\graphics default
\paperfontsize default
\spacing single
-\papersize Default
+\papersize letterpaper
\paperpackage a4
\use_geometry 1
\use_amsmath 0
Two resp.
three consecutive dashes simply result in a long resp.
extra long dash.
+\layout Comment
+
+Architecture specific stuff (like memory models, code examples) should maybe
+ go
+\layout Comment
+
+into seperate sections/chapters/appendices (it is hard to document PIC or
+ Z80 in
+\layout Comment
+
+a 8051 centered document)
\layout Title
SDCC Compiler User Guide
-\layout Standard
-\align center
-2003-06-02
\layout Comment
The strings enclosed in $ are automatically updated by cvs:
\layout Standard
\align center
-\size scriptsize
-cvs: $Revision$ $Date$
+\size footnotesize
+$Date$
+\layout Standard
+\align center
+
+\size footnotesize
+$Revision$
\layout Standard
\end_inset
, etc), Zilog Z80 based MCUs, and the Dallas DS80C390 variant.
- It can be retargetted for other microprocessors, support for PIC, AVR and
- 186 is under development.
+ 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 has extensive language extensions suitable for utilizing various microcont
\newline
The latest version can be downloaded from
-\begin_inset LatexCommand \url{http://sdcc.sourceforge.net/}
+\begin_inset LatexCommand \url{http://sdcc.sourceforge.net/snap.php}
\end_inset
\end_inset
-.
+ (see section
+\begin_inset LatexCommand \ref{sub:ANSI-Compliance}
+
+\end_inset
+
+ for ANSI-Compliance).
\newline
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.
-\layout Comment
-
-ANSI C reference / related tools / recommended reading / compiler building:
- Muchnik?
\layout Subsection
Wishes for the future
support for mcs51
\newline
+\newline
+
\family default
-If you can think of some more, please see the chapter 9 about filing feature
- requests
+If you can think of some more, please see the chapter
+\begin_inset LatexCommand \ref{sub:Requesting-Features}
+
+\end_inset
+
+ about filing feature requests
\begin_inset LatexCommand \index{Requesting features}
\end_inset
\layout Section
\pagebreak_top
-Installation
+Installing SDCC
\begin_inset LatexCommand \index{Installation}
\end_inset
+\layout Standard
+
+For most users it is sufficient to skip to either section
+\begin_inset LatexCommand \ref{sub:Building-SDCC-on-Linux}
+
+\end_inset
+
+ or section
+\begin_inset LatexCommand \ref{sub:Windows-Install}
+
+\end_inset
+
+.
+ More detailled instructions follow below.
\layout Subsection
Configure Options
\layout Standard
..
-\backslash
-
\end_inset
</cell>
</row>
\begin_inset Quotes srd
\end_inset
-compile on Cygwin for Mingw32(see also sdcc/support/scripts/sdcc_cygwin_mingw32)
-:
+compile on Cygwin for Mingw32 (see also sdcc/support/scripts/sdcc_cygwin_mingw32
+):
\layout LyX-Code
./configure -C
\layout Subsection
Install paths
+\begin_inset LatexCommand \label{sub:Install-paths}
+
+\end_inset
+
+
\begin_inset LatexCommand \index{Install paths}
\end_inset
\begin_inset Tabular
<lyxtabular version="3" rows="5" columns="4">
<features>
-<column alignment="center" valignment="top" leftline="true" width="0(null)">
-<column alignment="center" valignment="top" leftline="true" width="0(null)">
-<column alignment="center" valignment="top" leftline="true" width="0(null)">
-<column alignment="center" valignment="top" leftline="true" rightline="true" width="0(null)">
+<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 Subsection
Search Paths
+\begin_inset LatexCommand \label{sub:Search-Paths}
+
+\end_inset
+
+
\begin_inset LatexCommand \index{Search path}
\end_inset
\layout Subsubsection
Building SDCC on Linux
+\begin_inset LatexCommand \label{sub:Building-SDCC-on-Linux}
+
+\end_inset
+
+
\layout Enumerate
Unpack the file using a command like:
\family sans
\series bold
-"tar -xzf sdcc.src.tar.gz
+"tar -xvzf sdcc.src.tar.gz
\family default
\series default
"
They use Unix-sockets, which are not available on Win32.
\layout Subsubsection
-Windows Install Using a Binary Package
-\layout Enumerate
-
-Download the binary package and unpack it using your favorite unpacking
- tool (gunzip, WinZip, etc).
- This should unpack to a group of sub-directories.
- An example directory structure after unpacking the mingw32 package is:
- c:
-\backslash
-sdcc
-\backslash
-bin for the executables, c:
-\backslash
-sdcc
-\backslash
-include and c:
-\backslash
-sdcc
-\backslash
-lib for the include and libraries.
-\layout Enumerate
-
-Adjust your environment variable PATH to include the location of the bin
- directory or start sdcc using the full path.
-\layout Subsubsection
-
Building SDCC using Cygwin and Mingw32
\layout Standard
Win32-binary can be built, which will not need the Cygwin-DLL.
For the necessary 'configure' options see section 'configure options' or
- the script 'sdcc/support/scripts/sdcc_cygwinmingw32'.
+ the script 'sdcc/support/scripts/sdcc_cygwin_mingw32'.
\newline
\newline
\layout Standard
SDCC sources use the unix line ending LF.
- Life is much easier, if you store the source tree on a drive, which is
- mount in binary mode.
+ Life is much easier, if you store the source tree on a drive which is mounted
+ 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.
\layout Subsubsection
Building SDCC Using Microsoft Visual C++ 6.0/NET (MSVC)
\backslash
bin_vc to sdcc
\backslash
-bin, and you can compile using sdcc.
+bin, and you can compile using SDCC.
\layout Subsubsection
Building SDCC Using Borland
If you modify any source files and need to rebuild, be aware that the dependenci
es may not be correctly calculated.
The safest option is to delete all .obj files and run the build again.
- From a Cygwin BASH prompt, this can easily be done with the command:
+ From a Cygwin BASH prompt, this can easily be done with the command (be
+ sure you are in the sdcc directory):
\newline
\newline
\family default
\series default
from the sdcc directory.
+\layout Subsubsection
+
+Windows Install Using a Binary Package
+\begin_inset LatexCommand \label{sub:Windows-Install}
+
+\end_inset
+
+
+\layout Enumerate
+
+Download the binary package from
+\begin_inset LatexCommand \url{http://sdcc.sourceforge.net/snap.php}
+
+\end_inset
+
+ and unpack it using your favorite unpacking tool (gunzip, WinZip, etc).
+ This should unpack to a group of sub-directories.
+ An example directory structure after unpacking the mingw32 package is:
+ c:
+\backslash
+sdcc
+\backslash
+bin for the executables, c:
+\backslash
+sdcc
+\backslash
+include and c:
+\backslash
+sdcc
+\backslash
+lib for the include and libraries.
+\layout Enumerate
+
+Adjust your environment variable PATH to include the location of the bin
+ directory or start sdcc using the full path.
\layout Subsection
Building the Documentation
\layout Standard
-...
- coming soon
+If the necessary tools are installed it is as easy as changing into the
+ doc directory and typing
+\family sans
+\series bold
+
+\begin_inset Quotes srd
+\end_inset
+
+make
+\begin_inset Quotes srd
+\end_inset
+
+
+\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.knopper.net}
+
+\end_inset
+
+.
+ Prebuilt documentation in html and pdf format is available from
+\begin_inset LatexCommand \url{http://sdcc.sourceforge.net/snap.php}
+
+\end_inset
+
+.
+\layout Subsection
+
+Reading the Documentation
+\layout Standard
+
+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.
+\newline
+This documentation is in some aspects different from a commercial documentation:
+
+\layout Itemize
+
+It tries to document SDCC for several processor architectures in one document
+ (commercially these probably would be separate documents/products).
+ This document currently matches SDCC for mcs51 and DS390 best and does
+ give too few information about f.e.
+ Z80 and PIC.
+\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}
+
+\end_inset
+
+ together with a statement
+\begin_inset Quotes sld
+\end_inset
+
+some processors which are targetted by SDCC can be implemented in a field
+ programmable array
+\begin_inset LatexCommand \index{fpga (field programmable array)}
+
+\end_inset
+
+
+\begin_inset Quotes srd
+\end_inset
+
+ we expect you to have a quick look there and come back.
+ If you read this you are on the right track.
+\layout Itemize
+
+Some sections attribute more space to problems, restrictions and warnings
+ than to the solution.
+\layout Itemize
+
+The installation section and the section about the debugger is intimidating.
+\layout Itemize
+
+There are still lots of typos and there are more different writing styles
+ than pictures.
\layout Subsection
-Testing out the SDCC Compiler
+Testing the SDCC Compiler
\layout Standard
The first thing you should do after installing your SDCC compiler is to
If it doesn't run, or gives a message about not finding sdcc program, then
you need to check over your installation.
Make sure that the sdcc bin directory is in your executable search path
- defined by the PATH environment setting (see the Trouble-shooting section
- for suggestions).
+ defined by the PATH environment setting (
+\series medium
+see
+\series default
+section
+\begin_inset LatexCommand \ref{sub:Install-Trouble-shooting}
+
+\end_inset
+
+\SpecialChar ~
+
+\series medium
+Install trouble-shooting for suggestions
+\series default
+).
Make sure that the sdcc program is in the bin folder, if not perhaps something
did not install correctly.
\newline
\series medium
(no test.ihx, and the linker generates warnings), then the problem is most
- likely that sdcc cannot find the
+ likely that
+\series default
+SDCC
+\series medium
+ cannot find the
\series default
/
\series medium
\series default
\series medium
-(see the Install trouble-shooting section for suggestions).
+(see
+\series default
+section
+\begin_inset LatexCommand \ref{sub:Install-Trouble-shooting}
+
+\end_inset
+
+\SpecialChar ~
+
+\series medium
+Install trouble-shooting for suggestions).
\series default
\newline
\newline
\series medium
-The final test is to ensure sdcc can use the
+The final test is to ensure
+\series default
+SDCC
+\series medium
+ can use the
\series default
standard
\series medium
.
This should generate a test.ihx output file, and it should give no warnings
such as not finding the string.h file.
- If it cannot find the string.h file, then the problem is that sdcc cannot
- find the /usr/local/share/sdcc/include directory
+ If it cannot find the string.h file, then the problem is that
+\series default
+SDCC
+\series medium
+ cannot find the /usr/local/share/sdcc/include directory
\series default
\series medium
-(see the Install trouble-shooting section for suggestions).
+(see the
+\series default
+section
+\begin_inset LatexCommand \ref{sub:Install-Trouble-shooting}
+
+\end_inset
+
+\SpecialChar ~
+
+\series medium
+Install trouble-shooting section for suggestions).
\series default
Use option
\layout Subsection
Install Trouble-shooting
+\begin_inset LatexCommand \label{sub:Install-Trouble-shooting}
+
+\end_inset
+
+
\begin_inset LatexCommand \index{Install trouble-shooting}
\end_inset
\layout Standard
This will install the compiler, other executables libraries and include
- files in to the appropriate directories.
- See section
-\begin_inset Quotes sld
+ files into the appropriate directories.
+ See sections
+\begin_inset LatexCommand \ref{sub:Install-paths}
+
\end_inset
-Install and Search PATHS
-\begin_inset Quotes srd
+,\SpecialChar ~
+
+\begin_inset LatexCommand \ref{sub:Search-Paths}
+
\end_inset
-.
+\SpecialChar ~
+about install and search paths.
\newline
On most systems you will need super-user privileges to do this.
\layout Subsection
This is retargettable assembler & linkage editor, it was developed by Alan
Baldwin.
John Hartman created the version for 8051, and I (Sandeep) have made some
- enhancements and bug fixes for it to work properly with the SDCC.
+ enhancements and bug fixes for it to work properly with SDCC.
\layout Subsubsection
s51 - The Simulator
\end_inset
.
- It currently support the core mcs51, the Dallas DS80C390 and the Phillips
+ It currently supports the core mcs51, the Dallas DS80C390 and the Phillips
XA51 family.
\layout Subsubsection
\layout Standard
Sdcdb is the companion source level debugger.
- The current version of the debugger uses Daniel's Simulator S51, but can
- be easily changed to use other simulators.
+ 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.
\layout Section
\pagebreak_top
Using SDCC
\end_inset
.
- If you need another format you might want to use objdump
+ If you need another format you might want to use
+\family sans
+\shape italic
+objdump
+\family default
+\shape default
+
\begin_inset LatexCommand \index{objdump}
\end_inset
- or srecord
+ or
+\family sans
+\shape italic
+ srecord
+\family default
+\shape default
+
\begin_inset LatexCommand \index{srecord}
\end_inset
\end_inset
- An optional AOMF51 file containing debug information (with -
+ An optional AOMF51
+\begin_inset LatexCommand \index{AOMF51}
+
+\end_inset
+
+ file containing debug information (with -
\begin_inset ERT
status Collapsed
/
\end_inset
--debug)
+-debug).
+ This format is commonly used by third party tools (debuggers
+\begin_inset LatexCommand \index{Debugger}
+
+\end_inset
+
+, simulators, emulators)
\layout Itemize
sourcefile.dump*
\end_inset
-dumpall) (see section
+\begin_inset LatexCommand \ref{sub:Intermediate-Dump-Options}
+
+\end_inset
+
+\SpecialChar ~
+ and section
+\begin_inset LatexCommand \ref{sub:The-anatomy-of}
+
+\end_inset
+
+\SpecialChar ~
+
\begin_inset Quotes sld
\end_inset
\noun default
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
+ The linker is invoked from SDCC using a script file with extension .lnk
\begin_inset LatexCommand \index{.lnk}
\end_inset
\series default
- Generate code for the MCS51
+ Generate code for the Intel MCS51
\begin_inset LatexCommand \index{MCS51}
\end_inset
\series default
- Generate code for the DS80C390
+ Generate code for the Dallas DS80C390
\begin_inset LatexCommand \index{DS80C390}
\end_inset
\series default
- Generate code for the DS80C400
+ Generate code for the Dallas DS80C400
\begin_inset LatexCommand \index{DS80C400}
\end_inset
\series default
- Generate code for the Z80
+ Generate code for the Zilog Z80
\begin_inset LatexCommand \index{Z80}
\end_inset
processor (In development, not complete).
AVR users should probably have a look at avr-gcc
-\begin_inset LatexCommand \url[FIXME: official URL?]{ http://savannah.nongnu.org/download/avr-libc/snapshots/}
+\begin_inset LatexCommand \url{ http://savannah.nongnu.org/download/avr-libc/snapshots/}
\end_inset
\series default
- Generate code for the PIC 14
+ Generate code for the Microchip PIC 14
\begin_inset LatexCommand \index{PIC14}
\end_inset
--bit processors (In development, not complete).
+-bit processors (p16f84 and variants).
\layout Comment
p16f627 p16f628 p16f84 p16f873 p16f877?
\labelwidthstring 00.00.0000
+\series bold
+-mpic16
+\begin_inset LatexCommand \index{-mpic16}
+
+\end_inset
+
+
+\series default
+ Generate code for the Microchip PIC 16
+\begin_inset LatexCommand \index{PIC16}
+
+\end_inset
+
+-bit processors (p18f452 and variants).
+\layout List
+\labelwidthstring 00.00.0000
+
+
\series bold
-mtlcs900h
\series default
\series default
Command line definition of macros.
- Passed to the pre processor.
+ Passed to the preprocessor.
\layout List
\labelwidthstring 00.00.0000
'-newline if it is long.
The list of rules is printed on standard output instead of the preprocessed
C program.
- `-M' implies `-E'.
+ `-M' implies `-E
+\begin_inset LatexCommand \index{-E}
+
+\end_inset
+
+'.
\layout List
\labelwidthstring 00.00.0000
\series bold
--Aquestion
-\series default
- (answer) Assert the answer answer for question, in case it is tested with
- a preprocessor conditional such as `#if #question(answer)'.
- `-A-' disables the standard assertions that normally describe the target
- machine.
-\layout List
-\labelwidthstring 00.00.0000
-
-
-\series bold
--Umacro
-\begin_inset LatexCommand \index{-Umacro}
-
-\end_inset
-
-
+-Umacro
+\begin_inset LatexCommand \index{-Umacro}
+
+\end_inset
+
+
\series default
Undefine macro macro.
`-U' options are evaluated after all `-D' options, but before any `-include'
\labelwidthstring 00.00.0000
+\series bold
+-
+\begin_inset ERT
+status Collapsed
+
+\layout Standard
+
+\backslash
+/
+\end_inset
+
+-model-small
+\begin_inset LatexCommand \index{-\/-model-small}
+
+\end_inset
+
+
+\series default
+\size large
+\emph on
+
+\size default
+\emph default
+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
\series default
Generate code for Large model programs see section Memory Models for more
details.
- If this option is used all source files in the project should be compiled
+ If this option is used all source files in the project have to be compiled
with this option.
- In addition the standard library routines are compiled with small model,
- they will need to be recompiled.
\layout List
\labelwidthstring 00.00.0000
/
\end_inset
--model-small
-\begin_inset LatexCommand \index{-\/-model-small}
+-xstack
+\begin_inset LatexCommand \index{-\/-xstack}
\end_inset
\series default
-\size large
-\emph on
-
-\size default
-\emph default
-Generate code for Small Model programs see section Memory Models for more
- details.
- This is the default model.
+ Uses a pseudo stack in the first 256 bytes in the external ram for allocating
+ variables and passing parameters.
+ See section
+\begin_inset LatexCommand \ref{sub:External-Stack}
+
+\end_inset
+
+\SpecialChar ~
+ External Stack for more details.
+\layout List
+\labelwidthstring 00.00.0000
+
+
+\series bold
+-
+\begin_inset ERT
+status Collapsed
+
+\layout Standard
+
+\backslash
+/
+\end_inset
+
+-iram-size
+\series default
+<Value>
+\begin_inset LatexCommand \index{-\/-iram-size<Value>}
+
+\end_inset
+
+ Causes the linker to check if the internal ram 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
+
+-xram-size
+\series default
+<Value>
+\begin_inset LatexCommand \index{-\/-xram-size<Value>}
+
+\end_inset
+
+ Causes the linker to check if the external ram 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
+
+-code-size
+\series default
+<Value>
+\begin_inset LatexCommand \index{-\/-data-loc}
+
+\end_inset
+
+ Causes the linker to check if the code memory usage is within limits of
+ the given value.
\layout Subsubsection
DS390 Options
).
\layout Subsubsection
+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
+Force a called function to always save BC.
+\layout List
+\labelwidthstring 00.00.0000
+
+
+\series bold
+-
+\begin_inset ERT
+status Collapsed
+
+\layout Standard
+
+\backslash
+/
+\end_inset
+
+-no-std-crt0
+\series default
+
+\begin_inset LatexCommand \index{-\/-no-std-crt0}
+
+\end_inset
+
+ When linking, skip the standard crt0.o object file.
+ You must provide your own crt0.o for your system when linking.
+
+\layout Subsubsection
+
Optimization Options
\begin_inset LatexCommand \index{Options optimization}
\end_inset
are implemented using jump-tables.
- See section Switch Statements for more details.
+ See section
+\begin_inset LatexCommand \ref{sub:'switch'-Statements}
+
+\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}
\series default
- Will not memcpy initialized data in far space from code space.
+ 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.
\layout Subsubsection
/
\end_inset
--xstack
-\begin_inset LatexCommand \index{-\/-xstack}
+-callee-saves
+\begin_inset LatexCommand \index{-\/-callee-saves}
\end_inset
+ function1[,function2][,function3]....
\series default
- Uses a pseudo stack in the first 256 bytes in the external ram for allocating
- variables and passing parameters.
- See section on external stack for more details.
-\layout List
-\labelwidthstring 00.00.0000
-
-
+ 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 the register saving convention for the
+ function names specified.
+ The compiler will not save registers when calling these functions, no extra
+ code will be generated at the entry & exit (function prologue
\series bold
--
-\begin_inset ERT
-status Collapsed
-\layout Standard
+\begin_inset LatexCommand \index{function prologue}
-\backslash
-/
\end_inset
--callee-saves
-\begin_inset LatexCommand \index{-\/-callee-saves}
-
-\end_inset
+\series default
+ & epilogue
+\series bold
-\begin_inset LatexCommand \index{function prologue}
+\begin_inset LatexCommand \index{function epilogue}
\end_inset
- function1[,function2][,function3]....
