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
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 the documentation of srecord
4232 \begin_inset LatexCommand \index{srecord (tool)}
4240 \begin_inset LatexCommand \index{.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{.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{.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 Command Line Options
4572 \begin_inset LatexCommand \index{Command Line Options}
4579 Processor Selection Options
4580 \begin_inset LatexCommand \index{Options processor selection}
4585 \begin_inset LatexCommand \index{Processor selection options}
4591 \labelwidthstring 00.00.0000
4596 \begin_inset LatexCommand \index{-mmcs51}
4602 Generate code for the Intel MCS51
4603 \begin_inset LatexCommand \index{MCS51}
4607 family of processors.
4608 This is the default processor target.
4610 \labelwidthstring 00.00.0000
4615 \begin_inset LatexCommand \index{-mds390}
4621 Generate code for the Dallas DS80C390
4622 \begin_inset LatexCommand \index{DS80C390}
4628 \labelwidthstring 00.00.0000
4633 \begin_inset LatexCommand \index{-mds400}
4639 Generate code for the Dallas DS80C400
4640 \begin_inset LatexCommand \index{DS80C400}
4646 \labelwidthstring 00.00.0000
4651 \begin_inset LatexCommand \index{-mhc08}
4657 Generate code for the Motorola HC08
4658 \begin_inset LatexCommand \index{HC08}
4662 family of processors (added Oct 2003).
4664 \labelwidthstring 00.00.0000
4669 \begin_inset LatexCommand \index{-mz80}
4675 Generate code for the Zilog Z80
4676 \begin_inset LatexCommand \index{Z80}
4680 family of processors.
4682 \labelwidthstring 00.00.0000
4687 \begin_inset LatexCommand \index{-mgbz80}
4693 Generate code for the GameBoy Z80
4694 \begin_inset LatexCommand \index{gbz80 (GameBoy Z80)}
4698 processor (Not actively maintained).
4700 \labelwidthstring 00.00.0000
4705 \begin_inset LatexCommand \index{-mavr}
4711 Generate code for the Atmel AVR
4712 \begin_inset LatexCommand \index{AVR}
4716 processor (In development, not complete).
4717 AVR users should probably have a look at avr-gcc
4718 \begin_inset LatexCommand \url{ http://savannah.nongnu.org/download/avr-libc/snapshots/}
4725 I think it is fair to direct users there for now.
4726 Open source is also about avoiding unnecessary work .
4727 But I didn't find the 'official' link.
4729 \labelwidthstring 00.00.0000
4734 \begin_inset LatexCommand \index{-mpic14}
4740 Generate code for the Microchip PIC 14
4741 \begin_inset LatexCommand \index{PIC14}
4745 -bit processors (p16f84 and variants.
4746 In development, not complete).
4749 p16f627 p16f628 p16f84 p16f873 p16f877?
4751 \labelwidthstring 00.00.0000
4756 \begin_inset LatexCommand \index{-mpic16}
4762 Generate code for the Microchip PIC 16
4763 \begin_inset LatexCommand \index{PIC16}
4767 -bit processors (p18f452 and variants.
4768 In development, not complete).
4770 \labelwidthstring 00.00.0000
4776 Generate code for the Toshiba TLCS-900H
4777 \begin_inset LatexCommand \index{TLCS-900H}
4781 processor (Not maintained, not complete).
4783 \labelwidthstring 00.00.0000
4788 \begin_inset LatexCommand \index{-mxa51}
4794 Generate code for the Phillips XA51
4795 \begin_inset LatexCommand \index{XA51}
4799 processor (Not maintained, not complete).
4802 Preprocessor Options
4803 \begin_inset LatexCommand \index{Options preprocessor}
4808 \begin_inset LatexCommand \index{Preprocessor options}
4813 \begin_inset LatexCommand \index{sdcpp (preprocessor)}
4819 \labelwidthstring 00.00.0000
4824 \begin_inset LatexCommand \index{-I<path>}
4830 The additional location where the pre processor will look for <..h> or
4831 \begin_inset Quotes eld
4835 \begin_inset Quotes erd
4840 \labelwidthstring 00.00.0000
4845 \begin_inset LatexCommand \index{-D<macro[=value]>}
4851 Command line definition of macros.
4852 Passed to the preprocessor.
4854 \labelwidthstring 00.00.0000
4859 \begin_inset LatexCommand \index{-M}
4865 Tell the preprocessor to output a rule suitable for make describing the
4866 dependencies of each object file.
4867 For each source file, the preprocessor outputs one make-rule whose target
4868 is the object file name for that source file and whose dependencies are
4869 all the files `#include'd in it.
4870 This rule may be a single line or may be continued with `
4872 '-newline if it is long.
4873 The list of rules is printed on standard output instead of the preprocessed
4876 \begin_inset LatexCommand \index{-E}
4882 \labelwidthstring 00.00.0000
4887 \begin_inset LatexCommand \index{-C}
4893 Tell the preprocessor not to discard comments.
4894 Used with the `-E' option.
4896 \labelwidthstring 00.00.0000
4901 \begin_inset LatexCommand \index{-MM}
4912 Like `-M' but the output mentions only the user header files included with
4914 \begin_inset Quotes eld
4918 System header files included with `#include <file>' are omitted.
4920 \labelwidthstring 00.00.0000
4925 \begin_inset LatexCommand \index{-Aquestion(answer)}
4931 Assert the answer answer for question, in case it is tested with a preprocessor
4932 conditional such as `#if #question(answer)'.
4933 `-A-' disables the standard assertions that normally describe the target
4936 \labelwidthstring 00.00.0000
4941 \begin_inset LatexCommand \index{-Umacro}
4947 Undefine macro macro.
4948 `-U' options are evaluated after all `-D' options, but before any `-include'
4949 and `-imacros' options.
4951 \labelwidthstring 00.00.0000
4956 \begin_inset LatexCommand \index{-dM}
4962 Tell the preprocessor to output only a list of the macro definitions that
4963 are in effect at the end of preprocessing.
4964 Used with the `-E' option.
4966 \labelwidthstring 00.00.0000
4971 \begin_inset LatexCommand \index{-dD}
4977 Tell the preprocessor to pass all macro definitions into the output, in
4978 their proper sequence in the rest of the output.
4980 \labelwidthstring 00.00.0000
4985 \begin_inset LatexCommand \index{-dN}
4996 Like `-dD' except that the macro arguments and contents are omitted.
4997 Only `#define name' is included in the output.
4999 \labelwidthstring 00.00.0000
5004 preprocessorOption[,preprocessorOption]
5007 \begin_inset LatexCommand \index{-Wp preprocessorOption[,preprocessorOption]}
5012 Pass the preprocessorOption to the preprocessor
5017 \begin_inset LatexCommand \index{sdcpp (preprocessor)}
5022 SDCC uses an adapted version of the preprocessor cpp of the GNU Compiler
5023 Collection (gcc), if you need more dedicated options please refer to the
5025 \begin_inset LatexCommand \htmlurl{http://www.gnu.org/software/gcc/onlinedocs/}
5033 \begin_inset LatexCommand \index{Options linker}
5038 \begin_inset LatexCommand \index{Linker options}
5044 \labelwidthstring 00.00.0000
5064 \begin_inset LatexCommand \index{-\/-lib-path <path>}
5069 \begin_inset LatexCommand \index{-L -\/-lib-path}
5076 <absolute path to additional libraries> This option is passed to the linkage
5077 editor's additional libraries
5078 \begin_inset LatexCommand \index{Libraries}
5083 The path name must be absolute.
5084 Additional library files may be specified in the command line.
5085 See section Compiling programs for more details.
5087 \labelwidthstring 00.00.0000
5104 \begin_inset LatexCommand \index{-\/-xram-loc <Value>}
5109 <Value> The start location of the external ram
5110 \begin_inset LatexCommand \index{xdata (mcs51, ds390 storage class)}
5114 , default value is 0.
5115 The value entered can be in Hexadecimal or Decimal format, e.g.: -
5125 -xram-loc 0x8000 or -
5137 \labelwidthstring 00.00.0000
5154 \begin_inset LatexCommand \index{-\/-code-loc <Value>}
5159 <Value> The start location of the code
5160 \begin_inset LatexCommand \index{code}
5164 segment, default value 0.
5165 Note when this option is used the interrupt vector table is also relocated
5166 to the given address.
5167 The value entered can be in Hexadecimal or Decimal format, e.g.: -
5177 -code-loc 0x8000 or -
5189 \labelwidthstring 00.00.0000
5206 \begin_inset LatexCommand \index{-\/-stack-loc <Value>}
5211 <Value> By default the stack
5212 \begin_inset LatexCommand \index{stack}
5216 is placed after the data segment.
5217 Using this option the stack can be placed anywhere in the internal memory
5219 The value entered can be in Hexadecimal or Decimal format, e.g.
5230 -stack-loc 0x20 or -
5241 Since the sp register is incremented before a push or call, the initial
5242 sp will be set to one byte prior the provided value.
5243 The provided value should not overlap any other memory areas such as used
5244 register banks or the data segment and with enough space for the current
5247 \labelwidthstring 00.00.0000
5264 \begin_inset LatexCommand \index{-\/-data-loc <Value>}
5269 <Value> The start location of the internal ram data
5270 \begin_inset LatexCommand \index{data (mcs51, ds390 storage class)}
5275 The value entered can be in Hexadecimal or Decimal format, eg.
5297 (By default, the start location of the internal ram data segment is set
5298 as low as possible in memory, taking into account the used register banks
5299 and the bit segment at address 0x20.
5300 For example if register banks 0 and 1 are used without bit variables, the
5301 data segment will be set, if -
5311 -data-loc is not used, to location 0x10.)
5313 \labelwidthstring 00.00.0000
5330 \begin_inset LatexCommand \index{-\/-idata-loc <Value>}
5335 <Value> The start location of the indirectly addressable internal ram
5336 \begin_inset LatexCommand \index{idata (mcs51, ds390 storage class)}
5340 of the 8051, default value is 0x80.
5341 The value entered can be in Hexadecimal or Decimal format, eg.
5352 -idata-loc 0x88 or -
5364 \labelwidthstring 00.00.0000
5381 <Value> The start location of the bit
5382 \begin_inset LatexCommand \index{bit}
5386 addressable internal ram of the 8051.
5392 Instead an option can be passed directly to the linker: -Wl\SpecialChar ~
5395 \labelwidthstring 00.00.0000
5410 \begin_inset LatexCommand \index{-\/-out-fmt-ihx}
5419 The linker output (final object code) is in Intel Hex format.
5420 \begin_inset LatexCommand \index{Intel hex format}
5424 This is the default option.
5425 The format itself is documented in the documentation of srecord
5426 \begin_inset LatexCommand \index{srecord (tool)}
5432 \labelwidthstring 00.00.0000
5447 \begin_inset LatexCommand \index{-\/-out-fmt-s19}
5456 The linker output (final object code) is in Motorola S19 format
5457 \begin_inset LatexCommand \index{Motorola S19 format}
5462 The format itself is documented in the documentation of srecord.
5464 \labelwidthstring 00.00.0000
5469 linkOption[,linkOption]
5472 \begin_inset LatexCommand \index{-Wl linkOption[,linkOption]}
5477 Pass the linkOption to the linker.
5478 See file sdcc/as/doc/asxhtm.html for more on linker options.
5482 \begin_inset LatexCommand \index{Options MCS51}
5487 \begin_inset LatexCommand \index{MCS51 options}
5493 \labelwidthstring 00.00.0000
5508 \begin_inset LatexCommand \index{-\/-model-small}
5519 Generate code for Small Model programs, see section Memory Models for more
5521 This is the default model.
5523 \labelwidthstring 00.00.0000
5538 \begin_inset LatexCommand \index{-\/-model-large}
5544 Generate code for Large model programs, see section Memory Models for more
5546 If this option is used all source files in the project have to be compiled
5549 \labelwidthstring 00.00.0000
5564 \begin_inset LatexCommand \index{-\/-xstack}
5570 Uses a pseudo stack in the first 256 bytes in the external ram for allocating
5571 variables and passing parameters.
5573 \begin_inset LatexCommand \ref{sub:External-Stack}
5578 External Stack for more details.
5580 \labelwidthstring 00.00.0000
5598 \begin_inset LatexCommand \index{-\/-iram-size <Value>}
5602 Causes the linker to check if the internal ram usage is within limits of
5605 \labelwidthstring 00.00.0000
5623 \begin_inset LatexCommand \index{-\/-xram-size <Value>}
5627 Causes the linker to check if the external ram usage is within limits of
5630 \labelwidthstring 00.00.0000
5648 \begin_inset LatexCommand \index{-\/-code-size <Value>}
5652 Causes the linker to check if the code memory usage is within limits of
5656 DS390 / DS400 Options
5657 \begin_inset LatexCommand \index{Options DS390}
5662 \begin_inset LatexCommand \index{DS390 options}
5668 \labelwidthstring 00.00.0000
5685 \begin_inset LatexCommand \index{-\/-model-flat24}
5695 Generate 24-bit flat mode code.
5696 This is the one and only that the ds390 code generator supports right now
5697 and is default when using
5702 See section Memory Models for more details.
5704 \labelwidthstring 00.00.0000
5719 \begin_inset LatexCommand \index{-\/-protect-sp-update}
5725 disable interrupts during ESP:SP updates.
5727 \labelwidthstring 00.00.0000
5744 \begin_inset LatexCommand \index{-\/-stack-10bit}
5748 Generate code for the 10 bit stack mode of the Dallas DS80C390 part.
5749 This is the one and only that the ds390 code generator supports right now
5750 and is default when using
5755 In this mode, the stack is located in the lower 1K of the internal RAM,
5756 which is mapped to 0x400000.
5757 Note that the support is incomplete, since it still uses a single byte
5758 as the stack pointer.
5759 This means that only the lower 256 bytes of the potential 1K stack space
5760 will actually be used.
5761 However, this does allow you to reclaim the precious 256 bytes of low RAM
5762 for use for the DATA and IDATA segments.
5763 The compiler will not generate any code to put the processor into 10 bit
5765 It is important to ensure that the processor is in this mode before calling
5766 any re-entrant functions compiled with this option.
5767 In principle, this should work with the
5780 \begin_inset LatexCommand \index{-\/-stack-auto}
5786 option, but that has not been tested.
5787 It is incompatible with the
5800 \begin_inset LatexCommand \index{-\/-xstack}
5807 It also only makes sense if the processor is in 24 bit contiguous addressing
5820 -model-flat24 option
5824 \labelwidthstring 00.00.0000
5839 \begin_inset LatexCommand \index{-\/-stack-probe}
5845 insert call to function __stack_probe at each function prologue.
