
+\begin_inset LatexCommand \index{push/pop}
+
+\end_inset
+
+ instructions in
+\emph on
+I
+\emph default
+nterrupt
+\begin_inset LatexCommand \index{interrupt}
+
+\end_inset
+
+
+\emph on
+S
+\emph default
+ervice
+\emph on
+R
+\emph default
+outines.
+ The directive should be placed immediately before the ISR function definition
+ and it affects ALL ISR functions following it.
+ To enable the normal register saving for ISR functions use #pragma\SpecialChar ~
+exclude\SpecialChar ~
+none
+\begin_inset LatexCommand \index{\#pragma exclude}
+
+\end_inset
+
+.
+ See also the related keyword _naked
+\begin_inset LatexCommand \index{\_naked}
+
+\end_inset
+
+
+\begin_inset LatexCommand \index{\_\_naked}
+
+\end_inset
+
+.
+\layout Itemize
+
+less_pedantic
+\begin_inset LatexCommand \index{\#pragma less\_pedantic}
+
+\end_inset
+
+ - the compiler will not warn you anymore for obvious mistakes, you'r on
+ your own now ;-(
+\layout Itemize
+
+disable_warning <nnnn>
+\begin_inset LatexCommand \index{\#pragma disable\_warning}
+
+\end_inset
+
+ - the compiler will not warn you anymore about warning number <nnnn>.
+\layout Itemize
+
+nogcse
+\begin_inset LatexCommand \index{\#pragma nogcse}
+
+\end_inset
+
+ - will stop global common subexpression elimination.
+\layout Itemize
+
+noinduction
+\begin_inset LatexCommand \index{\#pragma noinduction}
+
+\end_inset
+
+ - will stop loop induction optimizations.
+\layout Itemize
+
+noinvariant
+\begin_inset LatexCommand \index{\#pragma noinvariant}
+
+\end_inset
+
+ - will not do loop invariant optimizations.
+ For more details see Loop Invariants in section
+\begin_inset LatexCommand \ref{sub:Loop-Optimizations}
+
+\end_inset
+
+.
+\layout Itemize
+
+noiv
+\begin_inset LatexCommand \index{\#pragma noiv}
+
+\end_inset
+
+ - Do not generate interrupt
+\begin_inset LatexCommand \index{interrupt}
+
+\end_inset
+
+ vector table entries for all ISR functions defined after the pragma.
+ This is useful in cases where the interrupt vector table must be defined
+ manually, or when there is a secondary, manually defined interrupt vector
+ table (e.g.
+ for the autovector feature of the Cypress EZ-USB FX2).
+ More elegantly this can be achieved by obmitting the optional interrupt
+ number after the interrupt keyword, see section
+\begin_inset LatexCommand \ref{sub:Interrupt-Service-Routines}
+
+\end_inset
+
+\SpecialChar ~
+about interrupts.
+\layout Itemize
+
+nojtbound
+\begin_inset LatexCommand \index{\#pragma nojtbound}
+
+\end_inset
+
+ - will not generate code for boundary value checking, when switch statements
+ are turned into jump-tables (dangerous).
+ For more details see section
+\begin_inset LatexCommand \ref{sub:'switch'-Statements}
+
+\end_inset
+
+.
+\layout Itemize
+
+noloopreverse
+\begin_inset LatexCommand \index{\#pragma noloopreverse}
+
+\end_inset
+
+ - Will not do loop reversal optimization
+\layout Itemize
+
+nooverlay
+\begin_inset LatexCommand \index{\#pragma nooverlay}
+
+\end_inset
+
+ - the compiler will not overlay the parameters and local variables of a
+ function.
+\layout Itemize
+
+stackauto
+\begin_inset LatexCommand \index{\#pragma stackauto}
+
+\end_inset
+
+- See option -
+\begin_inset ERT
+status Collapsed
+
+\layout Standard
+
+\backslash
+/
+\end_inset
+
+-stack-auto
+\begin_inset LatexCommand \index{-\/-stack-auto}
+
+\end_inset
+
+ and section
+\begin_inset LatexCommand \ref{sec:Parameters-and-Local-Variables}
+
+\end_inset
+
+ Parameters and Local Variables.
+\layout Itemize
+
+opt_code_speed
+\begin_inset LatexCommand \index{\#pragma opt\_code\_speed}
+
+\end_inset
+
+- The compiler will optimize code generation towards fast code, possibly
+ at the expense of code size.
+\layout Itemize
+
+opt_code_size
+\begin_inset LatexCommand \index{\#pragma opt\_code\_size}
+
+\end_inset
+
+- The compiler will optimize code generation towards compact code, possibly
+ at the expense of code speed.
+\layout Itemize
+
+opt_code_balanced
+\begin_inset LatexCommand \index{\#pragma opt\_code\_balanced}
+
+\end_inset
+
+- The compiler will attempt to generate code that is both compact and fast,
+ as long as meeting one goal is not a detriment to the other (this is the
+ default).
+
+\layout Itemize
+
+std_sdcc89
+\begin_inset LatexCommand \index{\#pragma std\_sdcc89}
+
+\end_inset
+
+- Generally follow the C89 standard, but allow SDCC features that conflict
+ with the standard (default).
+\layout Itemize
+
+std_c89
+\begin_inset LatexCommand \index{\#pragma std\_c89}
+
+\end_inset
+
+- Follow the C89 standard and disable SDCC features that conflict with the
+ standard.
+\layout Itemize
+
+std_sdcc99
+\begin_inset LatexCommand \index{\#pragma std\_sdcc99}
+
+\end_inset
+
+- Generally follow the C99 standard, but allow SDCC features that conflict
+ with the standard (incomplete support).
+\layout Itemize
+
+std_c99
+\begin_inset LatexCommand \index{\#pragma std\_c99}
+
+\end_inset
+
+- Follow the C99 standard and disable SDCC features that conflict with the
+ standard (incomplete support).
+\layout Itemize
+
+codeseg <name>
+\begin_inset LatexCommand \index{\#pragma codeseg}
+
+\end_inset
+
+- Use this name (max.
+ 8 characters) for the code segment.
+\layout Itemize
+
+constseg <name>
+\begin_inset LatexCommand \index{\#pragma constseg}
+
+\end_inset
+
+- Use this name (max.
+ 8 characters) for the const segment.
+\layout Standard
+
+SDCPP supports the following #pragma directives:
+\layout Itemize
+
+preproc_asm
+\begin_inset LatexCommand \index{\#pragma preproc\_asm}
+
+\end_inset
+
+ (+ | -) - switch _asm _endasm block preprocessing on / off.
+ Default is on.
+\layout Standard
+
+The pragma's are intended to be used to turn-on or off certain optimizations
+ which might cause the compiler to generate extra stack / data space to
+ store compiler generated temporary variables.
+ This usually happens in large functions.
+ Pragma directives should be used as shown in the following example, they
+ are used to control options & optimizations for a given function; pragmas
+ should be placed before and/or after a function, placing pragma's inside
+ a function body could have unpredictable results.
+\layout Verse
+
+
+\family typewriter
+#pragma save
+\begin_inset LatexCommand \index{\#pragma save}
+
+\end_inset
+
+ \SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+/* save the current settings */
+\newline
+#pragma nogcse
+\begin_inset LatexCommand \index{\#pragma nogcse}
+
+\end_inset
+
+ \SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+/* turnoff global subexpression elimination */
+\newline
+#pragma noinduction
+\begin_inset LatexCommand \index{\#pragma noinduction}
+
+\end_inset
+
+ /* turn off induction optimizations */
+\newline
+int foo ()
+\newline
+{
+\newline
+\SpecialChar ~
+ \SpecialChar ~
+ ...
+
+\newline
+\SpecialChar ~
+ \SpecialChar ~
+ /* large code */
+\newline
+\SpecialChar ~
+ \SpecialChar ~
+ ...
+
+\newline
+}
+\newline
+#pragma restore
+\begin_inset LatexCommand \index{\#pragma restore}
+
+\end_inset
+
+ /* turn the optimizations back on */
+\layout Standard
+
+The compiler will generate a warning message when extra space is allocated.
+ It is strongly recommended that the save and restore pragma's be used when
+ changing options for a function.
+\layout Section
+
+Defines Created by the Compiler
+\layout Standard
+
+The compiler creates the following #defines
+\begin_inset LatexCommand \index{\#defines}
+
+\end_inset
+
+
+\begin_inset LatexCommand \index{Defines created by the compiler}
+
+\end_inset
+
+:
+\newline
+
+\layout Standard
+
+
+\begin_inset Tabular
+<lyxtabular version="3" rows="11" columns="2">
+<features>
+<column alignment="center" valignment="top" leftline="true" width="0">
+<column alignment="center" valignment="top" leftline="true" rightline="true" width="0">
+<row topline="true" bottomline="true">
+<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
+\begin_inset Text
+
+\layout Standard
+
+
+\series bold
+#define
+\end_inset
+</cell>
+<cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
+\begin_inset Text
+
+\layout Standard
+
+
+\series bold
+Description
+\end_inset
+</cell>
+</row>
+<row topline="true">
+<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
+\begin_inset Text
+
+\layout Standard
+
+SDCC
+\begin_inset LatexCommand \index{SDCC}
+
+\end_inset
+
+
+\end_inset
+</cell>
+<cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
+\begin_inset Text
+
+\layout Standard
+
+this Symbol is always defined
+\end_inset
+</cell>
+</row>
+<row topline="true">
+<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
+\begin_inset Text
+
+\layout Standard
+
+SDCC_mcs51
+\begin_inset LatexCommand \index{SDCC\_mcs51}
+
+\end_inset
+
+ or SDCC_ds390
+\begin_inset LatexCommand \index{SDCC\_ds390}
+
+\end_inset
+
+ or SDCC_z80
+\begin_inset LatexCommand \index{SDCC\_z80}
+
+\end_inset
+
+, etc
+\end_inset
+</cell>
+<cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
+\begin_inset Text
+
+\layout Standard
+
+depending on the model used (e.g.: -mds390
+\end_inset
+</cell>
+</row>
+<row topline="true">
+<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
+\begin_inset Text
+
+\layout Standard
+
+__mcs51
+\begin_inset LatexCommand \index{\_\_mcs51}
+
+\end_inset
+
+, __ds390
+\begin_inset LatexCommand \index{\_\_ds390}
+
+\end_inset
+
+, __hc08
+\begin_inset LatexCommand \index{\_\_hc08}
+
+\end_inset
+
+, __z80
+\begin_inset LatexCommand \index{\_\_z80}
+
+\end_inset
+
+, etc
+\end_inset
+</cell>
+<cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
+\begin_inset Text
+
+\layout Standard
+
+depending on the model used (e.g.
+ -mz80)
+\end_inset
+</cell>
+</row>
+<row topline="true">
+<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
+\begin_inset Text
+
+\layout Standard
+
+SDCC_STACK_AUTO
+\begin_inset LatexCommand \index{SDCC\_STACK\_AUTO}
+
+\end_inset
+
+
+\end_inset
+</cell>
+<cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
+\begin_inset Text
+
+\layout Standard
+
+when
+\emph on
+-
+\begin_inset ERT
+status Collapsed
+
+\layout Standard
+
+\backslash
+/
+\end_inset
+
+-stack-auto
+\emph default
+ option is used
+\end_inset
+</cell>
+</row>
+<row topline="true">
+<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
+\begin_inset Text
+
+\layout Standard
+
+SDCC_MODEL_SMALL
+\begin_inset LatexCommand \index{SDCC\_MODEL\_SMALL}
+
+\end_inset
+
+
+\end_inset
+</cell>
+<cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
+\begin_inset Text
+
+\layout Standard
+
+when
+\emph on
+-
+\begin_inset ERT
+status Collapsed
+
+\layout Standard
+
+\backslash
+/
+\end_inset
+
+-model-small
+\emph default
+ is used
+\end_inset
+</cell>
+</row>
+<row topline="true">
+<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
+\begin_inset Text
+
+\layout Standard
+
+SDCC_MODEL_MEDIUM
+\begin_inset LatexCommand \index{SDCC\_MODEL\_MEDIUM}
+
+\end_inset
+
+
+\end_inset
+</cell>
+<cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
+\begin_inset Text
+
+\layout Standard
+
+when
+\emph on
+-
+\begin_inset ERT
+status Collapsed
+
+\layout Standard
+
+\backslash
+/
+\end_inset
+
+-model-medium
+\emph default
+ is used
+\end_inset
+</cell>
+</row>
+<row topline="true">
+<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
+\begin_inset Text
+
+\layout Standard
+
+SDCC_MODEL_LARGE
+\begin_inset LatexCommand \index{SDCC\_MODEL\_LARGE}
+
+\end_inset
+
+
+\end_inset
+</cell>
+<cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
+\begin_inset Text
+
+\layout Standard
+
+when
+\emph on
+-
+\begin_inset ERT
+status Collapsed
+
+\layout Standard
+
+\backslash
+/
+\end_inset
+
+-model-large
+\emph default
+ is used
+\end_inset
+</cell>
+</row>
+<row topline="true">
+<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
+\begin_inset Text
+
+\layout Standard
+
+SDCC_USE_XSTACK
+\begin_inset LatexCommand \index{SDCC\_USE\_XSTACK}
+
+\end_inset
+
+
+\end_inset
+</cell>
+<cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
+\begin_inset Text
+
+\layout Standard
+
+when
+\emph on
+-
+\begin_inset ERT
+status Collapsed
+
+\layout Standard
+
+\backslash
+/
+\end_inset
+
+-xstack
+\emph default
+ option is used
+\end_inset
+</cell>
+</row>
+<row topline="true">
+<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
+\begin_inset Text
+
+\layout Standard
+
+SDCC_STACK_TENBIT
+\begin_inset LatexCommand \index{SDCC\_STACK\_TENBIT}
+
+\end_inset
+
+
+\end_inset
+</cell>
+<cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
+\begin_inset Text
+
+\layout Standard
+
+when
+\emph on
+-mds390
+\emph default
+ is used
+\end_inset
+</cell>
+</row>
+<row topline="true" bottomline="true">
+<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
+\begin_inset Text
+
+\layout Standard
+
+SDCC_MODEL_FLAT24
+\begin_inset LatexCommand \index{SDCC\_MODEL\_FLAT24}
+
+\end_inset
+
+
+\end_inset
+</cell>
+<cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
+\begin_inset Text
+
+\layout Standard
+
+when
+\emph on
+-mds390
+\emph default
+ is used
+\end_inset
+</cell>
+</row>
+</lyxtabular>
+
+\end_inset
+
+
+\layout Chapter
+
+Notes on supported Processors
+\layout Section
+
+MCS51 variants
+\begin_inset LatexCommand \label{sub:MCS51-variants}
+
+\end_inset
+
+
+\begin_inset LatexCommand \index{MCS51 variants}
+
+\end_inset
+
+
+\layout Standard
+
+MCS51 processors are available from many vendors and come in many different
+ flavours.
+ While they might differ considerably in respect to Special Function Registers
+ the core MCS51 is usually not modified or is kept compatible.
+
+\layout Subsection
+
+pdata access by SFR
+\layout Standard
+
+With the upcome of devices with internal xdata and flash memory devices
+ using port P2
+\begin_inset LatexCommand \index{P2 (mcs51 sfr)}
+
+\end_inset
+
+ as dedicated I/O port is becoming more popular.
+ Switching the high byte for pdata
+\begin_inset LatexCommand \index{pdata (mcs51, ds390 storage class)}
+
+\end_inset
+
+ access which was formerly done by port P2 is then achieved by a Special
+ Function Register
+\begin_inset LatexCommand \index{sfr}
+
+\end_inset
+
+.
+ In well-established MCS51 tradition the address of this
+\emph on
+sfr
+\emph default
+ is where the chip designers decided to put it.
+ Needless to say that they didn't agree on a common name either.
+ So that the startup code can correctly initialize xdata variables, you
+ should define an sfr with the name _XPAGE
+\family typewriter
+
+\begin_inset LatexCommand \index{\_XPAGE (mcs51)}
+
+\end_inset
+
+
+\family default
+ at the appropriate location if the default, port P2, is not used for this.
+ Some examples are:
+\layout Verse
+
+
+\family typewriter
+sfr at 0x92 _XPAGE; /* Cypress EZ-USB family */
+\layout Verse
+
+
+\family typewriter
+sfr at 0xaf _XPAGE; /* some Silicon Labs (Cygnal) chips */
+\layout Verse
+
+
+\family typewriter
+sfr at 0xaa _XPAGE; /* some Silicon Labs (Cygnal) chips */
+\layout Standard
+
+For more exotic implementations further customizations may be needed.
+ See section
+\begin_inset LatexCommand \ref{sub:Startup-Code}
+
+\end_inset
+
+ for other possibilities.
+\layout Subsection
+
+Other Features available by SFR
+\layout Standard
+
+Some MCS51 variants offer features like Double DPTR
+\begin_inset LatexCommand \index{DPTR}
+
+\end_inset
+
+, multiple DPTR, decrementing DPTR, 16x16 Multiply.
+ These are currently not used for the MCS51 port.
+ If you absolutely need them you can fall back to inline assembly or submit
+ a patch to SDCC.
+\layout Section
+
+DS400 port
+\layout Standard
+
+The DS80C400 microcontroller has a rich set of peripherals.
+ In its built-in ROM library it includes functions to access some of the
+ features, among them is a TCP stack with IP4 and IP6 support.
+ Library headers (currently in beta status) and other files are provided
+ at
+\size footnotesize
+
+\begin_inset LatexCommand \url{ftp://ftp.dalsemi.com/pub/tini/ds80c400/c_libraries/sdcc/index.html}
+
+\end_inset
+
+.
+
+\layout Section
+
+The Z80 and gbz80 port
+\layout Standard
+
+SDCC can target both the Zilog
+\begin_inset LatexCommand \index{Z80}
+
+\end_inset
+
+ and the Nintendo Gameboy's Z80-like gbz80
+\begin_inset LatexCommand \index{gbz80 (GameBoy Z80)}
+
+\end_inset
+
+.
+ The Z80 port is passed through the same
+\emph on
+regressions tests
+\begin_inset LatexCommand \index{Regression test}
+
+\end_inset
+
+
+\emph default
+ as the MCS51 and DS390 ports, so floating point support, support for long
+ variables and bitfield support is fine.
+ See mailing lists and forums about interrupt routines.
+\layout Standard
+
+As always, the code is the authoritative reference - see z80/ralloc.c and
+ z80/gen.c.
+ The stack
+\begin_inset LatexCommand \index{stack}
+
+\end_inset
+
+ frame is similar to that generated by the IAR Z80 compiler.
+ IX is used as the base pointer, HL and IY are used as a temporary registers,
+ and BC and DE are available for holding variables.
+ Return values
+\begin_inset LatexCommand \index{return value}
+
+\end_inset
+
+ for the Z80 port are stored in L (one byte), HL (two bytes), or DEHL (four
+ bytes).
+ The gbz80 port use the same set of registers for the return values, but
+ in a different order of significance: E (one byte), DE (two bytes), or
+ HLDE (four bytes).
+\layout Section
+
+The HC08 port
+\layout Standard
+
+The port to the Motorola HC08
+\begin_inset LatexCommand \index{HC08}
+
+\end_inset
+
+ family has been added in October 2003, and is still undergoing some basic
+ development.
+ The code generator is complete, but the register allocation is still quite
+ unoptimized.
+ Some of the SDCC's standard C library functions have embedded non-HC08
+ inline assembly and so are not yet usable.
+\newline
+
+\newline
+
+\layout Section
+
+The PIC14 port
+\layout Standard
+
+The 14bit PIC
+\begin_inset LatexCommand \index{PIC14}
+
+\end_inset
+
+ port still requires a major effort from the development community.
+ However it can work for very simple code.
+\layout Subsection
+
+C code and 14bit PIC code page
+\begin_inset LatexCommand \index{code page (pic14)}
+
+\end_inset
+
+ and RAM banks
+\begin_inset LatexCommand \index{RAM bank (pic14)}
+
+\end_inset
+
+
+\layout Standard
+
+The linker organizes allocation for the code page and RAM banks.
+ It does not have intimate knowledge of the code flow.
+ It will put all the code section of a single asm file into a single code
+ page.
+ In order to make use of multiple code pages, separate asm files must be
+ used.
+ The compiler treats all functions of a single C file as being in the same
+ code page unless it is non static.
+ The compiler treats all local variables of a single C file as being in
+ the same RAM bank unless it is an extern.
+\newline
+
+\newline
+To get the best follow these guide lines:
+\layout Enumerate
+
+make local functions static, as non static functions require code page selection
+ overhead.
+\layout Enumerate
+
+Make local variables static as extern variables require RAM bank selection
+ overhead.
+\layout Enumerate
+
+For devices that have multiple code pages it is more efficient to use the
+ same number of files as pages, i.e.
+ for the 16F877 use 4 separate files and i.e.
+ for the 16F874 use 2 separate files.
+ This way the linker can put the code for each file into different code
+ pages and the compiler can allocate reusable variables more efficiently
+ and there's less page selection overhead.
+ And as for any 8 bit micro (especially for PIC 14 as they have a very simple
+ instruction set) use 'unsigned char' whereever possible instead of 'int'.
+\layout Subsection
+
+Creating a device include file
+\layout Standard
+
+For generating a device include file use the support perl script inc2h.pl
+ kept in directory support/script.
+\layout Subsection
+
+Interrupt code
+\layout Standard
+
+For the interrupt function, use the keyword 'interrupt'
+\begin_inset LatexCommand \index{interrupt}
+
+\end_inset
+
+ with level number of 0 (PIC14 only has 1 interrupt so this number is only
+ there to avoid a syntax error - it ought to be fixed).
+ E.g.:
+\layout Verse
+
+
+\family typewriter
+void Intr(void) interrupt 0
+\newline
+{
+\newline
+\SpecialChar ~
+\SpecialChar ~
+T0IF = 0; /* Clear timer interrupt */
+\newline
+}
+\layout Subsection
+
+Linking and assembling
+\layout Standard
+
+For assembling you can use either GPUTILS'
+\begin_inset LatexCommand \index{gputils (pic tools)}
+
+\end_inset
+
+ gpasm.exe or MPLAB's mpasmwin.exe.
+ GPUTILS is available from
+\begin_inset LatexCommand \url{http://sourceforge.net/projects/gputils}
+
+\end_inset
+
+.
+ For linking you can use either GPUTIL's gplink or MPLAB's mplink.exe.
+ If you use MPLAB and an interrupt function then the linker script file
+ vectors section will need to be enlarged to link with mplink.
+\newline
+
+\newline
+Here is a
+\family typewriter
+Makefile
+\family default
+ using GPUTILS:
+\layout Verse
+
+
+\family typewriter
+.c.o:
+\newline
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+sdcc -S -V -mpic14 -p16F877 $<
+\newline
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+gpasm -c $*.asm
+\newline
+
+\newline
+$(PRJ).hex: $(OBJS)
+\newline
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+gplink -m -s $(PRJ).lkr -o $(PRJ).hex $(OBJS) libsdcc.lib
+\layout Standard
+
+Here is a
+\family typewriter
+Makefile
+\family default
+ using MPLAB:
+\layout Verse
+
+
+\family typewriter
+.c.o:
+\newline
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+sdcc -S -V -mpic14 -p16F877 $<
+\newline
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+mpasmwin /q /o $*.asm
+\newline
+
+\newline
+$(PRJ).hex: $(OBJS)
+\newline
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+mplink /v $(PRJ).lkr /m $(PRJ).map /o $(PRJ).hex $(OBJS) libsdcc.lib
+\layout Standard
+
+Please note that indentations within a
+\family typewriter
+ Makefile
+\family default
+ have to be done with a tabulator character.
+\layout Subsection
+
+Command-line options
+\layout Standard
+
+Besides the switches common to all SDCC backends, the PIC14 port accepts
+ the following options (for an updated list see sdcc -
+\begin_inset ERT
+status Collapsed
+
+\layout Standard
+
+\backslash
+/
+\end_inset
+
+-help):
+\layout List
+\labelwidthstring 00.00.0000
+
+-
+\begin_inset ERT
+status Collapsed
+
+\layout Standard
+
+\backslash
+/
+\end_inset
+
+-debug-extra emit debug info in assembly output
+\layout List
+\labelwidthstring 00.00.0000
+
+-
+\begin_inset ERT
+status Collapsed
+
+\layout Standard
+
+\backslash
+/
+\end_inset
+
+-no-pcode-opt disable (slightly faulty) optimization on pCode
+\layout Subsection
+
+The library
+\layout Subsubsection
+
+error: missing definition for symbol
+\begin_inset Quotes sld
+\end_inset
+
+__gptrget1
+\begin_inset Quotes srd
+\end_inset
+
+
+\layout Standard
+
+The PIC14 port uses library routines to provide more complex operations
+ like multiplication, division/modulus and (generic) pointer dereferencing.
+ In order to add these routines to your project, you must link with PIC14's
+
+\family typewriter
+libsdcc.lib
+\family default
+.
+ For single source file projects this is done automatically, more complex
+ projects must add
+\family typewriter
+libsdcc.lib
+\family default
+ to the linker's arguments.
+ Make sure you also add an include path for the library (using the -I switch
+ to the linker)!
+\layout Subsubsection
+
+Processor mismatch in file
+\begin_inset Quotes sld
+\end_inset
+
+XXX
+\begin_inset Quotes srd
+\end_inset
+
+.
+\layout Standard
+
+This warning can usually be ignored due to the very good compatibility amongst
+ 14 bit PIC devices.
+\layout Standard
+
+You might also consider recompiling the library for your specific device
+ by changing the ARCH=p16f877 (default target) entry in
+\family typewriter
+device/lib/pic/Makefile.in
+\family default
+ and
+\family typewriter
+device/lib/pic/Makefile
+\family default
+ to reflect your device.
+ This might even improve performance for smaller devices as unneccesary
+ BANKSELs migth be removed.
+\layout Subsection
+
+Known bugs
+\layout Subsubsection
+
+initialized data
+\layout Standard
+
+Currently, data can only be initialized if it resides in the source file
+ together with
+\emph on
+main()
+\emph default
+.
+ Data in other source files will silently
+\series bold
+not
+\series default
+ be initialized.
+\layout Section
+
+The PIC16
+\begin_inset LatexCommand \index{PIC16}
+
+\end_inset
+
+ port
+\layout Standard
+
+The PIC16
+\begin_inset LatexCommand \index{PIC16}
+
+\end_inset
+
+ port is the portion of SDCC that is responsible to produce code for the
+ Microchip
+\begin_inset LatexCommand \index{Microchip}
+
+\end_inset
+
+(TM) microcontrollers with 16 bit core.
+ Currently this family of microcontrollers contains the PIC18Fxxx and PIC18Fxxxx.
+ Currently supported devices are:
+\layout Standard
+\align center
+
+\begin_inset Tabular
+<lyxtabular version="3" rows="4" columns="6">
+<features>
+<column alignment="center" valignment="top" leftline="true" width="0">
+<column alignment="center" valignment="top" leftline="true" width="0">
+<column alignment="center" valignment="top" leftline="true" width="0">
+<column alignment="center" valignment="top" leftline="true" width="0">
+<column alignment="center" valignment="top" leftline="true" width="0">
+<column alignment="center" valignment="top" leftline="true" rightline="true" width="0">
+<row topline="true">
+<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
+\begin_inset Text
+
+\layout Standard
+
+18F242
+\end_inset
+</cell>
+<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
+\begin_inset Text
+
+\layout Standard
+
+18F248
+\end_inset
+</cell>
+<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
+\begin_inset Text
+
+\layout Standard
+
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+\end_inset
+</cell>
+<cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
+\begin_inset Text
+
+\layout Standard
+
+18F258
+\end_inset
+</cell>
+<cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
+\begin_inset Text
+
+\layout Standard
+
+18F442
+\end_inset
+</cell>
+<cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
+\begin_inset Text
+
+\layout Standard
+
+18F448
+\end_inset
+</cell>
+</row>
+<row topline="true">
+<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
+\begin_inset Text
+
+\layout Standard
+
+18F452
+\end_inset
+</cell>
+<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
+\begin_inset Text
+
+\layout Standard
+
+18F458
+\end_inset
+</cell>
+<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
+\begin_inset Text
+
+\layout Standard
+
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+\end_inset
+</cell>
+<cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
+\begin_inset Text
+
+\layout Standard
+
+18F2220
+\end_inset
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+<cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
+\begin_inset Text
+
+\layout Standard
+
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+\end_inset
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+\begin_inset Text
+
+\layout Standard
+
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+\end_inset
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+</row>
+<row topline="true">
+<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
+\begin_inset Text
+
+\layout Standard
+
+18F4455
+\end_inset
+</cell>
+<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
+\begin_inset Text
+
+\layout Standard
+
+18F6520
+\end_inset
+</cell>
+<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
+\begin_inset Text
+
+\layout Standard
+
+18F6620
+\end_inset
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+<cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
+\begin_inset Text
+
+\layout Standard
+
+18F6680
+\end_inset
+</cell>
+<cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
+\begin_inset Text
+
+\layout Standard
+
+18F6720
+\end_inset
+</cell>
+<cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
+\begin_inset Text
+
+\layout Standard
+
+18F8520
+\end_inset
+</cell>
+</row>
+<row topline="true" bottomline="true">
+<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
+\begin_inset Text
+
+\layout Standard
+
+18F8620
+\end_inset
+</cell>
+<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
+\begin_inset Text
+
+\layout Standard
+
+18F8680
+\end_inset
+</cell>
+<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
+\begin_inset Text
+
+\layout Standard
+
+18F8720
+\end_inset
+</cell>
+<cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
+\begin_inset Text
+
+\layout Standard
+
+\end_inset
+</cell>
+<cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
+\begin_inset Text
+
+\layout Standard
+
+\end_inset
+</cell>
+<cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
+\begin_inset Text
+
+\layout Standard
+
+\end_inset
+</cell>
+</row>
+</lyxtabular>
+
+\end_inset
+
+
+\layout Subsection
+
+Global Options
+\layout Standard
+
+PIC16 port supports the standard command line arguments as supposed, with
+ the exception of certain cases that will be mentioned in the following
+ list:
+\layout List
+\labelwidthstring 00.00.0000
+
+-
+\begin_inset ERT
+status Collapsed
+
+\layout Standard
+
+\backslash
+/
+\end_inset
+
+-callee-saves See -
+\begin_inset ERT
+status Collapsed
+
+\layout Standard
+
+\backslash
+/
+\end_inset
+
+-all-callee-saves
+\layout List
+\labelwidthstring 00.00.0000
+
+-
+\begin_inset ERT
+status Collapsed
+
+\layout Standard
+
+\backslash
+/
+\end_inset
+
+-all-callee-saves All function arguments are passed on stack by default.