\series default
- 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 the register saving convention for the
- function names specified.
- The compiler will not save registers when calling these functions, no extra
- code will be generated 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.
+) 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) will be able
to determine the appropriate scheme to use for each function call.
DO NOT use this option for built-in functions such as _mulint..., if this
\series bold
--
-\begin_inset ERT
-status Collapsed
-
-\layout Standard
-
-\backslash
-/
-\end_inset
-
--peep-file
-\series default
-
-\begin_inset LatexCommand \index{-\/-peep-file}
-
-\end_inset
-
-<filename> This option can be used to use additional rules to be used by
- the peep hole optimizer.
- See section Peep Hole optimizations for details on how to write these rules.
-\layout List
-\labelwidthstring 00.00.0000
-
-
-\series bold
--S
-\begin_inset LatexCommand \index{-S}
+-S
+\begin_inset LatexCommand \index{-S}
\end_inset
\end_inset
-.See section Installation for more details.
+.
+ See section Installation for more details.
\layout List
\labelwidthstring 00.00.0000
\end_inset
function.
- The default option is to lock up i.e.
- generate a 'ljmp '.
+ The default setting is to lock up i.e.
+ generate a '
+\family typewriter
+ljmp .
+\family default
+'.
\layout List
\labelwidthstring 00.00.0000
/
\end_inset
--no-peep
-\begin_inset LatexCommand \index{-\/-no-peep}
-
-\end_inset
-
-
+-peep-file
\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-asm
-\begin_inset LatexCommand \index{-\/-peep-asm}
+\begin_inset LatexCommand \index{-\/-peep-file}
\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}
+<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
- rules defined in the source file tree '<target>/peeph.def' before using
- this option.
+\SpecialChar ~
+Peep Hole optimizations for details on how to write these rules.
\layout List
\labelwidthstring 00.00.0000
/
\end_inset
--iram-size
-\series default
-<Value>
-\begin_inset LatexCommand \index{-\/-iram-size<Value>}
+-no-peep
+\begin_inset LatexCommand \index{-\/-no-peep}
\end_inset
- Causes the linker to check if the internal ram usage is within limits of
- the given value.
+
+\series default
+ Disable peep-hole optimization.
\layout List
\labelwidthstring 00.00.0000
/
\end_inset
--xram-size
-\series default
-<Value>
-\begin_inset LatexCommand \index{-\/-xram-size<Value>}
+-peep-asm
+\begin_inset LatexCommand \index{-\/-peep-asm}
\end_inset
- Causes the linker to check if the external ram 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
--code-size
\series default
-<Value>
-\begin_inset LatexCommand \index{-\/-code-size<Value>}
+ 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
- Causes the linker to check if the code usage is within limits of the given
- value.
+ rules defined in the source file tree '<target>/peeph.def' before using
+ this option.
\layout List
\labelwidthstring 00.00.0000
\series default
- Disable some of the more pedantic warnings (jwk burps: please be more specific
- here, please!)
+ 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
+
+.
\layout List
\labelwidthstring 00.00.0000
\series default
- Display the errors and warnings using MSVC style, so you can use SDCC with
- visual studio
+ Display errors and warnings using MSVC style, so you can use SDCC with
+ visual studio.
+\layout List
+\labelwidthstring 00.00.0000
+
+
+\series bold
+-
+\begin_inset ERT
+status Collapsed
+
+\layout Standard
+
+\backslash
+/
+\end_inset
+
+-use-stdout
+\begin_inset LatexCommand \index{-\/-use-stdout}
+
+\end_inset
+
+
+\series default
+ Send errors and warnings to stdout instead of stderr.
\layout Subsubsection
Intermediate Dump Options
+\begin_inset LatexCommand \label{sub:Intermediate-Dump-Options}
+
+\end_inset
+
+
\begin_inset LatexCommand \index{Options intermediate dump}
\end_inset
\size default
\bar default
Will cause all the above mentioned dumps to be created.
+\layout Subsubsection
+
+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
+
+.
+ 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 -
+\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 Subsection
Environment variables
\series bold
-TMP
-\begin_inset LatexCommand \index{TMP}
-
-\end_inset
-
-,\SpecialChar ~
-TEMP
-\begin_inset LatexCommand \index{TEMP}
-
-\end_inset
-
-,\SpecialChar ~
+TMP,\SpecialChar ~
+TEMP,\SpecialChar ~
TMPDIR
-\begin_inset LatexCommand \index{TMPDIR}
+\begin_inset LatexCommand \index{TMP, TEMP, TMPDIR}
\end_inset
\series default
- Path, see
+ Path, see section
+\begin_inset LatexCommand \ref{sub:Install-paths}
+
+\end_inset
+
+\SpecialChar ~
+
\begin_inset Quotes sld
\end_inset
-2.3 Install and search paths
+ Install Paths
\begin_inset Quotes srd
\end_inset
\series default
- Path, see
+ Path, see section
+\begin_inset LatexCommand \ref{sub:Search-Paths}
+
+\end_inset
+
+\SpecialChar ~
+
\begin_inset Quotes sld
\end_inset
-2.3 Install and search paths
+Search Paths
\begin_inset Quotes srd
\end_inset
\series default
- Path, see
+ Path, see section
+\begin_inset LatexCommand \ref{sub:Search-Paths}
+
+\end_inset
+
+\SpecialChar ~
+
\begin_inset Quotes sld
\end_inset
-2.3 Install and search paths
+Search Paths
\begin_inset Quotes srd
\end_inset
-.
+..
\layout Standard
There are some more environment variables recognized by SDCC, but these
specific storage classes.
\layout Subsubsection
-xdata
-\begin_inset LatexCommand \index{xdata}
+data
+\begin_inset LatexCommand \index{data}
\end_inset
\layout Standard
-Variables declared with this storage class will be placed in the extern
- RAM.
- This is the
+This is the
\series bold
default
\series default
- storage class for Large Memory model, e.g.:
+ storage class for the Small Memory model.
+ 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
+
+
+\family typewriter
+data unsigned char test_data;
+\layout Standard
+
+Writing 0x01 to this variable generates the assembly code:
\layout Verse
\family typewriter
-xdata unsigned char xduc;
+75*00 01\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+mov\SpecialChar ~
+\SpecialChar ~
+_test_data,#0x01
\layout Subsubsection
-data
-\begin_inset LatexCommand \index{data}
+xdata
+\begin_inset LatexCommand \index{xdata}
\end_inset
\layout Standard
-This is the
+Variables declared with this storage class will be placed in the external
+ RAM.
+ This is the
\series bold
default
\series default
- storage class for Small Memory model.
- Variables declared with this storage class will be allocated in the internal
- RAM, e.g.:
+ storage class for the Large Memory model, e.g.:
+\layout Verse
+
+
+\family typewriter
+xdata unsigned char test_xdata;
+\layout Standard
+
+Writing 0x01 to this variable generates the assembly code:
\layout Verse
\family typewriter
-data int iramdata;
+90s00r00\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+mov\SpecialChar ~
+\SpecialChar ~
+dptr,#_test_xdata
+\newline
+74\SpecialChar ~
+01\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+mov\SpecialChar ~
+\SpecialChar ~
+a,#0x01
+\newline
+F0\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+movx\SpecialChar ~
+@dptr,a
\layout Subsubsection
idata
\family typewriter
-idata int idi;
+idata unsigned char test_idata;
+\layout Standard
+
+Writing 0x01 to this variable generates the assembly code:
+\layout Verse
+
+
+\family typewriter
+78r00\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+mov\SpecialChar ~
+\SpecialChar ~
+r0,#_test_idata
+\newline
+76\SpecialChar ~
+01\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+mov\SpecialChar ~
+\SpecialChar ~
+@r0,#0x01
+\layout Subsubsection
+
+pdata
+\begin_inset LatexCommand \index{pdata}
+
+\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.
+ 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).
+\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
+}
+\layout Standard
+
+Generates the assembly code:
+\layout Verse
+
+
+\family typewriter
+75*01 FE\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+mov\SpecialChar ~
+ _test_pdata_ptr,#0xFE
+\newline
+78 FE\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+mov\SpecialChar ~
+ r0,#0xFE
+\newline
+74 01\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+mov\SpecialChar ~
+ a,#0x01
+\newline
+F2\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+movx @r0,a
+\layout Standard
+
+Be extremely carefull if you use pdata together with the -
+\begin_inset ERT
+status Collapsed
+
+\layout Standard
+
+\backslash
+/
+\end_inset
+
+-xstack
+\begin_inset LatexCommand \index{-\/-xstack}
+
+\end_inset
+
+ option.
+\layout Subsubsection
+
+code
+\begin_inset LatexCommand \index{code}
+
+\end_inset
+
+
+\layout Standard
+
+'Variables' declared with this storage class will be placed in the code
+ memory:
+\layout Verse
+
+
+\family typewriter
+code unsigned char test_code;
+\layout Standard
+
+Read access to this variable generates the assembly code:
+\layout Verse
+
+
+\family typewriter
+90s00r6F\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+mov dptr,#_test_code
+\newline
+E4\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+clr a
+\newline
+93\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+movc a,@a+dptr
\layout Subsubsection
bit
\family typewriter
-bit iFlag;
+bit test_bit;
+\layout Standard
+
+Writing 1 to this variable generates the assembly code:
+\layout Verse
+
+
+\family typewriter
+D2*00\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+setb\SpecialChar ~
+_test_bit
\layout Subsubsection
sfr
\family typewriter
-sfr at 0x80 P0; /* special function register P0 at location 0x80 */
+sfr at
+\begin_inset LatexCommand \index{at}
+
+\end_inset
+
+ 0x80 P0;\SpecialChar ~
+ /* special function register P0 at location 0x80 */
\newline
sbit at 0xd7 CY; /* CY (Carry Flag
\begin_inset LatexCommand \index{Flags}
\end_inset
) */
-\layout Subsection
+\layout Subsubsection
Pointers
\begin_inset LatexCommand \index{Pointers}
\end_inset
-
+ to MCS51/DS390 specific memory spaces
\layout Standard
SDCC allows (via language extensions) pointers to explicitly point to any
\family typewriter
-/* pointer physically in xternal ram pointing to object in internal ram
+/* pointer physically in internal ram pointing to object in external ram
+ */
+\newline
+xdata unsigned char * data p;
+\newline
+
+\newline
+/* pointer physically in external ram pointing to object in internal ram
*/
\newline
data unsigned char * xdata p;
code.
\layout Subsection
-Parameters
-\begin_inset LatexCommand \index{Parameters}
-
-\end_inset
-
- & Local Variables
-\begin_inset LatexCommand \index{Local variable}
+Absolute Addressing
+\begin_inset LatexCommand \index{Absolute addressing}
\end_inset
\layout Standard
-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
+Data items can be assigned an absolute address with the
\emph on
-static
-\begin_inset LatexCommand \index{static}
+at
+\begin_inset LatexCommand \index{at}
\end_inset
-
+ <address>
\emph default
- so by default functions are non-reentrant
-\begin_inset LatexCommand \index{reentrant}
-
-\end_inset
+ keyword, in addition to a storage class, e.g.:
+\layout Verse
-.
-\newline
-\newline
-They can be placed on the stack
-\begin_inset LatexCommand \index{stack}
+\family typewriter
+xdata
+\begin_inset LatexCommand \index{xdata}
\end_inset
- either by using the
-\emph on
- -
-\begin_inset ERT
-status Collapsed
-
-\layout Standard
-
-\backslash
-/
-\end_inset
-
--stack-auto
-\begin_inset LatexCommand \index{-\/-stack-auto}
-
-\end_inset
-
-
-\emph default
- option or by using the
-\emph on
-reentrant
-\begin_inset LatexCommand \index{reentrant}
+ at
+\begin_inset LatexCommand \index{at}
\end_inset
-
-\emph default
- keyword in the function declaration, e.g.:
-\layout Verse
-
-
-\family typewriter
-unsigned char foo(char i) reentrant
-\newline
-{
-\newline
-...
-
-\newline
-}
+ 0x7ffe unsigned int chksum;
\layout Standard
-Since stack space on 8051 is limited, the
-\emph on
-reentrant
-\emph default
-keyword or the
-\emph on
- -
-\begin_inset ERT
-status Collapsed
-
-\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{.lst}
-\backslash
-/
\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}
+) and the linker output files (.rst
+\begin_inset LatexCommand \index{.rst}
\end_inset
- addresses, e.g.:
-\layout Verse
-
-
-\family typewriter
-unsigned char foo() {
-\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
+) and (.map
+\begin_inset LatexCommand \index{.map}
-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
-\emph on
- j
-\emph default
- in internal ram.
- When compiled with
-\emph on
--
-\begin_inset ERT
-status Collapsed
+\end_inset
+) are good places to look for such overlaps.
\layout Standard
-\backslash
-/
-\end_inset
-
--stack-auto
-\emph default
- or when a function is declared as
+In case of memory mapped I/O devices the keyword
\emph on
-reentrant
+volatile
\emph default
- this should only be done for static variables.
-\layout Standard
-
-Parameters however are not allowed any storage class, (storage classes for
- parameters will be ignored), their allocation is governed by the memory
- model in use, and the reentrancy options.
-\layout Subsection
-
-Overlaying
-\begin_inset LatexCommand \index{Overlaying}
-
-\end_inset
-
+ should be used to tell the compiler that accesses might not be optimized
+ away:
+\layout Verse
-\layout Standard
-For non-reentrant
-\begin_inset LatexCommand \index{reentrant}
+\family typewriter
+volatile
+\begin_inset LatexCommand \index{volatile}
\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}
+ xdata
+\begin_inset LatexCommand \index{xdata}
\end_inset
- is small.
-
-\emph default
- If an explicit storage class
-\begin_inset LatexCommand \index{Storage class}
+ at
+\begin_inset LatexCommand \index{at}
\end_inset
- is specified for a local variable, it will NOT be overlayed.
+ 0x8000 unsigned char PORTA_8255;
\layout Standard
-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}
-
-\end_inset
+Absolute address can be specified for variables in all storage classes,
+ e.g.:
+\layout Verse
- if they are not reentrant.
-\layout Standard
-Also note that the compiler does not do any processing of inline
-\begin_inset LatexCommand \index{inline}
+\family typewriter
+bit
+\begin_inset LatexCommand \index{bit}
\end_inset
- 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}
+ at
+\begin_inset LatexCommand \index{at}
\end_inset
- or division
-\begin_inset LatexCommand \index{Division}
-
-\end_inset
+ 0x02 bvar;
+\layout Standard
- will NOT be overlayed since these are implemented using external functions,
- e.g.:
+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
-#pragma SAVE
+extern volatile bit SDI;
+\newline
+extern volatile bit SCLK;
+\newline
+extern volatile bit CPOL;
\newline
-#pragma NOOVERLAY
-\begin_inset LatexCommand \index{\#pragma NOOVERLAY}
-
-\end_inset
-
\newline
-void set_error(unsigned char errcd)
+void DS1306_put(unsigned char value)
\newline
{
\newline
\SpecialChar ~
\SpecialChar ~
\SpecialChar ~
-P3 = errcd;
-\newline
-}
-\newline
-#pragma RESTORE
+unsigned char mask=0x80;
\newline
\newline
-void some_isr () interrupt
-\begin_inset LatexCommand \index{interrupt}
-
-\end_inset
-
- 2 using
-\begin_inset LatexCommand \index{using}
-
-\end_inset
-
- 1
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+while(mask)
\newline
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
{
\newline
\SpecialChar ~
\SpecialChar ~
\SpecialChar ~
\SpecialChar ~
-...
-\newline
\SpecialChar ~
\SpecialChar ~
\SpecialChar ~
\SpecialChar ~
-set_error(10);
+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
}
\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 Subsection
+Then, someplace in the code for the first hardware you would use
+\layout Verse
-Interrupt Service Routines
+
+\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
-SDCC allows interrupt service routines to be coded in C, with some extended
- keywords.
+Similarly, for the second hardware you would use
\layout Verse
\family typewriter
-void timer_isr (void) interrupt 2 using 1
-\newline
-{
+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 CPOL;\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+/* This is a variable, let the linker allocate this one */
\layout Standard
-The number following the
-\emph on
-interrupt
-\begin_inset LatexCommand \index{interrupt}
+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 Subsection
-\end_inset
+Parameters
+\begin_inset LatexCommand \index{Parameters}
+\end_inset
-\emph default
- keyword is the interrupt number this routine will service.
- 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 is used to tell the compiler to use the specified register bank
- (8051 specific) when generating code for this function.
- 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}
+ & Local Variables
+\begin_inset LatexCommand \index{Local variable}
\end_inset
- if it is not reentrant.
- A special note here, int (16 bit) and long (32 bit) integer division
-\begin_inset LatexCommand \index{Division}
+
+\layout Standard
+
+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
+static
+\begin_inset LatexCommand \index{static}
\end_inset
-, multiplication
-\begin_inset LatexCommand \index{Multiplication}
+
+\emph default
+ so by default functions are non-reentrant
+\begin_inset LatexCommand \index{reentrant}
\end_inset
- & modulus
-\begin_inset LatexCommand \index{Modulus}
+.
+
+\newline
+
+\newline
+They can be placed on the stack
+\begin_inset LatexCommand \index{stack}
\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
+ either by using the
\emph on
-
\begin_inset ERT
\emph default
- option and the source file will need to be compiled using the
+ option or by using the
\emph on
--
-\begin_inset ERT
-status Collapsed
-
-\layout Standard
+reentrant
+\begin_inset LatexCommand \index{reentrant}
-\backslash
-/
\end_inset
--int-long-ren
+
\emph default
-t
-\begin_inset LatexCommand \index{-\/-int-long-rent}
+ keyword in the function declaration, e.g.:
+\layout Verse
-\end_inset
- compiler option.
+\family typewriter
+unsigned char foo(char i) reentrant
+\newline
+{
+\newline
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+...
+
+\newline
+}
\layout Standard
-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
+Since stack space on 8051 is limited, the
\emph on
-main
+reentrant
\emph default
-.
-\layout Standard
-
-Interrupt Numbers and the corresponding address & descriptions for the Standard
- 8051 are listed below.
- SDCC will automatically adjust the interrupt vector table to the maximum
- interrupt number specified.
-\newline
-
-\layout Standard
-\align center
-
-\begin_inset Tabular
-<lyxtabular version="3" rows="6" 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
+keyword or the
+\emph on
+ -
+\begin_inset ERT
+status Collapsed
\layout Standard
-Interrupt #
+\backslash
+/
\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
+-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
-\layout Standard
+\newline
+Local variables can be assigned storage classes and absolute
+\begin_inset LatexCommand \index{Absolute addressing}
-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
+ addresses, e.g.:
+\layout Verse
-\layout Standard
-
-External 0
-\end_inset
-</cell>
-<cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
-\begin_inset Text
+\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
-0x0003
-\end_inset
-</cell>
-</row>
-<row topline="true">
-<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
-\begin_inset Text
+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
+\emph on
+ j
+\emph default
+ in internal ram.
+ When compiled with
+\emph on
+-
+\begin_inset ERT
+status Collapsed
\layout Standard
-1
+\backslash
+/
\end_inset
-</cell>
-<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
-\begin_inset Text
+-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
-Timer 0
-\end_inset
-</cell>
-<cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
-\begin_inset Text
+Parameters however are not allowed any storage class, (storage classes for
+ parameters will be ignored), their allocation is governed by the memory
+ model in use, and the reentrancy options.
+\layout Subsection
-\layout Standard
+Overlaying
+\begin_inset LatexCommand \label{sub:Overlaying}
-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
-\end_inset
-</cell>
-<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
-\begin_inset Text
-\layout Standard
+\begin_inset LatexCommand \index{Overlaying}
-External 1
\end_inset
-</cell>
-<cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
-\begin_inset Text
-
-\layout Standard
-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
-\end_inset
-</cell>
-<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
-\begin_inset Text
-
-\layout Standard
+For non-reentrant
+\begin_inset LatexCommand \index{reentrant}
-Timer 1
\end_inset
-</cell>
-<cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
-\begin_inset Text
-\layout Standard
+ 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}
-0x001B
\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
+ is small.
+
+\emph default
+ If an explicit storage class
+\begin_inset LatexCommand \index{Storage class}
-4
\end_inset
-</cell>
-<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
-\begin_inset Text
+ is specified for a local variable, it will NOT be overlayed.
\layout Standard
-Serial
+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}
+
\end_inset
-</cell>
-<cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
-\begin_inset Text
+ if they are not reentrant.