5847 \labelwidthstring 00.00.0000
5862 \begin_inset LatexCommand \index{-\/-tini-libid}
5868 <nnnn> LibraryID used in -mTININative.
5871 \labelwidthstring 00.00.0000
5886 \begin_inset LatexCommand \index{-\/-use-accelerator}
5892 generate code for DS390 Arithmetic Accelerator.
5897 \begin_inset LatexCommand \index{Options PIC}
5902 \begin_inset LatexCommand \index{PIC options}
5908 \labelwidthstring 00.00.0000
5923 \begin_inset LatexCommand \index{-\/-gen-banksel}
5929 enable the generation of banksel assembler directives in the PIC16
5930 \begin_inset LatexCommand \index{PIC16}
5938 \begin_inset LatexCommand \index{Options Z80}
5943 \begin_inset LatexCommand \index{Z80 options}
5949 \labelwidthstring 00.00.0000
5966 \begin_inset LatexCommand \index{-\/-callee-saves-bc}
5976 Force a called function to always save BC.
5978 \labelwidthstring 00.00.0000
5995 \begin_inset LatexCommand \index{-\/-no-std-crt0}
5999 When linking, skip the standard crt0.o object file.
6000 You must provide your own crt0.o for your system when linking.
6004 Optimization Options
6005 \begin_inset LatexCommand \index{Options optimization}
6010 \begin_inset LatexCommand \index{Optimization options}
6016 \labelwidthstring 00.00.0000
6031 \begin_inset LatexCommand \index{-\/-nogcse}
6037 Will not do global subexpression elimination, this option may be used when
6038 the compiler creates undesirably large stack/data spaces to store compiler
6040 A warning message will be generated when this happens and the compiler
6041 will indicate the number of extra bytes it allocated.
6042 It is recommended that this option NOT be used, #pragma\SpecialChar ~
6044 \begin_inset LatexCommand \index{\#pragma nogcse}
6048 can be used to turn off global subexpression elimination
6049 \begin_inset LatexCommand \index{Subexpression elimination}
6053 for a given function only.
6055 \labelwidthstring 00.00.0000
6070 \begin_inset LatexCommand \index{-\/-noinvariant}
6076 Will not do loop invariant optimizations, this may be turned off for reasons
6077 explained for the previous option.
6078 For more details of loop optimizations performed see section Loop Invariants.
6079 It is recommended that this option NOT be used, #pragma\SpecialChar ~
6081 \begin_inset LatexCommand \index{\#pragma noinvariant}
6085 can be used to turn off invariant optimizations for a given function only.
6087 \labelwidthstring 00.00.0000
6102 \begin_inset LatexCommand \index{-\/-noinduction}
6108 Will not do loop induction optimizations, see section strength reduction
6110 It is recommended that this option is NOT used, #pragma\SpecialChar ~
6112 \begin_inset LatexCommand \index{\#pragma noinduction}
6116 can be used to turn off induction optimizations for a given function only.
6118 \labelwidthstring 00.00.0000
6133 \begin_inset LatexCommand \index{-\/-nojtbound}
6144 Will not generate boundary condition check when switch statements
6145 \begin_inset LatexCommand \index{switch statement}
6149 are implemented using jump-tables.
6151 \begin_inset LatexCommand \ref{sub:'switch'-Statements}
6156 Switch Statements for more details.
6157 It is recommended that this option is NOT used, #pragma\SpecialChar ~
6159 \begin_inset LatexCommand \index{\#pragma nojtbound}
6163 can be used to turn off boundary checking for jump tables for a given function
6166 \labelwidthstring 00.00.0000
6181 \begin_inset LatexCommand \index{-\/-noloopreverse}
6190 Will not do loop reversal
6191 \begin_inset LatexCommand \index{Loop reversing}
6197 \labelwidthstring 00.00.0000
6214 \begin_inset LatexCommand \index{-\/-nolabelopt }
6218 Will not optimize labels (makes the dumpfiles more readable).
6220 \labelwidthstring 00.00.0000
6235 \begin_inset LatexCommand \index{-\/-no-xinit-opt}
6241 Will not memcpy initialized data from code space into xdata space.
6242 This saves a few bytes in code space if you don't have initialized data.
6244 \labelwidthstring 00.00.0000
6259 \begin_inset LatexCommand \index{-\/-nooverlay}
6265 The compiler will not overlay parameters and local variables of any function,
6266 see section Parameters and local variables for more details.
6268 \labelwidthstring 00.00.0000
6283 \begin_inset LatexCommand \index{-\/-no-peep}
6289 Disable peep-hole optimization.
6291 \labelwidthstring 00.00.0000
6308 \begin_inset LatexCommand \index{-\/-peep-file}
6313 <filename> This option can be used to use additional rules to be used by
6314 the peep hole optimizer.
6316 \begin_inset LatexCommand \ref{sub:Peephole-Optimizer}
6321 Peep Hole optimizations for details on how to write these rules.
6323 \labelwidthstring 00.00.0000
6338 \begin_inset LatexCommand \index{-\/-peep-asm}
6344 Pass the inline assembler code through the peep hole optimizer.
6345 This can cause unexpected changes to inline assembler code, please go through
6346 the peephole optimizer
6347 \begin_inset LatexCommand \index{Peephole optimizer}
6351 rules defined in the source file tree '<target>/peeph.def' before using
6356 \begin_inset LatexCommand \index{Options other}
6362 \labelwidthstring 00.00.0000
6378 \begin_inset LatexCommand \index{-\/-compile-only}
6383 \begin_inset LatexCommand \index{-c -\/-compile-only}
6389 will compile and assemble the source, but will not call the linkage editor.
6391 \labelwidthstring 00.00.0000
6410 \begin_inset LatexCommand \index{-\/-c1mode}
6416 reads the preprocessed source from standard input and compiles it.
6417 The file name for the assembler output must be specified using the -o option.
6419 \labelwidthstring 00.00.0000
6424 \begin_inset LatexCommand \index{-E}
6430 Run only the C preprocessor.
6431 Preprocess all the C source files specified and output the results to standard
6434 \labelwidthstring 00.00.0000
6440 \begin_inset LatexCommand \index{-o <path/file>}
6446 The output path resp.
6447 file where everything will be placed.
6448 If the parameter is a path, it must have a trailing slash (or backslash
6449 for the Windows binaries) to be recognized as a path.
6452 \labelwidthstring 00.00.0000
6467 \begin_inset LatexCommand \index{-\/-stack-auto}
6478 All functions in the source file will be compiled as
6483 \begin_inset LatexCommand \index{reentrant}
6488 the parameters and local variables will be allocated on the stack
6489 \begin_inset LatexCommand \index{stack}
6494 see section Parameters and Local Variables for more details.
6495 If this option is used all source files in the project should be compiled
6499 \labelwidthstring 00.00.0000
6514 \begin_inset LatexCommand \index{-\/-callee-saves}
6518 function1[,function2][,function3]....
6521 The compiler by default uses a caller saves convention for register saving
6522 across function calls, however this can cause unnecessary register pushing
6523 & popping when calling small functions from larger functions.
6524 This option can be used to switch the register saving convention for the
6525 function names specified.
6526 The compiler will not save registers when calling these functions, no extra
6527 code will be generated at the entry & exit (function prologue
6530 \begin_inset LatexCommand \index{function prologue}
6539 \begin_inset LatexCommand \index{function epilogue}
6545 ) for these functions to save & restore the registers used by these functions,
6546 this can SUBSTANTIALLY reduce code & improve run time performance of the
6548 In the future the compiler (with inter procedural analysis) will be able
6549 to determine the appropriate scheme to use for each function call.
6550 DO NOT use this option for built-in functions such as _mulint..., if this
6551 option is used for a library function the appropriate library function
6552 needs to be recompiled with the same option.
6553 If the project consists of multiple source files then all the source file
6554 should be compiled with the same -
6564 -callee-saves option string.
6565 Also see #pragma\SpecialChar ~
6567 \begin_inset LatexCommand \index{\#pragma callee\_saves}
6573 \labelwidthstring 00.00.0000
6588 \begin_inset LatexCommand \index{-\/-debug}
6597 When this option is used the compiler will generate debug information.
6598 The debug information collected in a file with .cdb extension can be used
6600 For more information see documentation for SDCDB.
6601 Another file with no extension contains debug information in AOMF or AOMF51
6602 \begin_inset LatexCommand \index{AOMF, AOMF51}
6606 format which is commonly used by third party tools.
6608 \labelwidthstring 00.00.0000
6613 \begin_inset LatexCommand \index{-S}
6624 Stop after the stage of compilation proper; do not assemble.
6625 The output is an assembler code file for the input file specified.
6627 \labelwidthstring 00.00.0000
6642 \begin_inset LatexCommand \index{-\/-int-long-reent}
6648 Integer (16 bit) and long (32 bit) libraries have been compiled as reentrant.
6649 Note by default these libraries are compiled as non-reentrant.
6650 See section Installation for more details.
6652 \labelwidthstring 00.00.0000
6667 \begin_inset LatexCommand \index{-\/-cyclomatic}
6676 This option will cause the compiler to generate an information message for
6677 each function in the source file.
6678 The message contains some
6682 information about the function.
6683 The number of edges and nodes the compiler detected in the control flow
6684 graph of the function, and most importantly the
6686 cyclomatic complexity
6687 \begin_inset LatexCommand \index{Cyclomatic complexity}
6693 see section on Cyclomatic Complexity for more details.
6695 \labelwidthstring 00.00.0000
6710 \begin_inset LatexCommand \index{-\/-float-reent}
6716 Floating point library is compiled as reentrant
6717 \begin_inset LatexCommand \index{reentrant}
6722 See section Installation for more details.
6724 \labelwidthstring 00.00.0000
6739 \begin_inset LatexCommand \index{-\/-main-return}
6745 This option can be used when the code generated is called by a monitor
6747 The compiler will generate a 'ret' upon return from the 'main'
6748 \begin_inset LatexCommand \index{main return}
6753 The default setting is to lock up i.e.
6760 \labelwidthstring 00.00.0000
6775 \begin_inset LatexCommand \index{-\/-nostdincl}
6781 This will prevent the compiler from passing on the default include path
6782 to the preprocessor.
6784 \labelwidthstring 00.00.0000
6799 \begin_inset LatexCommand \index{-\/-nostdlib}
6805 This will prevent the compiler from passing on the default library
6806 \begin_inset LatexCommand \index{Libraries}
6812 \labelwidthstring 00.00.0000
6827 \begin_inset LatexCommand \index{-\/-verbose}
6833 Shows the various actions the compiler is performing.
6835 \labelwidthstring 00.00.0000
6840 \begin_inset LatexCommand \index{-V}
6846 Shows the actual commands the compiler is executing.
6848 \labelwidthstring 00.00.0000
6863 \begin_inset LatexCommand \index{-\/-no-c-code-in-asm}
6869 Hides your ugly and inefficient c-code from the asm file, so you can always
6870 blame the compiler :).
6872 \labelwidthstring 00.00.0000
6887 \begin_inset LatexCommand \index{-\/-i-code-in-asm}
6893 Include i-codes in the asm file.
6894 Sounds like noise but is most helpful for debugging the compiler itself.
6896 \labelwidthstring 00.00.0000
6911 \begin_inset LatexCommand \index{-\/-less-pedantic}
6917 Disable some of the more pedantic warnings
6918 \begin_inset LatexCommand \index{Warnings}
6922 (jwk burps: please be more specific here, please!).
6923 If you want rather more than less warnings you should consider using a
6924 separate tool dedicated to syntax checking like splint
6925 \begin_inset LatexCommand \url{www.splint.org}
6931 \labelwidthstring 00.00.0000
6946 \begin_inset LatexCommand \index{-\/-print-search-dirs}
6952 Display the directories in the compiler's search path
6954 \labelwidthstring 00.00.0000
6969 \begin_inset LatexCommand \index{-\/-vc}
6975 Display errors and warnings using MSVC style, so you can use SDCC with
6978 \labelwidthstring 00.00.0000
6993 \begin_inset LatexCommand \index{-\/-use-stdout}
6999 Send errors and warnings to stdout instead of stderr.
7001 \labelwidthstring 00.00.0000
7006 asmOption[,asmOption]
7009 \begin_inset LatexCommand \index{-Wa asmOption[,asmOption]}
7014 Pass the asmOption to the assembler
7015 \begin_inset LatexCommand \index{Options assembler}
7020 \begin_inset LatexCommand \index{Assembler options}
7025 See file sdcc/as/doc/asxhtm.html for assembler options.
7028 Intermediate Dump Options
7029 \begin_inset LatexCommand \label{sub:Intermediate-Dump-Options}
7034 \begin_inset LatexCommand \index{Options intermediate dump}
7039 \begin_inset LatexCommand \index{Intermediate dump options}
7046 The following options are provided for the purpose of retargetting and debugging
7048 These provided a means to dump the intermediate code (iCode
7049 \begin_inset LatexCommand \index{iCode}
7053 ) generated by the compiler in human readable form at various stages of
7054 the compilation process.
7055 More on iCodes see chapter
7056 \begin_inset LatexCommand \ref{sub:The-anatomy-of}
7061 \begin_inset Quotes srd
7064 The anatomy of the compiler
7065 \begin_inset Quotes srd
7070 \labelwidthstring 00.00.0000
7085 \begin_inset LatexCommand \index{-\/-dumpraw}
7091 This option will cause the compiler to dump the intermediate code into
7094 <source filename>.dumpraw
7096 just after the intermediate code has been generated for a function, i.e.
7097 before any optimizations are done.
7099 \begin_inset LatexCommand \index{Basic blocks}
7103 at this stage ordered in the depth first number, so they may not be in
7104 sequence of execution.
7106 \labelwidthstring 00.00.0000
7121 \begin_inset LatexCommand \index{-\/-dumpgcse}
7127 Will create a dump of iCode's, after global subexpression elimination
7128 \begin_inset LatexCommand \index{Global subexpression elimination}
7134 <source filename>.dumpgcse.
7136 \labelwidthstring 00.00.0000
7151 \begin_inset LatexCommand \index{-\/-dumpdeadcode}
7157 Will create a dump of iCode's, after deadcode elimination
7158 \begin_inset LatexCommand \index{Dead-code elimination}
7164 <source filename>.dumpdeadcode.
7166 \labelwidthstring 00.00.0000
7181 \begin_inset LatexCommand \index{-\/-dumploop}
7190 Will create a dump of iCode's, after loop optimizations
7191 \begin_inset LatexCommand \index{Loop optimization}
7197 <source filename>.dumploop.
7199 \labelwidthstring 00.00.0000
7214 \begin_inset LatexCommand \index{-\/-dumprange}
7223 Will create a dump of iCode's, after live range analysis
7224 \begin_inset LatexCommand \index{Live range analysis}
7230 <source filename>.dumprange.
