1 #LyX 1.3 created this file. For more info see http://www.lyx.org/
6 pdftitle={SDCC Compiler User Guide},
7 pdfauthor={SDCC development team},
8 pdfsubject={installation, user manual},
9 pdfkeywords={8032, 8051, ansi, c, compiler, CPU, DS390,
10 embedded, GPL, HC08, manual, mcs51, PIC, Z80},
12 linkcolor=blue] {hyperref}
16 \emergencystretch=30pt
21 \inputencoding default
24 \paperfontsize default
26 \papersize letterpaper
31 \use_numerical_citations 0
32 \paperorientation portrait
39 \paragraph_separation indent
41 \quotes_language swedish
49 Please note: double dashed longoptions (e.g.
50 --version) are written this way: -
64 three consecutive dashes simply result in a long resp.
68 Architecture specific stuff (like memory models, code examples) should maybe
72 into seperate sections/chapters/appendices (it is hard to document PIC or
76 a 8051 centered document) - for now simply add.
79 SDCC Compiler User Guide
93 The above strings enclosed in $ are automatically updated by cvs
97 \begin_inset LatexCommand \tableofcontents{}
130 ompiler) is a Freeware, retargettable, optimizing ANSI-C compiler by
134 designed for 8 bit Microprocessors.
135 The current version targets Intel MCS51 based Microprocessors (8031, 8032,
137 \begin_inset LatexCommand \index{8031, 8032, 8051, 8052, mcs51 CPU}
141 , etc.), Dallas DS80C390 variants, Motorola HC08 and Zilog Z80 based MCUs.
142 It can be retargetted for other microprocessors, support for Microchip
143 PIC, Atmel AVR is under development.
144 The entire source code for the compiler is distributed under GPL.
145 SDCC uses ASXXXX & ASLINK, a Freeware, retargettable assembler & linker.
146 SDCC has extensive language extensions suitable for utilizing various microcont
147 rollers and underlying hardware effectively.
152 In addition to the MCU specific optimizations SDCC also does a host of standard
156 global sub expression elimination,
159 loop optimizations (loop invariant, strength reduction of induction variables
163 constant folding & propagation,
169 dead code elimination
179 For the back-end SDCC uses a global register allocation scheme which should
180 be well suited for other 8 bit MCUs.
185 The peep hole optimizer uses a rule based substitution mechanism which is
191 Supported data-types are:
194 char (8 bits, 1 byte),
197 short and int (16 bits, 2 bytes),
200 long (32 bit, 4 bytes)
207 The compiler also allows
209 inline assembler code
211 to be embedded anywhere in a function.
212 In addition, routines developed in assembly can also be called.
216 SDCC also provides an option (-
226 -cyclomatic) to report the relative complexity of a function.
227 These functions can then be further optimized, or hand coded in assembly
233 SDCC also comes with a companion source level debugger SDCDB, the debugger
234 currently uses ucSim a freeware simulator for 8051 and other micro-controllers.
239 The latest version can be downloaded from
240 \begin_inset LatexCommand \url{http://sdcc.sourceforge.net/snap.php}
250 Please note: the compiler will probably always be some steps ahead of this
255 \begin_inset LatexCommand \index{Status of documentation}
265 Obviously this has pros and cons
274 All packages used in this compiler system are
282 ; source code for all the sub-packages (pre-processor, assemblers, linkers
283 etc) is distributed with the package.
284 This documentation is maintained using a freeware word processor (LyX).
286 This program is free software; you can redistribute it and/or modify it
287 under the terms of the GNU General Public License
288 \begin_inset LatexCommand \index{GNU General Public License, GPL}
292 as published by the Free Software Foundation; either version 2, or (at
293 your option) any later version.
294 This program is distributed in the hope that it will be useful, but WITHOUT
295 ANY WARRANTY; without even the implied warranty
296 \begin_inset LatexCommand \index{warranty}
300 of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
301 See the GNU General Public License for more details.
302 You should have received a copy of the GNU General Public License along
303 with this program; if not, write to the Free Software Foundation, 59 Temple
304 Place - Suite 330, Boston, MA 02111-1307, USA.
305 In other words, you are welcome to use, share and improve this program.
306 You are forbidden to forbid anyone else to use, share and improve what
308 Help stamp out software-hoarding!
311 Typographic conventions
312 \begin_inset LatexCommand \index{Typographic conventions}
319 Throughout this manual, we will use the following convention.
320 Commands you have to type in are printed in
328 Code samples are printed in
333 Interesting items and new terms are printed in
338 Compatibility with previous versions
341 This version has numerous bug fixes compared with the previous version.
342 But we also introduced some incompatibilities with older versions.
343 Not just for the fun of it, but to make the compiler more stable, efficient
345 \begin_inset LatexCommand \index{ANSI-compliance}
350 \begin_inset LatexCommand \ref{sub:ANSI-Compliance}
354 for ANSI-Compliance).
360 short is now equivalent to int (16 bits), it used to be equivalent to char
361 (8 bits) which is not ANSI compliant
364 the default directory for gcc-builds where include, library and documentation
365 files are stored is now in /usr/local/share
368 char type parameters to vararg functions are casted to int unless explicitly
385 will push a as an int and as a char resp.
398 -regextend has been removed
411 -noregparms has been removed
424 -stack-after-data has been removed
429 <pending: more incompatibilities?>
435 What do you need before you start installation of SDCC? A computer, and
437 The preferred method of installation is to compile SDCC from source using
439 For Windows some pre-compiled binary distributions are available for your
441 You should have some experience with command line tools and compiler use.
447 The SDCC home page at
448 \begin_inset LatexCommand \url{http://sdcc.sourceforge.net/}
452 is a great place to find distribution sets.
453 You can also find links to the user mailing lists that offer help or discuss
454 SDCC with other SDCC users.
455 Web links to other SDCC related sites can also be found here.
456 This document can be found in the DOC directory of the source package as
458 Some of the other tools (simulator and assembler) included with SDCC contain
459 their own documentation and can be found in the source distribution.
460 If you want the latest unreleased software, the complete source package
461 is available directly by anonymous CVS on cvs.sdcc.sourceforge.net.
464 Wishes for the future
467 There are (and always will be) some things that could be done.
468 Here are some I can think of:
475 char KernelFunction3(char p) at 0x340;
483 \begin_inset LatexCommand \index{code banking (not supported)}
493 If you can think of some more, please see the section
494 \begin_inset LatexCommand \ref{sub:Requesting-Features}
498 about filing feature requests
499 \begin_inset LatexCommand \index{Requesting features}
504 \begin_inset LatexCommand \index{Feature request}
514 \begin_inset LatexCommand \index{Installation}
521 For most users it is sufficient to skip to either section
522 \begin_inset LatexCommand \ref{sub:Building-SDCC-on-Linux}
527 \begin_inset LatexCommand \ref{sub:Windows-Install}
532 More detailled instructions follow below.
536 \begin_inset LatexCommand \index{Options SDCC configuration}
543 The install paths, search paths and other options are defined when running
545 The defaults can be overridden by:
547 \labelwidthstring 00.00.0000
559 -prefix see table below
561 \labelwidthstring 00.00.0000
573 -exec_prefix see table below
575 \labelwidthstring 00.00.0000
587 -bindir see table below
589 \labelwidthstring 00.00.0000
601 -datadir see table below
603 \labelwidthstring 00.00.0000
605 docdir environment variable, see table below
607 \labelwidthstring 00.00.0000
609 include_dir_suffix environment variable, see table below
611 \labelwidthstring 00.00.0000
613 lib_dir_suffix environment variable, see table below
615 \labelwidthstring 00.00.0000
617 sdccconf_h_dir_separator environment variable, either / or
622 This character will only be used in sdccconf.h; don't forget it's a C-header,
623 therefore a double-backslash is needed there.
625 \labelwidthstring 00.00.0000
637 -disable-mcs51-port Excludes the Intel mcs51 port
639 \labelwidthstring 00.00.0000
651 -disable-gbz80-port Excludes the Gameboy gbz80 port
653 \labelwidthstring 00.00.0000
665 -disable-z80-port Excludes the z80 port
667 \labelwidthstring 00.00.0000
679 -disable-avr-port Excludes the AVR port
681 \labelwidthstring 00.00.0000
693 -disable-ds390-port Excludes the DS390 port
695 \labelwidthstring 00.00.0000
707 -disable-hc08-port Excludes the HC08 port
709 \labelwidthstring 00.00.0000
721 -disable-pic-port Excludes the PIC port
723 \labelwidthstring 00.00.0000
735 -disable-xa51-port Excludes the XA51 port
737 \labelwidthstring 00.00.0000
749 -disable-ucsim Disables configuring and building of ucsim
751 \labelwidthstring 00.00.0000
763 -disable-device-lib-build Disables automatically building device libraries
765 \labelwidthstring 00.00.0000
777 -disable-packihx Disables building packihx
779 \labelwidthstring 00.00.0000
791 -enable-libgc Use the Bohem memory allocator.
792 Lower runtime footprint.
795 Furthermore the environment variables CC, CFLAGS, ...
796 the tools and their arguments can be influenced.
797 Please see `configure -
807 -help` and the man/info pages of `configure` for details.
811 The names of the standard libraries STD_LIB, STD_INT_LIB, STD_LONG_LIB,
812 STD_FP_LIB, STD_DS390_LIB, STD_XA51_LIB and the environment variables SDCC_DIR_
813 NAME, SDCC_INCLUDE_NAME, SDCC_LIB_NAME are defined by `configure` too.
814 At the moment it's not possible to change the default settings (it was
815 simply never required).
819 These configure options are compiled into the binaries, and can only be
820 changed by rerunning 'configure' and recompiling SDCC.
821 The configure options are written in
825 to distinguish them from run time environment variables (see section search
831 \begin_inset Quotes sld
835 \begin_inset Quotes srd
838 are used by the SDCC team to build the official Win32 binaries.
839 The SDCC team uses Mingw32 to build the official Windows binaries, because
846 a gcc compiler and last but not least
849 the binaries can be built by cross compiling on Sourceforge's compile farm.
852 See the examples, how to pass the Win32 settings to 'configure'.
853 The other Win32 builds using Borland, VC or whatever don't use 'configure',
854 but a header file sdcc_vc_in.h is the same as sdccconf.h built by 'configure'
866 <lyxtabular version="3" rows="8" columns="3">
868 <column alignment="block" valignment="top" leftline="true" width="0in">
869 <column alignment="block" valignment="top" leftline="true" width="0in">
870 <column alignment="block" valignment="top" leftline="true" rightline="true" width="0in">
871 <row topline="true" bottomline="true">
872 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
880 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
888 <cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
898 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
908 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
916 <cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
928 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
938 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
948 <cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
960 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
970 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
982 <cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
998 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
1008 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
1020 <cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
1031 <row topline="true">
1032 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
1042 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
1054 <cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
1069 <row topline="true">
1070 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
1080 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
1088 <cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
1097 <row topline="true" bottomline="true">
1098 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
1108 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
1116 <cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
1134 'configure' also computes relative paths.
1135 This is needed for full relocatability of a binary package and to complete
1136 search paths (see section search paths below):
1142 \begin_inset Tabular
1143 <lyxtabular version="3" rows="4" columns="3">
1145 <column alignment="block" valignment="top" leftline="true" width="0in">
1146 <column alignment="block" valignment="top" leftline="true" width="0in">
1147 <column alignment="block" valignment="top" leftline="true" rightline="true" width="0in">
1148 <row topline="true" bottomline="true">
1149 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
1157 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
1165 <cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
1174 <row topline="true" bottomline="true">
1175 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
1185 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
1193 <cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
1202 <row bottomline="true">
1203 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
1213 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
1221 <cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
1230 <row bottomline="true">
1231 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
1241 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
1249 <cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
1282 \begin_inset Quotes srd
1286 \begin_inset Quotes srd
1300 \begin_inset Quotes srd
1304 \begin_inset Quotes srd
1332 To cross compile on linux for Mingw32 (see also 'sdcc/support/scripts/sdcc_mingw
1341 \begin_inset Quotes srd
1344 i586-mingw32msvc-gcc
1345 \begin_inset Quotes srd
1349 \begin_inset Quotes srd
1352 i586-mingw32msvc-g++
1353 \begin_inset Quotes srd
1361 \begin_inset Quotes srd
1364 i586-mingw32msvc-ranlib
1365 \begin_inset Quotes srd
1373 \begin_inset Quotes srd
1376 i586-mingw32msvc-strip
1377 \begin_inset Quotes srd
1395 \begin_inset Quotes srd
1399 \begin_inset Quotes srd
1417 \begin_inset Quotes srd
1421 \begin_inset Quotes srd
1429 \begin_inset Quotes srd
1433 \begin_inset Quotes srd
1441 \begin_inset Quotes srd
1445 \begin_inset Quotes srd
1453 \begin_inset Quotes srd
1457 \begin_inset Quotes srd
1464 sdccconf_h_dir_separator=
1465 \begin_inset Quotes srd
1477 \begin_inset Quotes srd
1494 -disable-device-lib-build
1522 -host=i586-mingw32msvc -
1532 -build=unknown-unknown-linux-gnu
1536 \begin_inset Quotes sld
1540 \begin_inset Quotes srd
1543 compile on Cygwin for Mingw32 (see also sdcc/support/scripts/sdcc_cygwin_mingw32
1552 \begin_inset Quotes srd
1556 \begin_inset Quotes srd
1564 \begin_inset Quotes srd
1568 \begin_inset Quotes srd
1586 \begin_inset Quotes srd
1590 \begin_inset Quotes srd
1608 \begin_inset Quotes srd
1612 \begin_inset Quotes srd
1620 \begin_inset Quotes srd
1624 \begin_inset Quotes srd
1632 \begin_inset Quotes srd
1636 \begin_inset Quotes srd
1644 \begin_inset Quotes srd
1648 \begin_inset Quotes srd
1655 sdccconf_h_dir_separator=
1656 \begin_inset Quotes srd
1668 \begin_inset Quotes srd
1688 'configure' is quite slow on Cygwin (at least on windows before Win2000/XP).
1699 -C' turns on caching, which gives a little bit extra speed.
1700 However if options are changed, it can be necessary to delete the config.cache
1705 \begin_inset LatexCommand \label{sub:Install-paths}
1710 \begin_inset LatexCommand \index{Install paths}
1716 \added_space_top medskip \align center
1718 \begin_inset Tabular
1719 <lyxtabular version="3" rows="5" columns="4">
1721 <column alignment="center" valignment="top" leftline="true" width="0">
1722 <column alignment="center" valignment="top" leftline="true" width="0">
1723 <column alignment="center" valignment="top" leftline="true" width="0">
1724 <column alignment="center" valignment="top" leftline="true" rightline="true" width="0">
1725 <row topline="true" bottomline="true">
1726 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
1736 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
1746 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
1756 <cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
1767 <row topline="true">
1768 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
1776 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
1786 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
1794 <cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
1807 <row topline="true">
1808 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
1816 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
1823 $DATADIR/ $INCLUDE_DIR_SUFFIX
1826 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
1831 /usr/local/share/sdcc/include
1834 <cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
1847 <row topline="true">
1848 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
1856 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
1863 $DATADIR/$LIB_DIR_SUFFIX
1866 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
1871 /usr/local/share/sdcc/lib
1874 <cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
1887 <row topline="true" bottomline="true">
1888 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
1896 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
1906 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
1911 /usr/local/share/sdcc/doc
1914 <cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
1936 *compiler, preprocessor, assembler, and linker
1942 is auto-appended by the compiler, e.g.
1943 small, large, z80, ds390 etc
1946 The install paths can still be changed during `make install` with e.g.:
1949 make install prefix=$(HOME)/local/sdcc
1952 Of course this doesn't change the search paths compiled into the binaries.
1956 \begin_inset LatexCommand \label{sub:Search-Paths}
1961 \begin_inset LatexCommand \index{Search path}
1968 Some search paths or parts of them are determined by configure variables
1973 , see section above).
1974 Further search paths are determined by environment variables during runtime.
1977 The paths searched when running the compiler are as follows (the first catch
1983 Binary files (preprocessor, assembler and linker)
1989 \begin_inset Tabular
1990 <lyxtabular version="3" rows="4" columns="3">
1992 <column alignment="block" valignment="top" leftline="true" width="0in">
1993 <column alignment="block" valignment="top" leftline="true" width="0in">
1994 <column alignment="block" valignment="top" leftline="true" rightline="true" width="0in">
1995 <row topline="true" bottomline="true">
1996 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
2004 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
2012 <cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
2021 <row topline="true">
2022 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
2032 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
2040 <cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
2051 <row topline="true">
2052 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
2057 Path of argv[0] (if available)
2060 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
2068 <cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
2077 <row topline="true" bottomline="true">
2078 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
2086 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
2094 <cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
2119 \begin_inset Tabular
2120 <lyxtabular version="3" rows="6" columns="3">
2122 <column alignment="block" valignment="top" leftline="true" width="1.5in">
2123 <column alignment="block" valignment="top" leftline="true" width="1.5in">
2124 <column alignment="block" valignment="top" leftline="true" rightline="true" width="0in">
2125 <row topline="true" bottomline="true">
2126 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
2134 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
2142 <cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
2151 <row topline="true">
2152 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
2170 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
2188 <cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
2207 <row topline="true">
2208 <cell alignment="left" valignment="top" topline="true" leftline="true" usebox="none">
2216 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
2224 <cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
2233 <row topline="true">
2234 <cell alignment="left" valignment="top" topline="true" leftline="true" usebox="none">
2248 <cell alignment="left" valignment="top" topline="true" leftline="true" usebox="none">
2260 <cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
2271 <row topline="true">
2272 <cell alignment="left" valignment="top" topline="true" leftline="true" usebox="none">
2290 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
2340 <cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
2353 <row topline="true" bottomline="true">
2354 <cell alignment="left" valignment="top" topline="true" leftline="true" usebox="none">
2370 <cell alignment="left" valignment="top" topline="true" leftline="true" usebox="none">
2375 /usr/local/share/sdcc/
2380 <cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
2408 -nostdinc disables the last two search paths.
2418 With the exception of
2419 \begin_inset Quotes sld
2433 \begin_inset Quotes srd
2440 is auto-appended by the compiler (e.g.
2441 small, large, z80, ds390 etc.).
2448 \begin_inset Tabular
2449 <lyxtabular version="3" rows="6" columns="3">
2451 <column alignment="block" valignment="top" leftline="true" width="1.7in">
2452 <column alignment="block" valignment="top" leftline="true" width="1.2in">
2453 <column alignment="block" valignment="top" leftline="true" rightline="true" width="1.2in">
2454 <row topline="true" bottomline="true">
2455 <cell alignment="left" valignment="top" topline="true" leftline="true" usebox="none">
2463 <cell alignment="left" valignment="top" topline="true" leftline="true" usebox="none">
2471 <cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
2480 <row topline="true">
2481 <cell alignment="left" valignment="top" topline="true" leftline="true" usebox="none">
2499 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
2517 <cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
2536 <row topline="true">
2537 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
2549 <cell alignment="left" valignment="top" topline="true" leftline="true" usebox="none">
2561 <cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
2576 <row topline="true">
2577 <cell alignment="left" valignment="top" topline="true" leftline="true" usebox="none">
2588 $LIB_DIR_SUFFIX/<model>
2591 <cell alignment="left" valignment="top" topline="true" leftline="true" usebox="none">
2605 <cell alignment="left" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
2622 <row topline="true">
2623 <cell alignment="left" valignment="top" topline="true" leftline="true" usebox="none">
2638 $LIB_DIR_SUFFIX/<model>
2641 <cell alignment="left" valignment="top" topline="true" leftline="true" usebox="none">
2694 <cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
2750 <row topline="true" bottomline="true">
2751 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
2760 $LIB_DIR_SUFFIX/<model>
2763 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
2768 /usr/local/share/sdcc/
2775 <cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
2793 Don't delete any of the stray spaces in the table above without checking
2794 the HTML output (last line)!
2810 -nostdlib disables the last two search paths.
2814 \begin_inset LatexCommand \index{Building SDCC}
2821 Building SDCC on Linux
2822 \begin_inset LatexCommand \label{sub:Building-SDCC-on-Linux}
2831 Download the source package
2833 either from the SDCC CVS repository or from the nightly snapshots
2835 , it will be named something like sdcc
2846 \begin_inset LatexCommand \url{http://sdcc.sourceforge.net/snap.php}
2855 Bring up a command line terminal, such as xterm.
2860 Unpack the file using a command like:
2863 "tar -xvzf sdcc.src.tar.gz
2868 , this will create a sub-directory called sdcc with all of the sources.
2871 Change directory into the main SDCC directory, for example type:
2888 This configures the package for compilation on your system.
2904 All of the source packages will compile, this can take a while.
2920 This copies the binary executables, the include files, the libraries and
2921 the documentation to the install directories.
2922 Proceed with section
2923 \begin_inset LatexCommand \ref{sec:Testing-the-SDCC}
2930 Building SDCC on OSX 2.x
2933 Follow the instruction for Linux.
2937 On OSX 2.x it was reported, that the default gcc (version 3.1 20020420 (prerelease
2938 )) fails to compile SDCC.
2939 Fortunately there's also gcc 2.9.x installed, which works fine.
2940 This compiler can be selected by running 'configure' with:
2943 ./configure CC=gcc2 CXX=g++2
2946 Cross compiling SDCC on Linux for Windows
2949 With the Mingw32 gcc cross compiler it's easy to compile SDCC for Win32.
2950 See section 'Configure Options'.
2953 Building SDCC on Windows
2956 With the exception of Cygwin the SDCC binaries uCsim and sdcdb can't be
2958 They use Unix-sockets, which are not available on Win32.
2961 Building SDCC using Cygwin and Mingw32
2964 For building and installing a Cygwin executable follow the instructions
2970 \begin_inset Quotes sld
2974 \begin_inset Quotes srd
2977 Win32-binary can be built, which will not need the Cygwin-DLL.
2978 For the necessary 'configure' options see section 'configure options' or
2979 the script 'sdcc/support/scripts/sdcc_cygwin_mingw32'.
2983 In order to install Cygwin on Windows download setup.exe from
2984 \begin_inset LatexCommand \url[www.cygwin.com]{http://www.cygwin.com/}
2990 \begin_inset Quotes sld
2993 default text file type
2994 \begin_inset Quotes srd
2998 \begin_inset Quotes sld
3002 \begin_inset Quotes srd
3005 and download/install at least the following packages.
3006 Some packages are selected by default, others will be automatically selected
3007 because of dependencies with the manually selected packages.
3008 Never deselect these packages!
3017 gcc ; version 3.x is fine, no need to use the old 2.9x
3020 binutils ; selected with gcc
3026 rxvt ; a nice console, which makes life much easier under windoze (see below)
3029 man ; not really needed for building SDCC, but you'll miss it sooner or
3033 less ; not really needed for building SDCC, but you'll miss it sooner or
3037 cvs ; only if you use CVS access
3040 If you want to develop something you'll need:
3043 python ; for the regression tests
3046 gdb ; the gnu debugger, together with the nice GUI
3047 \begin_inset Quotes sld
3051 \begin_inset Quotes srd
3057 openssh ; to access the CF or commit changes
3060 autoconf and autoconf-devel ; if you want to fight with 'configure', don't
3061 use autoconf-stable!
3064 rxvt is a nice console with history.
3065 Replace in your cygwin.bat the line
3084 rxvt -sl 1000 -fn "Lucida Console-12" -sr -cr red
3087 -bg black -fg white -geometry 100x65 -e bash -
3100 Text selected with the mouse is automatically copied to the clipboard, pasting
3101 works with shift-insert.
3105 The other good tip is to make sure you have no //c/-style paths anywhere,
3106 use /cygdrive/c/ instead.
3107 Using // invokes a network lookup which is very slow.
3109 \begin_inset Quotes sld
3113 \begin_inset Quotes srd
3116 is too long, you can change it with e.g.
3122 SDCC sources use the unix line ending LF.
3123 Life is much easier, if you store the source tree on a drive which is mounted
3125 And use an editor which can handle LF-only line endings.
3126 Make sure not to commit files with windows line endings.
3127 The tabulator spacing
3128 \begin_inset LatexCommand \index{tabulator spacing (8)}
3132 used in the project is 8.
3135 Building SDCC Using Microsoft Visual C++ 6.0/NET (MSVC)
3140 Download the source package
3142 either from the SDCC CVS repository or from the
3143 \begin_inset LatexCommand \url[nightly snapshots]{http://sdcc.sourceforge.net/snap.php}
3149 , it will be named something like sdcc
3156 SDCC is distributed with all the projects, workspaces, and files you need
3157 to build it using Visual C++ 6.0/NET (except for sdcdb.exe which currently
3158 doesn't build under MSVC).
3159 The workspace name is 'sdcc.dsw'.
3160 Please note that as it is now, all the executables are created in a folder
3164 Once built you need to copy the executables from sdcc
3168 bin before running SDCC.
3173 In order to build SDCC with MSVC you need win32 executables of bison.exe,
3174 flex.exe, and gawk.exe.
3175 One good place to get them is
3176 \begin_inset LatexCommand \url[here]{http://unxutils.sourceforge.net}
3184 Download the file UnxUtils
3185 \begin_inset LatexCommand \index{UnxUtils}
3190 Now you have to install the utilities and setup MSVC so it can locate the
3192 Here there are two alternatives (choose one!):
3199 a) Extract UnxUtils.zip to your C:
3201 hard disk PRESERVING the original paths, otherwise bison won't work.
3202 (If you are using WinZip make certain that 'Use folder names' is selected)
3206 b) In the Visual C++ IDE click Tools, Options, select the Directory tab,
3207 in 'Show directories for:' select 'Executable files', and in the directories
3208 window add a new path: 'C:
3218 (As a side effect, you get a bunch of Unix utilities that could be useful,
3219 such as diff and patch.)
3226 This one avoids extracting a bunch of files you may not use, but requires
3231 a) Create a directory were to put the tools needed, or use a directory already
3239 b) Extract 'bison.exe', 'bison.hairy', 'bison.simple', 'flex.exe', and gawk.exe
3240 to such directory WITHOUT preserving the original paths.
3241 (If you are using WinZip make certain that 'Use folder names' is not selected)
3245 c) Rename bison.exe to '_bison.exe'.
3249 d) Create a batch file 'bison.bat' in 'C:
3253 ' and add these lines:
3273 _bison %1 %2 %3 %4 %5 %6 %7 %8 %9
3277 Steps 'c' and 'd' are needed because bison requires by default that the
3278 files 'bison.simple' and 'bison.hairy' reside in some weird Unix directory,
3279 '/usr/local/share/' I think.
