1 #LyX 1.3 created this file. For more info see http://www.lyx.org/
5 \pdfoptionpdfminorversion=3
7 pdftitle={SDCC Compiler User Guide},
8 pdfauthor={SDCC development team},
9 pdfsubject={installation, user manual},
10 pdfkeywords={8032 8051 ansi c compiler CPU DS390
11 embedded GPL HC08 manual mcs51 microcontroller PIC Z80},
13 linkcolor=blue] {hyperref}
17 \emergencystretch=30pt
22 \inputencoding default
25 \paperfontsize default
27 \papersize letterpaper
32 \use_numerical_citations 0
33 \paperorientation portrait
40 \paragraph_separation indent
42 \quotes_language swedish
50 Please note: double dashed longoptions (e.g.
51 --version) are written this way: -
65 three consecutive dashes simply result in a long resp.
69 Architecture specific stuff (like memory models, code examples) should maybe
73 into seperate sections/chapters/appendices (it is hard to document PIC or
77 a 8051 centered document) - for now simply add.
80 SDCC Compiler User Guide
94 The above strings enclosed in $ are automatically updated by cvs
98 \begin_inset LatexCommand \tableofcontents{}
131 ompiler) is an open source, retargettable, optimizing ANSI-C compiler by
136 designed for 8 bit Microprocessors.
137 The current version targets Intel MCS51 based Microprocessors (8031, 8032,
139 \begin_inset LatexCommand \index{8031, 8032, 8051, 8052, mcs51 CPU}
143 , etc.), Dallas DS80C390 variants, Freescale (formerly Motorola) HC08 and
144 Zilog Z80 based MCUs.
145 It can be retargetted for other microprocessors, support for Microchip
146 PIC, Atmel AVR is under development.
147 The entire source code for the compiler is distributed under GPL.
149 \begin_inset LatexCommand \index{asXXXX (as-gbz80, as-hc08, asx8051, as-z80)}
154 \begin_inset LatexCommand \index{aslink}
158 , an open source retargettable assembler & linker.
159 SDCC has extensive language extensions suitable for utilizing various microcont
160 rollers and underlying hardware effectively.
165 In addition to the MCU specific optimizations SDCC also does a host of standard
169 global sub expression elimination,
172 loop optimizations (loop invariant, strength reduction of induction variables
176 constant folding & propagation,
182 dead code elimination
192 For the back-end SDCC uses a global register allocation scheme which should
193 be well suited for other 8 bit MCUs.
198 The peep hole optimizer uses a rule based substitution mechanism which is
204 Supported data-types are:
207 char (8 bits, 1 byte),
210 short and int (16 bits, 2 bytes),
213 long (32 bit, 4 bytes)
220 The compiler also allows
222 inline assembler code
224 to be embedded anywhere in a function.
225 In addition, routines developed in assembly can also be called.
229 SDCC also provides an option (-
239 -cyclomatic) to report the relative complexity of a function.
240 These functions can then be further optimized, or hand coded in assembly
246 SDCC also comes with a companion source level debugger SDCDB, the debugger
247 currently uses ucSim a freeware simulator for 8051 and other micro-controllers.
252 The latest version can be downloaded from
253 \begin_inset LatexCommand \url{http://sdcc.sourceforge.net/snap.php}
263 Please note: the compiler will probably always be some steps ahead of this
268 \begin_inset LatexCommand \index{Status of documentation}
278 Obviously this has pros and cons
287 All packages used in this compiler system are
295 ; source code for all the sub-packages (pre-processor, assemblers, linkers
296 etc) is distributed with the package.
297 This documentation is maintained using a freeware word processor (LyX).
299 This program is free software; you can redistribute it and/or modify it
300 under the terms of the GNU General Public License
301 \begin_inset LatexCommand \index{GNU General Public License, GPL}
305 as published by the Free Software Foundation; either version 2, or (at
306 your option) any later version.
307 This program is distributed in the hope that it will be useful, but WITHOUT
308 ANY WARRANTY; without even the implied warranty
309 \begin_inset LatexCommand \index{warranty}
313 of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
314 See the GNU General Public License for more details.
315 You should have received a copy of the GNU General Public License along
316 with this program; if not, write to the Free Software Foundation, 59 Temple
317 Place - Suite 330, Boston, MA 02111-1307, USA.
318 In other words, you are welcome to use, share and improve this program.
319 You are forbidden to forbid anyone else to use, share and improve what
321 Help stamp out software-hoarding!
324 Typographic conventions
325 \begin_inset LatexCommand \index{Typographic conventions}
332 Throughout this manual, we will use the following convention.
333 Commands you have to type in are printed in
341 Code samples are printed in
346 Interesting items and new terms are printed in
351 Compatibility with previous versions
352 \begin_inset LatexCommand \index{Compatibility with previous versions}
359 This version has numerous bug fixes compared with the previous version.
360 But we also introduced some incompatibilities with older versions.
361 Not just for the fun of it, but to make the compiler more stable, efficient
363 \begin_inset LatexCommand \index{ANSI-compliance}
368 \begin_inset LatexCommand \ref{sub:ANSI-Compliance}
372 for ANSI-Compliance).
378 short is now equivalent to int (16 bits), it used to be equivalent to char
379 (8 bits) which is not ANSI compliant.
382 the default directory for gcc-builds where include, library and documentation
383 files are stored is now in /usr/local/share.
386 char type parameters to vararg functions are casted to int unless explicitly
403 will push a as an int and as a char resp.
416 -regextend has been removed.
429 -noregparms has been removed.
442 -stack-after-data has been removed.
446 \begin_inset LatexCommand \index{bit}
451 \begin_inset LatexCommand \index{sbit}
456 \begin_inset LatexCommand \index{\_\_sbit}
460 types now consistently behave like the C99 _Bool type with respect to type
462 \begin_inset LatexCommand \index{type conversion}
467 \begin_inset LatexCommand \index{type promotion}
472 The most common incompatibility resulting from this change is related to
474 \begin_inset LatexCommand \index{Bit toggling}
488 b = ~b; /* equivalent to b=1 instead of toggling b */
492 b = !b; /* toggles b */
496 In previous versions, both forms would have toggled the bit.
501 <pending: more incompatibilities?>
507 What do you need before you start installation of SDCC? A computer, and
509 The preferred method of installation is to compile SDCC from source using
511 For Windows some pre-compiled binary distributions are available for your
513 You should have some experience with command line tools and compiler use.
519 The SDCC home page at
520 \begin_inset LatexCommand \url{http://sdcc.sourceforge.net/}
524 is a great place to find distribution sets.
525 You can also find links to the user mailing lists that offer help or discuss
526 SDCC with other SDCC users.
527 Web links to other SDCC related sites can also be found here.
528 This document can be found in the DOC directory of the source package as
530 A pdf version of this document is available at
531 \begin_inset LatexCommand \url{http://sdcc.sourceforge.net/doc/sdccman.pdf}
536 Some of the other tools (simulator and assembler) included with SDCC contain
537 their own documentation and can be found in the source distribution.
538 If you want the latest unreleased software, the complete source package
539 is available directly by anonymous CVS on cvs.sdcc.sourceforge.net.
542 Wishes for the future
545 There are (and always will be) some things that could be done.
546 Here are some I can think of:
553 char KernelFunction3(char p) at 0x340;
561 \begin_inset LatexCommand \index{code banking (limited support)}
571 If you can think of some more, please see the section
572 \begin_inset LatexCommand \ref{sub:Requesting-Features}
576 about filing feature requests
577 \begin_inset LatexCommand \index{Requesting features}
582 \begin_inset LatexCommand \index{Feature request}
592 \begin_inset LatexCommand \index{Installation}
599 For most users it is sufficient to skip to either section
600 \begin_inset LatexCommand \ref{sub:Building-SDCC-on-Linux}
605 \begin_inset LatexCommand \ref{sub:Windows-Install}
610 More detailled instructions follow below.
614 \begin_inset LatexCommand \index{Options SDCC configuration}
621 The install paths, search paths and other options are defined when running
623 The defaults can be overridden by:
625 \labelwidthstring 00.00.0000
637 -prefix see table below
639 \labelwidthstring 00.00.0000
651 -exec_prefix see table below
653 \labelwidthstring 00.00.0000
665 -bindir see table below
667 \labelwidthstring 00.00.0000
679 -datadir see table below
681 \labelwidthstring 00.00.0000
683 docdir environment variable, see table below
685 \labelwidthstring 00.00.0000
687 include_dir_suffix environment variable, see table below
689 \labelwidthstring 00.00.0000
691 lib_dir_suffix environment variable, see table below
693 \labelwidthstring 00.00.0000
695 sdccconf_h_dir_separator environment variable, either / or
700 This character will only be used in sdccconf.h; don't forget it's a C-header,
701 therefore a double-backslash is needed there.
703 \labelwidthstring 00.00.0000
715 -disable-mcs51-port Excludes the Intel mcs51 port
717 \labelwidthstring 00.00.0000
729 -disable-gbz80-port Excludes the Gameboy gbz80 port
731 \labelwidthstring 00.00.0000
743 -disable-z80-port Excludes the z80 port
745 \labelwidthstring 00.00.0000
757 -disable-avr-port Excludes the AVR port
759 \labelwidthstring 00.00.0000
771 -disable-ds390-port Excludes the DS390 port
773 \labelwidthstring 00.00.0000
785 -disable-hc08-port Excludes the HC08 port
787 \labelwidthstring 00.00.0000
799 -disable-pic-port Excludes the PIC port
801 \labelwidthstring 00.00.0000
813 -disable-xa51-port Excludes the XA51 port
815 \labelwidthstring 00.00.0000
827 -disable-ucsim Disables configuring and building of ucsim
829 \labelwidthstring 00.00.0000
841 -disable-device-lib-build Disables automatically building device libraries
843 \labelwidthstring 00.00.0000
855 -disable-packihx Disables building packihx
857 \labelwidthstring 00.00.0000
869 -enable-libgc Use the Bohem memory allocator.
870 Lower runtime footprint.
873 Furthermore the environment variables CC, CFLAGS, ...
874 the tools and their arguments can be influenced.
875 Please see `configure -
885 -help` and the man/info pages of `configure` for details.
889 The names of the standard libraries STD_LIB, STD_INT_LIB, STD_LONG_LIB,
890 STD_FP_LIB, STD_DS390_LIB, STD_XA51_LIB and the environment variables SDCC_DIR_
891 NAME, SDCC_INCLUDE_NAME, SDCC_LIB_NAME are defined by `configure` too.
892 At the moment it's not possible to change the default settings (it was
893 simply never required).
897 These configure options are compiled into the binaries, and can only be
898 changed by rerunning 'configure' and recompiling SDCC.
899 The configure options are written in
903 to distinguish them from run time environment variables (see section search
909 \begin_inset Quotes sld
913 \begin_inset Quotes srd
916 are used by the SDCC team to build the official Win32 binaries.
917 The SDCC team uses Mingw32 to build the official Windows binaries, because
924 a gcc compiler and last but not least
927 the binaries can be built by cross compiling on Sourceforge's compile farm.
930 See the examples, how to pass the Win32 settings to 'configure'.
931 The other Win32 builds using Borland, VC or whatever don't use 'configure',
932 but a header file sdcc_vc_in.h is the same as sdccconf.h built by 'configure'
944 <lyxtabular version="3" rows="8" columns="3">
946 <column alignment="block" valignment="top" leftline="true" width="0in">
947 <column alignment="block" valignment="top" leftline="true" width="0in">
948 <column alignment="block" valignment="top" leftline="true" rightline="true" width="0in">
949 <row topline="true" bottomline="true">
950 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
958 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
966 <cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
976 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
986 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
994 <cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
1005 <row topline="true">
1006 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
1016 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
1026 <cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
1037 <row topline="true">
1038 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
1048 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
1060 <cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
1075 <row topline="true">
1076 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
1086 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
1098 <cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
1109 <row topline="true">
1110 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
1120 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
1132 <cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
1147 <row topline="true">
1148 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
1158 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
1166 <cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
1175 <row topline="true" bottomline="true">
1176 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
1186 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
1194 <cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
1212 'configure' also computes relative paths.
1213 This is needed for full relocatability of a binary package and to complete
1214 search paths (see section search paths below):
1220 \begin_inset Tabular
1221 <lyxtabular version="3" rows="4" columns="3">
1223 <column alignment="block" valignment="top" leftline="true" width="0in">
1224 <column alignment="block" valignment="top" leftline="true" width="0in">
1225 <column alignment="block" valignment="top" leftline="true" rightline="true" width="0in">
1226 <row topline="true" bottomline="true">
1227 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
1235 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
1243 <cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
1252 <row topline="true" bottomline="true">
1253 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
1263 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
1271 <cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
1280 <row bottomline="true">
1281 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
1291 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
1299 <cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
1308 <row bottomline="true">
1309 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
1319 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
1327 <cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
1360 \begin_inset Quotes srd
1364 \begin_inset Quotes srd
1378 \begin_inset Quotes srd
1382 \begin_inset Quotes srd
1410 To cross compile on linux for Mingw32 (see also 'sdcc/support/scripts/sdcc_mingw
1419 \begin_inset Quotes srd
1422 i586-mingw32msvc-gcc
1423 \begin_inset Quotes srd
1427 \begin_inset Quotes srd
1430 i586-mingw32msvc-g++
1431 \begin_inset Quotes srd
1439 \begin_inset Quotes srd
1442 i586-mingw32msvc-ranlib
1443 \begin_inset Quotes srd
1451 \begin_inset Quotes srd
1454 i586-mingw32msvc-strip
1455 \begin_inset Quotes srd
1473 \begin_inset Quotes srd
1477 \begin_inset Quotes srd
1495 \begin_inset Quotes srd
1499 \begin_inset Quotes srd
1507 \begin_inset Quotes srd
1511 \begin_inset Quotes srd
1519 \begin_inset Quotes srd
1523 \begin_inset Quotes srd
1531 \begin_inset Quotes srd
1535 \begin_inset Quotes srd
1542 sdccconf_h_dir_separator=
1543 \begin_inset Quotes srd
1555 \begin_inset Quotes srd
1572 -disable-device-lib-build
1600 -host=i586-mingw32msvc -
1610 -build=unknown-unknown-linux-gnu
1614 \begin_inset Quotes sld
1618 \begin_inset Quotes srd
1621 compile on Cygwin for Mingw32 (see also sdcc/support/scripts/sdcc_cygwin_mingw32
1630 \begin_inset Quotes srd
1634 \begin_inset Quotes srd
1642 \begin_inset Quotes srd
1646 \begin_inset Quotes srd
1664 \begin_inset Quotes srd
1668 \begin_inset Quotes srd
1686 \begin_inset Quotes srd
1690 \begin_inset Quotes srd
1698 \begin_inset Quotes srd
1702 \begin_inset Quotes srd
1710 \begin_inset Quotes srd
1714 \begin_inset Quotes srd
1722 \begin_inset Quotes srd
1726 \begin_inset Quotes srd
1733 sdccconf_h_dir_separator=
1734 \begin_inset Quotes srd
1746 \begin_inset Quotes srd
1766 'configure' is quite slow on Cygwin (at least on windows before Win2000/XP).
1777 -C' turns on caching, which gives a little bit extra speed.
1778 However if options are changed, it can be necessary to delete the config.cache
1783 \begin_inset LatexCommand \label{sub:Install-paths}
1788 \begin_inset LatexCommand \index{Install paths}
1794 \added_space_top medskip \align center
1796 \begin_inset Tabular
1797 <lyxtabular version="3" rows="5" columns="4">
1799 <column alignment="center" valignment="top" leftline="true" width="0">
1800 <column alignment="center" valignment="top" leftline="true" width="0">
1801 <column alignment="center" valignment="top" leftline="true" width="0">
1802 <column alignment="center" valignment="top" leftline="true" rightline="true" width="0">
1803 <row topline="true" bottomline="true">
1804 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
1814 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
1824 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
1834 <cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
1845 <row topline="true">
1846 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
1854 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
1864 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
1872 <cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
1885 <row topline="true">
1886 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
1894 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
1901 $DATADIR/ $INCLUDE_DIR_SUFFIX
1904 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
1909 /usr/local/share/sdcc/include
1912 <cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
1925 <row topline="true">
1926 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
1934 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
1941 $DATADIR/$LIB_DIR_SUFFIX
1944 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
1949 /usr/local/share/sdcc/lib
1952 <cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
1965 <row topline="true" bottomline="true">
1966 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
1974 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
1984 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
1989 /usr/local/share/sdcc/doc
1992 <cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
2014 *compiler, preprocessor, assembler, and linker
2020 is auto-appended by the compiler, e.g.
2021 small, large, z80, ds390 etc
2024 The install paths can still be changed during `make install` with e.g.:
2027 make install prefix=$(HOME)/local/sdcc
2030 Of course this doesn't change the search paths compiled into the binaries.
2034 Moreover the install path can be changed by defining DESTDIR
2035 \begin_inset LatexCommand \index{DESTDIR}
2042 make install DESTDIR=$(HOME)/sdcc.rpm/
2045 Please note that DESTDIR must have a trailing slash!
2049 \begin_inset LatexCommand \label{sub:Search-Paths}
2054 \begin_inset LatexCommand \index{Search path}
2061 Some search paths or parts of them are determined by configure variables
2066 , see section above).
2067 Further search paths are determined by environment variables during runtime.
2070 The paths searched when running the compiler are as follows (the first catch
2076 Binary files (preprocessor, assembler and linker)
2082 \begin_inset Tabular
2083 <lyxtabular version="3" rows="4" columns="3">
2085 <column alignment="block" valignment="top" leftline="true" width="0in">
2086 <column alignment="block" valignment="top" leftline="true" width="0in">
2087 <column alignment="block" valignment="top" leftline="true" rightline="true" width="0in">
2088 <row topline="true" bottomline="true">
2089 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
2097 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
2105 <cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
2114 <row topline="true">
2115 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
2125 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
2133 <cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
2144 <row topline="true">
2145 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
2150 Path of argv[0] (if available)
2153 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
2161 <cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
2170 <row topline="true" bottomline="true">
2171 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
2179 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
2187 <cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
2212 \begin_inset Tabular
2213 <lyxtabular version="3" rows="6" columns="3">
2215 <column alignment="block" valignment="top" leftline="true" width="1.5in">
2216 <column alignment="block" valignment="top" leftline="true" width="1.5in">
2217 <column alignment="block" valignment="top" leftline="true" rightline="true" width="0in">
2218 <row topline="true" bottomline="true">
2219 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
2227 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
2235 <cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
2244 <row topline="true">
2245 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
2263 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
2281 <cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
2300 <row topline="true">
2301 <cell alignment="left" valignment="top" topline="true" leftline="true" usebox="none">
2309 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
2317 <cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
2326 <row topline="true">
2327 <cell alignment="left" valignment="top" topline="true" leftline="true" usebox="none">
2341 <cell alignment="left" valignment="top" topline="true" leftline="true" usebox="none">
2353 <cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
2364 <row topline="true">
2365 <cell alignment="left" valignment="top" topline="true" leftline="true" usebox="none">
2383 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
2433 <cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
2446 <row topline="true" bottomline="true">
2447 <cell alignment="left" valignment="top" topline="true" leftline="true" usebox="none">
2463 <cell alignment="left" valignment="top" topline="true" leftline="true" usebox="none">
2468 /usr/local/share/sdcc/
2473 <cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
2501 -nostdinc disables the last two search paths.
2511 With the exception of
2512 \begin_inset Quotes sld
2526 \begin_inset Quotes srd
2533 is auto-appended by the compiler (e.g.
2534 small, large, z80, ds390 etc.).
2541 \begin_inset Tabular
2542 <lyxtabular version="3" rows="6" columns="3">
2544 <column alignment="block" valignment="top" leftline="true" width="1.7in">
2545 <column alignment="block" valignment="top" leftline="true" width="1.2in">
2546 <column alignment="block" valignment="top" leftline="true" rightline="true" width="1.2in">
2547 <row topline="true" bottomline="true">
2548 <cell alignment="left" valignment="top" topline="true" leftline="true" usebox="none">
2556 <cell alignment="left" valignment="top" topline="true" leftline="true" usebox="none">
2564 <cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
2573 <row topline="true">
2574 <cell alignment="left" valignment="top" topline="true" leftline="true" usebox="none">
2592 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
2610 <cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
2629 <row topline="true">
2630 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
2642 <cell alignment="left" valignment="top" topline="true" leftline="true" usebox="none">
2654 <cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
2669 <row topline="true">
2670 <cell alignment="left" valignment="top" topline="true" leftline="true" usebox="none">
2681 $LIB_DIR_SUFFIX/<model>
2684 <cell alignment="left" valignment="top" topline="true" leftline="true" usebox="none">
2698 <cell alignment="left" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
2715 <row topline="true">
2716 <cell alignment="left" valignment="top" topline="true" leftline="true" usebox="none">
2731 $LIB_DIR_SUFFIX/<model>
2734 <cell alignment="left" valignment="top" topline="true" leftline="true" usebox="none">
2787 <cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
2843 <row topline="true" bottomline="true">
2844 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
2853 $LIB_DIR_SUFFIX/<model>
2856 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
2861 /usr/local/share/sdcc/
2868 <cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
2886 Don't delete any of the stray spaces in the table above without checking
2887 the HTML output (last line)!
2903 -nostdlib disables the last two search paths.
2907 \begin_inset LatexCommand \index{Building SDCC}
2914 Building SDCC on Linux
2915 \begin_inset LatexCommand \label{sub:Building-SDCC-on-Linux}
2924 Download the source package
2926 either from the SDCC CVS repository or from the nightly snapshots
2928 , it will be named something like sdcc
2939 \begin_inset LatexCommand \url{http://sdcc.sourceforge.net/snap.php}
2948 Bring up a command line terminal, such as xterm.
2953 Unpack the file using a command like:
2956 "tar -xvzf sdcc.src.tar.gz
2961 , this will create a sub-directory called sdcc with all of the sources.
2964 Change directory into the main SDCC directory, for example type:
2981 This configures the package for compilation on your system.
2997 All of the source packages will compile, this can take a while.
3013 This copies the binary executables, the include files, the libraries and
3014 the documentation to the install directories.
3015 Proceed with section
3016 \begin_inset LatexCommand \ref{sec:Testing-the-SDCC}
3023 Building SDCC on OSX 2.x
3026 Follow the instruction for Linux.
3030 On OSX 2.x it was reported, that the default gcc (version 3.1 20020420 (prerelease
3031 )) fails to compile SDCC.
3032 Fortunately there's also gcc 2.9.x installed, which works fine.
3033 This compiler can be selected by running 'configure' with:
3036 ./configure CC=gcc2 CXX=g++2
3039 Cross compiling SDCC on Linux for Windows
3042 With the Mingw32 gcc cross compiler it's easy to compile SDCC for Win32.
3043 See section 'Configure Options'.
3046 Building SDCC on Windows
3049 With the exception of Cygwin the SDCC binaries uCsim and sdcdb can't be
3051 They use Unix-sockets, which are not available on Win32.
3054 Building SDCC using Cygwin and Mingw32
3057 For building and installing a Cygwin executable follow the instructions
3063 \begin_inset Quotes sld
3067 \begin_inset Quotes srd
3070 Win32-binary can be built, which will not need the Cygwin-DLL.
3071 For the necessary 'configure' options see section 'configure options' or
3072 the script 'sdcc/support/scripts/sdcc_cygwin_mingw32'.
3076 In order to install Cygwin on Windows download setup.exe from
3077 \begin_inset LatexCommand \url[www.cygwin.com]{http://www.cygwin.com/}
3083 \begin_inset Quotes sld
3086 default text file type
3087 \begin_inset Quotes srd
3091 \begin_inset Quotes sld
3095 \begin_inset Quotes srd
3098 and download/install at least the following packages.
3099 Some packages are selected by default, others will be automatically selected
3100 because of dependencies with the manually selected packages.
3101 Never deselect these packages!
3110 gcc ; version 3.x is fine, no need to use the old 2.9x
3113 binutils ; selected with gcc
3119 rxvt ; a nice console, which makes life much easier under windoze (see below)
3122 man ; not really needed for building SDCC, but you'll miss it sooner or
3126 less ; not really needed for building SDCC, but you'll miss it sooner or
3130 cvs ; only if you use CVS access
3133 If you want to develop something you'll need:
3136 python ; for the regression tests
3139 gdb ; the gnu debugger, together with the nice GUI
3140 \begin_inset Quotes sld
3144 \begin_inset Quotes srd
3150 openssh ; to access the CF or commit changes
3153 autoconf and autoconf-devel ; if you want to fight with 'configure', don't
3154 use autoconf-stable!
3157 rxvt is a nice console with history.
3158 Replace in your cygwin.bat the line
3177 rxvt -sl 1000 -fn "Lucida Console-12" -sr -cr red
3180 -bg black -fg white -geometry 100x65 -e bash -
3193 Text selected with the mouse is automatically copied to the clipboard, pasting
3194 works with shift-insert.
3198 The other good tip is to make sure you have no //c/-style paths anywhere,
3199 use /cygdrive/c/ instead.
3200 Using // invokes a network lookup which is very slow.
3202 \begin_inset Quotes sld
3206 \begin_inset Quotes srd
3209 is too long, you can change it with e.g.
3215 SDCC sources use the unix line ending LF.
3216 Life is much easier, if you store the source tree on a drive which is mounted
3218 And use an editor which can handle LF-only line endings.
3219 Make sure not to commit files with windows line endings.
3220 The tabulator spacing
3221 \begin_inset LatexCommand \index{tabulator spacing (8 columns)}
3225 used in the project is 8.
3226 Although a tabulator spacing of 8 is a sensible choice for programmers
3227 (it's a power of 2 and allows to display 8/16 bit signed variables without
3228 loosing columns) the plan is to move towards using only spaces in the source.
3231 Building SDCC Using Microsoft Visual C++ 6.0/NET (MSVC)
3236 Download the source package
3238 either from the SDCC CVS repository or from the
3239 \begin_inset LatexCommand \url[nightly snapshots]{http://sdcc.sourceforge.net/snap.php}
3245 , it will be named something like sdcc
3252 SDCC is distributed with all the projects, workspaces, and files you need
3253 to build it using Visual C++ 6.0/NET (except for sdcdb.exe which currently
3254 doesn't build under MSVC).
3255 The workspace name is 'sdcc.dsw'.
3256 Please note that as it is now, all the executables are created in a folder
3260 Once built you need to copy the executables from sdcc
3264 bin before running SDCC.
3269 WARNING: Visual studio is very picky with line terminations; it expects
3270 the 0x0d, 0x0a DOS style line endings, not the 0x0a Unix style line endings.
3271 When using the CVS repository it's easiest to configure the cvs client
3272 to convert automatically for you.
3273 If however you are getting a message such as "This makefile was not generated
3274 by Developer Studio etc.
3276 \begin_inset Quotes srd
3279 when opening the sdcc.dsw workspace or any of the *.dsp projects, then you
3280 need to convert the Unix style line endings to DOS style line endings.
3281 To do so you can use the
3282 \begin_inset Quotes sld
3286 \begin_inset Quotes srd
3289 utility freely available on the internet.
3290 Doug Hawkins reported in the sdcc-user list that this works:
3298 SDCC> unix2dos sdcc.dsw
3304 SDCC> for /R %I in (*.dsp) do @unix2dos "%I"
3308 In order to build SDCC with MSVC you need win32 executables of bison.exe,
3309 flex.exe, and gawk.exe.
3310 One good place to get them is
3311 \begin_inset LatexCommand \url[here]{http://unxutils.sourceforge.net}
3319 Download the file UnxUtils
3320 \begin_inset LatexCommand \index{UnxUtils}
3325 Now you have to install the utilities and setup MSVC so it can locate the
3327 Here there are two alternatives (choose one!):
3334 a) Extract UnxUtils.zip to your C:
3336 hard disk PRESERVING the original paths, otherwise bison won't work.
3337 (If you are using WinZip make certain that 'Use folder names' is selected)
3341 b) In the Visual C++ IDE click Tools, Options, select the Directory tab,
3342 in 'Show directories for:' select 'Executable files', and in the directories
3343 window add a new path: 'C:
3353 (As a side effect, you get a bunch of Unix utilities that could be useful,
3354 such as diff and patch.)
3361 This one avoids extracting a bunch of files you may not use, but requires
3366 a) Create a directory were to put the tools needed, or use a directory already
3374 b) Extract 'bison.exe', 'bison.hairy', 'bison.simple', 'flex.exe', and gawk.exe
3375 to such directory WITHOUT preserving the original paths.
3376 (If you are using WinZip make certain that 'Use folder names' is not selected)
3380 c) Rename bison.exe to '_bison.exe'.
3384 d) Create a batch file 'bison.bat' in 'C:
3388 ' and add these lines:
3408 _bison %1 %2 %3 %4 %5 %6 %7 %8 %9
3412 Steps 'c' and 'd' are needed because bison requires by default that the
3413 files 'bison.simple' and 'bison.hairy' reside in some weird Unix directory,
3414 '/usr/local/share/' I think.
3415 So it is necessary to tell bison where those files are located if they
3416 are not in such directory.
3417 That is the function of the environment variables BISON_SIMPLE and BISON_HAIRY.
3421 e) In the Visual C++ IDE click Tools, Options, select the Directory tab,
3422 in 'Show directories for:' select 'Executable files', and in the directories
3423 window add a new path: 'c:
3426 Note that you can use any other path instead of 'c:
3428 util', even the path where the Visual C++ tools are, probably: 'C:
3432 Microsoft Visual Studio
3437 So you don't have to execute step 'e' :)
3441 Open 'sdcc.dsw' in Visual Studio, click 'build all', when it finishes copy
3442 the executables from sdcc
3446 bin, and you can compile using SDCC.
3449 Building SDCC Using Borland
3452 From the sdcc directory, run the command "make -f Makefile.bcc".
3453 This should regenerate all the .exe files in the bin directory except for
3454 sdcdb.exe (which currently doesn't build under Borland C++).
3457 If you modify any source files and need to rebuild, be aware that the dependenci
3458 es may not be correctly calculated.
3459 The safest option is to delete all .obj files and run the build again.
3460 From a Cygwin BASH prompt, this can easily be done with the command (be
3461 sure you are in the sdcc directory):
3471 ( -name '*.obj' -o -name '*.lib' -o -name '*.rul'
3473 ) -print -exec rm {}
3482 or on Windows NT/2000/XP from the command prompt with the command:
3489 del /s *.obj *.lib *.rul
3492 from the sdcc directory.
3495 Windows Install Using a ZIP Package
3498 Download the binary zip package from
3499 \begin_inset LatexCommand \url{http://sdcc.sf.net/snap.php}
3503 and unpack it using your favorite unpacking tool (gunzip, WinZip, etc).
3504 This should unpack to a group of sub-directories.
3505 An example directory structure after unpacking the mingw32 package is:
3510 bin for the executables, c:
3518 lib for the include and libraries.
3521 Adjust your environment variable PATH to include the location of the bin
3522 directory or start sdcc using the full path.
3525 Windows Install Using the Setup Program
3526 \begin_inset LatexCommand \label{sub:Windows-Install}
3533 Download the setup program
3535 sdcc-x.y.z-setup.exe
3537 for an official release from
3540 \begin_inset LatexCommand \url{http://sf.net/project/showfiles.php?group_id=599}
3544 or a setup program for one of the snapshots
3546 sdcc_yyyymmdd_setup.exe
3549 \begin_inset LatexCommand \url{http://sdcc.sf.net/snap.php}
3554 A windows typical installer will guide you through the installation process.
3557 Building the Documentation
3560 If the necessary tools (LyX, LaTeX, LaTeX2HTML) are installed it is as easy
3561 as changing into the doc directory and typing
3565 \begin_inset Quotes srd
3569 \begin_inset Quotes srd
3576 You're invited to make changes and additions to this manual (sdcc/doc/sdccman.ly
3579 \begin_inset LatexCommand \url{http://www.lyx.org}
3583 as editor this is straightforward.
3584 Prebuilt documentation in html and pdf format is available from
3585 \begin_inset LatexCommand \url{http://sdcc.sf.net/snap.php}
3592 Reading the Documentation
3595 Currently reading the document in pdf format is recommended, as for unknown
3596 reason the hyperlinks are working there whereas in the html version they
3603 If you should know why please drop us a note
3609 You'll find the pdf version
3610 \begin_inset LatexCommand \index{PDF version of this document}
3615 \begin_inset LatexCommand \url{http://sdcc.sf.net/doc/sdccman.pdf}
3623 \begin_inset LatexCommand \index{HTML version of this document}
3628 \begin_inset LatexCommand \url{http://sdcc.sf.net/doc/sdccman.html/index.html}
3634 This documentation is in some aspects different from a commercial documentation:
3638 It tries to document SDCC for several processor architectures in one document
3639 (commercially these probably would be separate documents/products).