+
+\emph on
+There is no need to specify this in the command line.
+\layout List
+\labelwidthstring 00.00.0000
+
+-
+\begin_inset ERT
+status Collapsed
+
+\layout Standard
+
+\backslash
+/
+\end_inset
+
+-fommit-frame-pointer Frame pointer will be omitted when the function uses
+ no local variables.
+\layout Subsection
+
+Port Specific Options
+\begin_inset LatexCommand \index{Options PIC16}
+
+\end_inset
+
+
+\layout Standard
+
+The port specific options appear after the global options in the sdcc --help
+ output.
+\layout Subsubsection
+
+General Options
+\layout Standard
+
+General options enable certain port features and optimizations.
+\layout List
+\labelwidthstring 00.00.0000
+
+-
+\begin_inset ERT
+status Collapsed
+
+\layout Standard
+
+\backslash
+/
+\end_inset
+
+-stack-model=[model] Used in conjuction with the command above.
+ Defines the stack model to be used, valid stack models are :
+\begin_deeper
+\layout List
+\labelwidthstring 00.00.0000
+
+
+\emph on
+small
+\emph default
+ Selects small stack model.
+ 8 bit stack and frame pointers.
+ Supports 256 bytes stack size.
+\layout List
+\labelwidthstring 00.00.0000
+
+
+\emph on
+large
+\emph default
+ Selects large stack model.
+ 16 bit stack and frame pointers.
+ Supports 65536 bytes stack size.
+\end_deeper
+\layout List
+\labelwidthstring 00.00.0000
+
+-
+\begin_inset ERT
+status Collapsed
+
+\layout Standard
+
+\backslash
+/
+\end_inset
+
+-preplace-udata-with=[kword] Replaces the default udata keyword for allocating
+ unitialized data variables with [kword].
+ Valid keywords are: "udata_acs", "udata_shr", "udata_ovr".
+\layout List
+\labelwidthstring 00.00.0000
+
+-
+\begin_inset ERT
+status Collapsed
+
+\layout Standard
+
+\backslash
+/
+\end_inset
+
+-ivt-loc <nnnn> positions the Interrupt Vector Table at location <nnnn>.
+ Useful for bootloaders.
+\layout List
+\labelwidthstring 00.00.0000
+
+-
+\begin_inset ERT
+status Collapsed
+
+\layout Standard
+
+\backslash
+/
+\end_inset
+
+-asm= sets the full path and name of an external assembler to call.
+\layout List
+\labelwidthstring 00.00.0000
+
+-
+\begin_inset ERT
+status Collapsed
+
+\layout Standard
+
+\backslash
+/
+\end_inset
+
+-link= sets the full path and name of an external linker to call.
+\layout List
+\labelwidthstring 00.00.0000
+
+-
+\begin_inset ERT
+status Collapsed
+
+\layout Standard
+
+\backslash
+/
+\end_inset
+
+-mplab-comp MPLAB compatibility option.
+ Currently only suppresses special gpasm directives.
+\layout Subsubsection
+
+Optimization Options
+\layout List
+\labelwidthstring 00.00.0000
+
+-
+\begin_inset ERT
+status Collapsed
+
+\layout Standard
+
+\backslash
+/
+\end_inset
+
+-optimize-goto Try to use (conditional) BRA instead of GOTO
+\layout List
+\labelwidthstring 00.00.0000
+
+-
+\begin_inset ERT
+status Collapsed
+
+\layout Standard
+
+\backslash
+/
+\end_inset
+
+-optimize-cmp Try to optimize some compares.
+\layout List
+\labelwidthstring 00.00.0000
+
+-
+\begin_inset ERT
+status Collapsed
+
+\layout Standard
+
+\backslash
+/
+\end_inset
+
+-optimize-df Analyze the dataflow of the generated code and improve it.
+\layout List
+\labelwidthstring 00.00.0000
+
+-
+\begin_inset ERT
+status Collapsed
+
+\layout Standard
+
+\backslash
+/
+\end_inset
+
+-obanksel=nn Set optimization level for inserting BANKSELs.
+\newline
+
+\begin_deeper
+\layout List
+\labelwidthstring 00.00.0000
+
+0 no optimization
+\layout List
+\labelwidthstring 00.00.0000
+
+1 checks previous used register and if it is the same then does not emit
+ BANKSEL, accounts only for labels.
+\layout List
+\labelwidthstring 00.00.0000
+
+2 tries to check the location of (even different) symbols and removes BANKSELs
+ if they are in the same bank.
+
+\newline
+
+\emph on
+Important: There might be problems if the linker script has data sections
+ across bank borders!
+\end_deeper
+\layout Subsubsection
+
+Linking Options
+\layout List
+\labelwidthstring 00.00.0000
+
+-
+\begin_inset ERT
+status Collapsed
+
+\layout Standard
+
+\backslash
+/
+\end_inset
+
+-nodefaultlibs do not link default libraries when linking
+\layout List
+\labelwidthstring 00.00.0000
+
+-
+\begin_inset ERT
+status Collapsed
+
+\layout Standard
+
+\backslash
+/
+\end_inset
+
+-no-crt Don't link the default run-time modules
+\layout List
+\labelwidthstring 00.00.0000
+
+-
+\begin_inset ERT
+status Collapsed
+
+\layout Standard
+
+\backslash
+/
+\end_inset
+
+-use-crt= Use a custom run-time module instead of the defaults.
+\layout Subsubsection
+
+Debugging Options
+\layout Standard
+
+Debugging options enable extra debugging information in the output files.
+\layout List
+\labelwidthstring 00.00.0000
+
+-
+\begin_inset ERT
+status Collapsed
+
+\layout Standard
+
+\backslash
+/
+\end_inset
+
+-debug-xtra Similar to -
+\begin_inset ERT
+status Collapsed
+
+\layout Standard
+
+\backslash
+/
+\end_inset
+
+-debug
+\begin_inset LatexCommand \index{-\/-debug}
+
+\end_inset
+
+, but dumps more information.
+\layout List
+\labelwidthstring 00.00.0000
+
+-
+\begin_inset ERT
+status Collapsed
+
+\layout Standard
+
+\backslash
+/
+\end_inset
+
+-debug-ralloc Force register allocator to dump <source>.d file with debugging
+ information.
+ <source> is the name of the file compiled.
+\layout List
+\labelwidthstring 00.00.0000
+
+-
+\begin_inset ERT
+status Collapsed
+
+\layout Standard
+
+\backslash
+/
+\end_inset
+
+-pcode-verbose Enable pcode debugging information in translation.
+\layout List
+\labelwidthstring 00.00.0000
+
+-
+\begin_inset ERT
+status Collapsed
+
+\layout Standard
+
+\backslash
+/
+\end_inset
+
+-denable-peeps Force the usage of peepholes.
+ Use with care.
+\layout List
+\labelwidthstring 00.00.0000
+
+-
+\begin_inset ERT
+status Collapsed
+
+\layout Standard
+
+\backslash
+/
+\end_inset
+
+-gstack Trace push/pops for stack pointer overflow
+\layout List
+\labelwidthstring 00.00.0000
+
+-
+\begin_inset ERT
+status Collapsed
+
+\layout Standard
+
+\backslash
+/
+\end_inset
+
+-call-tree dump call tree in .calltree file
+\layout Subsection
+
+Enviromental Variables
+\layout Standard
+
+There is a number of enviromental variables that can be used when running
+ SDCC to enable certain optimizations or force a specific program behaviour.
+ these variables are primarily for debugging purposes so they can be enabled/dis
+abled at will.
+\layout Standard
+
+Currently there is only two such variables available:
+\layout List
+\labelwidthstring 00.00.0000
+
+OPTIMIZE_BITFIELD_POINTER_GET when this variable exists reading of structure
+ bitfields is optimized by directly loading FSR0 with the address of the
+ bitfield structure.
+ Normally SDCC will cast the bitfield structure to a bitfield pointer and
+ then load FSR0.
+ This step saves data ram and code space for functions that perform heavy
+ use of bitfields.
+ (ie.
+ 80 bytes of code space are saved when compiling malloc.c with this option).
+
+\layout List
+\labelwidthstring 00.00.0000
+
+NO_REG_OPT do not perform pCode registers optimization.
+ This should be used for debugging purposes.
+ In some where bugs in the pcode optimizer are found, users can benefit
+ from temporarily disabling the optimizer until the bug is fixed.
+\layout Subsection
+
+Preprocessor Macros
+\layout Standard
+
+PIC16 port defines the following preprocessor macros while translating a
+ source.
+\layout Standard
+\align center
+
+\begin_inset Tabular
+<lyxtabular version="3" rows="6" columns="2">
+<features>
+<column alignment="center" valignment="top" leftline="true" width="0">
+<column alignment="center" valignment="top" leftline="true" rightline="true" width="0">
+<row topline="true" bottomline="true">
+<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
+\begin_inset Text
+
+\layout Standard
+
+Macro
+\end_inset
+</cell>
+<cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
+\begin_inset Text
+
+\layout Standard
+
+Description
+\end_inset
+</cell>
+</row>
+<row topline="true">
+<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
+\begin_inset Text
+
+\layout Standard
+
+SDCC_pic16
+\end_inset
+</cell>
+<cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
+\begin_inset Text
+
+\layout Standard
+
+Port identification
+\end_inset
+</cell>
+</row>
+<row topline="true">
+<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
+\begin_inset Text
+
+\layout Standard
+
+_
+\begin_inset ERT
+status Collapsed
+
+\layout Standard
+
+\backslash
+/
+\end_inset
+
+_pic16
+\end_inset
+</cell>
+<cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
+\begin_inset Text
+
+\layout Standard
+
+Port identification (same as above)
+\end_inset
+</cell>
+</row>
+<row topline="true">
+<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
+\begin_inset Text
+
+\layout Standard
+
+pic18fxxxx
+\end_inset
+</cell>
+<cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
+\begin_inset Text
+
+\layout Standard
+
+MCU Identification.
+
+\emph on
+xxxx
+\emph default
+ is the microcontrol identification number, i.e.
+ 452, 6620, etc
+\end_inset
+</cell>
+</row>
+<row topline="true">
+<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
+\begin_inset Text
+
+\layout Standard
+
+_
+\begin_inset ERT
+status Collapsed
+
+\layout Standard
+
+\backslash
+/
+\end_inset
+
+_18Fxxxx
+\end_inset
+</cell>
+<cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
+\begin_inset Text
+
+\layout Standard
+
+MCU Identification (same as above)
+\end_inset
+</cell>
+</row>
+<row topline="true" bottomline="true">
+<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
+\begin_inset Text
+
+\layout Standard
+
+STACK_MODEL_nnn
+\end_inset
+</cell>
+<cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
+\begin_inset Text
+
+\layout Standard
+
+nnn = SMALL or LARGE respectively according to the stack model used
+\end_inset
+</cell>
+</row>
+</lyxtabular>
+
+\end_inset
+
+
+\layout Standard
+
+In addition the following macros are defined when calling assembler:
+\layout Standard
+\align center
+
+\begin_inset Tabular
+<lyxtabular version="3" rows="4" columns="2">
+<features>
+<column alignment="center" valignment="top" leftline="true" width="0">
+<column alignment="center" valignment="top" leftline="true" rightline="true" width="0">
+<row topline="true" bottomline="true">
+<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
+\begin_inset Text
+
+\layout Standard
+
+Macro
+\end_inset
+</cell>
+<cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
+\begin_inset Text
+
+\layout Standard
+
+Description
+\end_inset
+</cell>
+</row>
+<row topline="true">
+<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
+\begin_inset Text
+
+\layout Standard
+
+__18Fxxxx
+\end_inset
+</cell>
+<cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
+\begin_inset Text
+
+\layout Standard
+
+MCU Identification.
+
+\emph on
+xxxx
+\emph default
+ is the microcontrol identification number, i.e.
+ 452, 6620, etc
+\end_inset
+</cell>
+</row>
+<row topline="true">
+<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
+\begin_inset Text
+
+\layout Standard
+
+SDCC_MODEL_nnn
+\end_inset
+</cell>
+<cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
+\begin_inset Text
+
+\layout Standard
+
+nnn = SMALL or LARGE respectively according to the memory model used for
+ SDCC
+\end_inset
+</cell>
+</row>
+<row topline="true" bottomline="true">
+<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
+\begin_inset Text
+
+\layout Standard
+
+STACK_MODEL_nnn
+\end_inset
+</cell>
+<cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
+\begin_inset Text
+
+\layout Standard
+
+nnn = SMALL or LARGE respectively according to the stack model used
+\end_inset
+</cell>
+</row>
+</lyxtabular>
+
+\end_inset
+
+
+\layout Subsection
+
+Directories
+\layout Standard
+
+PIC16
+\begin_inset LatexCommand \index{PIC16}
+
+\end_inset
+
+ port uses the following directories for searching header files and libraries.
+\layout Standard
+\align center
+
+\begin_inset Tabular
+<lyxtabular version="3" rows="3" columns="4">
+<features>
+<column alignment="center" valignment="top" leftline="true" width="0">
+<column alignment="center" valignment="top" leftline="true" rightline="true" width="0">
+<column alignment="center" valignment="top" width="0">
+<column alignment="center" valignment="top" leftline="true" rightline="true" width="0">
+<row topline="true" bottomline="true">
+<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
+\begin_inset Text
+
+\layout Standard
+
+Directory
+\end_inset
+</cell>
+<cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
+\begin_inset Text
+
+\layout Standard
+
+Description
+\end_inset
+</cell>
+<cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
+\begin_inset Text
+
+\layout Standard
+
+Target
+\end_inset
+</cell>
+<cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
+\begin_inset Text
+
+\layout Standard
+
+Command prefix
+\end_inset
+</cell>
+</row>
+<row topline="true">
+<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
+\begin_inset Text
+
+\layout Standard
+
+PREFIX/sdcc/include/pic16
+\end_inset
+</cell>
+<cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
+\begin_inset Text
+
+\layout Standard
+
+PIC16 specific headers
+\end_inset
+</cell>
+<cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
+\begin_inset Text
+
+\layout Standard
+
+Compiler
+\end_inset
+</cell>
+<cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
+\begin_inset Text
+
+\layout Standard
+
+-I
+\end_inset
+</cell>
+</row>
+<row topline="true" bottomline="true">
+<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
+\begin_inset Text
+
+\layout Standard
+
+PREFIX/sdcc/lib/pic16
+\end_inset
+</cell>
+<cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
+\begin_inset Text
+
+\layout Standard
+
+PIC16 specific libraries
+\end_inset
+</cell>
+<cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
+\begin_inset Text
+
+\layout Standard
+
+Linker
+\end_inset
+</cell>
+<cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
+\begin_inset Text
+
+\layout Standard
+
+-L
+\end_inset
+</cell>
+</row>
+</lyxtabular>
+
+\end_inset
+
+
+\layout Subsection
+
+Pragmas
+\begin_inset LatexCommand \label{sub:PIC16_Pragmas}
+
+\end_inset
+
+
+\layout Standard
+
+PIC16 port currently supports the following pragmas:
+\layout List
+\labelwidthstring 00.00.0000
+
+stack pragma stack forces the code generator to initialize the stack & frame
+ pointers at a specific address.
+ This is an adhoc solution for cases where no STACK directive is available
+ in the linker script or gplink is not instructed to create a stack section.
+\newline
+The stack pragma should be used only once in a project.
+ Multiple pragmas may result in indeterminate behaviour of the program.
+\begin_inset Foot
+collapsed false
+
+\layout Standard
+
+The old format (ie.
+ #pragma stack 0x5ff) is deprecated and will cause the stack pointer to
+ cross page boundaries (or even exceed the available data RAM) and crash
+ the program.
+ Make sure that stack does not cross page boundaries when using the SMALL
+ stack model.
+\end_inset
+
+
+\newline
+The format is as follows:
+\layout LyX-Code
+
+#pragma stack bottom_address [stack_size]
+\layout Standard
+
+
+\emph on
+bottom_address
+\emph default
+ is the lower bound of the stack section.
+ The stack pointer initially will point at address (bottom_address+stack_size-1).
+\layout LyX-Code
+
+Example:
+\layout LyX-Code
+
+\layout LyX-Code
+
+/* initializes stack of 100 bytes at RAM address 0x200 */
+\layout LyX-Code
+
+#pragma stack 0x200 100
+\layout Standard
+
+If the stack_size field is omitted then a stack is created with the default
+ size of 64.
+ This size might be enough for most programs, but its not enough for operations
+ with deep function nesting or excessive stack usage.
+\layout List
+\labelwidthstring 00.00.0000
+
+wparam
+\emph on
+This pragma is deprecated.
+ Its use will cause a warning message to be issued.
+\emph default
+
+\newline
+
+\layout List
+\labelwidthstring 00.00.0000
+
+code place a function symbol at static FLASH address
+\layout LyX-Code
+
+Example:
+\layout LyX-Code
+
+\layout LyX-Code
+
+/* place function test_func at 0x4000 */
+\layout LyX-Code
+
+#pragma code test_func 0x4000
+\layout LyX-Code
+
+\layout List
+\labelwidthstring 00.00.0000
+
+library instructs the linker to use a library module.
+\newline
+Usage:
+\layout LyX-Code
+
+#pragma library module_name
+\layout Standard
+
+
+\emph on
+module_name
+\emph default
+ can be any library or object file (including its path).
+ Note that there are four reserved keywords which have special meaning.
+ These are:
+\layout Standard
+\align center
+
+\begin_inset Tabular
+<lyxtabular version="3" rows="6" columns="3">
+<features>
+<column alignment="center" valignment="top" leftline="true" width="0">
+<column alignment="block" valignment="top" leftline="true" width="20page%">
+<column alignment="left" valignment="top" leftline="true" rightline="true" width="0">
+<row topline="true" bottomline="true">
+<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
+\begin_inset Text
+
+\layout Standard
+
+Keyword
+\end_inset
+</cell>
+<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
+\begin_inset Text
+
+\layout Standard
+
+Description
+\end_inset
+</cell>
+<cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
+\begin_inset Text
+
+\layout Standard
+
+Module to link
+\end_inset
+</cell>
+</row>
+<row topline="true">
+<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
+\begin_inset Text
+
+\layout Standard
+
+
+\series bold
+ignore
+\end_inset
+</cell>
+<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
+\begin_inset Text
+
+\layout Standard
+
+ignore all library pragmas
+\end_inset
+</cell>
+<cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
+\begin_inset Text
+
+\layout Standard
+
+
+\emph on
+(none)
+\end_inset
+</cell>
+</row>
+<row topline="true">
+<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
+\begin_inset Text
+
+\layout Standard
+
+
+\series bold
+c
+\end_inset
+</cell>
+<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
+\begin_inset Text
+
+\layout Standard
+
+link the C library
+\end_inset
+</cell>
+<cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
+\begin_inset Text
+
+\layout Standard
+
+
+\emph on
+libc18f
+\emph default
+.lib
+\end_inset
+</cell>
+</row>
+<row topline="true">
+<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
+\begin_inset Text
+
+\layout Standard
+
+
+\series bold
+math
+\end_inset
+</cell>
+<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
+\begin_inset Text
+
+\layout Standard
+
+link the Math libarary
+\end_inset
+</cell>
+<cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
+\begin_inset Text
+
+\layout Standard
+
+
+\emph on
+libm18f
+\emph default
+.lib
+\end_inset
+</cell>
+</row>
+<row topline="true">
+<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
+\begin_inset Text
+
+\layout Standard
+
+
+\series bold
+io
+\end_inset
+</cell>
+<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
+\begin_inset Text
+
+\layout Standard
+
+link the I/O library
+\end_inset
+</cell>
+<cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
+\begin_inset Text
+
+\layout Standard
+
+
+\emph on
+libio18f*
+\emph default
+.lib
+\end_inset
+</cell>
+</row>
+<row topline="true" bottomline="true">
+<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
+\begin_inset Text
+
+\layout Standard
+
+
+\series bold
+debug
+\end_inset
+</cell>
+<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
+\begin_inset Text
+
+\layout Standard
+
+link the debug library
+\end_inset
+</cell>
+<cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
+\begin_inset Text
+
+\layout Standard
+
+
+\emph on
+libdebug
+\emph default
+.lib
+\end_inset
+</cell>
+</row>
+</lyxtabular>
+
+\end_inset
+
+
+\newline
+* is the device number, i.e.
+ 452 for PIC18F452 MCU.
+\layout Standard
+
+This feature allows for linking with specific libraries withoug having to
+ explicit name them in the command line.
+ Note that the
+\noun on
+ignore
+\noun default
+ keyword will reject all modules specified by the library pragma.
+\layout List
+\labelwidthstring 00.00.0000
+
+udata pragma udata instructs the compiler to emit code so that linker will
+ place a variable at a specific memory bank
+\layout LyX-Code
+
+Example:
+\layout LyX-Code
+
+\layout LyX-Code
+
+/* places variable foo at bank2 */
+\layout LyX-Code
+
+#pragma udata bank2 foo
+\layout LyX-Code
+
+char foo;
+\layout Standard
+
+In order for this pragma to work extra SECTION directives should be added
+ in the .lkr script.
+ In the following example a sample .lkr file is shown:
+\layout LyX-Code
+
+\layout LyX-Code
+
+// Sample linker script for the PIC18F452 processor
+\layout LyX-Code
+
+LIBPATH .
+\layout LyX-Code
+
+CODEPAGE NAME=vectors START=0x0 END=0x29 PROTECTED
+\layout LyX-Code
+
+CODEPAGE NAME=page START=0x2A END=0x7FFF
+\layout LyX-Code
+
+CODEPAGE NAME=idlocs START=0x200000 END=0x200007 PROTECTED
+\layout LyX-Code
+
+CODEPAGE NAME=config START=0x300000 END=0x30000D PROTECTED
+\layout LyX-Code
+
+CODEPAGE NAME=devid START=0x3FFFFE END=0x3FFFFF PROTECTED
+\layout LyX-Code
+
+CODEPAGE NAME=eedata START=0xF00000 END=0xF000FF PROTECTED
+\layout LyX-Code
+
+ACCESSBANK NAME=accessram START=0x0 END=0x7F
+\layout LyX-Code
+
+\layout LyX-Code
+
+DATABANK NAME=gpr0 START=0x80 END=0xFF
+\layout LyX-Code
+
+DATABANK NAME=gpr1 START=0x100 END=0x1FF
+\layout LyX-Code
+
+DATABANK NAME=gpr2 START=0x200 END=0x2FF
+\layout LyX-Code
+
+DATABANK NAME=gpr3 START=0x300 END=0x3FF
+\layout LyX-Code
+
+DATABANK NAME=gpr4 START=0x400 END=0x4FF
+\layout LyX-Code
+
+DATABANK NAME=gpr5 START=0x500 END=0x5FF
+\layout LyX-Code
+
+ACCESSBANK NAME=accesssfr START=0xF80 END=0xFFF PROTECTED
+\layout LyX-Code
+
+\layout LyX-Code
+
+SECTION NAME=CONFIG ROM=config
+\layout LyX-Code
+
+\layout LyX-Code
+
+SECTION NAME=bank0 RAM=gpr0 # these SECTION directives
+\layout LyX-Code
+
+SECTION NAME=bank1 RAM=gpr1 # should be added to link
+\layout LyX-Code
+
+SECTION NAME=bank2 RAM=gpr2 # section name 'bank?' with
+\layout LyX-Code
+
+SECTION NAME=bank3 RAM=gpr3 # a specific DATABANK name
+\layout LyX-Code
+
+SECTION NAME=bank4 RAM=gpr4
+\layout LyX-Code
+
+SECTION NAME=bank5 RAM=gpr5
+\layout Standard
+
+The linker will recognise the section name set in the pragma statement and
+ will position the variable at the memory bank set with the RAM field at
+ the SECTION line in the linker script file.
+\layout Subsection
+
+Header Files
+\begin_inset LatexCommand \label{sub:PIC16_Header-Files}
+
+\end_inset
+
+
+\layout Standard
+
+There is one main header file that can be included to the source files using
+ the pic16 port.
+ That file is the
+\series bold
+pic18fregs.h
+\series default
+.
+ This header file contains the definitions for the processor special registers,
+ so it is necessary if the source accesses them.
+ It can be included by adding the following line in the beginning of the
+ file:
+\layout LyX-Code
+
+#include <pic18fregs.h>
+\layout Standard
+
+The specific microcontroller is selected within the pic18fregs.h automatically,
+ so the same source can be used with a variety of devices.
+\layout Subsection
+
+Libraries
+\layout Standard
+
+The libraries that PIC16
+\begin_inset LatexCommand \index{PIC16}
+
+\end_inset
+
+ port depends on are the microcontroller device libraries which contain
+ the symbol definitions for the microcontroller special function registers.
+ These libraries have the format pic18fxxxx.lib, where
+\emph on
+xxxx
+\emph default
+ is the microcontroller identification number.
+ The specific library is selected automatically by the compiler at link
+ stage according to the selected device.
+\layout Standard
+
+Libraries are created with gplib which is part of the gputils package
+\begin_inset LatexCommand \url{http://sourceforge.net/projects/gputils}
+
+\end_inset
+
+.
+\layout Subsubsection*
+
+Building the libraries
+\layout Standard
+
+Before using SDCC/pic16 there are some libraries that need to be compiled.
+ This process is not done automatically by SDCC since not all users use
+ SDCC for pic16 projects.
+ So each user should compile the libraries separately.
+\layout Standard
+
+The steps to compile the pic16 libraries under Linux are:
+\layout LyX-Code
+
+cd device/lib/pic16
+\layout LyX-Code
+
+./configure
+\layout LyX-Code
+
+make
+\layout LyX-Code
+
+cd ..
+\layout LyX-Code
+
+make model-pic16
+\layout LyX-Code
+
+su -c 'make install' # install the libraries, you need the root password
+\layout Standard
+
+If you need to install the headers too, do:
+\layout LyX-Code
+
+cd device/include
+\layout LyX-Code
+
+su -c 'make install' # install the headers, you need the root password
+\layout Standard
+
+There exist a special target to build the I/O libraries.
+ This target is not automatically build because it will build the I/O library
+ for
+\emph on
+every
+\emph default
+ supported device.
+ This way building will take quite a lot of time.
+ Users are advised to edit the
+\series bold
+device/lib/pic16/pics.build
+\series default
+ file and then execute:
+\layout LyX-Code
+
+make lib-io
+\layout Subsection
+
+Memory Models
+\layout Standard
+
+The following memory models are supported by the PIC16 port:
+\layout Itemize
+
+small model
+\layout Itemize
+
+large model
+\layout Standard
+
+Memory model affects the default size of pointers within the source.
+ The sizes are shown in the next table:
+\layout Standard
+\align center
+
+\begin_inset Tabular
+<lyxtabular version="3" rows="3" columns="3">
+<features>
+<column alignment="center" valignment="top" leftline="true" rightline="true" width="0">
+<column alignment="center" valignment="top" leftline="true" width="0">
+<column alignment="center" valignment="top" leftline="true" rightline="true" width="0">
+<row topline="true" bottomline="true">
+<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
+\begin_inset Text
+
+\layout Standard
+
+Pointer sizes according to memory model
+\end_inset
+</cell>
+<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
+\begin_inset Text
+
+\layout Standard
+
+small model
+\end_inset
+</cell>
+<cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
+\begin_inset Text
+
+\layout Standard
+
+large model
+\end_inset
+</cell>
+</row>
+<row topline="true" bottomline="true">
+<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
+\begin_inset Text
+
+\layout Standard
+
+code pointers
+\end_inset
+</cell>
+<cell multicolumn="1" alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
+\begin_inset Text
+
+\layout Standard
+
+16-bits
+\end_inset
+</cell>
+<cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
+\begin_inset Text
+
+\layout Standard
+
+24-bits
+\end_inset
+</cell>
+</row>
+<row topline="true" bottomline="true">
+<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
+\begin_inset Text
+
+\layout Standard
+
+data pointers
+\end_inset
+</cell>
+<cell multicolumn="1" alignment="center" valignment="top" topline="true" bottomline="true" leftline="true" usebox="none">
+\begin_inset Text
+
+\layout Standard
+
+16-bits
+\end_inset
+</cell>
+<cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
+\begin_inset Text
+
+\layout Standard
+
+16-bits
+\end_inset
+</cell>
+</row>
+</lyxtabular>
+
+\end_inset
+
+
+\layout Standard
+
+It is advisable that all sources within a project are compiled with the
+ same memory model.
+ If one wants to override the default memory model, this can be done by
+ declaring a pointer as
+\series bold
+far
+\series default
+ or
+\series bold
+near
+\series default
+.
+ Far selects large memory model's pointers, while near selects small memory
+ model's pointers.
+\layout Standard
+
+The standard device libraries (see
+\begin_inset LatexCommand \ref{sub:PIC16_Header-Files}
+
+\end_inset
+
+) contain no reference to pointers, so they can be used with both memory
+ models.
+\layout Subsection
+
+Stack
+\layout Standard
+
+The stack implementation for the PIC16 port uses two indirect registers,
+ FSR1 and FSR2.
+\layout List
+\labelwidthstring 00.00.0000
+
+FSR1 is assigned as stack pointer
+\layout List
+\labelwidthstring 00.00.0000
+
+FSR2 is assigned as frame pointer
+\layout Standard
+
+The following stack models are supported by the PIC16 port
+\layout Itemize
+
+
+\noun on
+small
+\noun default
+ model
+\layout Itemize
+
+
+\noun on
+large
+\noun default
+ model
+\layout Standard
+
+
+\noun on
+Small
+\noun default
+ model means that only the FSRxL byte is used to access stack and frame,
+ while
+\emph on
+\noun on
+large
+\emph default
+\noun default
+ uses both FSRxL and FSRxH registers.