7232 \labelwidthstring 00.00.0000
7247 \begin_inset LatexCommand \index{-\/-dumlrange}
7253 Will dump the life ranges
7254 \begin_inset LatexCommand \index{Live range analysis}
7260 \labelwidthstring 00.00.0000
7275 \begin_inset LatexCommand \index{-\/-dumpregassign}
7284 Will create a dump of iCode's, after register assignment
7285 \begin_inset LatexCommand \index{Register assignment}
7291 <source filename>.dumprassgn.
7293 \labelwidthstring 00.00.0000
7308 \begin_inset LatexCommand \index{-\/-dumplrange}
7314 Will create a dump of the live ranges of iTemp's
7316 \labelwidthstring 00.00.0000
7331 \begin_inset LatexCommand \index{-\/-dumpall}
7342 Will cause all the above mentioned dumps to be created.
7345 Redirecting output on Windows Shells
7348 By default SDCC writes it's error messages to
7349 \begin_inset Quotes sld
7353 \begin_inset Quotes srd
7357 To force all messages to
7358 \begin_inset Quotes sld
7362 \begin_inset Quotes srd
7386 \begin_inset LatexCommand \index{-\/-use-stdout}
7391 Additionally, if you happen to have visual studio installed in your windows
7392 machine, you can use it to compile your sources using a custom build and
7408 \begin_inset LatexCommand \index{-\/-vc}
7413 Something like this should work:
7457 -model-large -c $(InputPath)
7460 Environment variables
7461 \begin_inset LatexCommand \index{Environment variables}
7468 SDCC recognizes the following environment variables:
7470 \labelwidthstring 00.00.0000
7475 \begin_inset LatexCommand \index{SDCC\_LEAVE\_SIGNALS}
7481 SDCC installs a signal handler
7482 \begin_inset LatexCommand \index{signal handler}
7486 to be able to delete temporary files after an user break (^C) or an exception.
7487 If this environment variable is set, SDCC won't install the signal handler
7488 in order to be able to debug SDCC.
7490 \labelwidthstring 00.00.0000
7497 \begin_inset LatexCommand \index{TMP, TEMP, TMPDIR}
7503 Path, where temporary files will be created.
7504 The order of the variables is the search order.
7505 In a standard *nix environment these variables are not set, and there's
7506 no need to set them.
7507 On Windows it's recommended to set one of them.
7509 \labelwidthstring 00.00.0000
7514 \begin_inset LatexCommand \index{SDCC\_HOME}
7521 \begin_inset LatexCommand \ref{sub:Install-paths}
7527 \begin_inset Quotes sld
7531 \begin_inset Quotes srd
7536 \labelwidthstring 00.00.0000
7541 \begin_inset LatexCommand \index{SDCC\_INCLUDE}
7548 \begin_inset LatexCommand \ref{sub:Search-Paths}
7554 \begin_inset Quotes sld
7558 \begin_inset Quotes srd
7563 \labelwidthstring 00.00.0000
7568 \begin_inset LatexCommand \index{SDCC\_LIB}
7575 \begin_inset LatexCommand \ref{sub:Search-Paths}
7581 \begin_inset Quotes sld
7585 \begin_inset Quotes srd
7591 There are some more environment variables recognized by SDCC, but these
7592 are solely used for debugging purposes.
7593 They can change or disappear very quickly, and will never be documented.
7596 Storage Class Language Extensions
7599 MCS51/DS390 Storage Class
7600 \begin_inset LatexCommand \index{Storage class}
7607 In addition to the ANSI storage classes SDCC allows the following MCS51
7608 specific storage classes:
7609 \layout Subsubsection
7612 \begin_inset LatexCommand \index{data (mcs51, ds390 storage class)}
7617 \begin_inset LatexCommand \index{near (storage class)}
7628 storage class for the Small Memory model (
7636 can be used synonymously).
7637 Variables declared with this storage class will be allocated in the directly
7638 addressable portion of the internal RAM of a 8051, e.g.:
7643 data unsigned char test_data;
7646 Writing 0x01 to this variable generates the assembly code:
7651 75*00 01\SpecialChar ~
7657 \layout Subsubsection
7660 \begin_inset LatexCommand \index{xdata (mcs51, ds390 storage class)}
7665 \begin_inset LatexCommand \index{far (storage class)}
7672 Variables declared with this storage class will be placed in the external
7678 storage class for the Large Memory model, e.g.:
7683 xdata unsigned char test_xdata;
7686 Writing 0x01 to this variable generates the assembly code:
7691 90s00r00\SpecialChar ~
7720 \layout Subsubsection
7723 \begin_inset LatexCommand \index{idata (mcs51, ds390 storage class)}
7730 Variables declared with this storage class will be allocated into the indirectly
7731 addressable portion of the internal ram of a 8051, e.g.:
7736 idata unsigned char test_idata;
7739 Writing 0x01 to this variable generates the assembly code:
7768 Please note, the first 128 byte of idata physically access the same RAM
7770 The original 8051 had 128 byte idata memory, nowadays most devices have
7771 256 byte idata memory.
7773 \begin_inset LatexCommand \index{stack}
7777 is located in idata memory.
7778 \layout Subsubsection
7781 \begin_inset LatexCommand \index{pdata (mcs51, ds390 storage class)}
7788 Paged xdata access is currently not as straightforward as using the other
7789 addressing modes of a 8051.
7790 The following example writes 0x01 to the address pointed to.
7791 Please note, pdata access physically accesses xdata memory.
7792 The high byte of the address is determined by port P2
7793 \begin_inset LatexCommand \index{P2 (mcs51 sfr)}
7797 (or in case of some 8051 variants by a separate Special Function Register,
7799 \begin_inset LatexCommand \ref{sub:MCS51-variants}
7808 pdata unsigned char *test_pdata_ptr;
7820 test_pdata_ptr = (pdata *)0xfe;
7826 *test_pdata_ptr = 1;
7831 Generates the assembly code:
7836 75*01 FE\SpecialChar ~
7840 _test_pdata_ptr,#0xFE
7872 Be extremely carefull if you use pdata together with the -
7883 \begin_inset LatexCommand \index{-\/-xstack}
7888 \layout Subsubsection
7891 \begin_inset LatexCommand \index{code}
7898 'Variables' declared with this storage class will be placed in the code
7904 code unsigned char test_code;
7907 Read access to this variable generates the assembly code:
7912 90s00r6F\SpecialChar ~
7915 mov dptr,#_test_code
7944 indexed arrays of characters in code memory can be accessed efficiently:
7949 code char test_array[] = {'c','h','e','a','p'};
7952 Read access to this array using an 8-bit unsigned index generates the assembly
7969 90s00r41\SpecialChar ~
7972 mov dptr,#_test_array
7987 \layout Subsubsection
7990 \begin_inset LatexCommand \index{bit}
7997 This is a data-type and a storage class specifier.
7998 When a variable is declared as a bit, it is allocated into the bit addressable
7999 memory of 8051, e.g.:
8007 Writing 1 to this variable generates the assembly code:
8023 The bit addressable memory consists of 128 bits which are located from 0x20
8024 to 0x2f in data memory.
8028 Apart from this 8051 specific storage class most architectures support ANSI-C
8030 \begin_inset LatexCommand \index{bitfields}
8040 Not really meant as examples, but nevertheless showing what bitfields are
8041 about: device/include/mc68hc908qy.h and support/regression/tests/bitfields.c
8045 \layout Subsubsection
8048 \begin_inset LatexCommand \index{sfr}
8053 \begin_inset LatexCommand \index{sbit}
8060 Like the bit keyword,
8064 signifies both a data-type and storage class, they are used to describe
8085 variables of a 8051, eg:
8091 \begin_inset LatexCommand \index{at}
8095 0x80 P0;\SpecialChar ~
8096 /* special function register P0 at location 0x80 */
8098 sbit at 0xd7 CY; /* CY (Carry Flag
8099 \begin_inset LatexCommand \index{Flags}
8104 \begin_inset LatexCommand \index{Carry flag}
8111 Special function registers which are located on an address dividable by
8112 8 are bit-addressable, an
8116 addresses a specific bit within these sfr.
8117 \layout Subsubsection
8120 \begin_inset LatexCommand \index{Pointer}
8124 to MCS51/DS390 specific memory spaces
8127 SDCC allows (via language extensions) pointers to explicitly point to any
8128 of the memory spaces
8129 \begin_inset LatexCommand \index{Memory model}
8134 In addition to the explicit pointers, the compiler uses (by default) generic
8135 pointers which can be used to point to any of the memory spaces.
8139 Pointer declaration examples:
8144 /* pointer physically in internal ram pointing to object in external ram
8147 xdata unsigned char * data p;
8151 /* pointer physically in external ram pointing to object in internal ram
8154 data unsigned char * xdata p;
8158 /* pointer physically in code rom pointing to data in xdata space */
8160 xdata unsigned char * code p;
8164 /* pointer physically in code space pointing to data in code space */
8166 code unsigned char * code p;
8170 /* the following is a generic pointer physically located in xdata space
8176 Well you get the idea.
8181 All unqualified pointers are treated as 3-byte (4-byte for the ds390)
8194 The highest order byte of the
8198 pointers contains the data space information.
8199 Assembler support routines are called whenever data is stored or retrieved
8205 These are useful for developing reusable library
8206 \begin_inset LatexCommand \index{Libraries}
8211 Explicitly specifying the pointer type will generate the most efficient
8213 \layout Subsubsection
8215 Notes on MCS51 memory
8216 \begin_inset LatexCommand \index{MCS51 memory}
8223 The 8051 family of microcontrollers have a minimum of 128 bytes of internal
8224 RAM memory which is structured as follows:
8228 - Bytes 00-1F - 32 bytes to hold up to 4 banks of the registers R0 to R7,
8231 - Bytes 20-2F - 16 bytes to hold 128 bit
8232 \begin_inset LatexCommand \index{bit}
8238 - Bytes 30-7F - 80 bytes for general purpose use.
8243 Additionally some members of the MCS51 family may have up to 128 bytes of
8244 additional, indirectly addressable, internal RAM memory (
8249 \begin_inset LatexCommand \index{idata (mcs51, ds390 storage class)}
8254 Furthermore, some chips may have some built in external memory (
8259 \begin_inset LatexCommand \index{xdata (mcs51, ds390 storage class)}
8263 ) which should not be confused with the internal, directly addressable RAM
8269 \begin_inset LatexCommand \index{data (mcs51, ds390 storage class)}
8274 Sometimes this built in
8278 memory has to be activated before using it (you can probably find this
8279 information on the datasheet of the microcontroller your are using, see
8281 \begin_inset LatexCommand \ref{sub:Startup-Code}
8289 Normally SDCC will only use the first bank
8290 \begin_inset LatexCommand \index{register bank (mcs51, ds390)}
8294 of registers (register bank 0), but it is possible to specify that other
8295 banks of registers should be used in interrupt
8296 \begin_inset LatexCommand \index{interrupt}
8301 By default, the compiler will place the stack after the last byte of allocated
8302 memory for variables.
8303 For example, if the first 2 banks of registers are used, and only four
8308 variables, it will position the base of the internal stack at address 20
8310 This implies that as the stack
8311 \begin_inset LatexCommand \index{stack}
8315 grows, it will use up the remaining register banks, and the 16 bytes used
8316 by the 128 bit variables, and 80 bytes for general purpose use.
8317 If any bit variables are used, the data variables will be placed after
8318 the byte holding the last bit variable.
8319 For example, if register banks 0 and 1 are used, and there are 9 bit variables
8324 variables will be placed starting at address 0x22.
8336 \begin_inset LatexCommand \index{-\/-data-loc<Value>}
8340 to specify the start address of the
8354 -iram-size to specify the size of the total internal RAM (
8366 By default the 8051 linker will place the stack after the last byte of data
8379 \begin_inset LatexCommand \index{-\/-stack-loc<Value>}
8383 allows you to specify the start of the stack, i.e.
8384 you could start it after any data in the general purpose area.
8385 If your microcontroller has additional indirectly addressable internal
8390 ) you can place the stack on it.
8391 You may also need to use -
8402 \begin_inset LatexCommand \index{-\/-xdata-loc<Value>}
8406 to set the start address of the external RAM (
8421 \begin_inset LatexCommand \index{-\/-data-loc}
8425 to specify its size.
8426 Same goes for the code memory, using -
8437 \begin_inset LatexCommand \index{-\/-data-loc}
8452 \begin_inset LatexCommand \index{-\/-data-loc}
8457 If in doubt, don't specify any options and see if the resulting memory
8458 layout is appropriate, then you can adjust it.
8461 The linker generates two files with memory allocation information.
8462 The first, with extension .map
8463 \begin_inset LatexCommand \index{<file>.map}
8467 shows all the variables and segments.
8468 The second with extension .mem
8469 \begin_inset LatexCommand \index{<file>.mem}
8473 shows the final memory layout.
8474 The linker will complain either if memory segments overlap, there is not
8475 enough memory, or there is not enough space for stack.
8476 If you get any linking warnings and/or errors related to stack or segments
8477 allocation, take a look at either the .map or .mem files to find out what
8479 The .mem file may even suggest a solution to the problem.
8482 Z80/Z180 Storage Class
8483 \begin_inset LatexCommand \index{Storage class}
8488 \layout Subsubsection
8491 \begin_inset LatexCommand \index{sfr}
8495 (in/out to 8-bit addresses)
8499 \begin_inset LatexCommand \index{Z80}
8503 family has separate address spaces for memory and
8513 \begin_inset LatexCommand \index{I/O memory (Z80, Z180)}
8517 is accessed with special instructions, e.g.:
8522 sfr at 0x78 IoPort;\SpecialChar ~
8524 /* define a var in I/O space at 78h called IoPort */
8528 Writing 0x01 to this variable generates the assembly code:
8548 \layout Subsubsection
8551 \begin_inset LatexCommand \index{sfr}
8555 (in/out to 16-bit addresses)
8562 is used to support 16 bit addresses in I/O memory e.g.:
8568 \begin_inset LatexCommand \index{at}
8575 Writing 0x01 to this variable generates the assembly code:
8580 01 23 01\SpecialChar ~
8600 \layout Subsubsection
8603 \begin_inset LatexCommand \index{sfr}
8607 (in0/out0 to 8 bit addresses on Z180
8608 \begin_inset LatexCommand \index{Z180}
8613 \begin_inset LatexCommand \index{HD64180}
8620 The compiler option -
8630 -portmode=180 (80) and a compiler #pragma\SpecialChar ~
8632 \begin_inset LatexCommand \index{\#pragma portmode}
8636 =z180 (z80) is used to turn on (off) the Z180/HD64180 port addressing instructio
8646 If you include the file z180.h this will be set automatically.
8650 \begin_inset LatexCommand \index{Absolute addressing}
8657 Data items can be assigned an absolute address with the
8660 \begin_inset LatexCommand \index{at}
8666 keyword, in addition to a storage class, e.g.:
8672 \begin_inset LatexCommand \index{xdata (mcs51, ds390 storage class)}
8677 \begin_inset LatexCommand \index{at}
8681 0x7ffe unsigned int chksum;
8684 In the above example the variable chksum will located at 0x7ffe and 0x7fff
8685 of the external ram.