3641 \begin_inset LatexCommand \index{Status of documentation}
3645 currently matches SDCC for mcs51 and DS390 best and does give too few informati
3647 Z80, PIC14, PIC16 and HC08.
3650 There are many references pointing away from this documentation.
3651 Don't let this distract you.
3653 was a reference like
3654 \begin_inset LatexCommand \url{http://www.opencores.org}
3658 together with a statement
3659 \begin_inset Quotes sld
3662 some processors which are targetted by SDCC can be implemented in a
3679 \begin_inset LatexCommand \index{fpga (field programmable gate array)}
3684 \begin_inset Quotes srd
3687 we expect you to have a quick look there and come back.
3688 If you read this you are on the right track.
3691 Some sections attribute more space to problems, restrictions and warnings
3692 than to the solution.
3695 The installation section and the section about the debugger is intimidating.
3698 There are still lots of typos and there are more different writing styles
3702 Testing the SDCC Compiler
3703 \begin_inset LatexCommand \label{sec:Testing-the-SDCC}
3710 The first thing you should do after installing your SDCC compiler is to
3726 \begin_inset LatexCommand \index{version}
3733 at the prompt, and the program should run and tell you the version.
3734 If it doesn't run, or gives a message about not finding sdcc program, then
3735 you need to check over your installation.
3736 Make sure that the sdcc bin directory is in your executable search path
3737 defined by the PATH environment setting (
3742 \begin_inset LatexCommand \ref{sub:Install-Trouble-shooting}
3749 Install trouble-shooting for suggestions
3752 Make sure that the sdcc program is in the bin folder, if not perhaps something
3753 did not install correctly.
3761 is commonly installed as described in section
3762 \begin_inset Quotes sld
3765 Install and search paths
3766 \begin_inset Quotes srd
3775 Make sure the compiler works on a very simple example.
3776 Type in the following test.c program using your favorite
3802 Compile this using the following command:
3811 If all goes well, the compiler will generate a test.asm and test.rel file.
3812 Congratulations, you've just compiled your first program with SDCC.
3813 We used the -c option to tell SDCC not to link the generated code, just
3814 to keep things simple for this step.
3822 The next step is to try it with the linker.
3832 If all goes well the compiler will link with the libraries and produce
3833 a test.ihx output file.
3838 (no test.ihx, and the linker generates warnings), then the problem is most
3847 usr/local/share/sdcc/lib directory
3854 \begin_inset LatexCommand \ref{sub:Install-Trouble-shooting}
3861 Install trouble-shooting for suggestions).
3869 The final test is to ensure
3877 header files and libraries.
3878 Edit test.c and change it to the following:
3895 strcpy(str1, "testing");
3902 Compile this by typing
3909 This should generate a test.ihx output file, and it should give no warnings
3910 such as not finding the string.h file.
3911 If it cannot find the string.h file, then the problem is that
3915 cannot find the /usr/local/share/sdcc/include directory
3922 \begin_inset LatexCommand \ref{sub:Install-Trouble-shooting}
3929 Install trouble-shooting section for suggestions).
3947 \begin_inset LatexCommand \index{-\/-print-search-dirs}
3951 to find exactly where SDCC is looking for the include and lib files.
3954 Install Trouble-shooting
3955 \begin_inset LatexCommand \label{sub:Install-Trouble-shooting}
3960 \begin_inset LatexCommand \index{Install trouble-shooting}
3967 If SDCC does not build correctly
3970 A thing to try is starting from scratch by unpacking the .tgz source package
3971 again in an empty directory.
3979 ./configure 2>&1 | tee configure.log
3993 make 2>&1 | tee make.log
4000 If anything goes wrong, you can review the log files to locate the problem.
4001 Or a relevant part of this can be attached to an email that could be helpful
4002 when requesting help from the mailing list.
4006 \begin_inset Quotes sld
4010 \begin_inset Quotes srd
4017 \begin_inset Quotes sld
4021 \begin_inset Quotes srd
4024 command is a script that analyzes your system and performs some configuration
4025 to ensure the source package compiles on your system.
4026 It will take a few minutes to run, and will compile a few tests to determine
4027 what compiler features are installed.
4031 \begin_inset Quotes sld
4035 \begin_inset Quotes srd
4041 This runs the GNU make tool, which automatically compiles all the source
4042 packages into the final installed binary executables.
4046 \begin_inset Quotes sld
4050 \begin_inset Quotes erd
4056 This will install the compiler, other executables libraries and include
4057 files into the appropriate directories.
4059 \begin_inset LatexCommand \ref{sub:Install-paths}
4065 \begin_inset LatexCommand \ref{sub:Search-Paths}
4070 about install and search paths.
4072 On most systems you will need super-user privileges to do this.
4078 SDCC is not just a compiler, but a collection of tools by various developers.
4079 These include linkers, assemblers, simulators and other components.
4080 Here is a summary of some of the components.
4081 Note that the included simulator and assembler have separate documentation
4082 which you can find in the source package in their respective directories.
4083 As SDCC grows to include support for other processors, other packages from
4084 various developers are included and may have their own sets of documentation.
4088 You might want to look at the files which are installed in <installdir>.
4089 At the time of this writing, we find the following programs for gcc-builds:
4093 In <installdir>/bin:
4096 sdcc - The compiler.
4099 sdcpp - The C preprocessor.
4102 asx8051 - The assembler for 8051 type processors.
4109 as-gbz80 - The Z80 and GameBoy Z80 assemblers.
4112 aslink -The linker for 8051 type processors.
4119 link-gbz80 - The Z80 and GameBoy Z80 linkers.
4122 s51 - The ucSim 8051 simulator.
4125 sdcdb - The source debugger.
4128 packihx - A tool to pack (compress) Intel hex files.
4131 In <installdir>/share/sdcc/include
4137 In <installdir>/share/sdcc/lib
4140 the subdirs src and small, large, z80, gbz80 and ds390 with the precompiled
4144 In <installdir>/share/sdcc/doc
4150 As development for other processors proceeds, this list will expand to include
4151 executables to support processors like AVR, PIC, etc.
4157 This is the actual compiler, it in turn uses the c-preprocessor and invokes
4158 the assembler and linkage editor.
4161 sdcpp - The C-Preprocessor
4165 \begin_inset LatexCommand \index{sdcpp (preprocessor)}
4169 is a modified version of the GNU preprocessor.
4170 The C preprocessor is used to pull in #include sources, process #ifdef
4171 statements, #defines and so on.
4182 - The Assemblers and Linkage Editors
4185 This is retargettable assembler & linkage editor, it was developed by Alan
4187 John Hartman created the version for 8051, and I (Sandeep) have made some
4188 enhancements and bug fixes for it to work properly with SDCC.
4195 \begin_inset LatexCommand \index{s51}
4199 is a freeware, opensource simulator developed by Daniel Drotos.
4200 The simulator is built as part of the build process.
4201 For more information visit Daniel's web site at:
4202 \begin_inset LatexCommand \url{http://mazsola.iit.uni-miskolc.hu/~drdani/embedded/s51}
4207 It currently supports the core mcs51, the Dallas DS80C390 and the Phillips
4211 sdcdb - Source Level Debugger
4215 \begin_inset LatexCommand \index{sdcdb (debugger)}
4219 is the companion source level debugger.
4220 More about sdcdb in section
4221 \begin_inset LatexCommand \ref{cha:Debugging-with-SDCDB}
4226 The current version of the debugger uses Daniel's Simulator S51
4227 \begin_inset LatexCommand \index{s51}
4231 , but can be easily changed to use other simulators.
4241 Single Source File Projects
4244 For single source file 8051 projects the process is very simple.
4245 Compile your programs with the following command
4248 "sdcc sourcefile.c".
4252 This will compile, assemble and link your source file.
4253 Output files are as follows:
4257 \begin_inset LatexCommand \index{<file>.asm}
4262 \begin_inset LatexCommand \index{Assembler source}
4266 file created by the compiler
4270 \begin_inset LatexCommand \index{<file>.lst}
4275 \begin_inset LatexCommand \index{Assembler listing}
4279 file created by the Assembler
4283 \begin_inset LatexCommand \index{<file>.rst}
4288 \begin_inset LatexCommand \index{Assembler listing}
4292 file updated with linkedit information, created by linkage editor
4296 \begin_inset LatexCommand \index{<file>.sym}
4301 \begin_inset LatexCommand \index{Symbol listing}
4305 for the sourcefile, created by the assembler
4309 \begin_inset LatexCommand \index{<file>.rel}
4314 \begin_inset LatexCommand \index{<file>.o}
4319 \begin_inset LatexCommand \index{Object file}
4323 created by the assembler, input to Linkage editor
4327 \begin_inset LatexCommand \index{<file>.map}
4332 \begin_inset LatexCommand \index{Memory map}
4336 for the load module, created by the Linker
4340 \begin_inset LatexCommand \index{<file>.mem}
4344 - A file with a summary of the memory usage
4348 \begin_inset LatexCommand \index{<file>.ihx}
4352 - The load module in Intel hex format
4353 \begin_inset LatexCommand \index{Intel hex format}
4357 (you can select the Motorola S19 format
4358 \begin_inset LatexCommand \index{Motorola S19 format}
4373 \begin_inset LatexCommand \index{-\/-out-fmt-s19}
4378 If you need another format you might want to use
4385 \begin_inset LatexCommand \index{objdump (tool)}
4396 \begin_inset LatexCommand \index{srecord (bin, hex, ... tool)}
4401 Both formats are documented in the documentation of srecord
4402 \begin_inset LatexCommand \index{srecord (bin, hex, ... tool)}
4410 \begin_inset LatexCommand \index{<file>.adb}
4414 - An intermediate file containing debug information needed to create the
4426 \begin_inset LatexCommand \index{-\/-debug}
4434 \begin_inset LatexCommand \index{<file>.cdb}
4438 - An optional file (with -
4448 -debug) containing debug information.
4449 The format is documented in cdbfileformat.pdf
4454 \begin_inset LatexCommand \index{<file> (no extension)}
4458 An optional AOMF or AOMF51
4459 \begin_inset LatexCommand \index{AOMF, AOMF51}
4463 file containing debug information (generated with option -
4490 ormat is commonly used by third party tools (debuggers
4491 \begin_inset LatexCommand \index{Debugger}
4495 , simulators, emulators)
4499 \begin_inset LatexCommand \index{<file>.dump*}
4503 - Dump file to debug the compiler it self (generated with option -
4513 -dumpall) (see section
4514 \begin_inset LatexCommand \ref{sub:Intermediate-Dump-Options}
4520 \begin_inset LatexCommand \ref{sub:The-anatomy-of}
4526 \begin_inset Quotes sld
4529 Anatomy of the compiler
4530 \begin_inset Quotes srd
4536 Projects with Multiple Source Files
4539 SDCC can compile only ONE file at a time.
4540 Let us for example assume that you have a project containing the following
4545 foo1.c (contains some functions)
4547 foo2.c (contains some more functions)
4549 foomain.c (contains more functions and the function main)
4557 The first two files will need to be compiled separately with the commands:
4589 Then compile the source file containing the
4594 \begin_inset LatexCommand \index{Linker}
4598 the files together with the following command:
4606 foomain.c\SpecialChar ~
4607 foo1.rel\SpecialChar ~
4612 \begin_inset LatexCommand \index{<file>.rel}
4624 can be separately compiled as well:
4635 sdcc foomain.rel foo1.rel foo2.rel
4642 The file containing the
4657 file specified in the command line, since the linkage editor processes
4658 file in the order they are presented to it.
4659 The linker is invoked from SDCC using a script file with extension .lnk
4660 \begin_inset LatexCommand \index{<file>.lnk}
4665 You can view this file to troubleshoot linking problems such as those arising
4666 from missing libraries.
4669 Projects with Additional Libraries
4670 \begin_inset LatexCommand \index{Libraries}
4677 Some reusable routines may be compiled into a library, see the documentation
4678 for the assembler and linkage editor (which are in <installdir>/share/sdcc/doc)
4682 \begin_inset LatexCommand \index{<file>.lib}
4689 Libraries created in this manner can be included in the command line.
4690 Make sure you include the -L <library-path> option to tell the linker where
4691 to look for these files if they are not in the current directory.
4692 Here is an example, assuming you have the source file
4704 (if that is not the same as your current project):
4711 sdcc foomain.c foolib.lib -L mylib
4722 must be an absolute path name.
4726 The most efficient way to use libraries is to keep separate modules in separate
4728 The lib file now should name all the modules.rel
4729 \begin_inset LatexCommand \index{<file>.rel}
4734 For an example see the standard library file
4738 in the directory <installdir>/share/lib/small.
4741 Using sdcclib to Create and Manage Libraries
4742 \begin_inset LatexCommand \index{sdcclib}
4749 Alternatively, instead of having a .rel file for each entry on the library
4750 file as described in the preceding section, sdcclib can be used to embed
4751 all the modules belonging to such library in the library file itself.
4752 This results in a larger library file, but it greatly reduces the number
4753 of disk files accessed by the linker.
4754 Additionally, the packed library file contains an index of all include
4755 modules and symbols that significantly speeds up the linking process.
4756 To display a list of options supported by sdcclib type:
4765 \begin_inset LatexCommand \index{sdcclib}
4776 To create a new library file, start by compiling all the required modules.
4814 This will create files _divsint.rel, _divuint.rel, _modsint.rel, _moduint.rel,
4816 The next step is to add the .rel files to the library file:
4824 sdcclib libint.lib _divsint.rel
4827 \begin_inset LatexCommand \index{sdcclib}
4837 sdcclib libint.lib _divuint.rel
4843 sdcclib libint.lib _modsint.rel
4849 sdcclib libint.lib _moduint.rel
4855 sdcclib libint.lib _mulint.rel
4862 If the file already exists in the library, it will be replaced.
4863 To see what modules and symbols are included in the library, options -s
4864 and -m are available.
4872 sdcclib -s libint.lib
4875 \begin_inset LatexCommand \index{sdcclib}
4985 If the source files are compiled using -
4996 \begin_inset LatexCommand \index{-\/-debug}
5000 , the corresponding debug information file .adb will be include in the library
5002 The library files created with sdcclib are plain text files, so they can
5003 be viewed with a text editor.
5004 It is not recomended to modify a library file created with sdcclib using
5005 a text editor, as there are file indexes numbers located accross the file
5006 used by the linker to quickly locate the required module to link.
5007 Once a .rel file (as well as a .adb file) is added to a library using sdcclib,
5008 it can be safely deleted, since all the information required for linking
5009 is embedded in the library file itself.
5010 Library files created using sdcclib are used as described in the preceding
5014 Command Line Options
5015 \begin_inset LatexCommand \index{Command Line Options}
5022 Processor Selection Options
5023 \begin_inset LatexCommand \index{Options processor selection}
5028 \begin_inset LatexCommand \index{Processor selection options}
5034 \labelwidthstring 00.00.0000
5039 \begin_inset LatexCommand \index{-mmcs51}
5045 Generate code for the Intel MCS51
5046 \begin_inset LatexCommand \index{MCS51}
5050 family of processors.
5051 This is the default processor target.
5053 \labelwidthstring 00.00.0000
5058 \begin_inset LatexCommand \index{-mds390}
5064 Generate code for the Dallas DS80C390
5065 \begin_inset LatexCommand \index{DS80C390}
5071 \labelwidthstring 00.00.0000
5076 \begin_inset LatexCommand \index{-mds400}
5082 Generate code for the Dallas DS80C400
5083 \begin_inset LatexCommand \index{DS80C400}
5089 \labelwidthstring 00.00.0000
5094 \begin_inset LatexCommand \index{-mhc08}
5100 Generate code for the Freescale/Motorola HC08
5101 \begin_inset LatexCommand \index{HC08}
5105 family of processors.
5107 \labelwidthstring 00.00.0000
5112 \begin_inset LatexCommand \index{-mz80}
5118 Generate code for the Zilog Z80
5119 \begin_inset LatexCommand \index{Z80}
5123 family of processors.
5125 \labelwidthstring 00.00.0000
5130 \begin_inset LatexCommand \index{-mgbz80}
5136 Generate code for the GameBoy Z80
5137 \begin_inset LatexCommand \index{gbz80 (GameBoy Z80)}
5141 processor (Not actively maintained).
5143 \labelwidthstring 00.00.0000
5148 \begin_inset LatexCommand \index{-mavr}
5154 Generate code for the Atmel AVR
5155 \begin_inset LatexCommand \index{AVR}
5159 processor (In development, not complete).
5160 AVR users should probably have a look at winavr
5161 \begin_inset LatexCommand \url{http://sourceforge.net/projects/winavr}
5166 \begin_inset LatexCommand \url{http://www.avrfreaks.net/index.php?name=PNphpBB2&file=index}
5173 I think it is fair to direct users there for now.
5174 Open source is also about avoiding unnecessary work .
5175 But I didn't find the 'official' link.
5177 \labelwidthstring 00.00.0000
5182 \begin_inset LatexCommand \index{-mpic14}
5188 Generate code for the Microchip PIC 14
5189 \begin_inset LatexCommand \index{PIC14}
5193 -bit processors (p16f84 and variants.
5194 In development, not complete).
5197 p16f627 p16f628 p16f84 p16f873 p16f877?
5199 \labelwidthstring 00.00.0000
5204 \begin_inset LatexCommand \index{-mpic16}
5210 Generate code for the Microchip PIC 16
5211 \begin_inset LatexCommand \index{PIC16}
5215 -bit processors (p18f452 and variants.
5216 In development, not complete).
5218 \labelwidthstring 00.00.0000
5224 Generate code for the Toshiba TLCS-900H
5225 \begin_inset LatexCommand \index{TLCS-900H}
5229 processor (Not maintained, not complete).
5231 \labelwidthstring 00.00.0000
5236 \begin_inset LatexCommand \index{-mxa51}
5242 Generate code for the Phillips XA51
5243 \begin_inset LatexCommand \index{XA51}
5247 processor (Not maintained, not complete).
5250 Preprocessor Options
5251 \begin_inset LatexCommand \index{Options preprocessor}
5256 \begin_inset LatexCommand \index{Preprocessor options}
5261 \begin_inset LatexCommand \index{sdcpp (preprocessor)}
5267 \labelwidthstring 00.00.0000
5272 \begin_inset LatexCommand \index{-I<path>}
5278 The additional location where the pre processor will look for <..h> or
5279 \begin_inset Quotes eld
5283 \begin_inset Quotes erd
5288 \labelwidthstring 00.00.0000
5293 \begin_inset LatexCommand \index{-D<macro[=value]>}
5299 Command line definition of macros.
5300 Passed to the preprocessor.
5302 \labelwidthstring 00.00.0000
5307 \begin_inset LatexCommand \index{-M}
5313 Tell the preprocessor to output a rule suitable for make describing the
5314 dependencies of each object file.
5315 For each source file, the preprocessor outputs one make-rule whose target
5316 is the object file name for that source file and whose dependencies are
5317 all the files `#include'd in it.
5318 This rule may be a single line or may be continued with `
5320 '-newline if it is long.
5321 The list of rules is printed on standard output instead of the preprocessed
5324 \begin_inset LatexCommand \index{-E}
5330 \labelwidthstring 00.00.0000
5335 \begin_inset LatexCommand \index{-C}
5341 Tell the preprocessor not to discard comments.
5342 Used with the `-E' option.
5344 \labelwidthstring 00.00.0000
5349 \begin_inset LatexCommand \index{-MM}
5360 Like `-M' but the output mentions only the user header files included with
5362 \begin_inset Quotes eld
5366 System header files included with `#include <file>' are omitted.
5368 \labelwidthstring 00.00.0000
5373 \begin_inset LatexCommand \index{-Aquestion(answer)}
5379 Assert the answer answer for question, in case it is tested with a preprocessor
5380 conditional such as `#if #question(answer)'.
5381 `-A-' disables the standard assertions that normally describe the target
5384 \labelwidthstring 00.00.0000
5389 \begin_inset LatexCommand \index{-Umacro}
5395 Undefine macro macro.
5396 `-U' options are evaluated after all `-D' options, but before any `-include'
5397 and `-imacros' options.
5399 \labelwidthstring 00.00.0000
5404 \begin_inset LatexCommand \index{-dM}
5410 Tell the preprocessor to output only a list of the macro definitions that
5411 are in effect at the end of preprocessing.
5412 Used with the `-E' option.
5414 \labelwidthstring 00.00.0000
5419 \begin_inset LatexCommand \index{-dD}
5425 Tell the preprocessor to pass all macro definitions into the output, in
5426 their proper sequence in the rest of the output.
5428 \labelwidthstring 00.00.0000
5433 \begin_inset LatexCommand \index{-dN}
5444 Like `-dD' except that the macro arguments and contents are omitted.
5445 Only `#define name' is included in the output.
5447 \labelwidthstring 00.00.0000
5452 preprocessorOption[,preprocessorOption]
5455 \begin_inset LatexCommand \index{-Wp preprocessorOption[,preprocessorOption]}
5460 Pass the preprocessorOption to the preprocessor
5465 \begin_inset LatexCommand \index{sdcpp (preprocessor)}
5470 SDCC uses an adapted version of the preprocessor cpp of the GNU Compiler
5471 Collection (gcc), if you need more dedicated options please refer to the
5473 \begin_inset LatexCommand \htmlurl{http://www.gnu.org/software/gcc/onlinedocs/}
5481 \begin_inset LatexCommand \index{Options linker}
5486 \begin_inset LatexCommand \index{Linker options}
5492 \labelwidthstring 00.00.0000
5512 \begin_inset LatexCommand \index{-\/-lib-path <path>}
5517 \begin_inset LatexCommand \index{-L -\/-lib-path}
5524 <absolute path to additional libraries> This option is passed to the linkage
5525 editor's additional libraries
5526 \begin_inset LatexCommand \index{Libraries}
5531 The path name must be absolute.
5532 Additional library files may be specified in the command line.
5533 See section Compiling programs for more details.
5535 \labelwidthstring 00.00.0000
5552 \begin_inset LatexCommand \index{-\/-xram-loc <Value>}
5557 <Value> The start location of the external ram
5558 \begin_inset LatexCommand \index{xdata (mcs51, ds390 storage class)}
5562 , default value is 0.
5563 The value entered can be in Hexadecimal or Decimal format, e.g.: -
5573 -xram-loc 0x8000 or -
5585 \labelwidthstring 00.00.0000
5602 \begin_inset LatexCommand \index{-\/-code-loc <Value>}
5607 <Value> The start location of the code
5608 \begin_inset LatexCommand \index{code}
5612 segment, default value 0.
5613 Note when this option is used the interrupt vector table is also relocated
5614 to the given address.
5615 The value entered can be in Hexadecimal or Decimal format, e.g.: -
5625 -code-loc 0x8000 or -
5637 \labelwidthstring 00.00.0000
5654 \begin_inset LatexCommand \index{-\/-stack-loc <Value>}
5659 <Value> By default the stack
5660 \begin_inset LatexCommand \index{stack}
5664 is placed after the data segment.
5665 Using this option the stack can be placed anywhere in the internal memory
5667 The value entered can be in Hexadecimal or Decimal format, e.g.
5678 -stack-loc 0x20 or -
5689 Since the sp register is incremented before a push or call, the initial
5690 sp will be set to one byte prior the provided value.
5691 The provided value should not overlap any other memory areas such as used
5692 register banks or the data segment and with enough space for the current
5710 \begin_inset LatexCommand \index{-\/-pack-iram}
5714 option (which is now a default setting) will override this setting, so
5715 you should also specify the
5731 \begin_inset LatexCommand \index{-\/-no-pack-iram}
5735 option if you need to manually place the stack.
5737 \labelwidthstring 00.00.0000
5754 \begin_inset LatexCommand \index{-\/-data-loc <Value>}
5759 <Value> The start location of the internal ram data
5760 \begin_inset LatexCommand \index{data (mcs51, ds390 storage class)}
5765 The value entered can be in Hexadecimal or Decimal format, eg.
5787 (By default, the start location of the internal ram data segment is set
5788 as low as possible in memory, taking into account the used register banks
5789 and the bit segment at address 0x20.
5790 For example if register banks 0 and 1 are used without bit variables, the
5791 data segment will be set, if -
5801 -data-loc is not used, to location 0x10.)
5803 \labelwidthstring 00.00.0000
5820 \begin_inset LatexCommand \index{-\/-idata-loc <Value>}
5825 <Value> The start location of the indirectly addressable internal ram
5826 \begin_inset LatexCommand \index{idata (mcs51, ds390 storage class)}
5830 of the 8051, default value is 0x80.
5831 The value entered can be in Hexadecimal or Decimal format, eg.
5842 -idata-loc 0x88 or -
5854 \labelwidthstring 00.00.0000
5871 <Value> The start location of the bit
5872 \begin_inset LatexCommand \index{bit}
5876 addressable internal ram of the 8051.
5882 Instead an option can be passed directly to the linker: -Wl\SpecialChar ~
5885 \labelwidthstring 00.00.0000
5900 \begin_inset LatexCommand \index{-\/-out-fmt-ihx}
5909 The linker output (final object code) is in Intel Hex format.
5910 \begin_inset LatexCommand \index{Intel hex format}
5914 This is the default option.
5915 The format itself is documented in the documentation of srecord
5916 \begin_inset LatexCommand \index{srecord (bin, hex, ... tool)}
5922 \labelwidthstring 00.00.0000
5937 \begin_inset LatexCommand \index{-\/-out-fmt-s19}
5946 The linker output (final object code) is in Motorola S19 format
5947 \begin_inset LatexCommand \index{Motorola S19 format}
5952 The format itself is documented in the documentation of srecord.
5954 \labelwidthstring 00.00.0000
5969 \begin_inset LatexCommand \index{-\/-out-fmt-s19}
5978 The linker output (final object code) is in ELF format
5979 \begin_inset LatexCommand \index{ELF format}
5984 (Currently only supported for the HC08 processors)
5986 \labelwidthstring 00.00.0000
5991 linkOption[,linkOption]
5994 \begin_inset LatexCommand \index{-Wl linkOption[,linkOption]}
5999 Pass the linkOption to the linker.
6000 See file sdcc/as/doc/asxhtm.html for more on linker options.
6004 \begin_inset LatexCommand \index{Options MCS51}
6009 \begin_inset LatexCommand \index{MCS51 options}
6015 \labelwidthstring 00.00.0000
6030 \begin_inset LatexCommand \index{-\/-model-small}
6041 Generate code for Small Model programs, see section Memory Models for more
6043 This is the default model.
6045 \labelwidthstring 00.00.0000
6060 \begin_inset LatexCommand \index{-\/-model-large}
6066 Generate code for Large model programs, see section Memory Models for more
6068 If this option is used all source files in the project have to be compiled
6070 It must also be used when invoking the linker.
6072 \labelwidthstring 00.00.0000
6087 \begin_inset LatexCommand \index{-\/-xstack}
6093 Uses a pseudo stack in the first 256 bytes in the external ram for allocating
6094 variables and passing parameters.
6096 \begin_inset LatexCommand \ref{sub:External-Stack}
6101 External Stack for more details.
6103 \labelwidthstring 00.00.0000
6121 \begin_inset LatexCommand \index{-\/-iram-size <Value>}
6125 Causes the linker to check if the internal ram usage is within limits of
6128 \labelwidthstring 00.00.0000
6146 \begin_inset LatexCommand \index{-\/-xram-size <Value>}
6150 Causes the linker to check if the external ram usage is within limits of
6153 \labelwidthstring 00.00.0000
6171 \begin_inset LatexCommand \index{-\/-code-size <Value>}
6175 Causes the linker to check if the code memory usage is within limits of
6178 \labelwidthstring 00.00.0000
6196 \begin_inset LatexCommand \index{-\/-stack-size <Value>}
6200 Causes the linker to check if there is at minimum <Value> bytes for stack.
6202 \labelwidthstring 00.00.0000
6220 \begin_inset LatexCommand \index{-\/-pack-iram}
6224 Causes the linker to use unused register banks for data variables and pack
6225 data, idata and stack together.
6226 This is the default now.
6228 \labelwidthstring 00.00.0000
6246 \begin_inset LatexCommand \index{-\/-no-pack-iram}
6250 Causes the linker to use old style for allocating memory areas.
6253 DS390 / DS400 Options
6254 \begin_inset LatexCommand \index{Options DS390}
6259 \begin_inset LatexCommand \index{DS390 options}
6265 \labelwidthstring 00.00.0000
6282 \begin_inset LatexCommand \index{-\/-model-flat24}
6292 Generate 24-bit flat mode code.
6293 This is the one and only that the ds390 code generator supports right now
6294 and is default when using
6299 See section Memory Models for more details.
6301 \labelwidthstring 00.00.0000
6316 \begin_inset LatexCommand \index{-\/-protect-sp-update}
6322 disable interrupts during ESP:SP updates.
6324 \labelwidthstring 00.00.0000
6341 \begin_inset LatexCommand \index{-\/-stack-10bit}
6345 Generate code for the 10 bit stack mode of the Dallas DS80C390 part.
6346 This is the one and only that the ds390 code generator supports right now
6347 and is default when using
6352 In this mode, the stack is located in the lower 1K of the internal RAM,
6353 which is mapped to 0x400000.
6354 Note that the support is incomplete, since it still uses a single byte
6355 as the stack pointer.
6356 This means that only the lower 256 bytes of the potential 1K stack space
6357 will actually be used.
6358 However, this does allow you to reclaim the precious 256 bytes of low RAM
6359 for use for the DATA and IDATA segments.
6360 The compiler will not generate any code to put the processor into 10 bit
6362 It is important to ensure that the processor is in this mode before calling
6363 any re-entrant functions compiled with this option.
6364 In principle, this should work with the
6377 \begin_inset LatexCommand \index{-\/-stack-auto}
6383 option, but that has not been tested.
6384 It is incompatible with the
6397 \begin_inset LatexCommand \index{-\/-xstack}
6404 It also only makes sense if the processor is in 24 bit contiguous addressing
6417 -model-flat24 option
6421 \labelwidthstring 00.00.0000
6436 \begin_inset LatexCommand \index{-\/-stack-probe}
6442 insert call to function __stack_probe at each function prologue.
6444 \labelwidthstring 00.00.0000
6459 \begin_inset LatexCommand \index{-\/-tini-libid}
6465 <nnnn> LibraryID used in -mTININative.
6468 \labelwidthstring 00.00.0000
6483 \begin_inset LatexCommand \index{-\/-use-accelerator}
6489 generate code for DS390 Arithmetic Accelerator.
6494 \begin_inset LatexCommand \index{Options Z80}
6499 \begin_inset LatexCommand \index{Z80 options}
6505 \labelwidthstring 00.00.0000
6522 \begin_inset LatexCommand \index{-\/-callee-saves-bc}
6532 Force a called function to always save BC.
6534 \labelwidthstring 00.00.0000
6551 \begin_inset LatexCommand \index{-\/-no-std-crt0}
6555 When linking, skip the standard crt0.o object file.
6556 You must provide your own crt0.o for your system when linking.
6560 Optimization Options
6561 \begin_inset LatexCommand \index{Options optimization}
6566 \begin_inset LatexCommand \index{Optimization options}
6572 \labelwidthstring 00.00.0000
6587 \begin_inset LatexCommand \index{-\/-nogcse}
6593 Will not do global subexpression elimination, this option may be used when
6594 the compiler creates undesirably large stack/data spaces to store compiler
6604 \begin_inset LatexCommand \index{sloc (spill location)}
6609 A warning message will be generated when this happens and the compiler
6610 will indicate the number of extra bytes it allocated.
6611 It is recommended that this option NOT be used, #pragma\SpecialChar ~
6613 \begin_inset LatexCommand \index{\#pragma nogcse}
6617 can be used to turn off global subexpression elimination
6618 \begin_inset LatexCommand \index{Subexpression elimination}
6622 for a given function only.
6624 \labelwidthstring 00.00.0000
6639 \begin_inset LatexCommand \index{-\/-noinvariant}
6645 Will not do loop invariant optimizations, this may be turned off for reasons
6646 explained for the previous option.