3280 So it is necessary to tell bison where those files are located if they
3281 are not in such directory.
3282 That is the function of the environment variables BISON_SIMPLE and BISON_HAIRY.
3286 e) In the Visual C++ IDE click Tools, Options, select the Directory tab,
3287 in 'Show directories for:' select 'Executable files', and in the directories
3288 window add a new path: 'c:
3291 Note that you can use any other path instead of 'c:
3293 util', even the path where the Visual C++ tools are, probably: 'C:
3297 Microsoft Visual Studio
3302 So you don't have to execute step 'e' :)
3306 Open 'sdcc.dsw' in Visual Studio, click 'build all', when it finishes copy
3307 the executables from sdcc
3311 bin, and you can compile using SDCC.
3314 Building SDCC Using Borland
3317 From the sdcc directory, run the command "make -f Makefile.bcc".
3318 This should regenerate all the .exe files in the bin directory except for
3319 sdcdb.exe (which currently doesn't build under Borland C++).
3322 If you modify any source files and need to rebuild, be aware that the dependenci
3323 es may not be correctly calculated.
3324 The safest option is to delete all .obj files and run the build again.
3325 From a Cygwin BASH prompt, this can easily be done with the command (be
3326 sure you are in the sdcc directory):
3336 ( -name '*.obj' -o -name '*.lib' -o -name '*.rul'
3338 ) -print -exec rm {}
3347 or on Windows NT/2000/XP from the command prompt with the command:
3354 del /s *.obj *.lib *.rul
3357 from the sdcc directory.
3360 Windows Install Using a Binary Package
3361 \begin_inset LatexCommand \label{sub:Windows-Install}
3368 Download the binary package from
3369 \begin_inset LatexCommand \url{http://sdcc.sourceforge.net/snap.php}
3373 and unpack it using your favorite unpacking tool (gunzip, WinZip, etc).
3374 This should unpack to a group of sub-directories.
3375 An example directory structure after unpacking the mingw32 package is:
3380 bin for the executables, c:
3388 lib for the include and libraries.
3391 Adjust your environment variable PATH to include the location of the bin
3392 directory or start sdcc using the full path.
3395 Building the Documentation
3398 If the necessary tools (LyX, LaTeX, LaTeX2HTML) are installed it is as easy
3399 as changing into the doc directory and typing
3403 \begin_inset Quotes srd
3407 \begin_inset Quotes srd
3414 You're invited to make changes and additions to this manual (sdcc/doc/sdccman.ly
3417 \begin_inset LatexCommand \url{www.lyx.org}
3421 as editor this is straightforward.
3422 If you want to avoid installing the tools you will have some success with
3423 a bootable Knoppix CD
3424 \begin_inset LatexCommand \url{http://www.knoppix.net}
3429 Prebuilt documentation in html and pdf format is available from
3430 \begin_inset LatexCommand \url{http://sdcc.sourceforge.net/snap.php}
3437 Reading the Documentation
3440 Currently reading the document in pdf format is recommended, as for unknown
3441 reason the hyperlinks are working there whereas in the html version they
3448 If you should know why please drop us a note
3452 You'll find the pdf version at
3453 \begin_inset LatexCommand \url{http://sdcc.sourceforge.net/doc/sdccman.pdf}
3459 This documentation is in some aspects different from a commercial documentation:
3463 It tries to document SDCC for several processor architectures in one document
3464 (commercially these probably would be separate documents/products).
3466 \begin_inset LatexCommand \index{Status of documentation}
3470 currently matches SDCC for mcs51 and DS390 best and does give too few informati
3472 Z80, PIC14, PIC16 and HC08.
3475 There are many references pointing away from this documentation.
3476 Don't let this distract you.
3478 was a reference like
3479 \begin_inset LatexCommand \url{www.opencores.org}
3483 together with a statement
3484 \begin_inset Quotes sld
3487 some processors which are targetted by SDCC can be implemented in a
3504 \begin_inset LatexCommand \index{fpga (field programmable gate array)}
3509 \begin_inset Quotes srd
3512 we expect you to have a quick look there and come back.
3513 If you read this you are on the right track.
3516 Some sections attribute more space to problems, restrictions and warnings
3517 than to the solution.
3520 The installation section and the section about the debugger is intimidating.
3523 There are still lots of typos and there are more different writing styles
3527 Testing the SDCC Compiler
3528 \begin_inset LatexCommand \label{sec:Testing-the-SDCC}
3535 The first thing you should do after installing your SDCC compiler is to
3551 \begin_inset LatexCommand \index{version}
3558 at the prompt, and the program should run and tell you the version.
3559 If it doesn't run, or gives a message about not finding sdcc program, then
3560 you need to check over your installation.
3561 Make sure that the sdcc bin directory is in your executable search path
3562 defined by the PATH environment setting (
3567 \begin_inset LatexCommand \ref{sub:Install-Trouble-shooting}
3574 Install trouble-shooting for suggestions
3577 Make sure that the sdcc program is in the bin folder, if not perhaps something
3578 did not install correctly.
3586 is commonly installed as described in section
3587 \begin_inset Quotes sld
3590 Install and search paths
3591 \begin_inset Quotes srd
3600 Make sure the compiler works on a very simple example.
3601 Type in the following test.c program using your favorite
3627 Compile this using the following command:
3636 If all goes well, the compiler will generate a test.asm and test.rel file.
3637 Congratulations, you've just compiled your first program with SDCC.
3638 We used the -c option to tell SDCC not to link the generated code, just
3639 to keep things simple for this step.
3647 The next step is to try it with the linker.
3657 If all goes well the compiler will link with the libraries and produce
3658 a test.ihx output file.
3663 (no test.ihx, and the linker generates warnings), then the problem is most
3672 usr/local/share/sdcc/lib directory
3679 \begin_inset LatexCommand \ref{sub:Install-Trouble-shooting}
3686 Install trouble-shooting for suggestions).
3694 The final test is to ensure
3702 header files and libraries.
3703 Edit test.c and change it to the following:
3720 strcpy(str1, "testing");
3727 Compile this by typing
3734 This should generate a test.ihx output file, and it should give no warnings
3735 such as not finding the string.h file.
3736 If it cannot find the string.h file, then the problem is that
3740 cannot find the /usr/local/share/sdcc/include directory
3747 \begin_inset LatexCommand \ref{sub:Install-Trouble-shooting}
3754 Install trouble-shooting section for suggestions).
3772 \begin_inset LatexCommand \index{-\/-print-search-dirs}
3776 to find exactly where SDCC is looking for the include and lib files.
3779 Install Trouble-shooting
3780 \begin_inset LatexCommand \label{sub:Install-Trouble-shooting}
3785 \begin_inset LatexCommand \index{Install trouble-shooting}
3792 If SDCC does not build correctly
3795 A thing to try is starting from scratch by unpacking the .tgz source package
3796 again in an empty directory.
3804 ./configure 2>&1 | tee configure.log
3818 make 2>&1 | tee make.log
3825 If anything goes wrong, you can review the log files to locate the problem.
3826 Or a relevant part of this can be attached to an email that could be helpful
3827 when requesting help from the mailing list.
3831 \begin_inset Quotes sld
3835 \begin_inset Quotes srd
3842 \begin_inset Quotes sld
3846 \begin_inset Quotes srd
3849 command is a script that analyzes your system and performs some configuration
3850 to ensure the source package compiles on your system.
3851 It will take a few minutes to run, and will compile a few tests to determine
3852 what compiler features are installed.
3856 \begin_inset Quotes sld
3860 \begin_inset Quotes srd
3866 This runs the GNU make tool, which automatically compiles all the source
3867 packages into the final installed binary executables.
3871 \begin_inset Quotes sld
3875 \begin_inset Quotes erd
3881 This will install the compiler, other executables libraries and include
3882 files into the appropriate directories.
3884 \begin_inset LatexCommand \ref{sub:Install-paths}
3890 \begin_inset LatexCommand \ref{sub:Search-Paths}
3895 about install and search paths.
3897 On most systems you will need super-user privileges to do this.
3903 SDCC is not just a compiler, but a collection of tools by various developers.
3904 These include linkers, assemblers, simulators and other components.
3905 Here is a summary of some of the components.
3906 Note that the included simulator and assembler have separate documentation
3907 which you can find in the source package in their respective directories.
3908 As SDCC grows to include support for other processors, other packages from
3909 various developers are included and may have their own sets of documentation.
3913 You might want to look at the files which are installed in <installdir>.
3914 At the time of this writing, we find the following programs for gcc-builds:
3918 In <installdir>/bin:
3921 sdcc - The compiler.
3924 sdcpp - The C preprocessor.
3927 asx8051 - The assembler for 8051 type processors.
3934 as-gbz80 - The Z80 and GameBoy Z80 assemblers.
3937 aslink -The linker for 8051 type processors.
3944 link-gbz80 - The Z80 and GameBoy Z80 linkers.
3947 s51 - The ucSim 8051 simulator.
3950 sdcdb - The source debugger.
3953 packihx - A tool to pack (compress) Intel hex files.
3956 In <installdir>/share/sdcc/include
3962 In <installdir>/share/sdcc/lib
3965 the subdirs src and small, large, z80, gbz80 and ds390 with the precompiled
3969 In <installdir>/share/sdcc/doc
3975 As development for other processors proceeds, this list will expand to include
3976 executables to support processors like AVR, PIC, etc.
3982 This is the actual compiler, it in turn uses the c-preprocessor and invokes
3983 the assembler and linkage editor.
3986 sdcpp - The C-Preprocessor
3990 \begin_inset LatexCommand \index{sdcpp (preprocessor)}
3994 is a modified version of the GNU preprocessor.
3995 The C preprocessor is used to pull in #include sources, process #ifdef
3996 statements, #defines and so on.
4007 - The Assemblers and Linkage Editors
4010 This is retargettable assembler & linkage editor, it was developed by Alan
4012 John Hartman created the version for 8051, and I (Sandeep) have made some
4013 enhancements and bug fixes for it to work properly with SDCC.
4020 \begin_inset LatexCommand \index{s51}
4024 is a freeware, opensource simulator developed by Daniel Drotos (
4025 \begin_inset LatexCommand \url{mailto:drdani@mazsola.iit.uni-miskolc.hu}
4030 The simulator is built as part of the build process.
4031 For more information visit Daniel's web site at:
4032 \begin_inset LatexCommand \url{http://mazsola.iit.uni-miskolc.hu/~drdani/embedded/s51}
4037 It currently supports the core mcs51, the Dallas DS80C390 and the Phillips
4041 sdcdb - Source Level Debugger
4045 \begin_inset LatexCommand \index{sdcdb (debugger)}
4049 is the companion source level debugger.
4050 More about sdcdb in section
4051 \begin_inset LatexCommand \ref{cha:Debugging-with-SDCDB}
4056 The current version of the debugger uses Daniel's Simulator S51
4057 \begin_inset LatexCommand \index{s51}
4061 , but can be easily changed to use other simulators.
4071 Single Source File Projects
4074 For single source file 8051 projects the process is very simple.
4075 Compile your programs with the following command
4078 "sdcc sourcefile.c".
4082 This will compile, assemble and link your source file.
4083 Output files are as follows:
4087 \begin_inset LatexCommand \index{<file>.asm}
4092 \begin_inset LatexCommand \index{Assembler source}
4096 file created by the compiler
4100 \begin_inset LatexCommand \index{<file>.lst}
4105 \begin_inset LatexCommand \index{Assembler listing}
4109 file created by the Assembler
4113 \begin_inset LatexCommand \index{<file>.rst}
4118 \begin_inset LatexCommand \index{Assembler listing}
4122 file updated with linkedit information, created by linkage editor
4126 \begin_inset LatexCommand \index{<file>.sym}
4131 \begin_inset LatexCommand \index{Symbol listing}
4135 for the sourcefile, created by the assembler
4139 \begin_inset LatexCommand \index{<file>.rel}
4144 \begin_inset LatexCommand \index{<file>.o}
4149 \begin_inset LatexCommand \index{Object file}
4153 created by the assembler, input to Linkage editor
4157 \begin_inset LatexCommand \index{<file>.map}
4162 \begin_inset LatexCommand \index{Memory map}
4166 for the load module, created by the Linker
4170 \begin_inset LatexCommand \index{<file>.mem}
4174 - A file with a summary of the memory usage
4178 \begin_inset LatexCommand \index{<file>.ihx}
4182 - The load module in Intel hex format
4183 \begin_inset LatexCommand \index{Intel hex format}
4187 (you can select the Motorola S19 format
4188 \begin_inset LatexCommand \index{Motorola S19 format}
4203 \begin_inset LatexCommand \index{-\/-out-fmt-s19}
4208 If you need another format you might want to use
4215 \begin_inset LatexCommand \index{objdump (tool)}
4226 \begin_inset LatexCommand \index{srecord (tool)}
4231 Both formats are documented in the documentation of srecord
4232 \begin_inset LatexCommand \index{srecord (tool)}
4240 \begin_inset LatexCommand \index{<file>.adb}
4244 - An intermediate file containing debug information needed to create the
4256 \begin_inset LatexCommand \index{-\/-debug}
4264 \begin_inset LatexCommand \index{<file>.cdb}
4268 - An optional file (with -
4278 -debug) containing debug information.
4279 The format is documented in cdbfileformat.pdf.
4284 \begin_inset LatexCommand \index{<file> (no extension)}
4288 An optional AOMF or AOMF51
4289 \begin_inset LatexCommand \index{AOMF, AOMF51}
4293 file containing debug information (generated with option -
4320 ormat is commonly used by third party tools (debuggers
4321 \begin_inset LatexCommand \index{Debugger}
4325 , simulators, emulators)
4329 \begin_inset LatexCommand \index{<file>.dump*}
4333 - Dump file to debug the compiler it self (generated with option -
4343 -dumpall) (see section
4344 \begin_inset LatexCommand \ref{sub:Intermediate-Dump-Options}
4350 \begin_inset LatexCommand \ref{sub:The-anatomy-of}
4356 \begin_inset Quotes sld
4359 Anatomy of the compiler
4360 \begin_inset Quotes srd
4366 Projects with Multiple Source Files
4369 SDCC can compile only ONE file at a time.
4370 Let us for example assume that you have a project containing the following
4375 foo1.c (contains some functions)
4377 foo2.c (contains some more functions)
4379 foomain.c (contains more functions and the function main)
4387 The first two files will need to be compiled separately with the commands:
4419 Then compile the source file containing the
4424 \begin_inset LatexCommand \index{Linker}
4428 the files together with the following command:
4436 foomain.c\SpecialChar ~
4437 foo1.rel\SpecialChar ~
4442 \begin_inset LatexCommand \index{<file>.rel}
4454 can be separately compiled as well:
4465 sdcc foomain.rel foo1.rel foo2.rel
4472 The file containing the
4487 file specified in the command line, since the linkage editor processes
4488 file in the order they are presented to it.
4489 The linker is invoked from SDCC using a script file with extension .lnk
4490 \begin_inset LatexCommand \index{<file>.lnk}
4495 You can view this file to troubleshoot linking problems such as those arising
4496 from missing libraries.
4499 Projects with Additional Libraries
4500 \begin_inset LatexCommand \index{Libraries}
4507 Some reusable routines may be compiled into a library, see the documentation
4508 for the assembler and linkage editor (which are in <installdir>/share/sdcc/doc)
4512 \begin_inset LatexCommand \index{<file>.lib}
4519 Libraries created in this manner can be included in the command line.
4520 Make sure you include the -L <library-path> option to tell the linker where
4521 to look for these files if they are not in the current directory.
4522 Here is an example, assuming you have the source file
4534 (if that is not the same as your current project):
4541 sdcc foomain.c foolib.lib -L mylib
4552 must be an absolute path name.
4556 The most efficient way to use libraries is to keep separate modules in separate
4558 The lib file now should name all the modules.rel
4559 \begin_inset LatexCommand \index{<file>.rel}
4564 For an example see the standard library file
4568 in the directory <installdir>/share/lib/small.
4571 Using sdcclib to Create and Manage Libraries
4572 \begin_inset LatexCommand \index{sdcclib}
4579 Alternatively, instead of having a .rel file for each entry on the library
4580 file as described in the preceding section, sdcclib can be used to embed
4581 all the modules belonging to such library in the library file itself.
4582 This results in a larger library file, but it greatly reduces the number
4583 of disk files accessed by the linker.
4584 Additionally, the packed library file contains an index of all include
4585 modules and symbols that significantly speeds up the linking process.
4586 To display a list of options supported by sdcclib type:
4595 \begin_inset LatexCommand \index{sdcclib}
4606 To create a new library file, start by compiling all the required modules.
4639 This will create files _divsint.rel, _divuint.rel, _modsint.rel, _moduint.rel,
4641 The next step is to add the .rel files to the library file:
4648 sdcclib libint.lib _divsint.rel
4649 \begin_inset LatexCommand \index{sdcclib}
4658 sdcclib libint.lib _divuint.rel
4663 sdcclib libint.lib _modsint.rel
4668 sdcclib libint.lib _moduint.rel
4673 sdcclib libint.lib _mulint.rel
4680 If the file already exists in the library, it will be replaced.
4681 To see what modules and symbols are included in the library, options -s
4682 and -m are available.
4689 sdcclib -s libint.lib
4690 \begin_inset LatexCommand \index{sdcclib}
4794 If the source files are compiled using --debug, the corresponding debug
4795 information file .adb will be include in the library file as well.
4796 The library files created with sdcclib are plain text files, so they can
4797 be viewed with a text editor.
4798 It is not recomended to modify a library file created with sdcclib using
4799 a text editor, as there are file indexes numbers located accross the file
4800 used by the linker to quickly locate the required module to link.
4801 Once a .rel file (as well as a .adb file) is added to a library using sdcclib,
4802 it can be safely deleted, since all the information required for linking
4803 is embedded in the library file itself.
4804 Library files created using sdcclib are used as described in the preceding
4808 Command Line Options
4809 \begin_inset LatexCommand \index{Command Line Options}
4816 Processor Selection Options
4817 \begin_inset LatexCommand \index{Options processor selection}
4822 \begin_inset LatexCommand \index{Processor selection options}
4828 \labelwidthstring 00.00.0000
4833 \begin_inset LatexCommand \index{-mmcs51}
4839 Generate code for the Intel MCS51
4840 \begin_inset LatexCommand \index{MCS51}
4844 family of processors.
4845 This is the default processor target.
4847 \labelwidthstring 00.00.0000
4852 \begin_inset LatexCommand \index{-mds390}
4858 Generate code for the Dallas DS80C390
4859 \begin_inset LatexCommand \index{DS80C390}
4865 \labelwidthstring 00.00.0000
4870 \begin_inset LatexCommand \index{-mds400}
4876 Generate code for the Dallas DS80C400
4877 \begin_inset LatexCommand \index{DS80C400}
4883 \labelwidthstring 00.00.0000
4888 \begin_inset LatexCommand \index{-mhc08}
4894 Generate code for the Motorola HC08
4895 \begin_inset LatexCommand \index{HC08}
4899 family of processors (added Oct 2003).
4901 \labelwidthstring 00.00.0000
4906 \begin_inset LatexCommand \index{-mz80}
4912 Generate code for the Zilog Z80
4913 \begin_inset LatexCommand \index{Z80}
4917 family of processors.
4919 \labelwidthstring 00.00.0000
4924 \begin_inset LatexCommand \index{-mgbz80}
4930 Generate code for the GameBoy Z80
4931 \begin_inset LatexCommand \index{gbz80 (GameBoy Z80)}
4935 processor (Not actively maintained).
4937 \labelwidthstring 00.00.0000
4942 \begin_inset LatexCommand \index{-mavr}
4948 Generate code for the Atmel AVR
4949 \begin_inset LatexCommand \index{AVR}
4953 processor (In development, not complete).
4954 AVR users should probably have a look at avr-gcc
4955 \begin_inset LatexCommand \url{ http://savannah.nongnu.org/download/avr-libc/snapshots/}
4962 I think it is fair to direct users there for now.
4963 Open source is also about avoiding unnecessary work .
4964 But I didn't find the 'official' link.
4966 \labelwidthstring 00.00.0000
4971 \begin_inset LatexCommand \index{-mpic14}
4977 Generate code for the Microchip PIC 14
4978 \begin_inset LatexCommand \index{PIC14}
4982 -bit processors (p16f84 and variants.
4983 In development, not complete).
4986 p16f627 p16f628 p16f84 p16f873 p16f877?
4988 \labelwidthstring 00.00.0000
4993 \begin_inset LatexCommand \index{-mpic16}
4999 Generate code for the Microchip PIC 16
5000 \begin_inset LatexCommand \index{PIC16}
5004 -bit processors (p18f452 and variants.
5005 In development, not complete).
5007 \labelwidthstring 00.00.0000
5013 Generate code for the Toshiba TLCS-900H
5014 \begin_inset LatexCommand \index{TLCS-900H}
5018 processor (Not maintained, not complete).
5020 \labelwidthstring 00.00.0000
5025 \begin_inset LatexCommand \index{-mxa51}
5031 Generate code for the Phillips XA51
5032 \begin_inset LatexCommand \index{XA51}
5036 processor (Not maintained, not complete).
5039 Preprocessor Options
5040 \begin_inset LatexCommand \index{Options preprocessor}
5045 \begin_inset LatexCommand \index{Preprocessor options}
5050 \begin_inset LatexCommand \index{sdcpp (preprocessor)}
5056 \labelwidthstring 00.00.0000
5061 \begin_inset LatexCommand \index{-I<path>}
5067 The additional location where the pre processor will look for <..h> or
5068 \begin_inset Quotes eld
5072 \begin_inset Quotes erd
5077 \labelwidthstring 00.00.0000
5082 \begin_inset LatexCommand \index{-D<macro[=value]>}
5088 Command line definition of macros.
5089 Passed to the preprocessor.
5091 \labelwidthstring 00.00.0000
5096 \begin_inset LatexCommand \index{-M}
5102 Tell the preprocessor to output a rule suitable for make describing the
5103 dependencies of each object file.
5104 For each source file, the preprocessor outputs one make-rule whose target
5105 is the object file name for that source file and whose dependencies are
5106 all the files `#include'd in it.
5107 This rule may be a single line or may be continued with `
5109 '-newline if it is long.
5110 The list of rules is printed on standard output instead of the preprocessed
5113 \begin_inset LatexCommand \index{-E}
5119 \labelwidthstring 00.00.0000
5124 \begin_inset LatexCommand \index{-C}
5130 Tell the preprocessor not to discard comments.
5131 Used with the `-E' option.
5133 \labelwidthstring 00.00.0000
5138 \begin_inset LatexCommand \index{-MM}
5149 Like `-M' but the output mentions only the user header files included with
5151 \begin_inset Quotes eld
5155 System header files included with `#include <file>' are omitted.
5157 \labelwidthstring 00.00.0000
5162 \begin_inset LatexCommand \index{-Aquestion(answer)}
5168 Assert the answer answer for question, in case it is tested with a preprocessor
5169 conditional such as `#if #question(answer)'.
5170 `-A-' disables the standard assertions that normally describe the target
5173 \labelwidthstring 00.00.0000
5178 \begin_inset LatexCommand \index{-Umacro}
5184 Undefine macro macro.
5185 `-U' options are evaluated after all `-D' options, but before any `-include'
5186 and `-imacros' options.
5188 \labelwidthstring 00.00.0000
5193 \begin_inset LatexCommand \index{-dM}
5199 Tell the preprocessor to output only a list of the macro definitions that
5200 are in effect at the end of preprocessing.
5201 Used with the `-E' option.
5203 \labelwidthstring 00.00.0000
5208 \begin_inset LatexCommand \index{-dD}
5214 Tell the preprocessor to pass all macro definitions into the output, in
5215 their proper sequence in the rest of the output.
5217 \labelwidthstring 00.00.0000
5222 \begin_inset LatexCommand \index{-dN}
5233 Like `-dD' except that the macro arguments and contents are omitted.
5234 Only `#define name' is included in the output.
5236 \labelwidthstring 00.00.0000
5241 preprocessorOption[,preprocessorOption]
5244 \begin_inset LatexCommand \index{-Wp preprocessorOption[,preprocessorOption]}
5249 Pass the preprocessorOption to the preprocessor
5254 \begin_inset LatexCommand \index{sdcpp (preprocessor)}
5259 SDCC uses an adapted version of the preprocessor cpp of the GNU Compiler
5260 Collection (gcc), if you need more dedicated options please refer to the
5262 \begin_inset LatexCommand \htmlurl{http://www.gnu.org/software/gcc/onlinedocs/}
5270 \begin_inset LatexCommand \index{Options linker}
5275 \begin_inset LatexCommand \index{Linker options}
5281 \labelwidthstring 00.00.0000
5301 \begin_inset LatexCommand \index{-\/-lib-path <path>}
5306 \begin_inset LatexCommand \index{-L -\/-lib-path}
5313 <absolute path to additional libraries> This option is passed to the linkage
5314 editor's additional libraries
5315 \begin_inset LatexCommand \index{Libraries}
5320 The path name must be absolute.
5321 Additional library files may be specified in the command line.
5322 See section Compiling programs for more details.
5324 \labelwidthstring 00.00.0000
5341 \begin_inset LatexCommand \index{-\/-xram-loc <Value>}
5346 <Value> The start location of the external ram
5347 \begin_inset LatexCommand \index{xdata (mcs51, ds390 storage class)}
5351 , default value is 0.
5352 The value entered can be in Hexadecimal or Decimal format, e.g.: -
5362 -xram-loc 0x8000 or -
5374 \labelwidthstring 00.00.0000
5391 \begin_inset LatexCommand \index{-\/-code-loc <Value>}
5396 <Value> The start location of the code
5397 \begin_inset LatexCommand \index{code}
5401 segment, default value 0.
5402 Note when this option is used the interrupt vector table is also relocated
5403 to the given address.
5404 The value entered can be in Hexadecimal or Decimal format, e.g.: -
5414 -code-loc 0x8000 or -
5426 \labelwidthstring 00.00.0000
5443 \begin_inset LatexCommand \index{-\/-stack-loc <Value>}
5448 <Value> By default the stack
5449 \begin_inset LatexCommand \index{stack}
5453 is placed after the data segment.
5454 Using this option the stack can be placed anywhere in the internal memory
5456 The value entered can be in Hexadecimal or Decimal format, e.g.
5467 -stack-loc 0x20 or -
5478 Since the sp register is incremented before a push or call, the initial
5479 sp will be set to one byte prior the provided value.