\layout Standard
-0x0023
-\end_inset
-</cell>
-</row>
-</lyxtabular>
+Also note that the compiler does not do any processing of inline
+\begin_inset LatexCommand \index{inline}
\end_inset
-
-\newline
-
+ 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
-If the interrupt service routine is defined without
-\emph on
-using
-\begin_inset LatexCommand \index{using}
+Parameters and Local variables of functions that contain 16 or 32 bit multiplica
+tion
+\begin_inset LatexCommand \index{Multiplication}
\end_inset
+ or division
+\begin_inset LatexCommand \index{Division}
-\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
+ will NOT be overlayed since these are implemented using external functions,
+ e.g.:
+\layout Verse
-Calling other functions from an interrupt service routine is not recommended,
- avoid it if possible.
-\newline
+\family typewriter
+#pragma SAVE
\newline
-Also see the _naked modifier.
-\layout Subsection
-
-Critical Functions
-\layout Standard
-
+#pragma NOOVERLAY
+\begin_inset LatexCommand \index{\#pragma NOOVERLAY}
-\shape italic
-<TODO: this isn't implemented at all!>
-\shape default
+\end_inset
+
+\newline
+void set_error(unsigned char errcd)
+\newline
+{
+\newline
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+P3 = errcd;
+\newline
+}
+\newline
+#pragma RESTORE
\newline
\newline
-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 upon entry to a critical
- function and enable them back before returning.
- Note that nesting critical functions may cause unpredictable results.
-\layout Verse
+void some_isr () interrupt
+\begin_inset LatexCommand \index{interrupt}
+\end_inset
-\family typewriter
-int foo () critical
-\newline
-{
+ 2
\newline
-...
-
+{
\newline
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
...
-
\newline
-}
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+set_error(10);
+\newline
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+...
+
+\newline
+}
\layout Standard
-The critical attribute maybe used with other attributes like
+In the above example the parameter
\emph on
-reentrant.
+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 Subsection
-Naked Functions
-\begin_inset LatexCommand \index{Naked functions}
+Interrupt Service Routines
+\begin_inset LatexCommand \label{sub:Interrupt-Service-Routines}
\end_inset
\layout Standard
-A special keyword may be associated with a function declaring it as
+SDCC allows interrupt service routines to be coded in C, with some extended
+ keywords.
+\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
-_naked
-\begin_inset LatexCommand \index{\_naked}
+interrupt
+\begin_inset LatexCommand \index{interrupt}
\end_inset
-.
-
+
\emph default
-The
+ 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
-_naked
+using
\emph default
- function modifier attribute prevents the compiler from generating prologue
-\begin_inset LatexCommand \index{function prologue}
+ 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
+
+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
+.
+\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
+
+\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
+
+\layout Standard
+Interrupt #
\end_inset
+</cell>
+<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
+\begin_inset Text
- and epilogue
-\begin_inset LatexCommand \index{function epilogue}
+\layout Standard
+Description
\end_inset
+</cell>
+<cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
+\begin_inset Text
- 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
+\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
-\family typewriter
-data unsigned char counter;
-\newline
-void simpleInterrupt(void) interrupt
-\begin_inset LatexCommand \index{interrupt}
+\layout Standard
+0
\end_inset
+</cell>
+<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
+\begin_inset Text
- 1
-\newline
-{
-\newline
-\SpecialChar ~
-\SpecialChar ~
-\SpecialChar ~
-\SpecialChar ~
-counter++;
-\newline
-}
-\newline
+\layout Standard
-\newline
-void nakedInterrupt(void) interrupt 2 _naked
-\newline
-{
-\newline
-\SpecialChar ~
-\SpecialChar ~
-\SpecialChar ~
-\SpecialChar ~
-_asm
-\begin_inset LatexCommand \index{\_asm}
+External 0
+\end_inset
+</cell>
+<cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
+\begin_inset Text
+
+\layout Standard
+0x0003
\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 ~
-\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 in _naked function.
-\newline
-\SpecialChar ~
-\SpecialChar ~
-\SpecialChar ~
-\SpecialChar ~
-_endasm
-\begin_inset LatexCommand \index{\_endasm}
+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
-}
\layout Standard
-For an 8051 target, the generated simpleInterrupt looks like:
-\layout Verse
+0x000B
+\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
-_simpleIterrupt:
-\newline
-\SpecialChar ~
-\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
-\newline
-\SpecialChar ~
-\SpecialChar ~
-\SpecialChar ~
-\SpecialChar ~
-reti
-\layout Standard
+2
+\end_inset
+</cell>
+<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
+\begin_inset Text
-whereas nakedInterrupt looks like:
-\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
-_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(i) in _naked function.
\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
+0x0013
+\end_inset
+</cell>
+</row>
+<row topline="true">
+<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
+\begin_inset Text
-Functions using private banks
-\begin_inset LatexCommand \index{bank}
+\layout Standard
+3
\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
\layout Standard
-The
-\emph on
-using
-\begin_inset LatexCommand \index{using}
+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
\end_inset
+</cell>
+<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
+\begin_inset Text
+\layout Standard
-\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}
+Serial
+\end_inset
+</cell>
+<cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
+\begin_inset Text
+\layout Standard
+
+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
-\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
-\emph on
-non-interrupt
-\emph default
- function (but may occasionally be useful anyway
-\begin_inset Foot
-collapsed false
+Timer 2 (8052)
+\end_inset
+</cell>
+<cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
+\begin_inset Text
\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
+0x002B
\end_inset
+</cell>
+</row>
+</lyxtabular>
+
+\end_inset
+
-).
\newline
-\emph on
-(pending: I don't think this has been done yet)
\layout Standard
-An
+If the interrupt service routine is defined without
\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}
+using
+\begin_inset LatexCommand \index{using}
\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
+ 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
+
+If the interrupt service routine is defined to be using a specific register
+ bank then only
\emph on
-using
+a, b & dptr
\emph default
- the same bank, terrible and bad things can happen.
- To prevent this, no single register bank should be
+ 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
+
+Using interrupts opens the door for some very interesting bugs:
+\layout Standard
+
+If the interrupt service routines changes variables which are accessed by
+ other functions these variables should be declared
\emph on
-used
+volatile
\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
-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 Subsection
+\begin_inset LatexCommand \index{volatile}
-Absolute Addressing
-\begin_inset LatexCommand \index{Absolute addressing}
+\end_inset
+
+.
+ If the access to these variables is not
+\emph on
+atomic
+\begin_inset LatexCommand \index{atomic access}
\end_inset
-\layout Standard
+\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
-Data items can be assigned an absolute address with the
-\emph on
-at
-\begin_inset LatexCommand \index{at}
+\family typewriter
+flags\SpecialChar ~
+|=\SpecialChar ~
+0x80;
+\family default
+
+\begin_inset Quotes sld
\end_inset
- <address>
-\emph default
- keyword, in addition to a storage class, e.g.:
-\layout Verse
+ is not atomic if
+\family typewriter
+flags
+\family default
+ resides in xdata.
+ Setting
+\begin_inset Quotes srd
+\end_inset
\family typewriter
-xdata
-\begin_inset LatexCommand \index{xdata}
+flags\SpecialChar ~
+|=\SpecialChar ~
+0x40;
+\family default
+\begin_inset Quotes sld
\end_inset
- at
-\begin_inset LatexCommand \index{at}
+ 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
- 0x8000 unsigned char PORTA_8255 ;
+ 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
-In the above example the PORTA_8255 will be allocated to the location 0x8000
- of the external ram.
- Note that this feature is provided to give the programmer access to
-\emph on
-memory mapped
-\emph default
- devices attached to the controller.
- 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{.lst}
+A special note here, int (16 bit) and long (32 bit) integer division
+\begin_inset LatexCommand \index{Division}
\end_inset
-) and the linker output files (.rst
-\begin_inset LatexCommand \index{.rst}
+, multiplication
+\begin_inset LatexCommand \index{Multiplication}
\end_inset
-) and (.map
-\begin_inset LatexCommand \index{.map}
+ & modulus
+\begin_inset LatexCommand \index{Modulus}
\end_inset
-) are a good places to look for such overlaps.
-\newline
+ and floating-point
+\begin_inset LatexCommand \index{Floating point support}
-\newline
-Absolute address can be specified for variables in all storage classes,
- e.g.:
-\layout Verse
+\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
-\family typewriter
-bit
-\begin_inset LatexCommand \index{bit}
+\layout Standard
+\backslash
+/
\end_inset
- at
-\begin_inset LatexCommand \index{at}
+-stack-auto
+\begin_inset LatexCommand \index{-\/-stack-auto}
\end_inset
- 0x02 bvar;
+
+\emph default
+ option and the source file will need to be compiled using the
+\emph on
+-
+\begin_inset ERT
+status Collapsed
+
\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 you routine using
-\layout Verse
+\backslash
+/
+\end_inset
+-int-long-ren
+\emph default
+t
+\begin_inset LatexCommand \index{-\/-int-long-rent}
-\family typewriter
-extern bit SDI;
-\newline
-extern bit SCLK;
-\newline
-extern bit CPOL;
-\newline
+\end_inset
-\newline
-void DS1306_put(unsigned char value)
-\newline
-{
-\newline
-\SpecialChar ~
-\SpecialChar ~
-\SpecialChar ~
-\SpecialChar ~
-unsigned char mask=0x80;
+ compiler option.
+\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
+
+ 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}
+
+\end_inset
+
\SpecialChar ~
+about Overlaying and section
+\begin_inset LatexCommand \ref{sub:Functions-using-private-banks}
+
+\end_inset
+
\SpecialChar ~
-\SpecialChar ~
-\SpecialChar ~
-while(mask)
+about Functions using private banks.
\newline
-\SpecialChar ~
-\SpecialChar ~
-\SpecialChar ~
-\SpecialChar ~
-{
+
+\layout Subsection
+
+Critical Functions
+\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.
+ Note that 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
+
+
\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
}
\layout Standard
-Then, someplace in the code for the first hardware you would use
-\layout Verse
+The critical attribute maybe used with other attributes like
+\emph on
+reentrant.
+\layout Subsection
+
+Functions using private banks
+\begin_inset LatexCommand \label{sub:Functions-using-private-banks}
+
+\end_inset
+
+
+\begin_inset LatexCommand \index{bank}
+
+\end_inset
-\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
-Similarly, for the second hardware you would use
-\layout Verse
+The
+\emph on
+using
+\begin_inset LatexCommand \index{using}
+\end_inset
-\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*/
+
+\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}
+
+\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
+\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
+
+).
\newline
-bit CPOL;\SpecialChar ~
-\SpecialChar ~
-\SpecialChar ~
-\SpecialChar ~
-\SpecialChar ~
-\SpecialChar ~
-\SpecialChar ~
-\SpecialChar ~
-\SpecialChar ~
-\SpecialChar ~
-\SpecialChar ~
-/*This is a variable, let the linker allocate this one*/
+
+\emph on
+(pending: I don't think this has been done yet)
\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.
+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}
+
+\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
+
+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 Subsection
Startup Code
+\begin_inset LatexCommand \label{sub:Startup-Code}
+
+\end_inset
+
+
\begin_inset LatexCommand \index{Startup code}
\end_inset
+\layout Subsubsection
+
+MCS51/DS390 Startup Code
\layout Standard
The compiler inserts a call to the C routine
.
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 Other wise static & global variables will be initialized
- before the function main is invoked.
+ 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()
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.
-\layout Subsection
+ See also the compiler option
+\emph on
+-
+\begin_inset ERT
+status Collapsed
-Inline Assembler Code
-\begin_inset LatexCommand \index{Assembler routines}
+\layout Standard
+\backslash
+/
\end_inset
-
-\layout Standard
-
-SDCC allows the use of in-line assembler with a few restriction as regards
- labels.
- All labels defined within inline assembler code
-\emph on
-has to be
-\emph default
- of the form
-\emph on
-nnnnn$
+-no-xinit
\emph default
- where nnnn is a number less than 100 (which implies a limit of utmost 100
- inline assembler labels
+-
\emph on
-per function
+opt
\emph default
-\noun on
-)
-\noun default
-.
- It is strongly recommended that each assembly instruction (including labels)
- be placed in a separate line (as the example shows).
- When the
+
+\begin_inset LatexCommand \index{-\/-no-xinit-opt}
+
+\end_inset
+
+ and section
+\begin_inset LatexCommand \ref{sub:MCS51-variants}
+
+\end_inset
+
+\SpecialChar ~
+about MCS51-variants.
+\layout Subsubsection
+
+Z80 Startup Code
+\layout Standard
+
+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
/
\end_inset
--peep-asm
-\begin_inset LatexCommand \index{-\/-peep-asm}
+
+\series default
+\emph on
+-no-std-crt0
+\emph default
+
+\begin_inset LatexCommand \index{-\/-no-std-crt0}
\end_inset
+ and provide your own crt0.o.
+
+\layout Subsection
-\emph default
- command line option is used, the inline assembler code will be passed through
- the peephole optimizer
-\begin_inset LatexCommand \index{Peephole optimizer}
+Inline Assembler Code
+\begin_inset LatexCommand \index{Assembler routines}
\end_inset
-.
- This 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 Subsubsection
+
+A Step by Step Introduction
+\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
\family typewriter
-_asm
-\begin_inset LatexCommand \index{\_asm}
-
-\end_inset
+\size footnotesize
+unsigned char xdata at 0x7f00 buf[0x100];
+\newline
+unsigned char head,tail;
+\newline
-
+\newline
+void to_buffer( unsigned char c )
+\newline
+{
\newline
\SpecialChar ~
\SpecialChar ~
\SpecialChar ~
\SpecialChar ~
-mov\SpecialChar ~
-\SpecialChar ~
-\SpecialChar ~
-\SpecialChar ~
-\SpecialChar ~
-b,#10
-\newline
-00001$:
+if( head != tail-1 )
\newline
\SpecialChar ~
\SpecialChar ~
\SpecialChar ~
\SpecialChar ~
-djnz\SpecialChar ~
\SpecialChar ~
\SpecialChar ~
\SpecialChar ~
-b,00001$
+\SpecialChar ~
+buf[ head++ ] = c;
\newline
-_endasm
-\begin_inset LatexCommand \index{\_endasm}
-
-\end_inset
-
- ;
+}
\layout Standard
-The inline assembler code can contain any valid code understood by the assembler
-, this includes any assembler directives and comment lines.
- The compiler does not do any validation of the code within the
+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
-_asm ...
- _endasm;
+to_buffer_asm()
\family default
- keyword pair.
-
-\newline
+ 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
-\newline
-Inline assembler code cannot reference any C-Labels, however it can reference
- labels
-\begin_inset LatexCommand \index{Labels}
+_asm
+\begin_inset Quotes srd
+\end_inset
+ and
+\begin_inset Quotes sld
\end_inset
- defined by the inline assembler, e.g.:
+_endasm;
+\begin_inset Quotes srd
+\end_inset
+
+ to the beginning and the end of the function body:
\layout Verse
\family typewriter
-foo() {
+\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 ~
-/* some c code */
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+_asm
+\begin_inset LatexCommand \index{\_asm}
+
+\end_inset
+
+
\newline
\SpecialChar ~
\SpecialChar ~
\SpecialChar ~
\SpecialChar ~
-_asm
+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 ~
-; some assembler code
+dec\SpecialChar ~
+\SpecialChar ~
+a
\newline
\SpecialChar ~
\SpecialChar ~
\SpecialChar ~
\SpecialChar ~
+mov\SpecialChar ~
\SpecialChar ~
+r3,a
+\newline
\SpecialChar ~
-ljmp $0003
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+mov\SpecialChar ~
+\SpecialChar ~
+a,_head
\newline
\SpecialChar ~
\SpecialChar ~
\SpecialChar ~
\SpecialChar ~
-_endasm;
+cjne a,ar3,00106$
+\newline
+ret 00106$:
+\newline
+;buffer.c buf[ head++ ] = c;
\newline
\SpecialChar ~
\SpecialChar ~
\SpecialChar ~
\SpecialChar ~
-/* some more c code */
+mov\SpecialChar ~
+\SpecialChar ~
+r3,_head
\newline
-clabel:\SpecialChar ~
\SpecialChar ~
-/* inline assembler cannot reference this label */
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+inc\SpecialChar ~
+\SpecialChar ~
+_head
\newline
\SpecialChar ~
\SpecialChar ~
\SpecialChar ~
\SpecialChar ~
-_asm
+mov\SpecialChar ~
+\SpecialChar ~
+a,r3
\newline
\SpecialChar ~
\SpecialChar ~
\SpecialChar ~
\SpecialChar ~
-$0003: ;label (can be reference by inline assembler only)
+add\SpecialChar ~
+\SpecialChar ~
+a,#_buf
\newline
\SpecialChar ~
\SpecialChar ~
\SpecialChar ~
\SpecialChar ~
-_endasm ;
+mov\SpecialChar ~
+\SpecialChar ~
+dpl,a
\newline
\SpecialChar ~
\SpecialChar ~
\SpecialChar ~
\SpecialChar ~
-/* some more c code */
+clr\SpecialChar ~
+\SpecialChar ~
+a
\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 CANNOT be accessed by C statements.
-\layout Subsection
-
-int (16 bit)
-\begin_inset LatexCommand \index{int (16 bit)}
-
-\end_inset
-
- and long (32 bit)
-\begin_inset LatexCommand \index{long (32 bit)}
-
-\end_inset
-
- Support
-\layout Standard
-
-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 routine, all of them can be found
- in <installdir>/share/sdcc/lib.
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+addc\SpecialChar ~
+a,#(_buf >> 8)
\newline
-
-\layout Standard
-\align center
-
-\begin_inset Tabular
-<lyxtabular version="3" rows="11" columns="2">
-<features>
-<column alignment="center" valignment="top" leftline="true" width="0(null)">
-<column alignment="center" valignment="top" leftline="true" rightline="true" width="0(null)">
-<row topline="true" bottomline="true">
-<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
-\begin_inset Text
-
-\layout Standard
-
-
-\series bold
-Function
-\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
-
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+mov\SpecialChar ~
+\SpecialChar ~
+dph,a
+\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;
+\newline
+}
\layout Standard
-_mulint.c
-\end_inset
-</cell>
-<cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
-\begin_inset Text
+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:
+\layout Verse
-\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
+\family typewriter
+\size footnotesize
+unsigned char xdata at 0x7f00 buf[0x100];
+\newline
+unsigned char head,tail;
+\newline
+#define USE_ASSEMBLY (1)
+\newline
-\layout Standard
+\newline
+#ifndef USE_ASSEMBLY
+\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
-_divsint.c
-\end_inset
-</cell>
-<cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
-\begin_inset Text
+\newline
+#else
+\newline
-\layout Standard
+\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}
- 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
-\layout Standard
-
-_divuint.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
+\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 ~
+;
+\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
- 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
+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
-_modsint.c
+The assembler does not like some characters like ':' or ''' in comments.
\end_inset
-</cell>
-<cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
-\begin_inset Text
-\layout Standard
+.
+ The compiler does not do any validation of the code within the
+\family typewriter
+_asm
+\begin_inset LatexCommand \index{\_asm}
-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
-\layout Standard
+ ...
+ _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}
-_moduint.c
\end_inset
-</cell>
-<cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
-\begin_inset Text
+ has to be done manually.
+
\layout Standard
-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
+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
\layout Standard
-_mullong.c
+\backslash
+/
\end_inset
-</cell>
-<cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
-\begin_inset Text
-\layout Standard
+-
+\emph on
+peep-asm
+\begin_inset LatexCommand \index{-\/-peep-asm}
-32 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
-_divslong.c
+\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
-</cell>
-<cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
-\begin_inset Text
-\layout Standard
+.
+ 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 Subsubsection
+
+Naked Functions
+\begin_inset LatexCommand \label{sub:Naked-Functions}
- 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
-\layout Standard
-
-_divulong.c
-\end_inset
-</cell>
-<cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
-\begin_inset Text
-
-\layout Standard
-
-unsigned 32 division
-\end_inset
-</cell>
-</row>
-<row topline="true">
-<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
-\begin_inset Text
-
-\layout Standard
-
-_modslong.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{Naked functions}
- 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
-
-\layout Standard
-_modulong.c
-\end_inset
-</cell>
-<cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
-\begin_inset Text
\layout Standard
-unsigned 32 bit modulus
-\end_inset
-</cell>
-</row>
-</lyxtabular>
+A special keyword may be associated with a function declaring it as
+\emph on
+_naked
+\begin_inset LatexCommand \index{\_naked}
\end_inset
-
-\newline
-
-\layout Standard
-
-Since they are compiled as
+.