6647 For more details of loop optimizations performed see Loop Invariants in
6649 \begin_inset LatexCommand \ref{sub:Loop-Optimizations}
6654 It is recommended that this option NOT be used, #pragma\SpecialChar ~
6656 \begin_inset LatexCommand \index{\#pragma noinvariant}
6660 can be used to turn off invariant optimizations for a given function only.
6662 \labelwidthstring 00.00.0000
6677 \begin_inset LatexCommand \index{-\/-noinduction}
6683 Will not do loop induction optimizations, see section strength reduction
6685 It is recommended that this option is NOT used, #pragma\SpecialChar ~
6687 \begin_inset LatexCommand \index{\#pragma noinduction}
6691 can be used to turn off induction optimizations for a given function only.
6693 \labelwidthstring 00.00.0000
6708 \begin_inset LatexCommand \index{-\/-nojtbound}
6719 Will not generate boundary condition check when switch statements
6720 \begin_inset LatexCommand \index{switch statement}
6724 are implemented using jump-tables.
6726 \begin_inset LatexCommand \ref{sub:'switch'-Statements}
6731 Switch Statements for more details.
6732 It is recommended that this option is NOT used, #pragma\SpecialChar ~
6734 \begin_inset LatexCommand \index{\#pragma nojtbound}
6738 can be used to turn off boundary checking for jump tables for a given function
6741 \labelwidthstring 00.00.0000
6756 \begin_inset LatexCommand \index{-\/-noloopreverse}
6765 Will not do loop reversal
6766 \begin_inset LatexCommand \index{Loop reversing}
6772 \labelwidthstring 00.00.0000
6789 \begin_inset LatexCommand \index{-\/-nolabelopt }
6793 Will not optimize labels (makes the dumpfiles more readable).
6795 \labelwidthstring 00.00.0000
6810 \begin_inset LatexCommand \index{-\/-no-xinit-opt}
6816 Will not memcpy initialized data from code space into xdata space.
6817 This saves a few bytes in code space if you don't have initialized data
6818 \begin_inset LatexCommand \index{Variable initialization}
6824 \labelwidthstring 00.00.0000
6839 \begin_inset LatexCommand \index{-\/-nooverlay}
6845 The compiler will not overlay parameters and local variables of any function,
6846 see section Parameters and local variables for more details.
6848 \labelwidthstring 00.00.0000
6863 \begin_inset LatexCommand \index{-\/-no-peep}
6869 Disable peep-hole optimization.
6871 \labelwidthstring 00.00.0000
6888 \begin_inset LatexCommand \index{-\/-peep-file}
6893 <filename> This option can be used to use additional rules to be used by
6894 the peep hole optimizer.
6896 \begin_inset LatexCommand \ref{sub:Peephole-Optimizer}
6901 Peep Hole optimizations for details on how to write these rules.
6903 \labelwidthstring 00.00.0000
6918 \begin_inset LatexCommand \index{-\/-peep-asm}
6924 Pass the inline assembler code through the peep hole optimizer.
6925 This can cause unexpected changes to inline assembler code, please go through
6926 the peephole optimizer
6927 \begin_inset LatexCommand \index{Peephole optimizer}
6931 rules defined in the source file tree '<target>/peeph.def' before using
6934 \labelwidthstring 00.00.0000
6949 \begin_inset LatexCommand \index{-\/-opt-code-speed}
6955 The compiler will optimize code generation towards fast code, possibly
6956 at the expense of code size.
6958 \labelwidthstring 00.00.0000
6973 \begin_inset LatexCommand \index{-\/-opt-code-size}
6979 The compiler will optimize code generation towards compact code, possibly
6980 at the expense of code speed.
6984 \begin_inset LatexCommand \index{Options other}
6990 \labelwidthstring 00.00.0000
7006 \begin_inset LatexCommand \index{-\/-compile-only}
7011 \begin_inset LatexCommand \index{-c -\/-compile-only}
7017 will compile and assemble the source, but will not call the linkage editor.
7019 \labelwidthstring 00.00.0000
7038 \begin_inset LatexCommand \index{-\/-c1mode}
7044 reads the preprocessed source from standard input and compiles it.
7045 The file name for the assembler output must be specified using the -o option.
7047 \labelwidthstring 00.00.0000
7052 \begin_inset LatexCommand \index{-E}
7058 Run only the C preprocessor.
7059 Preprocess all the C source files specified and output the results to standard
7062 \labelwidthstring 00.00.0000
7068 \begin_inset LatexCommand \index{-o <path/file>}
7074 The output path resp.
7075 file where everything will be placed.
7076 If the parameter is a path, it must have a trailing slash (or backslash
7077 for the Windows binaries) to be recognized as a path.
7080 \labelwidthstring 00.00.0000
7095 \begin_inset LatexCommand \index{-\/-stack-auto}
7106 All functions in the source file will be compiled as
7111 \begin_inset LatexCommand \index{reentrant}
7116 the parameters and local variables will be allocated on the stack
7117 \begin_inset LatexCommand \index{stack}
7123 \begin_inset LatexCommand \ref{sec:Parameters-and-Local-Variables}
7127 Parameters and Local Variables for more details.
7128 If this option is used all source files in the project should be compiled
7130 It automatically implies --int-long-reent and --float-reent.
7133 \labelwidthstring 00.00.0000
7148 \begin_inset LatexCommand \index{-\/-callee-saves}
7152 function1[,function2][,function3]....
7155 The compiler by default uses a caller saves convention for register saving
7156 across function calls, however this can cause unnecessary register pushing
7157 & popping when calling small functions from larger functions.
7158 This option can be used to switch the register saving convention for the
7159 function names specified.
7160 The compiler will not save registers when calling these functions, no extra
7161 code will be generated at the entry & exit (function prologue
7164 \begin_inset LatexCommand \index{function prologue}
7173 \begin_inset LatexCommand \index{function epilogue}
7179 ) for these functions to save & restore the registers used by these functions,
7180 this can SUBSTANTIALLY reduce code & improve run time performance of the
7182 In the future the compiler (with inter procedural analysis) will be able
7183 to determine the appropriate scheme to use for each function call.
7184 DO NOT use this option for built-in functions such as _mulint..., if this
7185 option is used for a library function the appropriate library function
7186 needs to be recompiled with the same option.
7187 If the project consists of multiple source files then all the source file
7188 should be compiled with the same -
7198 -callee-saves option string.
7199 Also see #pragma\SpecialChar ~
7201 \begin_inset LatexCommand \index{\#pragma callee\_saves}
7207 \labelwidthstring 00.00.0000
7222 \begin_inset LatexCommand \index{-\/-debug}
7231 When this option is used the compiler will generate debug information.
7232 The debug information collected in a file with .cdb extension can be used
7234 For more information see documentation for SDCDB.
7235 Another file with no extension contains debug information in AOMF or AOMF51
7236 \begin_inset LatexCommand \index{AOMF, AOMF51}
7240 format which is commonly used by third party tools.
7242 \labelwidthstring 00.00.0000
7247 \begin_inset LatexCommand \index{-S}
7258 Stop after the stage of compilation proper; do not assemble.
7259 The output is an assembler code file for the input file specified.
7261 \labelwidthstring 00.00.0000
7276 \begin_inset LatexCommand \index{-\/-int-long-reent}
7282 Integer (16 bit) and long (32 bit) libraries have been compiled as reentrant.
7283 Note by default these libraries are compiled as non-reentrant.
7284 See section Installation for more details.
7286 \labelwidthstring 00.00.0000
7301 \begin_inset LatexCommand \index{-\/-cyclomatic}
7310 This option will cause the compiler to generate an information message for
7311 each function in the source file.
7312 The message contains some
7316 information about the function.
7317 The number of edges and nodes the compiler detected in the control flow
7318 graph of the function, and most importantly the
7320 cyclomatic complexity
7321 \begin_inset LatexCommand \index{Cyclomatic complexity}
7327 see section on Cyclomatic Complexity for more details.
7329 \labelwidthstring 00.00.0000
7344 \begin_inset LatexCommand \index{-\/-float-reent}
7350 Floating point library is compiled as reentrant
7351 \begin_inset LatexCommand \index{reentrant}
7356 See section Installation for more details.
7358 \labelwidthstring 00.00.0000
7373 \begin_inset LatexCommand \index{-\/-main-return}
7379 This option can be used if the code generated is called by a monitor program
7380 or if the main routine includes an endless loop.
7381 This option might result in slightly smaller code and save two bytes of
7383 The return from the 'main'
7384 \begin_inset LatexCommand \index{main return}
7388 function will return to the function calling main.
7389 The default setting is to lock up i.e.
7396 \labelwidthstring 00.00.0000
7411 \begin_inset LatexCommand \index{-\/-nostdinc}
7417 This will prevent the compiler from passing on the default include path
7418 to the preprocessor.
7420 \labelwidthstring 00.00.0000
7435 \begin_inset LatexCommand \index{-\/-nostdlib}
7441 This will prevent the compiler from passing on the default library
7442 \begin_inset LatexCommand \index{Libraries}
7448 \labelwidthstring 00.00.0000
7463 \begin_inset LatexCommand \index{-\/-verbose}
7469 Shows the various actions the compiler is performing.
7471 \labelwidthstring 00.00.0000
7476 \begin_inset LatexCommand \index{-V}
7482 Shows the actual commands the compiler is executing.
7484 \labelwidthstring 00.00.0000
7499 \begin_inset LatexCommand \index{-\/-no-c-code-in-asm}
7505 Hides your ugly and inefficient c-code from the asm file, so you can always
7506 blame the compiler :)
7508 \labelwidthstring 00.00.0000
7523 \begin_inset LatexCommand \index{-\/-no-peep-comments}
7529 Will not include peep-hole comments in the generated files.
7531 \labelwidthstring 00.00.0000
7546 \begin_inset LatexCommand \index{-\/-i-code-in-asm}
7552 Include i-codes in the asm file.
7553 Sounds like noise but is most helpful for debugging the compiler itself.
7555 \labelwidthstring 00.00.0000
7570 \begin_inset LatexCommand \index{-\/-less-pedantic}
7576 Disable some of the more pedantic warnings
7577 \begin_inset LatexCommand \index{Warnings}
7581 (jwk burps: please be more specific here, please!).
7583 \labelwidthstring 00.00.0000
7597 -disable-warning\SpecialChar ~
7599 \begin_inset LatexCommand \index{-\/-disable-warning}
7605 Disable specific warning with number <nnnn>.
7607 \labelwidthstring 00.00.0000
7622 \begin_inset LatexCommand \index{-\/-print-search-dirs}
7628 Display the directories in the compiler's search path
7630 \labelwidthstring 00.00.0000
7645 \begin_inset LatexCommand \index{-\/-vc}
7651 Display errors and warnings using MSVC style, so you can use SDCC with
7654 \labelwidthstring 00.00.0000
7669 \begin_inset LatexCommand \index{-\/-use-stdout}
7675 Send errors and warnings to stdout instead of stderr.
7677 \labelwidthstring 00.00.0000
7682 asmOption[,asmOption]
7685 \begin_inset LatexCommand \index{-Wa asmOption[,asmOption]}
7690 Pass the asmOption to the assembler
7691 \begin_inset LatexCommand \index{Options assembler}
7696 \begin_inset LatexCommand \index{Assembler options}
7701 See file sdcc/as/doc/asxhtm.html for assembler options.cd
7703 \labelwidthstring 00.00.0000
7718 \begin_inset LatexCommand \index{-\/-std-sdcc89}
7724 Generally follow the C89 standard, but allow SDCC features that conflict
7725 with the standard (default).
7727 \labelwidthstring 00.00.0000
7742 \begin_inset LatexCommand \index{-\/-std-c89}
7748 Follow the C89 standard and disable SDCC features that conflict with the
7751 \labelwidthstring 00.00.0000
7766 \begin_inset LatexCommand \index{-\/-std-sdcc99}
7772 Generally follow the C99 standard, but allow SDCC features that conflict
7773 with the standard (incomplete support).
7775 \labelwidthstring 00.00.0000
7790 \begin_inset LatexCommand \index{-\/-std-sdcc99}
7796 Follow the C99 standard and disable SDCC features that conflict with the
7797 standard (incomplete support).
7799 \labelwidthstring 00.00.0000
7816 \begin_inset LatexCommand \index{-\/-codeseg <Value>}
7821 <Name> The name to be used for the code
7822 \begin_inset LatexCommand \index{code}
7826 segment, default CSEG.
7827 This is useful if you need to tell the compiler to put the code in a special
7828 segment so you can later on tell the linker to put this segment in a special
7830 Can be used for instance when using bank switching to put the code in a
7833 \labelwidthstring 00.00.0000
7850 \begin_inset LatexCommand \index{-\/-constseg <Value>}
7855 <Name> The name to be used for the const
7856 \begin_inset LatexCommand \index{code}
7860 segment, default CONST.
7861 This is useful if you need to tell the compiler to put the const data in
7862 a special segment so you can later on tell the linker to put this segment
7863 in a special place in memory.
7864 Can be used for instance when using bank switching to put the const data
7867 \labelwidthstring 00.00.0000
7879 a SDCC compiler option but if you want
7883 warnings you can use a separate tool dedicated to syntax checking like
7885 \begin_inset LatexCommand \label{lyx:more-pedantic-SPLINT}
7890 \begin_inset LatexCommand \index{lint (syntax checking tool)}
7895 \begin_inset LatexCommand \url{http://www.splint.org}
7900 To make your source files parseable by splint you will have to include
7906 \begin_inset LatexCommand \index{splint (syntax checking tool)}
7910 in your source file and add brackets around extended keywords (like
7913 \begin_inset Quotes sld
7926 \begin_inset Quotes srd
7934 \begin_inset Quotes sld
7937 __interrupt\SpecialChar ~
7939 \begin_inset Quotes srd
7947 Splint has an excellent on line manual at
7948 \begin_inset LatexCommand \url{http://www.splint.org/manual/}
7952 and it's capabilities go beyond pure syntax checking.
7953 You'll need to tell splint the location of SDCC's include files so a typical
7954 command line could look like this:
7958 splint\SpecialChar ~
7960 /usr/local/share/sdcc/include/mcs51/\SpecialChar ~
7965 Intermediate Dump Options
7966 \begin_inset LatexCommand \label{sub:Intermediate-Dump-Options}
7971 \begin_inset LatexCommand \index{Options intermediate dump}
7976 \begin_inset LatexCommand \index{Intermediate dump options}
7983 The following options are provided for the purpose of retargetting and debugging
7985 They provide a means to dump the intermediate code (iCode
7986 \begin_inset LatexCommand \index{iCode}
7990 ) generated by the compiler in human readable form at various stages of
7991 the compilation process.
7992 More on iCodes see chapter
7993 \begin_inset LatexCommand \ref{sub:The-anatomy-of}
7998 \begin_inset Quotes srd
8001 The anatomy of the compiler
8002 \begin_inset Quotes srd
8007 \labelwidthstring 00.00.0000
8022 \begin_inset LatexCommand \index{-\/-dumpraw}
8028 This option will cause the compiler to dump the intermediate code into
8031 <source filename>.dumpraw
8033 just after the intermediate code has been generated for a function, i.e.
8034 before any optimizations are done.
8036 \begin_inset LatexCommand \index{Basic blocks}
8040 at this stage ordered in the depth first number, so they may not be in
8041 sequence of execution.
8043 \labelwidthstring 00.00.0000
8058 \begin_inset LatexCommand \index{-\/-dumpgcse}
8064 Will create a dump of iCode's, after global subexpression elimination
8065 \begin_inset LatexCommand \index{Global subexpression elimination}
8071 <source filename>.dumpgcse.
8073 \labelwidthstring 00.00.0000
8088 \begin_inset LatexCommand \index{-\/-dumpdeadcode}
8094 Will create a dump of iCode's, after deadcode elimination
8095 \begin_inset LatexCommand \index{Dead-code elimination}
8101 <source filename>.dumpdeadcode.
8103 \labelwidthstring 00.00.0000
8118 \begin_inset LatexCommand \index{-\/-dumploop}
8127 Will create a dump of iCode's, after loop optimizations
8128 \begin_inset LatexCommand \index{Loop optimization}
8134 <source filename>.dumploop.
8136 \labelwidthstring 00.00.0000
8151 \begin_inset LatexCommand \index{-\/-dumprange}
8160 Will create a dump of iCode's, after live range analysis
8161 \begin_inset LatexCommand \index{Live range analysis}
8167 <source filename>.dumprange.
8169 \labelwidthstring 00.00.0000
8184 \begin_inset LatexCommand \index{-\/-dumlrange}
8190 Will dump the life ranges
8191 \begin_inset LatexCommand \index{Live range analysis}
8197 \labelwidthstring 00.00.0000
8212 \begin_inset LatexCommand \index{-\/-dumpregassign}
8221 Will create a dump of iCode's, after register assignment
8222 \begin_inset LatexCommand \index{Register assignment}
8228 <source filename>.dumprassgn.
8230 \labelwidthstring 00.00.0000
8245 \begin_inset LatexCommand \index{-\/-dumplrange}
8251 Will create a dump of the live ranges of iTemp's
8253 \labelwidthstring 00.00.0000
8268 \begin_inset LatexCommand \index{-\/-dumpall}
8279 Will cause all the above mentioned dumps to be created.
8282 Redirecting output on Windows Shells
8285 By default SDCC writes it's error messages to
8286 \begin_inset Quotes sld
8290 \begin_inset Quotes srd
8294 To force all messages to
8295 \begin_inset Quotes sld
8299 \begin_inset Quotes srd
8323 \begin_inset LatexCommand \index{-\/-use-stdout}
8328 Additionally, if you happen to have visual studio installed in your windows
8329 machine, you can use it to compile your sources using a custom build and
8345 \begin_inset LatexCommand \index{-\/-vc}
8350 Something like this should work:
8394 -model-large -c $(InputPath)
8397 Environment variables
8398 \begin_inset LatexCommand \index{Environment variables}
8405 SDCC recognizes the following environment variables:
8407 \labelwidthstring 00.00.0000
8412 \begin_inset LatexCommand \index{SDCC\_LEAVE\_SIGNALS}
8418 SDCC installs a signal handler
8419 \begin_inset LatexCommand \index{signal handler}
8423 to be able to delete temporary files after an user break (^C) or an exception.
8424 If this environment variable is set, SDCC won't install the signal handler
8425 in order to be able to debug SDCC.
8427 \labelwidthstring 00.00.0000
8434 \begin_inset LatexCommand \index{TMP, TEMP, TMPDIR}
8440 Path, where temporary files will be created.
8441 The order of the variables is the search order.
8442 In a standard *nix environment these variables are not set, and there's
8443 no need to set them.
8444 On Windows it's recommended to set one of them.
8446 \labelwidthstring 00.00.0000
8451 \begin_inset LatexCommand \index{SDCC\_HOME}
8458 \begin_inset LatexCommand \ref{sub:Install-paths}
8464 \begin_inset Quotes sld
8468 \begin_inset Quotes srd
8473 \labelwidthstring 00.00.0000
8478 \begin_inset LatexCommand \index{SDCC\_INCLUDE}
8485 \begin_inset LatexCommand \ref{sub:Search-Paths}
8491 \begin_inset Quotes sld
8495 \begin_inset Quotes srd
8500 \labelwidthstring 00.00.0000
8505 \begin_inset LatexCommand \index{SDCC\_LIB}
8512 \begin_inset LatexCommand \ref{sub:Search-Paths}
8518 \begin_inset Quotes sld
8522 \begin_inset Quotes srd
8528 There are some more environment variables recognized by SDCC, but these
8529 are solely used for debugging purposes.
8530 They can change or disappear very quickly, and will never be documented.
8533 Storage Class Language Extensions
8536 MCS51/DS390 Storage Class
8537 \begin_inset LatexCommand \index{Storage class}
8544 In addition to the ANSI storage classes SDCC allows the following MCS51
8545 specific storage classes:
8546 \layout Subsubsection
8549 \begin_inset LatexCommand \index{data (mcs51, ds390 storage class)}
8554 \begin_inset LatexCommand \index{\_\_data (mcs51, ds390 storage class)}
8559 \begin_inset LatexCommand \index{near (storage class)}
8564 \begin_inset LatexCommand \index{\_\_near (storage class)}
8575 storage class for the Small Memory model (
8583 can be used synonymously).
8584 Variables declared with this storage class will be allocated in the directly
8585 addressable portion of the internal RAM of a 8051, e.g.:
8590 data unsigned char test_data;
8593 Writing 0x01 to this variable generates the assembly code:
8598 75*00 01\SpecialChar ~
8604 \layout Subsubsection
8607 \begin_inset LatexCommand \index{xdata (mcs51, ds390 storage class)}
8612 \begin_inset LatexCommand \index{\_\_xdata (mcs51, ds390 storage class)}
8617 \begin_inset LatexCommand \index{far (storage class)}
8622 \begin_inset LatexCommand \index{\_\_far (storage class)}
8629 Variables declared with this storage class will be placed in the external
8635 storage class for the Large Memory model, e.g.:
8640 xdata unsigned char test_xdata;
8643 Writing 0x01 to this variable generates the assembly code:
8648 90s00r00\SpecialChar ~
8677 \layout Subsubsection
8680 \begin_inset LatexCommand \index{idata (mcs51, ds390 storage class)}
8685 \begin_inset LatexCommand \index{\_\_idata (mcs51, ds390 storage class)}
8692 Variables declared with this storage class will be allocated into the indirectly
8693 addressable portion of the internal ram of a 8051, e.g.:
8698 idata unsigned char test_idata;
8701 Writing 0x01 to this variable generates the assembly code:
8730 Please note, the first 128 byte of idata physically access the same RAM
8732 The original 8051 had 128 byte idata memory, nowadays most devices have
8733 256 byte idata memory.
8735 \begin_inset LatexCommand \index{stack}
8739 is located in idata memory.
8740 \layout Subsubsection
8743 \begin_inset LatexCommand \index{pdata (mcs51, ds390 storage class)}
8748 \begin_inset LatexCommand \index{\_\_pdata (mcs51, ds390 storage class)}
8755 Paged xdata access is just as straightforward as using the other addressing
8757 It is typically located at the start of xdata and has a maximum size of
8759 The following example writes 0x01 to the pdata variable.
8760 Please note, pdata access physically accesses xdata memory.
8761 The high byte of the address is determined by port P2
8762 \begin_inset LatexCommand \index{P2 (mcs51 sfr)}
8766 (or in case of some 8051 variants by a separate Special Function Register,
8768 \begin_inset LatexCommand \ref{sub:MCS51-variants}
8777 pdata unsigned char test_pdata;
8780 Writing 0x01 to this variable generates the assembly code:
8824 \begin_inset LatexCommand \index{-\/-xstack}
8828 option is used the pdata memory area is followed by the xstack memory area
8829 and the sum of their sizes is limited to 256 bytes.
8830 \layout Subsubsection
8833 \begin_inset LatexCommand \index{code}
8838 \begin_inset LatexCommand \index{\_\_code}
8845 'Variables' declared with this storage class will be placed in the code
8851 code unsigned char test_code;
8854 Read access to this variable generates the assembly code:
8859 90s00r6F\SpecialChar ~
8862 mov dptr,#_test_code
8891 indexed arrays of characters in code memory can be accessed efficiently:
8896 code char test_array[] = {'c','h','e','a','p'};
8899 Read access to this array using an 8-bit unsigned index generates the assembly
8916 90s00r41\SpecialChar ~
8919 mov dptr,#_test_array
8934 \layout Subsubsection
8937 \begin_inset LatexCommand \index{bit}
8942 \begin_inset LatexCommand \index{\_\_bit}
8949 This is a data-type and a storage class specifier.
8950 When a variable is declared as a bit, it is allocated into the bit addressable
8951 memory of 8051, e.g.:
8959 Writing 1 to this variable generates the assembly code:
8975 The bit addressable memory consists of 128 bits which are located from 0x20
8976 to 0x2f in data memory.
8979 Apart from this 8051 specific storage class most architectures support ANSI-C
8981 \begin_inset LatexCommand \index{bitfields}
8991 Not really meant as examples, but nevertheless showing what bitfields are
8992 about: device/include/mc68hc908qy.h and support/regression/tests/bitfields.c
8996 In accordance with ISO/IEC 9899 bits and bitfields without an explicit
8997 signed modifier are implemented as unsigned.
8998 \layout Subsubsection
9001 \begin_inset LatexCommand \index{sfr}
9006 \begin_inset LatexCommand \index{\_\_sfr}
9011 \begin_inset LatexCommand \index{sfr16}
9016 \begin_inset LatexCommand \index{\_\_sfr16}
9021 \begin_inset LatexCommand \index{sfr32}
9026 \begin_inset LatexCommand \index{\_\_sfr32}
9031 \begin_inset LatexCommand \index{\_\_sbit}
9038 Like the bit keyword,
9040 sfr / sfr16 / sfr32 / sbit
9042 signify both a data-type and storage class, they are used to describe the
9063 variables of a 8051, eg:
9069 \begin_inset LatexCommand \index{at}
9074 \begin_inset LatexCommand \index{\_\_at}
9078 0x80 P0;\SpecialChar ~
9079 /* special function register P0 at location 0x80 */
9081 /* 16 bit special function register combination for timer 0 */
9083 /* with the high byte at location 0x8C and the low byte at location 0x8A
9087 \begin_inset LatexCommand \index{at}
9092 \begin_inset LatexCommand \index{\_\_at}
9098 sbit at 0xd7 CY; /* CY (Carry Flag
9099 \begin_inset LatexCommand \index{Flags}
9104 \begin_inset LatexCommand \index{Carry flag}
9111 Special function registers which are located on an address dividable by
9112 8 are bit-addressable, an
9116 addresses a specific bit within these sfr.
9118 16 Bit and 32 bit special function register combinations which require a
9119 certain access order are better not declared using
9128 Allthough SDCC usually accesses them Least Significant Byte (LSB) first,
9129 this is not guaranteed.
9130 \layout Subsubsection
9133 \begin_inset LatexCommand \index{Pointer}
9137 to MCS51/DS390 specific memory spaces
9140 SDCC allows (via language extensions) pointers to explicitly point to any
9141 of the memory spaces
9142 \begin_inset LatexCommand \index{Memory model}
9147 In addition to the explicit pointers, the compiler uses (by default) generic
9148 pointers which can be used to point to any of the memory spaces.
9152 Pointer declaration examples:
9157 /* pointer physically in internal ram pointing to object in external ram
9160 xdata unsigned char * data p;
9164 /* pointer physically in external ram pointing to object in internal ram
9167 data unsigned char * xdata p;
9171 /* pointer physically in code rom pointing to data in xdata space */
9173 xdata unsigned char * code p;
9177 /* pointer physically in code space pointing to data in code space */
9179 code unsigned char * code p;
9183 /* the following is a generic pointer physically located in xdata space
9190 /* the following is a function pointer physically located in data space
9193 char (* data fp)(void);
9196 Well you get the idea.
9201 All unqualified pointers are treated as 3-byte (4-byte for the ds390)
9214 The highest order byte of the
9218 pointers contains the data space information.
9219 Assembler support routines are called whenever data is stored or retrieved
9225 These are useful for developing reusable library
9226 \begin_inset LatexCommand \index{Libraries}
9231 Explicitly specifying the pointer type will generate the most efficient
9233 \layout Subsubsection
9235 Notes on MCS51 memory
9236 \begin_inset LatexCommand \index{MCS51 memory}
9243 The 8051 family of microcontrollers have a minimum of 128 bytes of internal
9244 RAM memory which is structured as follows:
9248 - Bytes 00-1F - 32 bytes to hold up to 4 banks of the registers R0 to R7,
9251 - Bytes 20-2F - 16 bytes to hold 128 bit
9252 \begin_inset LatexCommand \index{bit}
9258 - Bytes 30-7F - 80 bytes for general purpose use.
9263 Additionally some members of the MCS51 family may have up to 128 bytes of
9264 additional, indirectly addressable, internal RAM memory (
9269 \begin_inset LatexCommand \index{idata (mcs51, ds390 storage class)}
9274 \begin_inset LatexCommand \index{\_\_idata (mcs51, ds390 storage class)}
9279 Furthermore, some chips may have some built in external memory (
9284 \begin_inset LatexCommand \index{xdata (mcs51, ds390 storage class)}
9289 \begin_inset LatexCommand \index{\_\_xdata (mcs51, ds390 storage class)}
9293 ) which should not be confused with the internal, directly addressable RAM
9299 \begin_inset LatexCommand \index{data (mcs51, ds390 storage class)}
9304 \begin_inset LatexCommand \index{\_\_data (mcs51, ds390 storage class)}
9309 Sometimes this built in
9313 memory has to be activated before using it (you can probably find this
9314 information on the datasheet of the microcontroller your are using, see
9316 \begin_inset LatexCommand \ref{sub:Startup-Code}
9324 Normally SDCC will only use the first bank
9325 \begin_inset LatexCommand \index{register bank (mcs51, ds390)}
9329 of registers (register bank 0), but it is possible to specify that other
9330 banks of registers (keyword
9337 \begin_inset LatexCommand \index{using (mcs51, ds390 register bank)}
9342 \begin_inset LatexCommand \index{\_\_using (mcs51, ds390 register bank)}
9348 ) should be used in interrupt
9349 \begin_inset LatexCommand \index{interrupt}
9354 \begin_inset LatexCommand \index{\_\_interrupt}
9359 By default, the compiler will place the stack after the last byte of allocated
9360 memory for variables.
9361 For example, if the first 2 banks of registers are used, and only four
9366 variables, it will position the base of the internal stack at address 20
9368 This implies that as the stack
9369 \begin_inset LatexCommand \index{stack}
9373 grows, it will use up the remaining register banks, and the 16 bytes used
9374 by the 128 bit variables, and 80 bytes for general purpose use.
9375 If any bit variables are used, the data variables will be placed in unused
9376 register banks and after the byte holding the last bit variable.
9377 For example, if register banks 0 and 1 are used, and there are 9 bit variables
9382 variables will be placed starting from address 0x10 to 0x20 and continue
9395 \begin_inset LatexCommand \index{-\/-data-loc <Value>}
9399 to specify the start address of the
9414 \begin_inset LatexCommand \index{-\/-iram-size <Value>}
9418 to specify the size of the total internal RAM (
9430 By default the 8051 linker will place the stack after the last byte of (i)data
9443 \begin_inset LatexCommand \index{-\/-stack-loc <Value>}
9447 allows you to specify the start of the stack, i.e.
9448 you could start it after any data in the general purpose area.
9449 If your microcontroller has additional indirectly addressable internal
9454 ) you can place the stack on it.
9455 You may also need to use -
9466 \begin_inset LatexCommand \index{-\/-xdata-loc<Value>}
9470 to set the start address of the external RAM (
9485 \begin_inset LatexCommand \index{-\/-xram-size <Value>}
9489 to specify its size.
9490 Same goes for the code memory, using -
9501 \begin_inset LatexCommand \index{-\/-code-loc <Value>}
9516 \begin_inset LatexCommand \index{-\/-code-size <Value>}
9521 If in doubt, don't specify any options and see if the resulting memory
9522 layout is appropriate, then you can adjust it.
9525 The linker generates two files with memory allocation information.
9526 The first, with extension .map
9527 \begin_inset LatexCommand \index{<file>.map}
9531 shows all the variables and segments.
9532 The second with extension .mem
9533 \begin_inset LatexCommand \index{<file>.mem}
9537 shows the final memory layout.
9538 The linker will complain either if memory segments overlap, there is not
9539 enough memory, or there is not enough space for stack.