5480 The provided value should not overlap any other memory areas such as used
5481 register banks or the data segment and with enough space for the current
5484 \labelwidthstring 00.00.0000
5501 \begin_inset LatexCommand \index{-\/-data-loc <Value>}
5506 <Value> The start location of the internal ram data
5507 \begin_inset LatexCommand \index{data (mcs51, ds390 storage class)}
5512 The value entered can be in Hexadecimal or Decimal format, eg.
5534 (By default, the start location of the internal ram data segment is set
5535 as low as possible in memory, taking into account the used register banks
5536 and the bit segment at address 0x20.
5537 For example if register banks 0 and 1 are used without bit variables, the
5538 data segment will be set, if -
5548 -data-loc is not used, to location 0x10.)
5550 \labelwidthstring 00.00.0000
5567 \begin_inset LatexCommand \index{-\/-idata-loc <Value>}
5572 <Value> The start location of the indirectly addressable internal ram
5573 \begin_inset LatexCommand \index{idata (mcs51, ds390 storage class)}
5577 of the 8051, default value is 0x80.
5578 The value entered can be in Hexadecimal or Decimal format, eg.
5589 -idata-loc 0x88 or -
5601 \labelwidthstring 00.00.0000
5618 <Value> The start location of the bit
5619 \begin_inset LatexCommand \index{bit}
5623 addressable internal ram of the 8051.
5629 Instead an option can be passed directly to the linker: -Wl\SpecialChar ~
5632 \labelwidthstring 00.00.0000
5647 \begin_inset LatexCommand \index{-\/-out-fmt-ihx}
5656 The linker output (final object code) is in Intel Hex format.
5657 \begin_inset LatexCommand \index{Intel hex format}
5661 This is the default option.
5662 The format itself is documented in the documentation of srecord
5663 \begin_inset LatexCommand \index{srecord (tool)}
5669 \labelwidthstring 00.00.0000
5684 \begin_inset LatexCommand \index{-\/-out-fmt-s19}
5693 The linker output (final object code) is in Motorola S19 format
5694 \begin_inset LatexCommand \index{Motorola S19 format}
5699 The format itself is documented in the documentation of srecord.
5701 \labelwidthstring 00.00.0000
5706 linkOption[,linkOption]
5709 \begin_inset LatexCommand \index{-Wl linkOption[,linkOption]}
5714 Pass the linkOption to the linker.
5715 See file sdcc/as/doc/asxhtm.html for more on linker options.
5719 \begin_inset LatexCommand \index{Options MCS51}
5724 \begin_inset LatexCommand \index{MCS51 options}
5730 \labelwidthstring 00.00.0000
5745 \begin_inset LatexCommand \index{-\/-model-small}
5756 Generate code for Small Model programs, see section Memory Models for more
5758 This is the default model.
5760 \labelwidthstring 00.00.0000
5775 \begin_inset LatexCommand \index{-\/-model-large}
5781 Generate code for Large model programs, see section Memory Models for more
5783 If this option is used all source files in the project have to be compiled
5786 \labelwidthstring 00.00.0000
5801 \begin_inset LatexCommand \index{-\/-xstack}
5807 Uses a pseudo stack in the first 256 bytes in the external ram for allocating
5808 variables and passing parameters.
5810 \begin_inset LatexCommand \ref{sub:External-Stack}
5815 External Stack for more details.
5817 \labelwidthstring 00.00.0000
5835 \begin_inset LatexCommand \index{-\/-iram-size <Value>}
5839 Causes the linker to check if the internal ram usage is within limits of
5842 \labelwidthstring 00.00.0000
5860 \begin_inset LatexCommand \index{-\/-xram-size <Value>}
5864 Causes the linker to check if the external ram usage is within limits of
5867 \labelwidthstring 00.00.0000
5885 \begin_inset LatexCommand \index{-\/-code-size <Value>}
5889 Causes the linker to check if the code memory usage is within limits of
5892 \labelwidthstring 00.00.0000
5910 \begin_inset LatexCommand \index{-\/-stack-size <Value>}
5914 Causes the linker to check if there is at minimum <Value> bytes for stack.
5916 \labelwidthstring 00.00.0000
5934 \begin_inset LatexCommand \index{-\/-pack-iram}
5938 Causes the linker use unused register banks for data variables or stack.
5941 DS390 / DS400 Options
5942 \begin_inset LatexCommand \index{Options DS390}
5947 \begin_inset LatexCommand \index{DS390 options}
5953 \labelwidthstring 00.00.0000
5970 \begin_inset LatexCommand \index{-\/-model-flat24}
5980 Generate 24-bit flat mode code.
5981 This is the one and only that the ds390 code generator supports right now
5982 and is default when using
5987 See section Memory Models for more details.
5989 \labelwidthstring 00.00.0000
6004 \begin_inset LatexCommand \index{-\/-protect-sp-update}
6010 disable interrupts during ESP:SP updates.
6012 \labelwidthstring 00.00.0000
6029 \begin_inset LatexCommand \index{-\/-stack-10bit}
6033 Generate code for the 10 bit stack mode of the Dallas DS80C390 part.
6034 This is the one and only that the ds390 code generator supports right now
6035 and is default when using
6040 In this mode, the stack is located in the lower 1K of the internal RAM,
6041 which is mapped to 0x400000.
6042 Note that the support is incomplete, since it still uses a single byte
6043 as the stack pointer.
6044 This means that only the lower 256 bytes of the potential 1K stack space
6045 will actually be used.
6046 However, this does allow you to reclaim the precious 256 bytes of low RAM
6047 for use for the DATA and IDATA segments.
6048 The compiler will not generate any code to put the processor into 10 bit
6050 It is important to ensure that the processor is in this mode before calling
6051 any re-entrant functions compiled with this option.
6052 In principle, this should work with the
6065 \begin_inset LatexCommand \index{-\/-stack-auto}
6071 option, but that has not been tested.
6072 It is incompatible with the
6085 \begin_inset LatexCommand \index{-\/-xstack}
6092 It also only makes sense if the processor is in 24 bit contiguous addressing
6105 -model-flat24 option
6109 \labelwidthstring 00.00.0000
6124 \begin_inset LatexCommand \index{-\/-stack-probe}
6130 insert call to function __stack_probe at each function prologue.
6132 \labelwidthstring 00.00.0000
6147 \begin_inset LatexCommand \index{-\/-tini-libid}
6153 <nnnn> LibraryID used in -mTININative.
6156 \labelwidthstring 00.00.0000
6171 \begin_inset LatexCommand \index{-\/-use-accelerator}
6177 generate code for DS390 Arithmetic Accelerator.
6182 \begin_inset LatexCommand \index{Options Z80}
6187 \begin_inset LatexCommand \index{Z80 options}
6193 \labelwidthstring 00.00.0000
6210 \begin_inset LatexCommand \index{-\/-callee-saves-bc}
6220 Force a called function to always save BC.
6222 \labelwidthstring 00.00.0000
6239 \begin_inset LatexCommand \index{-\/-no-std-crt0}
6243 When linking, skip the standard crt0.o object file.
6244 You must provide your own crt0.o for your system when linking.
6248 Optimization Options
6249 \begin_inset LatexCommand \index{Options optimization}
6254 \begin_inset LatexCommand \index{Optimization options}
6260 \labelwidthstring 00.00.0000
6275 \begin_inset LatexCommand \index{-\/-nogcse}
6281 Will not do global subexpression elimination, this option may be used when
6282 the compiler creates undesirably large stack/data spaces to store compiler
6284 A warning message will be generated when this happens and the compiler
6285 will indicate the number of extra bytes it allocated.
6286 It is recommended that this option NOT be used, #pragma\SpecialChar ~
6288 \begin_inset LatexCommand \index{\#pragma nogcse}
6292 can be used to turn off global subexpression elimination
6293 \begin_inset LatexCommand \index{Subexpression elimination}
6297 for a given function only.
6299 \labelwidthstring 00.00.0000
6314 \begin_inset LatexCommand \index{-\/-noinvariant}
6320 Will not do loop invariant optimizations, this may be turned off for reasons
6321 explained for the previous option.
6322 For more details of loop optimizations performed see section Loop Invariants.
6323 It is recommended that this option NOT be used, #pragma\SpecialChar ~
6325 \begin_inset LatexCommand \index{\#pragma noinvariant}
6329 can be used to turn off invariant optimizations for a given function only.
6331 \labelwidthstring 00.00.0000
6346 \begin_inset LatexCommand \index{-\/-noinduction}
6352 Will not do loop induction optimizations, see section strength reduction
6354 It is recommended that this option is NOT used, #pragma\SpecialChar ~
6356 \begin_inset LatexCommand \index{\#pragma noinduction}
6360 can be used to turn off induction optimizations for a given function only.
6362 \labelwidthstring 00.00.0000
6377 \begin_inset LatexCommand \index{-\/-nojtbound}
6388 Will not generate boundary condition check when switch statements
6389 \begin_inset LatexCommand \index{switch statement}
6393 are implemented using jump-tables.
6395 \begin_inset LatexCommand \ref{sub:'switch'-Statements}
6400 Switch Statements for more details.
6401 It is recommended that this option is NOT used, #pragma\SpecialChar ~
6403 \begin_inset LatexCommand \index{\#pragma nojtbound}
6407 can be used to turn off boundary checking for jump tables for a given function
6410 \labelwidthstring 00.00.0000
6425 \begin_inset LatexCommand \index{-\/-noloopreverse}
6434 Will not do loop reversal
6435 \begin_inset LatexCommand \index{Loop reversing}
6441 \labelwidthstring 00.00.0000
6458 \begin_inset LatexCommand \index{-\/-nolabelopt }
6462 Will not optimize labels (makes the dumpfiles more readable).
6464 \labelwidthstring 00.00.0000
6479 \begin_inset LatexCommand \index{-\/-no-xinit-opt}
6485 Will not memcpy initialized data from code space into xdata space.
6486 This saves a few bytes in code space if you don't have initialized data.
6488 \labelwidthstring 00.00.0000
6503 \begin_inset LatexCommand \index{-\/-nooverlay}
6509 The compiler will not overlay parameters and local variables of any function,
6510 see section Parameters and local variables for more details.
6512 \labelwidthstring 00.00.0000
6527 \begin_inset LatexCommand \index{-\/-no-peep}
6533 Disable peep-hole optimization.
6535 \labelwidthstring 00.00.0000
6552 \begin_inset LatexCommand \index{-\/-peep-file}
6557 <filename> This option can be used to use additional rules to be used by
6558 the peep hole optimizer.
6560 \begin_inset LatexCommand \ref{sub:Peephole-Optimizer}
6565 Peep Hole optimizations for details on how to write these rules.
6567 \labelwidthstring 00.00.0000
6582 \begin_inset LatexCommand \index{-\/-peep-asm}
6588 Pass the inline assembler code through the peep hole optimizer.
6589 This can cause unexpected changes to inline assembler code, please go through
6590 the peephole optimizer
6591 \begin_inset LatexCommand \index{Peephole optimizer}
6595 rules defined in the source file tree '<target>/peeph.def' before using
6600 \begin_inset LatexCommand \index{Options other}
6606 \labelwidthstring 00.00.0000
6622 \begin_inset LatexCommand \index{-\/-compile-only}
6627 \begin_inset LatexCommand \index{-c -\/-compile-only}
6633 will compile and assemble the source, but will not call the linkage editor.
6635 \labelwidthstring 00.00.0000
6654 \begin_inset LatexCommand \index{-\/-c1mode}
6660 reads the preprocessed source from standard input and compiles it.
6661 The file name for the assembler output must be specified using the -o option.
6663 \labelwidthstring 00.00.0000
6668 \begin_inset LatexCommand \index{-E}
6674 Run only the C preprocessor.
6675 Preprocess all the C source files specified and output the results to standard
6678 \labelwidthstring 00.00.0000
6684 \begin_inset LatexCommand \index{-o <path/file>}
6690 The output path resp.
6691 file where everything will be placed.
6692 If the parameter is a path, it must have a trailing slash (or backslash
6693 for the Windows binaries) to be recognized as a path.
6696 \labelwidthstring 00.00.0000
6711 \begin_inset LatexCommand \index{-\/-stack-auto}
6722 All functions in the source file will be compiled as
6727 \begin_inset LatexCommand \index{reentrant}
6732 the parameters and local variables will be allocated on the stack
6733 \begin_inset LatexCommand \index{stack}
6738 see section Parameters and Local Variables for more details.
6739 If this option is used all source files in the project should be compiled
6743 \labelwidthstring 00.00.0000
6758 \begin_inset LatexCommand \index{-\/-callee-saves}
6762 function1[,function2][,function3]....
6765 The compiler by default uses a caller saves convention for register saving
6766 across function calls, however this can cause unnecessary register pushing
6767 & popping when calling small functions from larger functions.
6768 This option can be used to switch the register saving convention for the
6769 function names specified.
6770 The compiler will not save registers when calling these functions, no extra
6771 code will be generated at the entry & exit (function prologue
6774 \begin_inset LatexCommand \index{function prologue}
6783 \begin_inset LatexCommand \index{function epilogue}
6789 ) for these functions to save & restore the registers used by these functions,
6790 this can SUBSTANTIALLY reduce code & improve run time performance of the
6792 In the future the compiler (with inter procedural analysis) will be able
6793 to determine the appropriate scheme to use for each function call.
6794 DO NOT use this option for built-in functions such as _mulint..., if this
6795 option is used for a library function the appropriate library function
6796 needs to be recompiled with the same option.
6797 If the project consists of multiple source files then all the source file
6798 should be compiled with the same -
6808 -callee-saves option string.
6809 Also see #pragma\SpecialChar ~
6811 \begin_inset LatexCommand \index{\#pragma callee\_saves}
6817 \labelwidthstring 00.00.0000
6832 \begin_inset LatexCommand \index{-\/-debug}
6841 When this option is used the compiler will generate debug information.
6842 The debug information collected in a file with .cdb extension can be used
6844 For more information see documentation for SDCDB.
6845 Another file with no extension contains debug information in AOMF or AOMF51
6846 \begin_inset LatexCommand \index{AOMF, AOMF51}
6850 format which is commonly used by third party tools.
6852 \labelwidthstring 00.00.0000
6857 \begin_inset LatexCommand \index{-S}
6868 Stop after the stage of compilation proper; do not assemble.
6869 The output is an assembler code file for the input file specified.
6871 \labelwidthstring 00.00.0000
6886 \begin_inset LatexCommand \index{-\/-int-long-reent}
6892 Integer (16 bit) and long (32 bit) libraries have been compiled as reentrant.
6893 Note by default these libraries are compiled as non-reentrant.
6894 See section Installation for more details.
6896 \labelwidthstring 00.00.0000
6911 \begin_inset LatexCommand \index{-\/-cyclomatic}
6920 This option will cause the compiler to generate an information message for
6921 each function in the source file.
6922 The message contains some
6926 information about the function.
6927 The number of edges and nodes the compiler detected in the control flow
6928 graph of the function, and most importantly the
6930 cyclomatic complexity
6931 \begin_inset LatexCommand \index{Cyclomatic complexity}
6937 see section on Cyclomatic Complexity for more details.
6939 \labelwidthstring 00.00.0000
6954 \begin_inset LatexCommand \index{-\/-float-reent}
6960 Floating point library is compiled as reentrant
6961 \begin_inset LatexCommand \index{reentrant}
6966 See section Installation for more details.
6968 \labelwidthstring 00.00.0000
6983 \begin_inset LatexCommand \index{-\/-main-return}
6989 This option can be used when the code generated is called by a monitor
6991 The compiler will generate a 'ret' upon return from the 'main'
6992 \begin_inset LatexCommand \index{main return}
6997 The default setting is to lock up i.e.
7004 \labelwidthstring 00.00.0000
7019 \begin_inset LatexCommand \index{-\/-nostdincl}
7025 This will prevent the compiler from passing on the default include path
7026 to the preprocessor.
7028 \labelwidthstring 00.00.0000
7043 \begin_inset LatexCommand \index{-\/-nostdlib}
7049 This will prevent the compiler from passing on the default library
7050 \begin_inset LatexCommand \index{Libraries}
7056 \labelwidthstring 00.00.0000
7071 \begin_inset LatexCommand \index{-\/-verbose}
7077 Shows the various actions the compiler is performing.
7079 \labelwidthstring 00.00.0000
7084 \begin_inset LatexCommand \index{-V}
7090 Shows the actual commands the compiler is executing.
7092 \labelwidthstring 00.00.0000
7107 \begin_inset LatexCommand \index{-\/-no-c-code-in-asm}
7113 Hides your ugly and inefficient c-code from the asm file, so you can always
7114 blame the compiler :).
7116 \labelwidthstring 00.00.0000
7131 \begin_inset LatexCommand \index{-\/-i-code-in-asm}
7137 Include i-codes in the asm file.
7138 Sounds like noise but is most helpful for debugging the compiler itself.
7140 \labelwidthstring 00.00.0000
7155 \begin_inset LatexCommand \index{-\/-less-pedantic}
7161 Disable some of the more pedantic warnings
7162 \begin_inset LatexCommand \index{Warnings}
7166 (jwk burps: please be more specific here, please!).
7167 If you want rather more than less warnings you should consider using a
7168 separate tool dedicated to syntax checking like splint
7169 \begin_inset LatexCommand \url{www.splint.org}
7175 \labelwidthstring 00.00.0000
7190 \begin_inset LatexCommand \index{-\/-print-search-dirs}
7196 Display the directories in the compiler's search path
7198 \labelwidthstring 00.00.0000
7213 \begin_inset LatexCommand \index{-\/-vc}
7219 Display errors and warnings using MSVC style, so you can use SDCC with
7222 \labelwidthstring 00.00.0000
7237 \begin_inset LatexCommand \index{-\/-use-stdout}
7243 Send errors and warnings to stdout instead of stderr.
7245 \labelwidthstring 00.00.0000
7250 asmOption[,asmOption]
7253 \begin_inset LatexCommand \index{-Wa asmOption[,asmOption]}
7258 Pass the asmOption to the assembler
7259 \begin_inset LatexCommand \index{Options assembler}
7264 \begin_inset LatexCommand \index{Assembler options}
7269 See file sdcc/as/doc/asxhtm.html for assembler options.
7272 Intermediate Dump Options
7273 \begin_inset LatexCommand \label{sub:Intermediate-Dump-Options}
7278 \begin_inset LatexCommand \index{Options intermediate dump}
7283 \begin_inset LatexCommand \index{Intermediate dump options}
7290 The following options are provided for the purpose of retargetting and debugging
7292 These provided a means to dump the intermediate code (iCode
7293 \begin_inset LatexCommand \index{iCode}
7297 ) generated by the compiler in human readable form at various stages of
7298 the compilation process.
7299 More on iCodes see chapter
7300 \begin_inset LatexCommand \ref{sub:The-anatomy-of}
7305 \begin_inset Quotes srd
7308 The anatomy of the compiler
7309 \begin_inset Quotes srd
7314 \labelwidthstring 00.00.0000
7329 \begin_inset LatexCommand \index{-\/-dumpraw}
7335 This option will cause the compiler to dump the intermediate code into
7338 <source filename>.dumpraw
7340 just after the intermediate code has been generated for a function, i.e.
7341 before any optimizations are done.
7343 \begin_inset LatexCommand \index{Basic blocks}
7347 at this stage ordered in the depth first number, so they may not be in
7348 sequence of execution.
7350 \labelwidthstring 00.00.0000
7365 \begin_inset LatexCommand \index{-\/-dumpgcse}
7371 Will create a dump of iCode's, after global subexpression elimination
7372 \begin_inset LatexCommand \index{Global subexpression elimination}
7378 <source filename>.dumpgcse.
7380 \labelwidthstring 00.00.0000
7395 \begin_inset LatexCommand \index{-\/-dumpdeadcode}
7401 Will create a dump of iCode's, after deadcode elimination
7402 \begin_inset LatexCommand \index{Dead-code elimination}
7408 <source filename>.dumpdeadcode.
7410 \labelwidthstring 00.00.0000
7425 \begin_inset LatexCommand \index{-\/-dumploop}
7434 Will create a dump of iCode's, after loop optimizations
7435 \begin_inset LatexCommand \index{Loop optimization}
7441 <source filename>.dumploop.
7443 \labelwidthstring 00.00.0000
7458 \begin_inset LatexCommand \index{-\/-dumprange}
7467 Will create a dump of iCode's, after live range analysis
7468 \begin_inset LatexCommand \index{Live range analysis}
7474 <source filename>.dumprange.
7476 \labelwidthstring 00.00.0000
7491 \begin_inset LatexCommand \index{-\/-dumlrange}
7497 Will dump the life ranges
7498 \begin_inset LatexCommand \index{Live range analysis}
7504 \labelwidthstring 00.00.0000
7519 \begin_inset LatexCommand \index{-\/-dumpregassign}
7528 Will create a dump of iCode's, after register assignment
7529 \begin_inset LatexCommand \index{Register assignment}
7535 <source filename>.dumprassgn.
7537 \labelwidthstring 00.00.0000
7552 \begin_inset LatexCommand \index{-\/-dumplrange}
7558 Will create a dump of the live ranges of iTemp's
7560 \labelwidthstring 00.00.0000
7575 \begin_inset LatexCommand \index{-\/-dumpall}
7586 Will cause all the above mentioned dumps to be created.
7589 Redirecting output on Windows Shells
7592 By default SDCC writes it's error messages to
7593 \begin_inset Quotes sld
7597 \begin_inset Quotes srd
7601 To force all messages to
7602 \begin_inset Quotes sld
7606 \begin_inset Quotes srd
7630 \begin_inset LatexCommand \index{-\/-use-stdout}
7635 Additionally, if you happen to have visual studio installed in your windows
7636 machine, you can use it to compile your sources using a custom build and
7652 \begin_inset LatexCommand \index{-\/-vc}
7657 Something like this should work:
7701 -model-large -c $(InputPath)
7704 Environment variables
7705 \begin_inset LatexCommand \index{Environment variables}
7712 SDCC recognizes the following environment variables:
7714 \labelwidthstring 00.00.0000
7719 \begin_inset LatexCommand \index{SDCC\_LEAVE\_SIGNALS}
7725 SDCC installs a signal handler
7726 \begin_inset LatexCommand \index{signal handler}
7730 to be able to delete temporary files after an user break (^C) or an exception.
7731 If this environment variable is set, SDCC won't install the signal handler
7732 in order to be able to debug SDCC.
7734 \labelwidthstring 00.00.0000
7741 \begin_inset LatexCommand \index{TMP, TEMP, TMPDIR}
7747 Path, where temporary files will be created.
7748 The order of the variables is the search order.
7749 In a standard *nix environment these variables are not set, and there's
7750 no need to set them.
7751 On Windows it's recommended to set one of them.
7753 \labelwidthstring 00.00.0000
7758 \begin_inset LatexCommand \index{SDCC\_HOME}
7765 \begin_inset LatexCommand \ref{sub:Install-paths}
7771 \begin_inset Quotes sld
7775 \begin_inset Quotes srd
7780 \labelwidthstring 00.00.0000
7785 \begin_inset LatexCommand \index{SDCC\_INCLUDE}
7792 \begin_inset LatexCommand \ref{sub:Search-Paths}
7798 \begin_inset Quotes sld
7802 \begin_inset Quotes srd
7807 \labelwidthstring 00.00.0000
7812 \begin_inset LatexCommand \index{SDCC\_LIB}
7819 \begin_inset LatexCommand \ref{sub:Search-Paths}
7825 \begin_inset Quotes sld
7829 \begin_inset Quotes srd
7835 There are some more environment variables recognized by SDCC, but these
7836 are solely used for debugging purposes.
7837 They can change or disappear very quickly, and will never be documented.
7840 Storage Class Language Extensions
7843 MCS51/DS390 Storage Class
7844 \begin_inset LatexCommand \index{Storage class}
7851 In addition to the ANSI storage classes SDCC allows the following MCS51
7852 specific storage classes:
7853 \layout Subsubsection
7856 \begin_inset LatexCommand \index{data (mcs51, ds390 storage class)}
7861 \begin_inset LatexCommand \index{near (storage class)}
7872 storage class for the Small Memory model (
7880 can be used synonymously).
7881 Variables declared with this storage class will be allocated in the directly
7882 addressable portion of the internal RAM of a 8051, e.g.:
7887 data unsigned char test_data;
7890 Writing 0x01 to this variable generates the assembly code:
7895 75*00 01\SpecialChar ~
7901 \layout Subsubsection
7904 \begin_inset LatexCommand \index{xdata (mcs51, ds390 storage class)}
7909 \begin_inset LatexCommand \index{far (storage class)}
7916 Variables declared with this storage class will be placed in the external
7922 storage class for the Large Memory model, e.g.:
7927 xdata unsigned char test_xdata;
7930 Writing 0x01 to this variable generates the assembly code:
7935 90s00r00\SpecialChar ~
7964 \layout Subsubsection
7967 \begin_inset LatexCommand \index{idata (mcs51, ds390 storage class)}
7974 Variables declared with this storage class will be allocated into the indirectly
7975 addressable portion of the internal ram of a 8051, e.g.:
7980 idata unsigned char test_idata;
7983 Writing 0x01 to this variable generates the assembly code:
8012 Please note, the first 128 byte of idata physically access the same RAM
8014 The original 8051 had 128 byte idata memory, nowadays most devices have
8015 256 byte idata memory.
8017 \begin_inset LatexCommand \index{stack}
8021 is located in idata memory.
8022 \layout Subsubsection
8025 \begin_inset LatexCommand \index{pdata (mcs51, ds390 storage class)}
8032 Paged xdata access is currently not as straightforward as using the other
8033 addressing modes of a 8051.
8034 The following example writes 0x01 to the address pointed to.
8035 Please note, pdata access physically accesses xdata memory.
8036 The high byte of the address is determined by port P2
8037 \begin_inset LatexCommand \index{P2 (mcs51 sfr)}
8041 (or in case of some 8051 variants by a separate Special Function Register,
8043 \begin_inset LatexCommand \ref{sub:MCS51-variants}
8052 pdata unsigned char *test_pdata_ptr;
8064 test_pdata_ptr = (pdata *)0xfe;
8070 *test_pdata_ptr = 1;
8075 Generates the assembly code:
8080 75*01 FE\SpecialChar ~
8084 _test_pdata_ptr,#0xFE
8116 Be extremely carefull if you use pdata together with the -
8127 \begin_inset LatexCommand \index{-\/-xstack}
8132 \layout Subsubsection
8135 \begin_inset LatexCommand \index{code}
8142 'Variables' declared with this storage class will be placed in the code
8148 code unsigned char test_code;
8151 Read access to this variable generates the assembly code:
8156 90s00r6F\SpecialChar ~
8159 mov dptr,#_test_code
8188 indexed arrays of characters in code memory can be accessed efficiently:
8193 code char test_array[] = {'c','h','e','a','p'};
8196 Read access to this array using an 8-bit unsigned index generates the assembly
8213 90s00r41\SpecialChar ~
8216 mov dptr,#_test_array
8231 \layout Subsubsection
8234 \begin_inset LatexCommand \index{bit}
8241 This is a data-type and a storage class specifier.
8242 When a variable is declared as a bit, it is allocated into the bit addressable
8243 memory of 8051, e.g.:
8251 Writing 1 to this variable generates the assembly code:
8267 The bit addressable memory consists of 128 bits which are located from 0x20
8268 to 0x2f in data memory.