+ The following table shows the stack/frame pointers sizes according to stack
+ model and the maximum space they can address:
+\layout Standard
+\align center
+
+\begin_inset Tabular
+<lyxtabular version="3" rows="3" columns="3">
+<features>
+<column alignment="center" valignment="top" leftline="true" rightline="true" width="0">
+<column alignment="center" valignment="top" leftline="true" width="0">
+<column alignment="center" valignment="top" leftline="true" rightline="true" width="0">
+<row topline="true" bottomline="true">
+<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
+\begin_inset Text
+
+\layout Standard
+
+Stack & Frame pointer sizes according to stack model
+\end_inset
+</cell>
+<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
+\begin_inset Text
+
+\layout Standard
+
+small
+\end_inset
+</cell>
+<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
+\begin_inset Text
+
+\layout Standard
+
+large
+\end_inset
+</cell>
+</row>
+<row topline="true">
+<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
+\begin_inset Text
+
+\layout Standard
+
+Stack pointer FSR1
+\end_inset
+</cell>
+<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
+\begin_inset Text
+
+\layout Standard
+
+8-bits
+\end_inset
+</cell>
+<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
+\begin_inset Text
+
+\layout Standard
+
+16-bits
+\end_inset
+</cell>
+</row>
+<row topline="true" bottomline="true">
+<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
+\begin_inset Text
+
+\layout Standard
+
+Frame pointer FSR2
+\end_inset
+</cell>
+<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
+\begin_inset Text
+
+\layout Standard
+
+8-bits
+\end_inset
+</cell>
+<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
+\begin_inset Text
+
+\layout Standard
+
+16-bits
+\end_inset
+</cell>
+</row>
+</lyxtabular>
+
+\end_inset
+
+
+\layout Standard
+
+
+\noun on
+Large
+\noun default
+stack model is currently not working properly throughout the code generator.
+ So its use is not advised.
+ Also there are some other points that need special care:
+\newline
+
+\layout Enumerate
+
+Do not create stack sections with size more than one physical bank (that
+ is 256 bytes)
+\layout Enumerate
+
+Stack sections should no cross physical bank limits (i.e.
+ #pragma stack 0x50 0x100)
+\layout Standard
+
+These limitations are caused by the fact that only FSRxL is modified when
+ using SMALL stack model, so no more than 256 bytes of stack can be used.
+ This problem will disappear after LARGE model is fully implemented.
+\layout Subsection
+
+Functions
+\layout Standard
+
+In addition to the standard SDCC function keywords, PIC16 port makes available
+ two more:
+\layout List
+\labelwidthstring 00.00.0000
+
+wparam Use the WREG to pass one byte of the first function argument.
+ This improves speed but you may not use this for functions with arguments
+ that are called via function pointers, otherwise the first byte of the
+ first parameter will get lost.
+ Usage:
+\layout LyX-Code
+
+void func_wparam(int a) wparam
+\layout LyX-Code
+
+{
+\layout LyX-Code
+
+ /* WREG hold the lower part of a */
+\layout LyX-Code
+
+ /* the high part of a is stored in FSR2+2 (or +3 for large stack model)
+ */
+\layout LyX-Code
+
+...
+\layout LyX-Code
+
+}
+\layout Standard
+
+This keyword replaces the deprecated wparam pragma.
+\layout List
+\labelwidthstring 00.00.0000
+
+shadowregs When entering/exiting an ISR, it is possible to take advantage
+ of the PIC18F hardware shadow registers which hold the values of WREG,
+ STATUS and BSR registers.
+ This can be done by adding the keyword
+\emph on
+shadowregs
+\emph default
+ before the
+\emph on
+interrupt
+\emph default
+ keyword in the function's header.
+\layout LyX-Code
+
+void isr_shadow(void) shadowregs interrupt 1
+\layout LyX-Code
+
+{
+\layout LyX-Code
+
+...
+\layout LyX-Code
+
+}
+\layout Standard
+
+
+\emph on
+shadowregs
+\emph default
+ instructs the code generator not to store/restore WREG, STATUS, BSR when
+ entering/exiting the ISR.
+\layout Subsection
+
+Function return values
+\layout Standard
+
+Return values from functions are placed to the appropriate registers following
+ a modified Microchip policy optimized for SDCC.
+ The following table shows these registers:
+\layout Standard
+\align center
+
+\begin_inset Tabular
+<lyxtabular version="3" rows="6" columns="2">
+<features>
+<column alignment="center" valignment="top" leftline="true" width="0">
+<column alignment="center" valignment="top" leftline="true" rightline="true" width="0">
+<row topline="true" bottomline="true">
+<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
+\begin_inset Text
+
+\layout Standard
+
+size
+\end_inset
+</cell>
+<cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
+\begin_inset Text
+
+\layout Standard
+
+destination register
+\end_inset
+</cell>
+</row>
+<row topline="true">
+<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
+\begin_inset Text
+
+\layout Standard
+
+8 bits
+\end_inset
+</cell>
+<cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
+\begin_inset Text
+
+\layout Standard
+
+WREG
+\end_inset
+</cell>
+</row>
+<row topline="true">
+<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
+\begin_inset Text
+
+\layout Standard
+
+16 bits
+\end_inset
+</cell>
+<cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
+\begin_inset Text
+
+\layout Standard
+
+PRODL:WREG
+\end_inset
+</cell>
+</row>
+<row topline="true">
+<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
+\begin_inset Text
+
+\layout Standard
+
+24 bits
+\end_inset
+</cell>
+<cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
+\begin_inset Text
+
+\layout Standard
+
+PRODH:PRODL:WREG
+\end_inset
+</cell>
+</row>
+<row topline="true">
+<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
+\begin_inset Text
+
+\layout Standard
+
+32 bits
+\end_inset
+</cell>
+<cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
+\begin_inset Text
+
+\layout Standard
+
+FSR0L:PRODH:PRODL:WREG
+\end_inset
+</cell>
+</row>
+<row topline="true" bottomline="true">
+<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
+\begin_inset Text
+
+\layout Standard
+
+>32 bits
+\end_inset
+</cell>
+<cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
+\begin_inset Text
+
+\layout Standard
+
+on stack, FSR0 points to the beginning
+\end_inset
+</cell>
+</row>
+</lyxtabular>
+
+\end_inset
+
+
+\layout Subsection
+
+Interrupts
+\layout Standard
+
+An interrupt servive routine (ISR) is declared using the
+\emph on
+interrupt
+\emph default
+ keyword.
+\layout LyX-Code
+
+void isr(void) interrupt
+\emph on
+n
+\layout LyX-Code
+
+{
+\layout LyX-Code
+
+...
+\layout LyX-Code
+
+}
+\layout Standard
+
+
+\emph on
+n
+\emph default
+ is the interrupt number, which for PIC18F devices can be:
+\layout Standard
+\align center
+
+\begin_inset Tabular
+<lyxtabular version="3" rows="4" columns="3">
+<features>
+<column alignment="center" valignment="top" leftline="true" width="0">
+<column alignment="center" valignment="top" leftline="true" width="0">
+<column alignment="center" valignment="top" leftline="true" rightline="true" width="0">
+<row topline="true" bottomline="true">
+<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
+\begin_inset Text
+
+\layout Standard
+
+
+\emph on
+n
+\end_inset
+</cell>
+<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
+\begin_inset Text
+
+\layout Standard
+
+Interrupt Vector
+\end_inset
+</cell>
+<cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
+\begin_inset Text
+
+\layout Standard
+
+Interrupt Vector Address
+\end_inset
+</cell>
+</row>
+<row topline="true">
+<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
+\begin_inset Text
+
+\layout Standard
+
+0
+\end_inset
+</cell>
+<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
+\begin_inset Text
+
+\layout Standard
+
+RESET vector
+\end_inset
+</cell>
+<cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
+\begin_inset Text
+
+\layout Standard
+
+0x000000
+\end_inset
+</cell>
+</row>
+<row topline="true">
+<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
+\begin_inset Text
+
+\layout Standard
+
+
+\family roman
+\series medium
+\shape up
+\size normal
+\emph off
+\bar no
+\noun off
+\color none
+1
+\end_inset
+</cell>
+<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
+\begin_inset Text
+
+\layout Standard
+
+
+\family roman
+\series medium
+\shape up
+\size normal
+\emph off
+\bar no
+\noun off
+\color none
+HIGH priority interrupts
+\end_inset
+</cell>
+<cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
+\begin_inset Text
+
+\layout Standard
+
+0x000008
+\end_inset
+</cell>
+</row>
+<row topline="true" bottomline="true">
+<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
+\begin_inset Text
+
+\layout Standard
+
+2
+\end_inset
+</cell>
+<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
+\begin_inset Text
+
+\layout Standard
+
+LOW priority interrupts
+\end_inset
+</cell>
+<cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
+\begin_inset Text
+
+\layout Standard
+
+0x000018
+\end_inset
+</cell>
+</row>
+</lyxtabular>
+
+\end_inset
+
+
+\layout Standard
+
+When generating assembly code for ISR the code generator places a
+\noun on
+goto
+\noun default
+instruction at the
+\emph on
+Interrupt Vector Address
+\emph default
+ which points at the genetated ISR.
+ This single GOTO instruction is part of an automatically generated
+\emph on
+interrupt entry point
+\emph default
+ function.
+ The actuall ISR code is placed as normally would in the code space.
+ Upon interrupt request, the GOTO instruction is executed which jumps to
+ the ISR code.
+ When declaring interrupt functions as _naked this GOTO instruction is
+\series bold
+not
+\series default
+ generated.
+ The whole interrupt functions is therefore placed at the Interrupt Vector
+ Address of the specific interrupt.
+ This is not a problem for the LOW priority interrupts, but it is a problem
+ for the RESET and the HIGH priority interrupts because code may be written
+ at the next interrupt´s vector address and cause undeterminate program
+ behaviour if that interrupt is raised.
+\begin_inset Foot
+collapsed false
+
+\layout Standard
+
+This is not a problem when
+\layout Enumerate
+
+this is a HIGH interrupt ISR and LOW interrupts are
+\emph on
+disabled
+\emph default
+ or not used.
+\layout Enumerate
+
+when the ISR is small enough not to reach the next interrupt´s vector address.
+\end_inset
+
+
+\layout Standard
+
+
+\emph on
+n
+\emph default
+ is possible to be omitted.
+ This way a function is generated similar to an ISR, but it is not assigned
+ to any interrupt.
+\layout Standard
+
+When entering an interrupt, currently the PIC16
+\begin_inset LatexCommand \index{PIC16}
+
+\end_inset
+
+ port automatically saves the following registers:
+\layout Itemize
+
+WREG
+\layout Itemize
+
+STATUS
+\layout Itemize
+
+BSR
+\layout Itemize
+
+PROD (PRODL and PRODH)
+\layout Itemize
+
+FSR0 (FSR0L and FSR0H)
+\layout Standard
+
+These registers are restored upon return from the interrupt routine.
+\begin_inset Foot
+collapsed false
+
+\layout Standard
+
+NOTE that when the _naked attribute is specified for an interrupt routine,
+ then NO registers are stored or restored.
+\end_inset
+
+
+\layout Subsection
+
+Generic Pointers
+\layout Standard
+
+Generic pointers are implemented in PIC16 port as 3-byte (24-bit) types.
+ There are 3 types of generic pointers currently implemented data, code
+ and eeprom pointers.
+ They are differentiated by the value of the 7th and 6th bits of the upper
+ byte:
+\layout Standard
+\align center
+
+\begin_inset Tabular
+<lyxtabular version="3" rows="5" columns="5">
+<features>
+<column alignment="center" valignment="top" leftline="true" rightline="true" width="0">
+<column alignment="center" valignment="top" width="0">
+<column alignment="center" valignment="top" leftline="true" rightline="true" width="0">
+<column alignment="center" valignment="top" width="0">
+<column alignment="left" valignment="top" rightline="true" width="0">
+<row topline="true" bottomline="true">
+<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
+\begin_inset Text
+
+\layout Standard
+
+pointer type
+\end_inset
+</cell>
+<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
+\begin_inset Text
+
+\layout Standard
+
+7th bit
+\end_inset
+</cell>
+<cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
+\begin_inset Text
+
+\layout Standard
+
+6th bit
+\end_inset
+</cell>
+<cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
+\begin_inset Text
+
+\layout Standard
+
+rest of the pointer
+\end_inset
+</cell>
+<cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
+\begin_inset Text
+
+\layout Standard
+
+descrption
+\end_inset
+</cell>
+</row>
+<row topline="true" bottomline="true">
+<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
+\begin_inset Text
+
+\layout Standard
+
+data
+\end_inset
+</cell>
+<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
+\begin_inset Text
+
+\layout Standard
+
+1
+\end_inset
+</cell>
+<cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
+\begin_inset Text
+
+\layout Standard
+
+0
+\end_inset
+</cell>
+<cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
+\begin_inset Text
+
+\layout Standard
+
+
+\family typewriter
+\shape slanted
+\emph on
+uuuuuu uuuuxxxx xxxxxxxx
+\end_inset
+</cell>
+<cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
+\begin_inset Text
+
+\layout Standard
+
+a 12-bit data pointer in data RAM memory
+\end_inset
+</cell>
+</row>
+<row bottomline="true">
+<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
+\begin_inset Text
+
+\layout Standard
+
+code
+\end_inset
+</cell>
+<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
+\begin_inset Text
+
+\layout Standard
+
+0
+\end_inset
+</cell>
+<cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
+\begin_inset Text
+
+\layout Standard
+
+0
+\end_inset
+</cell>
+<cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
+\begin_inset Text
+
+\layout Standard
+
+
+\family typewriter
+\shape slanted
+\emph on
+uxxxxx xxxxxxxx xxxxxxxx
+\end_inset
+</cell>
+<cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
+\begin_inset Text
+
+\layout Standard
+
+a 21-bit code pointer in FLASH memory
+\end_inset
+</cell>
+</row>
+<row bottomline="true">
+<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
+\begin_inset Text
+
+\layout Standard
+
+eeprom
+\end_inset
+</cell>
+<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
+\begin_inset Text
+
+\layout Standard
+
+0
+\end_inset
+</cell>
+<cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
+\begin_inset Text
+
+\layout Standard
+
+1
+\end_inset
+</cell>
+<cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
+\begin_inset Text
+
+\layout Standard
+
+
+\family typewriter
+\shape slanted
+\emph on
+uuuuuu uuuuuuxx xxxxxxxx
+\end_inset
+</cell>
+<cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
+\begin_inset Text
+
+\layout Standard
+
+a 10-bit eeprom pointer in EEPROM memory
+\end_inset
+</cell>
+</row>
+<row bottomline="true">
+<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
+\begin_inset Text
+
+\layout Standard
+
+(unimplemented)
+\end_inset
+</cell>
+<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
+\begin_inset Text
+
+\layout Standard
+
+1
+\end_inset
+</cell>
+<cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
+\begin_inset Text
+
+\layout Standard
+
+1
+\end_inset
+</cell>
+<cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
+\begin_inset Text
+
+\layout Standard
+
+
+\family typewriter
+\shape slanted
+\emph on
+xxxxxx xxxxxxxx xxxxxxxx
+\end_inset
+</cell>
+<cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
+\begin_inset Text
+
+\layout Standard
+
+unimplemented pointer type
+\end_inset
+</cell>
+</row>
+</lyxtabular>
+
+\end_inset
+
+
+\layout Standard
+
+Generic pointer are read and written with a set of library functions which
+ read/write 1, 2, 3, 4 bytes.
+\layout Subsection
+
+PIC16 C Libraries
+\layout Subsubsection
+
+Standard I/O Streams
+\layout Standard
+
+In the
+\emph on
+stdio.h
+\emph default
+ the type FILE is defined as:
+\layout LyX-Code
+
+typedef char * FILE;
+\layout Standard
+
+This type is the stream type implemented I/O in the PIC18F devices.
+ Also the standard input and output streams are declared in stdio.h:
+\layout LyX-Code
+
+extern FILE * stdin;
+\layout LyX-Code
+
+extern FILE * stdout;
+\layout Standard
+
+The FILE type is actually a generic pointer which defines one more type
+ of generic pointers, the
+\emph on
+stream
+\emph default
+pointer.
+ This new type has the format:
+\layout Standard
+\align center
+
+\begin_inset Tabular
+<lyxtabular version="3" rows="2" columns="7">
+<features>
+<column alignment="center" valignment="top" leftline="true" rightline="true" width="0">
+<column alignment="center" valignment="top" width="0">
+<column alignment="center" valignment="top" leftline="true" width="0">
+<column alignment="center" valignment="top" leftline="true" width="0">
+<column alignment="center" valignment="top" leftline="true" rightline="true" width="0">
+<column alignment="center" valignment="top" width="0">
+<column alignment="left" valignment="top" rightline="true" width="0">
+<row topline="true" bottomline="true">
+<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
+\begin_inset Text
+
+\layout Standard
+
+pointer type
+\end_inset
+</cell>
+<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
+\begin_inset Text
+
+\layout Standard
+
+<7:6>
+\end_inset
+</cell>
+<cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
+\begin_inset Text
+
+\layout Standard
+
+<5>
+\end_inset
+</cell>
+<cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
+\begin_inset Text
+
+\layout Standard
+
+<4>
+\end_inset
+</cell>
+<cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
+\begin_inset Text
+
+\layout Standard
+
+<3:0>
+\end_inset
+</cell>
+<cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
+\begin_inset Text
+
+\layout Standard
+
+rest of the pointer
+\end_inset
+</cell>
+<cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
+\begin_inset Text
+
+\layout Standard
+
+descrption
+\end_inset
+</cell>
+</row>
+<row topline="true" bottomline="true">
+<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
+\begin_inset Text
+
+\layout Standard
+
+stream
+\end_inset
+</cell>
+<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
+\begin_inset Text
+
+\layout Standard
+
+00
+\end_inset
+</cell>
+<cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
+\begin_inset Text
+
+\layout Standard
+
+1
+\end_inset
+</cell>
+<cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
+\begin_inset Text
+
+\layout Standard
+
+0
+\end_inset
+</cell>
+<cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
+\begin_inset Text
+
+\layout Standard
+
+nnnn
+\end_inset
+</cell>
+<cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
+\begin_inset Text
+
+\layout Standard
+
+
+\family typewriter
+\shape slanted
+\emph on
+uuuuuuuu uuuuuuuu
+\end_inset
+</cell>
+<cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
+\begin_inset Text
+
+\layout Standard
+
+upper byte high nubble is 0x2n, the rest are zeroes
+\end_inset
+</cell>
+</row>
+</lyxtabular>
+
+\end_inset
+
+
+\layout Standard
+
+Currently implemented there are 3 types of streams defined:
+\layout Standard
+\align center
+
+\begin_inset Tabular
+<lyxtabular version="3" rows="4" columns="4">
+<features>
+<column alignment="center" valignment="top" leftline="true" width="0">
+<column alignment="center" valignment="top" leftline="true" width="0">
+<column alignment="center" valignment="top" leftline="true" width="0">
+<column alignment="center" valignment="top" leftline="true" rightline="true" width="0">
+<row topline="true" bottomline="true">
+<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
+\begin_inset Text
+
+\layout Standard
+
+stream type
+\end_inset
+</cell>
+<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
+\begin_inset Text
+
+\layout Standard
+
+value
+\end_inset
+</cell>
+<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
+\begin_inset Text
+
+\layout Standard
+
+module
+\end_inset
+</cell>
+<cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
+\begin_inset Text
+
+\layout Standard
+
+description
+\end_inset
+</cell>
+</row>
+<row topline="true">
+<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
+\begin_inset Text
+
+\layout Standard
+
+STREAM_USART
+\end_inset
+</cell>
+<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
+\begin_inset Text
+
+\layout Standard
+
+
+\family typewriter
+0x200000UL
+\end_inset
+</cell>
+<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
+\begin_inset Text
+
+\layout Standard
+
+USART
+\end_inset
+</cell>
+<cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
+\begin_inset Text
+
+\layout Standard
+
+Writes/Reads characters via the USART peripheral
+\end_inset
+</cell>
+</row>
+<row topline="true">
+<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
+\begin_inset Text
+
+\layout Standard
+
+STREAM_MSSP
+\end_inset
+</cell>
+<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
+\begin_inset Text
+
+\layout Standard
+
+
+\family typewriter
+0x210000UL
+\end_inset
+</cell>
+<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
+\begin_inset Text
+
+\layout Standard
+
+MSSP
+\end_inset
+</cell>
+<cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
+\begin_inset Text
+
+\layout Standard
+
+Writes/Reads characters via the MSSP peripheral
+\end_inset
+</cell>
+</row>
+<row topline="true" bottomline="true">
+<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
+\begin_inset Text
+
+\layout Standard
+
+STREAM_USER
+\end_inset
+</cell>
+<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
+\begin_inset Text
+
+\layout Standard
+
+
+\family typewriter
+0x2f0000UL
+\end_inset
+</cell>
+<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
+\begin_inset Text
+
+\layout Standard
+
+(none)
+\end_inset
+</cell>
+<cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
+\begin_inset Text
+
+\layout Standard
+
+Writes/Reads characters via used defined functions
+\end_inset
+</cell>
+</row>
+</lyxtabular>
+
+\end_inset
+
+
+\layout Standard
+
+The stream identifiers are declared as macros in the stdio.h header.
+\layout Standard
+
+In the libc library there exist the functions that are used to write to
+ each of the above streams.
+ These are
+\layout List
+\labelwidthstring 00.00.0000
+
+_
+\begin_inset ERT
+status Collapsed
+
+\layout Standard
+
+\backslash
+/
+\end_inset
+
+_stream_usart_putchar writes a character at the USART stream
+\layout List
+\labelwidthstring 00.00.0000
+
+_
+\begin_inset ERT
+status Collapsed
+
+\layout Standard
+
+\backslash
+/
+\end_inset
+
+_stream_mssp_putchar writes a character at the MSSP stream
+\layout List
+\labelwidthstring 00.00.0000
+
+putchar dummy function.
+ This writes a character to a user specified manner.
+\layout Standard
+
+In order to increase performance
+\emph on
+putchar
+\emph default
+is declared in stdio.h as having its parameter in WREG (it has the wparam
+ keyword).
+ In stdio.h exists the macro PUTCHAR(arg) that defines the putchar function
+ in a user-friendly way.
+
+\emph on
+arg
+\emph default
+ is the name of the variable that holds the character to print.
+ An example follows:
+\layout LyX-Code
+
+#include <pic18fregs.h>
+\newline
+#include <stdio.h>
+\newline
+
+\newline
+PUTCHAR( c )
+\layout LyX-Code
+
+{
+\layout LyX-Code
+
+ PORTA = c; /* dump character c to PORTA */
+\layout LyX-Code
+
+}
+\newline
+
+\newline
+void main(void)
+\layout LyX-Code
+
+{
+\layout LyX-Code
+
+ stdout = STREAM_USER; /* this is not necessery, since stdout points
+\layout LyX-Code
+
+ * by default to STREAM_USER */
+\layout LyX-Code
+
+ printf (¨This is a printf test
+\backslash
+n¨);
+\layout LyX-Code
+
+}
+\layout LyX-Code
+
+\layout Subsubsection
+
+Printing functions
+\layout Standard
+
+PIC16 contains an implementation of the printf-family of functions.
+ There exist the following functions:
+\layout LyX-Code
+
+extern unsigned int sprintf(char *buf, char *fmt, ...);
+\layout LyX-Code
+
+extern unsigned int vsprintf(char *buf, char *fmt, va_list ap);
+\layout LyX-Code
+
+\layout LyX-Code
+
+extern unsigned int printf(char *fmt, ...);
+\layout LyX-Code
+
+extern unsigned int vprintf(char *fmt, va_lista ap);
+\layout LyX-Code
+
+\layout LyX-Code
+
+extern unsigned int fprintf(FILE *fp, char *fmt, ...);
+\layout LyX-Code
+
+extern unsigned int vfprintf(FILE *fp, char *fmt, va_list ap);
+\layout Standard
+
+For sprintf and vsprintf
+\emph on
+buf
+\emph default
+should normally be a data pointer where the resulting string will be placed.
+ No range checking is done so the user should allocate the necessery buffer.
+ For fprintf and vfprintf
+\emph on
+fp
+\emph default
+ should be a stream pointer (i.e.
+ stdout, STREAM_MSSP, etc...).
+\layout Subsubsection
+
+Signals
+\layout Standard
+
+The PIC18F family of microcontrollers supports a number of interrupt sources.
+ A list of these interrupts is shown in the following table:
+\layout Standard
+\align center
+
+\begin_inset Tabular
+<lyxtabular version="3" rows="11" columns="4">
+<features>
+<column alignment="left" valignment="top" leftline="true" width="0">
+<column alignment="center" valignment="top" leftline="true" rightline="true" width="0">
+<column alignment="left" valignment="top" leftline="true" width="0">
+<column alignment="center" valignment="top" leftline="true" rightline="true" width="0">
+<row topline="true" bottomline="true">
+<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
+\begin_inset Text
+
+\layout Standard
+
+signal name
+\end_inset
+</cell>
+<cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
+\begin_inset Text
+
+\layout Standard
+
+description
+\end_inset
+</cell>
+<cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
+\begin_inset Text
+
+\layout Standard
+
+signal name
+\end_inset
+</cell>
+<cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
+\begin_inset Text
+
+\layout Standard
+
+descritpion
+\end_inset
+</cell>
+</row>
+<row topline="true">
+<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
+\begin_inset Text
+
+\layout Standard
+
+SIG_RB
+\end_inset
+</cell>
+<cell multicolumn="1" alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
+\begin_inset Text
+
+\layout Standard
+
+PORTB change interrupt
+\end_inset
+</cell>
+<cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
+\begin_inset Text
+
+\layout Standard
+
+SIG_EE
+\end_inset
+</cell>
+<cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
+\begin_inset Text
+
+\layout Standard
+
+EEPROM/FLASH write complete interrupt
+\end_inset
+</cell>
+</row>
+<row topline="true">
+<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
+\begin_inset Text
+
+\layout Standard
+
+SIG_INT0
+\end_inset
+</cell>
+<cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
+\begin_inset Text
+
+\layout Standard
+
+INT0 external interrupt
+\end_inset
+</cell>
+<cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
+\begin_inset Text
+
+\layout Standard
+
+SIG_BCOL
+\end_inset
+</cell>
+<cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
+\begin_inset Text
+
+\layout Standard
+
+Bus collision interrupt
+\end_inset
+</cell>
+</row>
+<row topline="true">
+<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
+\begin_inset Text
+
+\layout Standard
+
+SIG_INT1
+\end_inset
+</cell>
+<cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
+\begin_inset Text
+
+\layout Standard
+
+INT1 external interrupt
+\end_inset
+</cell>
+<cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
+\begin_inset Text
+
+\layout Standard
+
+SIG_LVD
+\end_inset
+</cell>
+<cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
+\begin_inset Text
+
+\layout Standard
+
+Low voltage detect interrupt
+\end_inset
+</cell>
+</row>
+<row topline="true">
+<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
+\begin_inset Text
+
+\layout Standard
+
+SIG_INT2
+\end_inset
+</cell>
+<cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
+\begin_inset Text
+
+\layout Standard
+
+INT2 external interrupt
+\end_inset
+</cell>
+<cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
+\begin_inset Text
+
+\layout Standard
+
+SIG_PSP
+\end_inset
+</cell>
+<cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
+\begin_inset Text
+
+\layout Standard
+
+Parallel slave port interrupt
+\end_inset
+</cell>
+</row>
+<row topline="true">
+<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
+\begin_inset Text
+
+\layout Standard
+
+SIG_CCP1
+\end_inset
+</cell>
+<cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
+\begin_inset Text
+
+\layout Standard
+
+CCP1 module interrupt
+\end_inset
+</cell>
+<cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
+\begin_inset Text
+
+\layout Standard
+
+SIG_AD
+\end_inset
+</cell>
+<cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
+\begin_inset Text
+
+\layout Standard
+
+AD convertion complete interrupt
+\end_inset
+</cell>
+</row>
+<row topline="true">
+<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
+\begin_inset Text
+
+\layout Standard
+
+SIG_CCP2
+\end_inset
+</cell>
+<cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
+\begin_inset Text
+
+\layout Standard
+
+CCP2 module interrupt
+\end_inset
+</cell>
+<cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
+\begin_inset Text
+
+\layout Standard
+
+SIG_RC
+\end_inset
+</cell>
+<cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
+\begin_inset Text
+
+\layout Standard
+
+USART receive interrupt
+\end_inset
+</cell>
+</row>
+<row topline="true">
+<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
+\begin_inset Text
+
+\layout Standard
+
+SIG_TMR0
+\end_inset
+</cell>
+<cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
+\begin_inset Text
+
+\layout Standard
+
+TMR0 overflow interrupt
+\end_inset
+</cell>
+<cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
+\begin_inset Text
+
+\layout Standard
+
+SIG_TX
+\end_inset
+</cell>
+<cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
+\begin_inset Text
+
+\layout Standard
+
+USART transmit interrupt
+\end_inset
+</cell>
+</row>
+<row topline="true">
+<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
+\begin_inset Text
+
+\layout Standard
+
+SIG_TMR1
+\end_inset
+</cell>
+<cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
+\begin_inset Text
+
+\layout Standard
+
+TMR1 overflow interrupt
+\end_inset
+</cell>
+<cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
+\begin_inset Text
+
+\layout Standard
+
+SIG_MSSP
+\end_inset
+</cell>
+<cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
+\begin_inset Text
+
+\layout Standard
+
+SSP receive/transmit interrupt
+\end_inset
+</cell>
+</row>
+<row topline="true">
+<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
+\begin_inset Text
+
+\layout Standard
+
+SIG_TMR2
+\end_inset
+</cell>
+<cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
+\begin_inset Text
+
+\layout Standard
+
+TMR2 matches PR2 interrupt
+\end_inset
+</cell>
+<cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
+\begin_inset Text
+
+\layout Standard
+
+\end_inset
+</cell>
+<cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
+\begin_inset Text
+
+\layout Standard
+
+\end_inset
+</cell>
+</row>
+<row topline="true" bottomline="true">
+<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
+\begin_inset Text
+
+\layout Standard
+
+SIG_TMR3
+\end_inset
+</cell>
+<cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
+\begin_inset Text
+
+\layout Standard
+
+TMR3 overflow interrupt
+\end_inset
+</cell>
+<cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
+\begin_inset Text
+
+\layout Standard
+
+\end_inset
+</cell>
+<cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
+\begin_inset Text
+
+\layout Standard
+
+\end_inset
+</cell>
+</row>
+</lyxtabular>
+
+\end_inset
+
+
+\layout Standard
+
+The prototypes for these names are defined in the header file
+\emph on
+signal.h
+\emph default
+ .