9540 If you get any linking warnings and/or errors related to stack or segments
9541 allocation, take a look at either the .map or .mem files to find out what
9543 The .mem file may even suggest a solution to the problem.
9546 Z80/Z180 Storage Class
9547 \begin_inset LatexCommand \index{Storage class}
9552 \layout Subsubsection
9555 \begin_inset LatexCommand \index{sfr}
9560 \begin_inset LatexCommand \index{\_\_sfr}
9564 (in/out to 8-bit addresses)
9568 \begin_inset LatexCommand \index{Z80}
9572 family has separate address spaces for memory and
9582 \begin_inset LatexCommand \index{I/O memory (Z80, Z180)}
9586 is accessed with special instructions, e.g.:
9591 sfr at 0x78 IoPort;\SpecialChar ~
9593 /* define a var in I/O space at 78h called IoPort */
9597 Writing 0x01 to this variable generates the assembly code:
9617 \layout Subsubsection
9620 \begin_inset LatexCommand \index{sfr}
9625 \begin_inset LatexCommand \index{\_\_sfr}
9629 (in/out to 16-bit addresses)
9636 is used to support 16 bit addresses in I/O memory e.g.:
9642 \begin_inset LatexCommand \index{at}
9647 \begin_inset LatexCommand \index{\_\_at}
9654 Writing 0x01 to this variable generates the assembly code:
9659 01 23 01\SpecialChar ~
9679 \layout Subsubsection
9682 \begin_inset LatexCommand \index{sfr}
9687 \begin_inset LatexCommand \index{\_\_sfr}
9691 (in0/out0 to 8 bit addresses on Z180
9692 \begin_inset LatexCommand \index{Z180}
9697 \begin_inset LatexCommand \index{HD64180}
9704 The compiler option -
9714 -portmode=180 (80) and a compiler #pragma\SpecialChar ~
9716 \begin_inset LatexCommand \index{\#pragma portmode}
9720 =z180 (z80) is used to turn on (off) the Z180/HD64180 port addressing instructio
9730 If you include the file z180.h this will be set automatically.
9734 \begin_inset LatexCommand \index{Storage class}
9739 \layout Subsubsection
9742 \begin_inset LatexCommand \index{data (hc08 storage class)}
9747 \begin_inset LatexCommand \index{\_\_data (hc08 storage class)}
9754 The data storage class declares a variable that resides in the first 256
9755 bytes of memory (the direct page).
9756 The HC08 is most efficient at accessing variables (especially pointers)
9758 \layout Subsubsection
9761 \begin_inset LatexCommand \index{xdata (hc08 storage class)}
9766 \begin_inset LatexCommand \index{\_\_xdata (hc08 storage class)}
9773 The xdata storage class declares a variable that can reside anywhere in
9775 This is the default if no storage class is specified.
9780 \begin_inset LatexCommand \index{Absolute addressing}
9787 Data items can be assigned an absolute address with the
9790 \begin_inset LatexCommand \index{at}
9795 \begin_inset LatexCommand \index{\_\_at}
9801 keyword, in addition to a storage class, e.g.:
9807 \begin_inset LatexCommand \index{xdata (mcs51, ds390 storage class)}
9812 \begin_inset LatexCommand \index{\_\_xdata (mcs51, ds390 storage class)}
9817 \begin_inset LatexCommand \index{at}
9822 \begin_inset LatexCommand \index{\_\_at}
9826 0x7ffe unsigned int chksum;
9829 In the above example the variable chksum will be located at 0x7ffe and 0x7fff
9830 of the external ram.
9835 reserve any space for variables declared in this way (they are implemented
9836 with an equate in the assembler).
9837 Thus it is left to the programmer to make sure there are no overlaps with
9838 other variables that are declared without the absolute address.
9839 The assembler listing file (.lst
9840 \begin_inset LatexCommand \index{<file>.lst}
9844 ) and the linker output files (.rst
9845 \begin_inset LatexCommand \index{<file>.rst}
9850 \begin_inset LatexCommand \index{<file>.map}
9854 ) are good places to look for such overlaps.
9855 Variables with an absolute address are
9860 \begin_inset LatexCommand \index{Variable initialization}
9867 In case of memory mapped I/O devices the keyword
9871 has to be used to tell the compiler that accesses might not be removed:
9877 \begin_inset LatexCommand \index{volatile}
9882 \begin_inset LatexCommand \index{xdata (mcs51, ds390 storage class)}
9887 \begin_inset LatexCommand \index{at}
9891 0x8000 unsigned char PORTA_8255;
9894 For some architectures (mcs51) array accesses are more efficient if an (xdata/fa
9899 \begin_inset LatexCommand \index{Aligned array}
9906 starts at a block (256 byte) boundary
9907 \begin_inset LatexCommand \index{block boundary}
9912 \begin_inset LatexCommand \ref{sub:A-Step-by Assembler Introduction}
9918 Absolute addresses can be specified for variables in all storage classes,
9925 \begin_inset LatexCommand \index{bit}
9930 \begin_inset LatexCommand \index{at}
9937 The above example will allocate the variable at offset 0x02 in the bit-addressab
9939 There is no real advantage to assigning absolute addresses to variables
9940 in this manner, unless you want strict control over all the variables allocated.
9941 One possible use would be to write hardware portable code.
9942 For example, if you have a routine that uses one or more of the microcontroller
9943 I/O pins, and such pins are different for two different hardwares, you
9944 can declare the I/O pins in your routine using:
9950 \begin_inset LatexCommand \index{volatile}
9954 bit MOSI;\SpecialChar ~
9958 /* master out, slave in */
9960 extern volatile bit MISO;\SpecialChar ~
9964 /* master in, slave out */
9966 extern volatile bit MCLK;\SpecialChar ~
9974 /* Input and Output of a byte on a 3-wire serial bus.
9979 If needed adapt polarity of clock, polarity of data and bit order
9984 unsigned char spi_io(unsigned char out_byte)
10008 MOSI = out_byte & 0x80;
10038 /* _asm nop _endasm; */\SpecialChar ~
10046 /* for slow peripherals */
10097 Then, someplace in the code for the first hardware you would use
10103 \begin_inset LatexCommand \index{at}
10108 \begin_inset LatexCommand \index{\_\_at}
10112 0x80 MOSI;\SpecialChar ~
10116 /* I/O port 0, bit 0 */
10118 bit at 0x81 MISO;\SpecialChar ~
10122 /* I/O port 0, bit 1 */
10124 bit at 0x82 MCLK;\SpecialChar ~
10128 /* I/O port 0, bit 2 */
10131 Similarly, for the second hardware you would use
10136 bit at 0x83 MOSI;\SpecialChar ~
10140 /* I/O port 0, bit 3 */
10142 bit at 0x91 MISO;\SpecialChar ~
10146 /* I/O port 1, bit 1 */
10149 \begin_inset LatexCommand \index{bit}
10153 at 0x92 MCLK;\SpecialChar ~
10157 /* I/O port 1, bit 2 */
10160 and you can use the same hardware dependent routine without changes, as
10161 for example in a library.
10162 This is somehow similar to sbit, but only one absolute address has to be
10163 specified in the whole project.
10167 \begin_inset LatexCommand \index{Parameters}
10172 \begin_inset LatexCommand \index{function parameter}
10177 \begin_inset LatexCommand \index{local variables}
10182 \begin_inset LatexCommand \label{sec:Parameters-and-Local-Variables}
10189 Automatic (local) variables and parameters to functions can either be placed
10190 on the stack or in data-space.
10191 The default action of the compiler is to place these variables in the internal
10192 RAM (for small model) or external RAM (for large model).
10193 This in fact makes them similar to
10196 \begin_inset LatexCommand \index{static}
10202 so by default functions are non-reentrant
10203 \begin_inset LatexCommand \index{reentrant}
10212 They can be placed on the stack
10213 \begin_inset LatexCommand \index{stack}
10230 \begin_inset LatexCommand \index{-\/-stack-auto}
10238 #pragma\SpecialChar ~
10242 \begin_inset LatexCommand \index{\#pragma stackauto}
10249 \begin_inset LatexCommand \index{reentrant}
10255 keyword in the function declaration, e.g.:
10260 unsigned char foo(char i) reentrant
10274 Since stack space on 8051 is limited, the
10292 option should be used sparingly.
10293 Note that the reentrant keyword just means that the parameters & local
10294 variables will be allocated to the stack, it
10298 mean that the function is register bank
10299 \begin_inset LatexCommand \index{register bank (mcs51, ds390)}
10308 \begin_inset LatexCommand \index{local variables}
10312 can be assigned storage classes and absolute
10313 \begin_inset LatexCommand \index{Absolute addressing}
10322 unsigned char foo()
10330 xdata unsigned char i;
10343 \begin_inset LatexCommand \index{at}
10347 0x31 unsigned char j;
10359 In the above example the variable
10363 will be allocated in the external ram,
10367 in bit addressable space and
10386 or when a function is declared as
10390 this should only be done for static variables.
10394 \begin_inset LatexCommand \index{function parameter}
10398 however are not allowed any storage class
10399 \begin_inset LatexCommand \index{Storage class}
10403 , (storage classes for parameters will be ignored), their allocation is
10404 governed by the memory model in use, and the reentrancy options.
10407 It is however allowed to use bit parameters in reentrant functions and also
10408 non-static local bit variables are supported.
10409 Efficient use is limited to 8 semi-bitregisters in bit space.
10410 They are pushed and popped to stack as a single byte just like the normal
10415 \begin_inset LatexCommand \label{sub:Overlaying}
10420 \begin_inset LatexCommand \index{Overlaying}
10428 \begin_inset LatexCommand \index{reentrant}
10432 functions SDCC will try to reduce internal ram space usage by overlaying
10433 parameters and local variables of a function (if possible).
10434 Parameters and local variables
10435 \begin_inset LatexCommand \index{local variables}
10439 of a function will be allocated to an overlayable segment if the function
10442 no other function calls and the function is non-reentrant and the memory
10444 \begin_inset LatexCommand \index{Memory model}
10451 If an explicit storage class
10452 \begin_inset LatexCommand \index{Storage class}
10456 is specified for a local variable, it will NOT be overlayed.
10459 Note that the compiler (not the linkage editor) makes the decision for overlayin
10461 Functions that are called from an interrupt service routine should be preceded
10462 by a #pragma\SpecialChar ~
10464 \begin_inset LatexCommand \index{\#pragma nooverlay}
10468 if they are not reentrant.
10471 Also note that the compiler does not do any processing of inline assembler
10472 code, so the compiler might incorrectly assign local variables and parameters
10473 of a function into the overlay segment if the inline assembler code calls
10474 other c-functions that might use the overlay.
10475 In that case the #pragma\SpecialChar ~
10476 nooverlay should be used.
10479 Parameters and local variables of functions that contain 16 or 32 bit multiplica
10481 \begin_inset LatexCommand \index{Multiplication}
10486 \begin_inset LatexCommand \index{Division}
10490 will NOT be overlayed since these are implemented using external functions,
10499 \begin_inset LatexCommand \index{\#pragma nooverlay}
10505 void set_error(unsigned char errcd)
10521 void some_isr () interrupt
10522 \begin_inset LatexCommand \index{interrupt}
10552 In the above example the parameter
10560 would be assigned to the overlayable segment if the #pragma\SpecialChar ~
10562 not present, this could cause unpredictable runtime behavior when called
10563 from an interrupt service routine.
10564 The #pragma\SpecialChar ~
10565 nooverlay ensures that the parameters and local variables for
10566 the function are NOT overlayed.
10569 Interrupt Service Routines
10570 \begin_inset LatexCommand \label{sub:Interrupt-Service-Routines}
10577 General Information
10592 outines to be coded in C, with some extended keywords.
10597 void timer_isr (void) interrupt 1 using 1
10611 The optional number following the
10614 \begin_inset LatexCommand \index{interrupt}
10619 \begin_inset LatexCommand \index{\_\_interrupt}
10625 keyword is the interrupt number this routine will service.
10626 When present, the compiler will insert a call to this routine in the interrupt
10627 vector table for the interrupt number specified.
10628 If you have multiple source files in your project, interrupt service routines
10629 can be present in any of them, but a prototype of the isr MUST be present
10630 or included in the file that contains the function
10638 \begin_inset LatexCommand \index{using (mcs51, ds390 register bank)}
10643 \begin_inset LatexCommand \index{\_\_using (mcs51, ds390 register bank)}
10649 keyword can be used to tell the compiler to use the specified register
10650 bank (8051 specific) when generating code for this function.
10656 Interrupt service routines open the door for some very interesting bugs:
10658 If an interrupt service routine changes variables which are accessed by
10659 other functions these variables have to be declared
10664 \begin_inset LatexCommand \index{volatile}
10672 If the access to these variables is not
10675 \begin_inset LatexCommand \index{atomic}
10682 the processor needs more than one instruction for the access and could
10683 be interrupted while accessing the variable) the interrupt must be disabled
10684 during the access to avoid inconsistent data.
10685 Access to 16 or 32 bit variables is obviously not atomic on 8 bit CPUs
10686 and should be protected by disabling interrupts.
10687 You're not automatically on the safe side if you use 8 bit variables though.
10688 We need an example here: f.e.
10689 on the 8051 the harmless looking
10690 \begin_inset Quotes srd
10695 flags\SpecialChar ~
10700 \begin_inset Quotes sld
10709 \begin_inset Quotes srd
10714 flags\SpecialChar ~
10719 \begin_inset Quotes sld
10722 from within an interrupt routine might get lost if the interrupt occurs
10725 \begin_inset Quotes sld
10730 counter\SpecialChar ~
10735 \begin_inset Quotes srd
10738 is not atomic on the 8051 even if
10742 is located in data memory.
10743 Bugs like these are hard to reproduce and can cause a lot of trouble.
10747 The return address and the registers used in the interrupt service routine
10748 are saved on the stack
10749 \begin_inset LatexCommand \index{stack}
10753 so there must be sufficient stack space.
10754 If there isn't variables or registers (or even the return address itself)
10761 \begin_inset LatexCommand \index{stack overflow}
10765 is most likely to happen if the interrupt occurs during the
10766 \begin_inset Quotes sld
10770 \begin_inset Quotes srd
10773 subroutine when the stack is already in use for f.e.
10774 many return addresses.
10777 A special note here, int (16 bit) and long (32 bit) integer division
10778 \begin_inset LatexCommand \index{Division}
10783 \begin_inset LatexCommand \index{Multiplication}
10788 \begin_inset LatexCommand \index{Modulus}
10793 \begin_inset LatexCommand \index{Floating point support}
10797 operations are implemented using external support routines developed in
10799 If an interrupt service routine needs to do any of these operations then
10800 the support routines (as mentioned in a following section) will have to
10801 be recompiled using the
10814 \begin_inset LatexCommand \index{-\/-stack-auto}
10820 option and the source file will need to be compiled using the
10835 \begin_inset LatexCommand \index{-\/-int-long-reent}
10842 Calling other functions from an interrupt service routine is not recommended,
10843 avoid it if possible.
10844 Note that when some function is called from an interrupt service routine
10845 it should be preceded by a #pragma\SpecialChar ~
10847 \begin_inset LatexCommand \index{\#pragma nooverlay}
10851 if it is not reentrant.
10852 Furthermore nonreentrant functions should not be called from the main program
10853 while the interrupt service routine might be active.
10859 \begin_inset LatexCommand \ref{sub:Overlaying}
10864 about Overlaying and section
10865 \begin_inset LatexCommand \ref{sub:Functions-using-private-banks}
10870 about Functions using private register banks.
10873 MCS51/DS390 Interrupt Service Routines
10876 Interrupt numbers and the corresponding address & descriptions for the Standard
10877 8051/8052 are listed below.
10878 SDCC will automatically adjust the interrupt vector table to the maximum
10879 interrupt number specified.
10885 \begin_inset Tabular
10886 <lyxtabular version="3" rows="7" columns="3">
10888 <column alignment="center" valignment="top" leftline="true" width="0in">
10889 <column alignment="center" valignment="top" leftline="true" width="0in">
10890 <column alignment="center" valignment="top" leftline="true" rightline="true" width="0in">
10891 <row topline="true" bottomline="true">
10892 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
10900 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
10908 <cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
10917 <row topline="true">
10918 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
10926 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
10934 <cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
10943 <row topline="true">
10944 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
10952 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
10960 <cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
10969 <row topline="true">
10970 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
10978 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
10986 <cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
10995 <row topline="true">
10996 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
11004 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
11012 <cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
11021 <row topline="true">
11022 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
11030 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
11038 <cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
11047 <row topline="true" bottomline="true">
11048 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
11056 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
11064 <cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
11082 If the interrupt service routine is defined without
11085 \begin_inset LatexCommand \index{using (mcs51, ds390 register bank)}
11090 \begin_inset LatexCommand \index{\_\_using (mcs51, ds390 register bank)}
11096 a register bank or with register bank 0 (
11100 0), the compiler will save the registers used by itself on the stack upon
11101 entry and restore them at exit, however if such an interrupt service routine
11102 calls another function then the entire register bank will be saved on the
11104 This scheme may be advantageous for small interrupt service routines which
11105 have low register usage.
11108 If the interrupt service routine is defined to be using a specific register
11113 & psw are saved and restored, if such an interrupt service routine calls
11114 another function (using another register bank) then the entire register
11115 bank of the called function will be saved on the stack.
11116 This scheme is recommended for larger interrupt service routines.
11119 HC08 Interrupt Service Routines
11122 Since the number of interrupts available is chip specific and the interrupt
11123 vector table always ends at the last byte of memory, the interrupt numbers
11124 corresponds to the interrupt vectors in reverse order of address.
11125 For example, interrupt 1 will use the interrupt vector at 0xfffc, interrupt
11126 2 will use the interrupt vector at 0xfffa, and so on.
11127 However, interrupt 0 (the reset vector at 0xfffe) is not redefinable in
11128 this way; instead see section
11129 \begin_inset LatexCommand \ref{sub:Startup-Code}
11133 for details on customizing startup.
11136 Z80 Interrupt Service Routines
11139 The Z80 uses several different methods for determining the correct interrupt
11140 vector depending on the hardware implementation.
11141 Therefore, SDCC ignores the optional interrupt number and does not attempt
11142 to generate an interrupt vector table.
11145 By default, SDCC generates code for a maskable interrupt, which uses an
11146 RETI instruction to return from the interrupt.
11147 To write an interrupt handler for the non-maskable interrupt, which needs
11148 an RETN instruction instead, add the
11157 void nmi_isr (void) critical interrupt
11171 Enabling and Disabling Interrupts
11174 Critical Functions and Critical Statements
11177 A special keyword may be associated with a block or a function declaring
11183 SDCC will generate code to disable all interrupts
11184 \begin_inset LatexCommand \index{interrupt}
11188 upon entry to a critical function and restore the interrupt enable to the
11189 previous state before returning.
11190 Nesting critical functions will need one additional byte on the stack
11191 \begin_inset LatexCommand \index{stack}
11200 int foo () critical
11201 \begin_inset LatexCommand \index{critical}
11206 \begin_inset LatexCommand \index{\_\_critical}
11231 The critical attribute maybe used with other attributes like
11241 may also be used to disable interrupts more locally:
11249 More than one statement could have been included in the block.
11252 Enabling and Disabling Interrupts directly
11256 \begin_inset LatexCommand \index{interrupt}
11260 can also be disabled and enabled directly (8051):
11265 EA = 0;\SpecialChar ~
11328 EA = 1;\SpecialChar ~
11395 On other architectures which have seperate opcodes for enabling and disabling
11396 interrupts you might want to make use of defines with inline assembly
11397 \begin_inset LatexCommand \index{Assembler routines}
11407 \begin_inset LatexCommand \index{\_asm}
11416 \begin_inset LatexCommand \index{\_endasm}
11425 #define SEI _asm\SpecialChar ~
11437 Note: it is sometimes sufficient to disable only a specific interrupt source
11439 a timer or serial interrupt by manipulating an
11442 \begin_inset LatexCommand \index{interrupt mask}
11452 Usually the time during which interrupts are disabled should be kept as
11454 This minimizes both
11459 \begin_inset LatexCommand \index{interrupt latency}
11463 (the time between the occurrence of the interrupt and the execution of
11464 the first code in the interrupt routine) and
11469 \begin_inset LatexCommand \index{interrupt jitter}
11473 (the difference between the shortest and the longest interrupt latency).
11474 These really are something different, f.e.
11475 a serial interrupt has to be served before its buffer overruns so it cares
11476 for the maximum interrupt latency, whereas it does not care about jitter.
11477 On a loudspeaker driven via a digital to analog converter which is fed
11478 by an interrupt a latency of a few milliseconds might be tolerable, whereas
11479 a much smaller jitter will be very audible.
11482 You can reenable interrupts within an interrupt routine and on some architecture
11483 s you can make use of two (or more) levels of
11485 interrupt priorities
11488 \begin_inset LatexCommand \index{interrupt priority}
11493 On some architectures which don't support interrupt priorities these can
11494 be implemented by manipulating the interrupt mask and reenabling interrupts
11495 within the interrupt routine.
11496 Check there is sufficient space on the stack
11497 \begin_inset LatexCommand \index{stack}
11501 and don't add complexity unless you have to.
11506 \begin_inset LatexCommand \index{semaphore}
11510 locking (mcs51/ds390)
11513 Some architectures (mcs51/ds390) have an atomic
11514 \begin_inset LatexCommand \index{atomic}
11527 These type of instructions are typically used in preemptive multitasking
11528 systems, where a routine f.e.
11529 claims the use of a data structure ('acquires a lock
11530 \begin_inset LatexCommand \index{lock}
11534 on it'), makes some modifications and then releases the lock when the data
11535 structure is consistent again.
11536 The instruction may also be used if interrupt and non-interrupt code have
11537 to compete for a resource.
11538 With the atomic bit test and clear instruction interrupts
11539 \begin_inset LatexCommand \index{interrupt}
11543 don't have to be disabled for the locking operation.
11547 SDCC generates this instruction if the source follows this pattern:
11553 \begin_inset LatexCommand \index{volatile}
11557 bit resource_is_free;
11561 if (resource_is_free)
11571 resource_is_free=0;
11584 resource_is_free=1;
11591 Note, mcs51 and ds390 support only an atomic
11592 \begin_inset LatexCommand \index{atomic}
11600 instruction (as opposed to atomic bit test and
11605 Functions using private register banks
11606 \begin_inset LatexCommand \label{sub:Functions-using-private-banks}
11613 Some architectures have support for quickly changing register sets.
11614 SDCC supports this feature with the
11617 \begin_inset LatexCommand \index{using (mcs51, ds390 register bank)}
11622 \begin_inset LatexCommand \index{\_\_using (mcs51, ds390 register bank)}
11628 attribute (which tells the compiler to use a register bank
11629 \begin_inset LatexCommand \index{register bank (mcs51, ds390)}
11633 other than the default bank zero).
11634 It should only be applied to
11637 \begin_inset LatexCommand \index{interrupt}
11643 functions (see footnote below).
11644 This will in most circumstances make the generated ISR code more efficient
11645 since it will not have to save registers on the stack.
11652 attribute will have no effect on the generated code for a
11656 function (but may occasionally be useful anyway
11662 possible exception: if a function is called ONLY from 'interrupt' functions
11663 using a particular bank, it can be declared with the same 'using' attribute
11664 as the calling 'interrupt' functions.
11665 For instance, if you have several ISRs using bank one, and all of them
11666 call memcpy(), it might make sense to create a specialized version of memcpy()
11667 'using 1', since this would prevent the ISR from having to save bank zero
11668 to the stack on entry and switch to bank zero before calling the function
11675 (pending: I don't think this has been done yet)
11682 function using a non-zero bank will assume that it can trash that register
11683 bank, and will not save it.
11684 Since high-priority interrupts
11685 \begin_inset LatexCommand \index{interrupts}
11690 \begin_inset LatexCommand \index{interrupt priority}
11694 can interrupt low-priority ones on the 8051 and friends, this means that
11695 if a high-priority ISR
11699 a particular bank occurs while processing a low-priority ISR
11703 the same bank, terrible and bad things can happen.
11704 To prevent this, no single register bank should be
11708 by both a high priority and a low priority ISR.
11709 This is probably most easily done by having all high priority ISRs use
11710 one bank and all low priority ISRs use another.
11711 If you have an ISR which can change priority at runtime, you're on your
11712 own: I suggest using the default bank zero and taking the small performance
11716 It is most efficient if your ISR calls no other functions.
11717 If your ISR must call other functions, it is most efficient if those functions
11718 use the same bank as the ISR (see note 1 below); the next best is if the
11719 called functions use bank zero.
11720 It is very inefficient to call a function using a different, non-zero bank
11726 \begin_inset LatexCommand \label{sub:Startup-Code}
11731 \begin_inset LatexCommand \index{Startup code}
11738 MCS51/DS390 Startup Code
11741 The compiler inserts a call to the C routine
11743 _sdcc_external_startup()
11744 \begin_inset LatexCommand \index{\_sdcc\_external\_startup()}
11753 at the start of the CODE area.
11754 This routine is in the runtime library
11755 \begin_inset LatexCommand \index{Runtime library}
11760 By default this routine returns 0, if this routine returns a non-zero value,
11761 the static & global variable initialization will be skipped and the function
11762 main will be invoked.
11763 Otherwise static & global variables will be initialized before the function
11767 _sdcc_external_startup()
11769 routine to your program to override the default if you need to setup hardware
11770 or perform some other critical operation prior to static & global variable
11772 \begin_inset LatexCommand \index{Variable initialization}
11777 On some mcs51 variants xdata
11778 \begin_inset LatexCommand \index{xdata (mcs51, ds390 storage class)}
11782 memory has to be explicitly enabled before it can be accessed or if the
11783 watchdog needs to be disabled, this is the place to do it.
11784 The startup code clears all internal data memory, 256 bytes by default,
11785 but from 0 to n-1 if
11798 \begin_inset LatexCommand \index{-\/-iram-size <Value>}
11805 (recommended for Chipcon CC1010).
11808 See also the compiler option
11827 \begin_inset LatexCommand \index{-\/-no-xinit-opt}
11832 \begin_inset LatexCommand \ref{sub:MCS51-variants}
11837 about MCS51-variants.
11843 The HC08 startup code follows the same scheme as the MCS51 startup code.
11849 On the Z80 the startup code is inserted by linking with crt0.o which is generated
11850 from sdcc/device/lib/z80/crt0.s.
11851 If you need a different startup code you can use the compiler option
11872 \begin_inset LatexCommand \index{-\/-no-std-crt0}
11876 and provide your own crt0.o.
11880 Inline Assembler Code
11881 \begin_inset LatexCommand \index{Assembler routines}
11888 A Step by Step Introduction
11889 \begin_inset LatexCommand \label{sub:A-Step-by Assembler Introduction}
11896 Starting from a small snippet of c-code this example shows for the MCS51
11897 how to use inline assembly, access variables, a function parameter and
11898 an array in xdata memory.
11899 The example uses an MCS51 here but is easily adapted for other architectures.
11900 This is a buffer routine which should be optimized:
11907 \begin_inset LatexCommand \index{far (storage class)}
11912 \begin_inset LatexCommand \index{\_\_far (storage class)}
11917 \begin_inset LatexCommand \index{at}
11922 \begin_inset LatexCommand \index{\_\_at}
11927 \begin_inset LatexCommand \index{Aligned array}
11933 unsigned char head,tail;
11937 void to_buffer( unsigned char c )
11945 if( head != tail-1 )
11955 buf[ head++ ] = c;\SpecialChar ~
11959 /* access to a 256 byte aligned array */
11964 If the code snippet (assume it is saved in buffer.c) is compiled with SDCC
11965 then a corresponding buffer.asm file is generated.
11966 We define a new function
11970 in file buffer.c in which we cut and paste the generated code, removing
11971 unwanted comments and some ':'.
11973 \begin_inset Quotes sld
11977 \begin_inset Quotes srd
11981 \begin_inset Quotes sld
11985 \begin_inset Quotes srd
11988 to the beginning and the end of the function body:
11994 /* With a cut and paste from the .asm file, we have something to start with.
11999 The function is not yet OK! (registers aren't saved) */
12001 void to_buffer_asm( unsigned char c )
12010 \begin_inset LatexCommand \index{\_asm}
12015 \begin_inset LatexCommand \index{\_\_asm}
12029 ;buffer.c if( head != tail-1 )
12077 ;buffer.c buf[ head++ ] = c; /* access to a 256 byte aligned array */
12078 \begin_inset LatexCommand \index{Aligned array}
12143 \begin_inset LatexCommand \index{\_endasm}
12148 \begin_inset LatexCommand \index{\_\_endasm}
12157 The new file buffer.c should compile with only one warning about the unreferenced
12158 function argument 'c'.
12159 Now we hand-optimize the assembly code and insert an #define USE_ASSEMBLY
12160 (1) and finally have:
12166 unsigned char far at 0x7f00 buf[0x100];
12168 unsigned char head,tail;
12170 #define USE_ASSEMBLY (1)
12178 void to_buffer( unsigned char c )
12186 if( head != tail-1 )
12206 void to_buffer( unsigned char c )
12214 c; // to avoid warning: unreferenced function argument
12221 \begin_inset LatexCommand \index{\_asm}
12226 \begin_inset LatexCommand \index{\_\_asm}
12240 ; save used registers here.
12251 ; If we were still using r2,r3 we would have to push them here.
12254 ; if( head != tail-1 )
12297 ; we could do an ANL a,#0x0f here to use a smaller buffer (see below)
12321 ; buf[ head++ ] = c;
12332 a,dpl \SpecialChar ~
12339 ; dpl holds lower byte of function argument
12350 dpl,_head \SpecialChar ~
12353 ; buf is 0x100 byte aligned so head can be used directly
12395 ; we could do an ANL _head,#0x0f here to use a smaller buffer (see above)
12407 ; restore used registers here
12414 \begin_inset LatexCommand \index{\_endasm}
12419 \begin_inset LatexCommand \index{\_\_endasm}
12430 The inline assembler code can contain any valid code understood by the assembler
12431 , this includes any assembler directives and comment lines
12437 The assembler does not like some characters like ':' or ''' in comments.
12438 You'll find an 100+ pages assembler manual in sdcc/as/doc/asxhtm.html
12439 \begin_inset LatexCommand \index{asXXXX (as-gbz80, as-hc08, asx8051, as-z80)}
12444 \begin_inset LatexCommand \index{Assembler documentation}
12452 The compiler does not do any validation of the code within the
12455 \begin_inset LatexCommand \index{\_asm}
12460 \begin_inset LatexCommand \index{\_\_asm}
12468 \begin_inset LatexCommand \index{\_endasm}
12473 \begin_inset LatexCommand \index{\_\_endasm}
12482 Specifically it will not know which registers are used and thus register
12484 \begin_inset LatexCommand \index{push/pop}
12488 has to be done manually.
12492 It is recommended that each assembly instruction (including labels) be placed
12493 in a separate line (as the example shows).
12507 \begin_inset LatexCommand \index{-\/-peep-asm}
12513 command line option is used, the inline assembler code will be passed through
12514 the peephole optimizer
12515 \begin_inset LatexCommand \index{Peephole optimizer}
12520 There are only a few (if any) cases where this option makes sense, it might
12521 cause some unexpected changes in the inline assembler code.
12522 Please go through the peephole optimizer rules defined in file
12526 before using this option.
12530 \begin_inset LatexCommand \label{sub:Naked-Functions}
12535 \begin_inset LatexCommand \index{Naked functions}
12542 A special keyword may be associated with a function declaring it as
12545 \begin_inset LatexCommand \index{\_naked}
12550 \begin_inset LatexCommand \index{\_\_naked}
12561 function modifier attribute prevents the compiler from generating prologue
12562 \begin_inset LatexCommand \index{function prologue}
12567 \begin_inset LatexCommand \index{function epilogue}
12571 code for that function.
12572 This means that the user is entirely responsible for such things as saving
12573 any registers that may need to be preserved, selecting the proper register
12574 bank, generating the
12578 instruction at the end, etc.
12579 Practically, this means that the contents of the function must be written
12580 in inline assembler.
12581 This is particularly useful for interrupt functions, which can have a large
12582 (and often unnecessary) prologue/epilogue.
12583 For example, compare the code generated by these two functions:
12589 \begin_inset LatexCommand \index{volatile}
12593 data unsigned char counter;
12597 void simpleInterrupt(void) interrupt
12598 \begin_inset LatexCommand \index{interrupt}
12603 \begin_inset LatexCommand \index{\_\_interrupt}
12621 void nakedInterrupt(void) interrupt 2 _naked
12630 \begin_inset LatexCommand \index{\_asm}
12635 \begin_inset LatexCommand \index{\_\_asm}
12652 _counter ; does not change flags, no need to save psw
12664 ; MUST explicitly include ret or reti in _naked function.
12671 \begin_inset LatexCommand \index{\_endasm}
12676 \begin_inset LatexCommand \index{\_\_endasm}
12685 For an 8051 target, the generated simpleInterrupt looks like:
12826 whereas nakedInterrupt looks like:
12841 _counter ; does not change flags, no need to save psw
12859 ; MUST explicitly include ret or reti in _naked function
12862 The related directive #pragma exclude
12863 \begin_inset LatexCommand \index{\#pragma exclude}
12867 allows a more fine grained control over pushing & popping
12868 \begin_inset LatexCommand \index{push/pop}
12875 While there is nothing preventing you from writing C code inside a
12879 function, there are many ways to shoot yourself in the foot doing this,
12880 and it is recommended that you stick to inline assembler.