8690 reserve any space for variables declared in this way (they are implemented
8691 with an equate in the assembler).
8692 Thus it is left to the programmer to make sure there are no overlaps with
8693 other variables that are declared without the absolute address.
8694 The assembler listing file (.lst
8695 \begin_inset LatexCommand \index{<file>.lst}
8699 ) and the linker output files (.rst
8700 \begin_inset LatexCommand \index{<file>.rst}
8705 \begin_inset LatexCommand \index{<file>.map}
8709 ) are good places to look for such overlaps.
8710 Variables with an absolute address are
8715 \begin_inset LatexCommand \index{Variable initialization}
8722 In case of memory mapped I/O devices the keyword
8726 should be used to tell the compiler that accesses might not be optimized
8733 \begin_inset LatexCommand \index{volatile}
8738 \begin_inset LatexCommand \index{xdata (mcs51, ds390 storage class)}
8743 \begin_inset LatexCommand \index{at}
8747 0x8000 unsigned char PORTA_8255;
8750 For some architectures (mcs51) array accesses are more efficient if an (xdata/fa
8755 \begin_inset LatexCommand \index{Aligned array}
8762 starts at a block (256 byte) boundary
8763 \begin_inset LatexCommand \index{block boundary}
8768 \begin_inset LatexCommand \ref{sub:A-Step-by Assembler Introduction}
8774 Absolute addresses can be specified for variables in all storage classes,
8781 \begin_inset LatexCommand \index{bit}
8786 \begin_inset LatexCommand \index{at}
8793 The above example will allocate the variable at offset 0x02 in the bit-addressab
8795 There is no real advantage to assigning absolute addresses to variables
8796 in this manner, unless you want strict control over all the variables allocated.
8797 One possible use would be to write hardware portable code.
8798 For example, if you have a routine that uses one or more of the microcontroller
8799 I/O pins, and such pins are different for two different hardwares, you
8800 can declare the I/O pins in your routine using:
8805 extern volatile bit SDI;
8807 extern volatile bit SCLK;
8809 extern volatile bit CPOL;
8813 void DS1306_put(unsigned char value)
8821 unsigned char mask=0x80;
8845 SDI=(value & mask)?1:0;
8886 Then, someplace in the code for the first hardware you would use
8891 bit at 0x80 SDI;\SpecialChar ~
8895 /* I/O port 0, bit 0 */
8897 bit at 0x81 SCLK;\SpecialChar ~
8900 /* I/O port 0, bit 1 */
8902 bit CPOL;\SpecialChar ~
8913 /* This is a variable, let the linker allocate this one */
8916 Similarly, for the second hardware you would use
8921 bit at 0x83 SDI;\SpecialChar ~
8925 /* I/O port 0, bit 3 */
8927 bit at 0x91 SCLK;\SpecialChar ~
8930 /* I/O port 1, bit 1 */
8933 \begin_inset LatexCommand \index{bit}
8948 /* This is a variable, let the linker allocate this one */
8951 and you can use the same hardware dependent routine without changes, as
8952 for example in a library.
8953 This is somehow similar to sbit, but only one absolute address has to be
8954 specified in the whole project.
8958 \begin_inset LatexCommand \index{Parameters}
8963 \begin_inset LatexCommand \index{function parameter}
8968 \begin_inset LatexCommand \index{local variables}
8975 Automatic (local) variables and parameters to functions can either be placed
8976 on the stack or in data-space.
8977 The default action of the compiler is to place these variables in the internal
8978 RAM (for small model) or external RAM (for large model).
8979 This in fact makes them similar to
8982 \begin_inset LatexCommand \index{static}
8988 so by default functions are non-reentrant
8989 \begin_inset LatexCommand \index{reentrant}
8998 They can be placed on the stack
8999 \begin_inset LatexCommand \index{stack}
9016 \begin_inset LatexCommand \index{-\/-stack-auto}
9022 option or by using the
9025 \begin_inset LatexCommand \index{reentrant}
9031 keyword in the function declaration, e.g.:
9036 unsigned char foo(char i) reentrant
9050 Since stack space on 8051 is limited, the
9068 option should be used sparingly.
9069 Note that the reentrant keyword just means that the parameters & local
9070 variables will be allocated to the stack, it
9074 mean that the function is register bank
9075 \begin_inset LatexCommand \index{register bank (mcs51, ds390)}
9084 \begin_inset LatexCommand \index{local variables}
9088 can be assigned storage classes and absolute
9089 \begin_inset LatexCommand \index{Absolute addressing}
9106 xdata unsigned char i;
9119 \begin_inset LatexCommand \index{at}
9123 0x31 unsigned char j;
9135 In the above example the variable
9139 will be allocated in the external ram,
9143 in bit addressable space and
9162 or when a function is declared as
9166 this should only be done for static variables.
9170 \begin_inset LatexCommand \index{function parameter}
9174 however are not allowed any storage class
9175 \begin_inset LatexCommand \index{Storage class}
9179 , (storage classes for parameters will be ignored), their allocation is
9180 governed by the memory model in use, and the reentrancy options.
9184 \begin_inset LatexCommand \label{sub:Overlaying}
9189 \begin_inset LatexCommand \index{Overlaying}
9197 \begin_inset LatexCommand \index{reentrant}
9201 functions SDCC will try to reduce internal ram space usage by overlaying
9202 parameters and local variables of a function (if possible).
9203 Parameters and local variables
9204 \begin_inset LatexCommand \index{local variables}
9208 of a function will be allocated to an overlayable segment if the function
9211 no other function calls and the function is non-reentrant and the memory
9213 \begin_inset LatexCommand \index{Memory model}
9220 If an explicit storage class
9221 \begin_inset LatexCommand \index{Storage class}
9225 is specified for a local variable, it will NOT be overlayed.
9228 Note that the compiler (not the linkage editor) makes the decision for overlayin
9230 Functions that are called from an interrupt service routine should be preceded
9231 by a #pragma\SpecialChar ~
9233 \begin_inset LatexCommand \index{\#pragma nooverlay}
9237 if they are not reentrant.
9240 Also note that the compiler does not do any processing of inline assembler
9241 code, so the compiler might incorrectly assign local variables and parameters
9242 of a function into the overlay segment if the inline assembler code calls
9243 other c-functions that might use the overlay.
9244 In that case the #pragma\SpecialChar ~
9245 nooverlay should be used.
9248 Parameters and local variables of functions that contain 16 or 32 bit multiplica
9250 \begin_inset LatexCommand \index{Multiplication}
9255 \begin_inset LatexCommand \index{Division}
9259 will NOT be overlayed since these are implemented using external functions,
9268 \begin_inset LatexCommand \index{\#pragma nooverlay}
9274 void set_error(unsigned char errcd)
9290 void some_isr () interrupt
9291 \begin_inset LatexCommand \index{interrupt}
9321 In the above example the parameter
9329 would be assigned to the overlayable segment if the #pragma\SpecialChar ~
9331 not present, this could cause unpredictable runtime behavior when called
9332 from an interrupt service routine.
9333 The #pragma\SpecialChar ~
9334 nooverlay ensures that the parameters and local variables for
9335 the function are NOT overlayed.
9338 Interrupt Service Routines
9339 \begin_inset LatexCommand \label{sub:Interrupt-Service-Routines}
9358 outines to be coded in C, with some extended keywords.
9363 void timer_isr (void) interrupt 1 using 1
9377 The optional number following the
9380 \begin_inset LatexCommand \index{interrupt}
9386 keyword is the interrupt number this routine will service.
9387 When present, the compiler will insert a call to this routine in the interrupt
9388 vector table for the interrupt number specified.
9389 If you have multiple source files in your project, interrupt service routines
9390 can be present in any of them, but a prototype of the isr MUST be present
9391 or included in the file that contains the function
9400 keyword can be used to tell the compiler to use the specified register
9401 bank (8051 specific) when generating code for this function.
9407 Interrupt numbers and the corresponding address & descriptions for the Standard
9408 8051/8052 are listed below.
9409 SDCC will automatically adjust the interrupt vector table to the maximum
9410 interrupt number specified.
9416 \begin_inset Tabular
9417 <lyxtabular version="3" rows="7" columns="3">
9419 <column alignment="center" valignment="top" leftline="true" width="0in">
9420 <column alignment="center" valignment="top" leftline="true" width="0in">
9421 <column alignment="center" valignment="top" leftline="true" rightline="true" width="0in">
9422 <row topline="true" bottomline="true">
9423 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
9431 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
9439 <cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
9448 <row topline="true">
9449 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
9457 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
9465 <cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
9474 <row topline="true">
9475 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
9483 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
9491 <cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
9500 <row topline="true">
9501 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
9509 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
9517 <cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
9526 <row topline="true">
9527 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
9535 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
9543 <cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
9552 <row topline="true">
9553 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
9561 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
9569 <cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
9578 <row topline="true" bottomline="true">
9579 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
9587 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
9595 <cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
9613 If the interrupt service routine is defined without
9616 \begin_inset LatexCommand \index{using (mcs51, ds390 register bank)}
9622 a register bank or with register bank 0 (
9626 0), the compiler will save the registers used by itself on the stack upon
9627 entry and restore them at exit, however if such an interrupt service routine
9628 calls another function then the entire register bank will be saved on the
9630 This scheme may be advantageous for small interrupt service routines which
9631 have low register usage.
9634 If the interrupt service routine is defined to be using a specific register
9639 & psw are saved and restored, if such an interrupt service routine calls
9640 another function (using another register bank) then the entire register
9641 bank of the called function will be saved on the stack.
9642 This scheme is recommended for larger interrupt service routines.
9645 Interrupt service routines open the door for some very interesting bugs:
9649 If the interrupt service routines changes variables which are accessed by
9650 other functions these variables should be declared
9655 \begin_inset LatexCommand \index{volatile}
9663 If the access to these variables is not
9666 \begin_inset LatexCommand \index{atomic access}
9673 the processor needs more than one instruction for the access and could
9674 be interrupted while accessing the variable) the interrupt must disabled
9675 during the access to avoid inconsistent data.
9676 Access to 16 or 32 bit variables is obviously not atomic on 8 bit CPUs
9677 and should be protected by disabling interrupts.
9678 You're not automatically on the safe side if you use 8 bit variables though.
9679 We need an example here: f.e.
9680 on the 8051 the harmless looking
9681 \begin_inset Quotes srd
9691 \begin_inset Quotes sld
9700 \begin_inset Quotes srd
9710 \begin_inset Quotes sld
9713 from within an interrupt routine might get lost if the interrupt occurs
9716 \begin_inset Quotes sld
9721 counter\SpecialChar ~
9726 \begin_inset Quotes srd
9729 is not atomic on the 8051 even if
9733 is located in data memory.
9734 Bugs like these are hard to reproduce and can cause a lot of trouble.
9738 A special note here, int (16 bit) and long (32 bit) integer division
9739 \begin_inset LatexCommand \index{Division}
9744 \begin_inset LatexCommand \index{Multiplication}
9749 \begin_inset LatexCommand \index{Modulus}
9754 \begin_inset LatexCommand \index{Floating point support}
9758 operations are implemented using external support routines developed in
9760 If an interrupt service routine needs to do any of these operations then
9761 the support routines (as mentioned in a following section) will have to
9762 be recompiled using the
9775 \begin_inset LatexCommand \index{-\/-stack-auto}
9781 option and the source file will need to be compiled using the
9796 \begin_inset LatexCommand \index{-\/-int-long-reent}
9803 Calling other functions from an interrupt service routine is not recommended,
9804 avoid it if possible.
9805 Note that when some function is called from an interrupt service routine
9806 it should be preceded by a #pragma\SpecialChar ~
9808 \begin_inset LatexCommand \index{\#pragma nooverlay}
9812 if it is not reentrant.
9813 Furthermore nonreentrant functions should not be called from the main program
9814 while the interrupt service routine might be active.
9820 \begin_inset LatexCommand \ref{sub:Overlaying}
9825 about Overlaying and section
9826 \begin_inset LatexCommand \ref{sub:Functions-using-private-banks}
9831 about Functions using private register banks.
9834 Enabling and Disabling Interrupts
9837 Critical Functions and Critical Statements
9840 A special keyword may be associated with a block or a function declaring
9846 SDCC will generate code to disable all interrupts
9847 \begin_inset LatexCommand \index{interrupt}
9851 upon entry to a critical function and restore the interrupt enable to the
9852 previous state before returning.
9853 Nesting critical functions will need one additional byte on the stack
9854 \begin_inset LatexCommand \index{stack}
9864 \begin_inset LatexCommand \index{critical}
9889 The critical attribute maybe used with other attributes like
9899 may also be used to disable interrupts more locally:
9907 More than one statement could have been included in the block.
9910 Enabling and Disabling Interrupts directly
9914 \begin_inset LatexCommand \index{interrupt}
9918 can also be disabled and enabled directly (8051):
9923 EA = 0;\SpecialChar ~
9986 EA = 1;\SpecialChar ~
10053 On other architectures which have seperate opcodes for enabling and disabling
10054 interrupts you might want to make use of defines with inline assembly
10055 \begin_inset LatexCommand \index{Assembler routines}
10065 \begin_inset LatexCommand \index{\_asm}
10074 \begin_inset LatexCommand \index{\_endasm}
10083 #define SEI _asm\SpecialChar ~
10095 Note: it is sometimes sufficient to disable only a specific interrupt source
10097 a timer or serial interrupt by manipulating an
10100 \begin_inset LatexCommand \index{interrupt mask}
10110 Usually the time during which interrupts are disabled should be kept as
10112 This minimizes both
10117 \begin_inset LatexCommand \index{interrupt latency}
10121 (the time between the occurrence of the interrupt and the execution of
10122 the first code in the interrupt routine) and
10127 \begin_inset LatexCommand \index{interrupt jitter}
10131 (the difference between the shortest and the longest interrupt latency).
10132 These really are something different, f.e.
10133 a serial interrupt has to be served before its buffer overruns so it cares
10134 for the maximum interrupt latency, whereas it does not care about jitter.
10135 On a loudspeaker driven via a digital to analog converter which is fed
10136 by an interrupt a latency of a few milliseconds might be tolerable, whereas
10137 a much smaller jitter will be very audible.