+
+\emph default
+The
\emph on
-non-reentrant
+_naked
\emph default
-
-\begin_inset LatexCommand \index{reentrant}
+ function modifier attribute prevents the compiler from generating prologue
+\begin_inset LatexCommand \index{function prologue}
\end_inset
-, interrupt
-\begin_inset LatexCommand \index{interrupt}
+ and epilogue
+\begin_inset LatexCommand \index{function epilogue}
\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
+ 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
--
-\begin_inset ERT
-status Collapsed
-
-\layout Standard
-
-\backslash
-/
-\end_inset
-
--stack-auto
-\begin_inset LatexCommand \index{-\/-stack-auto}
-
-\end_inset
-
-
+return
\emph default
- option, after which the source program will have to be compiled with
-\emph on
--
-\begin_inset ERT
-status Collapsed
-
-\layout Standard
+ 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
-\backslash
-/
-\end_inset
--int-long-rent
-\begin_inset LatexCommand \index{-\/-int-long-rent}
+\family typewriter
+volatile
+\begin_inset LatexCommand \index{volatile}
\end_inset
+ data unsigned char counter;
+\newline
-\emph default
- option.
- Notice that you don't have to call this routines directly.
- The compiler will use them automatically every time a integer operation
- is required.
-\layout Subsection
-
-Floating Point Support
-\begin_inset LatexCommand \index{Floating point support}
+\newline
+void simpleInterrupt(void) interrupt
+\begin_inset LatexCommand \index{interrupt}
\end_inset
-
-\layout Standard
-
-SDCC supports IEEE (single precision 4 bytes) floating point numbers.The
- floating point support routines are derived from gcc's floatlib.c and consists
- of the following routines:
+ 1
+\newline
+{
+\newline
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+counter++;
+\newline
+}
\newline
-\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(null)">
-<column alignment="center" valignment="top" leftline="true" rightline="true" width="0(null)">
-<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
-Function
-\end_inset
-</cell>
-<cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
-\begin_inset Text
-
-\layout Standard
+\newline
+void nakedInterrupt(void) interrupt 2 _naked
+\newline
+{
+\newline
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+_asm
+\begin_inset LatexCommand \index{\_asm}
-Description
\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 ~
+\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}
-\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
+;
+\newline
+}
\layout Standard
-
-\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
+For an 8051 target, the generated simpleInterrupt looks like:
+\layout Verse
-\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
-
+\family typewriter
+_simpleInterrupt:
+\newline
+\SpecialChar ~
+\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
+\newline
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+reti
\layout Standard
+whereas nakedInterrupt looks like:
+\layout Verse
-\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
+\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}
-\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
+ allows a more fine grained control over pushing & popping
+\begin_inset LatexCommand \index{push/pop}
-\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
+ 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 Subsubsection
-\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
-
+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
-\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 typewriter
+_asm
+\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}
-\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
+Inline assembler code cannot reference any C-Labels, however it can reference
+ labels
+\begin_inset LatexCommand \index{Labels}
-\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
+ defined by the inline assembler, e.g.:
+\layout Verse
+
+
+\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 Subsection
+
+Interfacing with Assembler Code
+\begin_inset LatexCommand \index{Assembler routines}
-\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
+\layout Subsubsection
+
+Global Registers used for Parameter Passing
+\begin_inset LatexCommand \index{Parameter passing}
-\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
+The compiler always uses the global registers
+\emph on
+DPL, DPH
+\begin_inset LatexCommand \index{DPTR, DPH, DPL}
-\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
+, B
+\begin_inset LatexCommand \index{B (register)}
+\end_inset
+
+
+\emph default
+and
+\emph on
+ ACC
+\begin_inset LatexCommand \index{ACC}
-\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
+\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
-\family roman
-\series medium
-\shape up
-\size normal
-\emph off
-\bar no
-\noun off
-\color none
-_fs2int.c
+\layout Standard
+
+\backslash
+/
\end_inset
-</cell>
-<cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
-\begin_inset Text
-\layout Standard
+-stack-auto is used) or in data / xdata memory (depending on the memory
+ model).
+
+\layout Subsubsection
+Assembler Routine(non-reentrant
+\begin_inset LatexCommand \index{reentrant}
-\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
+)
+\begin_inset LatexCommand \index{Assembler routines (non-reentrant)}
-\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
+In the following example the function c_func calls an assembler routine
+ asm_func, which takes two parameters.
+\layout Verse
-\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
+\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
+The corresponding assembler function is:
+\layout Verse
+
+
+\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 a,dpl
+\newline
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+add a,_asm_func_PARM_2
+\newline
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+mov dpl,a
+\newline
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+mov\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+dph
+\begin_inset LatexCommand \index{DPTR, DPH, DPL}
-\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
+,#0x00
+\newline
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+ret
\layout Standard
+Note here that the return values 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
-\family roman
-\series medium
-\shape up
-\size normal
-\emph off
-\bar no
-\noun off
-\color none
-convert floating point to signed long
+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
-</cell>
-</row>
-<row topline="true">
-<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
-\begin_inset Text
-\layout Standard
+dpl
+\begin_inset Quotes erd
+\end_inset
+ for One bye parameter,
+\begin_inset Quotes eld
+\end_inset
-\family roman
-\series medium
-\shape up
-\size normal
-\emph off
-\bar no
-\noun off
-\color none
-_uchar2fs.c
+dptr
+\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
+ if two bytes,
+\begin_inset Quotes eld
+\end_inset
+b,dptr
+\begin_inset Quotes erd
+\end_inset
-\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
+ for three bytes and
+\begin_inset Quotes eld
\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
+acc,b,dptr
+\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
-
-\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
+ for four bytes, the variable name for the second parameter will be _<function_n
+ame>_PARM_2.
+\newline
-\layout Standard
+\newline
+Assemble the assembler routine with the following command:
+\newline
+\newline
-\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
+\family sans
+\series bold
+asx8051 -losg asmfunc.asm
+\newline
-\layout Standard
+\newline
+\family default
+\series default
+Then compile and link the assembler routine to the C source file with the
+ following command:
+\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
-\layout Standard
+\family sans
+\series bold
+sdcc cfunc.c asmfunc.rel
+\layout Subsubsection
+Assembler Routine(reentrant
+\begin_inset LatexCommand \index{reentrant}
-\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{Assembler routines (reentrant)}
-\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
+In this case the second parameter 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 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
+\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
-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 Subsection
-
-MCS51 Memory Models
-\begin_inset LatexCommand \index{Memory model}
-
-\end_inset
-
-
-\begin_inset LatexCommand \index{MCS51 memory}
-
-\end_inset
+The corresponding assembler routine is:
+\layout Verse
-\layout Standard
-
-SDCC allows two memory models for MCS51 code, small and large.
- 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}
-
-\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 Subsection
-
-DS390 Memory Models
-\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 (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.
+\family typewriter
+.globl _asm_func
\newline
-
+_asm_func:
\newline
-In older versions of the compiler, this option was used with the MCS51 code
- generator (
-\emph on
--mmcs51
-\emph default
-).
- Now, however, the '390 has it's own code generator, selected by the
-\emph on
--mds390
-\emph default
- switch.
-
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+push _bp
\newline
-
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+mov _bp,sp
\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.
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+mov r2,dpl
\newline
-
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+mov a,_bp
\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.
-
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+clr c
\newline
-
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+add a,#0xfd
\newline
-Segments may be placed anywhere in the 4 meg address space using the usual
- -
-\begin_inset ERT
-status Collapsed
-
+\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
-\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.
+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 Subsection
-Defines Created by the Compiler
-\begin_inset LatexCommand \index{Defines created by the compiler}
+int (16 bit)
+\begin_inset LatexCommand \index{int (16 bit)}
\end_inset
-
-\layout Standard
-
-The compiler creates the following #defines
-\begin_inset LatexCommand \index{\#defines}
+ and long (32 bit)
+\begin_inset LatexCommand \index{long (32 bit)}
\end_inset
-:
+ Support
+\layout Standard
+
+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
\layout Standard
-
+\align center
\begin_inset Tabular
-<lyxtabular version="3" rows="10" columns="2">
+<lyxtabular version="3" rows="11" columns="2">
<features>
-<column alignment="center" valignment="top" leftline="true" width="0(null)">
-<column alignment="center" valignment="top" leftline="true" rightline="true" width="0(null)">
+<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
\series bold
-#define
+Function
\end_inset
</cell>
<cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
\layout Standard
-SDCC
-\begin_inset LatexCommand \index{SDCC}
-
-\end_inset
-
-
+_mulint.c
\end_inset
</cell>
<cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
\layout Standard
-this Symbol is always defined
+16 bit multiplication
\end_inset
</cell>
</row>
\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
+_divsint.c
\end_inset
</cell>
<cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
\layout Standard
-depending on the model used (e.g.: -mds390
+ signed 16 bit division (calls _divuint)
\end_inset
</cell>
</row>
\layout Standard
-__mcs51
-\begin_inset LatexCommand \index{\_\_mcs51}
-
+_divuint.c
\end_inset
+</cell>
+<cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
+\begin_inset Text
- or __ds390
-\begin_inset LatexCommand \index{\_\_ds390}
+\layout Standard
+ 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
- or __z80
-\begin_inset LatexCommand \index{\_\_z80}
-
-\end_inset
+\layout Standard
-, etc
+_modsint.c
\end_inset
</cell>
<cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
\layout Standard
-depending on the model used (e.g.
- -mz80)
+signed 16 bit modulus (calls _moduint)
\end_inset
</cell>
</row>
\layout Standard
-SDCC_STACK_AUTO
-\begin_inset LatexCommand \index{SDCC\_STACK\_AUTO}
-
-\end_inset
-
-
+_moduint.c
\end_inset
</cell>
<cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
\layout Standard
-when
-\emph on
--
-\begin_inset ERT
-status Collapsed
-
-\layout Standard
-
-\backslash
-/
-\end_inset
-
--stack-auto
-\emph default
- option is used
+unsigned 16 bit modulus
\end_inset
</cell>
</row>
\layout Standard
-SDCC_MODEL_SMALL
-\begin_inset LatexCommand \index{SDCC\_MODEL\_SMALL}
-
-\end_inset
-
-
+_mullong.c
\end_inset
</cell>
<cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
\layout Standard
-when
-\emph on
--
-\begin_inset ERT
-status Collapsed
-
-\layout Standard
-
-\backslash
-/
-\end_inset
-
--model-small
-\emph default
- is used
+32 bit multiplication
\end_inset
</cell>
</row>
\layout Standard
-SDCC_MODEL_LARGE
-\begin_inset LatexCommand \index{SDCC\_MODEL\_LARGE}
-
-\end_inset
-
-
+_divslong.c
\end_inset
</cell>
<cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
\layout Standard
-when
-\emph on
--
-\begin_inset ERT
-status Collapsed
-
-\layout Standard
-
-\backslash
-/
-\end_inset
-
--model-large
-\emph default
- is used
+ signed 32 division (calls _divulong)
\end_inset
</cell>
</row>
\layout Standard
-SDCC_USE_XSTACK
-\begin_inset LatexCommand \index{SDCC\_USE\_XSTACK}
-
-\end_inset
-
-
+_divulong.c
\end_inset
</cell>
<cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
\layout Standard
-when
-\emph on
--
-\begin_inset ERT
-status Collapsed
-
-\layout Standard
-
-\backslash
-/
-\end_inset
-
--xstack
-\emph default
- option is used
+unsigned 32 division
\end_inset
</cell>
</row>
\layout Standard
-SDCC_STACK_TENBIT
-\begin_inset LatexCommand \index{SDCC\_STACK\_TENBIT}
-
-\end_inset
-
-
+_modslong.c
\end_inset
</cell>
<cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
\layout Standard
-when
-\emph on
--mds390
-\emph default
- is used
+ signed 32 bit modulus (calls _modulong)
\end_inset
</cell>
</row>
\layout Standard
-SDCC_MODEL_FLAT24
-\begin_inset LatexCommand \index{SDCC\_MODEL\_FLAT24}
-
-\end_inset
-
-
+_modulong.c
\end_inset
</cell>
<cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
\layout Standard
-when
-\emph on
--mds390
-\emph default
- is used
+unsigned 32 bit modulus
\end_inset
</cell>
</row>
\newline
-\layout Subsection
-
-Redirecting output on Windows Shells
\layout Standard
-SDCC writes it's error messages to
-\begin_inset Quotes sld
-\end_inset
-
-standard error
-\begin_inset Quotes srd
-\end_inset
+Since they are compiled as
+\emph on
+non-reentrant
+\emph default
-.
- The windows 95/98/me shell (command or cmd) can't redirect it to a file.
- The solution is to use a reasonable shell or a helper program like redir.exe:
-\layout Standard
+\begin_inset LatexCommand \index{reentrant}
+\end_inset
-\begin_inset LatexCommand \url{http://www.cygwin.com/ml/cygwin/1999-02/msg00603.html}
+, interrupt
+\begin_inset LatexCommand \index{interrupt}
\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
+\emph on
+-
+\begin_inset ERT
+status Collapsed
\layout Standard
+\backslash
+/
+\end_inset
-\begin_inset LatexCommand \url{ftp://ftp.xraylith.wisc.edu/pub/khan/gnu-win32/mingw32/misc/redir.zip}
+-stack-auto
+\begin_inset LatexCommand \index{-\/-stack-auto}
\end_inset
+\emph default
+ option, after which the source program will have to be compiled with
+\emph on
+-
+\begin_inset ERT
+status Collapsed
+
\layout Standard
+\backslash
+/
+\end_inset
-\begin_inset LatexCommand \url{ftp://ftp.xraylith.wisc.edu/pub/khan/gnu-win32/mingw32/misc/README.redir}
+-int-long-rent
+\begin_inset LatexCommand \index{-\/-int-long-rent}
\end_inset
-\newline
+\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 Subsection
-\newline
-If you are using a windows NT/2K/XP shell, you can redirect the
-\begin_inset Quotes sld
-\end_inset
+Floating Point Support
+\begin_inset LatexCommand \index{Floating point support}
-standard error
-\begin_inset Quotes srd
\end_inset
- output to a file using
-\begin_inset Quotes sld
-\end_inset
-2>
-\begin_inset Quotes srd
-\end_inset
+\layout Standard
-.
- For example:
+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
-\series bold
+\layout Standard
+\align center
-\newline
-sdcc -c foo.c 2> foo.err
-\newline
+\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
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-To append the
-\begin_inset Quotes sld
-\end_inset
+\layout Standard
-standard error
-\begin_inset Quotes srd
-\end_inset
- output of SDCC to a file you can use
-\begin_inset Quotes sld
+\family roman
+\series medium
+\shape up
+\size normal
+\emph off
+\bar no
+\noun off
+\color none
+Function
\end_inset
-
-2>>
-\begin_inset Quotes srd
-\end_inset
-
-.
- I 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
+</cell>
+<cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
+\begin_inset Text
\layout Standard
-\backslash
-/
+Description
\end_inset
+</cell>
+</row>
+<row topline="true">
+<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
+\begin_inset Text
+\layout Standard
-\emph default
--vc
-\begin_inset LatexCommand \index{-\/-vc}
+\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
- option.
- Something like this should work:
-\newline
-
-\newline
+\layout Standard
-\series bold
-c:
-\backslash
-sdcc
-\backslash
-bin
-\backslash
-sdcc.exe -
-\series default
-\emph on
-\begin_inset ERT
-status Collapsed
+\family roman
+\series medium
+\shape up
+\size normal
+\emph off
+\bar no
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+add floating point numbers
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+</row>
+<row topline="true">
+<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
+\begin_inset Text
\layout Standard
-\backslash
-/
+
+\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
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-\series default
-\emph on
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+\shape up
+\size normal
+\emph off
+\bar no
+\noun off
+\color none
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+\end_inset
+</cell>
+</row>
+<row topline="true">
+<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
+\begin_inset Text
\layout Standard
-\backslash
-/
-\end_inset
+\family roman
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+\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
-\series bold
-\emph default
--model-large -c $(InputPath)
-\layout Section
-\pagebreak_top
-SDCC Technical Data
-\layout Subsection
+\layout Standard
-Optimizations
-\begin_inset LatexCommand \index{Optimizations}
+\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
-SDCC performs a host of standard optimizations in addition to some MCU specific
- optimizations.
-
-\layout Subsubsection
-
-Sub-expression Elimination
-\begin_inset LatexCommand \index{Subexpression elimination}
+\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
-The compiler does local and global common subexpression elimination, e.g.:
-
-\layout Verse
+\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
-\family typewriter
-i = x + y + 1;
-\newline
-j = x + y;
\layout Standard
-will be translated to
-\layout Verse
+\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
-\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.:
-\layout Verse
+\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">
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-\family typewriter
-a->b[i].c = 10;
-\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 roman
+\series medium
+\shape up
+\size normal
+\emph off
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+\end_inset
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+<cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
+\begin_inset Text
-\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 Subsubsection
-
-Dead-Code Elimination
-\begin_inset LatexCommand \index{Dead-code elimination}
+\family roman
+\series medium
+\shape up
+\size normal
+\emph off
+\bar no
+\noun off
+\color none
+convert floating point to signed char
\end_inset
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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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+\family roman
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+\end_inset
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-\SpecialChar ~
-int i;
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-\SpecialChar ~
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-\newline
-\SpecialChar ~
-\SpecialChar ~
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-/* unreachable */
-\newline
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\layout Standard
-will be changed to
-\layout Verse
+\family roman
+\series medium
+\shape up
+\size normal
+\emph off
+\bar no
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+convert floating point to unsigned int
+\end_inset
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-{
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-\SpecialChar ~
-\SpecialChar ~
-return;
-\newline
-}
-\layout Subsubsection
+\layout Standard
-Copy-Propagation
-\begin_inset LatexCommand \index{Copy propagation}
+\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
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+\end_inset
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-\SpecialChar ~
-j = i;
-\newline
-\SpecialChar ~
-\SpecialChar ~
-return j;
-\newline
-}
\layout Standard
-will be changed to
-\layout Verse
+\family roman
+\series medium
+\shape up
+\size normal
+\emph off
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+_fs2ulong.
+\family default
+\series default
+\shape default
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+\emph default
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+\end_inset
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+<cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
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\layout Standard
-Note: the dead stores created by this copy propagation will be eliminated
- by dead-code elimination.
-\layout Subsubsection
-
-Loop Optimizations
-\begin_inset LatexCommand \index{Loop optimization}
+\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
-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}
+\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
-, 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}
+\layout Standard
-\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
+\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
-\backslash
-/
-\end_inset
-
--noinduction option) or for a given function only using #pragma\SpecialChar ~
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-\begin_inset LatexCommand \index{\#pragma NOINDUCTION}
+\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
-.
-\newline
+\layout Standard
-\newline
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+\family roman
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+\bar no
+\noun off
+\color none
+convert unsigned char to floating point
+\end_inset
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+<row topline="true">
+<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
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-for (i = 0 ; i < 100 ; i ++)
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-\SpecialChar ~
-f += k + l;
\layout Standard
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-\layout Verse
+\family roman
+\series medium
+\shape up
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+\color none
+_char2fs.c
+\end_inset
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+<cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
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-\SpecialChar ~
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- address computations are also moved out of the loop.
-\newline
-
-\newline
-Strength Reduction
-\begin_inset LatexCommand \index{Strength reduction}
+\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>
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+<row topline="true">
+<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
+\begin_inset Text
-, this optimization substitutes an expression by a cheaper expression:
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-
-
-\family typewriter
-for (i=0;i < 100; i++)
-\newline
-\SpecialChar ~
-\SpecialChar ~
-ar[i*5] = i*3;
\layout Standard
-changed to
-\layout Verse
+\family roman
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+\shape up
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+_uint2fs.c
+\end_inset
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+<cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
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-\SpecialChar ~
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-\SpecialChar ~
-\SpecialChar ~
-\SpecialChar ~
-itemp2 += 3;
-\newline
-}
\layout Standard
-The more expensive multiplication
-\begin_inset LatexCommand \index{Multiplication}
+\family roman
+\series medium
+\shape up
+\size normal
+\emph off
+\bar no
+\noun off
+\color none
+convert unsigned int to floating point
\end_inset
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+<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
+\begin_inset Text
- is changed to a less expensive addition.