12883 Use of Labels within Inline Assembler
12886 SDCC allows the use of in-line assembler with a few restrictions regarding
12888 In older versions of the compiler all labels defined within inline assembler
12897 where nnnn is a number less than 100 (which implies a limit of utmost 100
12898 inline assembler labels
12912 \begin_inset LatexCommand \index{\_asm}
12917 \begin_inset LatexCommand \index{\_\_asm}
12947 \begin_inset LatexCommand \index{\_endasm}
12952 \begin_inset LatexCommand \index{\_\_endasm}
12959 Inline assembler code cannot reference any C-Labels, however it can reference
12961 \begin_inset LatexCommand \index{Labels}
12965 defined by the inline assembler, e.g.:
12990 ; some assembler code
13010 /* some more c code */
13012 clabel:\SpecialChar ~
13014 /* inline assembler cannot reference this label */
13026 $0003: ;label (can be referenced by inline assembler only)
13033 \begin_inset LatexCommand \index{\_endasm}
13038 \begin_inset LatexCommand \index{\_\_endasm}
13048 /* some more c code */
13053 In other words inline assembly code can access labels defined in inline
13054 assembly within the scope of the function.
13055 The same goes the other way, i.e.
13056 labels defines in inline assembly can not be accessed by C statements.
13059 Interfacing with Assembler Code
13060 \begin_inset LatexCommand \index{Assembler routines}
13067 Global Registers used for Parameter Passing
13068 \begin_inset LatexCommand \index{Parameter passing}
13075 The compiler always uses the global registers
13078 \begin_inset LatexCommand \index{DPTR, DPH, DPL}
13083 \begin_inset LatexCommand \index{DPTR}
13088 \begin_inset LatexCommand \index{B (mcs51, ds390 register)}
13097 \begin_inset LatexCommand \index{ACC (mcs51, ds390 register)}
13103 to pass the first parameter to a routine.
13104 The second parameter onwards is either allocated on the stack (for reentrant
13115 -stack-auto is used) or in data / xdata memory (depending on the memory
13120 Assembler Routine (non-reentrant)
13123 In the following example
13124 \begin_inset LatexCommand \index{reentrant}
13129 \begin_inset LatexCommand \index{Assembler routines (non-reentrant)}
13133 the function c_func calls an assembler routine asm_func, which takes two
13135 \begin_inset LatexCommand \index{function parameter}
13144 extern int asm_func(unsigned char, unsigned char);
13148 int c_func (unsigned char i, unsigned char j)
13156 return asm_func(i,j);
13170 return c_func(10,9);
13175 The corresponding assembler function is:
13180 .globl _asm_func_PARM_2
13281 \begin_inset LatexCommand \index{DPTR, DPH, DPL}
13298 Note here that the return values
13299 \begin_inset LatexCommand \index{return value}
13303 are placed in 'dpl' - One byte return value, 'dpl' LSB & 'dph' MSB for
13305 'dpl', 'dph' and 'b' for three byte values (generic pointers) and 'dpl','dph','
13306 b' & 'acc' for four byte values.
13309 The parameter naming convention is _<function_name>_PARM_<n>, where n is
13310 the parameter number starting from 1, and counting from the left.
13311 The first parameter is passed in
13312 \begin_inset Quotes eld
13316 \begin_inset Quotes erd
13319 for a one byte parameter,
13320 \begin_inset Quotes eld
13324 \begin_inset Quotes erd
13328 \begin_inset Quotes eld
13332 \begin_inset Quotes erd
13335 for three bytes and
13336 \begin_inset Quotes eld
13340 \begin_inset Quotes erd
13343 for a four bytes parameter.
13344 The variable name for the second parameter will be _<function_name>_PARM_2.
13348 Assemble the assembler routine with the following command:
13355 asx8051 -losg asmfunc.asm
13362 Then compile and link the assembler routine to the C source file with the
13370 sdcc cfunc.c asmfunc.rel
13373 Assembler Routine (reentrant)
13377 \begin_inset LatexCommand \index{reentrant}
13382 \begin_inset LatexCommand \index{Assembler routines (reentrant)}
13386 the second parameter
13387 \begin_inset LatexCommand \index{function parameter}
13391 onwards will be passed on the stack, the parameters are pushed from right
13393 after the call the leftmost parameter will be on the top of the stack.
13394 Here is an example:
13399 extern int asm_func(unsigned char, unsigned char);
13403 int c_func (unsigned char i, unsigned char j) reentrant
13411 return asm_func(i,j);
13425 return c_func(10,9);
13430 The corresponding assembler routine is:
13530 The compiling and linking procedure remains the same, however note the extra
13531 entry & exit linkage required for the assembler code, _bp is the stack
13532 frame pointer and is used to compute the offset into the stack for parameters
13533 and local variables.
13537 \begin_inset LatexCommand \index{int (16 bit)}
13542 \begin_inset LatexCommand \index{long (32 bit)}
13549 For signed & unsigned int (16 bit) and long (32 bit) variables, division,
13550 multiplication and modulus operations are implemented by support routines.
13551 These support routines are all developed in ANSI-C to facilitate porting
13552 to other MCUs, although some model specific assembler optimizations are
13554 The following files contain the described routines, all of them can be
13555 found in <installdir>/share/sdcc/lib.
13561 \begin_inset Tabular
13562 <lyxtabular version="3" rows="11" columns="2">
13564 <column alignment="center" valignment="top" leftline="true" width="0">
13565 <column alignment="center" valignment="top" leftline="true" rightline="true" width="0">
13566 <row topline="true" bottomline="true">
13567 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
13577 <cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
13588 <row topline="true">
13589 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
13597 <cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
13602 16 bit multiplication
13606 <row topline="true">
13607 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
13615 <cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
13620 signed 16 bit division (calls _divuint)
13624 <row topline="true">
13625 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
13633 <cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
13638 unsigned 16 bit division
13642 <row topline="true">
13643 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
13651 <cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
13656 signed 16 bit modulus (calls _moduint)
13660 <row topline="true">
13661 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
13669 <cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
13674 unsigned 16 bit modulus
13678 <row topline="true">
13679 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
13687 <cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
13692 32 bit multiplication
13696 <row topline="true">
13697 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
13705 <cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
13710 signed 32 division (calls _divulong)
13714 <row topline="true">
13715 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
13723 <cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
13728 unsigned 32 division
13732 <row topline="true">
13733 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
13741 <cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
13746 signed 32 bit modulus (calls _modulong)
13750 <row topline="true" bottomline="true">
13751 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
13759 <cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
13764 unsigned 32 bit modulus
13777 Since they are compiled as
13782 \begin_inset LatexCommand \index{reentrant}
13787 \begin_inset LatexCommand \index{interrupt}
13791 service routines should not do any of the above operations.
13792 If this is unavoidable then the above routines will need to be compiled
13806 \begin_inset LatexCommand \index{-\/-stack-auto}
13812 option, after which the source program will have to be compiled with
13825 \begin_inset LatexCommand \index{-\/-int-long-reent}
13832 Notice that you don't have to call these routines directly.
13833 The compiler will use them automatically every time an integer operation
13837 Floating Point Support
13838 \begin_inset LatexCommand \index{Floating point support}
13845 SDCC supports IEEE (single precision 4 bytes) floating point numbers.The
13846 floating point support routines are derived from gcc's floatlib.c and consist
13847 of the following routines:
13855 \begin_inset Tabular
13856 <lyxtabular version="3" rows="17" columns="2">
13858 <column alignment="center" valignment="top" leftline="true" width="0">
13859 <column alignment="center" valignment="top" leftline="true" rightline="true" width="0">
13860 <row topline="true" bottomline="true">
13861 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
13878 <cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
13887 <row topline="true">
13888 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
13905 <cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
13919 add floating point numbers
13923 <row topline="true">
13924 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
13941 <cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
13955 subtract floating point numbers
13959 <row topline="true">
13960 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
13977 <cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
13991 divide floating point numbers
13995 <row topline="true">
13996 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
14013 <cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
14027 multiply floating point numbers
14031 <row topline="true">
14032 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
14049 <cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
14063 convert floating point to unsigned char
14067 <row topline="true">
14068 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
14085 <cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
14099 convert floating point to signed char
14103 <row topline="true">
14104 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
14121 <cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
14135 convert floating point to unsigned int
14139 <row topline="true">
14140 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
14157 <cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
14171 convert floating point to signed int
14175 <row topline="true">
14176 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
14202 <cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
14216 convert floating point to unsigned long
14220 <row topline="true">
14221 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
14238 <cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
14252 convert floating point to signed long
14256 <row topline="true">
14257 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
14274 <cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
14288 convert unsigned char to floating point
14292 <row topline="true">
14293 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
14310 <cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
14324 convert char to floating point number
14328 <row topline="true">
14329 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
14346 <cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
14360 convert unsigned int to floating point
14364 <row topline="true">
14365 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
14382 <cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
14396 convert int to floating point numbers
14400 <row topline="true">
14401 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
14418 <cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
14432 convert unsigned long to floating point number
14436 <row topline="true" bottomline="true">
14437 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
14454 <cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
14468 convert long to floating point number
14481 These support routines are developed in ANSI-C so there is room for space
14482 and speed improvement
14488 The floating point routines for the mcs51 are implemented in assembler
14492 Note if all these routines are used simultaneously the data space might
14494 For serious floating point usage the large model might be needed.
14495 Also notice that you don't have to call this routines directly.
14496 The compiler will use them automatically every time a floating point operation
14501 \begin_inset LatexCommand \index{Libraries}
14510 <pending: this is messy and incomplete - a little more information is in
14511 sdcc/doc/libdoc.txt
14516 Compiler support routines (_gptrget, _mulint etc.)
14519 Stdclib functions (puts, printf, strcat etc.)
14520 \layout Subsubsection
14526 \begin_inset LatexCommand \index{<stdio.h>}
14530 As usual on embedded systems you have to provide your own
14533 \begin_inset LatexCommand \index{getchar()}
14542 \begin_inset LatexCommand \index{putchar()}
14549 SDCC does not know whether the system connects to a serial line with or
14550 without handshake, LCD, keyboard or other device.
14551 You'll find examples for serial routines f.e.
14552 in sdcc/device/lib.
14558 \begin_inset LatexCommand \index{printf()}
14568 does not support float (except on ds390).
14569 To enable this recompile it with the option
14582 \begin_inset LatexCommand \index{USE\_FLOATS}
14588 on the command line.
14602 \begin_inset LatexCommand \index{-\/-model-large}
14608 for the mcs51 port, since this uses a lot of memory.
14611 If you're short on memory you might want to use
14614 \begin_inset LatexCommand \index{printf\_small()}
14629 For the mcs51 there additionally are assembly versions
14632 \begin_inset LatexCommand \index{printf\_tiny() (mcs51)}
14641 \begin_inset LatexCommand \index{printf\_fast() (mcs51)}
14650 \begin_inset LatexCommand \index{printf\_fast\_f() (mcs51)}
14656 which should fit the requirements of many embedded systems (printf_fast()
14657 can be customized by unsetting #defines to
14661 support long variables and field widths).
14664 Math functions (sin, pow, sqrt etc.)
14671 \begin_inset LatexCommand \index{Libraries}
14675 included in SDCC should have a license at least as liberal as the GNU Lesser
14676 General Public License
14677 \begin_inset LatexCommand \index{GNU Lesser General Public License, LGPL}
14688 license statements for the libraries are missing.
14689 sdcc/device/lib/ser_ir.c
14693 come with a GPL (as opposed to LGPL) License - this will not be liberal
14694 enough for many embedded programmers.
14697 If you have ported some library or want to share experience about some code
14699 falls into any of these categories Busses (I
14700 \begin_inset Formula $^{\textrm{2}}$
14703 C, CAN, Ethernet, Profibus, Modbus, USB, SPI, JTAG ...), Media (IDE, Memory
14704 cards, eeprom, flash...), En-/Decryption, Remote debugging, Realtime kernel,
14705 Keyboard, LCD, RTC, FPGA, PID then the sdcc-user mailing list
14706 \begin_inset LatexCommand \url{http://sourceforge.net/mail/?group_id=599}
14711 would certainly like to hear about it.
14712 Programmers coding for embedded systems are not especially famous for being
14713 enthusiastic, so don't expect a big hurray but as the mailing list is searchabl
14714 e these references are very valuable.
14715 Let's help to create a climate where information is shared.
14721 MCS51 Memory Models
14722 \begin_inset LatexCommand \index{Memory model}
14727 \begin_inset LatexCommand \index{MCS51 memory model}
14732 \layout Subsubsection
14737 SDCC allows two memory models for MCS51 code,
14746 Modules compiled with different memory models should
14750 be combined together or the results would be unpredictable.
14751 The library routines supplied with the compiler are compiled as both small
14753 The compiled library modules are contained in separate directories as small
14754 and large so that you can link to either set.
14758 When the large model is used all variables declared without a storage class
14759 will be allocated into the external ram, this includes all parameters and
14760 local variables (for non-reentrant
14761 \begin_inset LatexCommand \index{reentrant}
14766 When the small model is used variables without storage class are allocated
14767 in the internal ram.
14770 Judicious usage of the processor specific storage classes
14771 \begin_inset LatexCommand \index{Storage class}
14775 and the 'reentrant' function type will yield much more efficient code,
14776 than using the large model.
14777 Several optimizations are disabled when the program is compiled using the
14778 large model, it is therefore recommended that the small model be used unless
14779 absolutely required.
14780 \layout Subsubsection
14783 \begin_inset LatexCommand \label{sub:External-Stack}
14788 \begin_inset LatexCommand \index{stack}
14793 \begin_inset LatexCommand \index{External stack (mcs51)}
14800 The external stack (-
14811 \begin_inset LatexCommand \index{-\/-xstack}
14815 ) is located in pdata
14816 \begin_inset LatexCommand \index{pdata (mcs51, ds390 storage class)}
14820 memory (usually at the start of the external ram segment) and uses all
14821 unused space in pdata (max.
14833 -xstack option is used to compile the program, the parameters and local
14835 \begin_inset LatexCommand \index{local variables}
14839 of all reentrant functions are allocated in this area.
14840 This option is provided for programs with large stack space requirements.
14841 When used with the -
14852 \begin_inset LatexCommand \index{-\/-stack-auto}
14856 option, all parameters and local variables are allocated on the external
14857 stack (note: support libraries will need to be recompiled with the same
14859 There is a predefined target in the library makefile).
14862 The compiler outputs the higher order address byte of the external ram segment
14864 \begin_inset LatexCommand \index{P2 (mcs51 sfr)}
14869 \begin_inset LatexCommand \ref{sub:MCS51-variants}
14873 ), therefore when using the External Stack option, this port
14877 be used by the application program.
14881 \begin_inset LatexCommand \index{Memory model}
14886 \begin_inset LatexCommand \index{DS390 memory model}
14893 The only model supported is Flat 24
14894 \begin_inset LatexCommand \index{Flat 24 (DS390 memory model)}
14899 This generates code for the 24 bit contiguous addressing mode of the Dallas
14901 In this mode, up to four meg of external RAM or code space can be directly
14903 See the data sheets at www.dalsemi.com for further information on this part.
14907 Note that the compiler does not generate any code to place the processor
14908 into 24 bitmode (although
14912 in the ds390 libraries will do that for you).
14918 \begin_inset LatexCommand \index{Tinibios (DS390)}
14922 , the boot loader or similar code must ensure that the processor is in 24
14923 bit contiguous addressing mode before calling the SDCC startup code.
14941 option, variables will by default be placed into the XDATA segment.
14946 Segments may be placed anywhere in the 4 meg address space using the usual
14958 Note that if any segments are located above 64K, the -r flag must be passed
14959 to the linker to generate the proper segment relocations, and the Intel
14960 HEX output format must be used.
14961 The -r flag can be passed to the linker by using the option
14965 on the SDCC command line.
14966 However, currently the linker can not handle code segments > 64k.
14970 \begin_inset LatexCommand \index{Pragmas}
14977 SDCC supports the following #pragma directives:
14981 \begin_inset LatexCommand \index{\#pragma save}
14985 - this will save all current options to the save/restore stack.
14986 See #pragma\SpecialChar ~
14991 \begin_inset LatexCommand \index{\#pragma restore}
14995 - will restore saved options from the last save.
14996 saves & restores can be nested.
14997 SDCC uses a save/restore stack: save pushes current options to the stack,
14998 restore pulls current options from the stack.
14999 See #pragma\SpecialChar ~
15006 \begin_inset LatexCommand \index{\#pragma callee\_saves}
15011 \begin_inset LatexCommand \index{function prologue}
15015 function1[,function2[,function3...]] - The compiler by default uses a caller
15016 saves convention for register saving across function calls, however this
15017 can cause unnecessary register pushing & popping
15018 \begin_inset LatexCommand \index{push/pop}
15022 when calling small functions from larger functions.
15023 This option can be used to switch off the register saving convention for
15024 the function names specified.
15025 The compiler will not save registers when calling these functions, extra
15026 code need to be manually inserted at the entry & exit for these functions
15027 to save & restore the registers used by these functions, this can SUBSTANTIALLY
15028 reduce code & improve run time performance of the generated code.
15029 In the future the compiler (with inter procedural analysis) may be able
15030 to determine the appropriate scheme to use for each function call.
15041 -callee-saves command line option is used, the function names specified
15042 in #pragma\SpecialChar ~
15044 \begin_inset LatexCommand \index{\#pragma callee\_saves}
15048 is appended to the list of functions specified in the command line.
15052 \begin_inset LatexCommand \index{\#pragma exclude}
15056 none | {acc[,b[,dpl[,dph]]] - The exclude pragma disables the generation
15057 of pairs of push/pop
15058 \begin_inset LatexCommand \index{push/pop}
15067 \begin_inset LatexCommand \index{interrupt}
15080 The directive should be placed immediately before the ISR function definition
15081 and it affects ALL ISR functions following it.
15082 To enable the normal register saving for ISR functions use #pragma\SpecialChar ~
15083 exclude\SpecialChar ~
15085 \begin_inset LatexCommand \index{\#pragma exclude}
15090 See also the related keyword _naked
15091 \begin_inset LatexCommand \index{\_naked}
15096 \begin_inset LatexCommand \index{\_\_naked}
15104 \begin_inset LatexCommand \index{\#pragma less\_pedantic}
15108 - the compiler will not warn you anymore for obvious mistakes, you'r on
15112 disable_warning <nnnn>
15113 \begin_inset LatexCommand \index{\#pragma disable\_warning}
15117 - the compiler will not warn you anymore about warning number <nnnn>.
15121 \begin_inset LatexCommand \index{\#pragma nogcse}
15125 - will stop global common subexpression elimination.
15129 \begin_inset LatexCommand \index{\#pragma noinduction}
15133 - will stop loop induction optimizations.
15137 \begin_inset LatexCommand \index{\#pragma noinvariant}
15141 - will not do loop invariant optimizations.
15142 For more details see Loop Invariants in section
15143 \begin_inset LatexCommand \ref{sub:Loop-Optimizations}
15151 \begin_inset LatexCommand \index{\#pragma noiv}
15155 - Do not generate interrupt
15156 \begin_inset LatexCommand \index{interrupt}
15160 vector table entries for all ISR functions defined after the pragma.
15161 This is useful in cases where the interrupt vector table must be defined
15162 manually, or when there is a secondary, manually defined interrupt vector
15164 for the autovector feature of the Cypress EZ-USB FX2).
15165 More elegantly this can be achieved by obmitting the optional interrupt
15166 number after the interrupt keyword, see section
15167 \begin_inset LatexCommand \ref{sub:Interrupt-Service-Routines}
15176 \begin_inset LatexCommand \index{\#pragma nojtbound}
15180 - will not generate code for boundary value checking, when switch statements
15181 are turned into jump-tables (dangerous).
15182 For more details see section
15183 \begin_inset LatexCommand \ref{sub:'switch'-Statements}
15191 \begin_inset LatexCommand \index{\#pragma noloopreverse}
15195 - Will not do loop reversal optimization
15199 \begin_inset LatexCommand \index{\#pragma nooverlay}
15203 - the compiler will not overlay the parameters and local variables of a
15208 \begin_inset LatexCommand \index{\#pragma stackauto}
15223 \begin_inset LatexCommand \index{-\/-stack-auto}
15228 \begin_inset LatexCommand \ref{sec:Parameters-and-Local-Variables}
15232 Parameters and Local Variables.
15236 \begin_inset LatexCommand \index{\#pragma opt\_code\_speed}
15240 - The compiler will optimize code generation towards fast code, possibly
15241 at the expense of code size.
15245 \begin_inset LatexCommand \index{\#pragma opt\_code\_size}
15249 - The compiler will optimize code generation towards compact code, possibly
15250 at the expense of code speed.
15254 \begin_inset LatexCommand \index{\#pragma opt\_code\_balanced}
15258 - The compiler will attempt to generate code that is both compact and fast,
15259 as long as meeting one goal is not a detriment to the other (this is the
15265 \begin_inset LatexCommand \index{\#pragma std\_sdcc89}
15269 - Generally follow the C89 standard, but allow SDCC features that conflict
15270 with the standard (default).
15274 \begin_inset LatexCommand \index{\#pragma std\_c89}
15278 - Follow the C89 standard and disable SDCC features that conflict with the
15283 \begin_inset LatexCommand \index{\#pragma std\_sdcc99}
15287 - Generally follow the C99 standard, but allow SDCC features that conflict
15288 with the standard (incomplete support).
15292 \begin_inset LatexCommand \index{\#pragma std\_c99}
15296 - Follow the C99 standard and disable SDCC features that conflict with the
15297 standard (incomplete support).
15301 \begin_inset LatexCommand \index{\#pragma codeseg}
15305 - Use this name (max.
15306 8 characters) for the code segment.
15310 \begin_inset LatexCommand \index{\#pragma constseg}
15314 - Use this name (max.
15315 8 characters) for the const segment.
15318 SDCPP supports the following #pragma directives:
15322 \begin_inset LatexCommand \index{\#pragma preproc\_asm}
15326 (+ | -) - switch _asm _endasm block preprocessing on / off.
15330 The pragma's are intended to be used to turn-on or off certain optimizations
15331 which might cause the compiler to generate extra stack / data space to
15332 store compiler generated temporary variables.
15333 This usually happens in large functions.
15334 Pragma directives should be used as shown in the following example, they
15335 are used to control options & optimizations for a given function; pragmas
15336 should be placed before and/or after a function, placing pragma's inside
15337 a function body could have unpredictable results.
15343 \begin_inset LatexCommand \index{\#pragma save}
15354 /* save the current settings */
15357 \begin_inset LatexCommand \index{\#pragma nogcse}
15366 /* turnoff global subexpression elimination */
15368 #pragma noinduction
15369 \begin_inset LatexCommand \index{\#pragma noinduction}
15373 /* turn off induction optimizations */
15396 \begin_inset LatexCommand \index{\#pragma restore}
15400 /* turn the optimizations back on */
15403 The compiler will generate a warning message when extra space is allocated.
15404 It is strongly recommended that the save and restore pragma's be used when
15405 changing options for a function.
15408 Defines Created by the Compiler
15411 The compiler creates the following #defines
15412 \begin_inset LatexCommand \index{\#defines}
15417 \begin_inset LatexCommand \index{Defines created by the compiler}
15427 \begin_inset Tabular
15428 <lyxtabular version="3" rows="10" columns="2">
15430 <column alignment="center" valignment="top" leftline="true" width="0">
15431 <column alignment="center" valignment="top" leftline="true" rightline="true" width="0">
15432 <row topline="true" bottomline="true">
15433 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
15443 <cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
15454 <row topline="true">
15455 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
15461 \begin_inset LatexCommand \index{SDCC}
15468 <cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
15473 this Symbol is always defined
15477 <row topline="true">
15478 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
15484 \begin_inset LatexCommand \index{SDCC\_mcs51}
15489 \begin_inset LatexCommand \index{SDCC\_ds390}
15494 \begin_inset LatexCommand \index{SDCC\_z80}
15501 <cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
15506 depending on the model used (e.g.: -mds390
15510 <row topline="true">
15511 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
15517 \begin_inset LatexCommand \index{\_\_mcs51}
15522 \begin_inset LatexCommand \index{\_\_ds390}
15527 \begin_inset LatexCommand \index{\_\_hc08}
15532 \begin_inset LatexCommand \index{\_\_z80}
15539 <cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
15544 depending on the model used (e.g.
15549 <row topline="true">
15550 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
15556 \begin_inset LatexCommand \index{SDCC\_STACK\_AUTO}
15563 <cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
15586 <row topline="true">
15587 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
15593 \begin_inset LatexCommand \index{SDCC\_MODEL\_SMALL}
15600 <cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
15623 <row topline="true">
15624 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
15630 \begin_inset LatexCommand \index{SDCC\_MODEL\_LARGE}
15637 <cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
15660 <row topline="true">
15661 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
15667 \begin_inset LatexCommand \index{SDCC\_USE\_XSTACK}
15674 <cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
15697 <row topline="true">
15698 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
15704 \begin_inset LatexCommand \index{SDCC\_STACK\_TENBIT}
15711 <cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
15724 <row topline="true" bottomline="true">
15725 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
15731 \begin_inset LatexCommand \index{SDCC\_MODEL\_FLAT24}
15738 <cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
15758 Notes on supported Processors
15762 \begin_inset LatexCommand \label{sub:MCS51-variants}
15767 \begin_inset LatexCommand \index{MCS51 variants}
15774 MCS51 processors are available from many vendors and come in many different
15776 While they might differ considerably in respect to Special Function Registers
15777 the core MCS51 is usually not modified or is kept compatible.
15781 pdata access by SFR
15784 With the upcome of devices with internal xdata and flash memory devices
15786 \begin_inset LatexCommand \index{P2 (mcs51 sfr)}
15790 as dedicated I/O port is becoming more popular.
15791 Switching the high byte for pdata
15792 \begin_inset LatexCommand \index{pdata (mcs51, ds390 storage class)}
15796 access which was formerly done by port P2 is then achieved by a Special
15798 \begin_inset LatexCommand \index{sfr}
15803 In well-established MCS51 tradition the address of this
15807 is where the chip designers decided to put it.
15808 Needless to say that they didn't agree on a common name either.
15809 So that the startup code can correctly initialize xdata variables, you
15810 should define an sfr with the name _XPAGE
15813 \begin_inset LatexCommand \index{\_XPAGE (mcs51)}
15819 at the appropriate location if the default, port P2, is not used for this.
15825 sfr at 0x92 _XPAGE; /* Cypress EZ-USB family */
15830 sfr at 0xaf _XPAGE; /* some Silicon Labs (Cygnal) chips */
15835 sfr at 0xaa _XPAGE; /* some Silicon Labs (Cygnal) chips */
15838 For more exotic implementations further customizations may be needed.
15840 \begin_inset LatexCommand \ref{sub:Startup-Code}
15844 for other possibilities.
15847 Other Features available by SFR
15850 Some MCS51 variants offer features like Double DPTR
15851 \begin_inset LatexCommand \index{DPTR}
15855 , multiple DPTR, decrementing DPTR, 16x16 Multiply.
15856 These are currently not used for the MCS51 port.
15857 If you absolutely need them you can fall back to inline assembly or submit
15864 The DS80C400 microcontroller has a rich set of peripherals.
15865 In its built-in ROM library it includes functions to access some of the
15866 features, among them is a TCP stack with IP4 and IP6 support.
15867 Library headers (currently in beta status) and other files are provided
15871 \begin_inset LatexCommand \url{ftp://ftp.dalsemi.com/pub/tini/ds80c400/c_libraries/sdcc/index.html}
15879 The Z80 and gbz80 port
15882 SDCC can target both the Zilog
15883 \begin_inset LatexCommand \index{Z80}
15887 and the Nintendo Gameboy's Z80-like gbz80
15888 \begin_inset LatexCommand \index{gbz80 (GameBoy Z80)}
15893 The Z80 port is passed through the same
15896 \begin_inset LatexCommand \index{Regression test}
15902 as the MCS51 and DS390 ports, so floating point support, support for long
15903 variables and bitfield support is fine.
15904 See mailing lists and forums about interrupt routines.
15907 As always, the code is the authoritative reference - see z80/ralloc.c and
15910 \begin_inset LatexCommand \index{stack}
15914 frame is similar to that generated by the IAR Z80 compiler.
15915 IX is used as the base pointer, HL and IY are used as a temporary registers,
15916 and BC and DE are available for holding variables.
15918 \begin_inset LatexCommand \index{return value}
15922 for the Z80 port are stored in L (one byte), HL (two bytes), or DEHL (four
15924 The gbz80 port use the same set of registers for the return values, but
15925 in a different order of significance: E (one byte), DE (two bytes), or
15932 The port to the Motorola HC08
15933 \begin_inset LatexCommand \index{HC08}
15937 family has been added in October 2003, and is still undergoing some basic
15939 The code generator is complete, but the register allocation is still quite
15941 Some of the SDCC's standard C library functions have embedded non-HC08
15942 inline assembly and so are not yet usable.
15953 \begin_inset LatexCommand \index{PIC14}
15957 port still requires a major effort from the development community.
15958 However it can work for very simple code.
15961 C code and 14bit PIC code page
15962 \begin_inset LatexCommand \index{code page (pic14)}
15967 \begin_inset LatexCommand \index{RAM bank (pic14)}
15974 The linker organizes allocation for the code page and RAM banks.
15975 It does not have intimate knowledge of the code flow.
15976 It will put all the code section of a single asm file into a single code
15978 In order to make use of multiple code pages, separate asm files must be
15980 The compiler treats all functions of a single C file as being in the same
15981 code page unless it is non static.
15982 The compiler treats all local variables of a single C file as being in
15983 the same RAM bank unless it is an extern.
15987 To get the best follow these guide lines:
15990 make local functions static, as non static functions require code page selection
15994 Make local variables static as extern variables require RAM bank selection
15998 For devices that have multiple code pages it is more efficient to use the
15999 same number of files as pages, i.e.
16000 for the 16F877 use 4 separate files and i.e.
16001 for the 16F874 use 2 separate files.
16002 This way the linker can put the code for each file into different code
16003 pages and the compiler can allocate reusable variables more efficiently
16004 and there's less page selection overhead.
16005 And as for any 8 bit micro (especially for PIC 14 as they have a very simple
16006 instruction set) use 'unsigned char' whereever possible instead of 'int'.
16009 Creating a device include file
16012 For generating a device include file use the support perl script inc2h.pl
16013 kept in directory support/script.
16019 For the interrupt function, use the keyword 'interrupt'
16020 \begin_inset LatexCommand \index{interrupt}
16024 with level number of 0 (PIC14 only has 1 interrupt so this number is only
16025 there to avoid a syntax error - it ought to be fixed).
16031 void Intr(void) interrupt 0
16037 T0IF = 0; /* Clear timer interrupt */
16042 Linking and assembling
16045 For assembling you can use either GPUTILS'
16046 \begin_inset LatexCommand \index{gputils (pic tools)}
16050 gpasm.exe or MPLAB's mpasmwin.exe.
16051 GPUTILS is available from
16052 \begin_inset LatexCommand \url{http://sourceforge.net/projects/gputils}
16057 For linking you can use either GPUTIL's gplink or MPLAB's mplink.exe.
16058 If you use MPLAB and an interrupt function then the linker script file
16059 vectors section will need to be enlarged to link with mplink.
16082 sdcc -S -V -mpic14 -p16F877 $<
16096 $(PRJ).hex: $(OBJS)
16106 gplink -m -s $(PRJ).lkr -o $(PRJ).hex $(OBJS)
16128 sdcc -S -V -mpic14 -p16F877 $<
16138 mpasmwin /q /o $*.asm
16142 $(PRJ).hex: $(OBJS)
16152 mplink /v $(PRJ).lkr /m $(PRJ).map /o $(PRJ).hex $(OBJS)
16155 Please note that indentations within a
16159 have to be done with a tabulator character.
16163 \begin_inset LatexCommand \index{PIC16}
16171 \begin_inset LatexCommand \index{PIC16}
16175 port is the portion of SDCC that is responsible to produce code for the
16177 \begin_inset LatexCommand \index{Microchip}
16181 (TM) microcontrollers with 16 bit core.