10140 You can reenable interrupts within an interrupt routine and on some architecture
10141 s you can make use of two (or more) levels of
10143 interrupt priorities
10146 \begin_inset LatexCommand \index{interrupt priority}
10151 On some architectures which don't support interrupt priorities these can
10152 be implemented by manipulating the interrupt mask and reenabling interrupts
10153 within the interrupt routine.
10154 Don't add complexity unless you have to.
10158 Functions using private register banks
10159 \begin_inset LatexCommand \label{sub:Functions-using-private-banks}
10166 Some architectures have support for quickly changing register sets.
10167 SDCC supports this feature with the
10170 \begin_inset LatexCommand \index{using (mcs51, ds390 register bank)}
10176 attribute (which tells the compiler to use a register bank
10177 \begin_inset LatexCommand \index{register bank (mcs51, ds390)}
10181 other than the default bank zero).
10182 It should only be applied to
10185 \begin_inset LatexCommand \index{interrupt}
10191 functions (see footnote below).
10192 This will in most circumstances make the generated ISR code more efficient
10193 since it will not have to save registers on the stack.
10200 attribute will have no effect on the generated code for a
10204 function (but may occasionally be useful anyway
10210 possible exception: if a function is called ONLY from 'interrupt' functions
10211 using a particular bank, it can be declared with the same 'using' attribute
10212 as the calling 'interrupt' functions.
10213 For instance, if you have several ISRs using bank one, and all of them
10214 call memcpy(), it might make sense to create a specialized version of memcpy()
10215 'using 1', since this would prevent the ISR from having to save bank zero
10216 to the stack on entry and switch to bank zero before calling the function
10223 (pending: I don't think this has been done yet)
10230 function using a non-zero bank will assume that it can trash that register
10231 bank, and will not save it.
10232 Since high-priority interrupts
10233 \begin_inset LatexCommand \index{interrupt priority}
10237 can interrupt low-priority ones on the 8051 and friends, this means that
10238 if a high-priority ISR
10242 a particular bank occurs while processing a low-priority ISR
10246 the same bank, terrible and bad things can happen.
10247 To prevent this, no single register bank should be
10251 by both a high priority and a low priority ISR.
10252 This is probably most easily done by having all high priority ISRs use
10253 one bank and all low priority ISRs use another.
10254 If you have an ISR which can change priority at runtime, you're on your
10255 own: I suggest using the default bank zero and taking the small performance
10259 It is most efficient if your ISR calls no other functions.
10260 If your ISR must call other functions, it is most efficient if those functions
10261 use the same bank as the ISR (see note 1 below); the next best is if the
10262 called functions use bank zero.
10263 It is very inefficient to call a function using a different, non-zero bank
10269 \begin_inset LatexCommand \label{sub:Startup-Code}
10274 \begin_inset LatexCommand \index{Startup code}
10281 MCS51/DS390 Startup Code
10284 The compiler inserts a call to the C routine
10286 _sdcc_external_startup()
10287 \begin_inset LatexCommand \index{\_sdcc\_external\_startup()}
10296 at the start of the CODE area.
10297 This routine is in the runtime library
10298 \begin_inset LatexCommand \index{Runtime library}
10303 By default this routine returns 0, if this routine returns a non-zero value,
10304 the static & global variable initialization will be skipped and the function
10305 main will be invoked.
10306 Otherwise static & global variables will be initialized before the function
10310 _sdcc_external_startup()
10312 routine to your program to override the default if you need to setup hardware
10313 or perform some other critical operation prior to static & global variable
10315 On some mcs51 variants xdata has to be explicitly enabled before it can
10316 be accessed, this is the place to do it.
10317 See also the compiler option
10336 \begin_inset LatexCommand \index{-\/-no-xinit-opt}
10341 \begin_inset LatexCommand \ref{sub:MCS51-variants}
10346 about MCS51-variants.
10352 The HC08 startup code follows the same scheme as the MCS51 startup code.
10358 On the Z80 the startup code is inserted by linking with crt0.o which is generated
10359 from sdcc/device/lib/z80/crt0.s.
10360 If you need a different startup code you can use the compiler option
10381 \begin_inset LatexCommand \index{-\/-no-std-crt0}
10385 and provide your own crt0.o.
10389 Inline Assembler Code
10390 \begin_inset LatexCommand \index{Assembler routines}
10397 A Step by Step Introduction
10398 \begin_inset LatexCommand \label{sub:A-Step-by Assembler Introduction}
10405 Starting from a small snippet of c-code this example shows for the MCS51
10406 how to use inline assembly, access variables, a function parameter and
10407 an array in xdata memory.
10408 The example uses an MCS51 here but is easily adapted for other architectures.
10409 This is a buffer routine which should be optimized:
10416 \begin_inset LatexCommand \index{far (storage class)}
10421 \begin_inset LatexCommand \index{at}
10426 \begin_inset LatexCommand \index{Aligned array}
10432 unsigned char head,tail;
10436 void to_buffer( unsigned char c )
10444 if( head != tail-1 )
10459 If the code snippet (assume it is saved in buffer.c) is compiled with SDCC
10460 then a corresponding buffer.asm file is generated.
10461 We define a new function
10465 in file buffer.c in which we cut and paste the generated code, removing
10466 unwanted comments and some ':'.
10468 \begin_inset Quotes sld
10472 \begin_inset Quotes srd
10476 \begin_inset Quotes sld
10480 \begin_inset Quotes srd
10483 to the beginning and the end of the function body:
10489 /* With a cut and paste from the .asm file, we have something to start with.
10494 The function is not yet OK! (registers aren't saved) */
10496 void to_buffer_asm( unsigned char c )
10505 \begin_inset LatexCommand \index{\_asm}
10519 ;buffer.c if( head != tail-1 )
10567 ;buffer.c buf[ head++ ] = c; /* access to a 256 byte aligned array */
10568 \begin_inset LatexCommand \index{Aligned array}
10637 The new file buffer.c should compile with only one warning about the unreferenced
10638 function argument 'c'.
10639 Now we hand-optimize the assembly code and insert an #define USE_ASSEMBLY
10640 (1) and finally have:
10646 unsigned char far at 0x7f00 buf[0x100];
10648 unsigned char head,tail;
10650 #define USE_ASSEMBLY (1)
10658 void to_buffer( unsigned char c )
10666 if( head != tail-1 )
10686 void to_buffer( unsigned char c )
10694 c; // to avoid warning: unreferenced function argument
10701 \begin_inset LatexCommand \index{\_asm}
10715 ; save used registers here.
10726 ; If we were still using r2,r3 we would have to push them here.
10729 ; if( head != tail-1 )
10772 ; we could do an ANL a,#0x0f here to use a smaller buffer (see below)
10796 ; buf[ head++ ] = c;
10807 a,dpl \SpecialChar ~
10814 ; dpl holds lower byte of function argument
10825 dpl,_head \SpecialChar ~
10828 ; buf is 0x100 byte aligned so head can be used directly
10870 ; we could do an ANL _head,#0x0f here to use a smaller buffer (see above)
10882 ; restore used registers here
10895 The inline assembler code can contain any valid code understood by the assembler
10896 , this includes any assembler directives and comment lines
10902 The assembler does not like some characters like ':' or ''' in comments.
10903 You'll find an 100+ pages assembler manual in sdcc/as/doc/asxhtm.html
10907 The compiler does not do any validation of the code within the
10910 \begin_inset LatexCommand \index{\_asm}
10918 Specifically it will not know which registers are used and thus register
10920 \begin_inset LatexCommand \index{push/pop}
10924 has to be done manually.
10928 It is recommended that each assembly instruction (including labels) be placed
10929 in a separate line (as the example shows).
10943 \begin_inset LatexCommand \index{-\/-peep-asm}
10949 command line option is used, the inline assembler code will be passed through
10950 the peephole optimizer
10951 \begin_inset LatexCommand \index{Peephole optimizer}
10956 There are only a few (if any) cases where this option makes sense, it might
10957 cause some unexpected changes in the inline assembler code.
10958 Please go through the peephole optimizer rules defined in file
10962 before using this option.
10966 \begin_inset LatexCommand \label{sub:Naked-Functions}
10971 \begin_inset LatexCommand \index{Naked functions}
10978 A special keyword may be associated with a function declaring it as
10981 \begin_inset LatexCommand \index{\_naked}
10992 function modifier attribute prevents the compiler from generating prologue
10993 \begin_inset LatexCommand \index{function prologue}
10998 \begin_inset LatexCommand \index{function epilogue}
11002 code for that function.
11003 This means that the user is entirely responsible for such things as saving
11004 any registers that may need to be preserved, selecting the proper register
11005 bank, generating the
11009 instruction at the end, etc.
11010 Practically, this means that the contents of the function must be written
11011 in inline assembler.
11012 This is particularly useful for interrupt functions, which can have a large
11013 (and often unnecessary) prologue/epilogue.
11014 For example, compare the code generated by these two functions:
11020 \begin_inset LatexCommand \index{volatile}
11024 data unsigned char counter;
11028 void simpleInterrupt(void) interrupt
11029 \begin_inset LatexCommand \index{interrupt}
11047 void nakedInterrupt(void) interrupt 2 _naked
11056 \begin_inset LatexCommand \index{\_asm}
11073 _counter ; does not change flags, no need to save psw
11085 ; MUST explicitly include ret or reti in _naked function.
11092 \begin_inset LatexCommand \index{\_endasm}
11101 For an 8051 target, the generated simpleInterrupt looks like:
11242 whereas nakedInterrupt looks like:
11257 _counter ; does not change flags, no need to save psw
11275 ; MUST explicitly include ret or reti in _naked function
11278 The related directive #pragma exclude
11279 \begin_inset LatexCommand \index{\#pragma exclude}
11283 allows a more fine grained control over pushing & popping
11284 \begin_inset LatexCommand \index{push/pop}
11291 While there is nothing preventing you from writing C code inside a
11295 function, there are many ways to shoot yourself in the foot doing this,
11296 and it is recommended that you stick to inline assembler.
11299 Use of Labels within Inline Assembler
11302 SDCC allows the use of in-line assembler with a few restrictions regarding
11304 In older versions of the compiler all labels defined within inline assembler
11313 where nnnn is a number less than 100 (which implies a limit of utmost 100
11314 inline assembler labels
11328 \begin_inset LatexCommand \index{\_asm}
11358 \begin_inset LatexCommand \index{\_endasm}
11365 Inline assembler code cannot reference any C-Labels, however it can reference
11367 \begin_inset LatexCommand \index{Labels}
11371 defined by the inline assembler, e.g.:
11396 ; some assembler code
11416 /* some more c code */
11418 clabel:\SpecialChar ~
11420 /* inline assembler cannot reference this label */
11432 $0003: ;label (can be referenced by inline assembler only)
11444 /* some more c code */
11449 In other words inline assembly code can access labels defined in inline
11450 assembly within the scope of the function.
11451 The same goes the other way, i.e.
11452 labels defines in inline assembly can not be accessed by C statements.
11455 Interfacing with Assembler Code
11456 \begin_inset LatexCommand \index{Assembler routines}
11463 Global Registers used for Parameter Passing
11464 \begin_inset LatexCommand \index{Parameter passing}
11471 The compiler always uses the global registers
11474 \begin_inset LatexCommand \index{DPTR, DPH, DPL}
11479 \begin_inset LatexCommand \index{DPTR}
11484 \begin_inset LatexCommand \index{B (mcs51, ds390 register)}
11493 \begin_inset LatexCommand \index{ACC (mcs51, ds390 register)}
11499 to pass the first parameter to a routine.
11500 The second parameter onwards is either allocated on the stack (for reentrant
11511 -stack-auto is used) or in data / xdata memory (depending on the memory
11516 Assembler Routine (non-reentrant)
11519 In the following example
11520 \begin_inset LatexCommand \index{reentrant}
11525 \begin_inset LatexCommand \index{Assembler routines (non-reentrant)}
11529 the function c_func calls an assembler routine asm_func, which takes two
11531 \begin_inset LatexCommand \index{function parameter}
11540 extern int asm_func(unsigned char, unsigned char);
11544 int c_func (unsigned char i, unsigned char j)
11552 return asm_func(i,j);
11566 return c_func(10,9);
11571 The corresponding assembler function is:
11576 .globl _asm_func_PARM_2
11677 \begin_inset LatexCommand \index{DPTR, DPH, DPL}
11694 Note here that the return values
11695 \begin_inset LatexCommand \index{return value}
11699 are placed in 'dpl' - One byte return value, 'dpl' LSB & 'dph' MSB for
11701 'dpl', 'dph' and 'b' for three byte values (generic pointers) and 'dpl','dph','
11702 b' & 'acc' for four byte values.
11705 The parameter naming convention is _<function_name>_PARM_<n>, where n is
11706 the parameter number starting from 1, and counting from the left.
11707 The first parameter is passed in
11708 \begin_inset Quotes eld
11712 \begin_inset Quotes erd
11715 for a one byte parameter,
11716 \begin_inset Quotes eld
11720 \begin_inset Quotes erd
11724 \begin_inset Quotes eld
11728 \begin_inset Quotes erd
11731 for three bytes and
11732 \begin_inset Quotes eld
11736 \begin_inset Quotes erd
11739 for a four bytes parameter.
11740 The variable name for the second parameter will be _<function_name>_PARM_2.
11744 Assemble the assembler routine with the following command:
11751 asx8051 -losg asmfunc.asm
11758 Then compile and link the assembler routine to the C source file with the
11766 sdcc cfunc.c asmfunc.rel
11769 Assembler Routine (reentrant)
11773 \begin_inset LatexCommand \index{reentrant}
11778 \begin_inset LatexCommand \index{Assembler routines (reentrant)}
11782 the second parameter
11783 \begin_inset LatexCommand \index{function parameter}
11787 onwards will be passed on the stack, the parameters are pushed from right
11789 after the call the leftmost parameter will be on the top of the stack.
11790 Here is an example:
11795 extern int asm_func(unsigned char, unsigned char);
11799 int c_func (unsigned char i, unsigned char j) reentrant
11807 return asm_func(i,j);
11821 return c_func(10,9);
11826 The corresponding assembler routine is:
11926 The compiling and linking procedure remains the same, however note the extra
11927 entry & exit linkage required for the assembler code, _bp is the stack
11928 frame pointer and is used to compute the offset into the stack for parameters
11929 and local variables.
11933 \begin_inset LatexCommand \index{int (16 bit)}
11938 \begin_inset LatexCommand \index{long (32 bit)}
11945 For signed & unsigned int (16 bit) and long (32 bit) variables, division,
11946 multiplication and modulus operations are implemented by support routines.
11947 These support routines are all developed in ANSI-C to facilitate porting
11948 to other MCUs, although some model specific assembler optimizations are
11950 The following files contain the described routines, all of them can be
11951 found in <installdir>/share/sdcc/lib.