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+\layout Standard
-Loop Reversing
-\begin_inset LatexCommand \index{Loop reversing}
+\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
-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
+\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
- 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
+\layout Standard
-\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
+\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
-continue
-\begin_inset Quotes erd
-\end_inset
+\layout Standard
- or 'break
-\begin_inset Quotes erd
+
+\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 Itemize
+\layout Standard
-All goto's are contained within the loop.
-\layout Itemize
-No function calls within the loop.
-\layout Itemize
+\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
-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
-There are NO switch statements in the loop.
-\layout Subsubsection
+\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
-Algebraic Simplifications
\layout Standard
-SDCC does numerous algebraic simplifications, the following is a small sub-set
- of these optimizations.
-\layout Verse
+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 Subsection
+MCS51 Memory Models
+\begin_inset LatexCommand \index{Memory model}
-\family typewriter
-i = j + 0 ; /* changed to */ i = j;
+\end_inset
+
+
+\begin_inset LatexCommand \index{MCS51 memory}
+
+\end_inset
+
+
+\layout Standard
+
+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}
+
+\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 Subsection
+
+DS390 Memory Models
+\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 (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
-i /= 2; /* changed to */ i >>= 1;
+
\newline
-i = j - j ; /* changed to */ i = 0;
+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
-i = j / 1 ; /* changed to */ i = j;
+
+\newline
+Like the
+\emph on
+-
+\begin_inset ERT
+status Collapsed
+
\layout Standard
-Note the subexpressions
-\begin_inset LatexCommand \index{Subexpression}
+\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
- given above are generally introduced by macro expansions or as a result
- of copy/constant propagation.
-\layout Subsubsection
+-*-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 Subsection
-'switch' Statements
-\begin_inset LatexCommand \index{switch statement}
+Pragmas
+\begin_inset LatexCommand \index{Pragmas}
\end_inset
\layout Standard
-SDCC changes switch statements to jump tables
-\begin_inset LatexCommand \index{jump tables}
+SDCC supports the following #pragma directives.
+\layout Itemize
+
+SAVE
+\begin_inset LatexCommand \index{\#pragma SAVE}
\end_inset
- when the following conditions are true.
-
+ - this will save all current options to the SAVE/RESTORE stack.
+ See RESTORE.
\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
+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 SAVE.
+\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
+
+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
+
+NOOVERLAY
+\begin_inset LatexCommand \index{\#pragma NOOVERLAY}
+
+\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}
+
+\end_inset
+
+ - the compiler will not warn you anymore for obvious mistakes, you'r on
+ your own now ;-(
+\layout Itemize
+
+NOLOOPREVERSE
+\begin_inset LatexCommand \index{\#pragma NOLOOPREVERSE}
+
+\end_inset
+
+ - Will not do loop reversal optimization
+\layout Itemize
+
+EXCLUDE
+\begin_inset LatexCommand \index{\#pragma EXCLUDE}
+
+\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}
+
+\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}
+
+\end_inset
+
+.
+\layout Itemize
+
+NOIV
+\begin_inset LatexCommand \index{\#pragma NOIV}
+
+\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}
+
+\end_inset
-\family typewriter
-switch(i) {\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 ~
-switch (i) {
-\newline
-\SpecialChar ~
-\SpecialChar ~
-\SpecialChar ~
-case 4: ...\SpecialChar ~
-\SpecialChar ~
-\SpecialChar ~
-\SpecialChar ~
-\SpecialChar ~
-\SpecialChar ~
-\SpecialChar ~
-\SpecialChar ~
-\SpecialChar ~
-\SpecialChar ~
-\SpecialChar ~
-\SpecialChar ~
-\SpecialChar ~
-\SpecialChar ~
-\SpecialChar ~
-\SpecialChar ~
-\SpecialChar ~
-\SpecialChar ~
-\SpecialChar ~
\SpecialChar ~
+about interrupts.
+\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 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
+
+
+\family typewriter
+#pragma SAVE
+\begin_inset LatexCommand \index{\#pragma SAVE}
+
+\end_inset
+
+ \SpecialChar ~
\SpecialChar ~
\SpecialChar ~
\SpecialChar ~
\SpecialChar ~
\SpecialChar ~
\SpecialChar ~
-case 1: ...
-
+/* save the current settings */
\newline
-\SpecialChar ~
-\SpecialChar ~
-\SpecialChar ~
-case 5: ...\SpecialChar ~
-\SpecialChar ~
-\SpecialChar ~
-\SpecialChar ~
-\SpecialChar ~
-\SpecialChar ~
-\SpecialChar ~
-\SpecialChar ~
-\SpecialChar ~
-\SpecialChar ~
-\SpecialChar ~
-\SpecialChar ~
-\SpecialChar ~
-\SpecialChar ~
-\SpecialChar ~
-\SpecialChar ~
-\SpecialChar ~
-\SpecialChar ~
-\SpecialChar ~
-\SpecialChar ~
-\SpecialChar ~
+#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 ~
-case 2: ...
+ \SpecialChar ~
+ ...
\newline
\SpecialChar ~
+ \SpecialChar ~
+ /* large code */
+\newline
\SpecialChar ~
-\SpecialChar ~
-case 3: ...\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 3: ...
+ \SpecialChar ~
+ ...
\newline
-\SpecialChar ~
-\SpecialChar ~
-\SpecialChar ~
-case 6: ...\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 ~
-\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 ~
-}
+#pragma RESTORE
+\begin_inset LatexCommand \index{\#pragma RESTORE}
+
+\end_inset
+
+ /* turn the optimizations back on */
\layout Standard
-Both the above switch statements will be implemented using a jump-table.
-\end_deeper
-\layout Itemize
+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 Subsection
+
+Defines Created by the Compiler
+\begin_inset LatexCommand \index{Defines created by the compiler}
+
+\end_inset
-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
+The compiler creates the following #defines
+\begin_inset LatexCommand \index{\#defines}
+\end_inset
-\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 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
+\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
-\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
-}
\layout Standard
-and
-\layout Verse
+\series bold
+#define
+\end_inset
+</cell>
+<cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
+\begin_inset Text
-\family typewriter
-switch (i) {
-\newline
-\SpecialChar ~
-\SpecialChar ~
-case 9: \SpecialChar ~
-...
-
-\newline
-\SpecialChar ~
-\SpecialChar ~
-case 10: ...
-
-\newline
-\SpecialChar ~
-\SpecialChar ~
-case 11: ...
-
-\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.
-\layout Subsubsection
-
-Bit-shifting Operations
-\begin_inset LatexCommand \index{Bit shifting}
+\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
-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
+SDCC
+\begin_inset LatexCommand \index{SDCC}
+\end_inset
-\family typewriter
-unsigned char i;
-\newline
-...
-\newline
-i>>= 4;
-\newline
-...
-\layout Standard
+\end_inset
+</cell>
+<cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
+\begin_inset Text
-generates the following code:
-\layout Verse
+\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
-\family typewriter
-mov a,_i
-\newline
-swap a
-\newline
-anl a,#0x0f
-\newline
-mov _i,a
\layout Standard
-In general SDCC will never setup a loop if the shift count is known.
- Another example:
-\layout Verse
+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
-\family typewriter
-unsigned int i;
-\newline
-...
-
-\newline
-i >>= 9;
-\newline
-...
\layout Standard
-will generate:
-\layout Verse
+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
+
+ or __ds390
+\begin_inset LatexCommand \index{\_\_ds390}
+
+\end_inset
+
+ or __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
-\family typewriter
-mov a,(_i + 1)
-\newline
-mov (_i + 1),#0x00
-\newline
-clr c
-\newline
-rrc a
-\newline
-mov _i,a
\layout Standard
-Note that SDCC stores numbers in little-endian format (i.e.
- lowest order first).
-\layout Subsubsection
+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
-Bit-rotation
-\begin_inset LatexCommand \index{Bit rotation}
+\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
-A special case of the bit-shift operation is bit rotation, SDCC recognizes
- the following expression to be a left bit-rotation:
-\layout Verse
+when
+\emph on
+-
+\begin_inset ERT
+status Collapsed
+\layout Standard
-\family typewriter
-unsigned char i;
-\newline
-...
-
-\newline
-i = ((i << 1) | (i >> 7));
-\family default
+\backslash
+/
+\end_inset
-\newline
+-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
-\family typewriter
-...
\layout Standard
-will generate the following code:
-\layout Verse
+SDCC_MODEL_SMALL
+\begin_inset LatexCommand \index{SDCC\_MODEL\_SMALL}
+
+\end_inset
-\family typewriter
-mov a,_i
-\newline
-rl a
-\newline
-mov _i,a
+\end_inset
+</cell>
+<cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
+\begin_inset Text
+
\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
+when
+\emph on
+-
+\begin_inset ERT
+status Collapsed
+\layout Standard
-\family typewriter
-i = ((i >> 7) | (i << 1)); /* left-bit rotation */
-\layout Subsubsection
+\backslash
+/
+\end_inset
-Highest Order Bit
-\begin_inset LatexCommand \index{Highest Order Bit}
+-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_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
-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.:
-\layout Verse
+when
+\emph on
+-
+\begin_inset ERT
+status Collapsed
+\layout Standard
-\family typewriter
-unsigned int gint;
-\newline
+\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
-\newline
-foo () {
-\newline
-unsigned char hob;
-\newline
-\SpecialChar ~
-\SpecialChar ~
-...
-
-\newline
-\SpecialChar ~
-\SpecialChar ~
-hob = (gint >> 15) & 1;
-\newline
-\SpecialChar ~
-\SpecialChar ~
-..
-
-\newline
-}
\layout Standard
-will generate the following code:
-\layout Verse
+SDCC_USE_XSTACK
+\begin_inset LatexCommand \index{SDCC\_USE\_XSTACK}
+\end_inset
-\family typewriter
-\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 ~
- a,(_gint + 1)
-\newline
-000C 33\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 ~
- rlc\SpecialChar ~
- a
-\newline
-000D E4\SpecialChar ~
-\SpecialChar ~
-\SpecialChar ~
-\SpecialChar ~
-\SpecialChar ~
-\SpecialChar ~
-\SpecialChar ~
-\SpecialChar ~
-\SpecialChar ~
-\SpecialChar ~
-\SpecialChar ~
-\SpecialChar ~
-\SpecialChar ~
-\SpecialChar ~
-\SpecialChar ~
-\SpecialChar ~
-\SpecialChar ~
-\SpecialChar ~
- 64\SpecialChar ~
-\SpecialChar ~
-\SpecialChar ~
-\SpecialChar ~
-\SpecialChar ~
-\SpecialChar ~
-\SpecialChar ~
-\SpecialChar ~
- clr\SpecialChar ~
- a
-\newline
-000E 13\SpecialChar ~
-\SpecialChar ~
-\SpecialChar ~
-\SpecialChar ~
-\SpecialChar ~
-\SpecialChar ~
-\SpecialChar ~
-\SpecialChar ~
-\SpecialChar ~
-\SpecialChar ~
-\SpecialChar ~
-\SpecialChar ~
-\SpecialChar ~
-\SpecialChar ~
-\SpecialChar ~
-\SpecialChar ~
-\SpecialChar ~
-\SpecialChar ~
- 65\SpecialChar ~
-\SpecialChar ~
-\SpecialChar ~
-\SpecialChar ~
-\SpecialChar ~
-\SpecialChar ~
-\SpecialChar ~
-\SpecialChar ~
- rrc\SpecialChar ~
- a
-\newline
-000F F5*02\SpecialChar ~
-\SpecialChar ~
-\SpecialChar ~
-\SpecialChar ~
-\SpecialChar ~
-\SpecialChar ~
-\SpecialChar ~
-\SpecialChar ~
-\SpecialChar ~
-\SpecialChar ~
-\SpecialChar ~
-\SpecialChar ~
-\SpecialChar ~
-\SpecialChar ~
-\SpecialChar ~
- 66\SpecialChar ~
-\SpecialChar ~
-\SpecialChar ~
-\SpecialChar ~
-\SpecialChar ~
-\SpecialChar ~
-\SpecialChar ~
-\SpecialChar ~
- mov\SpecialChar ~
- _foo_hob_1_1,a
-\layout Standard
-
-Variations of this case however will
-\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).
- 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);
-\layout Standard
-
-will still be recognized.
-\layout Subsubsection
-
-Peephole Optimizer
-\begin_inset LatexCommand \index{Peephole optimizer}
\end_inset
-
+</cell>
+<cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
+\begin_inset Text
\layout Standard
-The compiler uses a rule based, pattern matching and re-writing mechanism
- for peep-hole optimization.
- It is inspired by
-\emph on
-copt
-\emph default
- a peep-hole optimizer by Christopher W.
- Fraser (cwfraser@microsoft.com).
- A default set of rules are compiled into the compiler, additional rules
- may be added with the
+when
\emph on
-
\begin_inset ERT
/
\end_inset
--peep-file
-\begin_inset LatexCommand \index{-\/-peep-file}
-
-\end_inset
-
- <filename>
+-xstack
\emph default
- option.
- The rule language is best illustrated with examples.
-\layout Verse
-
+ option 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
-replace {
-\newline
-\SpecialChar ~
-\SpecialChar ~
-mov %1,a
-\newline
-\SpecialChar ~
-\SpecialChar ~
-mov a,%1
-\newline
-} by {
-\newline
-\SpecialChar ~
-\SpecialChar ~
-mov %1,a
-\newline
-}
\layout Standard
-The above rule will change the following assembly
-\begin_inset LatexCommand \index{Assembler routines}
+SDCC_STACK_TENBIT
+\begin_inset LatexCommand \index{SDCC\_STACK\_TENBIT}
\end_inset
- sequence:
-\layout Verse
+
+\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
-\family typewriter
-mov r1,a
-\newline
-mov a,r1
\layout Standard
-to
-\layout Verse
+SDCC_MODEL_FLAT24
+\begin_inset LatexCommand \index{SDCC\_MODEL\_FLAT24}
+
+\end_inset
-\family typewriter
-mov r1,a
+\end_inset
+</cell>
+<cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
+\begin_inset Text
+
\layout Standard
-Note: All occurrences of a
+when
\emph on
-%n
+-mds390
\emph default
- (pattern variable) must denote the same string.
- With the above rule, the assembly sequence:
-\layout Verse
+ is used
+\end_inset
+</cell>
+</row>
+</lyxtabular>
+
+\end_inset
-\family typewriter
-mov r1,a
\newline
-mov a,r2
+
+\layout Section
+\pagebreak_top
+Debugging with SDCDB
+\begin_inset LatexCommand \index{sdcdb}
+
+\end_inset
+
+
\layout Standard
-will remain unmodified.
-\newline
+SDCC is distributed with a source level debugger
+\begin_inset LatexCommand \index{Debugger}
-\newline
-Other special case optimizations may be added by the user (via
-\emph on
--
+\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 available on Unix platforms only.
+\layout Subsection
+
+Compiling for Debugging
+\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 Subsection
+
+How the Debugger Works
+\layout Standard
+
+When the -
\begin_inset ERT
status Collapsed
/
\end_inset
--peep-file option
-\emph default
-).
- E.g.
- some variants of the 8051 MCU allow only
-\family typewriter
-ajmp
-\family default
- and
-\family typewriter
-acall
-\family default
-.
- The following two rules will change all
-\family typewriter
-ljmp
-\family default
- and
-\family typewriter
-lcall
-\family default
- to
-\family typewriter
-ajmp
-\family default
- and
-\family typewriter
-acall
-\layout Verse
+-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 Subsection
+Starting the Debugger
+\layout Standard
-\family typewriter
-replace { lcall %1 } by { acall %1 }
+The debugger can be started using the following command line.
+ (Assume the file you are debugging has the file name foo).
\newline
-replace { ljmp %1 } by { ajmp %1 }
-\layout Standard
-The
-\emph on
-inline-assembler code
-\emph default
- is also passed through the peep hole optimizer, thus the peephole optimizer
- can also be used as an assembly level macro expander.
- The rules themselves are MCU dependent whereas the rule language infra-structur
-e is MCU independent.
- Peephole optimization rules for other MCU can be easily programmed using
- the rule language.
\newline
+\family sans
+\series bold
+sdcdb foo
\newline
-The syntax for a rule is as follows:
-\layout Verse
+\family default
+\series default
-\family typewriter
-rule := replace [ restart ] '{' <assembly sequence> '
-\backslash
-n'
-\newline
-\SpecialChar ~
- \SpecialChar ~
- \SpecialChar ~
- \SpecialChar ~
- \SpecialChar ~
- \SpecialChar ~
- \SpecialChar ~
- \SpecialChar ~
- \SpecialChar ~
- \SpecialChar ~
- \SpecialChar ~
- \SpecialChar ~
- \SpecialChar ~
- \SpecialChar ~
- '}' by '{' '
-\backslash
-n'
-\newline
-\SpecialChar ~
- \SpecialChar ~
- \SpecialChar ~
- \SpecialChar ~
- \SpecialChar ~
- \SpecialChar ~
- \SpecialChar ~
- \SpecialChar ~
- \SpecialChar ~
- \SpecialChar ~
- \SpecialChar ~
- \SpecialChar ~
- \SpecialChar ~
- \SpecialChar ~
- \SpecialChar ~
- \SpecialChar ~
- <assembly sequence> '
-\backslash
-n'
\newline
-\SpecialChar ~
- \SpecialChar ~
- \SpecialChar ~
- \SpecialChar ~
- \SpecialChar ~
- \SpecialChar ~
- \SpecialChar ~
- \SpecialChar ~
- \SpecialChar ~
- \SpecialChar ~
- \SpecialChar ~
- \SpecialChar ~
- \SpecialChar ~
- \SpecialChar ~
- '}' [if <functionName> ] '
-\backslash
-n'
-\layout Standard
+The debugger will look for the following files.
+\layout Itemize
-<assembly sequence> := assembly instruction (each instruction including
- labels must be on a separate line).
-\newline
+foo.c - the source file.
+\layout Itemize
-\newline
-The optimizer will apply to the rules one by one from the top in the sequence
- of their appearance, it will terminate when all rules are exhausted.
- If the 'restart' option is specified, then the optimizer will start matching
- the rules again from the top, this option for a rule is expensive (performance)
-, it is intended to be used in situations where a transformation will trigger
- the same rule again.
- An example of this (not a good one, it has side effects) is the following
- rule:
-\layout Verse
+foo.cdb - the debugger symbol information file.
+\layout Itemize
+foo.ihx - the Intel hex format
+\begin_inset LatexCommand \index{Intel hex format}
-\family typewriter
-replace restart {
-\newline
-\SpecialChar ~
-\SpecialChar ~
-pop %1
-\newline
-\SpecialChar ~
-\SpecialChar ~
-push %1 } by {
-\newline
-\SpecialChar ~
-\SpecialChar ~
-; nop
-\newline
-}
-\layout Standard
+\end_inset
-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
- be eliminated, i.e.:
-\layout Verse
+ object file.
+\layout Subsection
+Command Line Options.
+\layout Itemize
+
+-
+\begin_inset ERT
+status Collapsed
-\family typewriter
-pop ar1
-\newline
-pop ar2
-\newline
-push ar2
-\newline
-push ar1
\layout Standard
-would result in:
-\layout Verse
+\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
-\family typewriter
-pop ar1
-\newline
-; nop
-\newline
-push ar1
\layout Standard
+\backslash
+/
+\end_inset
-\emph on
-with
-\emph default
- the restart option the rule will be applied again to the resulting code
- and then all the pop-push pairs will be eliminated to yield:
-\layout Verse
-
-
-\family typewriter
-; nop
-\newline
-; nop
-\layout Standard
-
-A conditional function can be attached to a rule.
- Attaching rules are somewhat more involved, let me illustrate this with
- an example.
-\layout Verse
-
-
-\family typewriter
-replace {
-\newline
-\SpecialChar ~
- \SpecialChar ~
- \SpecialChar ~
-ljmp %5
-\newline
-%2:
-\newline
-} by {
-\newline
-\SpecialChar ~
- \SpecialChar ~
- \SpecialChar ~
-sjmp %5
-\newline
-%2:
-\newline
-} if labelInRange
-\layout Standard
-
-The optimizer does a look-up of a function name table defined in function
-
-\emph on
-callFuncByName
-\emph default
- in the source file SDCCpeeph.c, with the name
-\emph on
-labelInRange
-\emph default
-.
- If it finds a corresponding entry the function is called.
- Note there can be no parameters specified for these functions, in this
- case the use of
-\emph on
-%5
-\emph default
- is crucial, since the function
-\emph on
-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.