+\layout Standard
+
+In order to simplify signal handling, a number of macros is provided:
+\layout List
+\labelwidthstring 00.00.0000
+
+DEF_INTHIGH(name) begin the definition of the interrupt dispatch table for
+ high priority interrupts.
+
+\emph on
+name
+\emph default
+ is the function name to use.
+\layout List
+\labelwidthstring 00.00.0000
+
+DEF_INTLOW(name) begin the definition of the interrupt dispatch table fo
+ low priority interrupt.
+
+\emph on
+name
+\emph default
+ is the function name to use.
+\layout List
+\labelwidthstring 00.00.0000
+
+DEF_HANDLER(sig,handler) define a handler for signal
+\emph on
+sig.
+\layout List
+\labelwidthstring 00.00.0000
+
+END_DEF end the declaration of the dispatch table.
+\layout Standard
+
+Additionally there are two more macros to simplify the declaration of the
+ signal handler:
+\layout List
+\labelwidthstring 00.00.0000
+
+
+\series medium
+SIGHANDLER(handler)
+\series default
+this declares the function prototype for the
+\emph on
+handler
+\emph default
+ function.
+\layout List
+\labelwidthstring 00.00.0000
+
+SIGHANDLERNAKED(handler) same as SIGHANDLER() but declares a naked function.
+\layout Standard
+
+An example of using the macros above is shown below:
+\layout LyX-Code
+
+#include <pic18fregs.h>
+\layout LyX-Code
+
+#include <signal.h>
+\newline
+
+\newline
+DEF_INTHIGH(high_int)
+\layout LyX-Code
+
+DEF_HANDLER(SIG_TMR0, _tmr0_handler)
+\layout LyX-Code
+
+DEF_HANDLER(SIG_BCOL, _bcol_handler)
+\layout LyX-Code
+
+END_DEF
+\newline
+
+\newline
+SIGHANDLER(_tmr0_handler)
+\layout LyX-Code
+
+{
+\layout LyX-Code
+
+ /* action to be taken when timer 0 overflows */
+\layout LyX-Code
+
+}
+\newline
+
+\newline
+SIGHANDLERNAKED(_bcol_handler)
+\layout LyX-Code
+
+{
+\layout LyX-Code
+
+ _asm
+\layout LyX-Code
+
+ /* action to be taken when bus collision occurs */
+\layout LyX-Code
+
+ retfie
+\layout LyX-Code
+
+ _endasm;
+\layout LyX-Code
+
+}
+\layout Standard
+
+
+\series bold
+NOTES:
+\series default
+ Special care should be taken when using the above scheme:
+\layout Itemize
+
+do not place a colon (;) at the end of the DEF_* and END_DEF macros.
+\layout Itemize
+
+when declaring SIGHANDLERNAKED handler never forget to use
+\emph on
+retfie
+\emph default
+ for proper returning.
+\layout Subsection
+
+PIC16 Port -- Tips
+\layout Standard
+
+Here you can find some general tips for compiling programs with SDCC/pic16.
+\layout Subsubsection
+
+Stack size
+\layout Standard
+
+The default stack size (that is 64 bytes) probably is enough for many programs.
+ One must take care that when there are many levels of function nesting,
+ or there is excessive usage of stack, its size should be extended.
+ An example of such a case is the printf/sprintf family of functions.
+ If you encounter problems like not being able to print integers, then you
+ need to set the stack size around the maximum (256 for small stack model).
+ The following diagram shows what happens when calling printf to print an
+ integer:
+\layout LyX-Code
+
+printf () --> ltoa () --> ultoa () --> divschar ()
+\layout Standard
+
+It is should be understood that stack is easily consumed when calling complicate
+d functions.
+ Using command line arguments like -
+\begin_inset ERT
+status Collapsed
+
+\layout Standard
+
+\backslash
+/
+\end_inset
+
+-fommit-frame-pointer might reduce stack usage by not creating unnecessery
+ stack frames.
+ Other ways to reduce stack usage may exist.
+\layout Chapter
+
+Debugging with SDCDB
+\begin_inset LatexCommand \label{cha:Debugging-with-SDCDB}
+
+\end_inset
+
+
+\begin_inset LatexCommand \index{sdcdb (debugger)}
+
+\end_inset
+
+
+\layout Standard
+
+SDCC is distributed with a source level debugger
+\begin_inset LatexCommand \index{Debugger}
+
+\end_inset
+
+.
+ The debugger uses a command line interface, the command repertoire of the
+ debugger has been kept as close to gdb
+\begin_inset LatexCommand \index{gdb}
+
+\end_inset
+
+ (the GNU debugger) as possible.
+ The configuration and build process is part of the standard compiler installati
+on, which also builds and installs the debugger in the target directory
+ specified during configuration.
+ The debugger allows you debug BOTH at the C source and at the ASM source
+ level.
+ Sdcdb is currently not available on Win32 platforms.
+\layout Section
+
+Compiling for Debugging
+\layout Standard
+
+The -
+\begin_inset ERT
+status Collapsed
+
+\layout Standard
+
+\backslash
+/
+\end_inset
+
+-debug
+\begin_inset LatexCommand \index{-\/-debug}
+
+\end_inset
+
+ option must be specified for all files for which debug information is to
+ be generated.
+ The complier generates a .adb file for each of these files.
+ The linker creates the .cdb
+\begin_inset LatexCommand \index{<file>.cdb}
+
+\end_inset
+
+ file from the .adb
+\begin_inset LatexCommand \index{<file>.adb}
+
+\end_inset
+
+ files and the address information.
+ This .cdb is used by the debugger.
+\layout Section
+
+How the Debugger Works
+\layout Standard
+
+When the -
+\begin_inset ERT
+status Collapsed
+
+\layout Standard
+
+\backslash
+/
+\end_inset
+
+-debug option is specified the compiler generates extra symbol information
+ some of which are put into the assembler source and some are put into the
+ .adb file.
+ Then the linker creates the .cdb file from the individual .adb files with
+ the address information for the symbols.
+ The debugger reads the symbolic information generated by the compiler &
+ the address information generated by the linker.
+ It uses the SIMULATOR (Daniel's S51) to execute the program, the program
+ execution is controlled by the debugger.
+ When a command is issued for the debugger, it translates it into appropriate
+ commands for the simulator.
+\layout Section
+
+Starting the Debugger
+\layout Standard
+
+The debugger can be started using the following command line.
+ (Assume the file you are debugging has the file name foo).
+\newline
+
+\newline
+
+\family sans
+\series bold
+sdcdb foo
+\newline
+
+\family default
+\series default
+
+\newline
+The debugger will look for the following files.
+\layout Itemize
+
+foo.c - the source file.
+\layout Itemize
+
+foo.cdb - the debugger symbol information file.
+\layout Itemize
+
+foo.ihx - the Intel hex format
+\begin_inset LatexCommand \index{Intel hex format}
+
+\end_inset
+
+ object file.
+\layout Section
+
+Command Line Options
+\layout Itemize
+
+-
+\begin_inset ERT
+status Collapsed
+
+\layout Standard
+
+\backslash
+/
+\end_inset
+
+-directory=<source file directory> this option can used to specify the directory
+ search list.
+ The debugger will look into the directory list specified for source, cdb
+ & ihx files.
+ The items in the directory list must be separated by ':', e.g.
+ if the source files can be in the directories /home/src1 and /home/src2,
+ the -
+\begin_inset ERT
+status Collapsed
+
+\layout Standard
+
+\backslash
+/
+\end_inset
+
+-directory option should be -
+\begin_inset ERT
+status Collapsed
+
+\layout Standard
+
+\backslash
+/
+\end_inset
+
+-directory=/home/src1:/home/src2.
+ Note there can be no spaces in the option.
+
+\layout Itemize
+
+-cd <directory> - change to the <directory>.
+\layout Itemize
+
+-fullname - used by GUI front ends.
+\layout Itemize
+
+-cpu <cpu-type> - this argument is passed to the simulator please see the
+ simulator docs for details.
+\layout Itemize
+
+-X <Clock frequency > this options is passed to the simulator please see
+ the simulator docs for details.
+\layout Itemize
+
+-s <serial port file> passed to simulator see the simulator docs for details.
+\layout Itemize
+
+-S <serial in,out> passed to simulator see the simulator docs for details.
+\layout Itemize
+
+-k <port number> passed to simulator see the simulator docs for details.
+\layout Section
+
+Debugger Commands
+\layout Standard
+
+As mentioned earlier the command interface for the debugger has been deliberatel
+y kept as close the GNU debugger gdb, as possible.
+ This will help the integration with existing graphical user interfaces
+ (like ddd, xxgdb or xemacs) existing for the GNU debugger.
+ If you use a graphical user interface for the debugger you can skip this
+ section.
+\layout Subsubsection*
+
+break [line | file:line | function | file:function]
+\layout Standard
+
+Set breakpoint at specified line or function:
+\newline
+
+\newline
+
+\family sans
+\series bold
+sdcdb>break 100
+\newline
+sdcdb>break foo.c:100
+\newline
+sdcdb>break funcfoo
+\newline
+sdcdb>break foo.c:funcfoo
+\layout Subsubsection*
+
+clear [line | file:line | function | file:function ]
+\layout Standard
+
+Clear breakpoint at specified line or function:
+\newline
+
+\newline
+
+\family sans
+\series bold
+sdcdb>clear 100
+\newline
+sdcdb>clear foo.c:100
+\newline
+sdcdb>clear funcfoo
+\newline
+sdcdb>clear foo.c:funcfoo
+\layout Subsubsection*
+
+continue
+\layout Standard
+
+Continue program being debugged, after breakpoint.
+\layout Subsubsection*
+
+finish
+\layout Standard
+
+Execute till the end of the current function.
+\layout Subsubsection*
+
+delete [n]
+\layout Standard
+
+Delete breakpoint number 'n'.
+ If used without any option clear ALL user defined break points.
+\layout Subsubsection*
+
+info [break | stack | frame | registers ]
+\layout Itemize
+
+info break - list all breakpoints
+\layout Itemize
+
+info stack - show the function call stack.
+\layout Itemize
+
+info frame - show information about the current execution frame.
+\layout Itemize
+
+info registers - show content of all registers.
+\layout Subsubsection*
+
+step
+\layout Standard
+
+Step program until it reaches a different source line.
+ Note: pressing <return> repeats the last command.
+\layout Subsubsection*
+
+next
+\layout Standard
+
+Step program, proceeding through subroutine calls.
+\layout Subsubsection*
+
+run
+\layout Standard
+
+Start debugged program.
+\layout Subsubsection*
+
+ptype variable
+\layout Standard
+
+Print type information of the variable.
+\layout Subsubsection*
+
+print variable
+\layout Standard
+
+print value of variable.
+\layout Subsubsection*
+
+file filename
+\layout Standard
+
+load the given file name.
+ Note this is an alternate method of loading file for debugging.
+\layout Subsubsection*
+
+frame
+\layout Standard
+
+print information about current frame.
+\layout Subsubsection*
+
+set srcmode
+\layout Standard
+
+Toggle between C source & assembly source.
+\layout Subsubsection*
+
+! simulator command
+\layout Standard
+
+Send the string following '!' to the simulator, the simulator response is
+ displayed.
+ Note the debugger does not interpret the command being sent to the simulator,
+ so if a command like 'go' is sent the debugger can loose its execution
+ context and may display incorrect values.
+\layout Subsubsection*
+
+quit
+\layout Standard
+
+"Watch me now.
+ Iam going Down.
+ My name is Bobby Brown"
+\layout Section
+
+Interfacing with DDD
+\layout Comment
+
+The screenshot was converted from png to eps with:
+\begin_inset Quotes sld
+\end_inset
+
+bmeps -c -e8f -p3 ddd_example.png >ddd_example.eps
+\begin_inset Quotes srd
+\end_inset
+
+ which produces a pretty compact eps file which is free from compression
+ artifacts.
+\layout Comment
+
+The screenshot was included in sdccman.lyx cvs version 1.120 but later removed
+ as this broke the build system on Sourceforge (pdf-file was broken).
+\layout Standard
+
+The .eps File
+\size footnotesize
+
+\begin_inset LatexCommand \url{http://svn.sourceforge.net/viewcvs.cgi/*checkout*/sdcc/trunk/sdcc/doc/figures/ddd_example.eps}
+
+\end_inset
+
+
+\size default
+ shows a screenshot of a debugging session with DDD
+\begin_inset LatexCommand \index{DDD (debugger)}
+
+\end_inset
+
+ (Unix only) on a simulated 8032.
+ The debugging session might not run as smoothly as the screenshot suggests.
+ The debugger allows setting of breakpoints, displaying and changing variables,
+ single stepping through C and assembler code.
+
+\newline
+The source was compiled with
+\family sans
+\series bold
+
+\newline
+
+\newline
+sdcc -
+\family default
+\series default
+
+\begin_inset ERT
+status Collapsed
+
+\layout Standard
+
+\backslash
+/
+\end_inset
+
+
+\family sans
+\series bold
+-debug ddd_example.c
+\family default
+\series default
+
+\family sans
+\series bold
+
+\newline
+
+\family default
+\series default
+
+\newline
+and DDD was invoked with
+\family sans
+\series bold
+
+\newline
+
+\newline
+ddd -debugger 'sdcdb -cpu 8032 ddd_example'
+\layout Section
+
+Interfacing with XEmacs
+\begin_inset LatexCommand \index{XEmacs}
+
+\end_inset
+
+
+\begin_inset LatexCommand \index{Emacs}
+
+\end_inset
+
+
+\layout Standard
+
+Two files (in emacs lisp) are provided for the interfacing with XEmacs,
+ sdcdb.el and sdcdbsrc.el.
+ These two files can be found in the $(prefix)/bin directory after the installat
+ion is complete.
+ These files need to be loaded into XEmacs for the interface to work.
+ This can be done at XEmacs startup time by inserting the following into
+ your '.xemacs' file (which can be found in your HOME directory):
+\newline
+
+\newline
+
+\family typewriter
+(load-file sdcdbsrc.el)
+\family default
+
+\newline
+
+\newline
+.xemacs is a lisp file so the () around the command is REQUIRED.
+ The files can also be loaded dynamically while XEmacs is running, set the
+ environment variable 'EMACSLOADPATH' to the installation bin directory
+ (<installdir>/bin), then enter the following command ESC-x load-file sdcdbsrc.
+ To start the interface enter the following command:
+\newline
+
+\newline
+
+\family sans
+\series bold
+ESC-x sdcdbsrc
+\family default
+\series default
+
+\newline
+
+\newline
+You will prompted to enter the file name to be debugged.
+
+\newline
+
+\newline
+The command line options that are passed to the simulator directly are bound
+ to default values in the file sdcdbsrc.el.
+ The variables are listed below, these values maybe changed as required.
+\layout Itemize
+
+sdcdbsrc-cpu-type '51
+\layout Itemize
+
+sdcdbsrc-frequency '11059200
+\layout Itemize
+
+sdcdbsrc-serial nil
+\layout Standard
+
+The following is a list of key mapping for the debugger interface.
+\layout Standard
+
+\SpecialChar ~
+
+\family typewriter
+
+\newline
+;;\SpecialChar ~
+Current Listing ::
+\newline
+;;key\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+binding\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
\SpecialChar ~
\SpecialChar ~
\SpecialChar ~
\SpecialChar ~
\SpecialChar ~
\SpecialChar ~
+Comment
+\newline
+;;---\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+-------\SpecialChar ~
\SpecialChar ~
\SpecialChar ~
\SpecialChar ~
\SpecialChar ~
\SpecialChar ~
\SpecialChar ~
---------
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+-------
\newline
;;
\newline
-;; n\SpecialChar ~
+;;\SpecialChar ~
+n\SpecialChar ~
+\SpecialChar ~
\SpecialChar ~
\SpecialChar ~
\SpecialChar ~
\SpecialChar ~
\SpecialChar ~
\SpecialChar ~
- sdcdb-next-from-src\SpecialChar ~
+sdcdb-next-from-src\SpecialChar ~
\SpecialChar ~
\SpecialChar ~
\SpecialChar ~
\SpecialChar ~
SDCDB next command
\newline
-;; b\SpecialChar ~
+;;\SpecialChar ~
+b\SpecialChar ~
+\SpecialChar ~
\SpecialChar ~
\SpecialChar ~
\SpecialChar ~
\SpecialChar ~
\SpecialChar ~
\SpecialChar ~
- sdcdb-back-from-src\SpecialChar ~
+sdcdb-back-from-src\SpecialChar ~
\SpecialChar ~
\SpecialChar ~
\SpecialChar ~
\SpecialChar ~
SDCDB back command
\newline
-;; c\SpecialChar ~
+;;\SpecialChar ~
+c\SpecialChar ~
+\SpecialChar ~
\SpecialChar ~
\SpecialChar ~
\SpecialChar ~
\SpecialChar ~
\SpecialChar ~
\SpecialChar ~
- sdcdb-cont-from-src\SpecialChar ~
+sdcdb-cont-from-src\SpecialChar ~
\SpecialChar ~
\SpecialChar ~
\SpecialChar ~
\SpecialChar ~
SDCDB continue command
\newline
-;; s\SpecialChar ~
+;;\SpecialChar ~
+s\SpecialChar ~
+\SpecialChar ~
\SpecialChar ~
\SpecialChar ~
\SpecialChar ~
\SpecialChar ~
\SpecialChar ~
\SpecialChar ~
- sdcdb-step-from-src\SpecialChar ~
+sdcdb-step-from-src\SpecialChar ~
\SpecialChar ~
\SpecialChar ~
\SpecialChar ~
\SpecialChar ~
SDCDB step command
\newline
-;; ?\SpecialChar ~
+;;\SpecialChar ~
+?\SpecialChar ~
+\SpecialChar ~
\SpecialChar ~
\SpecialChar ~
\SpecialChar ~
\SpecialChar ~
\SpecialChar ~
\SpecialChar ~
- sdcdb-whatis-c-sexp\SpecialChar ~
+sdcdb-whatis-c-sexp\SpecialChar ~
\SpecialChar ~
\SpecialChar ~
\SpecialChar ~
\SpecialChar ~
\SpecialChar ~
\SpecialChar ~
- buffer point
+\SpecialChar ~
+buffer point
\newline
-;; x\SpecialChar ~
+;;\SpecialChar ~
+x\SpecialChar ~
+\SpecialChar ~
\SpecialChar ~
\SpecialChar ~
\SpecialChar ~
\SpecialChar ~
\SpecialChar ~
\SpecialChar ~
- sdcdbsrc-delete\SpecialChar ~
+sdcdbsrc-delete\SpecialChar ~
\SpecialChar ~
\SpecialChar ~
\SpecialChar ~
\SpecialChar ~
\SpecialChar ~
\SpecialChar ~
+\SpecialChar ~
given or delete arg (C-u arg x)
\newline
-;; m\SpecialChar ~
+;;\SpecialChar ~
+m\SpecialChar ~
\SpecialChar ~
\SpecialChar ~
\SpecialChar ~
\SpecialChar ~
\SpecialChar ~
\SpecialChar ~
- sdcdbsrc-frame\SpecialChar ~
+\SpecialChar ~
+sdcdbsrc-frame\SpecialChar ~
\SpecialChar ~
\SpecialChar ~
\SpecialChar ~
\SpecialChar ~
buffer point
\newline
-;; !\SpecialChar ~
+;;\SpecialChar ~
+!\SpecialChar ~
\SpecialChar ~
\SpecialChar ~
\SpecialChar ~
\SpecialChar ~
\SpecialChar ~
\SpecialChar ~
- sdcdbsrc-goto-sdcdb\SpecialChar ~
+\SpecialChar ~
+sdcdbsrc-goto-sdcdb\SpecialChar ~
\SpecialChar ~
\SpecialChar ~
\SpecialChar ~
\SpecialChar ~
Goto the SDCDB output buffer
\newline
-;; p\SpecialChar ~
+;;\SpecialChar ~
+p\SpecialChar ~
\SpecialChar ~
\SpecialChar ~
\SpecialChar ~
\SpecialChar ~
\SpecialChar ~
\SpecialChar ~
- sdcdb-print-c-sexp\SpecialChar ~
+\SpecialChar ~
+sdcdb-print-c-sexp\SpecialChar ~
\SpecialChar ~
\SpecialChar ~
\SpecialChar ~
\SpecialChar ~
\SpecialChar ~
\SpecialChar ~
- buffer point
+\SpecialChar ~
+buffer point
+\newline
+;;\SpecialChar ~
+g\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+sdcdbsrc-goto-sdcdb\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+Goto the SDCDB output buffer
\newline
-;; g\SpecialChar ~
+;;\SpecialChar ~
+t\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+sdcdbsrc-mode\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
\SpecialChar ~
\SpecialChar ~
\SpecialChar ~
\SpecialChar ~
\SpecialChar ~
\SpecialChar ~
+Toggles Sdcdbsrc mode (turns it off)
+\newline
+;;
+\newline
+;;\SpecialChar ~
+C-c\SpecialChar ~
+C-f\SpecialChar ~
\SpecialChar ~
\SpecialChar ~
\SpecialChar ~
\SpecialChar ~
\SpecialChar ~
\SpecialChar ~
- sdcdbsrc-goto-sdcdb\SpecialChar ~
\SpecialChar ~
\SpecialChar ~
+sdcdb-finish-from-src\SpecialChar ~
\SpecialChar ~
\SpecialChar ~
\SpecialChar ~
\SpecialChar ~
\SpecialChar ~
\SpecialChar ~
-Goto the SDCDB output buffer
+SDCDB finish command
+\newline
+;;
\newline
-;; t\SpecialChar ~
+;;\SpecialChar ~
+C-x\SpecialChar ~
+SPC\SpecialChar ~
\SpecialChar ~
\SpecialChar ~
\SpecialChar ~
\SpecialChar ~
\SpecialChar ~
\SpecialChar ~
+sdcdb-break\SpecialChar ~
\SpecialChar ~
\SpecialChar ~
\SpecialChar ~
\SpecialChar ~
\SpecialChar ~
- sdcdbsrc-mode\SpecialChar ~
\SpecialChar ~
\SpecialChar ~
\SpecialChar ~
\SpecialChar ~
\SpecialChar ~
\SpecialChar ~
+Set break for line with point
+\newline
+;;\SpecialChar ~
+ESC\SpecialChar ~
+t\SpecialChar ~
\SpecialChar ~
\SpecialChar ~
\SpecialChar ~
-Toggles Sdcdbsrc mode (turns it off)
-\newline
-;;
-\newline
-;; C-c C-f\SpecialChar ~
\SpecialChar ~
\SpecialChar ~
\SpecialChar ~
\SpecialChar ~
\SpecialChar ~
\SpecialChar ~
- sdcdb-finish-from-src\SpecialChar ~
+sdcdbsrc-mode\SpecialChar ~
+\SpecialChar ~
\SpecialChar ~
\SpecialChar ~
\SpecialChar ~
\SpecialChar ~
\SpecialChar ~
\SpecialChar ~
-SDCDB finish command
-\newline
-;;
-\newline
-;; C-x SPC\SpecialChar ~
\SpecialChar ~
\SpecialChar ~
\SpecialChar ~
\SpecialChar ~
\SpecialChar ~
\SpecialChar ~
- sdcdb-break\SpecialChar ~
+Toggle Sdcdbsrc mode
+\newline
+;;\SpecialChar ~
+ESC\SpecialChar ~
+m\SpecialChar ~
+\SpecialChar ~
\SpecialChar ~
\SpecialChar ~
\SpecialChar ~
\SpecialChar ~
\SpecialChar ~
\SpecialChar ~
+sdcdbsrc-srcmode\SpecialChar ~
\SpecialChar ~
\SpecialChar ~
\SpecialChar ~
\SpecialChar ~
\SpecialChar ~
\SpecialChar ~
-Set break for line with point
-\newline
-;; ESC t\SpecialChar ~
\SpecialChar ~
\SpecialChar ~
\SpecialChar ~
\SpecialChar ~
+Toggle list mode
+\newline
+;;
+\newline
+
+\layout Chapter
+\pagebreak_top
+TIPS
+\layout Standard
+
+Here are a few guidelines that will help the compiler generate more efficient
+ code, some of the tips are specific to this compiler others are generally
+ good programming practice.
+\layout Itemize
+
+Use the smallest data type to represent your data-value.
+ If it is known in advance that the value is going to be less than 256 then
+ use an 'unsigned char' instead of a 'short' or 'int'.
+ Please note, that ANSI C requires both signed and unsigned chars to be
+ promoted to 'signed int' before doing any operation.
+ This promotion
+\begin_inset LatexCommand \index{type promotion}
+
+\end_inset
+
+ can be omitted, if the result is the same.
+ The effect of the promotion rules together with the sign-extension is often
+ surprising:
+\begin_deeper
+\layout Verse
+
+
+\family typewriter
+unsigned char uc = 0xfe;
+\newline
+if (uc * uc < 0) /* this is true! */
+\newline
+{
+\newline
\SpecialChar ~
\SpecialChar ~
\SpecialChar ~
\SpecialChar ~
+....
+\newline
+}
+\layout Standard
+
+
+\family typewriter
+uc * uc
+\family default
+ is evaluated as
+\family typewriter
+(int) uc * (int) uc = (int) 0xfe * (int) 0xfe = (int) 0xfc04 = -1024
+\family default
+.
+
+\newline
+Another one:
+\layout Verse
+
+
+\family typewriter
+(unsigned char) -12 / (signed char) -3 = ...
+\layout Standard
+
+No, the result is not 4:
+\layout Verse
+
+
+\family typewriter
+(int) (unsigned char) -12 / (int) (signed char) -3 =
+\newline
+(int) (unsigned char) 0xf4 / (int) (signed char) 0xfd =
+\newline
+(int) 0x00f4 / (int) 0xfffd =
+\newline
+(int) 0x00f4 / (int) 0xfffd =
+\newline
+(int) 244 / (int) -3 =
+\newline
+(int) -81 = (int) 0xffaf;
+\layout Standard
+
+Don't complain, that gcc gives you a different result.
+ gcc uses 32 bit ints, while SDCC uses 16 bit ints.
+ Therefore the results are different.
+\newline
+From
+\begin_inset Quotes sld
+\end_inset
+
+comp.lang.c FAQ
+\begin_inset Quotes srd
+\end_inset
+
+:
+\layout Quote
+
+If well-defined overflow characteristics are important and negative values
+ are not, or if you want to steer clear of sign-extension problems when
+ manipulating bits or bytes, use one of the corresponding unsigned types.
+ (Beware when mixing signed and unsigned values in expressions, though.)
+\newline
+Although character types (especially unsigned char) can be used as "tiny"
+ integers, doing so is sometimes more trouble than it's worth, due to unpredicta
+ble sign extension and increased code size.
+\end_deeper
+\layout Itemize
+
+Use unsigned when it is known in advance that the value is not going to
+ be negative.
+ This helps especially if you are doing division or multiplication, bit-shifting
+ or are using an array index.
+\layout Itemize
+
+NEVER jump into a LOOP.
+\layout Itemize
+
+Declare the variables to be local
+\begin_inset LatexCommand \index{local variables}
+
+\end_inset
+
+ whenever possible, especially loop control variables (induction).
+\layout Itemize
+
+Since the compiler does not always do implicit integral promotion, the programme
+r should do an explicit cast when integral promotion is required.
+\layout Itemize
+
+Reducing the size of division, multiplication & modulus operations can reduce
+ code size substantially.
+ Take the following code for example.
+\begin_deeper
+\layout Verse
+
+
+\family typewriter
+foobar(unsigned int p1, unsigned char ch)
+\newline
+{
+\newline
\SpecialChar ~
- sdcdbsrc-mode\SpecialChar ~
\SpecialChar ~
\SpecialChar ~
\SpecialChar ~
+unsigned char ch1 = p1 % ch ;
+\newline
\SpecialChar ~
\SpecialChar ~
\SpecialChar ~
\SpecialChar ~
+....
+\newline
+}
+\layout Standard
+
+For the modulus operation the variable ch will be promoted to unsigned int
+ first then the modulus operation will be performed (this will lead to a
+ call to support routine _moduint()), and the result will be casted to a
+ char.
+ If the code is changed to
+\layout Verse
+
+
+\family typewriter
+foobar(unsigned int p1, unsigned char ch)
+\newline
+{
+\newline
\SpecialChar ~
\SpecialChar ~
\SpecialChar ~
\SpecialChar ~
+unsigned char ch1 = (unsigned char)p1 % ch ;
+\newline
\SpecialChar ~
\SpecialChar ~
\SpecialChar ~
\SpecialChar ~
-Toggle Sdcdbsrc mode
+....
+\newline
+}
+\layout Standard
+
+It would substantially reduce the code generated (future versions of the
+ compiler will be smart enough to detect such optimization opportunities).
+\end_deeper
+\layout Itemize
+
+Have a look at the assembly listing to get a
+\begin_inset Quotes sld
+\end_inset
+
+feeling
+\begin_inset Quotes srd
+\end_inset
+
+ for the code generation.