8272 Apart from this 8051 specific storage class most architectures support ANSI-C
8274 \begin_inset LatexCommand \index{bitfields}
8284 Not really meant as examples, but nevertheless showing what bitfields are
8285 about: device/include/mc68hc908qy.h and support/regression/tests/bitfields.c
8289 \layout Subsubsection
8292 \begin_inset LatexCommand \index{sfr}
8297 \begin_inset LatexCommand \index{sbit}
8304 Like the bit keyword,
8308 signifies both a data-type and storage class, they are used to describe
8329 variables of a 8051, eg:
8335 \begin_inset LatexCommand \index{at}
8339 0x80 P0;\SpecialChar ~
8340 /* special function register P0 at location 0x80 */
8342 sbit at 0xd7 CY; /* CY (Carry Flag
8343 \begin_inset LatexCommand \index{Flags}
8348 \begin_inset LatexCommand \index{Carry flag}
8355 Special function registers which are located on an address dividable by
8356 8 are bit-addressable, an
8360 addresses a specific bit within these sfr.
8361 \layout Subsubsection
8364 \begin_inset LatexCommand \index{Pointer}
8368 to MCS51/DS390 specific memory spaces
8371 SDCC allows (via language extensions) pointers to explicitly point to any
8372 of the memory spaces
8373 \begin_inset LatexCommand \index{Memory model}
8378 In addition to the explicit pointers, the compiler uses (by default) generic
8379 pointers which can be used to point to any of the memory spaces.
8383 Pointer declaration examples:
8388 /* pointer physically in internal ram pointing to object in external ram
8391 xdata unsigned char * data p;
8395 /* pointer physically in external ram pointing to object in internal ram
8398 data unsigned char * xdata p;
8402 /* pointer physically in code rom pointing to data in xdata space */
8404 xdata unsigned char * code p;
8408 /* pointer physically in code space pointing to data in code space */
8410 code unsigned char * code p;
8414 /* the following is a generic pointer physically located in xdata space
8420 Well you get the idea.
8425 All unqualified pointers are treated as 3-byte (4-byte for the ds390)
8438 The highest order byte of the
8442 pointers contains the data space information.
8443 Assembler support routines are called whenever data is stored or retrieved
8449 These are useful for developing reusable library
8450 \begin_inset LatexCommand \index{Libraries}
8455 Explicitly specifying the pointer type will generate the most efficient
8457 \layout Subsubsection
8459 Notes on MCS51 memory
8460 \begin_inset LatexCommand \index{MCS51 memory}
8467 The 8051 family of microcontrollers have a minimum of 128 bytes of internal
8468 RAM memory which is structured as follows:
8472 - Bytes 00-1F - 32 bytes to hold up to 4 banks of the registers R0 to R7,
8475 - Bytes 20-2F - 16 bytes to hold 128 bit
8476 \begin_inset LatexCommand \index{bit}
8482 - Bytes 30-7F - 80 bytes for general purpose use.
8487 Additionally some members of the MCS51 family may have up to 128 bytes of
8488 additional, indirectly addressable, internal RAM memory (
8493 \begin_inset LatexCommand \index{idata (mcs51, ds390 storage class)}
8498 Furthermore, some chips may have some built in external memory (
8503 \begin_inset LatexCommand \index{xdata (mcs51, ds390 storage class)}
8507 ) which should not be confused with the internal, directly addressable RAM
8513 \begin_inset LatexCommand \index{data (mcs51, ds390 storage class)}
8518 Sometimes this built in
8522 memory has to be activated before using it (you can probably find this
8523 information on the datasheet of the microcontroller your are using, see
8525 \begin_inset LatexCommand \ref{sub:Startup-Code}
8533 Normally SDCC will only use the first bank
8534 \begin_inset LatexCommand \index{register bank (mcs51, ds390)}
8538 of registers (register bank 0), but it is possible to specify that other
8539 banks of registers should be used in interrupt
8540 \begin_inset LatexCommand \index{interrupt}
8545 By default, the compiler will place the stack after the last byte of allocated
8546 memory for variables.
8547 For example, if the first 2 banks of registers are used, and only four
8552 variables, it will position the base of the internal stack at address 20
8554 This implies that as the stack
8555 \begin_inset LatexCommand \index{stack}
8559 grows, it will use up the remaining register banks, and the 16 bytes used
8560 by the 128 bit variables, and 80 bytes for general purpose use.
8561 If any bit variables are used, the data variables will be placed after
8562 the byte holding the last bit variable.
8563 For example, if register banks 0 and 1 are used, and there are 9 bit variables
8568 variables will be placed starting at address 0x22.
8580 \begin_inset LatexCommand \index{-\/-data-loc<Value>}
8584 to specify the start address of the
8598 -iram-size to specify the size of the total internal RAM (
8610 By default the 8051 linker will place the stack after the last byte of data
8623 \begin_inset LatexCommand \index{-\/-stack-loc<Value>}
8627 allows you to specify the start of the stack, i.e.
8628 you could start it after any data in the general purpose area.
8629 If your microcontroller has additional indirectly addressable internal
8634 ) you can place the stack on it.
8635 You may also need to use -
8646 \begin_inset LatexCommand \index{-\/-xdata-loc<Value>}
8650 to set the start address of the external RAM (
8665 \begin_inset LatexCommand \index{-\/-data-loc}
8669 to specify its size.
8670 Same goes for the code memory, using -
8681 \begin_inset LatexCommand \index{-\/-data-loc}
8696 \begin_inset LatexCommand \index{-\/-data-loc}
8701 If in doubt, don't specify any options and see if the resulting memory
8702 layout is appropriate, then you can adjust it.
8705 The linker generates two files with memory allocation information.
8706 The first, with extension .map
8707 \begin_inset LatexCommand \index{<file>.map}
8711 shows all the variables and segments.
8712 The second with extension .mem
8713 \begin_inset LatexCommand \index{<file>.mem}
8717 shows the final memory layout.
8718 The linker will complain either if memory segments overlap, there is not
8719 enough memory, or there is not enough space for stack.
8720 If you get any linking warnings and/or errors related to stack or segments
8721 allocation, take a look at either the .map or .mem files to find out what
8723 The .mem file may even suggest a solution to the problem.
8726 Z80/Z180 Storage Class
8727 \begin_inset LatexCommand \index{Storage class}
8732 \layout Subsubsection
8735 \begin_inset LatexCommand \index{sfr}
8739 (in/out to 8-bit addresses)
8743 \begin_inset LatexCommand \index{Z80}
8747 family has separate address spaces for memory and
8757 \begin_inset LatexCommand \index{I/O memory (Z80, Z180)}
8761 is accessed with special instructions, e.g.:
8766 sfr at 0x78 IoPort;\SpecialChar ~
8768 /* define a var in I/O space at 78h called IoPort */
8772 Writing 0x01 to this variable generates the assembly code:
8792 \layout Subsubsection
8795 \begin_inset LatexCommand \index{sfr}
8799 (in/out to 16-bit addresses)
8806 is used to support 16 bit addresses in I/O memory e.g.:
8812 \begin_inset LatexCommand \index{at}
8819 Writing 0x01 to this variable generates the assembly code:
8824 01 23 01\SpecialChar ~
8844 \layout Subsubsection
8847 \begin_inset LatexCommand \index{sfr}
8851 (in0/out0 to 8 bit addresses on Z180
8852 \begin_inset LatexCommand \index{Z180}
8857 \begin_inset LatexCommand \index{HD64180}
8864 The compiler option -
8874 -portmode=180 (80) and a compiler #pragma\SpecialChar ~
8876 \begin_inset LatexCommand \index{\#pragma portmode}
8880 =z180 (z80) is used to turn on (off) the Z180/HD64180 port addressing instructio
8890 If you include the file z180.h this will be set automatically.
8894 \begin_inset LatexCommand \index{Storage class}
8899 \layout Subsubsection
8902 \begin_inset LatexCommand \index{data (mcs51, ds390 storage class)}
8909 The data storage class declares a variable that resides in the first 256
8910 bytes of memory (the direct page).
8911 The HC08 is most efficient at accessing variables (especially pointers)
8913 \layout Subsubsection
8916 \begin_inset LatexCommand \index{xdata (mcs51, ds390 storage class)}
8923 The xdata storage class declares a variable that can reside anywhere in
8925 This is the default if no storage class is specified.
8930 \begin_inset LatexCommand \index{Absolute addressing}
8937 Data items can be assigned an absolute address with the
8940 \begin_inset LatexCommand \index{at}
8946 keyword, in addition to a storage class, e.g.:
8952 \begin_inset LatexCommand \index{xdata (mcs51, ds390 storage class)}
8957 \begin_inset LatexCommand \index{at}
8961 0x7ffe unsigned int chksum;
8964 In the above example the variable chksum will located at 0x7ffe and 0x7fff
8965 of the external ram.
8970 reserve any space for variables declared in this way (they are implemented
8971 with an equate in the assembler).
8972 Thus it is left to the programmer to make sure there are no overlaps with
8973 other variables that are declared without the absolute address.
8974 The assembler listing file (.lst
8975 \begin_inset LatexCommand \index{<file>.lst}
8979 ) and the linker output files (.rst
8980 \begin_inset LatexCommand \index{<file>.rst}
8985 \begin_inset LatexCommand \index{<file>.map}
8989 ) are good places to look for such overlaps.
8990 Variables with an absolute address are
8995 \begin_inset LatexCommand \index{Variable initialization}
9002 In case of memory mapped I/O devices the keyword
9006 should be used to tell the compiler that accesses might not be optimized
9013 \begin_inset LatexCommand \index{volatile}
9018 \begin_inset LatexCommand \index{xdata (mcs51, ds390 storage class)}
9023 \begin_inset LatexCommand \index{at}
9027 0x8000 unsigned char PORTA_8255;
9030 For some architectures (mcs51) array accesses are more efficient if an (xdata/fa
9035 \begin_inset LatexCommand \index{Aligned array}
9042 starts at a block (256 byte) boundary
9043 \begin_inset LatexCommand \index{block boundary}
9048 \begin_inset LatexCommand \ref{sub:A-Step-by Assembler Introduction}
9054 Absolute addresses can be specified for variables in all storage classes,
9061 \begin_inset LatexCommand \index{bit}
9066 \begin_inset LatexCommand \index{at}
9073 The above example will allocate the variable at offset 0x02 in the bit-addressab
9075 There is no real advantage to assigning absolute addresses to variables
9076 in this manner, unless you want strict control over all the variables allocated.
9077 One possible use would be to write hardware portable code.
9078 For example, if you have a routine that uses one or more of the microcontroller
9079 I/O pins, and such pins are different for two different hardwares, you
9080 can declare the I/O pins in your routine using:
9085 extern volatile bit SDI;
9087 extern volatile bit SCLK;
9089 extern volatile bit CPOL;
9093 void DS1306_put(unsigned char value)
9101 unsigned char mask=0x80;
9125 SDI=(value & mask)?1:0;
9166 Then, someplace in the code for the first hardware you would use
9171 bit at 0x80 SDI;\SpecialChar ~
9175 /* I/O port 0, bit 0 */
9177 bit at 0x81 SCLK;\SpecialChar ~
9180 /* I/O port 0, bit 1 */
9182 bit CPOL;\SpecialChar ~
9193 /* This is a variable, let the linker allocate this one */
9196 Similarly, for the second hardware you would use
9201 bit at 0x83 SDI;\SpecialChar ~
9205 /* I/O port 0, bit 3 */
9207 bit at 0x91 SCLK;\SpecialChar ~
9210 /* I/O port 1, bit 1 */
9213 \begin_inset LatexCommand \index{bit}
9228 /* This is a variable, let the linker allocate this one */
9231 and you can use the same hardware dependent routine without changes, as
9232 for example in a library.
9233 This is somehow similar to sbit, but only one absolute address has to be
9234 specified in the whole project.
9238 \begin_inset LatexCommand \index{Parameters}
9243 \begin_inset LatexCommand \index{function parameter}
9248 \begin_inset LatexCommand \index{local variables}
9255 Automatic (local) variables and parameters to functions can either be placed
9256 on the stack or in data-space.
9257 The default action of the compiler is to place these variables in the internal
9258 RAM (for small model) or external RAM (for large model).
9259 This in fact makes them similar to
9262 \begin_inset LatexCommand \index{static}
9268 so by default functions are non-reentrant
9269 \begin_inset LatexCommand \index{reentrant}
9278 They can be placed on the stack
9279 \begin_inset LatexCommand \index{stack}
9296 \begin_inset LatexCommand \index{-\/-stack-auto}
9302 option or by using the
9305 \begin_inset LatexCommand \index{reentrant}
9311 keyword in the function declaration, e.g.:
9316 unsigned char foo(char i) reentrant
9330 Since stack space on 8051 is limited, the
9348 option should be used sparingly.
9349 Note that the reentrant keyword just means that the parameters & local
9350 variables will be allocated to the stack, it
9354 mean that the function is register bank
9355 \begin_inset LatexCommand \index{register bank (mcs51, ds390)}
9364 \begin_inset LatexCommand \index{local variables}
9368 can be assigned storage classes and absolute
9369 \begin_inset LatexCommand \index{Absolute addressing}
9386 xdata unsigned char i;
9399 \begin_inset LatexCommand \index{at}
9403 0x31 unsigned char j;
9415 In the above example the variable
9419 will be allocated in the external ram,
9423 in bit addressable space and
9442 or when a function is declared as
9446 this should only be done for static variables.
9450 \begin_inset LatexCommand \index{function parameter}
9454 however are not allowed any storage class
9455 \begin_inset LatexCommand \index{Storage class}
9459 , (storage classes for parameters will be ignored), their allocation is
9460 governed by the memory model in use, and the reentrancy options.
9464 \begin_inset LatexCommand \label{sub:Overlaying}
9469 \begin_inset LatexCommand \index{Overlaying}
9477 \begin_inset LatexCommand \index{reentrant}
9481 functions SDCC will try to reduce internal ram space usage by overlaying
9482 parameters and local variables of a function (if possible).
9483 Parameters and local variables
9484 \begin_inset LatexCommand \index{local variables}
9488 of a function will be allocated to an overlayable segment if the function
9491 no other function calls and the function is non-reentrant and the memory
9493 \begin_inset LatexCommand \index{Memory model}
9500 If an explicit storage class
9501 \begin_inset LatexCommand \index{Storage class}
9505 is specified for a local variable, it will NOT be overlayed.
9508 Note that the compiler (not the linkage editor) makes the decision for overlayin
9510 Functions that are called from an interrupt service routine should be preceded
9511 by a #pragma\SpecialChar ~
9513 \begin_inset LatexCommand \index{\#pragma nooverlay}
9517 if they are not reentrant.
9520 Also note that the compiler does not do any processing of inline assembler
9521 code, so the compiler might incorrectly assign local variables and parameters
9522 of a function into the overlay segment if the inline assembler code calls
9523 other c-functions that might use the overlay.
9524 In that case the #pragma\SpecialChar ~
9525 nooverlay should be used.
9528 Parameters and local variables of functions that contain 16 or 32 bit multiplica
9530 \begin_inset LatexCommand \index{Multiplication}
9535 \begin_inset LatexCommand \index{Division}
9539 will NOT be overlayed since these are implemented using external functions,
9548 \begin_inset LatexCommand \index{\#pragma nooverlay}
9554 void set_error(unsigned char errcd)
9570 void some_isr () interrupt
9571 \begin_inset LatexCommand \index{interrupt}
9601 In the above example the parameter
9609 would be assigned to the overlayable segment if the #pragma\SpecialChar ~
9611 not present, this could cause unpredictable runtime behavior when called
9612 from an interrupt service routine.
9613 The #pragma\SpecialChar ~
9614 nooverlay ensures that the parameters and local variables for
9615 the function are NOT overlayed.
9618 Interrupt Service Routines
9619 \begin_inset LatexCommand \label{sub:Interrupt-Service-Routines}
9641 outines to be coded in C, with some extended keywords.
9646 void timer_isr (void) interrupt 1 using 1
9660 The optional number following the
9663 \begin_inset LatexCommand \index{interrupt}
9669 keyword is the interrupt number this routine will service.
9670 When present, the compiler will insert a call to this routine in the interrupt
9671 vector table for the interrupt number specified.
9672 If you have multiple source files in your project, interrupt service routines
9673 can be present in any of them, but a prototype of the isr MUST be present
9674 or included in the file that contains the function
9683 keyword can be used to tell the compiler to use the specified register
9684 bank (8051 specific) when generating code for this function.
9690 Interrupt service routines open the door for some very interesting bugs:
9694 If the interrupt service routines changes variables which are accessed by
9695 other functions these variables should be declared
9700 \begin_inset LatexCommand \index{volatile}
9708 If the access to these variables is not
9711 \begin_inset LatexCommand \index{atomic access}
9718 the processor needs more than one instruction for the access and could
9719 be interrupted while accessing the variable) the interrupt must disabled
9720 during the access to avoid inconsistent data.
9721 Access to 16 or 32 bit variables is obviously not atomic on 8 bit CPUs
9722 and should be protected by disabling interrupts.
9723 You're not automatically on the safe side if you use 8 bit variables though.
9724 We need an example here: f.e.
9725 on the 8051 the harmless looking
9726 \begin_inset Quotes srd
9736 \begin_inset Quotes sld
9745 \begin_inset Quotes srd
9755 \begin_inset Quotes sld
9758 from within an interrupt routine might get lost if the interrupt occurs
9761 \begin_inset Quotes sld
9766 counter\SpecialChar ~
9771 \begin_inset Quotes srd
9774 is not atomic on the 8051 even if
9778 is located in data memory.
9779 Bugs like these are hard to reproduce and can cause a lot of trouble.
9783 A special note here, int (16 bit) and long (32 bit) integer division
9784 \begin_inset LatexCommand \index{Division}
9789 \begin_inset LatexCommand \index{Multiplication}
9794 \begin_inset LatexCommand \index{Modulus}
9799 \begin_inset LatexCommand \index{Floating point support}
9803 operations are implemented using external support routines developed in
9805 If an interrupt service routine needs to do any of these operations then
9806 the support routines (as mentioned in a following section) will have to
9807 be recompiled using the
9820 \begin_inset LatexCommand \index{-\/-stack-auto}
9826 option and the source file will need to be compiled using the
9841 \begin_inset LatexCommand \index{-\/-int-long-reent}
9848 Calling other functions from an interrupt service routine is not recommended,
9849 avoid it if possible.
9850 Note that when some function is called from an interrupt service routine
9851 it should be preceded by a #pragma\SpecialChar ~
9853 \begin_inset LatexCommand \index{\#pragma nooverlay}
9857 if it is not reentrant.
9858 Furthermore nonreentrant functions should not be called from the main program
9859 while the interrupt service routine might be active.
9865 \begin_inset LatexCommand \ref{sub:Overlaying}
9870 about Overlaying and section
9871 \begin_inset LatexCommand \ref{sub:Functions-using-private-banks}
9876 about Functions using private register banks.
9879 MCS51/DS390 Interrupt Service Routines
9882 Interrupt numbers and the corresponding address & descriptions for the Standard
9883 8051/8052 are listed below.
9884 SDCC will automatically adjust the interrupt vector table to the maximum
9885 interrupt number specified.
9891 \begin_inset Tabular
9892 <lyxtabular version="3" rows="7" columns="3">
9894 <column alignment="center" valignment="top" leftline="true" width="0in">
9895 <column alignment="center" valignment="top" leftline="true" width="0in">
9896 <column alignment="center" valignment="top" leftline="true" rightline="true" width="0in">
9897 <row topline="true" bottomline="true">
9898 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
9906 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
9914 <cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
9923 <row topline="true">
9924 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
9932 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
9940 <cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
9949 <row topline="true">
9950 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
9958 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
9966 <cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
9975 <row topline="true">
9976 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
9984 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
9992 <cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
10001 <row topline="true">
10002 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
10010 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
10018 <cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
10027 <row topline="true">
10028 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
10036 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
10044 <cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
10053 <row topline="true" bottomline="true">
10054 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
10062 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
10070 <cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
10088 If the interrupt service routine is defined without
10091 \begin_inset LatexCommand \index{using (mcs51, ds390 register bank)}
10097 a register bank or with register bank 0 (
10101 0), the compiler will save the registers used by itself on the stack upon
10102 entry and restore them at exit, however if such an interrupt service routine
10103 calls another function then the entire register bank will be saved on the
10105 This scheme may be advantageous for small interrupt service routines which
10106 have low register usage.
10109 If the interrupt service routine is defined to be using a specific register
10114 & psw are saved and restored, if such an interrupt service routine calls
10115 another function (using another register bank) then the entire register
10116 bank of the called function will be saved on the stack.
10117 This scheme is recommended for larger interrupt service routines.
10120 HC08 Interrupt Service Routines
10123 Since the number of interrupts available is chip specific and the interrupt
10124 vector table always ends at the last byte of memory, the interrupt numbers
10125 corresponds to the interrupt vectors in reverse order of address.
10126 For example, interrupt 1 will use the interrupt vector at 0xfffc, interrupt
10127 2 will use the interrupt vector at 0xfffa, and so on.
10128 However, interrupt 0 (the reset vector at 0xfffe) is not redefinable in
10129 this way; instead see section
10130 \begin_inset LatexCommand \ref{sub:Startup-Code}
10134 for details on customizing startup.
10137 Enabling and Disabling Interrupts
10140 Critical Functions and Critical Statements
10143 A special keyword may be associated with a block or a function declaring
10149 SDCC will generate code to disable all interrupts
10150 \begin_inset LatexCommand \index{interrupt}
10154 upon entry to a critical function and restore the interrupt enable to the
10155 previous state before returning.
10156 Nesting critical functions will need one additional byte on the stack
10157 \begin_inset LatexCommand \index{stack}
10166 int foo () critical
10167 \begin_inset LatexCommand \index{critical}
10192 The critical attribute maybe used with other attributes like
10202 may also be used to disable interrupts more locally:
10210 More than one statement could have been included in the block.
10213 Enabling and Disabling Interrupts directly
10217 \begin_inset LatexCommand \index{interrupt}
10221 can also be disabled and enabled directly (8051):
10226 EA = 0;\SpecialChar ~
10289 EA = 1;\SpecialChar ~
10356 On other architectures which have seperate opcodes for enabling and disabling
10357 interrupts you might want to make use of defines with inline assembly
10358 \begin_inset LatexCommand \index{Assembler routines}
10368 \begin_inset LatexCommand \index{\_asm}
10377 \begin_inset LatexCommand \index{\_endasm}
10386 #define SEI _asm\SpecialChar ~
10398 Note: it is sometimes sufficient to disable only a specific interrupt source
10400 a timer or serial interrupt by manipulating an
10403 \begin_inset LatexCommand \index{interrupt mask}
10413 Usually the time during which interrupts are disabled should be kept as
10415 This minimizes both
10420 \begin_inset LatexCommand \index{interrupt latency}
10424 (the time between the occurrence of the interrupt and the execution of
10425 the first code in the interrupt routine) and
10430 \begin_inset LatexCommand \index{interrupt jitter}
10434 (the difference between the shortest and the longest interrupt latency).
10435 These really are something different, f.e.
10436 a serial interrupt has to be served before its buffer overruns so it cares
10437 for the maximum interrupt latency, whereas it does not care about jitter.
10438 On a loudspeaker driven via a digital to analog converter which is fed
10439 by an interrupt a latency of a few milliseconds might be tolerable, whereas
10440 a much smaller jitter will be very audible.
10443 You can reenable interrupts within an interrupt routine and on some architecture
10444 s you can make use of two (or more) levels of
10446 interrupt priorities
10449 \begin_inset LatexCommand \index{interrupt priority}
10454 On some architectures which don't support interrupt priorities these can
10455 be implemented by manipulating the interrupt mask and reenabling interrupts
10456 within the interrupt routine.
10457 Don't add complexity unless you have to.
10461 Functions using private register banks
10462 \begin_inset LatexCommand \label{sub:Functions-using-private-banks}
10469 Some architectures have support for quickly changing register sets.
10470 SDCC supports this feature with the
10473 \begin_inset LatexCommand \index{using (mcs51, ds390 register bank)}
10479 attribute (which tells the compiler to use a register bank
10480 \begin_inset LatexCommand \index{register bank (mcs51, ds390)}
10484 other than the default bank zero).
10485 It should only be applied to
10488 \begin_inset LatexCommand \index{interrupt}
10494 functions (see footnote below).
10495 This will in most circumstances make the generated ISR code more efficient
10496 since it will not have to save registers on the stack.
10503 attribute will have no effect on the generated code for a
10507 function (but may occasionally be useful anyway
10513 possible exception: if a function is called ONLY from 'interrupt' functions
10514 using a particular bank, it can be declared with the same 'using' attribute
10515 as the calling 'interrupt' functions.
10516 For instance, if you have several ISRs using bank one, and all of them
10517 call memcpy(), it might make sense to create a specialized version of memcpy()
10518 'using 1', since this would prevent the ISR from having to save bank zero
10519 to the stack on entry and switch to bank zero before calling the function
10526 (pending: I don't think this has been done yet)
10533 function using a non-zero bank will assume that it can trash that register
10534 bank, and will not save it.
10535 Since high-priority interrupts
10536 \begin_inset LatexCommand \index{interrupt priority}
10540 can interrupt low-priority ones on the 8051 and friends, this means that
10541 if a high-priority ISR
10545 a particular bank occurs while processing a low-priority ISR
10549 the same bank, terrible and bad things can happen.
10550 To prevent this, no single register bank should be
10554 by both a high priority and a low priority ISR.
10555 This is probably most easily done by having all high priority ISRs use
10556 one bank and all low priority ISRs use another.
10557 If you have an ISR which can change priority at runtime, you're on your
10558 own: I suggest using the default bank zero and taking the small performance
10562 It is most efficient if your ISR calls no other functions.
10563 If your ISR must call other functions, it is most efficient if those functions
10564 use the same bank as the ISR (see note 1 below); the next best is if the
10565 called functions use bank zero.