- 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 also 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 -
+-directory option should be -
\begin_inset ERT
status Collapsed
/
\end_inset
--peep-file option.
-\layout Subsection
+-directory=/home/src1:/home/src2.
+ Note there can be no spaces in the option.
+
+\layout Itemize
-Pragmas
-\begin_inset LatexCommand \index{Pragmas}
+-cd <directory> - change to the <directory>.
+\layout Itemize
-\end_inset
+-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
-\layout Standard
+-X <Clock frequency > this options is passed to the simulator please see
+ the simulator docs for details.
+\layout Itemize
-SDCC supports the following #pragma directives.
+-s <serial port file> passed to simulator see the simulator docs for details.
\layout Itemize
-SAVE
-\begin_inset LatexCommand \index{\#pragma SAVE}
+-S <serial in,out> passed to simulator see the simulator docs for details.
+\layout Subsection
-\end_inset
+Debugger Commands.
+\layout Standard
- - this will save all current options to the SAVE/RESTORE stack.
- See RESTORE.
-\layout Itemize
+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*
-RESTORE
-\begin_inset LatexCommand \index{\#pragma RESTORE}
+break [line | file:line | function | file:function]
+\layout Standard
-\end_inset
+Set breakpoint at specified line or function:
+\newline
- - 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
+\newline
-NOGCSE
-\begin_inset LatexCommand \index{\#pragma NOGCSE}
+\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*
-\end_inset
+clear [line | file:line | function | file:function ]
+\layout Standard
- - will stop global subexpression elimination.
-\layout Itemize
+Clear breakpoint at specified line or function:
+\newline
-NOINDUCTION
-\begin_inset LatexCommand \index{\#pragma NOINDUCTION}
+\newline
-\end_inset
+\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*
- - will stop loop induction optimizations.
-\layout Itemize
+continue
+\layout Standard
-NOJTBOUND
-\begin_inset LatexCommand \index{\#pragma NOJTBOUND}
+Continue program being debugged, after breakpoint.
+\layout Subsubsection*
-\end_inset
+finish
+\layout Standard
- - will not generate code for boundary value checking, when switch statements
- are turned into jump-tables.
-\layout Itemize
+Execute till the end of the current function.
+\layout Subsubsection*
-NOOVERLAY
-\begin_inset LatexCommand \index{\#pragma NOOVERLAY}
+delete [n]
+\layout Standard
-\end_inset
+Delete breakpoint number 'n'.
+ If used without any option clear ALL user defined break points.
+\layout Subsubsection*
- - the compiler will not overlay the parameters and local variables of a
- function.
+info [break | stack | frame | registers ]
\layout Itemize
-LESS_PEDANTIC
-\begin_inset LatexCommand \index{\#pragma LESS\_PEDANTIC}
+info break - list all breakpoints
+\layout Itemize
-\end_inset
+info stack - show the function call stack.
+\layout Itemize
- - the compiler will not warn you anymore for obvious mistakes, you'r on
- your own now ;-(
+info frame - show information about the current execution frame.
\layout Itemize
-NOLOOPREVERSE
-\begin_inset LatexCommand \index{\#pragma NOLOOPREVERSE}
+info registers - show content of all registers.
+\layout Subsubsection*
-\end_inset
+step
+\layout Standard
- - Will not do loop reversal optimization
-\layout Itemize
+Step program until it reaches a different source line.
+\layout Subsubsection*
-EXCLUDE
-\begin_inset LatexCommand \index{\#pragma EXCLUDE}
+next
+\layout Standard
-\end_inset
+Step program, proceeding through subroutine calls.
+\layout Subsubsection*
- NONE | {acc[,b[,dpl[,dph]]] - The exclude pragma disables generation of
- pair of push/pop
-\begin_inset LatexCommand \index{push/pop}
+run
+\layout Standard
-\end_inset
+Start debugged program.
+\layout Subsubsection*
- instruction in ISR function (using interrupt
-\begin_inset LatexCommand \index{interrupt}
+ptype variable
+\layout Standard
-\end_inset
+Print type information of the variable.
+\layout Subsubsection*
- 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}
+print variable
+\layout Standard
-\end_inset
+print value of variable.
+\layout Subsubsection*
-.
-\layout Itemize
+file filename
+\layout Standard
-NOIV
-\begin_inset LatexCommand \index{\#pragma NOIV}
+load the given file name.
+ Note this is an alternate method of loading file for debugging.
+\layout Subsubsection*
-\end_inset
+frame
+\layout Standard
- - 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).
-\layout Itemize
+print information about current frame.
+\layout Subsubsection*
-CALLEE-SAVES
-\begin_inset LatexCommand \index{\#pragma CALLEE-SAVES}
+set srcmode
+\layout Standard
-\end_inset
+Toggle between C source & assembly source.
+\layout Subsubsection*
+! simulator command
+\layout Standard
-\begin_inset LatexCommand \index{function prologue}
+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
+quit.
+\layout Standard
- 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
+"Watch me now.
+ Iam going Down.
+ My name is Bobby Brown"
+\layout Subsection
-\layout Standard
+Interfacing with XEmacs
+\begin_inset LatexCommand \index{XEmacs}
-\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}
+
+\begin_inset LatexCommand \index{Emacs}
\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-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
+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
-#pragma SAVE
-\begin_inset LatexCommand \index{\#pragma SAVE}
-
-\end_inset
+(load-file sdcdbsrc.el)
+\family default
- /* save the current settings */
\newline
-#pragma NOGCSE
-\begin_inset LatexCommand \index{\#pragma NOGCSE}
-\end_inset
+\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
- /* turnoff global subexpression elimination */
\newline
-#pragma NOINDUCTION
-\begin_inset LatexCommand \index{\#pragma NOINDUCTION}
-\end_inset
+\family sans
+\series bold
+ESC-x sdcdbsrc
+\family default
+\series default
- /* turn off induction optimizations */
-\newline
-int foo ()
-\newline
-{
-\newline
-\SpecialChar ~
- \SpecialChar ~
- ...
-
\newline
-\SpecialChar ~
- \SpecialChar ~
- /* large code */
+
\newline
-\SpecialChar ~
- \SpecialChar ~
- ...
+You will prompted to enter the file name to be debugged.
\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 Subsection
-
-Library Routines
-\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 Comment
-
-license statements for the libraries are missing
-\layout Subsection
-
-Interfacing with Assembly Routines
-\begin_inset LatexCommand \index{Assembler routines}
-
-\end_inset
-
-
-\layout Subsubsection
-
-Global Registers used for Parameter Passing
-\begin_inset LatexCommand \index{Parameter passing}
-
-\end_inset
-
-
-\layout Standard
-
-The compiler always uses the global registers
-\emph on
-DPL, DPH
-\begin_inset LatexCommand \index{DPTR, DPH, DPL}
-
-\end_inset
-
-, B
-\begin_inset LatexCommand \index{B (register)}
-
-\end_inset
-
-\emph default
-and
-\emph on
- ACC
-\begin_inset LatexCommand \index{ACC}
-
-\end_inset
+\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
-\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
+sdcdbsrc-frequency '11059200
+\layout Itemize
+sdcdbsrc-serial nil
\layout Standard
-\backslash
-/
-\end_inset
-
--stack-auto is used) or in the internal / external ram (depending on the
- memory model).
-
-\layout Subsubsection
-
-Assembler Routine(non-reentrant
-\begin_inset LatexCommand \index{reentrant}
-
-\end_inset
-
-)
-\begin_inset LatexCommand \index{Assembler routines (non-reentrant)}
-
-\end_inset
-
-
+The following is a list of key mapping for the debugger interface.
\layout Standard
-In the following example the function c_func calls an assembler routine
- asm_func, which takes two parameters.
-\layout Verse
-
+\SpecialChar ~
\family typewriter
-extern int asm_func(unsigned char, unsigned char);
-\newline
\newline
-int c_func (unsigned char i, unsigned char j)
-\newline
-{
+;; Current Listing ::
\newline
+;;key\SpecialChar ~
\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 function is:
-\layout Verse
-
-
-\family typewriter
-.globl _asm_func_PARM_2
-\newline
\SpecialChar ~
\SpecialChar ~
\SpecialChar ~
\SpecialChar ~
\SpecialChar ~
\SpecialChar ~
+binding\SpecialChar ~
\SpecialChar ~
\SpecialChar ~
-.globl _asm_func
-\newline
\SpecialChar ~
\SpecialChar ~
\SpecialChar ~
\SpecialChar ~
\SpecialChar ~
\SpecialChar ~
-.area OSEG
-\newline
-_asm_func_PARM_2:
-\newline
\SpecialChar ~
\SpecialChar ~
\SpecialChar ~
\SpecialChar ~
\SpecialChar ~
\SpecialChar ~
-.ds 1
-\newline
\SpecialChar ~
\SpecialChar ~
\SpecialChar ~
+Comment
+\newline
+;;---\SpecialChar ~
\SpecialChar ~
\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 ~
\SpecialChar ~
\SpecialChar ~
-add a,_asm_func_PARM_2
-\newline
\SpecialChar ~
\SpecialChar ~
\SpecialChar ~
\SpecialChar ~
\SpecialChar ~
\SpecialChar ~
-mov dpl,a
-\newline
\SpecialChar ~
\SpecialChar ~
\SpecialChar ~
\SpecialChar ~
\SpecialChar ~
\SpecialChar ~
+--------
+\newline
+;;
+\newline
+;; n\SpecialChar ~
\SpecialChar ~
\SpecialChar ~
-mov\SpecialChar ~
\SpecialChar ~
\SpecialChar ~
\SpecialChar ~
-dpl
-\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 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 Subsubsection
-
-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 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
+ sdcdb-next-from-src\SpecialChar ~
\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:
+\SpecialChar ~
+SDCDB next command
\newline
+;; b\SpecialChar ~
\SpecialChar ~
\SpecialChar ~
\SpecialChar ~
\SpecialChar ~
-push _bp
-\newline
\SpecialChar ~
\SpecialChar ~
\SpecialChar ~
\SpecialChar ~
-mov _bp,sp
-\newline
\SpecialChar ~
\SpecialChar ~
\SpecialChar ~
\SpecialChar ~
-mov r2,dpl
-\newline
\SpecialChar ~
+ sdcdb-back-from-src\SpecialChar ~
\SpecialChar ~
\SpecialChar ~
\SpecialChar ~
-mov a,_bp
-\newline
\SpecialChar ~
\SpecialChar ~
\SpecialChar ~
\SpecialChar ~
-clr c
-\newline
\SpecialChar ~
\SpecialChar ~
+SDCDB back command
+\newline
+;; c\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 ~
+ sdcdb-cont-from-src\SpecialChar ~
\SpecialChar ~
-mov r1,a
-\newline
\SpecialChar ~
\SpecialChar ~
\SpecialChar ~
\SpecialChar ~
-mov a,@r0
-\newline
\SpecialChar ~
\SpecialChar ~
\SpecialChar ~
\SpecialChar ~
-add a,r2
+SDCDB continue command
\newline
+;; s\SpecialChar ~
\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 ~
+ sdcdb-step-from-src\SpecialChar ~
\SpecialChar ~
\SpecialChar ~
\SpecialChar ~
-pop _bp
-\newline
\SpecialChar ~
\SpecialChar ~
\SpecialChar ~
\SpecialChar ~
-ret
-\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 Subsection
-
-External Stack
-\begin_inset LatexCommand \index{stack}
-
-\end_inset
-
-
-\begin_inset LatexCommand \index{External stack}
-
-\end_inset
-
-
-\layout Standard
-
-The external stack 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
-/
-\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 -
-\begin_inset ERT
-status Collapsed
-
-\layout Standard
-
-\backslash
-/
-\end_inset
-
--stack-auto 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 Subsection
-
-ANSI-Compliance
-\begin_inset LatexCommand \index{ANSI-compliance}
-
-\end_inset
-
-
-\layout Standard
-
-Deviations from the compliance:
-\layout Itemize
-
-functions are not always reentrant.
-\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.:
-\begin_deeper
-\layout Verse
-
-
-\family typewriter
-struct s { ...
- };
-\newline
-struct s s1, s2;
-\newline
-foo()
-\newline
-{
+\SpecialChar ~
+\SpecialChar ~
+SDCDB step command
\newline
+;; ?\SpecialChar ~
\SpecialChar ~
\SpecialChar ~
\SpecialChar ~
\SpecialChar ~
-...
-
-\newline
\SpecialChar ~
\SpecialChar ~
\SpecialChar ~
\SpecialChar ~
-s1 = s2 ; /* is invalid in SDCC although allowed in ANSI */
-\newline
\SpecialChar ~
\SpecialChar ~
\SpecialChar ~
\SpecialChar ~
-...
-
-\newline
-}
-\newline
-struct s foo1 (struct s parms) /* invalid in SDCC although allowed in ANSI
- */
-\newline
-{
-\newline
\SpecialChar ~
+ sdcdb-whatis-c-sexp\SpecialChar ~
\SpecialChar ~
\SpecialChar ~
\SpecialChar ~
-struct s rets;
-\newline
\SpecialChar ~
\SpecialChar ~
\SpecialChar ~
\SpecialChar ~
-...
-
+\SpecialChar ~
+\SpecialChar ~
+SDCDB ptypecommand for data at
\newline
+;;\SpecialChar ~
\SpecialChar ~
\SpecialChar ~
\SpecialChar ~
\SpecialChar ~
-return rets;/* is invalid in SDCC although allowed in ANSI */
-\newline
-}
-\end_deeper
-\layout Itemize
-
-'long long
-\begin_inset LatexCommand \index{long long (not supported)}
-
-\end_inset
-
-' (64 bit integers
-\begin_inset LatexCommand \index{int (64 bit) (not supported)}
-
-\end_inset
-
-) not supported.
-\layout Itemize
-
-'double
-\begin_inset LatexCommand \index{double (not supported)}
-
-\end_inset
-
-' precision floating point
-\begin_inset LatexCommand \index{Floating point support}
-
-\end_inset
-
-not supported.
-\layout Itemize
-
-No support for setjmp and longjmp (for now).
-\layout Itemize
-
-Old K&R style
-\begin_inset LatexCommand \index{K\&R style}
-
-\end_inset
-
- function declarations are NOT allowed.
-\begin_deeper
-\layout Verse
-
-
-\family typewriter
-foo(i,j) /* this old style of function declarations */
-\newline
-int i,j; /* are valid in ANSI but not valid in SDCC */
-\newline
-{
-\newline
\SpecialChar ~
\SpecialChar ~
\SpecialChar ~
\SpecialChar ~
-...
-
-\newline
-}
-\end_deeper
-\layout Itemize
-
-functions declared as pointers must be dereferenced during the call.
-\begin_deeper
-\layout Verse
-
-
-\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
-\layout Subsection
-
-Cyclomatic Complexity
-\begin_inset LatexCommand \index{Cyclomatic complexity}
-
-\end_inset
-
-
-\layout Standard
-
-Cyclomatic complexity of a function is defined as the number of independent
- paths the program can take during execution of the function.
- This is an important number since it defines the number test cases you
- have to generate to validate the function.
- The accepted industry standard for complexity number is 10, if the cyclomatic
- complexity reported by SDCC exceeds 10 you should think about simplification
- of the function logic.
- Note that the complexity level is not related to the number of lines of
- code in a function.
- Large functions can have low complexity, and small functions can have large
- complexity levels.
-
-\newline
-
-\newline
-SDCC uses the following formula to compute the complexity:
-\newline
-
-\layout Standard
-
-complexity = (number of edges in control flow graph) - (number of nodes
- in control flow graph) + 2;
-\newline
-
-\newline
-Having said that the industry standard is 10, you should be aware that in
- some cases it be may unavoidable to have a complexity level of less than
- 10.
- For example if you have switch statement with more than 10 case labels,
- each case label adds one to the complexity level.
- The complexity level is by no means an absolute measure of the algorithmic
- complexity of the function, it does however provide a good starting point
- for which functions you might look at for further optimization.
-\layout Section
-\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'.
-\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.
-\layout Itemize
-
-NEVER jump into a LOOP.
-\layout Itemize
-
-Declare the variables to be local 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 ~
\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 ;
+\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 ~
+ buffer point
\newline
+;; x\SpecialChar ~
\SpecialChar ~
\SpecialChar ~
\SpecialChar ~
\SpecialChar ~
-....
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+ sdcdbsrc-delete\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+SDCDB Delete all breakpoints if no arg
\newline
-}
-\layout Standard
-
-It would substantially reduce the code generated (future versions of the
+;;\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 ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+given or delete arg (C-u arg x)
+\newline
+;; m\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+ sdcdbsrc-frame\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+SDCDB Display current frame if no arg,
+\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 ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+given or display frame arg
+\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 ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+buffer point
+\newline
+;; !\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
+;; p\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+ sdcdb-print-c-sexp\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+SDCDB print command for data at
+\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 ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+ buffer point
+\newline
+;; g\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
+;; t\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 ~
+\SpecialChar ~
+Toggles Sdcdbsrc mode (turns it off)
+\newline
+;;
+\newline
+;; C-c C-f\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+ sdcdb-finish-from-src\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+SDCDB finish command
+\newline
+;;
+\newline
+;; C-x SPC\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+ sdcdb-break\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+Set break for line with point
+\newline
+;; ESC t\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 ~
+\SpecialChar ~
+Toggle Sdcdbsrc mode
+\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
+\newline
+;;
+\newline
+
+\layout Section
+\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'.
+\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.
+\layout Itemize
+
+NEVER jump into a LOOP.
+\layout Itemize
+
+Declare the variables to be local 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 ~
+\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 ~
+....
+\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 Subsection
Notes on MCS51 memory
- 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 variables and,
+- Bytes 20-2F - 16 bytes to hold 128 bit
+\begin_inset LatexCommand \index{bit}
+
+\end_inset
+
+ variables and,
\newline
- Bytes 30-7F - 80 bytes for general purpose use.
\newline
\emph on
idata
\emph default
+
+\begin_inset LatexCommand \index{idata}
+
+\end_inset
+
).
Furthermore, some chips may have some built in external memory (
\emph on
xdata
\emph default
+
+\begin_inset LatexCommand \index{xdata}
+
+\end_inset
+
) which should not be confused with the internal, directly addressable RAM
memory (
\emph on
data
\emph default
+
+\begin_inset LatexCommand \index{data}
+
+\end_inset
+
).
- Usually this built in
+ Sometimes this built in
\emph on
xdata
\emph default
\end_inset
included in the distribution
-\newline
-
\layout Standard
\align center
\end_inset
-\newline
-
\layout Standard
\align center
\begin_inset Tabular
-<lyxtabular version="3" rows="7" columns="3">
+<lyxtabular version="3" rows="8" columns="3">
<features>
<column alignment="center" valignment="top" leftline="true" width="0pt">
-<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">
\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://digilander.libero.it/fbradasc/FLP5.html}
+
+\end_inset
+
+
\end_inset
</cell>
</row>
\end_inset
-
+ (Unix only)
\end_inset
</cell>
<cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
\layout Subsection
Related documentation / recommended reading
-\newline
-
\layout Standard
\align center
<lyxtabular version="3" rows="5" columns="3">
<features>
<column alignment="center" valignment="top" leftline="true" width="0pt">
-<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">
\layout Section
\pagebreak_top
-Retargetting for other MCUs.
-\layout Standard
+Support
+\begin_inset LatexCommand \index{Support}
-The issues for retargetting the compiler are far too numerous to be covered
- by this document.
- What follows is a brief description of each of the seven phases of the
- compiler and its MCU dependency.
-\layout Itemize
+\end_inset
-Parsing the source and building the annotated parse tree.
- This phase is largely MCU independent (except for the language extensions).
- Syntax & semantic checks are also done in this phase, along with some initial
- optimizations like back patching labels and the pattern matching optimizations
- like bit-rotation etc.
-\layout Itemize
-The second phase involves generating an intermediate code which can be easy
- manipulated during the later phases.
- This phase is entirely MCU independent.
- The intermediate code generation assumes the target machine has unlimited
- number of registers, and designates them with the name iTemp.
- The compiler can be made to dump a human readable form of the code generated
- by using the -
-\begin_inset ERT
-status Collapsed
+\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
-\backslash
-/
-\end_inset
+The SDCC project is hosted on the SDCC sourceforge site at
+\begin_inset LatexCommand \htmlurl{http://sourceforge.net/projects/sdcc}
--dumpraw option.