11957 \begin_inset Tabular
11958 <lyxtabular version="3" rows="11" columns="2">
11960 <column alignment="center" valignment="top" leftline="true" width="0">
11961 <column alignment="center" valignment="top" leftline="true" rightline="true" width="0">
11962 <row topline="true" bottomline="true">
11963 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
11973 <cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
11984 <row topline="true">
11985 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
11993 <cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
11998 16 bit multiplication
12002 <row topline="true">
12003 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
12011 <cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
12016 signed 16 bit division (calls _divuint)
12020 <row topline="true">
12021 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
12029 <cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
12034 unsigned 16 bit division
12038 <row topline="true">
12039 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
12047 <cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
12052 signed 16 bit modulus (calls _moduint)
12056 <row topline="true">
12057 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
12065 <cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
12070 unsigned 16 bit modulus
12074 <row topline="true">
12075 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
12083 <cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
12088 32 bit multiplication
12092 <row topline="true">
12093 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
12101 <cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
12106 signed 32 division (calls _divulong)
12110 <row topline="true">
12111 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
12119 <cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
12124 unsigned 32 division
12128 <row topline="true">
12129 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
12137 <cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
12142 signed 32 bit modulus (calls _modulong)
12146 <row topline="true" bottomline="true">
12147 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
12155 <cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
12160 unsigned 32 bit modulus
12173 Since they are compiled as
12178 \begin_inset LatexCommand \index{reentrant}
12183 \begin_inset LatexCommand \index{interrupt}
12187 service routines should not do any of the above operations.
12188 If this is unavoidable then the above routines will need to be compiled
12202 \begin_inset LatexCommand \index{-\/-stack-auto}
12208 option, after which the source program will have to be compiled with
12221 \begin_inset LatexCommand \index{-\/-int-long-reent}
12228 Notice that you don't have to call these routines directly.
12229 The compiler will use them automatically every time an integer operation
12233 Floating Point Support
12234 \begin_inset LatexCommand \index{Floating point support}
12241 SDCC supports IEEE (single precision 4 bytes) floating point numbers.The
12242 floating point support routines are derived from gcc's floatlib.c and consist
12243 of the following routines:
12251 \begin_inset Tabular
12252 <lyxtabular version="3" rows="17" columns="2">
12254 <column alignment="center" valignment="top" leftline="true" width="0">
12255 <column alignment="center" valignment="top" leftline="true" rightline="true" width="0">
12256 <row topline="true" bottomline="true">
12257 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
12274 <cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
12283 <row topline="true">
12284 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
12301 <cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
12315 add floating point numbers
12319 <row topline="true">
12320 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
12337 <cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
12351 subtract floating point numbers
12355 <row topline="true">
12356 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
12373 <cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
12387 divide floating point numbers
12391 <row topline="true">
12392 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
12409 <cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
12423 multiply floating point numbers
12427 <row topline="true">
12428 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
12445 <cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
12459 convert floating point to unsigned char
12463 <row topline="true">
12464 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
12481 <cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
12495 convert floating point to signed char
12499 <row topline="true">
12500 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
12517 <cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
12531 convert floating point to unsigned int
12535 <row topline="true">
12536 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
12553 <cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
12567 convert floating point to signed int
12571 <row topline="true">
12572 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
12598 <cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
12612 convert floating point to unsigned long
12616 <row topline="true">
12617 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
12634 <cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
12648 convert floating point to signed long
12652 <row topline="true">
12653 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
12670 <cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
12684 convert unsigned char to floating point
12688 <row topline="true">
12689 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
12706 <cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
12720 convert char to floating point number
12724 <row topline="true">
12725 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
12742 <cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
12756 convert unsigned int to floating point
12760 <row topline="true">
12761 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
12778 <cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
12792 convert int to floating point numbers
12796 <row topline="true">
12797 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
12814 <cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
12828 convert unsigned long to floating point number
12832 <row topline="true" bottomline="true">
12833 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
12850 <cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
12864 convert long to floating point number
12877 These support routines are developed in ANSI-C so there is room for space
12878 and speed improvement.
12879 Note if all these routines are used simultaneously the data space might
12881 For serious floating point usage it is recommended that the large model
12883 Also notice that you don't have to call this routines directly.
12884 The compiler will use them automatically every time a floating point operation
12889 \begin_inset LatexCommand \index{Libraries}
12898 <pending: this is messy and incomplete - a little more information is in
12899 sdcc/doc/libdoc.txt
12904 Compiler support routines (_gptrget, _mulint etc.)
12907 Stdclib functions (puts, printf, strcat etc.)
12908 \layout Subsubsection
12914 \begin_inset LatexCommand \index{<stdio.h>}
12918 As usual on embedded systems you have to provide your own
12921 \begin_inset LatexCommand \index{getchar()}
12930 \begin_inset LatexCommand \index{putchar()}
12937 SDCC does not know whether the system connects to a serial line with or
12938 without handshake, LCD, keyboard or other device.
12939 You'll find examples for serial routines f.e.
12940 in sdcc/device/lib.
12943 If you're short on memory you might want to use
12954 \begin_inset LatexCommand \index{printf()}
12961 For the mcs51 there is an assembly version
12965 which should fit the requirements of many embedded systems (by unsetting
12966 #defines it can be customized to
12970 support long variables and field widths).
12973 Math functions (sin, pow, sqrt etc.)
12980 \begin_inset LatexCommand \index{Libraries}
12984 included in SDCC should have a license at least as liberal as the GNU Lesser
12985 General Public License
12986 \begin_inset LatexCommand \index{GNU Lesser General Public License, LGPL}
12997 license statements for the libraries are missing.
12998 sdcc/device/lib/ser_ir.c
13002 come with a GPL (as opposed to LGPL) License - this will not be liberal
13003 enough for many embedded programmers.
13006 If you have ported some library or want to share experience about some code
13008 falls into any of these categories Busses (I
13009 \begin_inset Formula $^{\textrm{2}}$
13012 C, CAN, Ethernet, Profibus, Modbus, USB, SPI, JTAG ...), Media (IDE, Memory
13013 cards, eeprom, flash...), En-/Decryption, Remote debugging, Realtime kernel,
13014 Keyboard, LCD, RTC, FPGA, PID then the sdcc-user mailing list
13015 \begin_inset LatexCommand \url{http://sourceforge.net/mail/?group_id=599}
13020 would certainly like to hear about it.
13021 Programmers coding for embedded systems are not especially famous for being
13022 enthusiastic, so don't expect a big hurray but as the mailing list is searchabl
13023 e these references are very valuable.
13024 Let's help to create a climate where information is shared.
13030 MCS51 Memory Models
13031 \begin_inset LatexCommand \index{Memory model}
13036 \begin_inset LatexCommand \index{MCS51 memory model}
13041 \layout Subsubsection
13046 SDCC allows two memory models for MCS51 code,
13055 Modules compiled with different memory models should
13059 be combined together or the results would be unpredictable.
13060 The library routines supplied with the compiler are compiled as both small
13062 The compiled library modules are contained in separate directories as small
13063 and large so that you can link to either set.
13067 When the large model is used all variables declared without a storage class
13068 will be allocated into the external ram, this includes all parameters and
13069 local variables (for non-reentrant
13070 \begin_inset LatexCommand \index{reentrant}
13075 When the small model is used variables without storage class are allocated
13076 in the internal ram.
13079 Judicious usage of the processor specific storage classes
13080 \begin_inset LatexCommand \index{Storage class}
13084 and the 'reentrant' function type will yield much more efficient code,
13085 than using the large model.
13086 Several optimizations are disabled when the program is compiled using the
13087 large model, it is therefore recommended that the small model be used unless
13088 absolutely required.
13089 \layout Subsubsection
13092 \begin_inset LatexCommand \label{sub:External-Stack}
13097 \begin_inset LatexCommand \index{stack}
13102 \begin_inset LatexCommand \index{External stack (mcs51)}
13109 The external stack (-
13120 \begin_inset LatexCommand \index{-\/-xstack}
13124 ) is located in pdata
13125 \begin_inset LatexCommand \index{pdata (mcs51, ds390 storage class)}
13129 memory (usually at the start of the external ram segment) and is 256 bytes
13141 -xstack option is used to compile the program, the parameters and local
13143 \begin_inset LatexCommand \index{local variables}
13147 of all reentrant functions are allocated in this area.
13148 This option is provided for programs with large stack space requirements.
13149 When used with the -
13160 \begin_inset LatexCommand \index{-\/-stack-auto}
13164 option, all parameters and local variables are allocated on the external
13165 stack (note: support libraries will need to be recompiled with the same
13169 The compiler outputs the higher order address byte of the external ram segment
13171 \begin_inset LatexCommand \index{P2 (mcs51 sfr)}
13176 \begin_inset LatexCommand \ref{sub:MCS51-variants}
13180 ), therefore when using the External Stack option, this port
13184 be used by the application program.
13188 \begin_inset LatexCommand \index{Memory model}
13193 \begin_inset LatexCommand \index{DS390 memory model}
13200 The only model supported is Flat 24
13201 \begin_inset LatexCommand \index{Flat 24 (DS390 memory model)}
13206 This generates code for the 24 bit contiguous addressing mode of the Dallas
13208 In this mode, up to four meg of external RAM or code space can be directly
13210 See the data sheets at www.dalsemi.com for further information on this part.
13214 Note that the compiler does not generate any code to place the processor
13215 into 24 bitmode (although
13219 in the ds390 libraries will do that for you).
13225 \begin_inset LatexCommand \index{Tinibios (DS390)}
13229 , the boot loader or similar code must ensure that the processor is in 24
13230 bit contiguous addressing mode before calling the SDCC startup code.
13248 option, variables will by default be placed into the XDATA segment.
13253 Segments may be placed anywhere in the 4 meg address space using the usual
13265 Note that if any segments are located above 64K, the -r flag must be passed
13266 to the linker to generate the proper segment relocations, and the Intel
13267 HEX output format must be used.
13268 The -r flag can be passed to the linker by using the option
13272 on the SDCC command line.
13273 However, currently the linker can not handle code segments > 64k.
13277 \begin_inset LatexCommand \index{Pragmas}
13284 SDCC supports the following #pragma directives:
13288 \begin_inset LatexCommand \index{\#pragma save}
13292 - this will save all current options to the save/restore stack.
13297 \begin_inset LatexCommand \index{\#pragma restore}
13301 - will restore saved options from the last save.
13302 saves & restores can be nested.
13303 SDCC uses a save/restore stack: save pushes current options to the stack,
13304 restore pulls current options from the stack.
13309 \begin_inset LatexCommand \index{\#pragma nogcse}
13313 - will stop global common subexpression elimination.
13317 \begin_inset LatexCommand \index{\#pragma noinduction}
13321 - will stop loop induction optimizations.
13325 \begin_inset LatexCommand \index{\#pragma nojtbound}
13329 - will not generate code for boundary value checking, when switch statements
13330 are turned into jump-tables (dangerous).
13331 For more details see section
13332 \begin_inset LatexCommand \ref{sub:'switch'-Statements}
13340 \begin_inset LatexCommand \index{\#pragma nooverlay}
13344 - the compiler will not overlay the parameters and local variables of a
13349 \begin_inset LatexCommand \index{\#pragma less\_pedantic}
13353 - the compiler will not warn you anymore for obvious mistakes, you'r on
13358 \begin_inset LatexCommand \index{\#pragma noloopreverse}
13362 - Will not do loop reversal optimization
13366 \begin_inset LatexCommand \index{\#pragma exclude}
13370 none | {acc[,b[,dpl[,dph]]] - The exclude pragma disables generation of
13372 \begin_inset LatexCommand \index{push/pop}
13376 instruction in ISR function (using interrupt
13377 \begin_inset LatexCommand \index{interrupt}
13382 The directive should be placed immediately before the ISR function definition
13383 and it affects ALL ISR functions following it.
13384 To enable the normal register saving for ISR functions use #pragma\SpecialChar ~
13385 exclude\SpecialChar ~
13387 \begin_inset LatexCommand \index{\#pragma exclude}
13395 \begin_inset LatexCommand \index{\#pragma noiv}
13399 - Do not generate interrupt
13400 \begin_inset LatexCommand \index{interrupt}
13404 vector table entries for all ISR functions defined after the pragma.
13405 This is useful in cases where the interrupt vector table must be defined
13406 manually, or when there is a secondary, manually defined interrupt vector
13408 for the autovector feature of the Cypress EZ-USB FX2).
13409 More elegantly this can be achieved by obmitting the optional interrupt
13410 number after the interrupt keyword, see section
13411 \begin_inset LatexCommand \ref{sub:Interrupt-Service-Routines}
13420 \begin_inset LatexCommand \index{\#pragma callee\_saves}
13425 \begin_inset LatexCommand \index{function prologue}
13429 function1[,function2[,function3...]] - The compiler by default uses a caller
13430 saves convention for register saving across function calls, however this
13431 can cause unnecessary register pushing & popping
13432 \begin_inset LatexCommand \index{push/pop}
13436 when calling small functions from larger functions.
13437 This option can be used to switch off the register saving convention for
13438 the function names specified.
13439 The compiler will not save registers when calling these functions, extra
13440 code need to be manually inserted at the entry & exit for these functions
13441 to save & restore the registers used by these functions, this can SUBSTANTIALLY
13442 reduce code & improve run time performance of the generated code.
13443 In the future the compiler (with inter procedural analysis) may be able
13444 to determine the appropriate scheme to use for each function call.
13455 -callee-saves command line option is used, the function names specified
13456 in #pragma\SpecialChar ~
13458 \begin_inset LatexCommand \index{\#pragma callee\_saves}
13462 is appended to the list of functions specified in the command line.
13465 SDCPP supports the following #pragma directives:
13469 \begin_inset LatexCommand \index{\#pragma preproc\_asm}
13473 (+ | -) - switch _asm _endasm block preprocessing on / off.
13477 The pragma's are intended to be used to turn-on or off certain optimizations
13478 which might cause the compiler to generate extra stack / data space to
13479 store compiler generated temporary variables.
13480 This usually happens in large functions.
13481 Pragma directives should be used as shown in the following example, they
13482 are used to control options & optimizations for a given function; pragmas
13483 should be placed before and/or after a function, placing pragma's inside
13484 a function body could have unpredictable results.
13490 \begin_inset LatexCommand \index{\#pragma save}
13501 /* save the current settings */
13504 \begin_inset LatexCommand \index{\#pragma nogcse}
13513 /* turnoff global subexpression elimination */
13515 #pragma noinduction
13516 \begin_inset LatexCommand \index{\#pragma noinduction}
13520 /* turn off induction optimizations */
13543 \begin_inset LatexCommand \index{\#pragma restore}
13547 /* turn the optimizations back on */
13550 The compiler will generate a warning message when extra space is allocated.
13551 It is strongly recommended that the save and restore pragma's be used when
13552 changing options for a function.