10566 It is very inefficient to call a function using a different, non-zero bank
10572 \begin_inset LatexCommand \label{sub:Startup-Code}
10577 \begin_inset LatexCommand \index{Startup code}
10584 MCS51/DS390 Startup Code
10587 The compiler inserts a call to the C routine
10589 _sdcc_external_startup()
10590 \begin_inset LatexCommand \index{\_sdcc\_external\_startup()}
10599 at the start of the CODE area.
10600 This routine is in the runtime library
10601 \begin_inset LatexCommand \index{Runtime library}
10606 By default this routine returns 0, if this routine returns a non-zero value,
10607 the static & global variable initialization will be skipped and the function
10608 main will be invoked.
10609 Otherwise static & global variables will be initialized before the function
10613 _sdcc_external_startup()
10615 routine to your program to override the default if you need to setup hardware
10616 or perform some other critical operation prior to static & global variable
10618 On some mcs51 variants xdata has to be explicitly enabled before it can
10619 be accessed, this is the place to do it.
10620 See also the compiler option
10639 \begin_inset LatexCommand \index{-\/-no-xinit-opt}
10644 \begin_inset LatexCommand \ref{sub:MCS51-variants}
10649 about MCS51-variants.
10655 The HC08 startup code follows the same scheme as the MCS51 startup code.
10661 On the Z80 the startup code is inserted by linking with crt0.o which is generated
10662 from sdcc/device/lib/z80/crt0.s.
10663 If you need a different startup code you can use the compiler option
10684 \begin_inset LatexCommand \index{-\/-no-std-crt0}
10688 and provide your own crt0.o.
10692 Inline Assembler Code
10693 \begin_inset LatexCommand \index{Assembler routines}
10700 A Step by Step Introduction
10701 \begin_inset LatexCommand \label{sub:A-Step-by Assembler Introduction}
10708 Starting from a small snippet of c-code this example shows for the MCS51
10709 how to use inline assembly, access variables, a function parameter and
10710 an array in xdata memory.
10711 The example uses an MCS51 here but is easily adapted for other architectures.
10712 This is a buffer routine which should be optimized:
10719 \begin_inset LatexCommand \index{far (storage class)}
10724 \begin_inset LatexCommand \index{at}
10729 \begin_inset LatexCommand \index{Aligned array}
10735 unsigned char head,tail;
10739 void to_buffer( unsigned char c )
10747 if( head != tail-1 )
10762 If the code snippet (assume it is saved in buffer.c) is compiled with SDCC
10763 then a corresponding buffer.asm file is generated.
10764 We define a new function
10768 in file buffer.c in which we cut and paste the generated code, removing
10769 unwanted comments and some ':'.
10771 \begin_inset Quotes sld
10775 \begin_inset Quotes srd
10779 \begin_inset Quotes sld
10783 \begin_inset Quotes srd
10786 to the beginning and the end of the function body:
10792 /* With a cut and paste from the .asm file, we have something to start with.
10797 The function is not yet OK! (registers aren't saved) */
10799 void to_buffer_asm( unsigned char c )
10808 \begin_inset LatexCommand \index{\_asm}
10822 ;buffer.c if( head != tail-1 )
10870 ;buffer.c buf[ head++ ] = c; /* access to a 256 byte aligned array */
10871 \begin_inset LatexCommand \index{Aligned array}
10940 The new file buffer.c should compile with only one warning about the unreferenced
10941 function argument 'c'.
10942 Now we hand-optimize the assembly code and insert an #define USE_ASSEMBLY
10943 (1) and finally have:
10949 unsigned char far at 0x7f00 buf[0x100];
10951 unsigned char head,tail;
10953 #define USE_ASSEMBLY (1)
10961 void to_buffer( unsigned char c )
10969 if( head != tail-1 )
10989 void to_buffer( unsigned char c )
10997 c; // to avoid warning: unreferenced function argument
11004 \begin_inset LatexCommand \index{\_asm}
11018 ; save used registers here.
11029 ; If we were still using r2,r3 we would have to push them here.
11032 ; if( head != tail-1 )
11075 ; we could do an ANL a,#0x0f here to use a smaller buffer (see below)
11099 ; buf[ head++ ] = c;
11110 a,dpl \SpecialChar ~
11117 ; dpl holds lower byte of function argument
11128 dpl,_head \SpecialChar ~
11131 ; buf is 0x100 byte aligned so head can be used directly
11173 ; we could do an ANL _head,#0x0f here to use a smaller buffer (see above)
11185 ; restore used registers here
11198 The inline assembler code can contain any valid code understood by the assembler
11199 , this includes any assembler directives and comment lines
11205 The assembler does not like some characters like ':' or ''' in comments.
11206 You'll find an 100+ pages assembler manual in sdcc/as/doc/asxhtm.html
11210 The compiler does not do any validation of the code within the
11213 \begin_inset LatexCommand \index{\_asm}
11221 Specifically it will not know which registers are used and thus register
11223 \begin_inset LatexCommand \index{push/pop}
11227 has to be done manually.
11231 It is recommended that each assembly instruction (including labels) be placed
11232 in a separate line (as the example shows).
11246 \begin_inset LatexCommand \index{-\/-peep-asm}
11252 command line option is used, the inline assembler code will be passed through
11253 the peephole optimizer
11254 \begin_inset LatexCommand \index{Peephole optimizer}
11259 There are only a few (if any) cases where this option makes sense, it might
11260 cause some unexpected changes in the inline assembler code.
11261 Please go through the peephole optimizer rules defined in file
11265 before using this option.
11269 \begin_inset LatexCommand \label{sub:Naked-Functions}
11274 \begin_inset LatexCommand \index{Naked functions}
11281 A special keyword may be associated with a function declaring it as
11284 \begin_inset LatexCommand \index{\_naked}
11295 function modifier attribute prevents the compiler from generating prologue
11296 \begin_inset LatexCommand \index{function prologue}
11301 \begin_inset LatexCommand \index{function epilogue}
11305 code for that function.
11306 This means that the user is entirely responsible for such things as saving
11307 any registers that may need to be preserved, selecting the proper register
11308 bank, generating the
11312 instruction at the end, etc.
11313 Practically, this means that the contents of the function must be written
11314 in inline assembler.
11315 This is particularly useful for interrupt functions, which can have a large
11316 (and often unnecessary) prologue/epilogue.
11317 For example, compare the code generated by these two functions:
11323 \begin_inset LatexCommand \index{volatile}
11327 data unsigned char counter;
11331 void simpleInterrupt(void) interrupt
11332 \begin_inset LatexCommand \index{interrupt}
11350 void nakedInterrupt(void) interrupt 2 _naked
11359 \begin_inset LatexCommand \index{\_asm}
11376 _counter ; does not change flags, no need to save psw
11388 ; MUST explicitly include ret or reti in _naked function.
11395 \begin_inset LatexCommand \index{\_endasm}
11404 For an 8051 target, the generated simpleInterrupt looks like:
11545 whereas nakedInterrupt looks like:
11560 _counter ; does not change flags, no need to save psw
11578 ; MUST explicitly include ret or reti in _naked function
11581 The related directive #pragma exclude
11582 \begin_inset LatexCommand \index{\#pragma exclude}
11586 allows a more fine grained control over pushing & popping
11587 \begin_inset LatexCommand \index{push/pop}
11594 While there is nothing preventing you from writing C code inside a
11598 function, there are many ways to shoot yourself in the foot doing this,
11599 and it is recommended that you stick to inline assembler.
11602 Use of Labels within Inline Assembler
11605 SDCC allows the use of in-line assembler with a few restrictions regarding
11607 In older versions of the compiler all labels defined within inline assembler
11616 where nnnn is a number less than 100 (which implies a limit of utmost 100
11617 inline assembler labels
11631 \begin_inset LatexCommand \index{\_asm}
11661 \begin_inset LatexCommand \index{\_endasm}
11668 Inline assembler code cannot reference any C-Labels, however it can reference
11670 \begin_inset LatexCommand \index{Labels}
11674 defined by the inline assembler, e.g.:
11699 ; some assembler code
11719 /* some more c code */
11721 clabel:\SpecialChar ~
11723 /* inline assembler cannot reference this label */
11735 $0003: ;label (can be referenced by inline assembler only)
11747 /* some more c code */
11752 In other words inline assembly code can access labels defined in inline
11753 assembly within the scope of the function.
11754 The same goes the other way, i.e.
11755 labels defines in inline assembly can not be accessed by C statements.
11758 Interfacing with Assembler Code
11759 \begin_inset LatexCommand \index{Assembler routines}
11766 Global Registers used for Parameter Passing
11767 \begin_inset LatexCommand \index{Parameter passing}
11774 The compiler always uses the global registers
11777 \begin_inset LatexCommand \index{DPTR, DPH, DPL}
11782 \begin_inset LatexCommand \index{DPTR}
11787 \begin_inset LatexCommand \index{B (mcs51, ds390 register)}
11796 \begin_inset LatexCommand \index{ACC (mcs51, ds390 register)}
11802 to pass the first parameter to a routine.
11803 The second parameter onwards is either allocated on the stack (for reentrant
11814 -stack-auto is used) or in data / xdata memory (depending on the memory
11819 Assembler Routine (non-reentrant)
11822 In the following example
11823 \begin_inset LatexCommand \index{reentrant}
11828 \begin_inset LatexCommand \index{Assembler routines (non-reentrant)}
11832 the function c_func calls an assembler routine asm_func, which takes two
11834 \begin_inset LatexCommand \index{function parameter}
11843 extern int asm_func(unsigned char, unsigned char);
11847 int c_func (unsigned char i, unsigned char j)
11855 return asm_func(i,j);
11869 return c_func(10,9);
11874 The corresponding assembler function is:
11879 .globl _asm_func_PARM_2
11980 \begin_inset LatexCommand \index{DPTR, DPH, DPL}
11997 Note here that the return values
11998 \begin_inset LatexCommand \index{return value}
12002 are placed in 'dpl' - One byte return value, 'dpl' LSB & 'dph' MSB for
12004 'dpl', 'dph' and 'b' for three byte values (generic pointers) and 'dpl','dph','
12005 b' & 'acc' for four byte values.
12008 The parameter naming convention is _<function_name>_PARM_<n>, where n is
12009 the parameter number starting from 1, and counting from the left.
12010 The first parameter is passed in
12011 \begin_inset Quotes eld
12015 \begin_inset Quotes erd
12018 for a one byte parameter,
12019 \begin_inset Quotes eld
12023 \begin_inset Quotes erd
12027 \begin_inset Quotes eld
12031 \begin_inset Quotes erd
12034 for three bytes and
12035 \begin_inset Quotes eld
12039 \begin_inset Quotes erd
12042 for a four bytes parameter.
12043 The variable name for the second parameter will be _<function_name>_PARM_2.
12047 Assemble the assembler routine with the following command:
12054 asx8051 -losg asmfunc.asm
12061 Then compile and link the assembler routine to the C source file with the
12069 sdcc cfunc.c asmfunc.rel
12072 Assembler Routine (reentrant)
12076 \begin_inset LatexCommand \index{reentrant}
12081 \begin_inset LatexCommand \index{Assembler routines (reentrant)}
12085 the second parameter
12086 \begin_inset LatexCommand \index{function parameter}
12090 onwards will be passed on the stack, the parameters are pushed from right
12092 after the call the leftmost parameter will be on the top of the stack.
12093 Here is an example:
12098 extern int asm_func(unsigned char, unsigned char);
12102 int c_func (unsigned char i, unsigned char j) reentrant
12110 return asm_func(i,j);
12124 return c_func(10,9);
12129 The corresponding assembler routine is:
12229 The compiling and linking procedure remains the same, however note the extra
12230 entry & exit linkage required for the assembler code, _bp is the stack
12231 frame pointer and is used to compute the offset into the stack for parameters
12232 and local variables.
12236 \begin_inset LatexCommand \index{int (16 bit)}
12241 \begin_inset LatexCommand \index{long (32 bit)}
12248 For signed & unsigned int (16 bit) and long (32 bit) variables, division,
12249 multiplication and modulus operations are implemented by support routines.
12250 These support routines are all developed in ANSI-C to facilitate porting
12251 to other MCUs, although some model specific assembler optimizations are
12253 The following files contain the described routines, all of them can be
12254 found in <installdir>/share/sdcc/lib.
12260 \begin_inset Tabular
12261 <lyxtabular version="3" rows="11" columns="2">
12263 <column alignment="center" valignment="top" leftline="true" width="0">
12264 <column alignment="center" valignment="top" leftline="true" rightline="true" width="0">
12265 <row topline="true" bottomline="true">
12266 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
12276 <cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
12287 <row topline="true">
12288 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
12296 <cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
12301 16 bit multiplication
12305 <row topline="true">
12306 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
12314 <cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
12319 signed 16 bit division (calls _divuint)
12323 <row topline="true">
12324 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
12332 <cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
12337 unsigned 16 bit division
12341 <row topline="true">
12342 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
12350 <cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
12355 signed 16 bit modulus (calls _moduint)
12359 <row topline="true">
12360 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
12368 <cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
12373 unsigned 16 bit modulus
12377 <row topline="true">
12378 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
12386 <cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
12391 32 bit multiplication
12395 <row topline="true">
12396 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
12404 <cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
12409 signed 32 division (calls _divulong)
12413 <row topline="true">
12414 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
12422 <cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
12427 unsigned 32 division
12431 <row topline="true">
12432 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
12440 <cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
12445 signed 32 bit modulus (calls _modulong)
12449 <row topline="true" bottomline="true">
12450 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
12458 <cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
12463 unsigned 32 bit modulus
12476 Since they are compiled as
12481 \begin_inset LatexCommand \index{reentrant}
12486 \begin_inset LatexCommand \index{interrupt}
12490 service routines should not do any of the above operations.
12491 If this is unavoidable then the above routines will need to be compiled
12505 \begin_inset LatexCommand \index{-\/-stack-auto}
12511 option, after which the source program will have to be compiled with
12524 \begin_inset LatexCommand \index{-\/-int-long-reent}
12531 Notice that you don't have to call these routines directly.
12532 The compiler will use them automatically every time an integer operation
12536 Floating Point Support
12537 \begin_inset LatexCommand \index{Floating point support}
12544 SDCC supports IEEE (single precision 4 bytes) floating point numbers.The
12545 floating point support routines are derived from gcc's floatlib.c and consist
12546 of the following routines:
12554 \begin_inset Tabular
12555 <lyxtabular version="3" rows="17" columns="2">
12557 <column alignment="center" valignment="top" leftline="true" width="0">
12558 <column alignment="center" valignment="top" leftline="true" rightline="true" width="0">
12559 <row topline="true" bottomline="true">
12560 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
12577 <cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
12586 <row topline="true">
12587 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
12604 <cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
12618 add floating point numbers
12622 <row topline="true">
12623 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
12640 <cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
12654 subtract floating point numbers
12658 <row topline="true">
12659 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
12676 <cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
12690 divide floating point numbers
12694 <row topline="true">
12695 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
12712 <cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
12726 multiply floating point numbers
12730 <row topline="true">
12731 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
12748 <cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
12762 convert floating point to unsigned char
12766 <row topline="true">
12767 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
12784 <cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
12798 convert floating point to signed char
12802 <row topline="true">
12803 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
12820 <cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
12834 convert floating point to unsigned int
12838 <row topline="true">
12839 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
12856 <cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
12870 convert floating point to signed int
12874 <row topline="true">
12875 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
12901 <cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
12915 convert floating point to unsigned long
12919 <row topline="true">
12920 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
12937 <cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
12951 convert floating point to signed long
12955 <row topline="true">
12956 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
12973 <cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
12987 convert unsigned char to floating point
12991 <row topline="true">
12992 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
13009 <cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
13023 convert char to floating point number
13027 <row topline="true">
13028 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
13045 <cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
13059 convert unsigned int to floating point
13063 <row topline="true">
13064 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
13081 <cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
13095 convert int to floating point numbers
13099 <row topline="true">
13100 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
13117 <cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
13131 convert unsigned long to floating point number
13135 <row topline="true" bottomline="true">
13136 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
13153 <cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
13167 convert long to floating point number
13180 These support routines are developed in ANSI-C so there is room for space
13181 and speed improvement.
13182 Note if all these routines are used simultaneously the data space might
13184 For serious floating point usage it is recommended that the large model
13186 Also notice that you don't have to call this routines directly.
13187 The compiler will use them automatically every time a floating point operation
13192 \begin_inset LatexCommand \index{Libraries}
13201 <pending: this is messy and incomplete - a little more information is in
13202 sdcc/doc/libdoc.txt
13207 Compiler support routines (_gptrget, _mulint etc.)
13210 Stdclib functions (puts, printf, strcat etc.)
13211 \layout Subsubsection
13217 \begin_inset LatexCommand \index{<stdio.h>}
13221 As usual on embedded systems you have to provide your own
13224 \begin_inset LatexCommand \index{getchar()}
13233 \begin_inset LatexCommand \index{putchar()}
13240 SDCC does not know whether the system connects to a serial line with or
13241 without handshake, LCD, keyboard or other device.
13242 You'll find examples for serial routines f.e.
13243 in sdcc/device/lib.
13246 If you're short on memory you might want to use
13257 \begin_inset LatexCommand \index{printf()}
13264 For the mcs51 there is an assembly version
13268 which should fit the requirements of many embedded systems (by unsetting
13269 #defines it can be customized to
13273 support long variables and field widths).
13276 Math functions (sin, pow, sqrt etc.)
13283 \begin_inset LatexCommand \index{Libraries}
13287 included in SDCC should have a license at least as liberal as the GNU Lesser
13288 General Public License
13289 \begin_inset LatexCommand \index{GNU Lesser General Public License, LGPL}
13300 license statements for the libraries are missing.
13301 sdcc/device/lib/ser_ir.c
13305 come with a GPL (as opposed to LGPL) License - this will not be liberal
13306 enough for many embedded programmers.
13309 If you have ported some library or want to share experience about some code
13311 falls into any of these categories Busses (I
13312 \begin_inset Formula $^{\textrm{2}}$
13315 C, CAN, Ethernet, Profibus, Modbus, USB, SPI, JTAG ...), Media (IDE, Memory
13316 cards, eeprom, flash...), En-/Decryption, Remote debugging, Realtime kernel,
13317 Keyboard, LCD, RTC, FPGA, PID then the sdcc-user mailing list
13318 \begin_inset LatexCommand \url{http://sourceforge.net/mail/?group_id=599}
13323 would certainly like to hear about it.
13324 Programmers coding for embedded systems are not especially famous for being
13325 enthusiastic, so don't expect a big hurray but as the mailing list is searchabl
13326 e these references are very valuable.
13327 Let's help to create a climate where information is shared.
13333 MCS51 Memory Models
13334 \begin_inset LatexCommand \index{Memory model}
13339 \begin_inset LatexCommand \index{MCS51 memory model}
13344 \layout Subsubsection
13349 SDCC allows two memory models for MCS51 code,
13358 Modules compiled with different memory models should
13362 be combined together or the results would be unpredictable.
13363 The library routines supplied with the compiler are compiled as both small
13365 The compiled library modules are contained in separate directories as small
13366 and large so that you can link to either set.
13370 When the large model is used all variables declared without a storage class
13371 will be allocated into the external ram, this includes all parameters and
13372 local variables (for non-reentrant
13373 \begin_inset LatexCommand \index{reentrant}
13378 When the small model is used variables without storage class are allocated
13379 in the internal ram.
13382 Judicious usage of the processor specific storage classes
13383 \begin_inset LatexCommand \index{Storage class}
13387 and the 'reentrant' function type will yield much more efficient code,
13388 than using the large model.
13389 Several optimizations are disabled when the program is compiled using the
13390 large model, it is therefore recommended that the small model be used unless
13391 absolutely required.
13392 \layout Subsubsection
13395 \begin_inset LatexCommand \label{sub:External-Stack}
13400 \begin_inset LatexCommand \index{stack}
13405 \begin_inset LatexCommand \index{External stack (mcs51)}
13416 : this option wasn't maintained for a long time and is quite buggy.
13417 Small programs might work.
13418 You've been warned!
13421 The external stack (-
13432 \begin_inset LatexCommand \index{-\/-xstack}
13436 ) is located in pdata
13437 \begin_inset LatexCommand \index{pdata (mcs51, ds390 storage class)}
13441 memory (usually at the start of the external ram segment) and is 256 bytes
13453 -xstack option is used to compile the program, the parameters and local
13455 \begin_inset LatexCommand \index{local variables}
13459 of all reentrant functions are allocated in this area.
13460 This option is provided for programs with large stack space requirements.
13461 When used with the -
13472 \begin_inset LatexCommand \index{-\/-stack-auto}
13476 option, all parameters and local variables are allocated on the external
13477 stack (note: support libraries will need to be recompiled with the same
13481 The compiler outputs the higher order address byte of the external ram segment
13483 \begin_inset LatexCommand \index{P2 (mcs51 sfr)}
13488 \begin_inset LatexCommand \ref{sub:MCS51-variants}
13492 ), therefore when using the External Stack option, this port
13496 be used by the application program.
13500 \begin_inset LatexCommand \index{Memory model}
13505 \begin_inset LatexCommand \index{DS390 memory model}
13512 The only model supported is Flat 24
13513 \begin_inset LatexCommand \index{Flat 24 (DS390 memory model)}
13518 This generates code for the 24 bit contiguous addressing mode of the Dallas
13520 In this mode, up to four meg of external RAM or code space can be directly
13522 See the data sheets at www.dalsemi.com for further information on this part.
13526 Note that the compiler does not generate any code to place the processor
13527 into 24 bitmode (although
13531 in the ds390 libraries will do that for you).
13537 \begin_inset LatexCommand \index{Tinibios (DS390)}
13541 , the boot loader or similar code must ensure that the processor is in 24
13542 bit contiguous addressing mode before calling the SDCC startup code.
13560 option, variables will by default be placed into the XDATA segment.
13565 Segments may be placed anywhere in the 4 meg address space using the usual
13577 Note that if any segments are located above 64K, the -r flag must be passed
13578 to the linker to generate the proper segment relocations, and the Intel
13579 HEX output format must be used.
13580 The -r flag can be passed to the linker by using the option
13584 on the SDCC command line.
13585 However, currently the linker can not handle code segments > 64k.
13589 \begin_inset LatexCommand \index{Pragmas}
13596 SDCC supports the following #pragma directives:
13600 \begin_inset LatexCommand \index{\#pragma save}
13604 - this will save all current options to the save/restore stack.
13609 \begin_inset LatexCommand \index{\#pragma restore}
13613 - will restore saved options from the last save.
13614 saves & restores can be nested.
13615 SDCC uses a save/restore stack: save pushes current options to the stack,
13616 restore pulls current options from the stack.
13621 \begin_inset LatexCommand \index{\#pragma nogcse}
13625 - will stop global common subexpression elimination.
13629 \begin_inset LatexCommand \index{\#pragma noinduction}
13633 - will stop loop induction optimizations.
13637 \begin_inset LatexCommand \index{\#pragma nojtbound}
13641 - will not generate code for boundary value checking, when switch statements
13642 are turned into jump-tables (dangerous).
13643 For more details see section
13644 \begin_inset LatexCommand \ref{sub:'switch'-Statements}
13652 \begin_inset LatexCommand \index{\#pragma nooverlay}
13656 - the compiler will not overlay the parameters and local variables of a
13661 \begin_inset LatexCommand \index{\#pragma less\_pedantic}
13665 - the compiler will not warn you anymore for obvious mistakes, you'r on
13670 \begin_inset LatexCommand \index{\#pragma noloopreverse}
13674 - Will not do loop reversal optimization
13678 \begin_inset LatexCommand \index{\#pragma exclude}
13682 none | {acc[,b[,dpl[,dph]]] - The exclude pragma disables generation of
13684 \begin_inset LatexCommand \index{push/pop}
13688 instruction in ISR function (using interrupt
13689 \begin_inset LatexCommand \index{interrupt}
13694 The directive should be placed immediately before the ISR function definition
13695 and it affects ALL ISR functions following it.
13696 To enable the normal register saving for ISR functions use #pragma\SpecialChar ~
13697 exclude\SpecialChar ~
13699 \begin_inset LatexCommand \index{\#pragma exclude}
13707 \begin_inset LatexCommand \index{\#pragma noiv}
13711 - Do not generate interrupt
13712 \begin_inset LatexCommand \index{interrupt}
13716 vector table entries for all ISR functions defined after the pragma.
13717 This is useful in cases where the interrupt vector table must be defined
13718 manually, or when there is a secondary, manually defined interrupt vector
13720 for the autovector feature of the Cypress EZ-USB FX2).
13721 More elegantly this can be achieved by obmitting the optional interrupt
13722 number after the interrupt keyword, see section
13723 \begin_inset LatexCommand \ref{sub:Interrupt-Service-Routines}
13732 \begin_inset LatexCommand \index{\#pragma callee\_saves}
13737 \begin_inset LatexCommand \index{function prologue}
13741 function1[,function2[,function3...]] - The compiler by default uses a caller
13742 saves convention for register saving across function calls, however this
13743 can cause unnecessary register pushing & popping
13744 \begin_inset LatexCommand \index{push/pop}
13748 when calling small functions from larger functions.
13749 This option can be used to switch off the register saving convention for
13750 the function names specified.
13751 The compiler will not save registers when calling these functions, extra
13752 code need to be manually inserted at the entry & exit for these functions
13753 to save & restore the registers used by these functions, this can SUBSTANTIALLY
13754 reduce code & improve run time performance of the generated code.
13755 In the future the compiler (with inter procedural analysis) may be able
13756 to determine the appropriate scheme to use for each function call.
13767 -callee-saves command line option is used, the function names specified
13768 in #pragma\SpecialChar ~
13770 \begin_inset LatexCommand \index{\#pragma callee\_saves}
13774 is appended to the list of functions specified in the command line.
13777 SDCPP supports the following #pragma directives:
13781 \begin_inset LatexCommand \index{\#pragma preproc\_asm}
13785 (+ | -) - switch _asm _endasm block preprocessing on / off.
13789 The pragma's are intended to be used to turn-on or off certain optimizations
13790 which might cause the compiler to generate extra stack / data space to
13791 store compiler generated temporary variables.
13792 This usually happens in large functions.
13793 Pragma directives should be used as shown in the following example, they
13794 are used to control options & optimizations for a given function; pragmas
13795 should be placed before and/or after a function, placing pragma's inside
13796 a function body could have unpredictable results.