-\layout Itemize
+\end_inset
-This phase does the bulk of the standard optimizations and is also MCU independe
-nt.
- This phase can be broken down into several sub-phases:
-\newline
+.
+ You'll find the complete set of mailing lists
+\begin_inset LatexCommand \index{Mailing list}
-\newline
-Break down intermediate code (iCode) into basic blocks.
-\newline
-Do control flow & data flow analysis on the basic blocks.
-\newline
-Do local common subexpression elimination, then global subexpression elimination
-\newline
-Dead code elimination
-\newline
-Loop optimizations
-\newline
-If loop optimizations caused any changes then do 'global subexpression eliminati
-on' and 'dead code elimination' again.
-\layout Itemize
+\end_inset
-This phase determines the live-ranges; by live range I mean those iTemp
- variables defined by the compiler that still survive after all the optimization
-s.
- Live range analysis
-\begin_inset LatexCommand \index{Live range analysis}
+, forums, bug reporting system, patch submission
+\begin_inset LatexCommand \index{Patch submission}
\end_inset
- is essential for register allocation, since these computation determines
- which of these iTemps will be assigned to registers, and for how long.
-\layout Itemize
+ system, download
+\begin_inset LatexCommand \index{download}
-Phase five is register allocation.
- There are two parts to this process.
-\newline
+\end_inset
-\newline
-The first part I call 'register packing' (for lack of a better term).
- In this case several MCU specific expression folding is done to reduce
- register pressure.
-\newline
+ area and cvs code repository
+\begin_inset LatexCommand \index{cvs code repository}
-\newline
-The second part is more MCU independent and deals with allocating registers
- to the remaining live ranges.
- A lot of MCU specific code does creep into this phase because of the limited
- number of index registers available in the 8051.
-\layout Itemize
+\end_inset
-The Code generation phase is (unhappily), entirely MCU dependent and very
- little (if any at all) of this code can be reused for other MCU.
- However the scheme for allocating a homogenized assembler operand for each
- iCode operand may be reused.
-\layout Itemize
+ there.
+\layout Subsection
-As mentioned in the optimization section the peep-hole optimizer is rule
- based system, which can reprogrammed for other MCUs.
-\layout Section
-\pagebreak_top
-SDCDB
-\begin_inset LatexCommand \index{sdcdb}
+Reporting Bugs
+\begin_inset LatexCommand \index{Bugs}
\end_inset
- - Source Level Debugger
-\begin_inset LatexCommand \index{Debugger}
+
+\begin_inset LatexCommand \index{Reporting bugs}
\end_inset
\layout Standard
-SDCC is distributed with a source level debugger.
- 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 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
- (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.
-\layout Subsection
+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
-Compiling for Debugging
\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 Subsection
+\backslash
+/
+\end_inset
-How the Debugger Works
-\layout Standard
+-dumpall
+\begin_inset LatexCommand \index{-\/-dumpall}
-When the -
-\begin_inset ERT
-status Collapsed
+\end_inset
+
+ 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.
+
+\layout Enumerate
-\layout Standard
+Specify the exact command you use to run SDCC, or attach your Makefile.
+
+\layout Enumerate
-\backslash
-/
-\end_inset
+Specify the SDCC version (type "sdcc -v"), your platform, and operating
+ system.
+
+\layout Enumerate
--debug option is specified the compiler generates extra symbol information
- some of which are put into the 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 Subsection
+Provide an exact copy of any error message or incorrect output.
+
+\layout Enumerate
-Starting the Debugger
+Put something meaningful in the subject of your message.
\layout Standard
-The debugger can be started using the following command line.
- (Assume the file you are debugging has the file name foo).
-\newline
+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
-\newline
+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}
-\family sans
-\series bold
-sdcdb foo
-\newline
+\end_inset
-\family default
-\series default
+.
+\layout Subsection
-\newline
-The debugger will look for the following files.
-\layout Itemize
+Requesting Features
+\begin_inset LatexCommand \label{sub:Requesting-Features}
-foo.c - the source file.
-\layout Itemize
+\end_inset
-foo.cdb - the debugger symbol information file.
-\layout Itemize
-foo.ihx - the Intel hex format
-\begin_inset LatexCommand \index{Intel hex format}
+\begin_inset LatexCommand \index{Feature request}
\end_inset
- object file.
-\layout Subsection
-
-Command Line Options.
-\layout Itemize
-
--
-\begin_inset ERT
-status Collapsed
-\layout Standard
+\begin_inset LatexCommand \index{Requesting features}
-\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
-/
+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
--directory option should be -
-\begin_inset ERT
-status Collapsed
+.
+\layout Subsection
+Getting Help
\layout Standard
-\backslash
-/
+These links should take you directly to the
+\begin_inset LatexCommand \url[Mailing lists]{http://sourceforge.net/mail/?group_id=599}
+
\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
+\begin_inset Foot
+collapsed false
--fullname - used by GUI front ends.
-\layout Itemize
+\layout Standard
--cpu <cpu-type> - this argument is passed to the simulator please see the
- simulator docs for details.
-\layout Itemize
+Traffic on sdcc-devel and sdcc-user is about 100 mails/month each not counting
+ automated messages (mid 2003)
+\end_inset
--X <Clock frequency > this options is passed to the simulator please see
- the simulator docs for details.
-\layout Itemize
+ and the
+\begin_inset LatexCommand \url[Forums]{http://sourceforge.net/forum/?group_id=599}
--s <serial port file> passed to simulator see the simulator docs for details.
-\layout Itemize
+\end_inset
--S <serial in,out> passed to simulator see the simulator docs for details.
+, lists and forums are archived so if you are lucky someone already had
+ a similar problem.
\layout Subsection
-Debugger Commands.
-\layout Standard
+ChangeLog
+\begin_inset LatexCommand \index{Changelog}
-As mention earlier the command interface for the debugger has been deliberately
- 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.
-\layout Subsubsection
+\end_inset
-break [line | file:line | function | file:function]
-\layout Standard
-Set breakpoint at specified line or function:
-\newline
+\layout Standard
-\newline
+You can follow the status of the cvs version
+\begin_inset LatexCommand \index{version}
-\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
+\end_inset
-clear [line | file:line | function | file:function ]
-\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}
-Clear breakpoint at specified line or function:
-\newline
+\end_inset
-\newline
+ in the cvs-repository.
+\layout Subsection
-\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
+Release policy
+\begin_inset LatexCommand \index{Release policy}
-continue
-\layout Standard
+\end_inset
-Continue program being debugged, after breakpoint.
-\layout Subsubsection
-finish
\layout Standard
-Execute till the end of the current function.
-\layout Subsubsection
+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}
-delete [n]
-\layout Standard
+\end_inset
-Delete breakpoint number 'n'.
- If used without any option clear ALL user defined break points.
-\layout Subsubsection
+, 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}
-info [break | stack | frame | registers ]
-\layout Itemize
+\end_inset
-info break - list all breakpoints
-\layout Itemize
+.
+\layout Subsection
-info stack - show the function call stack.
-\layout Itemize
+Examples
+\begin_inset LatexCommand \index{Examples}
-info frame - show information about the current execution frame.
-\layout Itemize
+\end_inset
-info registers - show content of all registers.
-\layout Subsubsection
-step
\layout Standard
-Step program until it reaches a different source line.
-\layout Subsubsection
+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}
-next
-\layout Standard
+\end_inset
-Step program, proceeding through subroutine calls.
-\layout Subsubsection
+
+\emph default
+web site or at
+\begin_inset LatexCommand \url{http://www.pjrc.com/tech/8051/}
-run
-\layout Standard
+\end_inset
-Start debugged program.
-\layout Subsubsection
+.
+\layout Comment
-ptype variable
-\layout Standard
+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 Subsection
+
+Quality control
+\begin_inset LatexCommand \index{Quality control}
+
+\end_inset
-Print type information of the variable.
-\layout Subsubsection
-print variable
\layout Standard
-print value of variable.
-\layout Subsubsection
+The compiler is passed through nightly compile and build checks.
+ The so called
+\shape italic
+regression tests
+\shape default
-file filename
-\layout Standard
+\begin_inset LatexCommand \index{Regression test}
-load the given file name.
- Note this is an alternate method of loading file for debugging.
-\layout Subsubsection
+\end_inset
-frame
-\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}
-print information about current frame.
-\layout Subsubsection
+\end_inset
-set srcmode
+
+\shape default
+ about this.
\layout Standard
-Toggle between C source & assembly source.
-\layout Subsubsection
+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
+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}
-! simulator command
-\layout Standard
+\end_inset
-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
+ checking corner cases of SDCC or if you plan to submit patches
+\begin_inset LatexCommand \index{Patch submission}
-quit.
+\end_inset
+
+.
\layout Standard
-"Watch me now.
- Iam going Down.
- My name is Bobby Brown"
+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
+\pagebreak_top
+SDCC Technical Data
\layout Subsection
-Interfacing with XEmacs
-\begin_inset LatexCommand \index{XEmacs}
+Optimizations
+\begin_inset LatexCommand \index{Optimizations}
\end_inset
-\begin_inset LatexCommand \index{Emacs}
+\layout Standard
+
+SDCC performs a host of standard optimizations in addition to some MCU specific
+ optimizations.
+
+\layout Subsubsection
+
+Sub-expression Elimination
+\begin_inset LatexCommand \index{Subexpression elimination}
\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
+The compiler does local and global common subexpression elimination, e.g.:
+
+\layout Verse
-\newline
\family typewriter
-(load-file sdcdbsrc.el)
-\family default
-
+i = x + y + 1;
\newline
+j = x + y;
+\layout Standard
+
+will be translated to
+\layout Verse
+
+\family typewriter
+iTemp = x + y;
\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:
+i = iTemp + 1;
\newline
+j = iTemp;
+\layout Standard
-\newline
+Some subexpressions are not as obvious as the above example, e.g.:
+\layout Verse
-\family sans
-\series bold
-ESC-x sdcdbsrc
-\family default
-\series default
+\family typewriter
+a->b[i].c = 10;
\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
-You will prompted to enter the file name to be debugged.
-
+iTemp.c = 10;
\newline
+iTemp.d = 11;
+\layout Standard
-\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
+The compiler will try to keep these temporary variables in registers.
+\layout Subsubsection
-sdcdbsrc-cpu-type '51
-\layout Itemize
+Dead-Code Elimination
+\begin_inset LatexCommand \index{Dead-code elimination}
-sdcdbsrc-frequency '11059200
-\layout Itemize
+\end_inset
-sdcdbsrc-serial nil
-\layout Standard
-The following is a list of key mapping for the debugger interface.
-\layout Standard
+\layout Verse
-\SpecialChar ~
\family typewriter
+int global;
+\newline
\newline
-;; Current Listing ::
+void f () {
\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
+int i;
\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 ~
+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
+
+will be changed to
+\layout Verse
+
+
+\family typewriter
+int global;
+\newline
+
+\newline
+void f () {
\newline
-;; n\SpecialChar ~
\SpecialChar ~
\SpecialChar ~
+global = 2;
+\newline
\SpecialChar ~
\SpecialChar ~
+return;
+\newline
+}
+\layout Subsubsection
+
+Copy-Propagation
+\begin_inset LatexCommand \index{Copy propagation}
+
+\end_inset
+
+
+\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
+
+will be changed to
+\layout Verse
+
+
+\family typewriter
+int f() {
+\newline
\SpecialChar ~
- sdcdb-next-from-src\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 Subsubsection
+
+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 ~
-SDCDB next command
-\newline
-;; b\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++)
+\newline
\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 ~
- sdcdb-back-from-src\SpecialChar ~
\SpecialChar ~
+ar[itemp1] = itemp2;
+\newline
\SpecialChar ~
\SpecialChar ~
\SpecialChar ~
\SpecialChar ~
+itemp1 += 5;
+\newline
\SpecialChar ~
\SpecialChar ~
\SpecialChar ~
\SpecialChar ~
-SDCDB back command
+itemp2 += 3;
+\newline
+}
+\layout Standard
+
+The more expensive multiplication
+\begin_inset LatexCommand \index{Multiplication}
+
+\end_inset
+
+ is changed to a less expensive addition.
+\layout Subsubsection
+
+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
-;; c\SpecialChar ~
-\SpecialChar ~
\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 Subsubsection
+
+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;
+\newline
+i /= 2;\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 Subsubsection
+
+'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 ~
- sdcdb-cont-from-src\SpecialChar ~
\SpecialChar ~
\SpecialChar ~
\SpecialChar ~
\SpecialChar ~
\SpecialChar ~
\SpecialChar ~
-SDCDB continue command
-\newline
-;; s\SpecialChar ~
\SpecialChar ~
\SpecialChar ~
\SpecialChar ~
\SpecialChar ~
\SpecialChar ~
\SpecialChar ~
+switch (i) {
+\newline
\SpecialChar ~
\SpecialChar ~
- sdcdb-step-from-src\SpecialChar ~
\SpecialChar ~
+case 4: ...\SpecialChar ~
\SpecialChar ~
\SpecialChar ~
\SpecialChar ~
\SpecialChar ~
\SpecialChar ~
\SpecialChar ~
-SDCDB step command
-\newline
-;; ?\SpecialChar ~
\SpecialChar ~
\SpecialChar ~
\SpecialChar ~
\SpecialChar ~
\SpecialChar ~
\SpecialChar ~
- sdcdb-whatis-c-sexp\SpecialChar ~
\SpecialChar ~
\SpecialChar ~
\SpecialChar ~
\SpecialChar ~
+case 0: ...
+
+\newline
\SpecialChar ~
\SpecialChar ~
\SpecialChar ~
+case 5: ...\SpecialChar ~
\SpecialChar ~
\SpecialChar ~
-SDCDB ptypecommand for data at
-\newline
-;;\SpecialChar ~
\SpecialChar ~
\SpecialChar ~
\SpecialChar ~
\SpecialChar ~
\SpecialChar ~
\SpecialChar ~
+case 1: ...
+
+\newline
\SpecialChar ~
\SpecialChar ~
\SpecialChar ~
+case 3: ...\SpecialChar ~
\SpecialChar ~
\SpecialChar ~
\SpecialChar ~
\SpecialChar ~
\SpecialChar ~
\SpecialChar ~
- buffer point
-\newline
-;; x\SpecialChar ~
\SpecialChar ~
\SpecialChar ~
\SpecialChar ~
\SpecialChar ~
\SpecialChar ~
\SpecialChar ~
+case 2: ...
+
+\newline
\SpecialChar ~
\SpecialChar ~
\SpecialChar ~
+case 6: ...\SpecialChar ~
\SpecialChar ~
\SpecialChar ~
\SpecialChar ~
\SpecialChar ~
- sdcdbsrc-delete\SpecialChar ~
\SpecialChar ~
\SpecialChar ~
\SpecialChar ~
\SpecialChar ~
\SpecialChar ~
\SpecialChar ~
-SDCDB Delete all breakpoints if no arg
-\newline
-;;\SpecialChar ~
\SpecialChar ~
\SpecialChar ~
\SpecialChar ~
\SpecialChar ~
\SpecialChar ~
\SpecialChar ~
+case 3: ...
+
+\newline
+}\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
+
+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 ~
-given or delete arg (C-u arg x)
+case 1: ...
+
\newline
-;; m\SpecialChar ~
\SpecialChar ~
\SpecialChar ~
+case 2: ...
+
+\newline
\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 ~
- sdcdbsrc-frame\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
\SpecialChar ~
\SpecialChar ~
+case 2: ...
+
+\newline
\SpecialChar ~
\SpecialChar ~
+case 3: ...
+
+\newline
\SpecialChar ~
\SpecialChar ~
+case 4: ...
+
+\newline
+}
+\layout Standard
+
+and
+\layout Verse
+
+
+\family typewriter
+switch (i) {
+\newline
\SpecialChar ~
\SpecialChar ~
+case 9:\SpecialChar ~
\SpecialChar ~
+...
+
+\newline
\SpecialChar ~
\SpecialChar ~
-SDCDB Display current frame if no arg,
+case 10:\SpecialChar ~
+...
+
\newline
-;;\SpecialChar ~
\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 Subsubsection
+
+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 ~
\SpecialChar ~
+(_i + 1),#0x00
+\newline
+clr\SpecialChar ~
\SpecialChar ~
+c
+\newline
+rrc\SpecialChar ~
\SpecialChar ~
+a
+\newline
+mov\SpecialChar ~
\SpecialChar ~
+_i,a
+\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
+\emph on
+
+\emph default
+so little-endian is the more efficient byte order.
+\end_inset
+
+
+\begin_inset LatexCommand \index{little-endian}
+
+\end_inset
+
+
+\begin_inset LatexCommand \index{Endianness}
+
+\end_inset
+
+ format (i.e.
+ lowest order first).
+\layout Subsubsection
+
+Bit-rotation
+\begin_inset LatexCommand \index{Bit rotation}
+
+\end_inset
+
+
+\layout Standard
+
+A special case of the bit-shift operation is bit rotation, SDCC recognizes
+ the following expression to be a left bit-rotation:
+\layout Verse
+
+
+\family typewriter
+unsigned char i;
+\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 ~
\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 Subsubsection
+
+Highest Order Bit
+\begin_inset LatexCommand \index{Highest Order Bit}
+
+\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.:
+\layout Verse
+
+
+\family typewriter
+unsigned int gint;
+\newline
+
+\newline
+foo () {
+\newline
\SpecialChar ~
\SpecialChar ~
+unsigned char hob;
+\newline
\SpecialChar ~
\SpecialChar ~
+...
+
+\newline
\SpecialChar ~
\SpecialChar ~
+hob = (gint >> 15) & 1;
+\newline
\SpecialChar ~
\SpecialChar ~
+..
+
+\newline
+}
+\layout Standard
+
+will generate the following code:
+\layout Verse
+
+
+\family typewriter
\SpecialChar ~
\SpecialChar ~
\SpecialChar ~
\SpecialChar ~
\SpecialChar ~
\SpecialChar ~
-given or display frame arg
+ 61 ;\SpecialChar ~
+ hob.c 7
\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 ~
+000A E5*01\SpecialChar ~
\SpecialChar ~
\SpecialChar ~
\SpecialChar ~
\SpecialChar ~
\SpecialChar ~
\SpecialChar ~
+ 62\SpecialChar ~
\SpecialChar ~
\SpecialChar ~
\SpecialChar ~
\SpecialChar ~
\SpecialChar ~
\SpecialChar ~
+ mov\SpecialChar ~
\SpecialChar ~
-buffer point
+ a,(_gint + 1)
\newline
-;; !\SpecialChar ~
-\SpecialChar ~
+000C 23\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
-;; p\SpecialChar ~
-\SpecialChar ~
-\SpecialChar ~
\SpecialChar ~
\SpecialChar ~
\SpecialChar ~
\SpecialChar ~
\SpecialChar ~
\SpecialChar ~
-\SpecialChar ~
-\SpecialChar ~
-\SpecialChar ~
-\SpecialChar ~
-\SpecialChar ~
- sdcdb-print-c-sexp\SpecialChar ~
-\SpecialChar ~
+ 63\SpecialChar ~
\SpecialChar ~
\SpecialChar ~
\SpecialChar ~
\SpecialChar ~
\SpecialChar ~
\SpecialChar ~
+ rl\SpecialChar ~
\SpecialChar ~
\SpecialChar ~
-SDCDB print command for data at
+ a
\newline
-;;\SpecialChar ~
-\SpecialChar ~
+000D 54 01\SpecialChar ~
\SpecialChar ~
\SpecialChar ~
\SpecialChar ~
\SpecialChar ~
\SpecialChar ~
\SpecialChar ~
+ 64\SpecialChar ~
\SpecialChar ~
\SpecialChar ~
\SpecialChar ~
\SpecialChar ~
\SpecialChar ~
\SpecialChar ~
+ anl\SpecialChar ~
\SpecialChar ~
+ a,#0x01
+\newline
+000F F5*02\SpecialChar ~
\SpecialChar ~
\SpecialChar ~
\SpecialChar ~
\SpecialChar ~
\SpecialChar ~
\SpecialChar ~
+ 65\SpecialChar ~
\SpecialChar ~
\SpecialChar ~
\SpecialChar ~
\SpecialChar ~
\SpecialChar ~
\SpecialChar ~
+ mov\SpecialChar ~
\SpecialChar ~
- buffer point
+ _foo_hob_1_1,a
+\layout Standard
+
+Variations of this case however will
+\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).