+\layout Section
+
+Tools
+\begin_inset LatexCommand \index{Tools}
+
+\end_inset
+
+ included in the distribution
+\layout Standard
+\align center
+
+\begin_inset Tabular
+<lyxtabular version="3" rows="12" columns="3">
+<features>
+<column alignment="center" valignment="top" leftline="true" width="0pt">
+<column alignment="center" valignment="top" leftline="true" width="0pt">
+<column alignment="left" valignment="top" leftline="true" rightline="true" width="0pt">
+<row topline="true" bottomline="true">
+<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
+\begin_inset Text
+
+\layout Standard
+
+Name
+\end_inset
+</cell>
+<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
+\begin_inset Text
+
+\layout Standard
+
+Purpose
+\end_inset
+</cell>
+<cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
+\begin_inset Text
+
+\layout Standard
+
+Directory
+\end_inset
+</cell>
+</row>
+<row topline="true">
+<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
+\begin_inset Text
+
+\layout Standard
+
+uCsim
+\end_inset
+</cell>
+<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
+\begin_inset Text
+
+\layout Standard
+
+Simulator for various architectures
+\end_inset
+</cell>
+<cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
+\begin_inset Text
+
+\layout Standard
+
+sdcc/sim/ucsim
+\end_inset
+</cell>
+</row>
+<row topline="true">
+<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
+\begin_inset Text
+
+\layout Standard
+
+keil2sdcc.pl
+\end_inset
+</cell>
+<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
+\begin_inset Text
+
+\layout Standard
+
+header file conversion
+\end_inset
+</cell>
+<cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
+\begin_inset Text
+
+\layout Standard
+
+sdcc/support/scripts
+\end_inset
+</cell>
+</row>
+<row topline="true">
+<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
+\begin_inset Text
+
+\layout Standard
+
+mh2h.c
+\end_inset
+</cell>
+<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
+\begin_inset Text
+
+\layout Standard
+
+header file conversion
+\end_inset
+</cell>
+<cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
+\begin_inset Text
+
+\layout Standard
+
+sdcc/support/scripts
+\end_inset
+</cell>
+</row>
+<row topline="true">
+<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
+\begin_inset Text
+
+\layout Standard
+
+as-gbz80
+\end_inset
+</cell>
+<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
+\begin_inset Text
+
+\layout Standard
+
+Assembler
+\end_inset
+</cell>
+<cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
+\begin_inset Text
+
+\layout Standard
+
+
+\family roman
+\series medium
+\shape up
+\size normal
+\emph off
+\bar no
+\noun off
+\color none
+sdcc/bin
+\end_inset
+</cell>
+</row>
+<row topline="true">
+<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
+\begin_inset Text
+
+\layout Standard
+
+as-z80
+\end_inset
+</cell>
+<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
+\begin_inset Text
+
+\layout Standard
+
+Assembler
+\end_inset
+</cell>
+<cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
+\begin_inset Text
+
+\layout Standard
+
+
+\family roman
+\series medium
+\shape up
+\size normal
+\emph off
+\bar no
+\noun off
+\color none
+sdcc/bin
+\end_inset
+</cell>
+</row>
+<row topline="true">
+<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
+\begin_inset Text
+
+\layout Standard
+
+asx8051
+\end_inset
+</cell>
+<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
+\begin_inset Text
+
+\layout Standard
+
+Assembler
+\end_inset
+</cell>
+<cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
+\begin_inset Text
+
+\layout Standard
+
+
+\family roman
+\series medium
+\shape up
+\size normal
+\emph off
+\bar no
+\noun off
+\color none
+sdcc/bin
+\end_inset
+</cell>
+</row>
+<row topline="true">
+<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
+\begin_inset Text
+
+\layout Standard
+
+sdcdb
+\end_inset
+</cell>
+<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
+\begin_inset Text
+
+\layout Standard
+
+Simulator
+\end_inset
+</cell>
+<cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
+\begin_inset Text
+
+\layout Standard
+
+
+\family roman
+\series medium
+\shape up
+\size normal
+\emph off
+\bar no
+\noun off
+\color none
+sdcc/bin
+\end_inset
+</cell>
+</row>
+<row topline="true">
+<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
+\begin_inset Text
+
+\layout Standard
+
+aslink
+\end_inset
+</cell>
+<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
+\begin_inset Text
+
+\layout Standard
+
+Linker
+\end_inset
+</cell>
+<cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
+\begin_inset Text
+
+\layout Standard
+
+
+\family roman
+\series medium
+\shape up
+\size normal
+\emph off
+\bar no
+\noun off
+\color none
+sdcc/bin
+\end_inset
+</cell>
+</row>
+<row topline="true">
+<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
+\begin_inset Text
+
+\layout Standard
+
+link-z80
+\end_inset
+</cell>
+<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
+\begin_inset Text
+
+\layout Standard
+
+Linker
+\end_inset
+</cell>
+<cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
+\begin_inset Text
+
+\layout Standard
+
+
+\family roman
+\series medium
+\shape up
+\size normal
+\emph off
+\bar no
+\noun off
+\color none
+sdcc/bin
+\end_inset
+</cell>
+</row>
+<row topline="true">
+<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
+\begin_inset Text
+
+\layout Standard
+
+link-gbz80
+\end_inset
+</cell>
+<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
+\begin_inset Text
+
+\layout Standard
+
+Linker
+\end_inset
+</cell>
+<cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
+\begin_inset Text
+
+\layout Standard
+
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+packihx
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+ihx packer
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+\layout Standard
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+</row>
+</lyxtabular>
+
+\end_inset
+
+
\newline
-;; ESC m\SpecialChar ~
-\SpecialChar ~
-\SpecialChar ~
-\SpecialChar ~
-\SpecialChar ~
-\SpecialChar ~
-\SpecialChar ~
-\SpecialChar ~
-\SpecialChar ~
-\SpecialChar ~
- sdcdbsrc-srcmode\SpecialChar ~
-\SpecialChar ~
-\SpecialChar ~
-\SpecialChar ~
-\SpecialChar ~
-\SpecialChar ~
-\SpecialChar ~
-\SpecialChar ~
-\SpecialChar ~
-\SpecialChar ~
-\SpecialChar ~
-\SpecialChar ~
- Toggle list mode
+
+\layout Section
+
+Documentation
+\begin_inset LatexCommand \index{Documentation}
+
+\end_inset
+
+ included in the distribution
+\layout Standard
+\align center
+
+\begin_inset Tabular
+<lyxtabular version="3" rows="10" columns="2">
+<features>
+<column alignment="left" valignment="top" leftline="true" width="0">
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+\layout Standard
+
+Subject / Title
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+<cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
+\begin_inset Text
+
+\layout Standard
+
+Where to get / filename
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+<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
+\begin_inset Text
+
+\layout Standard
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+SDCC Compiler User Guide
+\end_inset
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+<cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
+\begin_inset Text
+
+\layout Standard
+
+You're reading it right now
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+
+\layout Standard
+
+Changelog of SDCC
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+sdcc/Changelog
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+\layout Standard
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+ASXXXX
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+
+\end_inset
+
+
+\begin_inset LatexCommand \index{Assembler documentation}
+
+\end_inset
+
+ Assemblers and ASLINK
+\begin_inset LatexCommand \index{aslink}
+
+\end_inset
+
+
+\begin_inset LatexCommand \index{Linker documentation}
+
+\end_inset
+
+ Relocating Linker
+\end_inset
+</cell>
+<cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
+\begin_inset Text
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+sdcc/as/doc/asxhtm.html
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+
+\layout Standard
+
+SDCC regression test
+\begin_inset LatexCommand \index{Regression test}
+
+\end_inset
+
+
+\end_inset
+</cell>
+<cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
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+sdcc/doc/test_suite_spec.pdf
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+\layout Standard
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+Various notes
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+\layout Standard
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+sdcc/doc/*
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+\begin_inset Text
+
+\layout Standard
+
+Notes on debugging with sdcdb
+\begin_inset LatexCommand \index{sdcdb (debugger)}
+
+\end_inset
+
+
+\end_inset
+</cell>
+<cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
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+\layout Standard
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+sdcc/debugger/README
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+Software simulator for microcontrollers
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+\layout Standard
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+<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
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+
+\layout Standard
+
+Temporary notes on the pic16
+\begin_inset LatexCommand \index{PIC16}
+
+\end_inset
+
+ port
+\end_inset
+</cell>
+<cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
+\begin_inset Text
+
+\layout Standard
+
+sdcc/src/pic16/NOTES
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+</row>
+<row topline="true" bottomline="true">
+<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
+\begin_inset Text
+
+\layout Standard
+
+SDCC internal documentation (debugging file format)
+\end_inset
+</cell>
+<cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
+\begin_inset Text
+
+\layout Standard
+
+sdcc/doc/
+\family roman
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+\emph off
+\bar no
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+\color none
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+f
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+</cell>
+</row>
+</lyxtabular>
+
+\end_inset
+
+
\newline
-;;
+
+\layout Section
+
+Related open source tools
+\begin_inset LatexCommand \index{Related tools}
+
+\end_inset
+
+
+\layout Standard
+\align center
+
+\begin_inset Tabular
+<lyxtabular version="3" rows="11" columns="3">
+<features>
+<column alignment="center" valignment="top" leftline="true" width="0pt">
+<column alignment="block" valignment="top" leftline="true" width="30line%">
+<column alignment="left" valignment="top" leftline="true" rightline="true" width="0pt">
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+\layout Standard
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+Name
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+<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
+\begin_inset Text
+
+\layout Standard
+
+Purpose
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+</cell>
+<cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
+\begin_inset Text
+
+\layout Standard
+
+Where to get
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+<row topline="true">
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+
+\layout Standard
+
+gpsim
+\begin_inset LatexCommand \index{gpsim (pic simulator)}
+
+\end_inset
+
+
+\end_inset
+</cell>
+<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
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+
+\layout Standard
+
+PIC simulator
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+<cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
+\begin_inset Text
+
+\layout Standard
+
+
+\begin_inset LatexCommand \url{http://www.dattalo.com/gnupic/gpsim.html}
+
+\end_inset
+
+
+\end_inset
+</cell>
+</row>
+<row topline="true">
+<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
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+
+\layout Standard
+
+gputils
+\begin_inset LatexCommand \index{gputils (pic tools)}
+
+\end_inset
+
+
+\end_inset
+</cell>
+<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
+\begin_inset Text
+
+\layout Standard
+
+GNU PIC utilities
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+<cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
+\begin_inset Text
+
+\layout Standard
+
+
+\begin_inset LatexCommand \url{http://sourceforge.net/projects/gputils}
+
+\end_inset
+
+
+\end_inset
+</cell>
+</row>
+<row topline="true">
+<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
+\begin_inset Text
+
+\layout Standard
+
+flP5
+\end_inset
+</cell>
+<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
+\begin_inset Text
+
+\layout Standard
+
+PIC programmer
+\end_inset
+</cell>
+<cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
+\begin_inset Text
+
+\layout Standard
+
+
+\begin_inset LatexCommand \url{http://freshmeat.net/projects/flp5/}
+
+\end_inset
+
+
+\end_inset
+</cell>
+</row>
+<row topline="true">
+<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
+\begin_inset Text
+
+\layout Standard
+
+indent
+\begin_inset LatexCommand \index{indent (source formatting tool)}
+
+\end_inset
+
+
+\end_inset
+</cell>
+<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
+\begin_inset Text
+
+\layout Standard
+
+Formats C source - Master of the white spaces
+\end_inset
+</cell>
+<cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
+\begin_inset Text
+
+\layout Standard
+
+
+\begin_inset LatexCommand \url{http://directory.fsf.org/GNU/indent.html}
+
+\end_inset
+
+
+\end_inset
+</cell>
+</row>
+<row topline="true">
+<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
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+
+\layout Standard
+
+srecord
+\begin_inset LatexCommand \index{srecord (bin, hex, ... tool)}
+
+\end_inset
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+
+\end_inset
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+<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
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+Object file conversion, checksumming, ...
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+\layout Standard
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+
+\begin_inset LatexCommand \url{http://sourceforge.net/projects/srecord}
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+\end_inset
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+
+\end_inset
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+\layout Standard
+
+objdump
+\begin_inset LatexCommand \index{objdump (tool)}
+
+\end_inset
+
+
+\end_inset
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+
+Object file conversion, ...
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+<cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
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+
+\layout Standard
+
+Part of binutils (should be there anyway)
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+</cell>
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+<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
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+\layout Standard
+
+doxygen
+\begin_inset LatexCommand \index{doxygen (source documentation tool)}
+
+\end_inset
+
+
+\end_inset
+</cell>
+<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
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+
+\layout Standard
+
+Source code documentation system
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+
+\layout Standard
+
+
+\begin_inset LatexCommand \url{http://www.doxygen.org}
+
+\end_inset
+
+
+\end_inset
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+<row topline="true">
+<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
+\begin_inset Text
+
+\layout Standard
+
+kdevelop
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+</cell>
+<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
+\begin_inset Text
+
+\layout Standard
+
+IDE (has anyone tried integrating SDCC & sdcdb? Unix only)
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+<cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
+\begin_inset Text
+
+\layout Standard
+
+
+\begin_inset LatexCommand \url{http://www.kdevelop.org}
+
+\end_inset
+
+
+\end_inset
+</cell>
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+<row topline="true">
+<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
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+\layout Standard
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+splint
+\begin_inset LatexCommand \index{splint (syntax checking tool)}
+
+\end_inset
+
+
+\end_inset
+</cell>
+<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
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+\layout Standard
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+Statically checks c sources (see
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+
+\end_inset
+
+)
+\end_inset
+</cell>
+<cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
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+
+\layout Standard
+
+
+\begin_inset LatexCommand \url{http://www.splint.org}
+
+\end_inset
+
+
+\end_inset
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+<row topline="true" bottomline="true">
+<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
+\begin_inset Text
+
+\layout Standard
+
+ddd
+\begin_inset LatexCommand \index{ddd (debugger)}
+
+\end_inset
+
+
+\end_inset
+</cell>
+<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
+\begin_inset Text
+
+\layout Standard
+
+Debugger, serves nicely as GUI to sdcdb
+\begin_inset LatexCommand \index{sdcdb (debugger)}
+
+\end_inset
+
+ (Unix only)
+\end_inset
+</cell>
+<cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
+\begin_inset Text
+
+\layout Standard
+
+
+\begin_inset LatexCommand \url{http://www.gnu.org/software/ddd/}
+
+\end_inset
+
+
+\end_inset
+</cell>
+</row>
+</lyxtabular>
+
+\end_inset
+
+
\newline
-\layout Chapter
-\pagebreak_top
-TIPS
+\layout Section
+
+Related documentation / recommended reading
+\layout Standard
+\align center
+
+\begin_inset Tabular
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+<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
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+\layout Standard
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+Subject / Title
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+<cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
+\begin_inset Text
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+\layout Standard
+
+Where to get
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+<row topline="true">
+<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
+\begin_inset Text
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+\layout Standard
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+
+\family roman
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+\bar no
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+\color none
+c-refcard.pdf
+\end_inset
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+<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
+\begin_inset Text
+
+\layout Standard
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+C Reference Card
+\begin_inset LatexCommand \index{C Reference card}
+
+\end_inset
+
+, 2 pages
+\end_inset
+</cell>
+<cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
+\begin_inset Text
+
\layout Standard
-Here are a few guidelines that will help the compiler generate more efficient
- code, some of the tips are specific to this compiler others are generally
- good programming practice.
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-Use the smallest data type to represent your data-value.
- If it is known in advance that the value is going to be less than 256 then
- use an 'unsigned char' instead of a 'short' or 'int'.
-\layout Itemize
+\begin_inset LatexCommand \url{http://refcards.com/refcards/c/index.html}
-Use unsigned when it is known in advance that the value is not going to
- be negative.
- This helps especially if you are doing division or multiplication.
-\layout Itemize
+\end_inset
-NEVER jump into a LOOP.
-\layout Itemize
-Declare the variables to be local whenever possible, especially loop control
- variables (induction).
-\layout Itemize
+\end_inset
+</cell>
+</row>
+<row topline="true">
+<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
+\begin_inset Text
-Since the compiler does not always do implicit integral promotion, the programme
-r should do an explicit cast when integral promotion is required.
-\layout Itemize
+\layout Standard
-Reducing the size of division, multiplication & modulus operations can reduce
- code size substantially.
- Take the following code for example.
-\begin_deeper
-\layout Verse
+c-faq
+\end_inset
+</cell>
+<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
+\begin_inset Text
+\layout Standard
+
+C-FAQ-list
+\end_inset
+</cell>
+<cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
+\begin_inset Text
-\family typewriter
-foobar(unsigned int p1, unsigned char ch)
-\newline
-{
-\newline
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-\SpecialChar ~
-\SpecialChar ~
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-\SpecialChar ~
-\SpecialChar ~
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-For the modulus operation the variable ch will be promoted to unsigned int
- first then the modulus operation will be performed (this will lead to a
- call to support routine _moduint()), and the result will be casted to a
- char.
- If the code is changed to
-\layout Verse
+\begin_inset LatexCommand \url{http://www.eskimo.com/~scs/C-faq/top.html}
+
+\end_inset
+
+
+\end_inset
+</cell>
+</row>
+<row topline="true">
+<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
+\begin_inset Text
-\family typewriter
-foobar(unsigned int p1, unsigned char ch)
-\newline
-{
-\newline
-\SpecialChar ~
-\SpecialChar ~
-\SpecialChar ~
-\SpecialChar ~
-unsigned char ch1 = (unsigned char)p1 % ch ;
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-\SpecialChar ~
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-\newline
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\layout Standard
-It would substantially reduce the code generated (future versions of the
- compiler will be smart enough to detect such optimization opportunities).
-\end_deeper
-\layout Itemize
+\end_inset
+</cell>
+<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
+\begin_inset Text
-Have a look at the assembly listing to get a
-\begin_inset Quotes sld
+\layout Standard
+
+Latest datasheet of the target CPU
\end_inset
+</cell>
+<cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
+\begin_inset Text
+
+\layout Standard
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+vendor
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+<row topline="true">
+<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
+\begin_inset Text
+
+\layout Standard
-feeling
-\begin_inset Quotes srd
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+<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
+\begin_inset Text
- for the code generation.
-\layout Section
+\layout Standard
-Notes on MCS51 memory
-\begin_inset LatexCommand \index{MCS51 memory}
+Revision history of datasheet
+\end_inset
+</cell>
+<cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
+\begin_inset Text
+
+\layout Standard
+vendor
\end_inset
+</cell>
+</row>
+<row topline="true" bottomline="true">
+<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
+\begin_inset Text
- layout
\layout Standard
-The 8051 family of microcontrollers have a minimum of 128 bytes of internal
- RAM memory which is structured as follows
-\newline
+S.
+ S.
+ Muchnick
+\end_inset
+</cell>
+<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
+\begin_inset Text
-\newline
-- Bytes 00-1F - 32 bytes to hold up to 4 banks of the registers R0 to R7,
-
-\newline
-- Bytes 20-2F - 16 bytes to hold 128 bit
-\begin_inset LatexCommand \index{bit}
+\layout Standard
+Advanced Compiler Design and Implementation
\end_inset
+</cell>
+<cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
+\begin_inset Text
+
+\layout Standard
+
+bookstore (very dedicated, probably read other books first)
+\end_inset
+</cell>
+</row>
+</lyxtabular>
+
+\end_inset
+
- variables and,
-\newline
-- Bytes 30-7F - 80 bytes for general purpose use.
\newline
+\layout Section
+
+Some Questions
\layout Standard
-Additionally some members of the MCS51 family may have up to 128 bytes of
- additional, indirectly addressable, internal RAM memory (
+Some questions answered, some pointers given - it might be time to in turn
+ ask
\emph on
-idata
+you
\emph default
+ some questions:
+\layout Itemize
-\begin_inset LatexCommand \index{idata}
+can you solve your project with the selected microcontroller? Would you
+ find out early or rather late that your target is too small/slow/whatever?
+ Can you switch to a slightly better device if it doesn't fit?
+\layout Itemize
-\end_inset
+should you solve the problem with an 8 bit CPU? Or would a 16/32 bit CPU
+ and/or another programming language be more adequate? Would an operating
+ system on the target device help?
+\layout Itemize
-).
- Furthermore, some chips may have some built in external memory (
-\emph on
-xdata
-\emph default
+if you solved the problem, will the marketing department be happy?
+\layout Itemize
-\begin_inset LatexCommand \index{xdata}
+if the marketing department is happy, will customers be happy?
+\layout Itemize
-\end_inset
+if you're the project manager, marketing department and maybe even the customer
+ in one person, have you tried to see the project from the outside?
+\layout Itemize
-) which should not be confused with the internal, directly addressable RAM
- memory (
+is the project done if you think it is done? Or is just that other interface/pro
+tocol/feature/configuration/option missing? How about website, manual(s),
+ internationali(z|s)ation, packaging, labels, 2nd source for components,
+ electromagnetic compatability/interference, documentation for production,
+ production test software, update mechanism, patent issues?
+\layout Itemize
+
+is your project adequately positioned in that magic triangle: fame, fortune,
+ fun?
+\layout Standard
+
+Maybe not all answers to these questions are known and some answers may
+ even be
\emph on
-data
+no
\emph default
+, nevertheless knowing these questions may help you to avoid burnout
+\begin_inset Foot
+collapsed false
-\begin_inset LatexCommand \index{data}
+\layout Standard
+burnout is bad for electronic devices, programmers and motorcycle tyres
\end_inset
-).
- Sometimes this built in
-\emph on
-xdata
-\emph default
- memory has to be activated before using it (you can probably find this
- information on the datasheet of the microcontroller your are using, see
- also section
-\begin_inset LatexCommand \ref{sub:Startup-Code}
+.
+ Chances are you didn't want to hear some of them...
+\layout Chapter
+
+Support
+\begin_inset LatexCommand \index{Support}
\end_inset
-\SpecialChar ~
-Startup-Code).
+
+\layout Standard
+
+SDCC has grown to be a large project.
+ The compiler alone (without the preprocessor, assembler and linker) is
+ well over 100,000 lines of code (blank stripped).
+ The open source nature of this project is a key to its continued growth
+ and support.
+ You gain the benefit and support of many active software developers and
+ end users.
+ Is SDCC perfect? No, that's why we need your help.
+ The developers take pride in fixing reported bugs.
+ You can help by reporting the bugs and helping other SDCC users.
+ There are lots of ways to contribute, and we encourage you to take part
+ in making SDCC a great software package.
+
\layout Standard
-Normally SDCC will only use the first bank
-\begin_inset LatexCommand \index{bank}
+The SDCC project is hosted on the SDCC sourceforge site at
+\begin_inset LatexCommand \htmlurl{http://sourceforge.net/projects/sdcc}
+
+\end_inset
+
+.
+ You'll find the complete set of mailing lists
+\begin_inset LatexCommand \index{Mailing list(s)}
+
+\end_inset
+
+, forums, bug reporting system, patch submission
+\begin_inset LatexCommand \index{Patch submission}
\end_inset
- of registers (register bank 0), but it is possible to specify that other
- banks of registers should be used in interrupt
-\begin_inset LatexCommand \index{interrupt}
+ system, download
+\begin_inset LatexCommand \index{download}
\end_inset
- routines.
- By default, the compiler will place the stack after the last byte of allocated
- memory for variables.
- For example, if the first 2 banks of registers are used, and only four
- bytes are used for
-\emph on
-data
-\emph default
- variables, it will position the base of the internal stack at address 20
- (0x14).
- This implies that as the stack
-\begin_inset LatexCommand \index{stack}
+ area and Subversion code repository
+\begin_inset LatexCommand \index{Subversion code repository}
\end_inset
- grows, it will use up the remaining register banks, and the 16 bytes used
- by the 128 bit variables, and 80 bytes for general purpose use.
- If any bit variables are used, the data variables will be placed after
- the byte holding the last bit variable.
- For example, if register banks 0 and 1 are used, and there are 9 bit variables
- (two bytes used),
-\emph on
-data
-\emph default
- variables will be placed starting at address 0x22.
- You can also use -
-\begin_inset ERT
-status Collapsed
+ there.
+\layout Section
-\layout Standard
+Reporting Bugs
+\begin_inset LatexCommand \index{Bug reporting}
-\backslash
-/
\end_inset
--data-loc
-\begin_inset LatexCommand \index{-\/-data-loc}
+
+\begin_inset LatexCommand \index{Reporting bugs}
\end_inset
- to specify the start address of the
-\emph on
-data
-\emph default
- and -
-\begin_inset ERT
-status Collapsed
\layout Standard
-\backslash
-/
-\end_inset
-
--iram-size to specify the size of the total internal RAM (
-\emph on
-data
-\emph default
-+
-\emph on
-idata
-\emph default
-).
-
+The recommended way of reporting bugs is using the infrastructure of the
+ sourceforge site.
+ You can follow the status of bug reports there and have an overview about
+ the known bugs.
\layout Standard
-By default the 8051 linker will place the stack after the last byte of data
- variables.
- Option -
+Bug reports are automatically forwarded to the developer mailing list and
+ will be fixed ASAP.
+ When reporting a bug, it is very useful to include a small test program
+ (the smaller the better) which reproduces the problem.
+ If you can isolate the problem by looking at the generated assembly code,
+ this can be very helpful.
+ Compiling your program with the -
\begin_inset ERT
status Collapsed
/
\end_inset
--stack-loc
-\begin_inset LatexCommand \index{-\/-stack-loc}
+-dumpall
+\begin_inset LatexCommand \index{-\/-dumpall}
\end_inset
- allows you to specify the start of the stack, i.e.
- you could start it after any data in the general purpose area.
- If your microcontroller has additional indirectly addressable internal
- RAM (
-\emph on
-idata
-\emph default
-) you can place the stack on it.
- You may also need to use -
-\begin_inset ERT
-status Collapsed
+ option can sometimes be useful in locating optimization problems.
+ When reporting a bug please maker sure you:
+\layout Enumerate
-\layout Standard
+Attach the code you are compiling with SDCC.
+
+\layout Enumerate
-\backslash
-/
-\end_inset
+Specify the exact command you use to run SDCC, or attach your Makefile.
+
+\layout Enumerate
--xdata-loc
-\begin_inset LatexCommand \index{-\/-data-loc}
+Specify the SDCC version (type "
+\family sans
+\series bold
+sdcc -v
+\family default
+\series default
+"), your platform, and operating system.
+
+\layout Enumerate
-\end_inset
+Provide an exact copy of any error message or incorrect output.
+
+\layout Enumerate
- to set the start address of the external RAM (
-\emph on
-xdata
-\emph default
-) and -
-\begin_inset ERT
-status Collapsed
+Put something meaningful in the subject of your message.
+\layout Standard
+Please attempt to include these 5 important parts, as applicable, in all
+ requests for support or when reporting any problems or bugs with SDCC.
+ Though this will make your message lengthy, it will greatly improve your
+ chance that SDCC users and developers will be able to help you.
+ Some SDCC developers are frustrated by bug reports without code provided
+ that they can use to reproduce and ultimately fix the problem, so please
+ be sure to provide sample code if you are reporting a bug!
\layout Standard
-\backslash
-/
+Please have a short check that you are using a recent version of SDCC and
+ the bug is not yet known.
+ This is the link for reporting bugs:
+\begin_inset LatexCommand \htmlurl{http://sourceforge.net/tracker/?group_id=599&atid=100599}
+
\end_inset
--xram-size
-\begin_inset LatexCommand \index{-\/-data-loc}
+.
+\layout Section
+
+Requesting Features
+\begin_inset LatexCommand \label{sub:Requesting-Features}
\end_inset
- to specify its size.
- Same goes for the code memory, using -
-\begin_inset ERT
-status Collapsed
-\layout Standard
+\begin_inset LatexCommand \index{Feature request}
-\backslash
-/
\end_inset
--code-loc
-\begin_inset LatexCommand \index{-\/-data-loc}
+
+\begin_inset LatexCommand \index{Requesting features}
\end_inset
- and -
-\begin_inset ERT
-status Collapsed
\layout Standard
-\backslash
-/
-\end_inset
-
--code-size
-\begin_inset LatexCommand \index{-\/-data-loc}
+Like bug reports feature requests are forwarded to the developer mailing
+ list.
+ This is the link for requesting features:
+\begin_inset LatexCommand \htmlurl{http://sourceforge.net/tracker/?group_id=599&atid=350599}
\end_inset
.
- If in doubt, don't specify any options and see if the resulting memory
- layout is appropriate, then you can adjust it.
-\layout Standard
-
-The 8051 linker generates two files with memory allocation information.
- The first, with extension .map shows all the variables and segments.
- The second with extension .mem shows the final memory layout.
- The linker will complaint either if memory segments overlap, there is not
- enough memory, or there is not enough space for stack.
- If you get any linking warnings and/or errors related to stack or segments
- allocation, take a look at either the .map or .mem files to find out what
- the problem is.
- The .mem file may even suggest a solution to the problem.
\layout Section
-Tools
-\begin_inset LatexCommand \index{Tools}
+Submitting patches
+\layout Standard
+
+Like bug reports contributed patches are forwarded to the developer mailing
+ list.
+ This is the link for submitting patches
+\begin_inset LatexCommand \index{Patch submission}
\end_inset
- included in the distribution
-\layout Standard
-\align center
+:
+\begin_inset LatexCommand \url{http://sourceforge.net/tracker/?group_id=599&atid=300599}
-\begin_inset Tabular
-<lyxtabular version="3" rows="12" columns="3">
-<features>
-<column alignment="center" valignment="top" leftline="true" width="0pt">
-<column alignment="center" valignment="top" leftline="true" width="0pt">
-<column alignment="center" valignment="top" leftline="true" rightline="true" width="0pt">
-<row topline="true" bottomline="true">
-<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
-\begin_inset Text
+\end_inset
+.
\layout Standard
-Name
-\end_inset
-</cell>
-<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
-\begin_inset Text
+You need to specify some parameters to the
+\family typewriter
+diff
+\family default
+ command for the patches to be useful.
+ If you modified more than one file a patch created f.e.
+ with
+\family sans
+\series bold
-\layout Standard
+\begin_inset Quotes sld
+\end_inset
-Purpose
+diff -Naur unmodified_directory modified_directory >my_changes.patch
+\begin_inset Quotes srd
\end_inset
-</cell>
-<cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
-\begin_inset Text
-\layout Standard
-Directory
-\end_inset
-</cell>
-</row>
-<row topline="true">
-<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
-\begin_inset Text
+\family default
+\series default
+ will be fine, otherwise
+\family sans
+\series bold
-\layout Standard
+\begin_inset Quotes sld
+\end_inset
-uCsim
+diff -u sourcefile.c.orig sourcefile.c >my_changes.patch
+\begin_inset Quotes srd
\end_inset
-</cell>
-<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
-\begin_inset Text
-\layout Standard
-Simulator for various architectures
-\end_inset
-</cell>
-<cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
-\begin_inset Text
+\series default
+
+\family default
+will do.
+\layout Section
+Getting Help
\layout Standard
-sdcc/sim/ucsim
+These links should take you directly to the
+\begin_inset LatexCommand \url[Mailing lists]{http://sourceforge.net/mail/?group_id=599}
+
\end_inset
-</cell>
-</row>
-<row topline="true">
-<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
-\begin_inset Text
-\layout Standard
-keil2sdcc.pl
-\end_inset
-</cell>
-<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
-\begin_inset Text
+\begin_inset Foot
+collapsed false
\layout Standard
-header file conversion
+Traffic on sdcc-devel and sdcc-user is about 100 mails/month each not counting
+ automated messages (mid 2003)
\end_inset
-</cell>
-<cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
-\begin_inset Text
-\layout Standard
+ and the
+\begin_inset LatexCommand \url[Forums]{http://sourceforge.net/forum/?group_id=599}
-sdcc/support/scripts
\end_inset
-</cell>
-</row>
-<row topline="true">
-<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
-\begin_inset Text
-\layout Standard
+, lists
+\begin_inset LatexCommand \index{Mailing list(s)}
-mh2h.c
\end_inset
-</cell>
-<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
-\begin_inset Text
+ and forums are archived and searchable so if you are lucky someone already
+ had a similar problem.