16182 Currently this family of microcontrollers contains the PIC18Fxxx and PIC18Fxxxx.
16183 Currently supported devices are:
16187 \begin_inset Tabular
16188 <lyxtabular version="3" rows="4" columns="6">
16190 <column alignment="center" valignment="top" leftline="true" width="0">
16191 <column alignment="center" valignment="top" leftline="true" width="0">
16192 <column alignment="center" valignment="top" leftline="true" width="0">
16193 <column alignment="center" valignment="top" leftline="true" width="0">
16194 <column alignment="center" valignment="top" leftline="true" width="0">
16195 <column alignment="center" valignment="top" leftline="true" rightline="true" width="0">
16196 <row topline="true">
16197 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
16205 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
16213 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
16221 <cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
16229 <cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
16237 <cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
16246 <row topline="true">
16247 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
16255 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
16263 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
16271 <cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
16279 <cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
16287 <cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
16296 <row topline="true">
16297 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
16305 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
16313 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
16321 <cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
16329 <cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
16337 <cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
16346 <row topline="true" bottomline="true">
16347 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
16355 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
16363 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
16371 <cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
16378 <cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
16385 <cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
16403 PIC16 port supports the standard command line arguments as supposed, with
16404 the exception of certain cases that will be mentioned in the following
16407 \labelwidthstring 00.00.0000
16419 -callee-saves See -
16431 \labelwidthstring 00.00.0000
16443 -all-callee-saves All function arguments are passed on stack by default.
16446 There is no need to specify this in the command line.
16448 \labelwidthstring 00.00.0000
16460 -fommit-frame-pointer Frame pointer will be omitted when the function uses
16461 no local variables.
16464 Port Specific Options
16465 \begin_inset LatexCommand \index{Options PIC16}
16472 The port specific options appear after the global options in the sdcc --help
16474 \layout Subsubsection
16479 General options enable certain port features and optimizations.
16481 \labelwidthstring 00.00.0000
16493 -stack-model=[model] Used in conjuction with the command above.
16494 Defines the stack model to be used, valid stack models are :
16497 \labelwidthstring 00.00.0000
16503 Selects small stack model.
16504 8 bit stack and frame pointers.
16505 Supports 256 bytes stack size.
16507 \labelwidthstring 00.00.0000
16513 Selects large stack model.
16514 16 bit stack and frame pointers.
16515 Supports 65536 bytes stack size.
16518 \labelwidthstring 00.00.0000
16530 -preplace-udata-with=[kword] Replaces the default udata keyword for allocating
16531 unitialized data variables with [kword].
16532 Valid keywords are: "udata_acs", "udata_shr", "udata_ovr".
16534 \labelwidthstring 00.00.0000
16546 -ivt-loc <nnnn> positions the Interrupt Vector Table at location <nnnn>.
16547 Useful for bootloaders.
16549 \labelwidthstring 00.00.0000
16561 -asm= sets the full path and name of an external assembler to call.
16563 \labelwidthstring 00.00.0000
16575 -link= sets the full path and name of an external linker to call.
16577 \labelwidthstring 00.00.0000
16589 -mplab-comp MPLAB compatibility option.
16590 Currently only suppresses special gpasm directives.
16591 \layout Subsubsection
16593 Optimization Options
16595 \labelwidthstring 00.00.0000
16607 -optimize-goto Try to use (conditional) BRA instead of GOTO
16609 \labelwidthstring 00.00.0000
16621 -optimize-cmp Try to optimize some compares.
16623 \labelwidthstring 00.00.0000
16635 -obanksel=nn Set optimization level for inserting BANKSELs.
16640 \labelwidthstring 00.00.0000
16644 \labelwidthstring 00.00.0000
16646 1 checks previous used register and if it is the same then does not emit
16647 BANKSEL, accounts only for labels.
16649 \labelwidthstring 00.00.0000
16651 2 tries to check the location of (even different) symbols and removes BANKSELs
16652 if they are in the same bank.
16657 Important: There might be problems if the linker script has data sections
16658 across bank borders!
16660 \layout Subsubsection
16664 \labelwidthstring 00.00.0000
16676 -nodefaultlibs do not link default libraries when linking
16678 \labelwidthstring 00.00.0000
16690 -no-crt Don't link the default run-time modules
16692 \labelwidthstring 00.00.0000
16704 -use-crt= Use a custom run-time module instead of the defaults.
16705 \layout Subsubsection
16710 Debugging options enable extra debugging information in the output files.
16712 \labelwidthstring 00.00.0000
16724 -debug-xtra Similar to -
16735 \begin_inset LatexCommand \index{-\/-debug}
16739 , but dumps more information.
16741 \labelwidthstring 00.00.0000
16753 -debug-ralloc Force register allocator to dump <source>.d file with debugging
16755 <source> is the name of the file compiled.
16757 \labelwidthstring 00.00.0000
16769 -pcode-verbose Enable pcode debugging information in translation.
16771 \labelwidthstring 00.00.0000
16783 -denable-peeps Force the usage of peepholes.
16786 \labelwidthstring 00.00.0000
16798 -gstack Trace push/pops for stack pointer overflow
16800 \labelwidthstring 00.00.0000
16812 -call-tree dump call tree in .calltree file
16815 Enviromental Variables
16818 There is a number of enviromental variables that can be used when running
16819 SDCC to enable certain optimizations or force a specific program behaviour.
16820 these variables are primarily for debugging purposes so they can be enabled/dis
16824 Currently there is only two such variables available:
16826 \labelwidthstring 00.00.0000
16828 OPTIMIZE_BITFIELD_POINTER_GET when this variable exists reading of structure
16829 bitfields is optimized by directly loading FSR0 with the address of the
16830 bitfield structure.
16831 Normally SDCC will cast the bitfield structure to a bitfield pointer and
16833 This step saves data ram and code space for functions that perform heavy
16836 80 bytes of code space are saved when compiling malloc.c with this option).
16839 \labelwidthstring 00.00.0000
16841 NO_REG_OPT do not perform pCode registers optimization.
16842 This should be used for debugging purposes.
16843 In some where bugs in the pcode optimizer are found, users can benefit
16844 from temporarily disabling the optimizer until the bug is fixed.
16847 Preprocessor Macros
16850 PIC16 port defines the following preprocessor macros while translating a
16855 \begin_inset Tabular
16856 <lyxtabular version="3" rows="6" columns="2">
16858 <column alignment="center" valignment="top" leftline="true" width="0">
16859 <column alignment="center" valignment="top" leftline="true" rightline="true" width="0">
16860 <row topline="true" bottomline="true">
16861 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
16869 <cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
16878 <row topline="true">
16879 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
16887 <cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
16892 Port identification
16896 <row topline="true">
16897 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
16915 <cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
16920 Port identification (same as above)
16924 <row topline="true">
16925 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
16933 <cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
16938 MCU Identification.
16943 is the microcontrol identification number, i.e.
16948 <row topline="true">
16949 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
16967 <cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
16972 MCU Identification (same as above)
16976 <row topline="true" bottomline="true">
16977 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
16985 <cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
16990 nnn = SMALL or LARGE respectively according to the stack model used
17001 In addition the following macros are defined when calling assembler:
17005 \begin_inset Tabular
17006 <lyxtabular version="3" rows="4" columns="2">
17008 <column alignment="center" valignment="top" leftline="true" width="0">
17009 <column alignment="center" valignment="top" leftline="true" rightline="true" width="0">
17010 <row topline="true" bottomline="true">
17011 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
17019 <cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
17028 <row topline="true">
17029 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
17037 <cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
17042 MCU Identification.
17047 is the microcontrol identification number, i.e.
17052 <row topline="true">
17053 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
17061 <cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
17066 nnn = SMALL or LARGE respectively according to the memory model used for
17071 <row topline="true" bottomline="true">
17072 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
17080 <cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
17085 nnn = SMALL or LARGE respectively according to the stack model used
17100 \begin_inset LatexCommand \index{PIC16}
17104 port uses the following directories for searching header files and libraries.
17108 \begin_inset Tabular
17109 <lyxtabular version="3" rows="3" columns="4">
17111 <column alignment="center" valignment="top" leftline="true" width="0">
17112 <column alignment="center" valignment="top" leftline="true" rightline="true" width="0">
17113 <column alignment="center" valignment="top" width="0">
17114 <column alignment="center" valignment="top" leftline="true" rightline="true" width="0">
17115 <row topline="true" bottomline="true">
17116 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
17124 <cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
17132 <cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
17140 <cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
17149 <row topline="true">
17150 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
17155 PREFIX/sdcc/include/pic16
17158 <cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
17163 PIC16 specific headers
17166 <cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
17174 <cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
17183 <row topline="true" bottomline="true">
17184 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
17189 PREFIX/sdcc/lib/pic16
17192 <cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
17197 PIC16 specific libraries
17200 <cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
17208 <cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
17225 \begin_inset LatexCommand \label{sub:PIC16_Pragmas}
17232 PIC16 port currently supports the following pragmas:
17234 \labelwidthstring 00.00.0000
17236 stack pragma stack forces the code generator to initialize the stack & frame
17237 pointers at a specific address.
17238 This is an adhoc solution for cases where no STACK directive is available
17239 in the linker script or gplink is not instructed to create a stack section.
17241 The stack pragma should be used only once in a project.
17242 Multiple pragmas may result in indeterminate behaviour of the program.
17248 The old format (ie.
17249 #pragma stack 0x5ff) is deprecated and will cause the stack pointer to
17250 cross page boundaries (or even exceed the available data RAM) and crash
17252 Make sure that stack does not cross page boundaries when using the SMALL
17258 The format is as follows:
17261 #pragma stack bottom_address [stack_size]
17268 is the lower bound of the stack section.
17269 The stack pointer initially will point at address (bottom_address+stack_size-1).
17277 /* initializes stack of 100 bytes at RAM address 0x200 */
17280 #pragma stack 0x200 100
17283 If the stack_size field is omitted then a stack is created with the default
17285 This size might be enough for most programs, but its not enough for operations
17286 with deep function nesting or excessive stack usage.
17288 \labelwidthstring 00.00.0000
17292 This pragma is deprecated.
17293 Its use will cause a warning message to be issued.
17299 \labelwidthstring 00.00.0000
17301 code place a function symbol at static FLASH address
17309 /* place function test_func at 0x4000 */
17312 #pragma code test_func 0x4000
17316 \labelwidthstring 00.00.0000
17318 library instructs the linker to use a library module.
17323 #pragma library module_name
17330 can be any library or object file (including its path).
17331 Note that there are four reserved keywords which have special meaning.
17336 \begin_inset Tabular
17337 <lyxtabular version="3" rows="6" columns="3">
17339 <column alignment="center" valignment="top" leftline="true" width="0">
17340 <column alignment="block" valignment="top" leftline="true" width="20page%">
17341 <column alignment="left" valignment="top" leftline="true" rightline="true" width="0">
17342 <row topline="true" bottomline="true">
17343 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
17351 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
17359 <cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
17368 <row topline="true">
17369 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
17379 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
17384 ignore all library pragmas
17387 <cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
17398 <row topline="true">
17399 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
17409 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
17417 <cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
17430 <row topline="true">
17431 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
17441 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
17446 link the Math libarary
17449 <cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
17462 <row topline="true">
17463 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
17473 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
17478 link the I/O library
17481 <cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
17494 <row topline="true" bottomline="true">
17495 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
17505 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
17510 link the debug library
17513 <cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
17532 * is the device number, i.e.
17533 452 for PIC18F452 MCU.
17536 This feature allows for linking with specific libraries withoug having to
17537 explicit name them in the command line.
17542 keyword will reject all modules specified by the library pragma.
17544 \labelwidthstring 00.00.0000
17546 udata pragma udata instructs the compiler to emit code so that linker will
17547 place a variable at a specific memory bank
17555 /* places variable foo at bank2 */
17558 #pragma udata bank2 foo
17564 In order for this pragma to work extra SECTION directives should be added
17565 in the .lkr script.
17566 In the following example a sample .lkr file is shown:
17571 // Sample linker script for the PIC18F452 processor
17577 CODEPAGE NAME=vectors START=0x0 END=0x29 PROTECTED
17580 CODEPAGE NAME=page START=0x2A END=0x7FFF
17583 CODEPAGE NAME=idlocs START=0x200000 END=0x200007 PROTECTED
17586 CODEPAGE NAME=config START=0x300000 END=0x30000D PROTECTED
17589 CODEPAGE NAME=devid START=0x3FFFFE END=0x3FFFFF PROTECTED
17592 CODEPAGE NAME=eedata START=0xF00000 END=0xF000FF PROTECTED
17595 ACCESSBANK NAME=accessram START=0x0 END=0x7F
17600 DATABANK NAME=gpr0 START=0x80 END=0xFF
17603 DATABANK NAME=gpr1 START=0x100 END=0x1FF
17606 DATABANK NAME=gpr2 START=0x200 END=0x2FF
17609 DATABANK NAME=gpr3 START=0x300 END=0x3FF
17612 DATABANK NAME=gpr4 START=0x400 END=0x4FF
17615 DATABANK NAME=gpr5 START=0x500 END=0x5FF
17618 ACCESSBANK NAME=accesssfr START=0xF80 END=0xFFF PROTECTED
17623 SECTION NAME=CONFIG ROM=config
17628 SECTION NAME=bank0 RAM=gpr0 # these SECTION directives
17631 SECTION NAME=bank1 RAM=gpr1 # should be added to link
17634 SECTION NAME=bank2 RAM=gpr2 # section name 'bank?' with
17637 SECTION NAME=bank3 RAM=gpr3 # a specific DATABANK name
17640 SECTION NAME=bank4 RAM=gpr4
17643 SECTION NAME=bank5 RAM=gpr5
17646 The linker will recognise the section name set in the pragma statement and
17647 will position the variable at the memory bank set with the RAM field at
17648 the SECTION line in the linker script file.
17652 \begin_inset LatexCommand \label{sub:PIC16_Header-Files}
17659 There is one main header file that can be included to the source files using
17666 This header file contains the definitions for the processor special registers,
17667 so it is necessary if the source accesses them.
17668 It can be included by adding the following line in the beginning of the
17672 #include <pic18fregs.h>
17675 The specific microcontroller is selected within the pic18fregs.h automatically,
17676 so the same source can be used with a variety of devices.
17682 The libraries that PIC16
17683 \begin_inset LatexCommand \index{PIC16}
17687 port depends on are the microcontroller device libraries which contain
17688 the symbol definitions for the microcontroller special function registers.
17689 These libraries have the format pic18fxxxx.lib, where
17693 is the microcontroller identification number.
17694 The specific library is selected automatically by the compiler at link
17695 stage according to the selected device.
17698 Libraries are created with gplib which is part of the gputils package
17699 \begin_inset LatexCommand \url{http://sourceforge.net/projects/gputils}
17704 \layout Subsubsection*
17706 Building the libraries
17709 Before using SDCC/pic16 there are some libraries that need to be compiled.
17710 This process is not done automatically by SDCC since not all users use
17711 SDCC for pic16 projects.
17712 So each user should compile the libraries separately.
17715 The steps to compile the pic16 libraries under Linux are:
17718 cd device/lib/pic16
17733 su -c 'make install' # install the libraries, you need the root password
17736 If you need to install the headers too, do:
17742 su -c 'make install' # install the headers, you need the root password
17745 There exist a special target to build the I/O libraries.
17746 This target is not automatically build because it will build the I/O library
17752 This way building will take quite a lot of time.
17753 Users are advised to edit the
17755 device/lib/pic16/pics.build
17757 file and then execute:
17766 The following memory models are supported by the PIC16 port:
17775 Memory model affects the default size of pointers within the source.
17776 The sizes are shown in the next table:
17780 \begin_inset Tabular
17781 <lyxtabular version="3" rows="3" columns="3">
17783 <column alignment="center" valignment="top" leftline="true" rightline="true" width="0">
17784 <column alignment="center" valignment="top" leftline="true" width="0">
17785 <column alignment="center" valignment="top" leftline="true" rightline="true" width="0">
17786 <row topline="true" bottomline="true">
17787 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
17792 Pointer sizes according to memory model
17795 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
17803 <cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
17812 <row topline="true" bottomline="true">
17813 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
17821 <cell multicolumn="1" alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
17829 <cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
17838 <row topline="true" bottomline="true">
17839 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
17847 <cell multicolumn="1" alignment="center" valignment="top" topline="true" bottomline="true" leftline="true" usebox="none">
17855 <cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
17871 It is advisable that all sources within a project are compiled with the
17873 If one wants to override the default memory model, this can be done by
17874 declaring a pointer as
17883 Far selects large memory model's pointers, while near selects small memory
17887 The standard device libraries (see
17888 \begin_inset LatexCommand \ref{sub:PIC16_Header-Files}
17892 ) contain no reference to pointers, so they can be used with both memory
17899 The stack implementation for the PIC16 port uses two indirect registers,
17902 \labelwidthstring 00.00.0000
17904 FSR1 is assigned as stack pointer
17906 \labelwidthstring 00.00.0000
17908 FSR2 is assigned as frame pointer
17911 The following stack models are supported by the PIC16 port
17932 model means that only the FSRxL byte is used to access stack and frame,
17939 uses both FSRxL and FSRxH registers.
17940 The following table shows the stack/frame pointers sizes according to stack
17941 model and the maximum space they can address:
17945 \begin_inset Tabular
17946 <lyxtabular version="3" rows="3" columns="3">
17948 <column alignment="center" valignment="top" leftline="true" rightline="true" width="0">
17949 <column alignment="center" valignment="top" leftline="true" width="0">
17950 <column alignment="center" valignment="top" leftline="true" rightline="true" width="0">
17951 <row topline="true" bottomline="true">
17952 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
17957 Stack & Frame pointer sizes according to stack model
17960 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
17968 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
17977 <row topline="true">
17978 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
17986 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
17994 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
18003 <row topline="true" bottomline="true">
18004 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
18012 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
18020 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
18040 stack model is currently not working properly throughout the code generator.
18041 So its use is not advised.
18042 Also there are some other points that need special care:
18047 Do not create stack sections with size more than one physical bank (that
18051 Stack sections should no cross physical bank limits (i.e.
18052 #pragma stack 0x50 0x100)
18055 These limitations are caused by the fact that only FSRxL is modified when
18056 using SMALL stack model, so no more than 256 bytes of stack can be used.
18057 This problem will disappear after LARGE model is fully implemented.
18063 In addition to the standard SDCC function keywords, PIC16 port makes available
18066 \labelwidthstring 00.00.0000
18068 wparam Use the WREG to pass one byte of the first function argument.
18069 This improves speed but you may not use this for functions with arguments
18070 that are called via function pointers, otherwise the first byte of the
18071 first parameter will get lost.
18075 void func_wparam(int a) wparam
18081 /* WREG hold the lower part of a */
18084 /* the high part of a is stored in FSR2+2 (or +3 for large stack model)
18094 This keyword replaces the deprecated wparam pragma.
18096 \labelwidthstring 00.00.0000
18098 shadowregs When entering/exiting an ISR, it is possible to take advantage
18099 of the PIC18F hardware shadow registers which hold the values of WREG,
18100 STATUS and BSR registers.
18101 This can be done by adding the keyword
18109 keyword in the function's header.
18112 void isr_shadow(void) shadowregs interrupt 1
18128 instructs the code generator not to store/restore WREG, STATUS, BSR when
18129 entering/exiting the ISR.
18132 Function return values
18135 Return values from functions are placed to the appropriate registers following
18136 a modified Microchip policy optimized for SDCC.
18137 The following table shows these registers:
18141 \begin_inset Tabular
18142 <lyxtabular version="3" rows="6" columns="2">
18144 <column alignment="center" valignment="top" leftline="true" width="0">
18145 <column alignment="center" valignment="top" leftline="true" rightline="true" width="0">
18146 <row topline="true" bottomline="true">
18147 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
18155 <cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
18160 destination register
18164 <row topline="true">
18165 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
18173 <cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
18182 <row topline="true">
18183 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
18191 <cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
18200 <row topline="true">
18201 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
18209 <cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
18218 <row topline="true">
18219 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
18227 <cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
18232 FSR0L:PRODH:PRODL:WREG
18236 <row topline="true" bottomline="true">
18237 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
18245 <cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
18250 on stack, FSR0 points to the beginning
18264 An interrupt servive routine (ISR) is declared using the
18271 void isr(void) interrupt
18289 is the interrupt number, which for PIC18F devices can be:
18293 \begin_inset Tabular
18294 <lyxtabular version="3" rows="4" columns="3">
18296 <column alignment="center" valignment="top" leftline="true" width="0">
18297 <column alignment="center" valignment="top" leftline="true" width="0">
18298 <column alignment="center" valignment="top" leftline="true" rightline="true" width="0">
18299 <row topline="true" bottomline="true">
18300 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
18310 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
18318 <cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
18323 Interrupt Vector Address
18327 <row topline="true">
18328 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
18336 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
18344 <cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
18353 <row topline="true">
18354 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
18371 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
18385 HIGH priority interrupts
18388 <cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
18397 <row topline="true" bottomline="true">
18398 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
18406 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
18411 LOW priority interrupts
18414 <cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
18430 When generating assembly code for ISR the code generator places a
18436 Interrupt Vector Address
18438 which points at the genetated ISR.
18439 This single GOTO instruction is part of an automatically generated
18441 interrupt entry point
18444 The actuall ISR code is placed as normally would in the code space.
18445 Upon interrupt request, the GOTO instruction is executed which jumps to
18447 When declaring interrupt functions as _naked this GOTO instruction is
18452 The whole interrupt functions is therefore placed at the Interrupt Vector
18453 Address of the specific interrupt.
18454 This is not a problem for the LOW priority interrupts, but it is a problem
18455 for the RESET and the HIGH priority interrupts because code may be written
18456 at the next interrupt´s vector address and cause undeterminate program
18457 behaviour if that interrupt is raised.
18463 This is not a problem when
18466 this is a HIGH interrupt ISR and LOW interrupts are
18473 when the ISR is small enough not to reach the next interrupt´s vector address.
18483 is possible to be omitted.
18484 This way a function is generated similar to an ISR, but it is not assigned
18488 When entering an interrupt, currently the PIC16
18489 \begin_inset LatexCommand \index{PIC16}
18493 port automatically saves the following registers:
18505 PROD (PRODL and PRODH)
18508 FSR0 (FSR0L and FSR0H)
18511 These registers are restored upon return from the interrupt routine.
18517 NOTE that when the _naked attribute is specified for an interrupt routine,
18518 then NO registers are stored or restored.
18527 Generic pointers are implemented in PIC16 port as 3-byte (24-bit) types.
18528 There are 3 types of generic pointers currently implemented data, code
18529 and eeprom pointers.
18530 They are differentiated by the value of the 7th and 6th bits of the upper
18535 \begin_inset Tabular
18536 <lyxtabular version="3" rows="5" columns="5">
18538 <column alignment="center" valignment="top" leftline="true" rightline="true" width="0">
18539 <column alignment="center" valignment="top" width="0">
18540 <column alignment="center" valignment="top" leftline="true" rightline="true" width="0">
18541 <column alignment="center" valignment="top" width="0">
18542 <column alignment="left" valignment="top" rightline="true" width="0">
18543 <row topline="true" bottomline="true">
18544 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
18552 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
18560 <cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
18568 <cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
18573 rest of the pointer
18576 <cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
18585 <row topline="true" bottomline="true">
18586 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
18594 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
18602 <cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
18610 <cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
18619 uuuuuu uuuuxxxx xxxxxxxx
18622 <cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
18627 a 12-bit data pointer in data RAM memory
18631 <row bottomline="true">
18632 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
18640 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
18648 <cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
18656 <cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
18665 uxxxxx xxxxxxxx xxxxxxxx
18668 <cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
18673 a 21-bit code pointer in FLASH memory
18677 <row bottomline="true">
18678 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
18686 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
18694 <cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
18702 <cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
18711 uuuuuu uuuuuuxx xxxxxxxx
18714 <cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
18719 a 10-bit eeprom pointer in EEPROM memory
18723 <row bottomline="true">
18724 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
18732 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
18740 <cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
18748 <cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
18757 xxxxxx xxxxxxxx xxxxxxxx
18760 <cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
18765 unimplemented pointer type
18776 Generic pointer are read and written with a set of library functions which
18777 read/write 1, 2, 3, 4 bytes.
18781 \layout Subsubsection
18783 Standard I/O Streams
18790 the type FILE is defined as:
18793 typedef char * FILE;
18796 This type is the stream type implemented I/O in the PIC18F devices.
18797 Also the standard input and output streams are declared in stdio.h:
18800 extern FILE * stdin;
18803 extern FILE * stdout;
18806 The FILE type is actually a generic pointer which defines one more type
18807 of generic pointers, the
18812 This new type has the format:
18816 \begin_inset Tabular
18817 <lyxtabular version="3" rows="2" columns="7">
18819 <column alignment="center" valignment="top" leftline="true" rightline="true" width="0">
18820 <column alignment="center" valignment="top" width="0">
18821 <column alignment="center" valignment="top" leftline="true" width="0">
18822 <column alignment="center" valignment="top" leftline="true" width="0">
18823 <column alignment="center" valignment="top" leftline="true" rightline="true" width="0">
18824 <column alignment="center" valignment="top" width="0">
18825 <column alignment="left" valignment="top" rightline="true" width="0">
18826 <row topline="true" bottomline="true">
18827 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
18835 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
18843 <cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
18851 <cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
18859 <cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
18867 <cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
18872 rest of the pointer
18875 <cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
18884 <row topline="true" bottomline="true">
18885 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
18893 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
18901 <cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
18909 <cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
18917 <cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
18925 <cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
18937 <cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
18942 upper byte high nubble is 0x2n, the rest are zeroes
18953 Currently implemented there are 3 types of streams defined:
18957 \begin_inset Tabular
18958 <lyxtabular version="3" rows="4" columns="4">
18960 <column alignment="center" valignment="top" leftline="true" width="0">
18961 <column alignment="center" valignment="top" leftline="true" width="0">
18962 <column alignment="center" valignment="top" leftline="true" width="0">
18963 <column alignment="center" valignment="top" leftline="true" rightline="true" width="0">
18964 <row topline="true" bottomline="true">
18965 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
18973 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
18981 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
18989 <cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
18998 <row topline="true">
18999 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
19007 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
19017 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
19025 <cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
19030 Writes/Reads characters via the USART peripheral
19034 <row topline="true">
19035 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
19043 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
19053 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
19061 <cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
19066 Writes/Reads characters via the MSSP peripheral
19070 <row topline="true" bottomline="true">
19071 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
19079 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
19089 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
19097 <cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
19102 Writes/Reads characters via used defined functions
19113 The stream identifiers are declared as macros in the stdio.h header.
19116 In the libc library there exist the functions that are used to write to
19117 each of the above streams.
19120 \labelwidthstring 00.00.0000
19132 _stream_usart_putchar writes a character at the USART stream
19134 \labelwidthstring 00.00.0000
19146 _stream_mssp_putchar writes a character at the MSSP stream
19148 \labelwidthstring 00.00.0000
19150 putchar dummy function.
19151 This writes a character to a user specified manner.
19154 In order to increase performance
19158 is declared in stdio.h as having its parameter in WREG (it has the wparam
19160 In stdio.h exists the macro PUTCHAR(arg) that defines the putchar function
19161 in a user-friendly way.
19166 is the name of the variable that holds the character to print.
19167 An example follows:
19170 #include <pic18fregs.h>
19182 PORTA = c; /* dump character c to PORTA */
19195 stdout = STREAM_USER; /* this is not necessery, since stdout points
19198 * by default to STREAM_USER */
19201 printf (¨This is a printf test
19209 \layout Subsubsection
19214 PIC16 contains an implementation of the printf-family of functions.
19215 There exist the following functions:
19218 extern unsigned int sprintf(char *buf, char *fmt, ...);
19221 extern unsigned int vsprintf(char *buf, char *fmt, va_list ap);
19226 extern unsigned int printf(char *fmt, ...);
19229 extern unsigned int vprintf(char *fmt, va_lista ap);
19234 extern unsigned int fprintf(FILE *fp, char *fmt, ...);
19237 extern unsigned int vfprintf(FILE *fp, char *fmt, va_list ap);
19240 For sprintf and vsprintf
19244 should normally be a data pointer where the resulting string will be placed.
19245 No range checking is done so the user should allocate the necessery buffer.
19246 For fprintf and vfprintf
19250 should be a stream pointer (i.e.
19251 stdout, STREAM_MSSP, etc...).
19252 \layout Subsubsection
19257 The PIC18F family of microcontrollers supports a number of interrupt sources.
19258 A list of these interrupts is shown in the following table:
19262 \begin_inset Tabular
19263 <lyxtabular version="3" rows="11" columns="4">
19265 <column alignment="left" valignment="top" leftline="true" width="0">
19266 <column alignment="center" valignment="top" leftline="true" rightline="true" width="0">
19267 <column alignment="left" valignment="top" leftline="true" width="0">
19268 <column alignment="center" valignment="top" leftline="true" rightline="true" width="0">
19269 <row topline="true" bottomline="true">
19270 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
19278 <cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
19286 <cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
19294 <cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
19303 <row topline="true">
19304 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
19312 <cell multicolumn="1" alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
19317 PORTB change interrupt
19320 <cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
19328 <cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
19333 EEPROM/FLASH write complete interrupt
19337 <row topline="true">
19338 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
19346 <cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
19351 INT0 external interrupt
19354 <cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
19362 <cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
19367 Bus collision interrupt
19371 <row topline="true">
19372 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
19380 <cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
19385 INT1 external interrupt
19388 <cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
19396 <cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
19401 Low voltage detect interrupt
19405 <row topline="true">
19406 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
19414 <cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
19419 INT2 external interrupt
19422 <cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
19430 <cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
19435 Parallel slave port interrupt
19439 <row topline="true">
19440 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
19448 <cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
19453 CCP1 module interrupt
19456 <cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
19464 <cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
19469 AD convertion complete interrupt
19473 <row topline="true">
19474 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
19482 <cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
19487 CCP2 module interrupt
19490 <cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
19498 <cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
19503 USART receive interrupt
19507 <row topline="true">
19508 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
19516 <cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
19521 TMR0 overflow interrupt
19524 <cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
19532 <cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
19537 USART transmit interrupt
19541 <row topline="true">
19542 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
19550 <cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
19555 TMR1 overflow interrupt
19558 <cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
19566 <cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
19571 SSP receive/transmit interrupt
19575 <row topline="true">
19576 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
19584 <cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
19589 TMR2 matches PR2 interrupt
19592 <cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
19599 <cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
19607 <row topline="true" bottomline="true">
19608 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
19616 <cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
19621 TMR3 overflow interrupt
19624 <cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
19631 <cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
19646 The prototypes for these names are defined in the header file
19653 In order to simplify signal handling, a number of macros is provided:
19655 \labelwidthstring 00.00.0000
19657 DEF_INTHIGH(name) begin the definition of the interrupt dispatch table for
19658 high priority interrupts.
19663 is the function name to use.
19665 \labelwidthstring 00.00.0000
19667 DEF_INTLOW(name) begin the definition of the interrupt dispatch table fo
19668 low priority interrupt.
19673 is the function name to use.
19675 \labelwidthstring 00.00.0000
19677 DEF_HANDLER(sig,handler) define a handler for signal
19681 \labelwidthstring 00.00.0000
19683 END_DEF end the declaration of the dispatch table.
19686 Additionally there are two more macros to simplify the declaration of the
19689 \labelwidthstring 00.00.0000
19693 SIGHANDLER(handler)
19695 this declares the function prototype for the
19701 \labelwidthstring 00.00.0000
19703 SIGHANDLERNAKED(handler) same as SIGHANDLER() but declares a naked function.
19706 An example of using the macros above is shown below:
19709 #include <pic18fregs.h>
19712 #include <signal.h>
19716 DEF_INTHIGH(high_int)
19719 DEF_HANDLER(SIG_TMR0, _tmr0_handler)
19722 DEF_HANDLER(SIG_BCOL, _bcol_handler)
19729 SIGHANDLER(_tmr0_handler)
19735 /* action to be taken when timer 0 overflows */
19742 SIGHANDLERNAKED(_bcol_handler)
19751 /* action to be taken when bus collision occurs */
19767 Special care should be taken when using the above scheme:
19770 do not place a colon (;) at the end of the DEF_* and END_DEF macros.
19773 when declaring SIGHANDLERNAKED handler never forget to use
19777 for proper returning.
19783 Here you can find some general tips for compiling programs with SDCC/pic16.
19784 \layout Subsubsection
19789 The default stack size (that is 64 bytes) probably is enough for many programs.
19790 One must take care that when there are many levels of function nesting,
19791 or there is excessive usage of stack, its size should be extended.