13802 \begin_inset LatexCommand \index{\#pragma save}
13813 /* save the current settings */
13816 \begin_inset LatexCommand \index{\#pragma nogcse}
13825 /* turnoff global subexpression elimination */
13827 #pragma noinduction
13828 \begin_inset LatexCommand \index{\#pragma noinduction}
13832 /* turn off induction optimizations */
13855 \begin_inset LatexCommand \index{\#pragma restore}
13859 /* turn the optimizations back on */
13862 The compiler will generate a warning message when extra space is allocated.
13863 It is strongly recommended that the save and restore pragma's be used when
13864 changing options for a function.
13867 Defines Created by the Compiler
13870 The compiler creates the following #defines
13871 \begin_inset LatexCommand \index{\#defines}
13876 \begin_inset LatexCommand \index{Defines created by the compiler}
13886 \begin_inset Tabular
13887 <lyxtabular version="3" rows="10" columns="2">
13889 <column alignment="center" valignment="top" leftline="true" width="0">
13890 <column alignment="center" valignment="top" leftline="true" rightline="true" width="0">
13891 <row topline="true" bottomline="true">
13892 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
13902 <cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
13913 <row topline="true">
13914 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
13920 \begin_inset LatexCommand \index{SDCC}
13927 <cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
13932 this Symbol is always defined
13936 <row topline="true">
13937 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
13943 \begin_inset LatexCommand \index{SDCC\_mcs51}
13948 \begin_inset LatexCommand \index{SDCC\_ds390}
13953 \begin_inset LatexCommand \index{SDCC\_z80}
13960 <cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
13965 depending on the model used (e.g.: -mds390
13969 <row topline="true">
13970 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
13976 \begin_inset LatexCommand \index{\_\_mcs51}
13981 \begin_inset LatexCommand \index{\_\_ds390}
13986 \begin_inset LatexCommand \index{\_\_hc08}
13991 \begin_inset LatexCommand \index{\_\_z80}
13998 <cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
14003 depending on the model used (e.g.
14008 <row topline="true">
14009 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
14015 \begin_inset LatexCommand \index{SDCC\_STACK\_AUTO}
14022 <cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
14045 <row topline="true">
14046 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
14052 \begin_inset LatexCommand \index{SDCC\_MODEL\_SMALL}
14059 <cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
14082 <row topline="true">
14083 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
14089 \begin_inset LatexCommand \index{SDCC\_MODEL\_LARGE}
14096 <cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
14119 <row topline="true">
14120 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
14126 \begin_inset LatexCommand \index{SDCC\_USE\_XSTACK}
14133 <cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
14156 <row topline="true">
14157 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
14163 \begin_inset LatexCommand \index{SDCC\_STACK\_TENBIT}
14170 <cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
14183 <row topline="true" bottomline="true">
14184 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
14190 \begin_inset LatexCommand \index{SDCC\_MODEL\_FLAT24}
14197 <cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
14217 Notes on supported Processors
14221 \begin_inset LatexCommand \label{sub:MCS51-variants}
14226 \begin_inset LatexCommand \index{MCS51 variants}
14233 MCS51 processors are available from many vendors and come in many different
14235 While they might differ considerably in respect to Special Function Registers
14236 the core MCS51 is usually not modified or is kept compatible.
14240 pdata access by SFR
14243 With the upcome of devices with internal xdata and flash memory devices
14245 \begin_inset LatexCommand \index{P2 (mcs51 sfr)}
14249 as dedicated I/O port is becoming more popular.
14250 Switching the high byte for pdata
14251 \begin_inset LatexCommand \index{pdata (mcs51, ds390 storage class)}
14255 access which was formerly done by port P2 is then achieved by a Special
14257 \begin_inset LatexCommand \index{sfr}
14262 In well-established MCS51 tradition the address of this
14266 is where the chip designers decided to put it.
14267 Needless to say that they didn't agree on a common name either.
14268 As pdata addressing is used in the startup code for the initialization
14269 of xdata variables a separate startup code should be used as described
14271 \begin_inset LatexCommand \ref{sub:Startup-Code}
14278 Other Features available by SFR
14281 Some MCS51 variants offer features like Double DPTR
14282 \begin_inset LatexCommand \index{DPTR}
14286 , multiple DPTR, decrementing DPTR, 16x16 Multiply.
14287 These are currently not used for the MCS51 port.
14288 If you absolutely need them you can fall back to inline assembly or submit
14292 The Z80 and gbz80 port
14295 SDCC can target both the Zilog
14296 \begin_inset LatexCommand \index{Z80}
14300 and the Nintendo Gameboy's Z80-like gbz80
14301 \begin_inset LatexCommand \index{gbz80 (GameBoy Z80)}
14306 The Z80 port is passed through the same
14309 \begin_inset LatexCommand \index{Regression test}
14315 as the MCS51 and DS390 ports, so floating point support, support for long
14316 variables and bitfield support is fine.
14317 See mailing lists and forums about interrupt routines.
14320 As always, the code is the authoritative reference - see z80/ralloc.c and
14323 \begin_inset LatexCommand \index{stack}
14327 frame is similar to that generated by the IAR Z80 compiler.
14328 IX is used as the base pointer, HL and IY are used as a temporary registers,
14329 and BC and DE are available for holding variables.
14331 \begin_inset LatexCommand \index{return value}
14335 for the Z80 port are stored in L (one byte), HL (two bytes), or DEHL (four
14337 The gbz80 port use the same set of registers for the return values, but
14338 in a different order of significance: E (one byte), DE (two bytes), or
14345 The port to the Motorola HC08
14346 \begin_inset LatexCommand \index{HC08}
14350 family has been added in October 2003, and is still undergoing some basic
14352 The code generator is complete, but the register allocation is still quite
14354 Some of the SDCC's standard C library functions have embedded non-HC08
14355 inline assembly and so are not yet usable.
14366 \begin_inset LatexCommand \index{PIC14}
14370 port still requires a major effort from the development community.
14371 However it can work for very simple code.
14374 C code and 14bit PIC code page
14375 \begin_inset LatexCommand \index{code page (pic14)}
14380 \begin_inset LatexCommand \index{RAM bank (pic14)}
14387 The linker organizes allocation for the code page and RAM banks.
14388 It does not have intimate knowledge of the code flow.
14389 It will put all the code section of a single asm file into a single code
14391 In order to make use of multiple code pages, separate asm files must be
14393 The compiler treats all functions of a single C file as being in the same
14394 code page unless it is non static.
14395 The compiler treats all local variables of a single C file as being in
14396 the same RAM bank unless it is an extern.
14400 To get the best follow these guide lines:
14403 make local functions static, as non static functions require code page selection
14407 Make local variables static as extern variables require RAM bank selection
14411 For devices that have multiple code pages it is more efficient to use the
14412 same number of files as pages, i.e.
14413 for the 16F877 use 4 separate files and i.e.
14414 for the 16F874 use 2 separate files.
14415 This way the linker can put the code for each file into different code
14416 pages and the compiler can allocate reusable variables more efficiently
14417 and there's less page selection overhead.
14418 And as for any 8 bit micro (especially for PIC 14 as they have a very simple
14419 instruction set) use 'unsigned char' whereever possible instead of 'int'.
14422 Creating a device include file
14425 For generating a device include file use the support perl script inc2h.pl
14426 kept in directory support/script.
14432 For the interrupt function, use the keyword 'interrupt'
14433 \begin_inset LatexCommand \index{interrupt}
14437 with level number of 0 (PIC14 only has 1 interrupt so this number is only
14438 there to avoid a syntax error - it ought to be fixed).
14444 void Intr(void) interrupt 0
14450 T0IF = 0; /* Clear timer interrupt */
14455 Linking and assembling
14457 For assembling you can use either GPUTILS'
14458 \begin_inset LatexCommand \index{gputils (pic tools)}
14462 gpasm.exe or MPLAB's mpasmwin.exe.
14463 For linking you can use either GPUTIL's gplink or MPLAB's mplink.exe.
14464 If you use MPLAB and an interrupt function then the linker script file
14465 vectors section will need to be enlarged to link with mplink.
14488 sdcc -S -V -mpic14 -p16F877 $<
14502 $(PRJ).hex: $(OBJS)
14512 gplink -m -s $(PRJ).lkr -o $(PRJ).hex $(OBJS)
14534 sdcc -S -V -mpic14 -p16F877 $<
14544 mpasmwin /q /o $*.asm
14548 $(PRJ).hex: $(OBJS)
14558 mplink /v $(PRJ).lkr /m $(PRJ).map /o $(PRJ).hex $(OBJS)
14562 \begin_inset LatexCommand \index{PIC16}
14570 \begin_inset LatexCommand \index{PIC16}
14574 port is the portion of SDCC that is responsible to produce code for the
14576 \begin_inset LatexCommand \index{Microchip}
14580 (TM) microcontrollers with 16 bit core.
14581 Currently this family of microcontrollers contains the PIC18Fxxx and PIC18Fxxxx.
14587 PIC16 port supports the standard command line arguments as supposed, with
14588 the exception of certain cases that will be mentioned in the following
14591 \labelwidthstring 00.00.0000
14603 -stack-auto Auto variables that are function parameters, will be saved on
14607 There is no need to specify this in the command line.
14609 \labelwidthstring 00.00.0000
14621 -float-reent All floating point functions are reentrant by default.
14624 There is no need to specifiy this in the command line.
14626 \labelwidthstring 00.00.0000
14638 -callee-saves See -
14650 \labelwidthstring 00.00.0000
14662 -all-callee-saves All function arguments are passed on stack by default.
14665 There is no need to specify this in the command line.
14667 \labelwidthstring 00.00.0000
14679 -fommit-frame-pointer Frame pointer will be omitted when the function uses
14680 no local variables.
14683 Port Specific Options
14686 The port specific options appear after the global options in the sdcc --help
14688 \layout Subsubsection
14693 General options enable certain port features and optimizations.
14695 \labelwidthstring 00.00.0000
14707 -pgen-bank Instructs the port to insert BANKSEL directives before instructions
14708 that use the Bank Select Register (BSR).
14710 \labelwidthstring 00.00.0000
14722 -pomit-config-words Instructs the port to omit the generation of the configurati
14725 \labelwidthstring 00.00.0000
14737 -pomit-ivt Instructs the port to omit the generation of the interrupt vectors
14739 \labelwidthstring 00.00.0000
14751 -pleave-reset-vector Used in conjuction with the previous command, instructs
14752 the port NOT to omit the reset vector.
14754 \labelwidthstring 00.00.0000
14766 -stack-model=[model] Used in conjuction with the command above.
14767 Defines the stack model to be used, valid stack models are :
14770 \labelwidthstring 00.00.0000
14776 Selects small stack model.
14777 8 bit stack and frame pointers.
14778 Supports 256 bytes stack size.
14780 \labelwidthstring 00.00.0000
14786 Selects large stack model.
14787 16 bit stack and frame pointers.
14788 Supports 65536 bytes stack size.
14791 \labelwidthstring 00.00.0000
14803 -preplace-udata-with=[kword] Replaces the default udata keyword for allocating
14804 unitialized data variables with [kword].
14805 Valid keywords are: "udata_acs", "udata_shr", "udata_ovr".
14806 \layout Subsubsection
14811 Debugging options enable extra debugging information in the output files.
14813 \labelwidthstring 00.00.0000
14825 -debug-xtra Similar to --debug, but dumps more information.
14827 \labelwidthstring 00.00.0000
14839 -debug-ralloc Force register allocator to dump <source>.d file with debugging
14841 <source> is the name of the file compiled.
14843 \labelwidthstring 00.00.0000
14855 -pcode-verbose Enable pcode debugging information in translation.
14858 Preprocessor Macros
14861 PIC16 port defines the following preprocessor macros while translating a
14866 \begin_inset Tabular
14867 <lyxtabular version="3" rows="2" columns="2">
14869 <column alignment="center" valignment="top" leftline="true" width="0">
14870 <column alignment="center" valignment="top" leftline="true" rightline="true" width="0">
14871 <row topline="true" bottomline="true">
14872 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
14880 <cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
14889 <row topline="true" bottomline="true">
14890 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
14898 <cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
14903 MCU Identification.
14908 is the microcontrol identification number, i.e.
14923 PIC16 port uses the following directories for searching header files and
14928 \begin_inset Tabular
14929 <lyxtabular version="3" rows="3" columns="4">
14931 <column alignment="center" valignment="top" leftline="true" width="0">
14932 <column alignment="center" valignment="top" leftline="true" rightline="true" width="0">
14933 <column alignment="center" valignment="top" width="0">
14934 <column alignment="center" valignment="top" leftline="true" rightline="true" width="0">
14935 <row topline="true" bottomline="true">
14936 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
14944 <cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
14952 <cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
14960 <cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
14969 <row topline="true">
14970 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
14975 PREFIX/sdcc/include/pic16
14978 <cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
14983 PIC16 specific headers
14986 <cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
14994 <cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
15003 <row topline="true" bottomline="true">
15004 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
15009 PREFIX/sdcc/lib/pic16
15012 <cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
15017 PIC16 specific libraries
15020 <cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
15028 <cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
15047 PIC16 port currently supports the following pragmas:
15049 \labelwidthstring 00.00.0000
15051 stack pragma stack forces the code generator to initialize the stack & frame
15052 pointers at a specific address.
15053 This is an adhoc solution since gplink does not support yet stack.
15054 When the gplink issue is resolved the pragma will be deprecated
15062 It is important to initialize the stack, otherwise strange things can happen.
15063 Stack is not initialized by default because there are some sources that
15065 (like library sources)
15070 The stack pragma should be used only once in a project.
15071 Multiple pragmas may result in indeterminate behaviour of the program.
15073 If you omit setting the pragma the port emits a warning message before linking.
15074 If not initializing the stack is desired ignore the message.
15082 /* initializes stack at RAM address 0x5ff*/
15085 #pragma stack 0x5ff
15093 There is one main header file that can be included to the source files using
15100 This header file contains the definitions for the processor special registers,
15101 so it is necessery if the soruce accesses them.
15102 It can be included by adding the following line in the beginning of the
15106 #include <pic18fregs.h>
15109 The specific microcontroller is selected within the pic18fregs.h automatically,
15110 so the same source can be used with a variety of devices.
15116 The libraries that pic16 port depends on are the microcontroller device
15117 libraries which contain the symbol definitions for the microcontroller
15118 special function registers.
15119 These libraries have the format pic18fxxxx.lib, where
15123 is the microcontroller identification number.
15124 The specific library is selected automatically by the compiler at link
15125 stage according to the selected device.
15128 Libraries are created with gplib which is part of the gputils package
15129 \begin_inset LatexCommand \url{http://gputils.sourceforge.net}
15139 The following memory models are supported by PIC16 port:
15148 Memory model affects the default size of pointers within the source.
15149 The sizes are shown in the next table:
15153 \begin_inset Tabular
15154 <lyxtabular version="3" rows="3" columns="3">
15156 <column alignment="center" valignment="top" leftline="true" rightline="true" width="0">
15157 <column alignment="center" valignment="top" leftline="true" width="0">
15158 <column alignment="center" valignment="top" leftline="true" rightline="true" width="0">
15159 <row topline="true" bottomline="true">
15160 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
15165 Pointer sizes according to memory model
15168 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
15176 <cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
15185 <row topline="true" bottomline="true">
15186 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
15194 <cell multicolumn="1" alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
15202 <cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
15211 <row topline="true" bottomline="true">
15212 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
15220 <cell multicolumn="1" alignment="center" valignment="top" topline="true" bottomline="true" leftline="true" usebox="none">
15228 <cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
15244 It is advisable that all sources within a project are compiled with the
15246 If one wants to override the default memory model, this can be done by
15247 declaring a pointer as
15256 Far selects large memory model's pointers, while near selects small memory
15260 The standard device libraries (see 4.5.6) contain no reference to pointers,
15261 so they can be used with both memory models.
15267 The stack implementation for the PIC16 port uses two indirect registers,
15270 \labelwidthstring 00.00.0000
15272 FSR1 is assigned as stack pointer
15274 \labelwidthstring 00.00.0000
15276 FSR2 is assigned as frame pointer
15279 The following stack models are supported by PIC16 port
15292 model means that only the FSRxL byte is used to access stack and frame,
15299 uses both FSRxL and FSRxH registers.
15300 The following table shows the stack/frame pointers sizes according to stack
15301 model and the maximum space they can address:
15305 \begin_inset Tabular
15306 <lyxtabular version="3" rows="3" columns="3">
15308 <column alignment="center" valignment="top" leftline="true" rightline="true" width="0">
15309 <column alignment="center" valignment="top" leftline="true" width="0">
15310 <column alignment="center" valignment="top" leftline="true" rightline="true" width="0">
15311 <row topline="true" bottomline="true">
15312 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
15317 Stack & Frame pointer sizes according to stack model
15320 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
15328 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
15337 <row topline="true">
15338 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
15346 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
15354 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
15363 <row topline="true" bottomline="true">
15364 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
15372 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
15380 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
15398 Currently stack and frame pointers should be initialized explicit by the
15399 user at the desired Data RAM position (see 4.5.5 Pragma Stack).
15400 Uninitialized stack and frame pointers can result in unexpected behavior
15401 of the resulting binary.
15404 Function return values
15407 Return values from functions are placed to the appropriate registers following
15408 a modified Microchip policy optimized for SDCC.
15409 The following table shows these registers:
15413 \begin_inset Tabular
15414 <lyxtabular version="3" rows="6" columns="2">
15416 <column alignment="center" valignment="top" leftline="true" width="0">
15417 <column alignment="center" valignment="top" leftline="true" rightline="true" width="0">
15418 <row topline="true" bottomline="true">
15419 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
15427 <cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
15432 destination register
15436 <row topline="true">
15437 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
15445 <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">
15463 <cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
15472 <row topline="true">
15473 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
15481 <cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
15490 <row topline="true">
15491 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
15499 <cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
15504 FSR0L:PRODH:PRODL:WREG
15508 <row topline="true" bottomline="true">
15509 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
15517 <cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
15522 on stack, FSR0 points to the beginning
15536 When entering an interrupt, currently the PIC16 port automatically saves
15537 the following registers:
15549 PROD (PRODL and PRODH)
15552 FSR0 (FSR0L and FSR0H)
15555 These registers are restored upon return from the interrupt routine
15561 NOTE that when the _naked attribute is specified for an interrupt routine,
15562 then NO registers are stored or restored.
15568 Debugging with SDCDB
15569 \begin_inset LatexCommand \label{cha:Debugging-with-SDCDB}
15574 \begin_inset LatexCommand \index{sdcdb (debugger)}
15581 SDCC is distributed with a source level debugger
15582 \begin_inset LatexCommand \index{Debugger}
15587 The debugger uses a command line interface, the command repertoire of the
15588 debugger has been kept as close to gdb
15589 \begin_inset LatexCommand \index{gdb}
15593 (the GNU debugger) as possible.
15594 The configuration and build process is part of the standard compiler installati
15595 on, which also builds and installs the debugger in the target directory
15596 specified during configuration.
15597 The debugger allows you debug BOTH at the C source and at the ASM source
15599 Sdcdb is available on Unix platforms only.
15602 Compiling for Debugging
15605 The \SpecialChar \-
15607 debug option must be specified for all files for which debug information
15608 is to be generated.
15609 The complier generates a .adb file for each of these files.
15610 The linker creates the .cdb
15611 \begin_inset LatexCommand \index{<file>.cdb}
15616 \begin_inset LatexCommand \index{<file>.adb}
15620 files and the address information.
15621 This .cdb is used by the debugger.
15624 How the Debugger Works
15637 -debug option is specified the compiler generates extra symbol information
15638 some of which are put into the assembler source and some are put into the
15640 Then the linker creates the .cdb file from the individual .adb files with
15641 the address information for the symbols.
15642 The debugger reads the symbolic information generated by the compiler &
15643 the address information generated by the linker.
15644 It uses the SIMULATOR (Daniel's S51) to execute the program, the program
15645 execution is controlled by the debugger.
15646 When a command is issued for the debugger, it translates it into appropriate
15647 commands for the simulator.
15650 Starting the Debugger
15653 The debugger can be started using the following command line.
15654 (Assume the file you are debugging has the file name foo).
15668 The debugger will look for the following files.
15671 foo.c - the source file.
15674 foo.cdb - the debugger symbol information file.
15677 foo.ihx - the Intel hex format
15678 \begin_inset LatexCommand \index{Intel hex format}
15685 Command Line Options.
15698 -directory=<source file directory> this option can used to specify the directory
15700 The debugger will look into the directory list specified for source, cdb
15702 The items in the directory list must be separated by ':', e.g.
15703 if the source files can be in the directories /home/src1 and /home/src2,
15714 -directory option should be -
15724 -directory=/home/src1:/home/src2.
15725 Note there can be no spaces in the option.
15729 -cd <directory> - change to the <directory>.
15732 -fullname - used by GUI front ends.
15735 -cpu <cpu-type> - this argument is passed to the simulator please see the
15736 simulator docs for details.
15739 -X <Clock frequency > this options is passed to the simulator please see
15740 the simulator docs for details.
15743 -s <serial port file> passed to simulator see the simulator docs for details.
15746 -S <serial in,out> passed to simulator see the simulator docs for details.
15749 -k <port number> passed to simulator see the simulator docs for details.
15755 As mentioned earlier the command interface for the debugger has been deliberatel
15756 y kept as close the GNU debugger gdb, as possible.
15757 This will help the integration with existing graphical user interfaces
15758 (like ddd, xxgdb or xemacs) existing for the GNU debugger.
15759 If you use a graphical user interface for the debugger you can skip the
15761 \layout Subsubsection*
15763 break [line | file:line | function | file:function]
15766 Set breakpoint at specified line or function:
15775 sdcdb>break foo.c:100
15777 sdcdb>break funcfoo
15779 sdcdb>break foo.c:funcfoo
15780 \layout Subsubsection*
15782 clear [line | file:line | function | file:function ]
15785 Clear breakpoint at specified line or function:
15794 sdcdb>clear foo.c:100
15796 sdcdb>clear funcfoo
15798 sdcdb>clear foo.c:funcfoo
15799 \layout Subsubsection*
15804 Continue program being debugged, after breakpoint.
15805 \layout Subsubsection*
15810 Execute till the end of the current function.
15811 \layout Subsubsection*
15816 Delete breakpoint number 'n'.
15817 If used without any option clear ALL user defined break points.
15818 \layout Subsubsection*
15820 info [break | stack | frame | registers ]
15823 info break - list all breakpoints
15826 info stack - show the function call stack.
15829 info frame - show information about the current execution frame.
15832 info registers - show content of all registers.
15833 \layout Subsubsection*
15838 Step program until it reaches a different source line.
15839 Note: pressing <return> repeats the last command.
15840 \layout Subsubsection*
15845 Step program, proceeding through subroutine calls.
15846 \layout Subsubsection*
15851 Start debugged program.
15852 \layout Subsubsection*
15857 Print type information of the variable.
15858 \layout Subsubsection*
15863 print value of variable.
15864 \layout Subsubsection*
15869 load the given file name.
15870 Note this is an alternate method of loading file for debugging.
15871 \layout Subsubsection*
15876 print information about current frame.
15877 \layout Subsubsection*
15882 Toggle between C source & assembly source.
15883 \layout Subsubsection*
15885 ! simulator command
15888 Send the string following '!' to the simulator, the simulator response is
15890 Note the debugger does not interpret the command being sent to the simulator,
15891 so if a command like 'go' is sent the debugger can loose its execution
15892 context and may display incorrect values.
15893 \layout Subsubsection*
15900 My name is Bobby Brown"
15903 Interfacing with XEmacs
15904 \begin_inset LatexCommand \index{XEmacs}
15909 \begin_inset LatexCommand \index{Emacs}
15916 Two files (in emacs lisp) are provided for the interfacing with XEmacs,
15917 sdcdb.el and sdcdbsrc.el.
15918 These two files can be found in the $(prefix)/bin directory after the installat
15920 These files need to be loaded into XEmacs for the interface to work.
15921 This can be done at XEmacs startup time by inserting the following into
15922 your '.xemacs' file (which can be found in your HOME directory):
15928 (load-file sdcdbsrc.el)
15934 .xemacs is a lisp file so the () around the command is REQUIRED.
15935 The files can also be loaded dynamically while XEmacs is running, set the
15936 environment variable 'EMACSLOADPATH' to the installation bin directory
15937 (<installdir>/bin), then enter the following command ESC-x load-file sdcdbsrc.
15938 To start the interface enter the following command:
15952 You will prompted to enter the file name to be debugged.
15957 The command line options that are passed to the simulator directly are bound
15958 to default values in the file sdcdbsrc.el.
15959 The variables are listed below, these values maybe changed as required.
15962 sdcdbsrc-cpu-type '51
15965 sdcdbsrc-frequency '11059200
15968 sdcdbsrc-serial nil
15971 The following is a list of key mapping for the debugger interface.
15979 ;; Current Listing ::
15981 ;;key\SpecialChar ~
15996 binding\SpecialChar ~
16020 ;;---\SpecialChar ~
16035 ------\SpecialChar ~
16075 sdcdb-next-from-src\SpecialChar ~
16101 sdcdb-back-from-src\SpecialChar ~
16127 sdcdb-cont-from-src\SpecialChar ~
16137 SDCDB continue command
16153 sdcdb-step-from-src\SpecialChar ~
16179 sdcdb-whatis-c-sexp\SpecialChar ~
16189 SDCDB ptypecommand for data at
16253 sdcdbsrc-delete\SpecialChar ~
16267 SDCDB Delete all breakpoints if no arg
16315 given or delete arg (C-u arg x)
16331 sdcdbsrc-frame\SpecialChar ~
16346 SDCDB Display current frame if no arg,
16395 given or display frame arg
16460 sdcdbsrc-goto-sdcdb\SpecialChar ~
16470 Goto the SDCDB output buffer
16486 sdcdb-print-c-sexp\SpecialChar ~
16497 SDCDB print command for data at
16561 sdcdbsrc-goto-sdcdb\SpecialChar ~
16571 Goto the SDCDB output buffer
16587 sdcdbsrc-mode\SpecialChar ~
16603 Toggles Sdcdbsrc mode (turns it off)
16607 ;; C-c C-f\SpecialChar ~
16615 sdcdb-finish-from-src\SpecialChar ~
16623 SDCDB finish command
16627 ;; C-x SPC\SpecialChar ~
16635 sdcdb-break\SpecialChar ~
16653 Set break for line with point
16655 ;; ESC t\SpecialChar ~
16665 sdcdbsrc-mode\SpecialChar ~
16681 Toggle Sdcdbsrc mode
16683 ;; ESC m\SpecialChar ~
16693 sdcdbsrc-srcmode\SpecialChar ~
16715 Here are a few guidelines that will help the compiler generate more efficient
16716 code, some of the tips are specific to this compiler others are generally
16717 good programming practice.