13555 Defines Created by the Compiler
13558 The compiler creates the following #defines
13559 \begin_inset LatexCommand \index{\#defines}
13564 \begin_inset LatexCommand \index{Defines created by the compiler}
13574 \begin_inset Tabular
13575 <lyxtabular version="3" rows="10" columns="2">
13577 <column alignment="center" valignment="top" leftline="true" width="0">
13578 <column alignment="center" valignment="top" leftline="true" rightline="true" width="0">
13579 <row topline="true" bottomline="true">
13580 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
13590 <cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
13601 <row topline="true">
13602 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
13608 \begin_inset LatexCommand \index{SDCC}
13615 <cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
13620 this Symbol is always defined
13624 <row topline="true">
13625 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
13631 \begin_inset LatexCommand \index{SDCC\_mcs51}
13636 \begin_inset LatexCommand \index{SDCC\_ds390}
13641 \begin_inset LatexCommand \index{SDCC\_z80}
13648 <cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
13653 depending on the model used (e.g.: -mds390
13657 <row topline="true">
13658 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
13664 \begin_inset LatexCommand \index{\_\_mcs51}
13669 \begin_inset LatexCommand \index{\_\_ds390}
13674 \begin_inset LatexCommand \index{\_\_hc08}
13679 \begin_inset LatexCommand \index{\_\_z80}
13686 <cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
13691 depending on the model used (e.g.
13696 <row topline="true">
13697 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
13703 \begin_inset LatexCommand \index{SDCC\_STACK\_AUTO}
13710 <cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
13733 <row topline="true">
13734 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
13740 \begin_inset LatexCommand \index{SDCC\_MODEL\_SMALL}
13747 <cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
13770 <row topline="true">
13771 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
13777 \begin_inset LatexCommand \index{SDCC\_MODEL\_LARGE}
13784 <cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
13807 <row topline="true">
13808 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
13814 \begin_inset LatexCommand \index{SDCC\_USE\_XSTACK}
13821 <cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
13844 <row topline="true">
13845 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
13851 \begin_inset LatexCommand \index{SDCC\_STACK\_TENBIT}
13858 <cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
13871 <row topline="true" bottomline="true">
13872 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
13878 \begin_inset LatexCommand \index{SDCC\_MODEL\_FLAT24}
13885 <cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
13907 Debugging with SDCDB
13908 \begin_inset LatexCommand \label{cha:Debugging-with-SDCDB}
13913 \begin_inset LatexCommand \index{sdcdb (debugger)}
13920 SDCC is distributed with a source level debugger
13921 \begin_inset LatexCommand \index{Debugger}
13926 The debugger uses a command line interface, the command repertoire of the
13927 debugger has been kept as close to gdb
13928 \begin_inset LatexCommand \index{gdb}
13932 (the GNU debugger) as possible.
13933 The configuration and build process is part of the standard compiler installati
13934 on, which also builds and installs the debugger in the target directory
13935 specified during configuration.
13936 The debugger allows you debug BOTH at the C source and at the ASM source
13938 Sdcdb is available on Unix platforms only.
13941 Compiling for Debugging
13944 The \SpecialChar \-
13946 debug option must be specified for all files for which debug information
13947 is to be generated.
13948 The complier generates a .adb file for each of these files.
13949 The linker creates the .cdb file from the .adb files and the address information.
13950 This .cdb is used by the debugger.
13953 How the Debugger Works
13966 -debug option is specified the compiler generates extra symbol information
13967 some of which are put into the assembler source and some are put into the
13969 Then the linker creates the .cdb file from the individual .adb files with
13970 the address information for the symbols.
13971 The debugger reads the symbolic information generated by the compiler &
13972 the address information generated by the linker.
13973 It uses the SIMULATOR (Daniel's S51) to execute the program, the program
13974 execution is controlled by the debugger.
13975 When a command is issued for the debugger, it translates it into appropriate
13976 commands for the simulator.
13979 Starting the Debugger
13982 The debugger can be started using the following command line.
13983 (Assume the file you are debugging has the file name foo).
13997 The debugger will look for the following files.
14000 foo.c - the source file.
14003 foo.cdb - the debugger symbol information file.
14006 foo.ihx - the Intel hex format
14007 \begin_inset LatexCommand \index{Intel hex format}
14014 Command Line Options.
14027 -directory=<source file directory> this option can used to specify the directory
14029 The debugger will look into the directory list specified for source, cdb
14031 The items in the directory list must be separated by ':', e.g.
14032 if the source files can be in the directories /home/src1 and /home/src2,
14043 -directory option should be -
14053 -directory=/home/src1:/home/src2.
14054 Note there can be no spaces in the option.
14058 -cd <directory> - change to the <directory>.
14061 -fullname - used by GUI front ends.
14064 -cpu <cpu-type> - this argument is passed to the simulator please see the
14065 simulator docs for details.
14068 -X <Clock frequency > this options is passed to the simulator please see
14069 the simulator docs for details.
14072 -s <serial port file> passed to simulator see the simulator docs for details.
14075 -S <serial in,out> passed to simulator see the simulator docs for details.
14078 -k <port number> passed to simulator see the simulator docs for details.
14084 As mentioned earlier the command interface for the debugger has been deliberatel
14085 y kept as close the GNU debugger gdb, as possible.
14086 This will help the integration with existing graphical user interfaces
14087 (like ddd, xxgdb or xemacs) existing for the GNU debugger.
14088 If you use a graphical user interface for the debugger you can skip the
14090 \layout Subsubsection*
14092 break [line | file:line | function | file:function]
14095 Set breakpoint at specified line or function:
14104 sdcdb>break foo.c:100
14106 sdcdb>break funcfoo
14108 sdcdb>break foo.c:funcfoo
14109 \layout Subsubsection*
14111 clear [line | file:line | function | file:function ]
14114 Clear breakpoint at specified line or function:
14123 sdcdb>clear foo.c:100
14125 sdcdb>clear funcfoo
14127 sdcdb>clear foo.c:funcfoo
14128 \layout Subsubsection*
14133 Continue program being debugged, after breakpoint.
14134 \layout Subsubsection*
14139 Execute till the end of the current function.
14140 \layout Subsubsection*
14145 Delete breakpoint number 'n'.
14146 If used without any option clear ALL user defined break points.
14147 \layout Subsubsection*
14149 info [break | stack | frame | registers ]
14152 info break - list all breakpoints
14155 info stack - show the function call stack.
14158 info frame - show information about the current execution frame.
14161 info registers - show content of all registers.
14162 \layout Subsubsection*
14167 Step program until it reaches a different source line.
14168 Note: pressing <return> repeats the last command.
14169 \layout Subsubsection*
14174 Step program, proceeding through subroutine calls.
14175 \layout Subsubsection*
14180 Start debugged program.
14181 \layout Subsubsection*
14186 Print type information of the variable.
14187 \layout Subsubsection*
14192 print value of variable.
14193 \layout Subsubsection*
14198 load the given file name.
14199 Note this is an alternate method of loading file for debugging.
14200 \layout Subsubsection*
14205 print information about current frame.
14206 \layout Subsubsection*
14211 Toggle between C source & assembly source.
14212 \layout Subsubsection*
14214 ! simulator command
14217 Send the string following '!' to the simulator, the simulator response is
14219 Note the debugger does not interpret the command being sent to the simulator,
14220 so if a command like 'go' is sent the debugger can loose its execution
14221 context and may display incorrect values.
14222 \layout Subsubsection*
14229 My name is Bobby Brown"
14232 Interfacing with XEmacs
14233 \begin_inset LatexCommand \index{XEmacs}
14238 \begin_inset LatexCommand \index{Emacs}
14245 Two files (in emacs lisp) are provided for the interfacing with XEmacs,
14246 sdcdb.el and sdcdbsrc.el.
14247 These two files can be found in the $(prefix)/bin directory after the installat
14249 These files need to be loaded into XEmacs for the interface to work.
14250 This can be done at XEmacs startup time by inserting the following into
14251 your '.xemacs' file (which can be found in your HOME directory):
14257 (load-file sdcdbsrc.el)
14263 .xemacs is a lisp file so the () around the command is REQUIRED.
14264 The files can also be loaded dynamically while XEmacs is running, set the
14265 environment variable 'EMACSLOADPATH' to the installation bin directory
14266 (<installdir>/bin), then enter the following command ESC-x load-file sdcdbsrc.
14267 To start the interface enter the following command:
14281 You will prompted to enter the file name to be debugged.
14286 The command line options that are passed to the simulator directly are bound
14287 to default values in the file sdcdbsrc.el.
14288 The variables are listed below, these values maybe changed as required.
14291 sdcdbsrc-cpu-type '51
14294 sdcdbsrc-frequency '11059200
14297 sdcdbsrc-serial nil
14300 The following is a list of key mapping for the debugger interface.
14308 ;; Current Listing ::
14310 ;;key\SpecialChar ~
14325 binding\SpecialChar ~
14349 ;;---\SpecialChar ~
14364 ------\SpecialChar ~
14404 sdcdb-next-from-src\SpecialChar ~
14430 sdcdb-back-from-src\SpecialChar ~
14456 sdcdb-cont-from-src\SpecialChar ~
14466 SDCDB continue command
14482 sdcdb-step-from-src\SpecialChar ~
14508 sdcdb-whatis-c-sexp\SpecialChar ~
14518 SDCDB ptypecommand for data at
14582 sdcdbsrc-delete\SpecialChar ~
14596 SDCDB Delete all breakpoints if no arg
14644 given or delete arg (C-u arg x)
14660 sdcdbsrc-frame\SpecialChar ~
14675 SDCDB Display current frame if no arg,
14724 given or display frame arg
14789 sdcdbsrc-goto-sdcdb\SpecialChar ~
14799 Goto the SDCDB output buffer
14815 sdcdb-print-c-sexp\SpecialChar ~
14826 SDCDB print command for data at
14890 sdcdbsrc-goto-sdcdb\SpecialChar ~
14900 Goto the SDCDB output buffer
14916 sdcdbsrc-mode\SpecialChar ~
14932 Toggles Sdcdbsrc mode (turns it off)
14936 ;; C-c C-f\SpecialChar ~
14944 sdcdb-finish-from-src\SpecialChar ~
14952 SDCDB finish command
14956 ;; C-x SPC\SpecialChar ~
14964 sdcdb-break\SpecialChar ~
14982 Set break for line with point
14984 ;; ESC t\SpecialChar ~
14994 sdcdbsrc-mode\SpecialChar ~
15010 Toggle Sdcdbsrc mode
15012 ;; ESC m\SpecialChar ~
15022 sdcdbsrc-srcmode\SpecialChar ~
15044 Here are a few guidelines that will help the compiler generate more efficient
15045 code, some of the tips are specific to this compiler others are generally
15046 good programming practice.
15049 Use the smallest data type to represent your data-value.
15050 If it is known in advance that the value is going to be less than 256 then
15051 use an 'unsigned char' instead of a 'short' or 'int'.
15052 Please note, that ANSI C requires both signed and unsigned chars to be
15053 promoted to 'signed int' before doing any operation.
15054 This promotion can be omitted, if the result is the same.
15055 The effect of the promotion rules together with the sign-extension is often
15062 unsigned char uc = 0xfe;
15064 if (uc * uc < 0) /* this is true! */
15083 (int) uc * (int) uc = (int) 0xfe * (int) 0xfe = (int) 0xfc04 = -1024
15093 (unsigned char) -12 / (signed char) -3 = ...
15096 No, the result is not 4:
15101 (int) (unsigned char) -12 / (int) (signed char) -3 =
15103 (int) (unsigned char) 0xf4 / (int) (signed char) 0xfd =
15105 (int) 0x00f4 / (int) 0xfffd =
15107 (int) 0x00f4 / (int) 0xfffd =
15109 (int) 244 / (int) -3 =
15111 (int) -81 = (int) 0xffaf;
15114 Don't complain, that gcc gives you a different result.
15115 gcc uses 32 bit ints, while SDCC uses 16 bit ints.
15116 Therefore the results are different.
15119 \begin_inset Quotes sld
15123 \begin_inset Quotes srd
15129 If well-defined overflow characteristics are important and negative values
15130 are not, or if you want to steer clear of sign-extension problems when
15131 manipulating bits or bytes, use one of the corresponding unsigned types.
15132 (Beware when mixing signed and unsigned values in expressions, though.)
15134 Although character types (especially unsigned char) can be used as "tiny"
15135 integers, doing so is sometimes more trouble than it's worth, due to unpredicta
15136 ble sign extension and increased code size.
15140 Use unsigned when it is known in advance that the value is not going to
15142 This helps especially if you are doing division or multiplication, bit-shifting
15143 or are using an array index.
15146 NEVER jump into a LOOP.
15149 Declare the variables to be local
15150 \begin_inset LatexCommand \index{local variables}
15154 whenever possible, especially loop control variables (induction).
15157 Since the compiler does not always do implicit integral promotion, the programme
15158 r should do an explicit cast when integral promotion is required.
15161 Reducing the size of division, multiplication & modulus operations can reduce
15162 code size substantially.
15163 Take the following code for example.
15169 foobar(unsigned int p1, unsigned char ch)
15177 unsigned char ch1 = p1 % ch ;
15188 For the modulus operation the variable ch will be promoted to unsigned int
15189 first then the modulus operation will be performed (this will lead to a
15190 call to support routine _moduint()), and the result will be casted to a
15192 If the code is changed to
15197 foobar(unsigned int p1, unsigned char ch)
15205 unsigned char ch1 = (unsigned char)p1 % ch ;
15216 It would substantially reduce the code generated (future versions of the
15217 compiler will be smart enough to detect such optimization opportunities).
15221 Have a look at the assembly listing to get a
15222 \begin_inset Quotes sld
15226 \begin_inset Quotes srd
15229 for the code generation.