19792 An example of such a case is the printf/sprintf family of functions.
19793 If you encounter problems like not being able to print integers, then you
19794 need to set the stack size around the maximum (256 for small stack model).
19795 The following diagram shows what happens when calling printf to print an
19799 printf () --> ltoa () --> ultoa () --> divschar ()
19802 It is should be understood that stack is easily consumed when calling complicate
19804 Using command line arguments like -
19814 -fommit-frame-pointer might reduce stack usage by not creating unnecessery
19816 Other ways to reduce stack usage may exist.
19819 Debugging with SDCDB
19820 \begin_inset LatexCommand \label{cha:Debugging-with-SDCDB}
19825 \begin_inset LatexCommand \index{sdcdb (debugger)}
19832 SDCC is distributed with a source level debugger
19833 \begin_inset LatexCommand \index{Debugger}
19838 The debugger uses a command line interface, the command repertoire of the
19839 debugger has been kept as close to gdb
19840 \begin_inset LatexCommand \index{gdb}
19844 (the GNU debugger) as possible.
19845 The configuration and build process is part of the standard compiler installati
19846 on, which also builds and installs the debugger in the target directory
19847 specified during configuration.
19848 The debugger allows you debug BOTH at the C source and at the ASM source
19850 Sdcdb is available on Unix platforms only.
19853 Compiling for Debugging
19867 \begin_inset LatexCommand \index{-\/-debug}
19871 option must be specified for all files for which debug information is to
19873 The complier generates a .adb file for each of these files.
19874 The linker creates the .cdb
19875 \begin_inset LatexCommand \index{<file>.cdb}
19880 \begin_inset LatexCommand \index{<file>.adb}
19884 files and the address information.
19885 This .cdb is used by the debugger.
19888 How the Debugger Works
19901 -debug option is specified the compiler generates extra symbol information
19902 some of which are put into the assembler source and some are put into the
19904 Then the linker creates the .cdb file from the individual .adb files with
19905 the address information for the symbols.
19906 The debugger reads the symbolic information generated by the compiler &
19907 the address information generated by the linker.
19908 It uses the SIMULATOR (Daniel's S51) to execute the program, the program
19909 execution is controlled by the debugger.
19910 When a command is issued for the debugger, it translates it into appropriate
19911 commands for the simulator.
19914 Starting the Debugger
19917 The debugger can be started using the following command line.
19918 (Assume the file you are debugging has the file name foo).
19932 The debugger will look for the following files.
19935 foo.c - the source file.
19938 foo.cdb - the debugger symbol information file.
19941 foo.ihx - the Intel hex format
19942 \begin_inset LatexCommand \index{Intel hex format}
19949 Command Line Options
19962 -directory=<source file directory> this option can used to specify the directory
19964 The debugger will look into the directory list specified for source, cdb
19966 The items in the directory list must be separated by ':', e.g.
19967 if the source files can be in the directories /home/src1 and /home/src2,
19978 -directory option should be -
19988 -directory=/home/src1:/home/src2.
19989 Note there can be no spaces in the option.
19993 -cd <directory> - change to the <directory>.
19996 -fullname - used by GUI front ends.
19999 -cpu <cpu-type> - this argument is passed to the simulator please see the
20000 simulator docs for details.
20003 -X <Clock frequency > this options is passed to the simulator please see
20004 the simulator docs for details.
20007 -s <serial port file> passed to simulator see the simulator docs for details.
20010 -S <serial in,out> passed to simulator see the simulator docs for details.
20013 -k <port number> passed to simulator see the simulator docs for details.
20019 As mentioned earlier the command interface for the debugger has been deliberatel
20020 y kept as close the GNU debugger gdb, as possible.
20021 This will help the integration with existing graphical user interfaces
20022 (like ddd, xxgdb or xemacs) existing for the GNU debugger.
20023 If you use a graphical user interface for the debugger you can skip this
20025 \layout Subsubsection*
20027 break [line | file:line | function | file:function]
20030 Set breakpoint at specified line or function:
20039 sdcdb>break foo.c:100
20041 sdcdb>break funcfoo
20043 sdcdb>break foo.c:funcfoo
20044 \layout Subsubsection*
20046 clear [line | file:line | function | file:function ]
20049 Clear breakpoint at specified line or function:
20058 sdcdb>clear foo.c:100
20060 sdcdb>clear funcfoo
20062 sdcdb>clear foo.c:funcfoo
20063 \layout Subsubsection*
20068 Continue program being debugged, after breakpoint.
20069 \layout Subsubsection*
20074 Execute till the end of the current function.
20075 \layout Subsubsection*
20080 Delete breakpoint number 'n'.
20081 If used without any option clear ALL user defined break points.
20082 \layout Subsubsection*
20084 info [break | stack | frame | registers ]
20087 info break - list all breakpoints
20090 info stack - show the function call stack.
20093 info frame - show information about the current execution frame.
20096 info registers - show content of all registers.
20097 \layout Subsubsection*
20102 Step program until it reaches a different source line.
20103 Note: pressing <return> repeats the last command.
20104 \layout Subsubsection*
20109 Step program, proceeding through subroutine calls.
20110 \layout Subsubsection*
20115 Start debugged program.
20116 \layout Subsubsection*
20121 Print type information of the variable.
20122 \layout Subsubsection*
20127 print value of variable.
20128 \layout Subsubsection*
20133 load the given file name.
20134 Note this is an alternate method of loading file for debugging.
20135 \layout Subsubsection*
20140 print information about current frame.
20141 \layout Subsubsection*
20146 Toggle between C source & assembly source.
20147 \layout Subsubsection*
20149 ! simulator command
20152 Send the string following '!' to the simulator, the simulator response is
20154 Note the debugger does not interpret the command being sent to the simulator,
20155 so if a command like 'go' is sent the debugger can loose its execution
20156 context and may display incorrect values.
20157 \layout Subsubsection*
20164 My name is Bobby Brown"
20167 Interfacing with DDD
20170 The screenshot was converted from png to eps with:
20171 \begin_inset Quotes sld
20174 bmeps -c -e8f -p3 ddd_example.png >ddd_example.eps
20175 \begin_inset Quotes srd
20178 which produces a pretty compact eps file which is free from compression
20182 The screenshot was included in sdccman.lyx cvs version 1.120 but later removed
20183 as this broke the build system on Sourceforge (pdf-file was broken).
20189 \begin_inset LatexCommand \url{http://cvs.sourceforge.net/viewcvs.py/*checkout*/sdcc/sdcc/doc/figures/ddd_example.eps}
20195 shows a screenshot of a debugging session with DDD
20196 \begin_inset LatexCommand \index{DDD (debugger)}
20200 (Unix only) on a simulated 8032.
20201 The debugging session might not run as smoothly as the screenshot suggests.
20202 The debugger allows setting of breakpoints, displaying and changing variables,
20203 single stepping through C and assembler code.
20206 The source was compiled with
20229 -debug ddd_example.c
20242 and DDD was invoked with
20249 ddd -debugger 'sdcdb -cpu 8032 ddd_example'
20252 Interfacing with XEmacs
20253 \begin_inset LatexCommand \index{XEmacs}
20258 \begin_inset LatexCommand \index{Emacs}
20265 Two files (in emacs lisp) are provided for the interfacing with XEmacs,
20266 sdcdb.el and sdcdbsrc.el.
20267 These two files can be found in the $(prefix)/bin directory after the installat
20269 These files need to be loaded into XEmacs for the interface to work.
20270 This can be done at XEmacs startup time by inserting the following into
20271 your '.xemacs' file (which can be found in your HOME directory):
20277 (load-file sdcdbsrc.el)
20283 .xemacs is a lisp file so the () around the command is REQUIRED.
20284 The files can also be loaded dynamically while XEmacs is running, set the
20285 environment variable 'EMACSLOADPATH' to the installation bin directory
20286 (<installdir>/bin), then enter the following command ESC-x load-file sdcdbsrc.
20287 To start the interface enter the following command:
20301 You will prompted to enter the file name to be debugged.
20306 The command line options that are passed to the simulator directly are bound
20307 to default values in the file sdcdbsrc.el.
20308 The variables are listed below, these values maybe changed as required.
20311 sdcdbsrc-cpu-type '51
20314 sdcdbsrc-frequency '11059200
20317 sdcdbsrc-serial nil
20320 The following is a list of key mapping for the debugger interface.
20331 ;;key\SpecialChar ~
20345 binding\SpecialChar ~
20369 ;;---\SpecialChar ~
20383 -------\SpecialChar ~
20425 sdcdb-next-from-src\SpecialChar ~
20453 sdcdb-back-from-src\SpecialChar ~
20481 sdcdb-cont-from-src\SpecialChar ~
20491 SDCDB continue command
20509 sdcdb-step-from-src\SpecialChar ~
20537 sdcdb-whatis-c-sexp\SpecialChar ~
20547 SDCDB ptypecommand for data at
20614 sdcdbsrc-delete\SpecialChar ~
20628 SDCDB Delete all breakpoints if no arg
20677 given or delete arg (C-u arg x)
20695 sdcdbsrc-frame\SpecialChar ~
20710 SDCDB Display current frame if no arg,
20759 given or display frame arg
20826 sdcdbsrc-goto-sdcdb\SpecialChar ~
20836 Goto the SDCDB output buffer
20854 sdcdb-print-c-sexp\SpecialChar ~
20865 SDCDB print command for data at
20932 sdcdbsrc-goto-sdcdb\SpecialChar ~
20942 Goto the SDCDB output buffer
20960 sdcdbsrc-mode\SpecialChar ~
20976 Toggles Sdcdbsrc mode (turns it off)
20991 sdcdb-finish-from-src\SpecialChar ~
20999 SDCDB finish command
21014 sdcdb-break\SpecialChar ~
21032 Set break for line with point
21047 sdcdbsrc-mode\SpecialChar ~
21063 Toggle Sdcdbsrc mode
21078 sdcdbsrc-srcmode\SpecialChar ~
21101 Here are a few guidelines that will help the compiler generate more efficient
21102 code, some of the tips are specific to this compiler others are generally
21103 good programming practice.
21106 Use the smallest data type to represent your data-value.
21107 If it is known in advance that the value is going to be less than 256 then
21108 use an 'unsigned char' instead of a 'short' or 'int'.
21109 Please note, that ANSI C requires both signed and unsigned chars to be
21110 promoted to 'signed int' before doing any operation.
21112 \begin_inset LatexCommand \index{type promotion}
21116 can be omitted, if the result is the same.
21117 The effect of the promotion rules together with the sign-extension is often
21124 unsigned char uc = 0xfe;
21126 if (uc * uc < 0) /* this is true! */
21145 (int) uc * (int) uc = (int) 0xfe * (int) 0xfe = (int) 0xfc04 = -1024
21155 (unsigned char) -12 / (signed char) -3 = ...
21158 No, the result is not 4:
21163 (int) (unsigned char) -12 / (int) (signed char) -3 =
21165 (int) (unsigned char) 0xf4 / (int) (signed char) 0xfd =
21167 (int) 0x00f4 / (int) 0xfffd =
21169 (int) 0x00f4 / (int) 0xfffd =
21171 (int) 244 / (int) -3 =
21173 (int) -81 = (int) 0xffaf;
21176 Don't complain, that gcc gives you a different result.
21177 gcc uses 32 bit ints, while SDCC uses 16 bit ints.
21178 Therefore the results are different.
21181 \begin_inset Quotes sld
21185 \begin_inset Quotes srd
21191 If well-defined overflow characteristics are important and negative values
21192 are not, or if you want to steer clear of sign-extension problems when
21193 manipulating bits or bytes, use one of the corresponding unsigned types.
21194 (Beware when mixing signed and unsigned values in expressions, though.)
21196 Although character types (especially unsigned char) can be used as "tiny"
21197 integers, doing so is sometimes more trouble than it's worth, due to unpredicta
21198 ble sign extension and increased code size.
21202 Use unsigned when it is known in advance that the value is not going to
21204 This helps especially if you are doing division or multiplication, bit-shifting
21205 or are using an array index.
21208 NEVER jump into a LOOP.
21211 Declare the variables to be local
21212 \begin_inset LatexCommand \index{local variables}
21216 whenever possible, especially loop control variables (induction).
21219 Since the compiler does not always do implicit integral promotion, the programme
21220 r should do an explicit cast when integral promotion is required.
21223 Reducing the size of division, multiplication & modulus operations can reduce
21224 code size substantially.
21225 Take the following code for example.
21231 foobar(unsigned int p1, unsigned char ch)
21239 unsigned char ch1 = p1 % ch ;
21250 For the modulus operation the variable ch will be promoted to unsigned int
21251 first then the modulus operation will be performed (this will lead to a
21252 call to support routine _moduint()), and the result will be casted to a
21254 If the code is changed to
21259 foobar(unsigned int p1, unsigned char ch)
21267 unsigned char ch1 = (unsigned char)p1 % ch ;
21278 It would substantially reduce the code generated (future versions of the
21279 compiler will be smart enough to detect such optimization opportunities).
21283 Have a look at the assembly listing to get a
21284 \begin_inset Quotes sld
21288 \begin_inset Quotes srd
21291 for the code generation.
21295 \begin_inset LatexCommand \index{Tools}
21299 included in the distribution
21303 \begin_inset Tabular
21304 <lyxtabular version="3" rows="12" columns="3">
21306 <column alignment="center" valignment="top" leftline="true" width="0pt">
21307 <column alignment="center" valignment="top" leftline="true" width="0pt">
21308 <column alignment="left" valignment="top" leftline="true" rightline="true" width="0pt">
21309 <row topline="true" bottomline="true">
21310 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
21318 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
21326 <cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
21335 <row topline="true">
21336 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
21344 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
21349 Simulator for various architectures
21352 <cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
21361 <row topline="true">
21362 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
21370 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
21375 header file conversion
21378 <cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
21383 sdcc/support/scripts
21387 <row topline="true">
21388 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
21396 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
21401 header file conversion
21404 <cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
21409 sdcc/support/scripts
21413 <row topline="true">
21414 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
21422 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
21430 <cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
21448 <row topline="true">
21449 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
21457 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
21465 <cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
21483 <row topline="true">
21484 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
21492 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
21500 <cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
21518 <row topline="true">
21519 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
21527 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
21535 <cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
21553 <row topline="true">
21554 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
21562 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
21570 <cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
21588 <row topline="true">
21589 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
21597 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
21605 <cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
21623 <row topline="true">
21624 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
21632 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
21640 <cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
21658 <row topline="true" bottomline="true">
21659 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
21667 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
21675 <cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
21703 \begin_inset LatexCommand \index{Documentation}
21707 included in the distribution
21711 \begin_inset Tabular
21712 <lyxtabular version="3" rows="10" columns="2">
21714 <column alignment="left" valignment="top" leftline="true" width="0">
21715 <column alignment="left" valignment="top" leftline="true" rightline="true" width="0pt">
21716 <row topline="true" bottomline="true">
21717 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
21725 <cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
21730 Where to get / filename
21734 <row topline="true">
21735 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
21740 SDCC Compiler User Guide
21743 <cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
21748 You're reading it right now
21752 <row topline="true">
21753 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
21761 <cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
21770 <row topline="true">
21771 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
21777 \begin_inset LatexCommand \index{asXXXX (as-gbz80, as-hc08, asx8051, as-z80)}
21782 \begin_inset LatexCommand \index{Assembler documentation}
21786 Assemblers and ASLINK
21787 \begin_inset LatexCommand \index{aslink}
21792 \begin_inset LatexCommand \index{Linker documentation}
21799 <cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
21804 sdcc/as/doc/asxhtm.html
21808 <row topline="true">
21809 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
21814 SDCC regression test
21815 \begin_inset LatexCommand \index{Regression test}
21822 <cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
21827 sdcc/doc/test_suite_spec.pdf
21831 <row topline="true">
21832 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
21840 <cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
21849 <row topline="true">
21850 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
21855 Notes on debugging with sdcdb
21856 \begin_inset LatexCommand \index{sdcdb (debugger)}
21863 <cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
21868 sdcc/debugger/README
21872 <row topline="true">
21873 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
21878 Software simulator for microcontrollers
21881 <cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
21908 <row topline="true">
21909 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
21914 Temporary notes on the pic16
21915 \begin_inset LatexCommand \index{PIC16}
21922 <cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
21927 sdcc/src/pic16/NOTES
21931 <row topline="true" bottomline="true">
21932 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
21937 SDCC internal documentation (debugging file format)
21940 <cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
21976 Related open source tools
21977 \begin_inset LatexCommand \index{Related tools}
21985 \begin_inset Tabular
21986 <lyxtabular version="3" rows="11" columns="3">
21988 <column alignment="center" valignment="top" leftline="true" width="0pt">
21989 <column alignment="block" valignment="top" leftline="true" width="30line%">
21990 <column alignment="left" valignment="top" leftline="true" rightline="true" width="0pt">
21991 <row topline="true" bottomline="true">
21992 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
22000 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
22008 <cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
22017 <row topline="true">
22018 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
22024 \begin_inset LatexCommand \index{gpsim (pic simulator)}
22031 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
22039 <cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
22045 \begin_inset LatexCommand \url{http://www.dattalo.com/gnupic/gpsim.html}
22053 <row topline="true">
22054 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
22060 \begin_inset LatexCommand \index{gputils (pic tools)}
22067 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
22075 <cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
22081 \begin_inset LatexCommand \url{http://sourceforge.net/projects/gputils}
22089 <row topline="true">
22090 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
22098 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
22106 <cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
22112 \begin_inset LatexCommand \url{http://freshmeat.net/projects/flp5/}
22120 <row topline="true">
22121 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
22127 \begin_inset LatexCommand \index{indent (source formatting tool)}
22134 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
22139 Formats C source - Master of the white spaces
22142 <cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
22148 \begin_inset LatexCommand \url{http://directory.fsf.org/GNU/indent.html}
22156 <row topline="true">
22157 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
22163 \begin_inset LatexCommand \index{srecord (bin, hex, ... tool)}
22170 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
22175 Object file conversion, checksumming, ...
22178 <cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
22184 \begin_inset LatexCommand \url{http://sourceforge.net/projects/srecord}
22192 <row topline="true">
22193 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
22199 \begin_inset LatexCommand \index{objdump (tool)}
22206 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
22211 Object file conversion, ...
22214 <cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
22219 Part of binutils (should be there anyway)
22223 <row topline="true">
22224 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
22230 \begin_inset LatexCommand \index{doxygen (source documentation tool)}
22237 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
22242 Source code documentation system
22245 <cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
22251 \begin_inset LatexCommand \url{http://www.doxygen.org}
22259 <row topline="true">
22260 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
22268 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
22273 IDE (has anyone tried integrating SDCC & sdcdb? Unix only)
22276 <cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
22282 \begin_inset LatexCommand \url{http://www.kdevelop.org}
22290 <row topline="true">
22291 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
22297 \begin_inset LatexCommand \index{splint (syntax checking tool)}
22304 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
22309 Statically checks c sources (see
22310 \begin_inset LatexCommand \ref{lyx:more-pedantic-SPLINT}
22317 <cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
22323 \begin_inset LatexCommand \url{http://www.splint.org}
22331 <row topline="true" bottomline="true">
22332 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
22338 \begin_inset LatexCommand \index{ddd (debugger)}
22345 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
22350 Debugger, serves nicely as GUI to sdcdb
22351 \begin_inset LatexCommand \index{sdcdb (debugger)}
22358 <cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
22364 \begin_inset LatexCommand \url{http://www.gnu.org/software/ddd/}
22381 Related documentation / recommended reading
22385 \begin_inset Tabular
22386 <lyxtabular version="3" rows="6" columns="3">
22388 <column alignment="center" valignment="top" leftline="true" width="0pt">
22389 <column alignment="block" valignment="top" leftline="true" width="30line%">
22390 <column alignment="center" valignment="top" leftline="true" rightline="true" width="0pt">
22391 <row topline="true" bottomline="true">
22392 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
22400 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
22408 <cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
22417 <row topline="true">
22418 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
22435 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
22441 \begin_inset LatexCommand \index{C Reference card}
22448 <cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
22454 \begin_inset LatexCommand \url{http://refcards.com/refcards/c/index.html}
22462 <row topline="true">
22463 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
22471 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
22479 <cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
22485 \begin_inset LatexCommand \url{http://www.eskimo.com/~scs/C-faq/top.html}
22493 <row topline="true">
22494 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
22501 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
22506 Latest datasheet of the target CPU
22509 <cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
22518 <row topline="true">
22519 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
22526 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
22531 Revision history of datasheet
22534 <cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
22543 <row topline="true" bottomline="true">
22544 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
22554 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
22559 Advanced Compiler Design and Implementation
22562 <cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
22567 bookstore (very dedicated, probably read other books first)
22583 Some questions answered, some pointers given - it might be time to in turn
22591 can you solve your project with the selected microcontroller? Would you
22592 find out early or rather late that your target is too small/slow/whatever?
22593 Can you switch to a slightly better device if it doesn't fit?
22596 should you solve the problem with an 8 bit CPU? Or would a 16/32 bit CPU
22597 and/or another programming language be more adequate? Would an operating
22598 system on the target device help?
22601 if you solved the problem, will the marketing department be happy?
22604 if the marketing department is happy, will customers be happy?
22607 if you're the project manager, marketing department and maybe even the customer
22608 in one person, have you tried to see the project from the outside?
22611 is the project done if you think it is done? Or is just that other interface/pro
22612 tocol/feature/configuration/option missing? How about website, manual(s),
22613 internationali(z|s)ation, packaging, labels, 2nd source for components,
22614 electromagnetic compatability/interference, documentation for production,
22615 production test software, update mechanism, patent issues?
22618 is your project adequately positioned in that magic triangle: fame, fortune,
22622 Maybe not all answers to these questions are known and some answers may
22627 , nevertheless knowing these questions may help you to avoid burnout
22633 burnout is bad for electronic devices, programmers and motorcycle tyres
22637 Chances are you didn't want to hear some of them...
22641 \begin_inset LatexCommand \index{Support}
22648 SDCC has grown to be a large project.
22649 The compiler alone (without the preprocessor, assembler and linker) is
22650 well over 100,000 lines of code (blank stripped).
22651 The open source nature of this project is a key to its continued growth
22653 You gain the benefit and support of many active software developers and
22655 Is SDCC perfect? No, that's why we need your help.
22656 The developers take pride in fixing reported bugs.
22657 You can help by reporting the bugs and helping other SDCC users.
22658 There are lots of ways to contribute, and we encourage you to take part
22659 in making SDCC a great software package.
22663 The SDCC project is hosted on the SDCC sourceforge site at
22664 \begin_inset LatexCommand \htmlurl{http://sourceforge.net/projects/sdcc}
22669 You'll find the complete set of mailing lists
22670 \begin_inset LatexCommand \index{Mailing list(s)}
22674 , forums, bug reporting system, patch submission
22675 \begin_inset LatexCommand \index{Patch submission}
22680 \begin_inset LatexCommand \index{download}
22684 area and cvs code repository
22685 \begin_inset LatexCommand \index{cvs code repository}
22693 \begin_inset LatexCommand \index{Bug reporting}
22698 \begin_inset LatexCommand \index{Reporting bugs}
22705 The recommended way of reporting bugs is using the infrastructure of the
22707 You can follow the status of bug reports there and have an overview about
22711 Bug reports are automatically forwarded to the developer mailing list and
22712 will be fixed ASAP.
22713 When reporting a bug, it is very useful to include a small test program
22714 (the smaller the better) which reproduces the problem.
22715 If you can isolate the problem by looking at the generated assembly code,
22716 this can be very helpful.
22717 Compiling your program with the -
22728 \begin_inset LatexCommand \index{-\/-dumpall}
22732 option can sometimes be useful in locating optimization problems.
22733 When reporting a bug please maker sure you:
22736 Attach the code you are compiling with SDCC.
22740 Specify the exact command you use to run SDCC, or attach your Makefile.
22744 Specify the SDCC version (type "
22750 "), your platform, and operating system.
22754 Provide an exact copy of any error message or incorrect output.
22758 Put something meaningful in the subject of your message.
22761 Please attempt to include these 5 important parts, as applicable, in all
22762 requests for support or when reporting any problems or bugs with SDCC.
22763 Though this will make your message lengthy, it will greatly improve your
22764 chance that SDCC users and developers will be able to help you.
22765 Some SDCC developers are frustrated by bug reports without code provided
22766 that they can use to reproduce and ultimately fix the problem, so please
22767 be sure to provide sample code if you are reporting a bug!
22770 Please have a short check that you are using a recent version of SDCC and
22771 the bug is not yet known.
22772 This is the link for reporting bugs:
22773 \begin_inset LatexCommand \htmlurl{http://sourceforge.net/tracker/?group_id=599&atid=100599}
22780 Requesting Features
22781 \begin_inset LatexCommand \label{sub:Requesting-Features}
22786 \begin_inset LatexCommand \index{Feature request}
22791 \begin_inset LatexCommand \index{Requesting features}
22798 Like bug reports feature requests are forwarded to the developer mailing
22800 This is the link for requesting features:
22801 \begin_inset LatexCommand \htmlurl{http://sourceforge.net/tracker/?group_id=599&atid=350599}
22811 Like bug reports contributed patches are forwarded to the developer mailing
22813 This is the link for submitting patches
22814 \begin_inset LatexCommand \index{Patch submission}
22819 \begin_inset LatexCommand \url{http://sourceforge.net/tracker/?group_id=599&atid=300599}
22826 You need to specify some parameters to the
22830 command for the patches to be useful.
22831 If you modified more than one file a patch created f.e.
22836 \begin_inset Quotes sld
22839 diff -Naur unmodified_directory modified_directory >my_changes.patch
22840 \begin_inset Quotes srd
22846 will be fine, otherwise
22850 \begin_inset Quotes sld
22853 diff -u sourcefile.c.orig sourcefile.c >my_changes.patch
22854 \begin_inset Quotes srd
22867 These links should take you directly to the
22868 \begin_inset LatexCommand \url[Mailing lists]{http://sourceforge.net/mail/?group_id=599}
22878 Traffic on sdcc-devel and sdcc-user is about 100 mails/month each not counting
22879 automated messages (mid 2003)
22883 \begin_inset LatexCommand \url[Forums]{http://sourceforge.net/forum/?group_id=599}
22888 \begin_inset LatexCommand \index{Mailing list(s)}
22892 and forums are archived and searchable so if you are lucky someone already
22893 had a similar problem.
22894 While mails to the lists themselves are delivered promptly their web front
22895 end on sourceforge sometimes shows a severe time lag (up to several weeks),
22896 if you're seriously using SDCC please consider subscribing to the lists.
22902 You can follow the status of the cvs version
22903 \begin_inset LatexCommand \index{version}
22907 of SDCC by watching the Changelog
22908 \begin_inset LatexCommand \index{Changelog}
22912 in the cvs-repository
22917 \begin_inset LatexCommand \htmlurl{http://cvs.sf.net/cgi-bin/viewcvs.cgi/*checkout*/sdcc/sdcc/ChangeLog?rev=HEAD&content-type=text/plain}
22925 \begin_inset LatexCommand \index{Release policy}
22932 Historically there often were long delays between official releases and
22933 the sourceforge download area tends to get not updated at all.
22934 Excuses in the past might have referred to problems with live range analysis,
22935 but as this was fixed a while ago, the current problem is that another
22936 excuse has to be found.
22937 Kidding aside, we have to get better there! On the other hand there are
22938 daily snapshots available at
22939 \begin_inset LatexCommand \htmlurl[snap]{http://sdcc.sourceforge.net/snap.php}
22943 , and you can always build the very last version (hopefully with many bugs
22944 fixed, and features added) from the source code available at
22945 \begin_inset LatexCommand \htmlurl[Source]{http://sdcc.sourceforge.net/snap.php#Source}
22953 \begin_inset LatexCommand \index{Examples}
22960 You'll find some small examples in the directory
22962 sdcc/device/examples/.
22965 More examples and libraries are available at
22967 The SDCC Open Knowledge Resource
22968 \begin_inset LatexCommand \url{http://sdccokr.dl9sec.de/}
22975 \begin_inset LatexCommand \url{http://www.pjrc.com/tech/8051/}
22982 I did insert a reference to Paul's web site here although it seems rather
22983 dedicated to a specific 8032 board (I think it's okay because it f.e.
22984 shows LCD/Harddisc interface and has a free 8051 monitor.
22985 Independent 8032 board vendors face hard competition of heavily subsidized
22986 development boards anyway).
22989 Maybe we should include some links to real world applications.
22990 Preferably pointer to pointers (one for each architecture) so this stays
22995 \begin_inset LatexCommand \index{Quality control}
23002 The compiler is passed through nightly compile and build checks.
23008 \begin_inset LatexCommand \index{Regression test}
23012 check that SDCC itself compiles flawlessly on several platforms and checks
23013 the quality of the code generated by SDCC by running the code through simulator
23015 There is a separate document
23018 \begin_inset LatexCommand \index{Test suite}
23027 You'll find the test code in the directory
23029 sdcc/support/regression
23032 You can run these tests manually by running
23036 in this directory (or f.e.
23041 \begin_inset Quotes sld
23045 \begin_inset Quotes srd
23051 if you don't want to run the complete tests).
23052 The test code might also be interesting if you want to look for examples
23053 \begin_inset LatexCommand \index{Examples}
23057 checking corner cases of SDCC or if you plan to submit patches
23058 \begin_inset LatexCommand \index{Patch submission}
23065 The pic port uses a different set of regression tests, you'll find them
23068 sdcc/src/regression
23073 SDCC Technical Data
23077 \begin_inset LatexCommand \index{Optimizations}
23084 SDCC performs a host of standard optimizations in addition to some MCU specific
23089 Sub-expression Elimination
23090 \begin_inset LatexCommand \index{Subexpression elimination}
23097 The compiler does local and
23123 will be translated to
23135 Some subexpressions are not as obvious as the above example, e.g.:
23145 In this case the address arithmetic a->b[i] will be computed only once;
23146 the equivalent code in C would be.
23158 The compiler will try to keep these temporary variables in registers.
23161 Dead-Code Elimination
23162 \begin_inset LatexCommand \index{Dead-code elimination}
23183 i = 1; \SpecialChar ~
23192 global = 1;\SpecialChar ~
23205 global = 3;\SpecialChar ~
23230 \begin_inset LatexCommand \index{Copy propagation}
23286 Note: the dead stores created by this copy propagation will be eliminated
23287 by dead-code elimination.
23291 \begin_inset LatexCommand \index{Loop optimization}
23296 \begin_inset LatexCommand \label{sub:Loop-Optimizations}
23303 Two types of loop optimizations are done by SDCC
23311 of loop induction variables.
23312 In addition to the strength reduction the optimizer marks the induction
23313 variables and the register allocator tries to keep the induction variables
23314 in registers for the duration of the loop.
23315 Because of this preference of the register allocator
23316 \begin_inset LatexCommand \index{Register allocation}
23320 , loop induction optimization causes an increase in register pressure, which
23321 may cause unwanted spilling of other temporary variables into the stack
23322 \begin_inset LatexCommand \index{stack}
23327 The compiler will generate a warning message when it is forced to allocate
23328 extra space either on the stack or data space.
23329 If this extra space allocation is undesirable then induction optimization
23330 can be eliminated either for the entire source file (with -
23340 -noinduction option) or for a given function only using #pragma\SpecialChar ~
23342 \begin_inset LatexCommand \index{\#pragma noinduction}
23355 for (i = 0 ; i < 100 ; i ++)
23371 for (i = 0; i < 100; i++)
23380 As mentioned previously some loop invariants are not as apparent, all static
23381 address computations are also moved out of the loop.
23386 \begin_inset LatexCommand \index{Strength reduction}
23390 , this optimization substitutes an expression by a cheaper expression:
23395 for (i=0;i < 100; i++)
23413 for (i=0;i< 100;i++) {
23419 ar[itemp1] = itemp2;
23436 The more expensive multiplication
23437 \begin_inset LatexCommand \index{Multiplication}
23441 is changed to a less expensive addition.
23445 \begin_inset LatexCommand \index{Loop reversing}
23452 This optimization is done to reduce the overhead of checking loop boundaries
23453 for every iteration.
23454 Some simple loops can be reversed and implemented using a
23455 \begin_inset Quotes eld
23458 decrement and jump if not zero
23459 \begin_inset Quotes erd
23463 SDCC checks for the following criterion to determine if a loop is reversible
23464 (note: more sophisticated compilers use data-dependency analysis to make
23465 this determination, SDCC uses a more simple minded analysis).