16720 Use the smallest data type to represent your data-value.
16721 If it is known in advance that the value is going to be less than 256 then
16722 use an 'unsigned char' instead of a 'short' or 'int'.
16723 Please note, that ANSI C requires both signed and unsigned chars to be
16724 promoted to 'signed int' before doing any operation.
16725 This promotion can be omitted, if the result is the same.
16726 The effect of the promotion rules together with the sign-extension is often
16733 unsigned char uc = 0xfe;
16735 if (uc * uc < 0) /* this is true! */
16754 (int) uc * (int) uc = (int) 0xfe * (int) 0xfe = (int) 0xfc04 = -1024
16764 (unsigned char) -12 / (signed char) -3 = ...
16767 No, the result is not 4:
16772 (int) (unsigned char) -12 / (int) (signed char) -3 =
16774 (int) (unsigned char) 0xf4 / (int) (signed char) 0xfd =
16776 (int) 0x00f4 / (int) 0xfffd =
16778 (int) 0x00f4 / (int) 0xfffd =
16780 (int) 244 / (int) -3 =
16782 (int) -81 = (int) 0xffaf;
16785 Don't complain, that gcc gives you a different result.
16786 gcc uses 32 bit ints, while SDCC uses 16 bit ints.
16787 Therefore the results are different.
16790 \begin_inset Quotes sld
16794 \begin_inset Quotes srd
16800 If well-defined overflow characteristics are important and negative values
16801 are not, or if you want to steer clear of sign-extension problems when
16802 manipulating bits or bytes, use one of the corresponding unsigned types.
16803 (Beware when mixing signed and unsigned values in expressions, though.)
16805 Although character types (especially unsigned char) can be used as "tiny"
16806 integers, doing so is sometimes more trouble than it's worth, due to unpredicta
16807 ble sign extension and increased code size.
16811 Use unsigned when it is known in advance that the value is not going to
16813 This helps especially if you are doing division or multiplication, bit-shifting
16814 or are using an array index.
16817 NEVER jump into a LOOP.
16820 Declare the variables to be local
16821 \begin_inset LatexCommand \index{local variables}
16825 whenever possible, especially loop control variables (induction).
16828 Since the compiler does not always do implicit integral promotion, the programme
16829 r should do an explicit cast when integral promotion is required.
16832 Reducing the size of division, multiplication & modulus operations can reduce
16833 code size substantially.
16834 Take the following code for example.
16840 foobar(unsigned int p1, unsigned char ch)
16848 unsigned char ch1 = p1 % ch ;
16859 For the modulus operation the variable ch will be promoted to unsigned int
16860 first then the modulus operation will be performed (this will lead to a
16861 call to support routine _moduint()), and the result will be casted to a
16863 If the code is changed to
16868 foobar(unsigned int p1, unsigned char ch)
16876 unsigned char ch1 = (unsigned char)p1 % ch ;
16887 It would substantially reduce the code generated (future versions of the
16888 compiler will be smart enough to detect such optimization opportunities).
16892 Have a look at the assembly listing to get a
16893 \begin_inset Quotes sld
16897 \begin_inset Quotes srd
16900 for the code generation.
16904 \begin_inset LatexCommand \index{Tools}
16908 included in the distribution
16912 \begin_inset Tabular
16913 <lyxtabular version="3" rows="12" columns="3">
16915 <column alignment="center" valignment="top" leftline="true" width="0pt">
16916 <column alignment="center" valignment="top" leftline="true" width="0pt">
16917 <column alignment="center" valignment="top" leftline="true" rightline="true" width="0pt">
16918 <row topline="true" bottomline="true">
16919 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
16927 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
16935 <cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
16944 <row topline="true">
16945 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
16953 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
16958 Simulator for various architectures
16961 <cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
16970 <row topline="true">
16971 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
16979 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
16984 header file conversion
16987 <cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
16992 sdcc/support/scripts
16996 <row topline="true">
16997 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
17005 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
17010 header file conversion
17013 <cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
17018 sdcc/support/scripts
17022 <row topline="true">
17023 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
17031 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
17039 <cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
17057 <row topline="true">
17058 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
17066 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
17074 <cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
17092 <row topline="true">
17093 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
17101 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
17109 <cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
17127 <row topline="true">
17128 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
17136 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
17144 <cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
17162 <row topline="true">
17163 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
17171 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
17179 <cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
17197 <row topline="true">
17198 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
17206 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
17214 <cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
17232 <row topline="true">
17233 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
17241 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
17249 <cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
17267 <row topline="true" bottomline="true">
17268 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
17276 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
17284 <cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
17312 \begin_inset LatexCommand \index{Documentation}
17316 included in the distribution
17320 \begin_inset Tabular
17321 <lyxtabular version="3" rows="10" columns="2">
17323 <column alignment="left" valignment="top" leftline="true" width="0">
17324 <column alignment="left" valignment="top" leftline="true" rightline="true" width="0pt">
17325 <row topline="true" bottomline="true">
17326 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
17334 <cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
17339 Where to get / filename
17343 <row topline="true">
17344 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
17349 SDCC Compiler User Guide
17352 <cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
17357 You're reading it right now
17361 <row topline="true">
17362 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
17370 <cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
17379 <row topline="true">
17380 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
17385 ASXXXX Assemblers and ASLINK Relocating Linker
17388 <cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
17393 sdcc/as/doc/asxhtm.html
17397 <row topline="true">
17398 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
17403 SDCC regression test
17404 \begin_inset LatexCommand \index{Regression test}
17411 <cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
17416 sdcc/doc/test_suite_spec.pdf
17420 <row topline="true">
17421 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
17429 <cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
17438 <row topline="true">
17439 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
17444 Notes on debugging with sdcdb
17445 \begin_inset LatexCommand \index{sdcdb (debugger)}
17452 <cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
17457 sdcc/debugger/README
17461 <row topline="true">
17462 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
17467 Software simulator for microcontrollers
17470 <cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
17497 <row topline="true">
17498 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
17503 Temporary notes on the pic16
17504 \begin_inset LatexCommand \index{PIC16}
17511 <cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
17516 sdcc/src/pic16/NOTES
17520 <row topline="true" bottomline="true">
17521 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
17526 SDCC internal documentation (debugging file format)
17529 <cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
17565 Related open source tools
17566 \begin_inset LatexCommand \index{Related tools}
17574 \begin_inset Tabular
17575 <lyxtabular version="3" rows="11" columns="3">
17577 <column alignment="center" valignment="top" leftline="true" width="0pt">
17578 <column alignment="block" valignment="top" leftline="true" width="30line%">
17579 <column alignment="center" valignment="top" leftline="true" rightline="true" width="0pt">
17580 <row topline="true" bottomline="true">
17581 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
17589 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
17597 <cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
17606 <row topline="true">
17607 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
17613 \begin_inset LatexCommand \index{gpsim (pic simulator)}
17620 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
17628 <cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
17634 \begin_inset LatexCommand \url{http://www.dattalo.com/gnupic/gpsim.html}
17642 <row topline="true">
17643 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
17649 \begin_inset LatexCommand \index{gputils (pic tools)}
17656 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
17664 <cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
17670 \begin_inset LatexCommand \url{http://gputils.sourceforge.net/}
17678 <row topline="true">
17679 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
17687 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
17695 <cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
17701 \begin_inset LatexCommand \url{http://digilander.libero.it/fbradasc/FLP5.html}
17709 <row topline="true">
17710 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
17716 \begin_inset LatexCommand \index{indent (source formatting tool)}
17723 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
17728 Formats C source - Master of the white spaces
17731 <cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
17737 \begin_inset LatexCommand \url{http://home.hccnet.nl/d.ingamells/beautify.html}
17745 <row topline="true">
17746 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
17752 \begin_inset LatexCommand \index{srecord (tool)}
17759 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
17764 Object file conversion, checksumming, ...
17767 <cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
17773 \begin_inset LatexCommand \url{http://srecord.sourceforge.net/}
17781 <row topline="true">
17782 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
17788 \begin_inset LatexCommand \index{objdump (tool)}
17795 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
17800 Object file conversion, ...
17803 <cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
17808 Part of binutils (should be there anyway)
17812 <row topline="true">
17813 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
17819 \begin_inset LatexCommand \index{doxygen (source documentation tool)}
17826 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
17831 Source code documentation system
17834 <cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
17840 \begin_inset LatexCommand \url{http://www.doxygen.org}
17848 <row topline="true">
17849 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
17857 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
17862 IDE (has anyone tried integrating SDCC & sdcdb? Unix only)
17865 <cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
17871 \begin_inset LatexCommand \url{http://www.kdevelop.org}
17879 <row topline="true">
17880 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
17886 \begin_inset LatexCommand \index{splint (syntax checking tool)}
17893 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
17898 Statically checks c sources
17901 <cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
17907 \begin_inset LatexCommand \url{http://www.splint.org}
17915 <row topline="true" bottomline="true">
17916 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
17922 \begin_inset LatexCommand \index{ddd (debugger)}
17929 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
17934 Debugger, serves nicely as GUI to sdcdb
17935 \begin_inset LatexCommand \index{sdcdb (debugger)}
17942 <cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
17948 \begin_inset LatexCommand \url{http://www.gnu.org/software/ddd/}
17965 Related documentation / recommended reading
17969 \begin_inset Tabular
17970 <lyxtabular version="3" rows="6" columns="3">
17972 <column alignment="center" valignment="top" leftline="true" width="0pt">
17973 <column alignment="block" valignment="top" leftline="true" width="30line%">
17974 <column alignment="center" valignment="top" leftline="true" rightline="true" width="0pt">
17975 <row topline="true" bottomline="true">
17976 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
17984 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
17992 <cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
18001 <row topline="true">
18002 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
18019 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
18025 \begin_inset LatexCommand \index{C Reference card}
18032 <cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
18038 \begin_inset LatexCommand \url{http://www.refcards.com/about/c.html}
18046 <row topline="true">
18047 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
18055 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
18063 <cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
18069 \begin_inset LatexCommand \url{http://www.eskimo.com/~scs/C-faq/top.html}
18077 <row topline="true">
18078 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
18085 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
18090 Latest datasheet of the target CPU
18093 <cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
18102 <row topline="true">
18103 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
18110 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
18115 Revision history of datasheet
18118 <cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
18127 <row topline="true" bottomline="true">
18128 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
18138 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
18143 Advanced Compiler Design and Implementation
18146 <cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
18151 bookstore (very dedicated, probably read other books first)
18167 Some questions answered, some pointers given - it might be time to in turn
18175 can you solve your project with the selected microcontroller? Would you
18176 find out early or rather late that your target is too small/slow/whatever?
18177 Can you switch to a slightly better device if it doesn't fit?
18180 should you solve the problem with an 8 bit CPU? Or would a 16/32 bit CPU
18181 and/or another programming language be more adequate? Would an operating
18182 system on the target device help?
18185 if you solved the problem, will the marketing department be happy?
18188 if the marketing department is happy, will customers be happy?
18191 if you're the project manager, marketing department and maybe even the customer
18192 in one person, have you tried to see the project from the outside?
18195 is the project done if you think it is done? Or is just that other interface/pro
18196 tocol/feature/configuration/option missing? How about website, manual(s),
18197 internationali(z|s)ation, packaging, labels, 2nd source for components,
18198 electromagnetic compatability/interference, documentation for production,
18199 production test software, update mechanism, patent issues?
18202 is your project adequately positioned in that magic triangle: fame, fortune,
18206 Maybe not all answers to these questions are known and some answers may
18211 , nevertheless knowing these questions may help you to avoid burnout
18217 burnout is bad for electronic devices, programmers and motorcycle tyres
18221 Chances are you didn't want to hear some of them...
18225 \begin_inset LatexCommand \index{Support}
18232 SDCC has grown to be a large project.
18233 The compiler alone (without the preprocessor, assembler and linker) is
18234 well over 100,000 lines of code (blank stripped).
18235 The open source nature of this project is a key to its continued growth
18237 You gain the benefit and support of many active software developers and
18239 Is SDCC perfect? No, that's why we need your help.
18240 The developers take pride in fixing reported bugs.
18241 You can help by reporting the bugs and helping other SDCC users.
18242 There are lots of ways to contribute, and we encourage you to take part
18243 in making SDCC a great software package.
18247 The SDCC project is hosted on the SDCC sourceforge site at
18248 \begin_inset LatexCommand \htmlurl{http://sourceforge.net/projects/sdcc}
18253 You'll find the complete set of mailing lists
18254 \begin_inset LatexCommand \index{Mailing list}
18258 , forums, bug reporting system, patch submission
18259 \begin_inset LatexCommand \index{Patch submission}
18264 \begin_inset LatexCommand \index{download}
18268 area and cvs code repository
18269 \begin_inset LatexCommand \index{cvs code repository}
18277 \begin_inset LatexCommand \index{Bug reporting}
18282 \begin_inset LatexCommand \index{Reporting bugs}
18289 The recommended way of reporting bugs is using the infrastructure of the
18291 You can follow the status of bug reports there and have an overview about
18295 Bug reports are automatically forwarded to the developer mailing list and
18296 will be fixed ASAP.
18297 When reporting a bug, it is very useful to include a small test program
18298 (the smaller the better) which reproduces the problem.
18299 If you can isolate the problem by looking at the generated assembly code,
18300 this can be very helpful.
18301 Compiling your program with the -
18312 \begin_inset LatexCommand \index{-\/-dumpall}
18316 option can sometimes be useful in locating optimization problems.
18317 When reporting a bug please maker sure you:
18320 Attach the code you are compiling with SDCC.
18324 Specify the exact command you use to run SDCC, or attach your Makefile.
18328 Specify the SDCC version (type "
18334 "), your platform, and operating system.
18338 Provide an exact copy of any error message or incorrect output.
18342 Put something meaningful in the subject of your message.
18345 Please attempt to include these 5 important parts, as applicable, in all
18346 requests for support or when reporting any problems or bugs with SDCC.
18347 Though this will make your message lengthy, it will greatly improve your
18348 chance that SDCC users and developers will be able to help you.
18349 Some SDCC developers are frustrated by bug reports without code provided
18350 that they can use to reproduce and ultimately fix the problem, so please
18351 be sure to provide sample code if you are reporting a bug!
18354 Please have a short check that you are using a recent version of SDCC and
18355 the bug is not yet known.
18356 This is the link for reporting bugs:
18357 \begin_inset LatexCommand \htmlurl{http://sourceforge.net/tracker/?group_id=599&atid=100599}
18364 Requesting Features
18365 \begin_inset LatexCommand \label{sub:Requesting-Features}
18370 \begin_inset LatexCommand \index{Feature request}
18375 \begin_inset LatexCommand \index{Requesting features}
18382 Like bug reports feature requests are forwarded to the developer mailing
18384 This is the link for requesting features:
18385 \begin_inset LatexCommand \htmlurl{http://sourceforge.net/tracker/?group_id=599&atid=350599}
18395 Like bug reports contributed patches are forwarded to the developer mailing
18397 This is the link for submitting patches
18398 \begin_inset LatexCommand \index{Patch submission}
18403 \begin_inset LatexCommand \url{http://sourceforge.net/tracker/?group_id=599&atid=300599}
18410 You need to specify some parameters to the
18414 command for the patches to be useful.
18415 If you modified more than one file a patch created f.e.
18420 \begin_inset Quotes sld
18423 diff -Naur unmodified_directory modified_directory >my_changes.patch
18424 \begin_inset Quotes srd
18430 will be fine, otherwise
18434 \begin_inset Quotes sld
18437 diff -u sourcefile.c.orig sourcefile.c >my_changes.patch
18438 \begin_inset Quotes srd
18451 These links should take you directly to the
18452 \begin_inset LatexCommand \url[Mailing lists]{http://sourceforge.net/mail/?group_id=599}
18462 Traffic on sdcc-devel and sdcc-user is about 100 mails/month each not counting
18463 automated messages (mid 2003)
18467 \begin_inset LatexCommand \url[Forums]{http://sourceforge.net/forum/?group_id=599}
18471 , lists and forums are archived and searchable so if you are lucky someone
18472 already had a similar problem.
18478 You can follow the status of the cvs version
18479 \begin_inset LatexCommand \index{version}
18483 of SDCC by watching the Changelog
18484 \begin_inset LatexCommand \index{Changelog}
18488 in the cvs-repository
18493 \begin_inset LatexCommand \htmlurl{http://cvs.sourceforge.net/cgi-bin/viewcvs.cgi/*checkout*/sdcc/sdcc/ChangeLog?rev=HEAD&content-type=text/plain}
18501 \begin_inset LatexCommand \index{Release policy}
18508 Historically there often were long delays between official releases and
18509 the sourceforge download area tends to get not updated at all.
18510 Excuses in the past might have referred to problems with live range analysis,
18511 but as this was fixed a while ago, the current problem is that another
18512 excuse has to be found.
18513 Kidding aside, we have to get better there! On the other hand there are
18514 daily snapshots available at
18515 \begin_inset LatexCommand \htmlurl[snap]{http://sdcc.sourceforge.net/snap.php}
18519 , and you can always build the very last version (hopefully with many bugs
18520 fixed, and features added) from the source code available at
18521 \begin_inset LatexCommand \htmlurl[Source]{http://sdcc.sourceforge.net/snap.php#Source}
18529 \begin_inset LatexCommand \index{Examples}
18536 You'll find some small examples in the directory
18538 sdcc/device/examples/.
18541 More examples and libraries are available at
18543 The SDCC Open Knowledge Resource
18544 \begin_inset LatexCommand \url{http://www.qsl.net/dl9sec/SDCC_OKR.html}
18551 \begin_inset LatexCommand \url{http://www.pjrc.com/tech/8051/}
18558 I did insert a reference to Paul's web site here although it seems rather
18559 dedicated to a specific 8032 board (I think it's okay because it f.e.
18560 shows LCD/Harddisc interface and has a free 8051 monitor.
18561 Independent 8032 board vendors face hard competition of heavily subsidized
18562 development boards anyway).
18565 Maybe we should include some links to real world applications.
18566 Preferably pointer to pointers (one for each architecture) so this stays
18571 \begin_inset LatexCommand \index{Quality control}
18578 The compiler is passed through nightly compile and build checks.
18584 \begin_inset LatexCommand \index{Regression test}
18588 check that SDCC itself compiles flawlessly on several platforms and checks
18589 the quality of the code generated by SDCC by running the code through simulator
18591 There is a separate document
18594 \begin_inset LatexCommand \index{Test suite}
18603 You'll find the test code in the directory
18605 sdcc/support/regression
18608 You can run these tests manually by running
18612 in this directory (or f.e.
18617 \begin_inset Quotes sld
18621 \begin_inset Quotes srd
18627 if you don't want to run the complete tests).
18628 The test code might also be interesting if you want to look for examples
18629 \begin_inset LatexCommand \index{Examples}
18633 checking corner cases of SDCC or if you plan to submit patches
18634 \begin_inset LatexCommand \index{Patch submission}
18641 The pic port uses a different set of regression tests, you'll find them
18644 sdcc/src/regression
18649 SDCC Technical Data
18653 \begin_inset LatexCommand \index{Optimizations}
18660 SDCC performs a host of standard optimizations in addition to some MCU specific
18665 Sub-expression Elimination
18666 \begin_inset LatexCommand \index{Subexpression elimination}
18673 The compiler does local and
18699 will be translated to
18711 Some subexpressions are not as obvious as the above example, e.g.:
18721 In this case the address arithmetic a->b[i] will be computed only once;
18722 the equivalent code in C would be.
18734 The compiler will try to keep these temporary variables in registers.
18737 Dead-Code Elimination
18738 \begin_inset LatexCommand \index{Dead-code elimination}
18759 i = 1; \SpecialChar ~
18768 global = 1;\SpecialChar ~
18781 global = 3;\SpecialChar ~
18810 \begin_inset LatexCommand \index{Copy propagation}
18866 Note: the dead stores created by this copy propagation will be eliminated
18867 by dead-code elimination.
18871 \begin_inset LatexCommand \index{Loop optimization}
18878 Two types of loop optimizations are done by SDCC loop invariant lifting
18879 and strength reduction of loop induction variables.
18880 In addition to the strength reduction the optimizer marks the induction
18881 variables and the register allocator tries to keep the induction variables
18882 in registers for the duration of the loop.
18883 Because of this preference of the register allocator
18884 \begin_inset LatexCommand \index{Register allocation}
18888 , loop induction optimization causes an increase in register pressure, which
18889 may cause unwanted spilling of other temporary variables into the stack
18890 \begin_inset LatexCommand \index{stack}
18895 The compiler will generate a warning message when it is forced to allocate
18896 extra space either on the stack or data space.
18897 If this extra space allocation is undesirable then induction optimization
18898 can be eliminated either for the entire source file (with -
18908 -noinduction option) or for a given function only using #pragma\SpecialChar ~
18910 \begin_inset LatexCommand \index{\#pragma noinduction}
18923 for (i = 0 ; i < 100 ; i ++)
18939 for (i = 0; i < 100; i++)
18948 As mentioned previously some loop invariants are not as apparent, all static
18949 address computations are also moved out of the loop.
18954 \begin_inset LatexCommand \index{Strength reduction}
18958 , this optimization substitutes an expression by a cheaper expression:
18963 for (i=0;i < 100; i++)
18981 for (i=0;i< 100;i++) {
18987 ar[itemp1] = itemp2;
19004 The more expensive multiplication
19005 \begin_inset LatexCommand \index{Multiplication}
19009 is changed to a less expensive addition.
19013 \begin_inset LatexCommand \index{Loop reversing}
19020 This optimization is done to reduce the overhead of checking loop boundaries
19021 for every iteration.
19022 Some simple loops can be reversed and implemented using a
19023 \begin_inset Quotes eld
19026 decrement and jump if not zero
19027 \begin_inset Quotes erd
19031 SDCC checks for the following criterion to determine if a loop is reversible
19032 (note: more sophisticated compilers use data-dependency analysis to make
19033 this determination, SDCC uses a more simple minded analysis).
19036 The 'for' loop is of the form
19042 for(<symbol> = <expression>; <sym> [< | <=] <expression>; [<sym>++ | <sym>
19052 The <for body> does not contain
19053 \begin_inset Quotes eld
19057 \begin_inset Quotes erd
19061 \begin_inset Quotes erd
19067 All goto's are contained within the loop.
19070 No function calls within the loop.
19073 The loop control variable <sym> is not assigned any value within the loop
19076 The loop control variable does NOT participate in any arithmetic operation
19080 There are NO switch statements in the loop.
19083 Algebraic Simplifications
19086 SDCC does numerous algebraic simplifications, the following is a small sub-set
19087 of these optimizations.
19092 i = j + 0;\SpecialChar ~
19096 /* changed to: */\SpecialChar ~
19102 i /= 2;\SpecialChar ~
19109 /* changed to: */\SpecialChar ~
19115 i = j - j;\SpecialChar ~
19119 /* changed to: */\SpecialChar ~
19125 i = j / 1;\SpecialChar ~
19129 /* changed to: */\SpecialChar ~
19136 Note the subexpressions
19137 \begin_inset LatexCommand \index{Subexpression}
19141 given above are generally introduced by macro expansions or as a result
19142 of copy/constant propagation.
19145 'switch' Statements
19146 \begin_inset LatexCommand \label{sub:'switch'-Statements}
19151 \begin_inset LatexCommand \index{switch statement}
19158 SDCC changes switch statements to jump tables
19159 \begin_inset LatexCommand \index{jump tables}
19163 when the following conditions are true.
19167 The case labels are in numerical sequence, the labels need not be in order,
19168 and the starting number need not be one or zero.
19174 switch(i) {\SpecialChar ~
19205 case 4: ...\SpecialChar ~
19237 case 5: ...\SpecialChar ~
19269 case 3: ...\SpecialChar ~
19301 case 6: ...\SpecialChar ~
19369 Both the above switch statements will be implemented using a jump-table.
19370 The example to the right side is slightly more efficient as the check for
19371 the lower boundary of the jump-table is not needed.
19375 The number of case labels is at least three, since it takes two conditional
19376 statements to handle the boundary conditions.
19379 The number of case labels is less than 84, since each label takes 3 bytes
19380 and a jump-table can be utmost 256 bytes long.
19383 Switch statements which have gaps in the numeric sequence or those that
19384 have more that 84 case labels can be split into more than one switch statement
19385 for efficient code generation, e.g.:
19435 If the above switch statement is broken down into two switch statements
19474 case 9:\SpecialChar ~
19481 case 10:\SpecialChar ~
19487 case 11:\SpecialChar ~
19493 case 12:\SpecialChar ~
19500 then both the switch statements will be implemented using jump-tables whereas
19501 the unmodified switch statement will not be.
19502 You might also consider inserting dummy cases 0 and 5 to 8 in this example.
19505 The pragma nojtbound
19506 \begin_inset LatexCommand \index{\#pragma nojtbound}
19510 can be used to turn off checking the
19523 It has no effect if a default label is supplied.
19524 Use of this pragma is dangerous: if the switch argument is not matched
19525 by a case statement the processor will happily jump into Nirvana.
19528 Bit-shifting Operations
19529 \begin_inset LatexCommand \index{Bit shifting}
19536 Bit shifting is one of the most frequently used operation in embedded programmin
19538 SDCC tries to implement bit-shift operations in the most efficient way
19554 generates the following code:
19571 In general SDCC will never setup a loop if the shift count is known.
19614 \begin_inset LatexCommand \index{Bit rotation}
19621 A special case of the bit-shift operation is bit rotation
19622 \begin_inset LatexCommand \index{rotating bits}
19626 , SDCC recognizes the following expression to be a left bit-rotation:
19636 char i;\SpecialChar ~
19647 /* unsigned is needed for rotation */
19652 i = ((i << 1) | (i >> 7));
19661 will generate the following code:
19680 SDCC uses pattern matching on the parse tree to determine this operation.Variatio
19681 ns of this case will also be recognized as bit-rotation, i.e.:
19686 i = ((i >> 7) | (i << 1)); /* left-bit rotation */
19689 Nibble and Byte Swapping
19692 Other special cases of the bit-shift operations are nibble or byte swapping
19693 \begin_inset LatexCommand \index{swapping nibbles/bytes}
19697 , SDCC recognizes the following expressions:
19720 i = ((i << 4) | (i >> 4));
19726 j = ((j << 8) | (j >> 8));
19729 and generates a swap instruction for the nibble swapping
19730 \begin_inset LatexCommand \index{Nibble swapping}
19734 or move instructions for the byte swapping
19735 \begin_inset LatexCommand \index{Byte swapping}
19741 \begin_inset Quotes sld
19745 \begin_inset Quotes srd
19748 example can be used to convert from little to big-endian or vice versa.