+ While mails to the lists themselves are delivered promptly their web front
+ end on sourceforge sometimes shows a severe time lag (up to several weeks),
+ if you're seriously using SDCC please consider subscribing to the lists.
+\layout Section
+
+ChangeLog
\layout Standard
-header file conversion
+You can follow the status of the Subversion version
+\begin_inset LatexCommand \index{version}
+
\end_inset
-</cell>
-<cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
-\begin_inset Text
-\layout Standard
+ of SDCC by watching the Changelog
+\begin_inset LatexCommand \index{Changelog}
-sdcc/support/scripts
\end_inset
-</cell>
-</row>
-<row topline="true">
-<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
-\begin_inset Text
-\layout Standard
+ in the Subversion repository
+\newline
-as-gbz80
-\end_inset
-</cell>
-<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
-\begin_inset Text
+\size footnotesize
-\layout Standard
+\begin_inset LatexCommand \htmlurl{http://svn.sourceforge.net/viewcvs.cgi/*checkout*/sdcc/trunk/sdcc/ChangeLog}
-Assembler
\end_inset
-</cell>
-<cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
-\begin_inset Text
-\layout Standard
+.
+\layout Section
+Release policy
+\begin_inset LatexCommand \index{Release policy}
-\family roman
-\series medium
-\shape up
-\size normal
-\emph off
-\bar no
-\noun off
-\color none
-sdcc/bin
\end_inset
-</cell>
-</row>
-<row topline="true">
-<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
-\begin_inset Text
+
\layout Standard
-as-z80
+Historically there often were long delays between official releases and
+ the sourceforge download area tends to get not updated at all.
+ Excuses in the past might have referred to problems with live range analysis,
+ but as this was fixed a while ago, the current problem is that another
+ excuse has to be found.
+ Kidding aside, we have to get better there! On the other hand there are
+ daily snapshots available at
+\begin_inset LatexCommand \htmlurl[snap]{http://sdcc.sourceforge.net/snap.php}
+
\end_inset
-</cell>
-<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
-\begin_inset Text
-\layout Standard
+, and you can always build the very last version (hopefully with many bugs
+ fixed, and features added) from the source code available at
+\begin_inset LatexCommand \htmlurl[Source]{http://sdcc.sourceforge.net/snap.php#Source}
-Assembler
\end_inset
-</cell>
-<cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
-\begin_inset Text
-\layout Standard
+.
+\layout Section
+Examples
+\begin_inset LatexCommand \index{Examples}
-\family roman
-\series medium
-\shape up
-\size normal
-\emph off
-\bar no
-\noun off
-\color none
-sdcc/bin
\end_inset
-</cell>
-</row>
-<row topline="true">
-<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
-\begin_inset Text
+
\layout Standard
-asx8051
+You'll find some small examples in the directory
+\emph on
+sdcc/device/examples/.
+
+\emph default
+More examples and libraries are available at
+\emph on
+ The SDCC Open Knowledge Resource
+\begin_inset LatexCommand \url{http://sdccokr.dl9sec.de/}
+
\end_inset
-</cell>
-<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
-\begin_inset Text
-\layout Standard
+
+\emph default
+web site or at
+\begin_inset LatexCommand \url{http://www.pjrc.com/tech/8051/}
-Assembler
\end_inset
-</cell>
-<cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
-\begin_inset Text
-\layout Standard
+.
+\layout Comment
+I did insert a reference to Paul's web site here although it seems rather
+ dedicated to a specific 8032 board (I think it's okay because it f.e.
+ shows LCD/Harddisc interface and has a free 8051 monitor.
+ Independent 8032 board vendors face hard competition of heavily subsidized
+ development boards anyway).
+\layout Comment
+
+Maybe we should include some links to real world applications.
+ Preferably pointer to pointers (one for each architecture) so this stays
+ manageable here?
+\layout Section
+
+Quality control
+\begin_inset LatexCommand \index{Quality control}
-\family roman
-\series medium
-\shape up
-\size normal
-\emph off
-\bar no
-\noun off
-\color none
-sdcc/bin
\end_inset
-</cell>
-</row>
-<row topline="true">
-<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
-\begin_inset Text
+
\layout Standard
-sdcdb
+The compiler is passed through nightly compile and build checks.
+ The so called
+\shape italic
+regression tests
+\shape default
+
+\begin_inset LatexCommand \index{Regression test}
+
\end_inset
-</cell>
-<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
-\begin_inset Text
-\layout Standard
+ check that SDCC itself compiles flawlessly on several platforms and checks
+ the quality of the code generated by SDCC by running the code through simulator
+s.
+ There is a separate document
+\shape italic
+test_suite.pdf
+\begin_inset LatexCommand \index{Test suite}
-Simulator
\end_inset
-</cell>
-<cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
-\begin_inset Text
+
+\shape default
+ about this.
\layout Standard
+You'll find the test code in the directory
+\shape italic
+sdcc/support/regression
+\shape default
+.
+ You can run these tests manually by running
+\family sans
+make
+\family default
+ in this directory (or f.e.
+
+\family sans
+\series bold
-\family roman
-\series medium
-\shape up
-\size normal
-\emph off
-\bar no
-\noun off
-\color none
-sdcc/bin
+\begin_inset Quotes sld
\end_inset
-</cell>
-</row>
-<row topline="true">
-<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
-\begin_inset Text
-
-\layout Standard
-aslink
+make test-mcs51
+\begin_inset Quotes srd
\end_inset
-</cell>
-<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
-\begin_inset Text
-\layout Standard
-Linker
-\end_inset
-</cell>
-<cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
-\begin_inset Text
+\family default
+\series default
+ if you don't want to run the complete tests).
+ The test code might also be interesting if you want to look for examples
+\begin_inset LatexCommand \index{Examples}
-\layout Standard
+\end_inset
+ checking corner cases of SDCC or if you plan to submit patches
+\begin_inset LatexCommand \index{Patch submission}
-\family roman
-\series medium
-\shape up
-\size normal
-\emph off
-\bar no
-\noun off
-\color none
-sdcc/bin
\end_inset
-</cell>
-</row>
-<row topline="true">
-<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
-\begin_inset Text
+.
+\layout Standard
+
+The pic port uses a different set of regression tests, you'll find them
+ in the directory
+\shape italic
+sdcc/src/regression
+\shape default
+.
+\layout Section
+
+Use of SDCC in Education
\layout Standard
-link-z80
-\end_inset
-</cell>
-<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
-\begin_inset Text
+In short:
+\emph on
+highly
+\emph default
+ encouraged
+\begin_inset Foot
+collapsed false
\layout Standard
-Linker
+the phrase "use in education" might evoke the association "
+\emph on
+only
+\emph default
+ fit for use in education".
+ This connotation is not intended but nevertheless risked as the licensing
+ of SDCC makes it difficult to offer educational discounts
\end_inset
-</cell>
-<cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
-\begin_inset Text
-\layout Standard
+.
+ If your rationales are to:
+\layout Enumerate
+give students a chance to understand the
+\emph on
+complete
+\emph default
+ steps of code generation
+\layout Enumerate
+
+have a curriculum that can be extended for years.
+ Then you could use an fpga board as target and your curriculum will seamlessly
+ extend from logic synthesis (
+\begin_inset LatexCommand \url[http://www.opencores.org]{opencores.org}
-\family roman
-\series medium
-\shape up
-\size normal
-\emph off
-\bar no
-\noun off
-\color none
-sdcc/bin
\end_inset
-</cell>
-</row>
-<row topline="true">
-<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
-\begin_inset Text
-\layout Standard
+,
+\begin_inset LatexCommand \url[Oregano]{http://www.oregano.at/ip/ip01.htm}
-link-gbz80
\end_inset
-</cell>
-<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
-\begin_inset Text
-\layout Standard
+), over assembly programming, to C to FPGA compilers (
+\begin_inset LatexCommand \url[FPGAC]{http://sf.net/projects/fpgac}
-Linker
\end_inset
-</cell>
-<cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
-\begin_inset Text
-\layout Standard
+) and to C.
+\layout Enumerate
+be able to insert excursions about skills like using a revision control
+ system, submitting/applying patches, using a type-setting (as opposed to
+ word-processing) engine LyX/LaTeX, using
+\begin_inset LatexCommand \url[SourceForge]{http://www.sf.net}
-\family roman
-\series medium
-\shape up
-\size normal
-\emph off
-\bar no
-\noun off
-\color none
-sdcc/bin
\end_inset
-</cell>
-</row>
-<row topline="true" bottomline="true">
-<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
-\begin_inset Text
-\layout Standard
+, following some
+\begin_inset LatexCommand \url[netiquette]{http://en.wikipedia.org/wiki/Netiquette}
-packihx
\end_inset
-</cell>
-<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
-\begin_inset Text
-\layout Standard
+, understanding BSD/LGPL/GPL/Proprietary licensing, growth models of Open
+ Source Software, CPU simulation, compiler regression tests
+\begin_inset LatexCommand \index{Regression test}
-ihx packer
\end_inset
-</cell>
-<cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
-\begin_inset Text
-
-\layout Standard
+.
+
+\newline
+And if there should be a shortage of ideas then you can always point students
+ to the ever-growing feature request list
+\begin_inset LatexCommand \htmlurl{http://sourceforge.net/tracker/?group_id=599&atid=350599}
-\family roman
-\series medium
-\shape up
-\size normal
-\emph off
-\bar no
-\noun off
-\color none
-sdcc/bin
\end_inset
-</cell>
-</row>
-</lyxtabular>
+
+.
+\layout Enumerate
+
+not tie students to a specific host platform and instead allow them to use
+ a host platform of
+\emph on
+their
+\emph default
+ choice (among them Alpha, i386, i386_64, MacOs, Mips, Sparc, Windows and
+ eventually
+\begin_inset LatexCommand \url[OLPC]{http://wiki.laptop.org/wiki/One_Laptop_per_Child}
\end_inset
+)
+\layout Enumerate
-\newline
+not encourage students to use illegal copies of educational software
+\layout Enumerate
-\layout Section
+be immune to licensing/availability/price changes of the chosen tool chain
+\layout Enumerate
-Related open source tools
-\begin_inset LatexCommand \index{Related tools}
+be able to change to a new target platform without having to adopt a new
+ tool chain
+\layout Enumerate
-\end_inset
+have complete control over and insight into the tool chain
+\layout Enumerate
+
+make your students aware about the pros and cons of open source software
+ development
+\layout Enumerate
+give back to the public as you are probably at least partially publically
+ funded
+\layout Enumerate
+give students a chance to publically prove their skills and to possibly
+ see a world wide impact
\layout Standard
-\align center
-\begin_inset Tabular
-<lyxtabular version="3" rows="8" columns="3">
-<features>
-<column alignment="center" valignment="top" leftline="true" width="0pt">
-<column alignment="block" valignment="top" leftline="true" width="30line%">
-<column alignment="center" valignment="top" leftline="true" rightline="true" width="0pt">
-<row topline="true" bottomline="true">
-<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
-\begin_inset Text
+then SDCC is probably among the first choices.
+ Well, probably SDCC might be the only choice.
+\layout Chapter
+\pagebreak_top
+SDCC Technical Data
+\layout Section
-\layout Standard
+Optimizations
+\begin_inset LatexCommand \index{Optimizations}
-Name
\end_inset
-</cell>
-<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
-\begin_inset Text
+
\layout Standard
-Purpose
+SDCC performs a host of standard optimizations in addition to some MCU specific
+ optimizations.
+
+\layout Subsection
+
+Sub-expression Elimination
+\begin_inset LatexCommand \index{Subexpression elimination}
+
\end_inset
-</cell>
-<cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
-\begin_inset Text
+
\layout Standard
-Where to get
-\end_inset
-</cell>
-</row>
-<row topline="true">
-<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
-\begin_inset Text
+The compiler does local and
+\emph on
+g
+\emph default
+lobal
+\emph on
+c
+\emph default
+ommon
+\emph on
+s
+\emph default
+ubexpression
+\emph on
+e
+\emph default
+limination, e.g.:
+\layout Verse
+
+\family typewriter
+i = x + y + 1;
+\newline
+j = x + y;
\layout Standard
-gpsim
-\begin_inset LatexCommand \index{gpsim}
+will be translated to
+\layout Verse
-\end_inset
+\family typewriter
+iTemp = x + y;
+\newline
+i = iTemp + 1;
+\newline
+j = iTemp;
+\layout Standard
-\end_inset
-</cell>
-<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
-\begin_inset Text
+Some subexpressions are not as obvious as the above example, e.g.:
+\layout Verse
+
+\family typewriter
+a->b[i].c = 10;
+\newline
+a->b[i].d = 11;
\layout Standard
-PIC simulator
-\end_inset
-</cell>
-<cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
-\begin_inset Text
+In this case the address arithmetic a->b[i] will be computed only once;
+ the equivalent code in C would be.
+\layout Verse
+
+\family typewriter
+iTemp = a->b[i];
+\newline
+iTemp.c = 10;
+\newline
+iTemp.d = 11;
\layout Standard
+The compiler will try to keep these temporary variables in registers.
+\layout Subsection
-\begin_inset LatexCommand \url{http://www.dattalo.com/gnupic/gpsim.html}
+Dead-Code Elimination
+\begin_inset LatexCommand \index{Dead-code elimination}
\end_inset
-\end_inset
-</cell>
-</row>
-<row topline="true">
-<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
-\begin_inset Text
+\layout Verse
+
+
+\family typewriter
+int global;
+\newline
+\newline
+void f () {
+\newline
+\SpecialChar ~
+\SpecialChar ~
+int i;
+\newline
+\SpecialChar ~
+\SpecialChar ~
+i = 1; \SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+/* dead store */
+\newline
+\SpecialChar ~
+\SpecialChar ~
+global = 1;\SpecialChar ~
+/* dead store */
+\newline
+\SpecialChar ~
+\SpecialChar ~
+global = 2;
+\newline
+\SpecialChar ~
+\SpecialChar ~
+return;
+\newline
+\SpecialChar ~
+\SpecialChar ~
+global = 3;\SpecialChar ~
+/* unreachable */
+\newline
+}
\layout Standard
-flP5
-\end_inset
-</cell>
-<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
-\begin_inset Text
-
-\layout Standard
+will be changed to
+\layout Verse
-PIC programmer
-\end_inset
-</cell>
-<cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
-\begin_inset Text
-\layout Standard
+\family typewriter
+int global;
+\newline
+\newline
+void f () {
+\newline
+\SpecialChar ~
+\SpecialChar ~
+global = 2;
+\newline
+}
+\layout Subsection
-\begin_inset LatexCommand \url{http://digilander.libero.it/fbradasc/FLP5.html}
+Copy-Propagation
+\begin_inset LatexCommand \index{Copy propagation}
\end_inset
-\end_inset
-</cell>
-</row>
-<row topline="true">
-<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
-\begin_inset Text
+\layout Verse
+
+\family typewriter
+int f() {
+\newline
+\SpecialChar ~
+\SpecialChar ~
+int i, j;
+\newline
+\SpecialChar ~
+\SpecialChar ~
+i = 10;
+\newline
+\SpecialChar ~
+\SpecialChar ~
+j = i;
+\newline
+\SpecialChar ~
+\SpecialChar ~
+return j;
+\newline
+}
\layout Standard
-srecord
-\begin_inset LatexCommand \index{srecord}
+will be changed to
+\layout Verse
-\end_inset
+\family typewriter
+int f() {
+\newline
+\SpecialChar ~
+\SpecialChar ~
+int i, j;
+\newline
+\SpecialChar ~
+\SpecialChar ~
+i = 10;
+\newline
+\SpecialChar ~
+\SpecialChar ~
+j = 10;
+\newline
+\SpecialChar ~
+\SpecialChar ~
+return 10;
+\newline
+}
+\layout Standard
-\end_inset
-</cell>
-<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
-\begin_inset Text
+Note: the dead stores created by this copy propagation will be eliminated
+ by dead-code elimination.
+\layout Subsection
-\layout Standard
+Loop Optimizations
+\begin_inset LatexCommand \index{Loop optimization}
-Object file conversion, checksumming, ...
\end_inset
-</cell>
-<cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
-\begin_inset Text
-
-\layout Standard
-\begin_inset LatexCommand \url{http://srecord.sourceforge.net/}
+\begin_inset LatexCommand \label{sub:Loop-Optimizations}
\end_inset
-\end_inset
-</cell>
-</row>
-<row topline="true">
-<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
-\begin_inset Text
-
\layout Standard
-objdump
-\begin_inset LatexCommand \index{objdump}
+Two types of loop optimizations are done by SDCC
+\emph on
+loop invariant
+\emph default
+ lifting and
+\emph on
+ strength reduction
+\emph default
+ of loop induction variables.
+ In addition to the strength reduction the optimizer marks the induction
+ variables and the register allocator tries to keep the induction variables
+ in registers for the duration of the loop.
+ Because of this preference of the register allocator
+\begin_inset LatexCommand \index{Register allocation}
\end_inset
+, loop induction optimization causes an increase in register pressure, which
+ may cause unwanted spilling of other temporary variables into the stack
+\begin_inset LatexCommand \index{stack}
\end_inset
-</cell>
-<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
-\begin_inset Text
-
-\layout Standard
-Object file conversion, ...
-\end_inset
-</cell>
-<cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
-\begin_inset Text
+ / data space.
+ The compiler will generate a warning message when it is forced to allocate
+ extra space either on the stack or data space.
+ If this extra space allocation is undesirable then induction optimization
+ can be eliminated either for the entire source file (with -
+\begin_inset ERT
+status Collapsed
\layout Standard
-Part of binutils (should be there anyway)
+\backslash
+/
\end_inset
-</cell>
-</row>
-<row topline="true">
-<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
-\begin_inset Text
-
-\layout Standard
-doxygen
-\begin_inset LatexCommand \index{doxygen}
+-noinduction option) or for a given function only using #pragma\SpecialChar ~
+noinduction
+\begin_inset LatexCommand \index{\#pragma noinduction}
\end_inset
+.
+\newline
-\end_inset
-</cell>
-<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
-\begin_inset Text
-
-\layout Standard
+\newline
+Loop Invariant:
+\layout Verse
-Source code documentation system
-\end_inset
-</cell>
-<cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
-\begin_inset Text
+\family typewriter
+for (i = 0 ; i < 100 ; i ++)
+\newline
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+f += k + l;
\layout Standard
+changed to
+\layout Verse
-\begin_inset LatexCommand \url{http://www.doxygen.org}
-
-\end_inset
-
-
-\end_inset
-</cell>
-</row>
-<row topline="true">
-<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
-\begin_inset Text
+\family typewriter
+itemp = k + l;
+\newline
+for (i = 0; i < 100; i++)
+\newline
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+f += itemp;
\layout Standard
-splint
-\begin_inset LatexCommand \index{splint}
-
-\end_inset
+As mentioned previously some loop invariants are not as apparent, all static
+ address computations are also moved out of the loop.
+\newline
+\newline
+Strength Reduction
+\begin_inset LatexCommand \index{Strength reduction}
\end_inset
-</cell>
-<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
-\begin_inset Text
-\layout Standard
+, this optimization substitutes an expression by a cheaper expression:
+\layout Verse
-Statically checks c sources
-\end_inset
-</cell>
-<cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
-\begin_inset Text
+\family typewriter
+for (i=0;i < 100; i++)
+\newline
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+ar[i*5] = i*3;
\layout Standard
+changed to
+\layout Verse
-\begin_inset LatexCommand \url{http://www.splint.org}
-
-\end_inset
-
-
-\end_inset
-</cell>
-</row>
-<row topline="true" bottomline="true">
-<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
-\begin_inset Text
+\family typewriter
+itemp1 = 0;
+\newline
+itemp2 = 0;
+\newline
+for (i=0;i< 100;i++) {
+\newline
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+ar[itemp1] = itemp2;
+\newline
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+itemp1 += 5;
+\newline
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+itemp2 += 3;
+\newline
+}
\layout Standard
-ddd
-\begin_inset LatexCommand \index{ddd}
-
-\end_inset
-
+The more expensive multiplication
+\begin_inset LatexCommand \index{Multiplication}
\end_inset
-</cell>
-<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
-\begin_inset Text
-\layout Standard
+ is changed to a less expensive addition.
+\layout Subsection
-Debugger, serves nicely as GUI to sdcdb
-\begin_inset LatexCommand \index{sdcdb}
+Loop Reversing
+\begin_inset LatexCommand \index{Loop reversing}
\end_inset
- (Unix only)
-\end_inset
-</cell>
-<cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
-\begin_inset Text
\layout Standard
-
-\begin_inset LatexCommand \url{http://www.gnu.org/software/ddd/}
-
-\end_inset
-
-
+This optimization is done to reduce the overhead of checking loop boundaries
+ for every iteration.
+ Some simple loops can be reversed and implemented using a
+\begin_inset Quotes eld
\end_inset
-</cell>
-</row>
-</lyxtabular>
+decrement and jump if not zero
+\begin_inset Quotes erd
\end_inset
+ instruction.
+ SDCC checks for the following criterion to determine if a loop is reversible
+ (note: more sophisticated compilers use data-dependency analysis to make
+ this determination, SDCC uses a more simple minded analysis).
+\layout Itemize
+The 'for' loop is of the form
\newline
-\layout Section
-
-Related documentation / recommended reading
-\layout Standard
-\align center
-
-\begin_inset Tabular
-<lyxtabular version="3" rows="5" columns="3">
-<features>
-<column alignment="center" valignment="top" leftline="true" width="0pt">
-<column alignment="block" valignment="top" leftline="true" width="30line%">
-<column alignment="center" valignment="top" leftline="true" rightline="true" width="0pt">
-<row topline="true" bottomline="true">
-<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
-\begin_inset Text
+\newline
-\layout Standard
+\family typewriter
+for(<symbol> = <expression>; <sym> [< | <=] <expression>; [<sym>++ | <sym>
+ += 1])
+\newline
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+<for body>
+\layout Itemize
-Name
+The <for body> does not contain
+\begin_inset Quotes eld
\end_inset
-</cell>
-<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
-\begin_inset Text
-
-\layout Standard
-Subject / Title
+continue
+\begin_inset Quotes erd
\end_inset
-</cell>
-<cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
-\begin_inset Text
-
-\layout Standard
-Where to get
+ or 'break
+\begin_inset Quotes erd
\end_inset
-</cell>
-</row>
-<row topline="true">
-<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
-\begin_inset Text
-\layout Standard
+.
+\layout Itemize
-S.
- S.
- Muchnick
-\end_inset
-</cell>
-<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
-\begin_inset Text
+All goto's are contained within the loop.
+\layout Itemize
-\layout Standard
+No function calls within the loop.
+\layout Itemize
-Advanced Compiler Design and Implementation
-\end_inset
-</cell>
-<cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
-\begin_inset Text
+The loop control variable <sym> is not assigned any value within the loop
+\layout Itemize
-\layout Standard
+The loop control variable does NOT participate in any arithmetic operation
+ within the loop.
+\layout Itemize
-bookstore
-\end_inset
-</cell>
-</row>
-<row topline="true">
-<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
-\begin_inset Text
+There are NO switch statements in the loop.
+\layout Subsection
+Algebraic Simplifications
\layout Standard
+SDCC does numerous algebraic simplifications, the following is a small sub-set
+ of these optimizations.
+\layout Verse
-\family roman
-\series medium
-\shape up
-\size normal
-\emph off
-\bar no
-\noun off
-\color none
-c-refcard.pdf
-\end_inset
-</cell>
-<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
-\begin_inset Text
+\family typewriter
+i = j + 0;\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+ /* changed to: */\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+ i = j;
+\newline
+i /= 2;\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+ /* changed to: */\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+ i >>= 1;
+\newline
+i = j - j;\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+ /* changed to: */\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+ i = 0;
+\newline
+i = j / 1;\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+ /* changed to: */\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+ i = j;
\layout Standard
-C Reference Card
-\begin_inset LatexCommand \index{C Reference card}
-
-\end_inset
+Note the subexpressions
+\begin_inset LatexCommand \index{Subexpression}
-, 2 pages
\end_inset
-</cell>
-<cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
-\begin_inset Text
-
-\layout Standard
+ given above are generally introduced by macro expansions or as a result
+ of copy/constant propagation.
+\layout Subsection
-\begin_inset LatexCommand \url{http://www.refcards.com/about/c.html}
+'switch' Statements
+\begin_inset LatexCommand \label{sub:'switch'-Statements}
\end_inset
-\end_inset
-</cell>
-</row>
-<row topline="true">
-<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
-\begin_inset Text
-
-\layout Standard
+\begin_inset LatexCommand \index{switch statement}
-test_suite_spec.pdf
\end_inset
-</cell>
-<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
-\begin_inset Text
+
\layout Standard
-sdcc regression test
-\begin_inset LatexCommand \index{Regression test}
+SDCC can optimize switch statements to jump tables
+\begin_inset LatexCommand \index{jump tables}
\end_inset
+.
+ It makes the decision based on an estimate of the generated code size.
+ SDCC is quite liberal in the requirements for jump table generation:
+\layout Itemize
-\end_inset
-</cell>
-<cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
-\begin_inset Text
+The labels need not be in order, and the starting number need not be one
+ or zero, the case labels are in numerical sequence or not too many case
+ labels are missing.
+\begin_deeper
+\layout Verse
-\layout Standard
-sdcc/doc
-\end_inset
-</cell>
-</row>
-<row topline="true" bottomline="true">
-<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
-\begin_inset Text
+\family typewriter
+switch(i) {\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
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+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+switch (i) {
+\newline
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+case 4: ...\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
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+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+case 0: ...
+
+\newline
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+case 5: ...\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
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+\SpecialChar ~
+\SpecialChar ~
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+\SpecialChar ~
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+\SpecialChar ~
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+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+case 1: ...
+
+\newline
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+case 3: ...\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
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+\SpecialChar ~
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+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\newline
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+case 6: ...\SpecialChar ~
+\SpecialChar ~
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+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+case 3: ...
+
+\newline
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+case 7: ...\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+case 4: ...
+
+\newline
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+case 8: ...\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+case 5: ...
+
+\newline
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+case 9: ...\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+case 6: ...
+
+\newline
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+case 10: ...\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+case 7: ...
+
+\newline
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+case 11: ...\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+case 8: ...
+
+\newline
+}\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+}
\layout Standard
+Both the above switch statements will be implemented using a jump-table.
+ The example to the right side is slightly more efficient as the check for
+ the lower boundary of the jump-table is not needed.
+\end_deeper
+\layout Itemize
-\family roman
-\series medium
-\shape up
-\size normal
-\emph off
-\bar no
-\noun off
-\color none
-cdbfileformat.pd
-\family default
-\series default
-\shape default
-\size default
-\emph default
-\bar default
-\noun default
-\color default
-f
-\end_inset
-</cell>
-<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
-\begin_inset Text
-
-\layout Standard
+The number of case labels is not larger than supported by the target architectur
+e.
+\layout Itemize
-sdcc internal documentation
-\end_inset
-</cell>
-<cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
-\begin_inset Text
+If the case labels are not in numerical sequence ('gaps' between cases)
+ SDCC checks whether a jump table with additionally inserted dummy cases
+ is still attractive.
+
+\layout Itemize
+If the starting number is not zero and a check for the lower boundary of
+ the jump-table can thus be eliminated SDCC might insert dummy cases 0,
+ ...
+ .
\layout Standard
-sdcc/doc
-\end_inset
-</cell>
-</row>
-</lyxtabular>
-
-\end_inset
+Switch statements which have large gaps in the numeric sequence or those
+ that have too many case labels can be split into more than one switch statement
+ for efficient code generation, e.g.:
+\layout Verse
+\family typewriter
+switch (i) {
\newline
-
-\layout Chapter
-\pagebreak_top
-Support
-\begin_inset LatexCommand \index{Support}
-
-\end_inset
-
-
-\layout Standard
-
-SDCC has grown to be a large project.
- The compiler alone (without the preprocessor, assembler and linker) is
- well over 100,000 lines of code (blank stripped).
- The open source nature of this project is a key to its continued growth
- and support.
- You gain the benefit and support of many active software developers and
- end users.
- Is SDCC perfect? No, that's why we need your help.
- The developers take pride in fixing reported bugs.
- You can help by reporting the bugs and helping other SDCC users.
- There are lots of ways to contribute, and we encourage you to take part
- in making SDCC a great software package.
+\SpecialChar ~
+\SpecialChar ~
+case 1: ...
+\newline
+\SpecialChar ~
+\SpecialChar ~
+case 2: ...
+
+\newline
+\SpecialChar ~
+\SpecialChar ~
+case 3: ...
+
+\newline
+\SpecialChar ~
+\SpecialChar ~
+case 4: ...
+
+\newline
+\SpecialChar ~
+\SpecialChar ~
+case 5: ...
+
+\newline
+\SpecialChar ~
+\SpecialChar ~
+case 6: ...
+
+\newline
+\SpecialChar ~
+\SpecialChar ~
+case 7: ...
+
+\newline
+\SpecialChar ~
+\SpecialChar ~
+case 101: ...
+
+\newline
+\SpecialChar ~
+\SpecialChar ~
+case 102: ...
+
+\newline
+\SpecialChar ~
+\SpecialChar ~
+case 103: ...
+
+\newline
+\SpecialChar ~
+\SpecialChar ~
+case 104: ...
+
+\newline
+\SpecialChar ~
+\SpecialChar ~
+case 105: ...
+
+\newline
+\SpecialChar ~
+\SpecialChar ~
+case 106: ...
+
+\newline
+\SpecialChar ~
+\SpecialChar ~
+case 107: ...
+
+\newline
+}
\layout Standard
-The SDCC project is hosted on the SDCC sourceforge site at
-\begin_inset LatexCommand \htmlurl{http://sourceforge.net/projects/sdcc}
-
-\end_inset
-
-.