+ 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);
+\layout Standard
+
+will still be recognized.
+\layout Subsubsection
+
+Peephole Optimizer
+\begin_inset LatexCommand \label{sub:Peephole-Optimizer}
+
+\end_inset
+
+
+\begin_inset LatexCommand \index{Peephole optimizer}
+
+\end_inset
+
+
+\layout Standard
+
+The compiler uses a rule based, pattern matching and re-writing mechanism
+ for peep-hole optimization.
+ It is inspired by
+\emph on
+copt
+\emph default
+ a peep-hole optimizer by Christopher W.
+ Fraser (cwfraser@microsoft.com).
+ A default set of rules are compiled into the compiler, additional rules
+ may be added with the
+\emph on
+-
+\begin_inset ERT
+status Collapsed
+
+\layout Standard
+
+\backslash
+/
+\end_inset
+
+-peep-file
+\begin_inset LatexCommand \index{-\/-peep-file}
+
+\end_inset
+
+ <filename>
+\emph default
+ option.
+ The rule language is best illustrated with examples.
+\layout Verse
+
+
+\family typewriter
+replace {
\newline
-;; g\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
+mov %1,a
\newline
-;; t\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 ~
-\SpecialChar ~
-Toggles Sdcdbsrc mode (turns it off)
+mov a,%1
\newline
-;;
+} by {
\newline
-;; C-c C-f\SpecialChar ~
\SpecialChar ~
\SpecialChar ~
+mov %1,a
+\newline
+}
+\layout Standard
+
+The above rule will change the following assembly
+\begin_inset LatexCommand \index{Assembler routines}
+
+\end_inset
+
+ sequence:
+\layout Verse
+
+
+\family typewriter
+mov r1,a
+\newline
+mov a,r1
+\layout Standard
+
+to
+\layout Verse
+
+
+\family typewriter
+mov r1,a
+\layout Standard
+
+Note: All occurrences of a
+\emph on
+%n
+\emph default
+ (pattern variable) must denote the same string.
+ With the above rule, the assembly sequence:
+\layout Verse
+
+
+\family typewriter
+mov r1,a
+\newline
+mov a,r2
+\layout Standard
+
+will remain unmodified.
+\newline
+
+\newline
+Other special case optimizations may be added by the user (via
+\emph on
+-
+\begin_inset ERT
+status Collapsed
+
+\layout Standard
+
+\backslash
+/
+\end_inset
+
+-peep-file option
+\emph default
+).
+ E.g.
+ some variants of the 8051 MCU allow only
+\family typewriter
+ajmp
+\family default
+ and
+\family typewriter
+acall
+\family default
+.
+ The following two rules will change all
+\family typewriter
+ljmp
+\family default
+ and
+\family typewriter
+lcall
+\family default
+ to
+\family typewriter
+ajmp
+\family default
+ and
+\family typewriter
+acall
+\layout Verse
+
+
+\family typewriter
+replace { lcall %1 } by { acall %1 }
+\newline
+replace { ljmp %1 } by { ajmp %1 }
+\layout Standard
+
+The
+\emph on
+inline-assembler code
+\emph default
+ is also passed through the peep hole optimizer, thus the peephole optimizer
+ can also be used as an assembly level macro expander.
+ The rules themselves are MCU dependent whereas the rule language infra-structur
+e is MCU independent.
+ Peephole optimization rules for other MCU can be easily programmed using
+ the rule language.
+\newline
+
+\newline
+The syntax for a rule is as follows:
+\layout Verse
+
+
+\family typewriter
+rule := replace [ restart ] '{' <assembly sequence> '
+\backslash
+n'
+\newline
\SpecialChar ~
+ \SpecialChar ~
+ \SpecialChar ~
+ \SpecialChar ~
+ \SpecialChar ~
+ \SpecialChar ~
+ \SpecialChar ~
+ \SpecialChar ~
+ \SpecialChar ~
+ \SpecialChar ~
+ \SpecialChar ~
+ \SpecialChar ~
+ \SpecialChar ~
+ \SpecialChar ~
+ '}' by '{' '
+\backslash
+n'
+\newline
\SpecialChar ~
+ \SpecialChar ~
+ \SpecialChar ~
+ \SpecialChar ~
+ \SpecialChar ~
+ \SpecialChar ~
+ \SpecialChar ~
+ \SpecialChar ~
+ \SpecialChar ~
+ \SpecialChar ~
+ \SpecialChar ~
+ \SpecialChar ~
+ \SpecialChar ~
+ \SpecialChar ~
+ \SpecialChar ~
+ \SpecialChar ~
+ <assembly sequence> '
+\backslash
+n'
+\newline
\SpecialChar ~
+ \SpecialChar ~
+ \SpecialChar ~
+ \SpecialChar ~
+ \SpecialChar ~
+ \SpecialChar ~
+ \SpecialChar ~
+ \SpecialChar ~
+ \SpecialChar ~
+ \SpecialChar ~
+ \SpecialChar ~
+ \SpecialChar ~
+ \SpecialChar ~
+ \SpecialChar ~
+ '}' [if <functionName> ] '
+\backslash
+n'
+\layout Standard
+
+<assembly sequence> := assembly instruction (each instruction including
+ labels must be on a separate line).
+\newline
+
+\newline
+The optimizer will apply to the rules one by one from the top in the sequence
+ of their appearance, it will terminate when all rules are exhausted.
+ If the 'restart' option is specified, then the optimizer will start matching
+ the rules again from the top, this option for a rule is expensive (performance)
+, it is intended to be used in situations where a transformation will trigger
+ the same rule again.
+ An example of this (not a good one, it has side effects) is the following
+ rule:
+\layout Verse
+
+
+\family typewriter
+replace restart {
+\newline
\SpecialChar ~
\SpecialChar ~
- sdcdb-finish-from-src\SpecialChar ~
+pop %1
+\newline
\SpecialChar ~
\SpecialChar ~
+push %1 } by {
+\newline
\SpecialChar ~
\SpecialChar ~
+; nop
+\newline
+}
+\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
+ be eliminated, i.e.:
+\layout Verse
+
+
+\family typewriter
+pop ar1
+\newline
+pop ar2
+\newline
+push ar2
+\newline
+push ar1
+\layout Standard
+
+would result in:
+\layout Verse
+
+
+\family typewriter
+pop ar1
+\newline
+; nop
+\newline
+push ar1
+\layout Standard
+
+
+\emph on
+with
+\emph default
+ the restart option the rule will be applied again to the resulting code
+ and then all the pop-push pairs will be eliminated to yield:
+\layout Verse
+
+
+\family typewriter
+; nop
+\newline
+; nop
+\layout Standard
+
+A conditional function can be attached to a rule.
+ Attaching rules are somewhat more involved, let me illustrate this with
+ an example.
+\layout Verse
+
+
+\family typewriter
+replace {
+\newline
\SpecialChar ~
+ \SpecialChar ~
+ \SpecialChar ~
+ljmp %5
+\newline
+%2:
+\newline
+} by {
+\newline
\SpecialChar ~
+ \SpecialChar ~
+ \SpecialChar ~
+sjmp %5
+\newline
+%2:
+\newline
+} if labelInRange
+\layout Standard
+
+The optimizer does a look-up of a function name table defined in function
+
+\emph on
+callFuncByName
+\emph default
+ in the source file SDCCpeeph.c, with the name
+\emph on
+labelInRange
+\emph default
+.
+ If it finds a corresponding entry the function is called.
+ Note there can be no parameters specified for these functions, in this
+ case the use of
+\emph on
+%5
+\emph default
+ is crucial, since the function
+\emph on
+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 Subsection
+
+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, 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 ~
-SDCDB finish command
+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 Subsection
+
+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
+
+
+\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 at the start of the external ram segment, and is 256 bytes
+ in size.
+ When -
+\begin_inset ERT
+status Collapsed
+
+\layout Standard
+
+\backslash
+/
+\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 -
+\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).
+\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 Subsection
+
+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.
+\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.:
+\begin_deeper
+\layout Verse
+
+
+\family typewriter
+struct s { ...
+ };
\newline
-;;
+struct s s1, s2;
\newline
-;; C-x SPC\SpecialChar ~
-\SpecialChar ~
-\SpecialChar ~
-\SpecialChar ~
-\SpecialChar ~
-\SpecialChar ~
-\SpecialChar ~
-\SpecialChar ~
- sdcdb-break\SpecialChar ~
-\SpecialChar ~
-\SpecialChar ~
-\SpecialChar ~
-\SpecialChar ~
-\SpecialChar ~
-\SpecialChar ~
-\SpecialChar ~
-\SpecialChar ~
-\SpecialChar ~
-\SpecialChar ~
-\SpecialChar ~
-\SpecialChar ~
-\SpecialChar ~
-\SpecialChar ~
-\SpecialChar ~
-\SpecialChar ~
-\SpecialChar ~
-Set break for line with point
+foo()
+\newline
+{
\newline
-;; ESC t\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 ~
\SpecialChar ~
-Toggle Sdcdbsrc mode
+...
+
\newline
-;; ESC m\SpecialChar ~
\SpecialChar ~
\SpecialChar ~
\SpecialChar ~
\SpecialChar ~
+s1 = s2 ; /* is invalid in SDCC although allowed in ANSI */
+\newline
\SpecialChar ~
\SpecialChar ~
\SpecialChar ~
\SpecialChar ~
+...
+
+\newline
+}
+\newline
+struct s foo1 (struct s parms) /* invalid in SDCC although allowed in ANSI
+ */
+\newline
+{
+\newline
\SpecialChar ~
- sdcdbsrc-srcmode\SpecialChar ~
\SpecialChar ~
\SpecialChar ~
\SpecialChar ~
+struct s rets;
+\newline
\SpecialChar ~
\SpecialChar ~
\SpecialChar ~
\SpecialChar ~
+...
+
+\newline
\SpecialChar ~
\SpecialChar ~
\SpecialChar ~
\SpecialChar ~
- Toggle list mode
-\newline
-;;
-\family default
-
+return rets;/* is invalid in SDCC although allowed in ANSI */
\newline
+}
+\end_deeper
+\layout Itemize
-\layout Section
-
-Other Processors
-\layout Subsection
-
-The Z80 and gbz80 port
-\layout Standard
-
-SDCC can target both the Zilog Z80 and the Nintendo Gameboy's Z80-like gbz80.
- The port is incomplete - long support is incomplete (mul, div and mod are
- unimplemented), and both float and bitfield support is missing.
- Apart from that the code generated is correct.
-\layout Standard
-
-As always, the code is the authoritave reference - see z80/ralloc.c and z80/gen.c.
- The stack 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 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 Section
-\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
- about 40,000 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
-
-The SDCC project is hosted on the sdcc sourceforge site at
-\begin_inset LatexCommand \htmlurl{http://sourceforge.net/projects/sdcc}
+'long long
+\begin_inset LatexCommand \index{long long (not supported)}
\end_inset
-.
- You'll find the complete set of mailing lists
-\begin_inset LatexCommand \index{Mailing list}
+' (64 bit integers
+\begin_inset LatexCommand \index{int (64 bit) (not supported)}
\end_inset
-, forums, bug reporting system, patch submission
-\begin_inset LatexCommand \index{Patch submission}
-
-\end_inset
+) not supported.
+\layout Itemize
- system, download
-\begin_inset LatexCommand \index{download}
+'double
+\begin_inset LatexCommand \index{double (not supported)}
\end_inset
- area and cvs code repository
-\begin_inset LatexCommand \index{cvs code repository}
+' precision floating point
+\begin_inset LatexCommand \index{Floating point support}
\end_inset
- there.
-\layout Subsection
-
-Reporting Bugs
-\begin_inset LatexCommand \index{Bugs}
-
-\end_inset
+not supported.
+\layout Itemize
+No support for setjmp and longjmp (for now).
+\layout Itemize
-\begin_inset LatexCommand \index{Reporting bugs}
+Old K&R style
+\begin_inset LatexCommand \index{K\&R style}
\end_inset
+ function declarations are NOT allowed.
+\begin_deeper
+\layout Verse
-\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
-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
+foo(i,j) /* this old style of function declarations */
+\newline
+int i,j; /* are valid in ANSI but not valid in SDCC */
+\newline
+{
+\newline
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+...
+
+\newline
+}
+\end_deeper
+\layout Itemize
-\layout Standard
+functions declared as pointers
+\begin_inset LatexCommand \index{Pointers}
-\backslash
-/
\end_inset
--dumpall
-\begin_inset LatexCommand \index{-\/-dumpall}
-
-\end_inset
- option can sometimes be useful in locating optimization problems.
- When reporting a bug please maker sure you:
-\layout Enumerate
+\begin_inset LatexCommand \index{function pointers}
-Attach the code you are compiling with SDCC.
-
-\layout Enumerate
+\end_inset
-Specify the exact command you use to run SDCC, or attach your Makefile.
-
-\layout Enumerate
+ must be dereferenced during the call.
+\begin_deeper
+\layout Verse
-Specify the SDCC version (type "sdcc -v"), your platform, and operating
- system.
-
-\layout Enumerate
-Provide an exact copy of any error message or incorrect output.
+\family typewriter
+int (*foo)();
+\newline
+...
-\layout Enumerate
-
-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
-
-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
-
-.
+\newline
+/* has to be called like this */
+\newline
+(*foo)(); /* ANSI standard allows calls to be made like 'foo()' */
+\end_deeper
\layout Subsection
-Requesting Features
-\begin_inset LatexCommand \index{Feature request}
+Cyclomatic Complexity
+\begin_inset LatexCommand \index{Cyclomatic complexity}
\end_inset
-\begin_inset LatexCommand \index{Requesting features}
+\layout Standard
-\end_inset
+Cyclomatic complexity of a function is defined as the number of independent
+ paths the program can take during execution of the function.
+ This is an important number since it defines the number test cases you
+ have to generate to validate the function.
+ The accepted industry standard for complexity number is 10, if the cyclomatic
+ complexity reported by SDCC exceeds 10 you should think about simplification
+ of the function logic.
+ Note that the complexity level is not related to the number of lines of
+ code in a function.
+ Large functions can have low complexity, and small functions can have large
+ complexity levels.
+
+\newline
+\newline
+SDCC uses the following formula to compute the complexity:
+\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
+complexity = (number of edges in control flow graph) - (number of nodes
+ in control flow graph) + 2;
+\newline
-.
+\newline
+Having said that the industry standard is 10, you should be aware that in
+ some cases it be may unavoidable to have a complexity level of less than
+ 10.
+ For example if you have switch statement with more than 10 case labels,
+ each case label adds one to the complexity level.
+ The complexity level is by no means an absolute measure of the algorithmic
+ complexity of the function, it does however provide a good starting point
+ for which functions you might look at for further optimization.
\layout Subsection
-Getting Help
-\layout Standard
+Other Processors
+\layout Subsubsection
-These links should take you directly to the
-\begin_inset LatexCommand \url[Mailing lists]{http://sourceforge.net/mail/?group_id=599}
+MCS51 variants
+\begin_inset LatexCommand \label{sub:MCS51-variants}
\end_inset
-\begin_inset Foot
-collapsed false
-
-\layout Standard
-
-Traffic on sdcc-devel and sdcc-user is about 100 mails/month each not counting
- automated messages (mid 2003)
-\end_inset
-
- and the
-\begin_inset LatexCommand \url[Forums]{http://sourceforge.net/forum/?group_id=599}
+\begin_inset LatexCommand \index{MCS51 variants}
\end_inset
-, lists and forums are archived so if you are lucky someone already had
- a similar problem.
-\layout Subsection
-
-ChangeLog
-\begin_inset LatexCommand \index{Changelog}
-\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
\layout Standard
-You can follow the status of the cvs version
-\begin_inset LatexCommand \index{version}
+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
- 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}
+ 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
- in the cvs-repository.
-\layout Subsection
+.
+\layout Subsubsection*
-Release policy
-\begin_inset LatexCommand \index{Release policy}
+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 Subsubsection
+The Z80 and gbz80 port
\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}
+SDCC can target both the Zilog
+\begin_inset LatexCommand \index{Z80}
\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}
+ and the Nintendo Gameboy's Z80-like gbz80
+\begin_inset LatexCommand \index{GameBoy Z80}
\end_inset
.
-\layout Subsection
-
-Examples
-\begin_inset LatexCommand \index{Examples}
+ 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.
\layout Standard
-You'll find some small examples in the directory sdcc/device/examples/
-\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?
+As always, the code is the authoritative reference - see z80/ralloc.c and
+ z80/gen.c.
+ The stack 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 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
-Quality control
-\begin_inset LatexCommand \index{Quality control}
+Retargetting for other MCUs.
+\layout Standard
-\end_inset
+The issues for retargetting the compiler are far too numerous to be covered
+ by this document.
+ What follows is a brief description of each of the seven phases of the
+ compiler and its MCU dependency.
+\layout Itemize
+
+Parsing the source and building the annotated parse tree.
+ This phase is largely MCU independent (except for the language extensions).
+ Syntax & semantic checks are also done in this phase, along with some initial
+ optimizations like back patching labels and the pattern matching optimizations
+ like bit-rotation etc.
+\layout Itemize
+The second phase involves generating an intermediate code which can be easy
+ manipulated during the later phases.
+ This phase is entirely MCU independent.
+ The intermediate code generation assumes the target machine has unlimited
+ number of registers, and designates them with the name iTemp.
+ The compiler can be made to dump a human readable form of the code generated
+ by using the -
+\begin_inset ERT
+status Collapsed
\layout Standard
-The compiler is passed through nightly compile and build checks.
- The so called
-\shape italic
-regression tests
-\shape default
+\backslash
+/
+\end_inset
-\begin_inset LatexCommand \index{Regression test}
+-dumpraw option.
+\layout Itemize
-\end_inset
+This phase does the bulk of the standard optimizations and is also MCU independe
+nt.
+ This phase can be broken down into several sub-phases:
+\newline
- 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
+\newline
+Break down intermediate code (iCode) into basic blocks.
+\newline
+Do control flow & data flow analysis on the basic blocks.
+\newline
+Do local common subexpression elimination, then global subexpression elimination
+\newline
+Dead code elimination
+\newline
+Loop optimizations
+\newline
+If loop optimizations caused any changes then do 'global subexpression eliminati
+on' and 'dead code elimination' again.
+\layout Itemize
+
+This phase determines the live-ranges; by live range I mean those iTemp
+ variables defined by the compiler that still survive after all the optimization
s.
- There is a separate document
-\shape italic
-test_suite.pdf
-\begin_inset LatexCommand \index{Test suite}
+ Live range analysis
+\begin_inset LatexCommand \index{Live range analysis}
\end_inset
+ is essential for register allocation, since these computation determines
+ which of these iTemps will be assigned to registers, and for how long.
+\layout Itemize
-\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
-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}
-
-\end_inset
+Phase five is register allocation.
+ There are two parts to this process.
+\newline
- checking corner cases of SDCC or if you plan to submit patches
-\begin_inset LatexCommand \index{Patch submission}
+\newline
+The first part I call 'register packing' (for lack of a better term).
+ In this case several MCU specific expression folding is done to reduce
+ register pressure.
+\newline
-\end_inset
+\newline
+The second part is more MCU independent and deals with allocating registers
+ to the remaining live ranges.
+ A lot of MCU specific code does creep into this phase because of the limited
+ number of index registers available in the 8051.
+\layout Itemize
-.
-\layout Standard
+The Code generation phase is (unhappily), entirely MCU dependent and very
+ little (if any at all) of this code can be reused for other MCU.
+ However the scheme for allocating a homogenized assembler operand for each
+ iCode operand may be reused.
+\layout Itemize
-The pic port uses a different set of regression tests, you'll find them
- in the directory
-\shape italic
-sdcc/src/regression
-\shape default
-.
+As mentioned in the optimization section the peep-hole optimizer is rule
+ based system, which can reprogrammed for other MCUs.
\layout Section
\pagebreak_top
Compiler internals
\layout Subsection
The anatomy of the compiler
+\begin_inset LatexCommand \label{sub:The-anatomy-of}
+
+\end_inset
+
+
\layout Standard
if (something)
\layout Standard
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
[basic block 2]
\layout Standard
else
\layout Standard
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
+\SpecialChar ~
[basic block 3]
\layout Standard
Alphabetical index
\layout Standard
-To avoid confusion, the installation and building options for sdcc itself
+To avoid confusion, the installation and building options for SDCC itself
(chapter 2) are not part of the index.
\layout Standard
projects / fw / sdcc / blobdiff