23468 The 'for' loop is of the form
23474 for(<symbol> = <expression>; <sym> [< | <=] <expression>; [<sym>++ | <sym>
23484 The <for body> does not contain
23485 \begin_inset Quotes eld
23489 \begin_inset Quotes erd
23493 \begin_inset Quotes erd
23499 All goto's are contained within the loop.
23502 No function calls within the loop.
23505 The loop control variable <sym> is not assigned any value within the loop
23508 The loop control variable does NOT participate in any arithmetic operation
23512 There are NO switch statements in the loop.
23515 Algebraic Simplifications
23518 SDCC does numerous algebraic simplifications, the following is a small sub-set
23519 of these optimizations.
23524 i = j + 0;\SpecialChar ~
23528 /* changed to: */\SpecialChar ~
23534 i /= 2;\SpecialChar ~
23541 /* changed to: */\SpecialChar ~
23547 i = j - j;\SpecialChar ~
23551 /* changed to: */\SpecialChar ~
23557 i = j / 1;\SpecialChar ~
23561 /* changed to: */\SpecialChar ~
23568 Note the subexpressions
23569 \begin_inset LatexCommand \index{Subexpression}
23573 given above are generally introduced by macro expansions or as a result
23574 of copy/constant propagation.
23577 'switch' Statements
23578 \begin_inset LatexCommand \label{sub:'switch'-Statements}
23583 \begin_inset LatexCommand \index{switch statement}
23590 SDCC can optimize switch statements to jump tables
23591 \begin_inset LatexCommand \index{jump tables}
23596 It makes the decision based on an estimate of the generated code size.
23597 SDCC is quite liberal in the requirements for jump table generation:
23600 The labels need not be in order, and the starting number need not be one
23601 or zero, the case labels are in numerical sequence or not too many case
23602 labels are missing.
23608 switch(i) {\SpecialChar ~
23639 case 4: ...\SpecialChar ~
23671 case 5: ...\SpecialChar ~
23703 case 3: ...\SpecialChar ~
23734 case 6: ...\SpecialChar ~
23766 case 7: ...\SpecialChar ~
23798 case 8: ...\SpecialChar ~
23830 case 9: ...\SpecialChar ~
23862 case 10: ...\SpecialChar ~
23893 case 11: ...\SpecialChar ~
23960 Both the above switch statements will be implemented using a jump-table.
23961 The example to the right side is slightly more efficient as the check for
23962 the lower boundary of the jump-table is not needed.
23966 The number of case labels is not larger than supported by the target architectur
23970 If the case labels are not in numerical sequence ('gaps' between cases)
23971 SDCC checks whether a jump table with additionally inserted dummy cases
23972 is still attractive.
23976 If the starting number is not zero and a check for the lower boundary of
23977 the jump-table can thus be eliminated SDCC might insert dummy cases 0,
23982 Switch statements which have large gaps in the numeric sequence or those
23983 that have too many case labels can be split into more than one switch statement
23984 for efficient code generation, e.g.:
24064 If the above switch statement is broken down into two switch statements
24154 then both the switch statements will be implemented using jump-tables whereas
24155 the unmodified switch statement will not be.
24158 There might be reasons which SDCC cannot know about to either favour or
24159 not favour jump tables.
24160 If the target system has to be as quick for the last switch case as for
24161 the first (pro jump table), or if the switch argument is known to be zero
24162 in the majority of the cases (contra jump table).
24165 The pragma nojtbound
24166 \begin_inset LatexCommand \index{\#pragma nojtbound}
24170 can be used to turn off checking the
24183 It has no effect if a default label is supplied.
24184 Use of this pragma is dangerous: if the switch
24185 \begin_inset LatexCommand \index{switch statement}
24189 argument is not matched by a case statement the processor will happily
24193 Bit-shifting Operations
24194 \begin_inset LatexCommand \index{Bit shifting}
24201 Bit shifting is one of the most frequently used operation in embedded programmin
24203 SDCC tries to implement bit-shift operations in the most efficient way
24219 generates the following code:
24236 In general SDCC will never setup a loop if the shift count is known.
24279 \begin_inset LatexCommand \index{Bit rotation}
24286 A special case of the bit-shift operation is bit rotation
24287 \begin_inset LatexCommand \index{rotating bits}
24291 , SDCC recognizes the following expression to be a left bit-rotation:
24301 char i;\SpecialChar ~
24312 /* unsigned is needed for rotation */
24317 i = ((i << 1) | (i >> 7));
24326 will generate the following code:
24345 SDCC uses pattern matching on the parse tree to determine this operation.Variatio
24346 ns of this case will also be recognized as bit-rotation, i.e.:
24351 i = ((i >> 7) | (i << 1)); /* left-bit rotation */
24354 Nibble and Byte Swapping
24357 Other special cases of the bit-shift operations are nibble or byte swapping
24358 \begin_inset LatexCommand \index{swapping nibbles/bytes}
24362 , SDCC recognizes the following expressions:
24385 i = ((i << 4) | (i >> 4));
24391 j = ((j << 8) | (j >> 8));
24394 and generates a swap instruction for the nibble swapping
24395 \begin_inset LatexCommand \index{Nibble swapping}
24399 or move instructions for the byte swapping
24400 \begin_inset LatexCommand \index{Byte swapping}
24406 \begin_inset Quotes sld
24410 \begin_inset Quotes srd
24413 example can be used to convert from little to big-endian or vice versa.
24414 If you want to change the endianness of a
24418 integer you have to cast to
24425 Note that SDCC stores numbers in little-endian
24431 Usually 8-bit processors don't care much about endianness.
24432 This is not the case for the standard 8051 which only has an instruction
24438 \begin_inset LatexCommand \index{DPTR}
24446 so little-endian is the more efficient byte order.
24450 \begin_inset LatexCommand \index{little-endian}
24455 \begin_inset LatexCommand \index{Endianness}
24460 lowest order first).
24464 \begin_inset LatexCommand \index{Highest Order Bit}
24471 It is frequently required to obtain the highest order bit of an integral
24472 type (long, int, short or char types).
24473 SDCC recognizes the following expression to yield the highest order bit
24474 and generates optimized code for it, e.g.:
24496 hob = (gint >> 15) & 1;
24506 will generate the following code:
24539 000A E5*01\SpecialChar ~
24566 000C 23\SpecialChar ~
24597 000D 54 01\SpecialChar ~
24624 000F F5*02\SpecialChar ~
24652 Variations of this case however will
24657 It is a standard C expression, so I heartily recommend this be the only
24658 way to get the highest order bit, (it is portable).
24659 Of course it will be recognized even if it is embedded in other expressions,
24665 xyz = gint + ((gint >> 15) & 1);
24668 will still be recognized.
24672 \begin_inset LatexCommand \label{sub:Peephole-Optimizer}
24677 \begin_inset LatexCommand \index{Peephole optimizer}
24684 The compiler uses a rule based, pattern matching and re-writing mechanism
24685 for peep-hole optimization.
24690 a peep-hole optimizer by Christopher W.
24691 Fraser (cwfraser\SpecialChar ~
24694 A default set of rules are compiled into the compiler, additional rules
24695 may be added with the
24708 \begin_inset LatexCommand \index{-\/-peep-file}
24715 The rule language is best illustrated with examples.
24739 The above rule will change the following assembly
24740 \begin_inset LatexCommand \index{Assembler routines}
24762 Note: All occurrences of a
24766 (pattern variable) must denote the same string.
24767 With the above rule, the assembly sequence:
24777 will remain unmodified.
24781 Other special case optimizations may be added by the user (via
24797 some variants of the 8051 MCU
24798 \begin_inset LatexCommand \index{MCS51 variants}
24811 The following two rules will change all
24830 replace { lcall %1 } by { acall %1 }
24832 replace { ljmp %1 } by { ajmp %1 }
24837 inline-assembler code
24839 is also passed through the peep hole optimizer, thus the peephole optimizer
24840 can also be used as an assembly level macro expander.
24841 The rules themselves are MCU dependent whereas the rule language infra-structur
24842 e is MCU independent.
24843 Peephole optimization rules for other MCU can be easily programmed using
24848 The syntax for a rule is as follows:
24853 rule := replace [ restart ] '{' <assembly sequence> '
24891 <assembly sequence> '
24909 '}' [if <functionName> ] '
24914 <assembly sequence> := assembly instruction (each instruction including
24915 labels must be on a separate line).
24919 The optimizer will apply to the rules one by one from the top in the sequence
24920 of their appearance, it will terminate when all rules are exhausted.
24921 If the 'restart' option is specified, then the optimizer will start matching
24922 the rules again from the top, this option for a rule is expensive (performance)
24923 , it is intended to be used in situations where a transformation will trigger
24924 the same rule again.
24925 An example of this (not a good one, it has side effects) is the following
24948 Note that the replace pattern cannot be a blank, but can be a comment line.
24949 Without the 'restart' option only the innermost 'pop' 'push' pair would
24950 be eliminated, i.e.:
24980 the restart option the rule will be applied again to the resulting code
24981 and then all the pop-push pairs will be eliminated to yield:
24991 A conditional function can be attached to a rule.
24992 Attaching rules are somewhat more involved, let me illustrate this with
25019 The optimizer does a look-up of a function name table defined in function
25024 in the source file SDCCpeeph.c, with the name
25029 If it finds a corresponding entry the function is called.
25030 Note there can be no parameters specified for these functions, in this
25035 is crucial, since the function
25039 expects to find the label in that particular variable (the hash table containin
25040 g the variable bindings is passed as a parameter).
25041 If you want to code more such functions, take a close look at the function
25042 labelInRange and the calling mechanism in source file SDCCpeeph.c.
25043 Currently implemented are
25045 labelInRange, labelRefCount, labelIsReturnOnly, operandsNotSame, xramMovcOption,
25046 24bitMode, portIsDS390, 24bitModeAndPortDS390
25055 I know this whole thing is a little kludgey, but maybe some day we will
25056 have some better means.
25057 If you are looking at this file, you will see the default rules that are
25058 compiled into the compiler, you can add your own rules in the default set
25059 there if you get tired of specifying the -
25073 \begin_inset LatexCommand \index{ANSI-compliance}
25078 \begin_inset LatexCommand \label{sub:ANSI-Compliance}
25085 Deviations from the compliance:
25088 functions are not reentrant
25089 \begin_inset LatexCommand \index{reentrant}
25093 unless explicitly declared as such or the
25106 \begin_inset LatexCommand \index{-\/-stack-auto}
25112 command line option is specified.
25115 structures and unions cannot be assigned values directly, cannot be passed
25116 as function parameters or assigned to each other and cannot be a return
25117 value from a function, e.g.:
25143 s1 = s2 ; /* is invalid in SDCC although allowed in ANSI */
25154 struct s foo1 (struct s parms) /* invalid in SDCC although allowed in ANSI
25176 return rets;/* is invalid in SDCC although allowed in ANSI */
25183 \begin_inset LatexCommand \index{long long (not supported)}
25188 \begin_inset LatexCommand \index{int (64 bit) (not supported)}
25196 \begin_inset LatexCommand \index{double (not supported)}
25200 ' precision floating point
25201 \begin_inset LatexCommand \index{Floating point support}
25208 No support for setjmp
25209 \begin_inset LatexCommand \index{setjmp (not supported)}
25214 \begin_inset LatexCommand \index{longjmp (not supported)}
25222 \begin_inset LatexCommand \index{K\&R style}
25226 function declarations are NOT allowed.
25232 foo(i,j) /* this old style of function declarations */
25234 int i,j; /* are valid in ANSI but not valid in SDCC */
25249 Certain words that are valid identifiers in the standard may be reserved
25250 words in SDCC unless the
25263 \begin_inset LatexCommand \index{-\/-std-c89}
25278 \begin_inset LatexCommand \index{-\/-std-c99}
25284 command line options are used.
25285 These may include (depending on the selected processor): 'at', 'banked',
25286 'bit', 'code', 'critical', 'data', 'eeprom', 'far', 'flash', 'idata', 'interrup
25287 t', 'near', 'nonbanked', 'pdata', 'reentrant', 'sbit', 'sfr', 'shadowregs',
25288 'sram', 'using', 'wparam', 'xdata', '_overlay', '_asm', '_endasm', and
25290 Compliant equivalents of these keywords are always available in a form
25291 that begin with two underscores
25292 \begin_inset LatexCommand \index{\_\_ (prefix for extended keywords)}
25297 '__data' instead of 'data'.
25300 Cyclomatic Complexity
25301 \begin_inset LatexCommand \index{Cyclomatic complexity}
25308 Cyclomatic complexity of a function is defined as the number of independent
25309 paths the program can take during execution of the function.
25310 This is an important number since it defines the number test cases you
25311 have to generate to validate the function.
25312 The accepted industry standard for complexity number is 10, if the cyclomatic
25313 complexity reported by SDCC exceeds 10 you should think about simplification
25314 of the function logic.
25315 Note that the complexity level is not related to the number of lines of
25316 code in a function.
25317 Large functions can have low complexity, and small functions can have large
25323 SDCC uses the following formula to compute the complexity:
25328 complexity = (number of edges in control flow graph) - (number of nodes
25329 in control flow graph) + 2;
25333 Having said that the industry standard is 10, you should be aware that in
25334 some cases it be may unavoidable to have a complexity level of less than
25336 For example if you have switch statement with more than 10 case labels,
25337 each case label adds one to the complexity level.
25338 The complexity level is by no means an absolute measure of the algorithmic
25339 complexity of the function, it does however provide a good starting point
25340 for which functions you might look at for further optimization.
25343 Retargetting for other Processors
25346 The issues for retargetting the compiler are far too numerous to be covered
25348 What follows is a brief description of each of the seven phases of the
25349 compiler and its MCU dependency.
25352 Parsing the source and building the annotated parse tree.
25353 This phase is largely MCU independent (except for the language extensions).
25354 Syntax & semantic checks are also done in this phase, along with some initial
25355 optimizations like back patching labels and the pattern matching optimizations
25356 like bit-rotation etc.
25359 The second phase involves generating an intermediate code which can be easy
25360 manipulated during the later phases.
25361 This phase is entirely MCU independent.
25362 The intermediate code generation assumes the target machine has unlimited
25363 number of registers, and designates them with the name iTemp.
25364 The compiler can be made to dump a human readable form of the code generated
25378 This phase does the bulk of the standard optimizations and is also MCU independe
25380 This phase can be broken down into several sub-phases:
25384 Break down intermediate code (iCode) into basic blocks.
25386 Do control flow & data flow analysis on the basic blocks.
25388 Do local common subexpression elimination, then global subexpression elimination
25390 Dead code elimination
25394 If loop optimizations caused any changes then do 'global subexpression eliminati
25395 on' and 'dead code elimination' again.
25398 This phase determines the live-ranges; by live range I mean those iTemp
25399 variables defined by the compiler that still survive after all the optimization
25401 Live range analysis
25402 \begin_inset LatexCommand \index{Live range analysis}
25406 is essential for register allocation, since these computation determines
25407 which of these iTemps will be assigned to registers, and for how long.
25410 Phase five is register allocation.
25411 There are two parts to this process.
25415 The first part I call 'register packing' (for lack of a better term).
25416 In this case several MCU specific expression folding is done to reduce
25421 The second part is more MCU independent and deals with allocating registers
25422 to the remaining live ranges.
25423 A lot of MCU specific code does creep into this phase because of the limited
25424 number of index registers available in the 8051.
25427 The Code generation phase is (unhappily), entirely MCU dependent and very
25428 little (if any at all) of this code can be reused for other MCU.
25429 However the scheme for allocating a homogenized assembler operand for each
25430 iCode operand may be reused.
25433 As mentioned in the optimization section the peep-hole optimizer is rule
25434 based system, which can reprogrammed for other MCUs.
25438 \begin_inset LatexCommand \index{Compiler internals}
25445 The anatomy of the compiler
25446 \begin_inset LatexCommand \label{sub:The-anatomy-of}
25455 This is an excerpt from an article published in Circuit Cellar Magazine
25461 It's a little outdated (the compiler is much more efficient now and user/develo
25462 per friendly), but pretty well exposes the guts of it all.
25468 The current version of SDCC can generate code for Intel 8051 and Z80 MCU.
25469 It is fairly easy to retarget for other 8-bit MCU.
25470 Here we take a look at some of the internals of the compiler.
25475 \begin_inset LatexCommand \index{Parsing}
25482 Parsing the input source file and creating an AST (Annotated Syntax Tree
25483 \begin_inset LatexCommand \index{Annotated syntax tree}
25488 This phase also involves propagating types (annotating each node of the
25489 parse tree with type information) and semantic analysis.
25490 There are some MCU specific parsing rules.
25491 For example the storage classes, the extended storage classes are MCU specific
25492 while there may be a xdata storage class for 8051 there is no such storage
25493 class for z80 or Atmel AVR.
25494 SDCC allows MCU specific storage class extensions, i.e.
25495 xdata will be treated as a storage class specifier when parsing 8051 C
25496 code but will be treated as a C identifier when parsing z80 or ATMEL AVR
25501 \begin_inset LatexCommand \index{iCode}
25508 Intermediate code generation.
25509 In this phase the AST is broken down into three-operand form (iCode).
25510 These three operand forms are represented as doubly linked lists.
25511 ICode is the term given to the intermediate form generated by the compiler.
25512 ICode example section shows some examples of iCode generated for some simple
25513 C source functions.
25517 \begin_inset LatexCommand \index{Optimizations}
25524 Bulk of the target independent optimizations is performed in this phase.
25525 The optimizations include constant propagation, common sub-expression eliminati
25526 on, loop invariant code movement, strength reduction of loop induction variables
25527 and dead-code elimination.
25530 Live range analysis
25531 \begin_inset LatexCommand \index{Live range analysis}
25538 During intermediate code generation phase, the compiler assumes the target
25539 machine has infinite number of registers and generates a lot of temporary
25541 The live range computation determines the lifetime of each of these compiler-ge
25542 nerated temporaries.
25543 A picture speaks a thousand words.
25544 ICode example sections show the live range annotations for each of the
25546 It is important to note here, each iCode is assigned a number in the order
25547 of its execution in the function.
25548 The live ranges are computed in terms of these numbers.
25549 The from number is the number of the iCode which first defines the operand
25550 and the to number signifies the iCode which uses this operand last.
25553 Register Allocation
25554 \begin_inset LatexCommand \index{Register allocation}
25561 The register allocation determines the type and number of registers needed
25563 In most MCUs only a few registers can be used for indirect addressing.
25564 In case of 8051 for example the registers R0 & R1 can be used to indirectly
25565 address the internal ram and DPTR to indirectly address the external ram.
25566 The compiler will try to allocate the appropriate register to pointer variables
25568 ICode example section shows the operands annotated with the registers assigned
25570 The compiler will try to keep operands in registers as much as possible;
25571 there are several schemes the compiler uses to do achieve this.
25572 When the compiler runs out of registers the compiler will check to see
25573 if there are any live operands which is not used or defined in the current
25574 basic block being processed, if there are any found then it will push that
25575 operand and use the registers in this block, the operand will then be popped
25576 at the end of the basic block.
25580 There are other MCU specific considerations in this phase.
25581 Some MCUs have an accumulator; very short-lived operands could be assigned
25582 to the accumulator instead of a general-purpose register.
25588 Figure II gives a table of iCode operations supported by the compiler.
25589 The code generation involves translating these operations into corresponding
25590 assembly code for the processor.
25591 This sounds overly simple but that is the essence of code generation.
25592 Some of the iCode operations are generated on a MCU specific manner for
25593 example, the z80 port does not use registers to pass parameters so the
25594 SEND and RECV iCode operations will not be generated, and it also does
25595 not support JUMPTABLES.
25602 <Where is Figure II?>
25605 In the original article Figure II was announced to be downloadable on
25610 Unfortunately it never seemed to have shown up there, so: where is Figure
25615 \begin_inset LatexCommand \index{iCode}
25622 This section shows some details of iCode.
25623 The example C code does not do anything useful; it is used as an example
25624 to illustrate the intermediate code generated by the compiler.
25636 /* This function does nothing useful.
25643 for the purpose of explaining iCode */
25646 short function (data int *x)
25654 short i=10; \SpecialChar ~
25656 /* dead initialization eliminated */
25661 short sum=10; /* dead initialization eliminated */
25674 while (*x) *x++ = *p++;
25688 /* compiler detects i,j to be induction variables */
25692 for (i = 0, j = 10 ; i < 10 ; i++, j
25718 mul += i * 3; \SpecialChar ~
25720 /* this multiplication remains */
25726 gint += j * 3;\SpecialChar ~
25728 /* this multiplication changed to addition */
25742 In addition to the operands each iCode contains information about the filename
25743 and line it corresponds to in the source file.
25744 The first field in the listing should be interpreted as follows:
25749 Filename(linenumber: iCode Execution sequence number : ICode hash table
25750 key : loop depth of the iCode).
25755 Then follows the human readable form of the ICode operation.
25756 Each operand of this triplet form can be of three basic types a) compiler
25757 generated temporary b) user defined variable c) a constant value.
25758 Note that local variables and parameters are replaced by compiler generated
25761 \begin_inset LatexCommand \index{Live range analysis}
25765 are computed only for temporaries (i.e.
25766 live ranges are not computed for global variables).
25768 \begin_inset LatexCommand \index{Register allocation}
25772 are allocated for temporaries only.
25773 Operands are formatted in the following manner:
25778 Operand Name [lr live-from : live-to ] { type information } [ registers
25784 As mentioned earlier the live ranges are computed in terms of the execution
25785 sequence number of the iCodes, for example
25787 the iTemp0 is live from (i.e.
25788 first defined in iCode with execution sequence number 3, and is last used
25789 in the iCode with sequence number 5).
25790 For induction variables such as iTemp21 the live range computation extends
25791 the lifetime from the start to the end of the loop.
25793 The register allocator used the live range information to allocate registers,
25794 the same registers may be used for different temporaries if their live
25795 ranges do not overlap, for example r0 is allocated to both iTemp6 and to
25796 iTemp17 since their live ranges do not overlap.
25797 In addition the allocator also takes into consideration the type and usage
25798 of a temporary, for example itemp6 is a pointer to near space and is used
25799 as to fetch data from (i.e.
25800 used in GET_VALUE_AT_ADDRESS) so it is allocated a pointer register (r0).
25801 Some short lived temporaries are allocated to special registers which have
25802 meaning to the code generator e.g.
25803 iTemp13 is allocated to a pseudo register CC which tells the back end that
25804 the temporary is used only for a conditional jump the code generation makes
25805 use of this information to optimize a compare and jump ICode.
25807 There are several loop optimizations
25808 \begin_inset LatexCommand \index{Loop optimization}
25812 performed by the compiler.
25813 It can detect induction variables iTemp21(i) and iTemp23(j).
25814 Also note the compiler does selective strength reduction
25815 \begin_inset LatexCommand \index{Strength reduction}
25820 the multiplication of an induction variable in line 18 (gint = j * 3) is
25821 changed to addition, a new temporary iTemp17 is allocated and assigned
25822 a initial value, a constant 3 is then added for each iteration of the loop.
25823 The compiler does not change the multiplication
25824 \begin_inset LatexCommand \index{Multiplication}
25828 in line 17 however since the processor does support an 8 * 8 bit multiplication.
25830 Note the dead code elimination
25831 \begin_inset LatexCommand \index{Dead-code elimination}
25835 optimization eliminated the dead assignments in line 7 & 8 to I and sum
25843 Sample.c (5:1:0:0) _entry($9) :
25848 Sample.c(5:2:1:0) proc _function [lr0:0]{function short}
25853 Sample.c(11:3:2:0) iTemp0 [lr3:5]{_near * int}[r2] = recv
25858 Sample.c(11:4:53:0) preHeaderLbl0($11) :
25863 Sample.c(11:5:55:0) iTemp6 [lr5:16]{_near * int}[r0] := iTemp0 [lr3:5]{_near
25869 Sample.c(11:6:5:1) _whilecontinue_0($1) :
25874 Sample.c(11:7:7:1) iTemp4 [lr7:8]{int}[r2 r3] = @[iTemp6 [lr5:16]{_near *
25880 Sample.c(11:8:8:1) if iTemp4 [lr7:8]{int}[r2 r3] == 0 goto _whilebreak_0($3)
25885 Sample.c(11:9:14:1) iTemp7 [lr9:13]{_far * int}[DPTR] := _p [lr0:0]{_far
25891 Sample.c(11:10:15:1) _p [lr0:0]{_far * int} = _p [lr0:0]{_far * int} + 0x2
25897 Sample.c(11:13:18:1) iTemp10 [lr13:14]{int}[r2 r3] = @[iTemp7 [lr9:13]{_far
25903 Sample.c(11:14:19:1) *(iTemp6 [lr5:16]{_near * int}[r0]) := iTemp10 [lr13:14]{int
25909 Sample.c(11:15:12:1) iTemp6 [lr5:16]{_near * int}[r0] = iTemp6 [lr5:16]{_near
25910 * int}[r0] + 0x2 {short}
25915 Sample.c(11:16:20:1) goto _whilecontinue_0($1)
25920 Sample.c(11:17:21:0)_whilebreak_0($3) :
25925 Sample.c(12:18:22:0) iTemp2 [lr18:40]{short}[r2] := 0x0 {short}
25930 Sample.c(13:19:23:0) iTemp11 [lr19:40]{short}[r3] := 0x0 {short}
25935 Sample.c(15:20:54:0)preHeaderLbl1($13) :
25940 Sample.c(15:21:56:0) iTemp21 [lr21:38]{short}[r4] := 0x0 {short}
25945 Sample.c(15:22:57:0) iTemp23 [lr22:38]{int}[r5 r6] := 0xa {int}
25950 Sample.c(15:23:58:0) iTemp17 [lr23:38]{int}[r7 r0] := 0x1e {int}
25955 Sample.c(15:24:26:1)_forcond_0($4) :
25960 Sample.c(15:25:27:1) iTemp13 [lr25:26]{char}[CC] = iTemp21 [lr21:38]{short}[r4]
25966 Sample.c(15:26:28:1) if iTemp13 [lr25:26]{char}[CC] == 0 goto _forbreak_0($7)
25971 Sample.c(16:27:31:1) iTemp2 [lr18:40]{short}[r2] = iTemp2 [lr18:40]{short}[r2]
25972 + ITemp21 [lr21:38]{short}[r4]
25977 Sample.c(17:29:33:1) iTemp15 [lr29:30]{short}[r1] = iTemp21 [lr21:38]{short}[r4]
25983 Sample.c(17:30:34:1) iTemp11 [lr19:40]{short}[r3] = iTemp11 [lr19:40]{short}[r3]
25984 + iTemp15 [lr29:30]{short}[r1]
25989 Sample.c(18:32:36:1:1) iTemp17 [lr23:38]{int}[r7 r0]= iTemp17 [lr23:38]{int}[r7
25995 Sample.c(18:33:37:1) _gint [lr0:0]{int} = _gint [lr0:0]{int} + iTemp17 [lr23:38]{
26001 Sample.c(15:36:42:1) iTemp21 [lr21:38]{short}[r4] = iTemp21 [lr21:38]{short}[r4]
26007 Sample.c(15:37:45:1) iTemp23 [lr22:38]{int}[r5 r6]= iTemp23 [lr22:38]{int}[r5
26013 Sample.c(19:38:47:1) goto _forcond_0($4)
26018 Sample.c(19:39:48:0)_forbreak_0($7) :
26023 Sample.c(20:40:49:0) iTemp24 [lr40:41]{short}[DPTR] = iTemp2 [lr18:40]{short}[r2]
26024 + ITemp11 [lr19:40]{short}[r3]
26029 Sample.c(20:41:50:0) ret iTemp24 [lr40:41]{short}
26034 Sample.c(20:42:51:0)_return($8) :
26039 Sample.c(20:43:52:0) eproc _function [lr0:0]{ ia0 re0 rm0}{function short}
26045 Finally the code generated for this function:
26086 ; ----------------------------------------------
26091 ; function function
26096 ; ----------------------------------------------
26106 ; iTemp0 [lr3:5]{_near * int}[r2] = recv
26118 ; iTemp6 [lr5:16]{_near * int}[r0] := iTemp0 [lr3:5]{_near * int}[r2]
26130 ;_whilecontinue_0($1) :
26140 ; iTemp4 [lr7:8]{int}[r2 r3] = @[iTemp6 [lr5:16]{_near * int}[r0]]
26145 ; if iTemp4 [lr7:8]{int}[r2 r3] == 0 goto _whilebreak_0($3)
26204 ; iTemp7 [lr9:13]{_far * int}[DPTR] := _p [lr0:0]{_far * int}
26223 ; _p [lr0:0]{_far * int} = _p [lr0:0]{_far * int} + 0x2 {short}
26270 ; iTemp10 [lr13:14]{int}[r2 r3] = @[iTemp7 [lr9:13]{_far * int}[DPTR]]
26310 ; *(iTemp6 [lr5:16]{_near * int}[r0]) := iTemp10 [lr13:14]{int}[r2 r3]
26336 ; iTemp6 [lr5:16]{_near * int}[r0] =
26341 ; iTemp6 [lr5:16]{_near * int}[r0] +
26358 ; goto _whilecontinue_0($1)
26370 ; _whilebreak_0($3) :
26380 ; iTemp2 [lr18:40]{short}[r2] := 0x0 {short}
26392 ; iTemp11 [lr19:40]{short}[r3] := 0x0 {short}
26404 ; iTemp21 [lr21:38]{short}[r4] := 0x0 {short}
26416 ; iTemp23 [lr22:38]{int}[r5 r6] := 0xa {int}
26435 ; iTemp17 [lr23:38]{int}[r7 r0] := 0x1e {int}
26464 ; iTemp13 [lr25:26]{char}[CC] = iTemp21 [lr21:38]{short}[r4] < 0xa {short}
26469 ; if iTemp13 [lr25:26]{char}[CC] == 0 goto _forbreak_0($7)
26514 ; iTemp2 [lr18:40]{short}[r2] = iTemp2 [lr18:40]{short}[r2] +
26519 ; iTemp21 [lr21:38]{short}[r4]
26545 ; iTemp15 [lr29:30]{short}[r1] = iTemp21 [lr21:38]{short}[r4] * 0x3 {short}
26578 ; iTemp11 [lr19:40]{short}[r3] = iTemp11 [lr19:40]{short}[r3] +
26583 ; iTemp15 [lr29:30]{short}[r1]
26602 ; iTemp17 [lr23:38]{int}[r7 r0]= iTemp17 [lr23:38]{int}[r7 r0]- 0x3 {short}
26649 ; _gint [lr0:0]{int} = _gint [lr0:0]{int} + iTemp17 [lr23:38]{int}[r7 r0]
26696 ; iTemp21 [lr21:38]{short}[r4] = iTemp21 [lr21:38]{short}[r4] + 0x1 {short}
26708 ; iTemp23 [lr22:38]{int}[r5 r6]= iTemp23 [lr22:38]{int}[r5 r6]- 0x1 {short}
26722 cjne r5,#0xff,00104$
26734 ; goto _forcond_0($4)
26746 ; _forbreak_0($7) :
26756 ; ret iTemp24 [lr40:41]{short}
26799 A few words about basic block successors, predecessors and dominators
26802 Successors are basic blocks
26803 \begin_inset LatexCommand \index{Basic blocks}
26807 that might execute after this basic block.
26809 Predecessors are basic blocks that might execute before reaching this basic
26812 Dominators are basic blocks that WILL execute before reaching this basic
26846 a) succList of [BB2] = [BB4], of [BB3] = [BB4], of [BB1] = [BB2,BB3]
26849 b) predList of [BB2] = [BB1], of [BB3] = [BB1], of [BB4] = [BB2,BB3]
26852 c) domVect of [BB4] = BB1 ...
26853 here we are not sure if BB2 or BB3 was executed but we are SURE that BB1
26861 \begin_inset LatexCommand \url{http://sdcc.sourceforge.net#Who}
26871 Thanks to all the other volunteer developers who have helped with coding,
26872 testing, web-page creation, distribution sets, etc.
26873 You know who you are :-)
26880 This document was initially written by Sandeep Dutta
26883 All product names mentioned herein may be trademarks
26884 \begin_inset LatexCommand \index{Trademarks}
26888 of their respective companies.
26895 To avoid confusion, the installation and building options for SDCC itself
26896 (chapter 2) are not part of the index.
26900 \begin_inset LatexCommand \printindex{}