- You'll find the complete set of mailing lists
-\begin_inset LatexCommand \index{Mailing list}
-
-\end_inset
-
-, forums, bug reporting system, patch submission
-\begin_inset LatexCommand \index{Patch submission}
-
-\end_inset
-
- system, download
-\begin_inset LatexCommand \index{download}
-
-\end_inset
-
- area and cvs code repository
-\begin_inset LatexCommand \index{cvs code repository}
-
-\end_inset
-
- there.
-\layout Section
-
-Reporting Bugs
-\begin_inset LatexCommand \index{Bug reporting}
-
-\end_inset
-
-
-\begin_inset LatexCommand \index{Reporting bugs}
-
-\end_inset
-
-
-\layout Standard
-
-The recommended way of reporting bugs is using the infrastructure of the
- sourceforge site.
- You can follow the status of bug reports there and have an overview about
- the known bugs.
-\layout Standard
+If the above switch statement is broken down into two switch statements
+\layout Verse
-Bug reports are automatically forwarded to the developer mailing list and
- will be fixed ASAP.
- When reporting a bug, it is very useful to include a small test program
- (the smaller the better) which reproduces the problem.
- If you can isolate the problem by looking at the generated assembly code,
- this can be very helpful.
- Compiling your program with the -
-\begin_inset ERT
-status Collapsed
+\family typewriter
+switch (i) {
+\newline
+\SpecialChar ~
+\SpecialChar ~
+case 1: ...
+
+\newline
+\SpecialChar ~
+\SpecialChar ~
+case 2: ...
+
+\newline
+\SpecialChar ~
+\SpecialChar ~
+case 3: ...
+
+\newline
+\SpecialChar ~
+\SpecialChar ~
+case 4: ...
+
+\newline
+\SpecialChar ~
+\SpecialChar ~
+case 5: ...
+
+\newline
+\SpecialChar ~
+\SpecialChar ~
+case 6: ...
+
+\newline
+\SpecialChar ~
+\SpecialChar ~
+case 7: ...
+
+\newline
+}
\layout Standard
-\backslash
-/
-\end_inset
-
--dumpall
-\begin_inset LatexCommand \index{-\/-dumpall}
-
-\end_inset
+and
+\layout Verse
- option can sometimes be useful in locating optimization problems.
- When reporting a bug please maker sure you:
-\layout Enumerate
-Attach the code you are compiling with SDCC.
+\family typewriter
+switch (i) {
+\newline
+\SpecialChar ~
+\SpecialChar ~
+case 101: ...
-\layout Enumerate
-
-Specify the exact command you use to run SDCC, or attach your Makefile.
+\newline
+\SpecialChar ~
+\SpecialChar ~
+case 102: ...
-\layout Enumerate
-
-Specify the SDCC version (type "sdcc -v"), your platform, and operating
- system.
+\newline
+\SpecialChar ~
+\SpecialChar ~
+case 103: ...
-\layout Enumerate
-
-Provide an exact copy of any error message or incorrect output.
+\newline
+\SpecialChar ~
+\SpecialChar ~
+case 104: ...
-\layout Enumerate
-
-Put something meaningful in the subject of your message.
+\newline
+\SpecialChar ~
+\SpecialChar ~
+case 105: ...
+
+\newline
+\SpecialChar ~
+\SpecialChar ~
+case 106: ...
+
+\newline
+\SpecialChar ~
+\SpecialChar ~
+case 107: ...
+
+\newline
+}
\layout Standard
-Please attempt to include these 5 important parts, as applicable, in all
- requests for support or when reporting any problems or bugs with SDCC.
- Though this will make your message lengthy, it will greatly improve your
- chance that SDCC users and developers will be able to help you.
- Some SDCC developers are frustrated by bug reports without code provided
- that they can use to reproduce and ultimately fix the problem, so please
- be sure to provide sample code if you are reporting a bug!
+then both the switch statements will be implemented using jump-tables whereas
+ the unmodified switch statement will not be.
+\layout Comment
+
+There might be reasons which SDCC cannot know about to either favour or
+ not favour jump tables.
+ If the target system has to be as quick for the last switch case as for
+ the first (pro jump table), or if the switch argument is known to be zero
+ in the majority of the cases (contra jump table).
\layout Standard
-Please have a short check that you are using a recent version of SDCC and
- the bug is not yet known.
- This is the link for reporting bugs:
-\begin_inset LatexCommand \htmlurl{http://sourceforge.net/tracker/?group_id=599&atid=100599}
+The pragma nojtbound
+\begin_inset LatexCommand \index{\#pragma nojtbound}
\end_inset
-.
-\layout Section
-
-Requesting Features
-\begin_inset LatexCommand \label{sub:Requesting-Features}
+ can be used to turn off checking the
+\emph on
+j
+\emph default
+ump
+\emph on
+t
+\emph default
+able
+\emph on
+bound
+\emph default
+aries.
+ It has no effect if a default label is supplied.
+ Use of this pragma is dangerous: if the switch
+\begin_inset LatexCommand \index{switch statement}
\end_inset
+ argument is not matched by a case statement the processor will happily
+ jump into Nirvana.
+\layout Subsection
-\begin_inset LatexCommand \index{Feature request}
+Bit-shifting Operations
+\begin_inset LatexCommand \index{Bit shifting}
\end_inset
+.
+\layout Standard
-\begin_inset LatexCommand \index{Requesting features}
-
-\end_inset
+Bit shifting is one of the most frequently used operation in embedded programmin
+g.
+ SDCC tries to implement bit-shift operations in the most efficient way
+ possible, e.g.:
+\layout Verse
+\family typewriter
+unsigned char i;
+\newline
+...
+
+\newline
+i >>= 4;
+\newline
+...
\layout Standard
-Like bug reports feature requests are forwarded to the developer mailing
- list.
- This is the link for requesting features:
-\begin_inset LatexCommand \htmlurl{http://sourceforge.net/tracker/?group_id=599&atid=350599}
-
-\end_inset
+generates the following code:
+\layout Verse
-.
-\layout Section
-Getting Help
+\family typewriter
+mov\SpecialChar ~
+ a,_i
+\newline
+swap a
+\newline
+anl\SpecialChar ~
+ a,#0x0f
+\newline
+mov\SpecialChar ~
+ _i,a
\layout Standard
-These links should take you directly to the
-\begin_inset LatexCommand \url[Mailing lists]{http://sourceforge.net/mail/?group_id=599}
+In general SDCC will never setup a loop if the shift count is known.
+ Another example:
+\layout Verse
-\end_inset
+\family typewriter
+unsigned int i;
+\newline
+...
+
+\newline
+i >>= 9;
+\newline
+...
+\layout Standard
-\begin_inset Foot
-collapsed false
+will generate:
+\layout Verse
-\layout Standard
-Traffic on sdcc-devel and sdcc-user is about 100 mails/month each not counting
- automated messages (mid 2003)
-\end_inset
+\family typewriter
+mov\SpecialChar ~
+\SpecialChar ~
+a,(_i + 1)
+\newline
+mov\SpecialChar ~
+\SpecialChar ~
+(_i + 1),#0x00
+\newline
+clr\SpecialChar ~
+\SpecialChar ~
+c
+\newline
+rrc\SpecialChar ~
+\SpecialChar ~
+a
+\newline
+mov\SpecialChar ~
+\SpecialChar ~
+_i,a
+\layout Subsection
- and the
-\begin_inset LatexCommand \url[Forums]{http://sourceforge.net/forum/?group_id=599}
+Bit-rotation
+\begin_inset LatexCommand \index{Bit rotation}
\end_inset
-, lists and forums are archived so if you are lucky someone already had
- a similar problem.
-\layout Section
-ChangeLog
-\begin_inset LatexCommand \index{Changelog}
+\layout Standard
+
+A special case of the bit-shift operation is bit rotation
+\begin_inset LatexCommand \index{rotating bits}
\end_inset
+, SDCC recognizes the following expression to be a left bit-rotation:
+\layout Verse
-\layout Standard
-You can follow the status of the cvs version
-\begin_inset LatexCommand \index{version}
+\family typewriter
+\series bold
+unsigned
+\series default
+\SpecialChar ~
+\SpecialChar ~
+char i;\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+/* unsigned is needed for rotation */
+\newline
+...
+
+\newline
+i = ((i << 1) | (i >> 7));
+\family default
-\end_inset
+\newline
+
+\family typewriter
+...
+\layout Standard
- of SDCC by watching the file
-\begin_inset LatexCommand \htmlurl[ChangeLog]{http://cvs.sourceforge.net/cgi-bin/viewcvs.cgi/*checkout*/sdcc/sdcc/ChangeLog?rev=HEAD&content-type=text/plain}
+will generate the following code:
+\layout Verse
-\end_inset
- in the cvs-repository.
-\layout Section
+\family typewriter
+mov\SpecialChar ~
+\SpecialChar ~
+a,_i
+\newline
+rl\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+a
+\newline
+mov\SpecialChar ~
+\SpecialChar ~
+_i,a
+\layout Standard
-Release policy
-\begin_inset LatexCommand \index{Release policy}
+SDCC uses pattern matching on the parse tree to determine this operation.Variatio
+ns of this case will also be recognized as bit-rotation, i.e.:
+\layout Verse
-\end_inset
+\family typewriter
+i = ((i >> 7) | (i << 1)); /* left-bit rotation */
+\layout Subsection
+Nibble and Byte Swapping
\layout Standard
-Historically there often were long delays between official releases and
- the sourceforge download area tends to get not updated at all.
- Current excuses might refer to problems with live range analysis, but if
- this is fixed, the next problem rising is that another excuse will have
- to be found.
- Kidding aside, we have to get better there! On the other hand there are
- daily snapshots available at
-\begin_inset LatexCommand \htmlurl[snap]{http://sdcc.sourceforge.net/snap.php}
+Other special cases of the bit-shift operations are nibble or byte swapping
+\begin_inset LatexCommand \index{swapping nibbles/bytes}
\end_inset
-, and you can always built the very last version (hopefully with many bugs
- fixed, and features added) from the source code available at
-\begin_inset LatexCommand \htmlurl[Source]{http://sdcc.sourceforge.net/snap.php#Source}
-
-\end_inset
+, SDCC recognizes the following expressions:
+\layout Verse
-.
-\layout Section
-Examples
-\begin_inset LatexCommand \index{Examples}
+\family typewriter
+\series bold
+unsigned
+\series default
+\SpecialChar ~
+\SpecialChar ~
+char i;
+\newline
-\end_inset
+\series bold
+unsigned
+\series default
+\SpecialChar ~
+\SpecialChar ~
+int j;
+\newline
+...
+
+\newline
+i = ((i << 4) | (i >> 4));
+\family default
+\newline
+\family typewriter
+j = ((j << 8) | (j >> 8));
\layout Standard
-You'll find some small examples in the directory
-\emph on
-sdcc/device/examples/.
-
-\emph default
-More examples and libraries are available at
-\emph on
- The SDCC Open Knowledge Resource
-\begin_inset LatexCommand \url{http://www.qsl.net/dl9sec/SDCC_OKR.html}
+and generates a swap instruction for the nibble swapping
+\begin_inset LatexCommand \index{Nibble swapping}
\end_inset
-
-\emph default
-web site or at
-\begin_inset LatexCommand \url{http://www.pjrc.com/tech/8051/}
+ or move instructions for the byte swapping
+\begin_inset LatexCommand \index{Byte swapping}
\end_inset
.
-\layout Comment
-
-I did insert a reference to Paul's web site here although it seems rather
- dedicated to a specific 8032 board (I think it's okay because it f.e.
- shows LCD/Harddisc interface and has a free 8051 monitor.
- Independent 8032 board vendors face hard competition of heavily subsidized
- development boards anyway).
-\layout Comment
-
-Maybe we should include some links to real world applications.
- Preferably pointer to pointers (one for each architecture) so this stays
- manageable here?
-\layout Section
-
-Quality control
-\begin_inset LatexCommand \index{Quality control}
-
+ The
+\begin_inset Quotes sld
\end_inset
+j
+\begin_inset Quotes srd
+\end_inset
+ example can be used to convert from little to big-endian or vice versa.
+ If you want to change the endianness of a
+\emph on
+signed
+\emph default
+ integer you have to cast to
+\family typewriter
+(unsigned int)
+\family default
+ first.
\layout Standard
-The compiler is passed through nightly compile and build checks.
- The so called
-\shape italic
-regression tests
-\shape default
+Note that SDCC stores numbers in little-endian
+\begin_inset Foot
+collapsed false
-\begin_inset LatexCommand \index{Regression test}
+\layout Standard
-\end_inset
+Usually 8-bit processors don't care much about endianness.
+ This is not the case for the standard 8051 which only has an instruction
+ to increment its
+\emph on
+dptr
+\emph default
- check that SDCC itself compiles flawlessly on several platforms and checks
- the quality of the code generated by SDCC by running the code through simulator
-s.
- There is a separate document
-\shape italic
-test_suite.pdf
-\begin_inset LatexCommand \index{Test suite}
+\begin_inset LatexCommand \index{DPTR}
\end_inset
-
-\shape default
- about this.
-\layout Standard
-
-You'll find the test code in the directory
-\shape italic
-sdcc/support/regression
-\shape default
-.
- You can run these tests manually by running
-\family sans
-make
-\family default
- in this directory (or f.e.
+-datapointer
+\emph on
-\family sans
-make test-mcs51
-\family default
- if you don't want to run the complete tests).
- The test code might also be interesting if you want to look for examples
-\begin_inset LatexCommand \index{Examples}
-
+\emph default
+so little-endian is the more efficient byte order.
\end_inset
- checking corner cases of SDCC or if you plan to submit patches
-\begin_inset LatexCommand \index{Patch submission}
-\end_inset
+\begin_inset LatexCommand \index{little-endian}
-.
-\layout Standard
+\end_inset
-The pic port uses a different set of regression tests, you'll find them
- in the directory
-\shape italic
-sdcc/src/regression
-\shape default
-.
-\layout Chapter
-\pagebreak_top
-SDCC Technical Data
-\layout Section
-Optimizations
-\begin_inset LatexCommand \index{Optimizations}
+\begin_inset LatexCommand \index{Endianness}
\end_inset
-
-\layout Standard
-
-SDCC performs a host of standard optimizations in addition to some MCU specific
- optimizations.
-
+ format (i.e.
+ lowest order first).
\layout Subsection
-Sub-expression Elimination
-\begin_inset LatexCommand \index{Subexpression elimination}
+Highest Order Bit
+\begin_inset LatexCommand \index{Highest Order Bit}
\end_inset
+ / Any Order Bit
+\begin_inset LatexCommand \index{Any Order Bit}
-\layout Standard
-
-The compiler does local and global common subexpression elimination, e.g.:
-
-\layout Verse
-
-
-\family typewriter
-i = x + y + 1;
-\newline
-j = x + y;
-\layout Standard
-
-will be translated to
-\layout Verse
+\end_inset
-\family typewriter
-iTemp = x + y;
-\newline
-i = iTemp + 1;
-\newline
-j = iTemp;
\layout Standard
-Some subexpressions are not as obvious as the above example, e.g.:
+It is frequently required to obtain the highest order bit of an integral
+ type (long, int, short or char types).
+ Also obtaining any other order bit is not uncommon.
+ SDCC recognizes the following expressions to yield the highest order bit
+ and generates optimized code for it, e.g.:
\layout Verse
\family typewriter
-a->b[i].c = 10;
+unsigned int gint;
\newline
-a->b[i].d = 11;
-\layout Standard
-
-In this case the address arithmetic a->b[i] will be computed only once;
- the equivalent code in C would be.
-\layout Verse
-
-\family typewriter
-iTemp = a->b[i];
-\newline
-iTemp.c = 10;
\newline
-iTemp.d = 11;
-\layout Standard
-
-The compiler will try to keep these temporary variables in registers.
-\layout Subsection
-
-Dead-Code Elimination
-\begin_inset LatexCommand \index{Dead-code elimination}
-
-\end_inset
-
-
-\layout Verse
-
-
-\family typewriter
-int global;
+foo () {
\newline
-
+\SpecialChar ~
+\SpecialChar ~
+unsigned char hob1, aob1;
\newline
-void f () {
+\SpecialChar ~
+\SpecialChar ~
+bit hob2, hob3, aob2, aob3;
\newline
\SpecialChar ~
\SpecialChar ~
-int i;
+...
+
\newline
\SpecialChar ~
\SpecialChar ~
-i = 1; \SpecialChar ~
+hob1 = (gint >> 15) & 1;
+\newline
\SpecialChar ~
\SpecialChar ~
+hob2 = (gint >> 15) & 1;
+\newline
\SpecialChar ~
\SpecialChar ~
-/* dead store */
+hob3 = gint & 0x8000;
\newline
\SpecialChar ~
\SpecialChar ~
-global = 1;\SpecialChar ~
-/* dead store */
+aob1 = (gint >> 9) & 1;
\newline
\SpecialChar ~
\SpecialChar ~
-global = 2;
+aob2 = (gint >> 8) & 1;
\newline
\SpecialChar ~
\SpecialChar ~
-return;
+aob3 = gint & 0x0800;
\newline
\SpecialChar ~
\SpecialChar ~
-global = 3;\SpecialChar ~
-/* unreachable */
+..
+
\newline
}
\layout Standard
-will be changed to
+will generate the following code:
\layout Verse
\family typewriter
-int global;
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+ 61 ;\SpecialChar ~
+ hob.c 7
\newline
-
+000A E5*01\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+ 62\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+ mov\SpecialChar ~
+\SpecialChar ~
+ a,(_gint + 1)
\newline
-void f () {
+000C 23\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+ 63\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+ rl\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+ a
+\newline
+000D 54 01\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+ 64\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+ anl\SpecialChar ~
+\SpecialChar ~
+ a,#0x01
+\newline
+000F F5*02\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+ 65\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+ mov\SpecialChar ~
+\SpecialChar ~
+ _foo_hob1_1_1,a
+\newline
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+ 66 ;\SpecialChar ~
+ hob.c 8
+\newline
+0011 E5*01\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+ 67\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+ mov\SpecialChar ~
+\SpecialChar ~
+ a,(_gint + 1)
+\newline
+0013 33\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+ 68\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+ rlc\SpecialChar ~
+\SpecialChar ~
+ a
\newline
+0014 92*00\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+ 69\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
\SpecialChar ~
\SpecialChar ~
-global = 2;
-\newline
\SpecialChar ~
+ mov\SpecialChar ~
\SpecialChar ~
-return;
-\newline
-}
-\layout Subsection
-
-Copy-Propagation
-\begin_inset LatexCommand \index{Copy propagation}
-
-\end_inset
-
-
-\layout Verse
-
-
-\family typewriter
-int f() {
+ _foo_hob2_1_1,c
\newline
\SpecialChar ~
\SpecialChar ~
-int i, j;
-\newline
\SpecialChar ~
\SpecialChar ~
-i = 10;
-\newline
\SpecialChar ~
\SpecialChar ~
-j = i;
-\newline
\SpecialChar ~
\SpecialChar ~
-return j;
-\newline
-}
-\layout Standard
-
-will be changed to
-\layout Verse
-
-
-\family typewriter
-int f() {
-\newline
\SpecialChar ~
\SpecialChar ~
-int i, j;
-\newline
\SpecialChar ~
\SpecialChar ~
-i = 10;
-\newline
\SpecialChar ~
\SpecialChar ~
-j = 10;
-\newline
\SpecialChar ~
\SpecialChar ~
-return 10;
-\newline
-}
-\layout Standard
-
-Note: the dead stores created by this copy propagation will be eliminated
- by dead-code elimination.
-\layout Subsection
-
-Loop Optimizations
-\begin_inset LatexCommand \index{Loop optimization}
-
-\end_inset
-
-
-\layout Standard
-
-Two types of loop optimizations are done by SDCC loop invariant lifting
- and strength reduction of loop induction variables.
- In addition to the strength reduction the optimizer marks the induction
- variables and the register allocator tries to keep the induction variables
- in registers for the duration of the loop.
- Because of this preference of the register allocator
-\begin_inset LatexCommand \index{Register allocation}
-
-\end_inset
-
-, loop induction optimization causes an increase in register pressure, which
- may cause unwanted spilling of other temporary variables into the stack
-\begin_inset LatexCommand \index{stack}
-
-\end_inset
-
- / data space.
- The compiler will generate a warning message when it is forced to allocate
- extra space either on the stack or data space.
- If this extra space allocation is undesirable then induction optimization
- can be eliminated either for the entire source file (with -
-\begin_inset ERT
-status Collapsed
-
-\layout Standard
-
-\backslash
-/
-\end_inset
-
--noinduction option) or for a given function only using #pragma\SpecialChar ~
-NOINDUCTION
-\begin_inset LatexCommand \index{\#pragma NOINDUCTION}
-
-\end_inset
-
-.
-\newline
-
-\newline
-Loop Invariant:
-\layout Verse
-
-
-\family typewriter
-for (i = 0 ; i < 100 ; i ++)
-\newline
\SpecialChar ~
\SpecialChar ~
\SpecialChar ~
\SpecialChar ~
-f += k + l;
-\layout Standard
-
-changed to
-\layout Verse
-
-
-\family typewriter
-itemp = k + l;
-\newline
-for (i = 0; i < 100; i++)
-\newline
\SpecialChar ~
\SpecialChar ~
\SpecialChar ~
\SpecialChar ~
-f += itemp;
-\layout Standard
-
-As mentioned previously some loop invariants are not as apparent, all static
- address computations are also moved out of the loop.
-\newline
-
-\newline
-Strength Reduction
-\begin_inset LatexCommand \index{Strength reduction}
-
-\end_inset
-
-, this optimization substitutes an expression by a cheaper expression:
-\layout Verse
-
-
-\family typewriter
-for (i=0;i < 100; i++)
+\SpecialChar ~
+ 66 ;\SpecialChar ~
+ hob.c 9
\newline
+0016 E5*01\SpecialChar ~
\SpecialChar ~
\SpecialChar ~
\SpecialChar ~
\SpecialChar ~
-ar[i*5] = i*3;
-\layout Standard
-
-changed to
-\layout Verse
-
-
-\family typewriter
-itemp1 = 0;
-\newline
-itemp2 = 0;
-\newline
-for (i=0;i< 100;i++) {
-\newline
\SpecialChar ~
\SpecialChar ~
\SpecialChar ~
\SpecialChar ~
-ar[itemp1] = itemp2;
-\newline
\SpecialChar ~
\SpecialChar ~
\SpecialChar ~
\SpecialChar ~
-itemp1 += 5;
-\newline
\SpecialChar ~
\SpecialChar ~
+ 67\SpecialChar ~
\SpecialChar ~
\SpecialChar ~
-itemp2 += 3;
-\newline
-}
-\layout Standard
-
-The more expensive multiplication
-\begin_inset LatexCommand \index{Multiplication}
-
-\end_inset
-
- is changed to a less expensive addition.
-\layout Subsection
-
-Loop Reversing
-\begin_inset LatexCommand \index{Loop reversing}
-
-\end_inset
-
-
-\layout Standard
-
-This optimization is done to reduce the overhead of checking loop boundaries
- for every iteration.
- Some simple loops can be reversed and implemented using a
-\begin_inset Quotes eld
-\end_inset
-
-decrement and jump if not zero
-\begin_inset Quotes erd
-\end_inset
-
- instruction.
- SDCC checks for the following criterion to determine if a loop is reversible
- (note: more sophisticated compilers use data-dependency analysis to make
- this determination, SDCC uses a more simple minded analysis).
-\layout Itemize
-
-The 'for' loop is of the form
-\newline
-
-\newline
-
-\family typewriter
-for(<symbol> = <expression>; <sym> [< | <=] <expression>; [<sym>++ | <sym>
- += 1])
-\newline
\SpecialChar ~
\SpecialChar ~
\SpecialChar ~
\SpecialChar ~
-<for body>
-\layout Itemize
-
-The <for body> does not contain
-\begin_inset Quotes eld
-\end_inset
-
-continue
-\begin_inset Quotes erd
-\end_inset
-
- or 'break
-\begin_inset Quotes erd
-\end_inset
-
-.
-\layout Itemize
-
-All goto's are contained within the loop.
-\layout Itemize
-
-No function calls within the loop.
-\layout Itemize
-
-The loop control variable <sym> is not assigned any value within the loop
-\layout Itemize
-
-The loop control variable does NOT participate in any arithmetic operation
- within the loop.
-\layout Itemize
-
-There are NO switch statements in the loop.
-\layout Subsection
-
-Algebraic Simplifications
-\layout Standard
-
-SDCC does numerous algebraic simplifications, the following is a small sub-set
- of these optimizations.
-\layout Verse
-
-
-\family typewriter
-i = j + 0 ; /* changed to */ i = j;
+\SpecialChar ~
+ mov\SpecialChar ~
+\SpecialChar ~
+ a,(_gint + 1)
\newline
-i /= 2;\SpecialChar ~
+0018 33\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
\SpecialChar ~
\SpecialChar ~
\SpecialChar ~
- /* changed to */ i >>= 1;
-\newline
-i = j - j ; /* changed to */ i = 0;
-\newline
-i = j / 1 ; /* changed to */ i = j;
-\layout Standard
-
-Note the subexpressions
-\begin_inset LatexCommand \index{Subexpression}
-
-\end_inset
-
- given above are generally introduced by macro expansions or as a result
- of copy/constant propagation.
-\layout Subsection
-
-'switch' Statements
-\begin_inset LatexCommand \label{sub:'switch'-Statements}
-
-\end_inset
-
-
-\begin_inset LatexCommand \index{switch statement}
-
-\end_inset
-
-
-\layout Standard
-
-SDCC changes switch statements to jump tables
-\begin_inset LatexCommand \index{jump tables}
-
-\end_inset
-
- when the following conditions are true.
-
-\layout Itemize
-
-The case labels are in numerical sequence, the labels need not be in order,
- and the starting number need not be one or zero.
-\begin_deeper
-\layout Verse
-
-
-\family typewriter
-switch(i) {\SpecialChar ~
\SpecialChar ~
\SpecialChar ~
\SpecialChar ~
\SpecialChar ~
\SpecialChar ~
+ 68\SpecialChar ~
\SpecialChar ~
\SpecialChar ~
\SpecialChar ~
\SpecialChar ~
\SpecialChar ~
\SpecialChar ~
+ rlc\SpecialChar ~
\SpecialChar ~
+ a
+\newline
+0019 92*01\SpecialChar ~
\SpecialChar ~
\SpecialChar ~
\SpecialChar ~
\SpecialChar ~
\SpecialChar ~
\SpecialChar ~
-switch (i) {
-\newline
\SpecialChar ~
\SpecialChar ~
+ 69\SpecialChar ~
\SpecialChar ~
-case 4: ...\SpecialChar ~
\SpecialChar ~
\SpecialChar ~
\SpecialChar ~
\SpecialChar ~
\SpecialChar ~
\SpecialChar ~
+ mov\SpecialChar ~
\SpecialChar ~
+ _foo_hob3_1_1,c
+\newline
\SpecialChar ~
\SpecialChar ~
\SpecialChar ~
\SpecialChar ~
\SpecialChar ~
\SpecialChar ~
-case 0: ...
-
-\newline
\SpecialChar ~
\SpecialChar ~
\SpecialChar ~
-case 5: ...\SpecialChar ~
\SpecialChar ~
\SpecialChar ~
\SpecialChar ~
\SpecialChar ~
+ 70 ;\SpecialChar ~
+ hob.c 10
+\newline
+001B E5*01\SpecialChar ~
\SpecialChar ~
\SpecialChar ~
\SpecialChar ~
\SpecialChar ~
\SpecialChar ~
\SpecialChar ~
+ 71\SpecialChar ~
\SpecialChar ~
\SpecialChar ~
\SpecialChar ~
\SpecialChar ~
\SpecialChar ~
\SpecialChar ~
-case 1: ...
-
+ mov\SpecialChar ~
+\SpecialChar ~
+ a,(_gint + 1)
\newline
+001D 03\SpecialChar ~
\SpecialChar ~
\SpecialChar ~
\SpecialChar ~
-case 3: ...\SpecialChar ~
\SpecialChar ~
\SpecialChar ~
\SpecialChar ~
\SpecialChar ~
\SpecialChar ~
\SpecialChar ~
+ 72\SpecialChar ~
\SpecialChar ~
\SpecialChar ~
\SpecialChar ~
\SpecialChar ~
\SpecialChar ~
\SpecialChar ~
+ rr\SpecialChar ~
\SpecialChar ~
\SpecialChar ~
+ a
+\newline
+001E 54 01\SpecialChar ~
\SpecialChar ~
\SpecialChar ~
-case 2: ...
-
-\newline
\SpecialChar ~
\SpecialChar ~
\SpecialChar ~
-case 6: ...\SpecialChar ~
\SpecialChar ~
\SpecialChar ~
\SpecialChar ~
\SpecialChar ~
\SpecialChar ~
\SpecialChar ~
+ 73\SpecialChar ~
\SpecialChar ~
\SpecialChar ~
\SpecialChar ~
\SpecialChar ~
\SpecialChar ~
\SpecialChar ~
+ anl\SpecialChar ~
\SpecialChar ~
+ a,#0x01
+\newline
+0020 F5*03\SpecialChar ~
\SpecialChar ~
\SpecialChar ~
\SpecialChar ~
\SpecialChar ~
\SpecialChar ~
\SpecialChar ~
-case 3: ...
-
-\newline
-}\SpecialChar ~
\SpecialChar ~
\SpecialChar ~
\SpecialChar ~
\SpecialChar ~
\SpecialChar ~
\SpecialChar ~
+ 74\SpecialChar ~
\SpecialChar ~
\SpecialChar ~
\SpecialChar ~
\SpecialChar ~
\SpecialChar ~
\SpecialChar ~
+ mov\SpecialChar ~
\SpecialChar ~
+ _foo_aob1_1_1,a
+\newline
\SpecialChar ~
\SpecialChar ~
\SpecialChar ~
\SpecialChar ~
\SpecialChar ~
\SpecialChar ~
-}
-\layout Standard
-
-Both the above switch statements will be implemented using a jump-table.
- The example to the right side is slightly more efficient as the check for
- the lower boundary of the jump-table is not needed.
-\end_deeper
-\layout Itemize
-
-The number of case labels is at least three, since it takes two conditional
- statements to handle the boundary conditions.
-\layout Itemize
-
-The number of case labels is less than 84, since each label takes 3 bytes
- and a jump-table can be utmost 256 bytes long.