19749 If you want to change the endianness of a
19753 integer you have to cast to
19760 Note that SDCC stores numbers in little-endian
19766 Usually 8-bit processors don't care much about endianness.
19767 This is not the case for the standard 8051 which only has an instruction
19773 \begin_inset LatexCommand \index{DPTR}
19781 so little-endian is the more efficient byte order.
19785 \begin_inset LatexCommand \index{little-endian}
19790 \begin_inset LatexCommand \index{Endianness}
19795 lowest order first).
19799 \begin_inset LatexCommand \index{Highest Order Bit}
19806 It is frequently required to obtain the highest order bit of an integral
19807 type (long, int, short or char types).
19808 SDCC recognizes the following expression to yield the highest order bit
19809 and generates optimized code for it, e.g.:
19831 hob = (gint >> 15) & 1;
19841 will generate the following code:
19874 000A E5*01\SpecialChar ~
19901 000C 23\SpecialChar ~
19932 000D 54 01\SpecialChar ~
19959 000F F5*02\SpecialChar ~
19987 Variations of this case however will
19992 It is a standard C expression, so I heartily recommend this be the only
19993 way to get the highest order bit, (it is portable).
19994 Of course it will be recognized even if it is embedded in other expressions,
20000 xyz = gint + ((gint >> 15) & 1);
20003 will still be recognized.
20007 \begin_inset LatexCommand \label{sub:Peephole-Optimizer}
20012 \begin_inset LatexCommand \index{Peephole optimizer}
20019 The compiler uses a rule based, pattern matching and re-writing mechanism
20020 for peep-hole optimization.
20025 a peep-hole optimizer by Christopher W.
20026 Fraser (cwfraser@microsoft.com).
20027 A default set of rules are compiled into the compiler, additional rules
20028 may be added with the
20041 \begin_inset LatexCommand \index{-\/-peep-file}
20048 The rule language is best illustrated with examples.
20072 The above rule will change the following assembly
20073 \begin_inset LatexCommand \index{Assembler routines}
20095 Note: All occurrences of a
20099 (pattern variable) must denote the same string.
20100 With the above rule, the assembly sequence:
20110 will remain unmodified.
20114 Other special case optimizations may be added by the user (via
20130 some variants of the 8051 MCU allow only
20139 The following two rules will change all
20158 replace { lcall %1 } by { acall %1 }
20160 replace { ljmp %1 } by { ajmp %1 }
20165 inline-assembler code
20167 is also passed through the peep hole optimizer, thus the peephole optimizer
20168 can also be used as an assembly level macro expander.
20169 The rules themselves are MCU dependent whereas the rule language infra-structur
20170 e is MCU independent.
20171 Peephole optimization rules for other MCU can be easily programmed using
20176 The syntax for a rule is as follows:
20181 rule := replace [ restart ] '{' <assembly sequence> '
20219 <assembly sequence> '
20237 '}' [if <functionName> ] '
20242 <assembly sequence> := assembly instruction (each instruction including
20243 labels must be on a separate line).
20247 The optimizer will apply to the rules one by one from the top in the sequence
20248 of their appearance, it will terminate when all rules are exhausted.
20249 If the 'restart' option is specified, then the optimizer will start matching
20250 the rules again from the top, this option for a rule is expensive (performance)
20251 , it is intended to be used in situations where a transformation will trigger
20252 the same rule again.
20253 An example of this (not a good one, it has side effects) is the following
20276 Note that the replace pattern cannot be a blank, but can be a comment line.
20277 Without the 'restart' option only the innermost 'pop' 'push' pair would
20278 be eliminated, i.e.:
20308 the restart option the rule will be applied again to the resulting code
20309 and then all the pop-push pairs will be eliminated to yield:
20319 A conditional function can be attached to a rule.
20320 Attaching rules are somewhat more involved, let me illustrate this with
20347 The optimizer does a look-up of a function name table defined in function
20352 in the source file SDCCpeeph.c, with the name
20357 If it finds a corresponding entry the function is called.
20358 Note there can be no parameters specified for these functions, in this
20363 is crucial, since the function
20367 expects to find the label in that particular variable (the hash table containin
20368 g the variable bindings is passed as a parameter).
20369 If you want to code more such functions, take a close look at the function
20370 labelInRange and the calling mechanism in source file SDCCpeeph.c.
20371 Currently implemented are
20373 labelInRange, labelRefCount, labelIsReturnOnly, operandsNotSame, xramMovcOption,
20374 24bitMode, portIsDS390, 24bitModeAndPortDS390
20383 I know this whole thing is a little kludgey, but maybe some day we will
20384 have some better means.
20385 If you are looking at this file, you will see the default rules that are
20386 compiled into the compiler, you can add your own rules in the default set
20387 there if you get tired of specifying the -
20401 \begin_inset LatexCommand \index{ANSI-compliance}
20406 \begin_inset LatexCommand \label{sub:ANSI-Compliance}
20413 Deviations from the compliance:
20416 functions are not always reentrant
20417 \begin_inset LatexCommand \index{reentrant}
20424 structures cannot be assigned values directly, cannot be passed as function
20425 parameters or assigned to each other and cannot be a return value from
20452 s1 = s2 ; /* is invalid in SDCC although allowed in ANSI */
20463 struct s foo1 (struct s parms) /* invalid in SDCC although allowed in ANSI
20485 return rets;/* is invalid in SDCC although allowed in ANSI */
20492 \begin_inset LatexCommand \index{long long (not supported)}
20497 \begin_inset LatexCommand \index{int (64 bit) (not supported)}
20505 \begin_inset LatexCommand \index{double (not supported)}
20509 ' precision floating point
20510 \begin_inset LatexCommand \index{Floating point support}
20517 No support for setjmp
20518 \begin_inset LatexCommand \index{setjmp (not supported)}
20523 \begin_inset LatexCommand \index{longjmp (not supported)}
20531 \begin_inset LatexCommand \index{K\&R style}
20535 function declarations are NOT allowed.
20541 foo(i,j) /* this old style of function declarations */
20543 int i,j; /* are valid in ANSI but not valid in SDCC */
20558 functions declared as pointers
20559 \begin_inset LatexCommand \index{Pointer (to function)}
20564 \begin_inset LatexCommand \index{function pointers}
20568 must be dereferenced during the call.
20579 /* has to be called like this */
20581 (*foo)(); /* ANSI standard allows calls to be made like 'foo()' */
20585 Cyclomatic Complexity
20586 \begin_inset LatexCommand \index{Cyclomatic complexity}
20593 Cyclomatic complexity of a function is defined as the number of independent
20594 paths the program can take during execution of the function.
20595 This is an important number since it defines the number test cases you
20596 have to generate to validate the function.
20597 The accepted industry standard for complexity number is 10, if the cyclomatic
20598 complexity reported by SDCC exceeds 10 you should think about simplification
20599 of the function logic.
20600 Note that the complexity level is not related to the number of lines of
20601 code in a function.
20602 Large functions can have low complexity, and small functions can have large
20608 SDCC uses the following formula to compute the complexity:
20613 complexity = (number of edges in control flow graph) - (number of nodes
20614 in control flow graph) + 2;
20618 Having said that the industry standard is 10, you should be aware that in
20619 some cases it be may unavoidable to have a complexity level of less than
20621 For example if you have switch statement with more than 10 case labels,
20622 each case label adds one to the complexity level.
20623 The complexity level is by no means an absolute measure of the algorithmic
20624 complexity of the function, it does however provide a good starting point
20625 for which functions you might look at for further optimization.
20628 Retargetting for other Processors
20631 The issues for retargetting the compiler are far too numerous to be covered
20633 What follows is a brief description of each of the seven phases of the
20634 compiler and its MCU dependency.
20637 Parsing the source and building the annotated parse tree.
20638 This phase is largely MCU independent (except for the language extensions).
20639 Syntax & semantic checks are also done in this phase, along with some initial
20640 optimizations like back patching labels and the pattern matching optimizations
20641 like bit-rotation etc.
20644 The second phase involves generating an intermediate code which can be easy
20645 manipulated during the later phases.
20646 This phase is entirely MCU independent.
20647 The intermediate code generation assumes the target machine has unlimited
20648 number of registers, and designates them with the name iTemp.
20649 The compiler can be made to dump a human readable form of the code generated
20663 This phase does the bulk of the standard optimizations and is also MCU independe
20665 This phase can be broken down into several sub-phases:
20669 Break down intermediate code (iCode) into basic blocks.
20671 Do control flow & data flow analysis on the basic blocks.
20673 Do local common subexpression elimination, then global subexpression elimination
20675 Dead code elimination
20679 If loop optimizations caused any changes then do 'global subexpression eliminati
20680 on' and 'dead code elimination' again.
20683 This phase determines the live-ranges; by live range I mean those iTemp
20684 variables defined by the compiler that still survive after all the optimization
20686 Live range analysis
20687 \begin_inset LatexCommand \index{Live range analysis}
20691 is essential for register allocation, since these computation determines
20692 which of these iTemps will be assigned to registers, and for how long.
20695 Phase five is register allocation.
20696 There are two parts to this process.
20700 The first part I call 'register packing' (for lack of a better term).
20701 In this case several MCU specific expression folding is done to reduce
20706 The second part is more MCU independent and deals with allocating registers
20707 to the remaining live ranges.
20708 A lot of MCU specific code does creep into this phase because of the limited
20709 number of index registers available in the 8051.
20712 The Code generation phase is (unhappily), entirely MCU dependent and very
20713 little (if any at all) of this code can be reused for other MCU.
20714 However the scheme for allocating a homogenized assembler operand for each
20715 iCode operand may be reused.
20718 As mentioned in the optimization section the peep-hole optimizer is rule
20719 based system, which can reprogrammed for other MCUs.
20723 \begin_inset LatexCommand \index{Compiler internals}
20730 The anatomy of the compiler
20731 \begin_inset LatexCommand \label{sub:The-anatomy-of}
20740 This is an excerpt from an article published in Circuit Cellar Magazine
20742 It's a little outdated (the compiler is much more efficient now and user/develo
20743 per friendly), but pretty well exposes the guts of it all.
20749 The current version of SDCC can generate code for Intel 8051 and Z80 MCU.
20750 It is fairly easy to retarget for other 8-bit MCU.
20751 Here we take a look at some of the internals of the compiler.
20756 \begin_inset LatexCommand \index{Parsing}
20763 Parsing the input source file and creating an AST (Annotated Syntax Tree
20764 \begin_inset LatexCommand \index{Annotated syntax tree}
20769 This phase also involves propagating types (annotating each node of the
20770 parse tree with type information) and semantic analysis.
20771 There are some MCU specific parsing rules.
20772 For example the storage classes, the extended storage classes are MCU specific
20773 while there may be a xdata storage class for 8051 there is no such storage
20774 class for z80 or Atmel AVR.
20775 SDCC allows MCU specific storage class extensions, i.e.
20776 xdata will be treated as a storage class specifier when parsing 8051 C
20777 code but will be treated as a C identifier when parsing z80 or ATMEL AVR
20782 \begin_inset LatexCommand \index{iCode}
20789 Intermediate code generation.
20790 In this phase the AST is broken down into three-operand form (iCode).
20791 These three operand forms are represented as doubly linked lists.
20792 ICode is the term given to the intermediate form generated by the compiler.
20793 ICode example section shows some examples of iCode generated for some simple
20794 C source functions.
20798 \begin_inset LatexCommand \index{Optimizations}
20805 Bulk of the target independent optimizations is performed in this phase.
20806 The optimizations include constant propagation, common sub-expression eliminati
20807 on, loop invariant code movement, strength reduction of loop induction variables
20808 and dead-code elimination.
20811 Live range analysis
20812 \begin_inset LatexCommand \index{Live range analysis}
20819 During intermediate code generation phase, the compiler assumes the target
20820 machine has infinite number of registers and generates a lot of temporary
20822 The live range computation determines the lifetime of each of these compiler-ge
20823 nerated temporaries.
20824 A picture speaks a thousand words.
20825 ICode example sections show the live range annotations for each of the
20827 It is important to note here, each iCode is assigned a number in the order
20828 of its execution in the function.
20829 The live ranges are computed in terms of these numbers.
20830 The from number is the number of the iCode which first defines the operand
20831 and the to number signifies the iCode which uses this operand last.
20834 Register Allocation
20835 \begin_inset LatexCommand \index{Register allocation}
20842 The register allocation determines the type and number of registers needed
20844 In most MCUs only a few registers can be used for indirect addressing.
20845 In case of 8051 for example the registers R0 & R1 can be used to indirectly
20846 address the internal ram and DPTR to indirectly address the external ram.
20847 The compiler will try to allocate the appropriate register to pointer variables
20849 ICode example section shows the operands annotated with the registers assigned
20851 The compiler will try to keep operands in registers as much as possible;
20852 there are several schemes the compiler uses to do achieve this.
20853 When the compiler runs out of registers the compiler will check to see
20854 if there are any live operands which is not used or defined in the current
20855 basic block being processed, if there are any found then it will push that
20856 operand and use the registers in this block, the operand will then be popped
20857 at the end of the basic block.
20861 There are other MCU specific considerations in this phase.
20862 Some MCUs have an accumulator; very short-lived operands could be assigned
20863 to the accumulator instead of a general-purpose register.
20869 Figure II gives a table of iCode operations supported by the compiler.
20870 The code generation involves translating these operations into corresponding
20871 assembly code for the processor.
20872 This sounds overly simple but that is the essence of code generation.
20873 Some of the iCode operations are generated on a MCU specific manner for
20874 example, the z80 port does not use registers to pass parameters so the
20875 SEND and RECV iCode operations will not be generated, and it also does
20876 not support JUMPTABLES.
20883 <Where is Figure II ?>
20887 \begin_inset LatexCommand \index{iCode}
20894 This section shows some details of iCode.
20895 The example C code does not do anything useful; it is used as an example
20896 to illustrate the intermediate code generated by the compiler.
20908 /* This function does nothing useful.
20915 for the purpose of explaining iCode */
20918 short function (data int *x)
20926 short i=10; \SpecialChar ~
20928 /* dead initialization eliminated */
20933 short sum=10; /* dead initialization eliminated */
20946 while (*x) *x++ = *p++;
20960 /* compiler detects i,j to be induction variables */
20964 for (i = 0, j = 10 ; i < 10 ; i++, j
20990 mul += i * 3; \SpecialChar ~
20992 /* this multiplication remains */
20998 gint += j * 3;\SpecialChar ~
21000 /* this multiplication changed to addition */
21014 In addition to the operands each iCode contains information about the filename
21015 and line it corresponds to in the source file.
21016 The first field in the listing should be interpreted as follows:
21021 Filename(linenumber: iCode Execution sequence number : ICode hash table
21022 key : loop depth of the iCode).
21027 Then follows the human readable form of the ICode operation.
21028 Each operand of this triplet form can be of three basic types a) compiler
21029 generated temporary b) user defined variable c) a constant value.
21030 Note that local variables and parameters are replaced by compiler generated
21033 \begin_inset LatexCommand \index{Live range analysis}
21037 are computed only for temporaries (i.e.
21038 live ranges are not computed for global variables).
21040 \begin_inset LatexCommand \index{Register allocation}
21044 are allocated for temporaries only.
21045 Operands are formatted in the following manner:
21050 Operand Name [lr live-from : live-to ] { type information } [ registers
21056 As mentioned earlier the live ranges are computed in terms of the execution
21057 sequence number of the iCodes, for example
21059 the iTemp0 is live from (i.e.
21060 first defined in iCode with execution sequence number 3, and is last used
21061 in the iCode with sequence number 5).
21062 For induction variables such as iTemp21 the live range computation extends
21063 the lifetime from the start to the end of the loop.
21065 The register allocator used the live range information to allocate registers,
21066 the same registers may be used for different temporaries if their live
21067 ranges do not overlap, for example r0 is allocated to both iTemp6 and to
21068 iTemp17 since their live ranges do not overlap.
21069 In addition the allocator also takes into consideration the type and usage
21070 of a temporary, for example itemp6 is a pointer to near space and is used
21071 as to fetch data from (i.e.
21072 used in GET_VALUE_AT_ADDRESS) so it is allocated a pointer register (r0).
21073 Some short lived temporaries are allocated to special registers which have
21074 meaning to the code generator e.g.
21075 iTemp13 is allocated to a pseudo register CC which tells the back end that
21076 the temporary is used only for a conditional jump the code generation makes
21077 use of this information to optimize a compare and jump ICode.
21079 There are several loop optimizations
21080 \begin_inset LatexCommand \index{Loop optimization}
21084 performed by the compiler.
21085 It can detect induction variables iTemp21(i) and iTemp23(j).
21086 Also note the compiler does selective strength reduction
21087 \begin_inset LatexCommand \index{Strength reduction}
21092 the multiplication of an induction variable in line 18 (gint = j * 3) is
21093 changed to addition, a new temporary iTemp17 is allocated and assigned
21094 a initial value, a constant 3 is then added for each iteration of the loop.
21095 The compiler does not change the multiplication
21096 \begin_inset LatexCommand \index{Multiplication}
21100 in line 17 however since the processor does support an 8 * 8 bit multiplication.
21102 Note the dead code elimination
21103 \begin_inset LatexCommand \index{Dead-code elimination}
21107 optimization eliminated the dead assignments in line 7 & 8 to I and sum
21115 Sample.c (5:1:0:0) _entry($9) :
21120 Sample.c(5:2:1:0) proc _function [lr0:0]{function short}
21125 Sample.c(11:3:2:0) iTemp0 [lr3:5]{_near * int}[r2] = recv
21130 Sample.c(11:4:53:0) preHeaderLbl0($11) :
21135 Sample.c(11:5:55:0) iTemp6 [lr5:16]{_near * int}[r0] := iTemp0 [lr3:5]{_near
21141 Sample.c(11:6:5:1) _whilecontinue_0($1) :
21146 Sample.c(11:7:7:1) iTemp4 [lr7:8]{int}[r2 r3] = @[iTemp6 [lr5:16]{_near *
21152 Sample.c(11:8:8:1) if iTemp4 [lr7:8]{int}[r2 r3] == 0 goto _whilebreak_0($3)
21157 Sample.c(11:9:14:1) iTemp7 [lr9:13]{_far * int}[DPTR] := _p [lr0:0]{_far
21163 Sample.c(11:10:15:1) _p [lr0:0]{_far * int} = _p [lr0:0]{_far * int} + 0x2
21169 Sample.c(11:13:18:1) iTemp10 [lr13:14]{int}[r2 r3] = @[iTemp7 [lr9:13]{_far
21175 Sample.c(11:14:19:1) *(iTemp6 [lr5:16]{_near * int}[r0]) := iTemp10 [lr13:14]{int
21181 Sample.c(11:15:12:1) iTemp6 [lr5:16]{_near * int}[r0] = iTemp6 [lr5:16]{_near
21182 * int}[r0] + 0x2 {short}
21187 Sample.c(11:16:20:1) goto _whilecontinue_0($1)
21192 Sample.c(11:17:21:0)_whilebreak_0($3) :
21197 Sample.c(12:18:22:0) iTemp2 [lr18:40]{short}[r2] := 0x0 {short}
21202 Sample.c(13:19:23:0) iTemp11 [lr19:40]{short}[r3] := 0x0 {short}
21207 Sample.c(15:20:54:0)preHeaderLbl1($13) :
21212 Sample.c(15:21:56:0) iTemp21 [lr21:38]{short}[r4] := 0x0 {short}
21217 Sample.c(15:22:57:0) iTemp23 [lr22:38]{int}[r5 r6] := 0xa {int}
21222 Sample.c(15:23:58:0) iTemp17 [lr23:38]{int}[r7 r0] := 0x1e {int}
21227 Sample.c(15:24:26:1)_forcond_0($4) :
21232 Sample.c(15:25:27:1) iTemp13 [lr25:26]{char}[CC] = iTemp21 [lr21:38]{short}[r4]
21238 Sample.c(15:26:28:1) if iTemp13 [lr25:26]{char}[CC] == 0 goto _forbreak_0($7)
21243 Sample.c(16:27:31:1) iTemp2 [lr18:40]{short}[r2] = iTemp2 [lr18:40]{short}[r2]
21244 + ITemp21 [lr21:38]{short}[r4]
21249 Sample.c(17:29:33:1) iTemp15 [lr29:30]{short}[r1] = iTemp21 [lr21:38]{short}[r4]
21255 Sample.c(17:30:34:1) iTemp11 [lr19:40]{short}[r3] = iTemp11 [lr19:40]{short}[r3]
21256 + iTemp15 [lr29:30]{short}[r1]
21261 Sample.c(18:32:36:1:1) iTemp17 [lr23:38]{int}[r7 r0]= iTemp17 [lr23:38]{int}[r7
21267 Sample.c(18:33:37:1) _gint [lr0:0]{int} = _gint [lr0:0]{int} + iTemp17 [lr23:38]{
21273 Sample.c(15:36:42:1) iTemp21 [lr21:38]{short}[r4] = iTemp21 [lr21:38]{short}[r4]
21279 Sample.c(15:37:45:1) iTemp23 [lr22:38]{int}[r5 r6]= iTemp23 [lr22:38]{int}[r5
21285 Sample.c(19:38:47:1) goto _forcond_0($4)
21290 Sample.c(19:39:48:0)_forbreak_0($7) :
21295 Sample.c(20:40:49:0) iTemp24 [lr40:41]{short}[DPTR] = iTemp2 [lr18:40]{short}[r2]
21296 + ITemp11 [lr19:40]{short}[r3]
21301 Sample.c(20:41:50:0) ret iTemp24 [lr40:41]{short}
21306 Sample.c(20:42:51:0)_return($8) :
21311 Sample.c(20:43:52:0) eproc _function [lr0:0]{ ia0 re0 rm0}{function short}
21317 Finally the code generated for this function:
21358 ; ----------------------------------------------
21363 ; function function
21368 ; ----------------------------------------------
21378 ; iTemp0 [lr3:5]{_near * int}[r2] = recv
21390 ; iTemp6 [lr5:16]{_near * int}[r0] := iTemp0 [lr3:5]{_near * int}[r2]
21402 ;_whilecontinue_0($1) :
21412 ; iTemp4 [lr7:8]{int}[r2 r3] = @[iTemp6 [lr5:16]{_near * int}[r0]]
21417 ; if iTemp4 [lr7:8]{int}[r2 r3] == 0 goto _whilebreak_0($3)
21476 ; iTemp7 [lr9:13]{_far * int}[DPTR] := _p [lr0:0]{_far * int}
21495 ; _p [lr0:0]{_far * int} = _p [lr0:0]{_far * int} + 0x2 {short}
21542 ; iTemp10 [lr13:14]{int}[r2 r3] = @[iTemp7 [lr9:13]{_far * int}[DPTR]]
21582 ; *(iTemp6 [lr5:16]{_near * int}[r0]) := iTemp10 [lr13:14]{int}[r2 r3]
21608 ; iTemp6 [lr5:16]{_near * int}[r0] =
21613 ; iTemp6 [lr5:16]{_near * int}[r0] +
21630 ; goto _whilecontinue_0($1)
21642 ; _whilebreak_0($3) :
21652 ; iTemp2 [lr18:40]{short}[r2] := 0x0 {short}
21664 ; iTemp11 [lr19:40]{short}[r3] := 0x0 {short}
21676 ; iTemp21 [lr21:38]{short}[r4] := 0x0 {short}
21688 ; iTemp23 [lr22:38]{int}[r5 r6] := 0xa {int}
21707 ; iTemp17 [lr23:38]{int}[r7 r0] := 0x1e {int}
21736 ; iTemp13 [lr25:26]{char}[CC] = iTemp21 [lr21:38]{short}[r4] < 0xa {short}
21741 ; if iTemp13 [lr25:26]{char}[CC] == 0 goto _forbreak_0($7)
21786 ; iTemp2 [lr18:40]{short}[r2] = iTemp2 [lr18:40]{short}[r2] +
21791 ; iTemp21 [lr21:38]{short}[r4]
21817 ; iTemp15 [lr29:30]{short}[r1] = iTemp21 [lr21:38]{short}[r4] * 0x3 {short}
21850 ; iTemp11 [lr19:40]{short}[r3] = iTemp11 [lr19:40]{short}[r3] +
21855 ; iTemp15 [lr29:30]{short}[r1]
21874 ; iTemp17 [lr23:38]{int}[r7 r0]= iTemp17 [lr23:38]{int}[r7 r0]- 0x3 {short}
21921 ; _gint [lr0:0]{int} = _gint [lr0:0]{int} + iTemp17 [lr23:38]{int}[r7 r0]
21968 ; iTemp21 [lr21:38]{short}[r4] = iTemp21 [lr21:38]{short}[r4] + 0x1 {short}
21980 ; iTemp23 [lr22:38]{int}[r5 r6]= iTemp23 [lr22:38]{int}[r5 r6]- 0x1 {short}
21994 cjne r5,#0xff,00104$
22006 ; goto _forcond_0($4)
22018 ; _forbreak_0($7) :
22028 ; ret iTemp24 [lr40:41]{short}
22071 A few words about basic block successors, predecessors and dominators
22074 Successors are basic blocks
22075 \begin_inset LatexCommand \index{Basic blocks}
22079 that might execute after this basic block.
22081 Predecessors are basic blocks that might execute before reaching this basic
22084 Dominators are basic blocks that WILL execute before reaching this basic
22118 a) succList of [BB2] = [BB4], of [BB3] = [BB4], of [BB1] = [BB2,BB3]
22121 b) predList of [BB2] = [BB1], of [BB3] = [BB1], of [BB4] = [BB2,BB3]
22124 c) domVect of [BB4] = BB1 ...
22125 here we are not sure if BB2 or BB3 was executed but we are SURE that BB1
22133 \begin_inset LatexCommand \url{http://sdcc.sourceforge.net#Who}
22143 Thanks to all the other volunteer developers who have helped with coding,
22144 testing, web-page creation, distribution sets, etc.
22145 You know who you are :-)
22152 This document was initially written by Sandeep Dutta
22155 All product names mentioned herein may be trademarks
22156 \begin_inset LatexCommand \index{Trademarks}
22160 of their respective companies.
22167 To avoid confusion, the installation and building options for SDCC itself
22168 (chapter 2) are not part of the index.
22172 \begin_inset LatexCommand \printindex{}