-\layout Standard
-
-Switch statements which have gaps in the numeric sequence or those that
- have more that 84 case labels can be split into more than one switch statement
- for efficient code generation, e.g.:
-\layout Verse
-
-
-\family typewriter
-switch (i) {
-\newline
\SpecialChar ~
\SpecialChar ~
-case 1: ...
-
-\newline
\SpecialChar ~
\SpecialChar ~
-case 2: ...
-
+ 75 ;\SpecialChar ~
+ hob.c 11
\newline
+0022 E5*01\SpecialChar ~
\SpecialChar ~
\SpecialChar ~
-case 3: ...
-
-\newline
\SpecialChar ~
\SpecialChar ~
-case 4: ...
-
-\newline
\SpecialChar ~
\SpecialChar ~
-case 9: ...
-
-\newline
\SpecialChar ~
\SpecialChar ~
-case 10: ...
-
-\newline
\SpecialChar ~
\SpecialChar ~
-case 11: ...
-
-\newline
\SpecialChar ~
\SpecialChar ~
-case 12: ...
-
-\newline
-}
-\layout Standard
-
-If the above switch statement is broken down into two switch statements
-\layout Verse
-
-
-\family typewriter
-switch (i) {
-\newline
\SpecialChar ~
\SpecialChar ~
-case 1: ...
-
-\newline
+ 76\SpecialChar ~
\SpecialChar ~
\SpecialChar ~
-case 2: ...
-
-\newline
\SpecialChar ~
\SpecialChar ~
-case 3: ...
-
-\newline
\SpecialChar ~
\SpecialChar ~
-case 4: ...
-
-\newline
-}
-\layout Standard
-
-and
-\layout Verse
-
-
-\family typewriter
-switch (i) {
+\SpecialChar ~
+ mov\SpecialChar ~
+\SpecialChar ~
+ a,(_gint + 1)
\newline
+0024 13\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
\SpecialChar ~
\SpecialChar ~
-case 9:\SpecialChar ~
\SpecialChar ~
-...
-
-\newline
\SpecialChar ~
\SpecialChar ~
-case 10:\SpecialChar ~
-...
-
-\newline
\SpecialChar ~
\SpecialChar ~
-case 11:\SpecialChar ~
-...
-
-\newline
\SpecialChar ~
\SpecialChar ~
-case 12:\SpecialChar ~
-...
-
-\newline
-}
-\layout Standard
-
-then both the switch statements will be implemented using jump-tables whereas
- the unmodified switch statement will not be.
- You might also consider dummy cases 0 and 5 to 8 in this example.
-
-\newline
-The pragma NOJTBOUND
-\begin_inset LatexCommand \index{\#pragma NOJTBOUND}
-
-\end_inset
-
- can be used to turn off checking the
-\emph on
-j
-\emph default
-ump
-\emph on
-t
-\emph default
-able
-\emph on
-bound
-\emph default
-aries.
- It has no effect if a default label is supplied.
- Use of this pragma is dangerous: if the switch argument is not matched
- by a case statement the processor will happily jump into Nirvana.
-\layout Subsection
-
-Bit-shifting Operations
-\begin_inset LatexCommand \index{Bit shifting}
-
-\end_inset
-
-.
-\layout Standard
-
-Bit shifting is one of the most frequently used operation in embedded programmin
-g.
- SDCC tries to implement bit-shift operations in the most efficient way
- possible, e.g.:
-\layout Verse
-
-
-\family typewriter
-unsigned char i;
-\newline
-...
-
-\newline
-i >>= 4;
-\newline
-...
-\layout Standard
-
-generates the following code:
-\layout Verse
-
-
-\family typewriter
-mov\SpecialChar ~
- a,_i
-\newline
-swap a
-\newline
-anl\SpecialChar ~
- a,#0x0f
-\newline
-mov\SpecialChar ~
- _i,a
-\layout Standard
-
-In general SDCC will never setup a loop if the shift count is known.
- Another example:
-\layout Verse
-
-
-\family typewriter
-unsigned int i;
-\newline
-...
-
-\newline
-i >>= 9;
-\newline
-...
-\layout Standard
-
-will generate:
-\layout Verse
-
-
-\family typewriter
-mov\SpecialChar ~
\SpecialChar ~
-a,(_i + 1)
-\newline
-mov\SpecialChar ~
+ 77\SpecialChar ~
\SpecialChar ~
-(_i + 1),#0x00
-\newline
-clr\SpecialChar ~
\SpecialChar ~
-c
-\newline
-rrc\SpecialChar ~
\SpecialChar ~
-a
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+ rrc\SpecialChar ~
+\SpecialChar ~
+ a
\newline
-mov\SpecialChar ~
+0025 92*02\SpecialChar ~
\SpecialChar ~
-_i,a
-\layout Subsection
-
-Bit-rotation
-\begin_inset LatexCommand \index{Bit rotation}
-
-\end_inset
-
-
-\layout Standard
-
-A special case of the bit-shift operation is bit rotation
-\begin_inset LatexCommand \index{rotating bits}
-
-\end_inset
-
-, SDCC recognizes the following expression to be a left bit-rotation:
-\layout Verse
-
-
-\family typewriter
-\series bold
-unsigned
-\series default
\SpecialChar ~
\SpecialChar ~
-char i;\SpecialChar ~
\SpecialChar ~
\SpecialChar ~
\SpecialChar ~
\SpecialChar ~
\SpecialChar ~
\SpecialChar ~
-/* unsigned is needed for rotation */
-\newline
-...
-
-\newline
-i = ((i << 1) | (i >> 7));
-\family default
-
-\newline
-
-\family typewriter
-...
-\layout Standard
-
-will generate the following code:
-\layout Verse
-
-
-\family typewriter
-mov\SpecialChar ~
\SpecialChar ~
-a,_i
-\newline
-rl\SpecialChar ~
+ 78\SpecialChar ~
\SpecialChar ~
\SpecialChar ~
-a
-\newline
-mov\SpecialChar ~
\SpecialChar ~
-_i,a
-\layout Standard
-
-SDCC uses pattern matching on the parse tree to determine this operation.Variatio
-ns of this case will also be recognized as bit-rotation, i.e.:
-\layout Verse
-
-
-\family typewriter
-i = ((i >> 7) | (i << 1)); /* left-bit rotation */
-\layout Subsection
-
-Nibble and Byte Swapping
-\layout Standard
-
-Other special cases of the bit-shift operations are nibble or byte swapping
-\begin_inset LatexCommand \index{swapping nibbles/bytes}
-
-\end_inset
-
-, SDCC recognizes the following expressions:
-\layout Verse
-
-
-\family typewriter
-\series bold
-unsigned
-\series default
\SpecialChar ~
\SpecialChar ~
-char i;
+\SpecialChar ~
+\SpecialChar ~
+ mov\SpecialChar ~
+\SpecialChar ~
+ _foo_aob2_1_1,c
\newline
-
-\series bold
-unsigned
-\series default
\SpecialChar ~
\SpecialChar ~
-int j;
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+ 79 ;\SpecialChar ~
+ hob.c 12
\newline
-...
-
+0027 E5*01\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+ 80\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+ mov\SpecialChar ~
+\SpecialChar ~
+ a,(_gint + 1)
\newline
-i = ((i << 4) | (i >> 4));
-\family default
-
+0029 A2 E3\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+ 81\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+ mov\SpecialChar ~
+\SpecialChar ~
+ c,acc[3]
\newline
+002B 92*03\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+ 82\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+ mov\SpecialChar ~
+\SpecialChar ~
+ _foo_aob3_1_1,c
+\layout Standard
-\family typewriter
-j = ((j << 8) | (j >> 8));
-\layout Standard
-
-and generates a swap instruction for the nibble swapping
-\begin_inset LatexCommand \index{Nibble swapping}
-
-\end_inset
-
- or move instructions for the byte swapping
-\begin_inset LatexCommand \index{Byte swapping}
-
-\end_inset
-
-.
- The
-\begin_inset Quotes sld
-\end_inset
-
-j
-\begin_inset Quotes srd
-\end_inset
-
- example can be used to convert from little to big-endian or vice versa.
- If you want to change the endianness of a
-\emph on
-signed
-\emph default
- integer you have to cast to
-\family typewriter
-(unsigned int)
-\family default
- first.
-\layout Standard
-
-Note that SDCC stores numbers in little-endian
-\begin_inset Foot
-collapsed false
-
-\layout Standard
-
-Usually 8-bit processors don't care much about endianness.
- This is not the case for the standard 8051 which only has an instruction
- to increment its
-\emph on
-dptr
-\emph default
-
-\begin_inset LatexCommand \index{DPTR}
-
-\end_inset
-
--datapointer
+Other variations of these cases however will
\emph on
-
+not
\emph default
-so little-endian is the more efficient byte order.
-\end_inset
-
+ be recognized.
+ They are standard C expressions, so I heartily recommend these be the only
+ way to get the highest order bit, (it is portable).
+ Of course it will be recognized even if it is embedded in other expressions,
+ e.g.:
+\layout Verse
-\begin_inset LatexCommand \index{little-endian}
-\end_inset
+\family typewriter
+xyz = gint + ((gint >> 15) & 1);
+\layout Standard
+will still be recognized.
+\layout Subsection
-\begin_inset LatexCommand \index{Endianness}
+Higher Order Byte
+\begin_inset LatexCommand \index{Higher Order Byte}
\end_inset
- format (i.e.
- lowest order first).
-\layout Subsection
-
-Highest Order Bit
-\begin_inset LatexCommand \index{Highest Order Bit}
+ / Higher Order Word
+\begin_inset LatexCommand \index{Higher Order Word}
\end_inset
\layout Standard
-It is frequently required to obtain the highest order bit of an integral
- type (long, int, short or char types).
- SDCC recognizes the following expression to yield the highest order bit
- and generates optimized code for it, e.g.:
+It is also frequently required to obtain a higher order byte or word of
+ a larger integral type (long, int or short types).
+ SDCC recognizes the following expressions to yield the higher order byte
+ or word and generates optimized code for it, e.g.:
\layout Verse
\family typewriter
unsigned int gint;
\newline
+unsigned long int glong;
+\newline
\newline
foo () {
\newline
\SpecialChar ~
\SpecialChar ~
-unsigned char hob;
+unsigned char hob1, hob2;
+\newline
+\SpecialChar ~
+\SpecialChar ~
+unsigned int how1, how2;
\newline
\SpecialChar ~
\SpecialChar ~
\newline
\SpecialChar ~
\SpecialChar ~
-hob = (gint >> 15) & 1;
+hob1 = (gint >> 8) & 0xFF;
+\newline
+\SpecialChar ~
+\SpecialChar ~
+hob2 = glong >> 24;
+\newline
+\SpecialChar ~
+\SpecialChar ~
+how1 = (glong >> 16) & 0xFFFF;
+\newline
+\SpecialChar ~
+\SpecialChar ~
+how2 = glong >> 8;
\newline
\SpecialChar ~
\SpecialChar ~
\SpecialChar ~
\SpecialChar ~
\SpecialChar ~
- 61 ;\SpecialChar ~
- hob.c 7
+ 91 ;\SpecialChar ~
+ hob.c 15
\newline
-000A E5*01\SpecialChar ~
+0037 85*01*06\SpecialChar ~
\SpecialChar ~
\SpecialChar ~
\SpecialChar ~
\SpecialChar ~
\SpecialChar ~
\SpecialChar ~
+\SpecialChar ~
+ 92\SpecialChar ~
+\SpecialChar ~
\SpecialChar ~
\SpecialChar ~
\SpecialChar ~
\SpecialChar ~
- 62\SpecialChar ~
\SpecialChar ~
\SpecialChar ~
+ mov\SpecialChar ~
\SpecialChar ~
+ _foo_hob1_1_1,(_gint + 1)
+\newline
\SpecialChar ~
\SpecialChar ~
\SpecialChar ~
\SpecialChar ~
- mov\SpecialChar ~
\SpecialChar ~
- a,(_gint + 1)
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+ 93 ;\SpecialChar ~
+ hob.c 16
\newline
-000C 23\SpecialChar ~
+003A 85*05*07\SpecialChar ~
\SpecialChar ~
\SpecialChar ~
\SpecialChar ~
\SpecialChar ~
\SpecialChar ~
\SpecialChar ~
+ 94\SpecialChar ~
\SpecialChar ~
\SpecialChar ~
\SpecialChar ~
\SpecialChar ~
\SpecialChar ~
\SpecialChar ~
- 63\SpecialChar ~
\SpecialChar ~
+ mov\SpecialChar ~
+\SpecialChar ~
+ _foo_hob2_1_1,(_glong + 3)
+\newline
\SpecialChar ~
\SpecialChar ~
\SpecialChar ~
\SpecialChar ~
\SpecialChar ~
\SpecialChar ~
- rl\SpecialChar ~
\SpecialChar ~
\SpecialChar ~
- a
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+ 95 ;\SpecialChar ~
+ hob.c 17
\newline
-000D 54 01\SpecialChar ~
+003D 85*04*08\SpecialChar ~
\SpecialChar ~
\SpecialChar ~
\SpecialChar ~
\SpecialChar ~
\SpecialChar ~
\SpecialChar ~
+\SpecialChar ~
+ 96\SpecialChar ~
+\SpecialChar ~
\SpecialChar ~
\SpecialChar ~
\SpecialChar ~
\SpecialChar ~
- 64\SpecialChar ~
\SpecialChar ~
\SpecialChar ~
+ mov\SpecialChar ~
\SpecialChar ~
+ _foo_how1_1_1,(_glong + 2)
+\newline
+0040 85*05*09\SpecialChar ~
\SpecialChar ~
\SpecialChar ~
\SpecialChar ~
\SpecialChar ~
- anl\SpecialChar ~
\SpecialChar ~
- a,#0x01
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+ 97\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+ mov\SpecialChar ~
+\SpecialChar ~
+ (_foo_how1_1_1 + 1),(_glong + 3)
\newline
-000F F5*02\SpecialChar ~
+0043 85*03*0A\SpecialChar ~
\SpecialChar ~
\SpecialChar ~
\SpecialChar ~
\SpecialChar ~
\SpecialChar ~
\SpecialChar ~
+ 98\SpecialChar ~
\SpecialChar ~
\SpecialChar ~
\SpecialChar ~
- 65\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+ mov\SpecialChar ~
+\SpecialChar ~
+ _foo_how2_1_1,(_glong + 1)
+\newline
+0046 85*04*0B\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+ 99\SpecialChar ~
\SpecialChar ~
\SpecialChar ~
\SpecialChar ~
\SpecialChar ~
mov\SpecialChar ~
\SpecialChar ~
- _foo_hob_1_1,a
+ (_foo_how2_1_1 + 1),(_glong + 2)
\layout Standard
-Variations of this case however will
+Again, variations of these cases may
\emph on
not
\emph default
be recognized.
- It is a standard C expression, so I heartily recommend this be the only
- way to get the highest order bit, (it is portable).
+ They are standard C expressions, so I heartily recommend these be the only
+ way to get the higher order byte/word, (it is portable).
Of course it will be recognized even if it is embedded in other expressions,
e.g.:
\layout Verse
\family typewriter
-xyz = gint + ((gint >> 15) & 1);
+xyz = gint + ((gint >> 8) & 0xFF);
\layout Standard
will still be recognized.
copt
\emph default
a peep-hole optimizer by Christopher W.
- Fraser (cwfraser@microsoft.com).
+ Fraser (cwfraser\SpecialChar ~
+@\SpecialChar ~
+microsoft.com).
A default set of rules are compiled into the compiler, additional rules
may be added with the
\emph on
\emph default
).
E.g.
- some variants of the 8051 MCU allow only
+ some variants of the 8051 MCU
+\begin_inset LatexCommand \index{MCS51 variants}
+
+\end_inset
+
+ allow only
\family typewriter
ajmp
\family default
\layout Standard
Note that the replace pattern cannot be a blank, but can be a comment line.
- Without the 'restart' option only the inner most 'pop' 'push' pair would
+ Without the 'restart' option only the innermost 'pop' 'push' pair would
be eliminated, i.e.:
\layout Verse
labelInRange
\emph default
expects to find the label in that particular variable (the hash table containin
-g the variable bindings is passed as a parameter).
- If you want to code more such functions, take a close look at the function
- labelInRange and the calling mechanism in source file SDCCpeeph.c.
- Currently implemented are
-\emph on
-labelInRange, labelRefCount, labelIsReturnOnly, operandsNotSame, xramMovcOption,
- 24bitMode, portIsDS390, 24bitModeAndPortDS390
-\emph default
-and
-\emph on
- notVolatile
-\emph default
-.
-\layout Standard
-
-I know this whole thing is a little kludgey, but maybe some day we will
- have some better means.
- If you are looking at this file, you will see the default rules that are
- compiled into the compiler, you can add your own rules in the default set
- there if you get tired of specifying the -
-\begin_inset ERT
-status Collapsed
-
-\layout Standard
-
-\backslash
-/
-\end_inset
-
--peep-file option.
-\layout Section
-
-Library Routines
-\emph on
-
-\layout Standard
-
-
-\emph on
-<pending: this is messy and incomplete>
-\emph default
-
-\layout Enumerate
-
-Compiler support routines (_gptrget, _mulint etc)
-\layout Enumerate
-
-Stdclib functions (puts, printf, strcat etc)
-\layout Enumerate
-
-Math functions (sin, pow, sqrt etc)
-\layout Standard
-
-Libraries
-\begin_inset LatexCommand \index{Libraries}
-
-\end_inset
-
- included in SDCC should have a license at least as liberal as the GNU Lesser
- General Public License
-\begin_inset LatexCommand \index{GNU Lesser General Public License, LGPL}
-
-\end_inset
-
-
-\emph on
-LGPL
-\emph default
-.
-\layout Comment
-
-license statements for the libraries are missing.
- sdcc/device/lib/ser_ir.c
-\layout Comment
-
-or _decdptr f.e.
- come with a GPL (as opposed to LGPL) License - this will not be liberal
- enough for many embedded programmers.
-\layout Standard
-
-If you have ported some library or want to share experience about some code
- which f.e.
- falls into any of these categories Busses (I
-\begin_inset Formula $^{\textrm{2}}$
-\end_inset
-
-C, CAN, Ethernet, Profibus, Modbus, USB, SPI, JTAG ...), Media (IDE, Memory
- cards, eeprom, flash...), En-/Decryption, Remote debugging, Realtime kernel,
- Keyboard, LCD, RTC, FPGA, PID then the sdcc-user mailing list
-\begin_inset LatexCommand \url{http://sourceforge.net/mail/?group_id=599}
-
-\end_inset
-
-\SpecialChar ~
-would certainly like to hear about it.
- Programmers coding for embedded systems are not especially famous for being
- enthusiastic, so don't expect a big hurray but as the mailing list is searchabl
-e these references are very valuable.
-\layout Section
-
-External Stack
-\begin_inset LatexCommand \label{sub:External-Stack}
-
-\end_inset
-
-
-\begin_inset LatexCommand \index{stack}
-
-\end_inset
-
-
-\begin_inset LatexCommand \index{External stack}
-
-\end_inset
-
-
+g the variable bindings is passed as a parameter).
+ If you want to code more such functions, take a close look at the function
+ labelInRange and the calling mechanism in source file SDCCpeeph.c.
+ Currently implemented are
+\emph on
+labelInRange, labelRefCount, labelIsReturnOnly, operandsNotSame, xramMovcOption,
+ 24bitMode, portIsDS390, 24bitModeAndPortDS390
+\emph default
+and
+\emph on
+ notVolatile
+\emph default
+.
\layout Standard
-The external stack (-
+I know this whole thing is a little kludgey, but maybe some day we will
+ have some better means.
+ If you are looking at this file, you will see the default rules that are
+ compiled into the compiler, you can add your own rules in the default set
+ there if you get tired of specifying the -
\begin_inset ERT
status Collapsed
/
\end_inset
--xstack option
-\begin_inset LatexCommand \index{-\/-xstack}
+-peep-file option.
+\layout Section
+
+ANSI-Compliance
+\begin_inset LatexCommand \index{ANSI-compliance}
+
+\end_inset
+
+
+\begin_inset LatexCommand \label{sub:ANSI-Compliance}
\end_inset
-) is located at the start of the external ram segment, and is 256 bytes
- in size.
- When -
-\begin_inset ERT
-status Collapsed
\layout Standard
-\backslash
-/
+Deviations from the compliance:
+\layout Itemize
+
+functions are not reentrant
+\begin_inset LatexCommand \index{reentrant}
+
\end_inset
--xstack option is used to compile the program, the parameters and local
- variables of all reentrant functions are allocated in this area.
- This option is provided for programs with large stack space requirements.
- When used with the -
+ unless explicitly declared as such or the
+\series bold
+-
\begin_inset ERT
status Collapsed
\end_inset
- option, all parameters and local variables are allocated on the external
- stack (note support libraries will need to be recompiled with the same
- options).
-\layout Standard
-
-The compiler outputs the higher order address byte of the external ram segment
- into PORT P2, therefore when using the External Stack option, this port
- MAY NOT be used by the application program.
-\layout Section
-
-ANSI-Compliance
-\begin_inset LatexCommand \index{ANSI-compliance}
-
-\end_inset
-
-
-\begin_inset LatexCommand \label{sub:ANSI-Compliance}
-
-\end_inset
-
-
-\layout Standard
-
-Deviations from the compliance:
-\layout Itemize
-
-functions are not always reentrant
-\begin_inset LatexCommand \index{reentrant}
-
-\end_inset
-.
+\series default
+ command line option is specified.
\layout Itemize
-structures cannot be assigned values directly, cannot be passed as function
- parameters or assigned to each other and cannot be a return value from
- a function, e.g.:
+structures and unions cannot be assigned values directly, cannot be passed
+ as function parameters or assigned to each other and cannot be a return
+ value from a function, e.g.:
\begin_deeper
\layout Verse
\end_deeper
\layout Itemize
+initialization of structure arrays must be fully braced.
+\begin_deeper
+\layout Verse
+
+
+\family typewriter
+struct s { char x } a[] = {1, 2}; /* invalid in SDCC */
+\newline
+struct s { char x } a[] = {{1}, {2}}; /* OK */
+\end_deeper
+\layout Itemize
+
'long long
\begin_inset LatexCommand \index{long long (not supported)}
not supported.
\layout Itemize
-No support for setjmp
-\begin_inset LatexCommand \index{setjmp (not supported)}
-
-\end_inset
-
- and longjmp
-\begin_inset LatexCommand \index{longjmp (not supported)}
-
-\end_inset
-
- (for now).
-\layout Itemize
-
Old K&R style
\begin_inset LatexCommand \index{K\&R style}
\end_deeper
\layout Itemize
-functions declared as pointers
-\begin_inset LatexCommand \index{Pointers}
+Most enhancements in C99 are not supported, f.e.:
+\begin_deeper
+\layout Verse
+
+
+\family typewriter
+\series bold
+inline
+\series default
+ int increment (int a) { return a+1; } /* is invalid in SDCC although allowed
+ in C99 */
+\newline
+for (
+\series bold
+int
+\series default
+ i=0; i<10; i++) /* is invalid in SDCC although allowed in C99 */
+\end_deeper
+\layout Itemize
+
+Certain words that are valid identifiers in the standard may be reserved
+ words in SDCC unless the
+\series bold
+-
+\begin_inset ERT
+status Collapsed
+
+\layout Standard
+
+\backslash
+/
+\end_inset
+
+-std-c89
+\begin_inset LatexCommand \index{-\/-std-c89}
\end_inset
+ or -
+\begin_inset ERT
+status Collapsed
-\begin_inset LatexCommand \index{function pointers}
+\layout Standard
+\backslash
+/
\end_inset
- must be dereferenced during the call.
-\begin_deeper
-\layout Verse
+-std-c99
+\begin_inset LatexCommand \index{-\/-std-c99}
+\end_inset
-\family typewriter
-int (*foo)();
-\newline
-...
-
-\newline
-/* has to be called like this */
-\newline
-(*foo)(); /* ANSI standard allows calls to be made like 'foo()' */
-\end_deeper
+
+\series default
+ command line options are used.
+ These may include (depending on the selected processor): 'at', 'banked',
+ 'bit', 'code', 'critical', 'data', 'eeprom', 'far', 'flash', 'idata', 'interrup
+t', 'near', 'nonbanked', 'pdata', 'reentrant', 'sbit', 'sfr', 'shadowregs',
+ 'sram', 'using', 'wparam', 'xdata', '_overlay', '_asm', '_endasm', and
+ '_naked'.
+ Compliant equivalents of these keywords are always available in a form
+ that begin with two underscores
+\begin_inset LatexCommand \index{\_\_ (prefix for extended keywords)}
+
+\end_inset
+
+, f.e.
+ '__data' instead of 'data'.
\layout Section
Cyclomatic Complexity
for which functions you might look at for further optimization.
\layout Section
-Other Processors
-\layout Subsection
-
-MCS51 variants
-\begin_inset LatexCommand \label{sub:MCS51-variants}
-
-\end_inset
-
-
-\begin_inset LatexCommand \index{MCS51 variants}
-
-\end_inset
-
-
-\layout Standard
-
-MCS51 processors are available from many vendors and come in many different
- flavours.
- While they might differ considerably in respect to Special Function Registers
- the core MCS51 is usually not modified or is kept compatible.
-
-\layout Subsubsection*
-
-pdata access by SFR
-\begin_inset LatexCommand \index{sfr}
-
-\end_inset
-
-
-\layout Standard
-
-With the upcome of devices with internal xdata and flash memory devices
- using port P2 as dedicated I/O port is becoming more popular.
- Switching the high byte for pdata
-\begin_inset LatexCommand \index{pdata}
-
-\end_inset
-
- access which was formerly done by port P2 is then achieved by a Special
- Function Register.
- In well-established MCS51 tradition the address of this
-\emph on
-sfr
-\emph default
- is where the chip designers decided to put it.
- As pdata addressing is used in the startup code for the initialization
- of xdata variables a separate startup code should be used as described
- in section
-\begin_inset LatexCommand \ref{sub:Startup-Code}
-
-\end_inset
-
-.
-\layout Subsubsection*
-
-Other Features available by SFR
-\layout Standard
-
-Some MCS51 variants offer features like Double DPTR
-\begin_inset LatexCommand \index{DPTR}
-
-\end_inset
-
-, multiple DPTR, decrementing DPTR, 16x16 Multiply.
- These are currently not used for the MCS51 port.
- If you absolutely need them you can fall back to inline assembly or submit
- a patch to SDCC.
-\layout Subsection
-
-The Z80 and gbz80 port
-\layout Standard
-
-SDCC can target both the Zilog
-\begin_inset LatexCommand \index{Z80}
-
-\end_inset
-
- and the Nintendo Gameboy's Z80-like gbz80
-\begin_inset LatexCommand \index{gbz80 (GameBoy Z80)}
-
-\end_inset
-
-.
- The Z80 port is passed through the same
-\emph on
-regressions tests
-\begin_inset LatexCommand \index{Regression test}
-
-\end_inset
-
-
-\emph default
- as MCS51 and DS390 ports, so floating point support, support for long variables
- and bitfield support is fine.
- See mailing lists and forums about interrupt routines and access to I/O
- memory.
-\layout Standard
-
-As always, the code is the authoritative reference - see z80/ralloc.c and
- z80/gen.c.
- The stack
-\begin_inset LatexCommand \index{stack}
-
-\end_inset
-
- frame is similar to that generated by the IAR Z80 compiler.
- IX is used as the base pointer, HL is used as a temporary register, and
- BC and DE are available for holding variables.
- IY is currently unused.
- Return values
-\begin_inset LatexCommand \index{return value}
-
-\end_inset
-
- are stored in HL.
- One bad side effect of using IX as the base pointer is that a functions
- stack frame is limited to 127 bytes - this will be fixed in a later version.
-\layout Subsection
-
-The HC08 port
-\layout Standard
-
-The port to the Motorola HC08
-\begin_inset LatexCommand \index{HC08}
-
-\end_inset
-
- family has been added in October 2003, thank you Erik!
-\layout Section
-
-Retargetting for other MCUs.
+Retargetting for other Processors
\layout Standard
The issues for retargetting the compiler are far too numerous to be covered
\shape italic
This is an excerpt from an article published in Circuit Cellar Magazine
- in august 2000.
+ in
+\series bold
+August 2000
+\series default
+.
It's a little outdated (the compiler is much more efficient now and user/develo
per friendly), but pretty well exposes the guts of it all.
\shape default
There are other MCU specific considerations in this phase.
Some MCUs have an accumulator; very short-lived operands could be assigned
- to the accumulator instead of general-purpose register.
+ to the accumulator instead of a general-purpose register.
\layout Paragraph*
Code generation
\series bold
\shape italic
\color red
-<Where is Figure II ?>
+<Where is Figure II?>
+\layout Comment
+
+In the original article Figure II was announced to be downloadable on
+\shape italic
+Circuit Cellar
+\shape default
+'s web site.
+ Unfortunately it never seemed to have shown up there, so: where is Figure
+ II?
\layout Paragraph*
ICode Example
7.\SpecialChar ~
\SpecialChar ~
\SpecialChar ~
-short i=10; /* dead initialization eliminated */
+short i=10; \SpecialChar ~
+\SpecialChar ~
+/* dead initialization eliminated */
\newline
8.\SpecialChar ~
\SpecialChar ~
\SpecialChar ~
\SpecialChar ~
\SpecialChar ~
-mul += i * 3; /* this multiplication remains */
+mul += i * 3; \SpecialChar ~
+\SpecialChar ~
+/* this multiplication remains */
\newline
18.\SpecialChar ~
\SpecialChar ~
\SpecialChar ~
\SpecialChar ~
-gint += j * 3;/* this multiplication changed to addition */
+gint += j * 3;\SpecialChar ~
+\SpecialChar ~
+/* this multiplication changed to addition */
\newline
19.\SpecialChar ~
\SpecialChar ~
In addition the allocator also takes into consideration the type and usage
of a temporary, for example itemp6 is a pointer to near space and is used
as to fetch data from (i.e.
- used in GET_VALUE_AT_ADDRESS) so it is allocated a pointer registers (r0).
+ used in GET_VALUE_AT_ADDRESS) so it is allocated a pointer register (r0).
Some short lived temporaries are allocated to special registers which have
meaning to the code generator e.g.
iTemp13 is allocated to a pseudo register CC which tells the back end that
projects / fw / sdcc / blobdiff