15233 \begin_inset LatexCommand \index{Tools}
15237 included in the distribution
15241 \begin_inset Tabular
15242 <lyxtabular version="3" rows="12" columns="3">
15244 <column alignment="center" valignment="top" leftline="true" width="0pt">
15245 <column alignment="center" valignment="top" leftline="true" width="0pt">
15246 <column alignment="center" valignment="top" leftline="true" rightline="true" width="0pt">
15247 <row topline="true" bottomline="true">
15248 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
15256 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
15264 <cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
15273 <row topline="true">
15274 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
15282 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
15287 Simulator for various architectures
15290 <cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
15299 <row topline="true">
15300 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
15308 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
15313 header file conversion
15316 <cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
15321 sdcc/support/scripts
15325 <row topline="true">
15326 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
15334 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
15339 header file conversion
15342 <cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
15347 sdcc/support/scripts
15351 <row topline="true">
15352 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
15360 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
15368 <cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
15386 <row topline="true">
15387 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
15395 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
15403 <cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
15421 <row topline="true">
15422 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
15430 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
15438 <cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
15456 <row topline="true">
15457 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
15465 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
15473 <cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
15491 <row topline="true">
15492 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
15500 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
15508 <cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
15526 <row topline="true">
15527 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
15535 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
15543 <cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
15561 <row topline="true">
15562 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
15570 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
15578 <cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
15596 <row topline="true" bottomline="true">
15597 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
15605 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
15613 <cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
15641 \begin_inset LatexCommand \index{Documentation}
15645 included in the distribution
15649 \begin_inset Tabular
15650 <lyxtabular version="3" rows="10" columns="2">
15652 <column alignment="left" valignment="top" leftline="true" width="0">
15653 <column alignment="left" valignment="top" leftline="true" rightline="true" width="0pt">
15654 <row topline="true" bottomline="true">
15655 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
15663 <cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
15668 Where to get / filename
15672 <row topline="true">
15673 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
15678 SDCC Compiler User Guide
15681 <cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
15686 You're reading it right now
15690 <row topline="true">
15691 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
15699 <cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
15708 <row topline="true">
15709 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
15714 ASXXXX Assemblers and ASLINK Relocating Linker
15717 <cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
15722 sdcc/as/doc/asxhtm.html
15726 <row topline="true">
15727 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
15732 SDCC regression test
15733 \begin_inset LatexCommand \index{Regression test}
15740 <cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
15745 sdcc/doc/test_suite_spec.pdf
15749 <row topline="true">
15750 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
15758 <cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
15767 <row topline="true">
15768 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
15773 Notes on debugging with sdcdb
15774 \begin_inset LatexCommand \index{sdcdb (debugger)}
15781 <cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
15786 sdcc/debugger/README
15790 <row topline="true">
15791 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
15796 Software simulator for microcontrollers
15799 <cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
15826 <row topline="true">
15827 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
15832 Temporary notes on the pic16
15833 \begin_inset LatexCommand \index{PIC16}
15840 <cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
15845 sdcc/src/pic16/NOTES
15849 <row topline="true" bottomline="true">
15850 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
15855 SDCC internal documentation (debugging file format)
15858 <cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
15894 Related open source tools
15895 \begin_inset LatexCommand \index{Related tools}
15903 \begin_inset Tabular
15904 <lyxtabular version="3" rows="10" columns="3">
15906 <column alignment="center" valignment="top" leftline="true" width="0pt">
15907 <column alignment="block" valignment="top" leftline="true" width="30line%">
15908 <column alignment="center" valignment="top" leftline="true" rightline="true" width="0pt">
15909 <row topline="true" bottomline="true">
15910 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
15918 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
15926 <cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
15935 <row topline="true">
15936 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
15942 \begin_inset LatexCommand \index{gpsim (PIC simulator)}
15949 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
15957 <cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
15963 \begin_inset LatexCommand \url{http://www.dattalo.com/gnupic/gpsim.html}
15971 <row topline="true">
15972 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
15980 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
15988 <cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
15994 \begin_inset LatexCommand \url{http://digilander.libero.it/fbradasc/FLP5.html}
16002 <row topline="true">
16003 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
16009 \begin_inset LatexCommand \index{indent (source formatting tool)}
16016 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
16021 Formats C source - Master of the white spaces
16024 <cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
16030 \begin_inset LatexCommand \url{http://home.hccnet.nl/d.ingamells/beautify.html}
16038 <row topline="true">
16039 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
16045 \begin_inset LatexCommand \index{srecord (tool)}
16052 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
16057 Object file conversion, checksumming, ...
16060 <cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
16066 \begin_inset LatexCommand \url{http://srecord.sourceforge.net/}
16074 <row topline="true">
16075 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
16081 \begin_inset LatexCommand \index{objdump (tool)}
16088 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
16093 Object file conversion, ...
16096 <cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
16101 Part of binutils (should be there anyway)
16105 <row topline="true">
16106 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
16112 \begin_inset LatexCommand \index{doxygen (source documentation tool)}
16119 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
16124 Source code documentation system
16127 <cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
16133 \begin_inset LatexCommand \url{http://www.doxygen.org}
16141 <row topline="true">
16142 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
16150 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
16155 IDE (has anyone tried integrating SDCC & sdcdb? Unix only)
16158 <cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
16164 \begin_inset LatexCommand \url{http://www.kdevelop.org}
16172 <row topline="true">
16173 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
16179 \begin_inset LatexCommand \index{splint (syntax checking tool)}
16186 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
16191 Statically checks c sources
16194 <cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
16200 \begin_inset LatexCommand \url{http://www.splint.org}
16208 <row topline="true" bottomline="true">
16209 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
16215 \begin_inset LatexCommand \index{ddd (debugger)}
16222 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
16227 Debugger, serves nicely as GUI to sdcdb
16228 \begin_inset LatexCommand \index{sdcdb (debugger)}
16235 <cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
16241 \begin_inset LatexCommand \url{http://www.gnu.org/software/ddd/}
16258 Related documentation / recommended reading
16262 \begin_inset Tabular
16263 <lyxtabular version="3" rows="4" columns="3">
16265 <column alignment="center" valignment="top" leftline="true" width="0pt">
16266 <column alignment="block" valignment="top" leftline="true" width="30line%">
16267 <column alignment="center" valignment="top" leftline="true" rightline="true" width="0pt">
16268 <row topline="true" bottomline="true">
16269 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
16277 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
16285 <cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
16294 <row topline="true">
16295 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
16312 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
16318 \begin_inset LatexCommand \index{C Reference card}
16325 <cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
16331 \begin_inset LatexCommand \url{http://www.refcards.com/about/c.html}
16339 <row topline="true">
16340 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
16348 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
16356 <cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
16362 \begin_inset LatexCommand \url{http://www.eskimo.com/~scs/C-faq/top.html}
16370 <row topline="true" bottomline="true">
16371 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
16381 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
16386 Advanced Compiler Design and Implementation
16389 <cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
16394 bookstore (very dedicated, probably read other books first)
16410 Some questions answered, some pointers given - it might be time to in turn
16418 can you solve your project with the selected microcontroller? Would you
16419 find out early or rather late that your target is too small/slow/whatever?
16420 Can you switch to a slightly better device if it doesn't fit?
16423 should you solve the problem with an 8 bit CPU? Or would a 16/32 bit CPU
16424 and/or another programming language be more adequate? Would an operating
16425 system on the target device help?
16428 if you solved the problem, will the marketing department be happy?
16431 if the marketing department is happy, will customers be happy?
16434 if you're the project manager, marketing department and maybe even the customer
16435 in one person, have you tried to see the project from the outside?
16438 is the project done if you think it is done? Or is just that other interface/pro
16439 tocol/feature/configuration/option missing? How about website, manual(s),
16440 internationalization, packaging, labels, electromagnetic compatability/interfer
16441 ence, documentation for production, production test software, update mechanism,
16445 is your project adequately positioned in that magic triangle: fame, fortune,
16449 Maybe not all answers to these questions are known and some answers may
16454 , nevertheless knowing these questions may help you to avoid burnout
16460 burnout is bad for electronic devices, programmers and motorcycle tyres
16464 Chances are you didn't want to hear some of them...
16468 \begin_inset LatexCommand \index{Support}
16475 SDCC has grown to be a large project.
16476 The compiler alone (without the preprocessor, assembler and linker) is
16477 well over 100,000 lines of code (blank stripped).
16478 The open source nature of this project is a key to its continued growth
16480 You gain the benefit and support of many active software developers and
16482 Is SDCC perfect? No, that's why we need your help.
16483 The developers take pride in fixing reported bugs.
16484 You can help by reporting the bugs and helping other SDCC users.
16485 There are lots of ways to contribute, and we encourage you to take part
16486 in making SDCC a great software package.
16490 The SDCC project is hosted on the SDCC sourceforge site at
16491 \begin_inset LatexCommand \htmlurl{http://sourceforge.net/projects/sdcc}
16496 You'll find the complete set of mailing lists
16497 \begin_inset LatexCommand \index{Mailing list}
16501 , forums, bug reporting system, patch submission
16502 \begin_inset LatexCommand \index{Patch submission}
16507 \begin_inset LatexCommand \index{download}
16511 area and cvs code repository
16512 \begin_inset LatexCommand \index{cvs code repository}
16520 \begin_inset LatexCommand \index{Bug reporting}
16525 \begin_inset LatexCommand \index{Reporting bugs}
16532 The recommended way of reporting bugs is using the infrastructure of the
16534 You can follow the status of bug reports there and have an overview about
16538 Bug reports are automatically forwarded to the developer mailing list and
16539 will be fixed ASAP.
16540 When reporting a bug, it is very useful to include a small test program
16541 (the smaller the better) which reproduces the problem.
16542 If you can isolate the problem by looking at the generated assembly code,
16543 this can be very helpful.
16544 Compiling your program with the -
16555 \begin_inset LatexCommand \index{-\/-dumpall}
16559 option can sometimes be useful in locating optimization problems.
16560 When reporting a bug please maker sure you:
16563 Attach the code you are compiling with SDCC.
16567 Specify the exact command you use to run SDCC, or attach your Makefile.
16571 Specify the SDCC version (type "
16577 "), your platform, and operating system.
16581 Provide an exact copy of any error message or incorrect output.
16585 Put something meaningful in the subject of your message.
16588 Please attempt to include these 5 important parts, as applicable, in all
16589 requests for support or when reporting any problems or bugs with SDCC.
16590 Though this will make your message lengthy, it will greatly improve your
16591 chance that SDCC users and developers will be able to help you.
16592 Some SDCC developers are frustrated by bug reports without code provided
16593 that they can use to reproduce and ultimately fix the problem, so please
16594 be sure to provide sample code if you are reporting a bug!
16597 Please have a short check that you are using a recent version of SDCC and
16598 the bug is not yet known.
16599 This is the link for reporting bugs:
16600 \begin_inset LatexCommand \htmlurl{http://sourceforge.net/tracker/?group_id=599&atid=100599}
16607 Requesting Features
16608 \begin_inset LatexCommand \label{sub:Requesting-Features}
16613 \begin_inset LatexCommand \index{Feature request}
16618 \begin_inset LatexCommand \index{Requesting features}
16625 Like bug reports feature requests are forwarded to the developer mailing
16627 This is the link for requesting features:
16628 \begin_inset LatexCommand \htmlurl{http://sourceforge.net/tracker/?group_id=599&atid=350599}
16638 Like bug reports contributed patches are forwarded to the developer mailing
16640 This is the link for submitting patches
16641 \begin_inset LatexCommand \index{Patch submission}
16646 \begin_inset LatexCommand \url{http://sourceforge.net/tracker/?group_id=599&atid=300599}
16653 You need to specify some parameters to the
16657 command for the patches to be useful.
16658 If you modified more than one file a patch created f.e.
16663 \begin_inset Quotes sld
16666 diff -Naur unmodified_directory modified_directory >my_changes.patch
16667 \begin_inset Quotes srd
16673 will be fine, otherwise
16677 \begin_inset Quotes sld
16680 diff -u sourcefile.c.orig sourcefile.c >my_changes.patch
16681 \begin_inset Quotes srd
16694 These links should take you directly to the
16695 \begin_inset LatexCommand \url[Mailing lists]{http://sourceforge.net/mail/?group_id=599}
16705 Traffic on sdcc-devel and sdcc-user is about 100 mails/month each not counting
16706 automated messages (mid 2003)
16710 \begin_inset LatexCommand \url[Forums]{http://sourceforge.net/forum/?group_id=599}
16714 , lists and forums are archived and searchable so if you are lucky someone
16715 already had a similar problem.
16721 You can follow the status of the cvs version
16722 \begin_inset LatexCommand \index{version}
16726 of SDCC by watching the Changelog
16727 \begin_inset LatexCommand \index{Changelog}
16731 in the cvs-repository
16736 \begin_inset LatexCommand \htmlurl{http://cvs.sourceforge.net/cgi-bin/viewcvs.cgi/*checkout*/sdcc/sdcc/ChangeLog?rev=HEAD&content-type=text/plain}
16744 \begin_inset LatexCommand \index{Release policy}
16751 Historically there often were long delays between official releases and
16752 the sourceforge download area tends to get not updated at all.
16753 Excuses in the past might have referred to problems with live range analysis,
16754 but as this was fixed a while ago, the current problem is that another
16755 excuse has to be found.
16756 Kidding aside, we have to get better there! On the other hand there are
16757 daily snapshots available at
16758 \begin_inset LatexCommand \htmlurl[snap]{http://sdcc.sourceforge.net/snap.php}
16762 , and you can always build the very last version (hopefully with many bugs
16763 fixed, and features added) from the source code available at
16764 \begin_inset LatexCommand \htmlurl[Source]{http://sdcc.sourceforge.net/snap.php#Source}
16772 \begin_inset LatexCommand \index{Examples}
16779 You'll find some small examples in the directory
16781 sdcc/device/examples/.
16784 More examples and libraries are available at
16786 The SDCC Open Knowledge Resource
16787 \begin_inset LatexCommand \url{http://www.qsl.net/dl9sec/SDCC_OKR.html}
16794 \begin_inset LatexCommand \url{http://www.pjrc.com/tech/8051/}
16801 I did insert a reference to Paul's web site here although it seems rather
16802 dedicated to a specific 8032 board (I think it's okay because it f.e.
16803 shows LCD/Harddisc interface and has a free 8051 monitor.
16804 Independent 8032 board vendors face hard competition of heavily subsidized
16805 development boards anyway).
16808 Maybe we should include some links to real world applications.
16809 Preferably pointer to pointers (one for each architecture) so this stays
16814 \begin_inset LatexCommand \index{Quality control}
16821 The compiler is passed through nightly compile and build checks.
16827 \begin_inset LatexCommand \index{Regression test}
16831 check that SDCC itself compiles flawlessly on several platforms and checks
16832 the quality of the code generated by SDCC by running the code through simulator
16834 There is a separate document
16837 \begin_inset LatexCommand \index{Test suite}
16846 You'll find the test code in the directory
16848 sdcc/support/regression
16851 You can run these tests manually by running
16855 in this directory (or f.e.
16860 \begin_inset Quotes sld
16864 \begin_inset Quotes srd
16870 if you don't want to run the complete tests).
16871 The test code might also be interesting if you want to look for examples
16872 \begin_inset LatexCommand \index{Examples}
16876 checking corner cases of SDCC or if you plan to submit patches
16877 \begin_inset LatexCommand \index{Patch submission}
16884 The pic port uses a different set of regression tests, you'll find them
16887 sdcc/src/regression
16892 SDCC Technical Data
16896 \begin_inset LatexCommand \index{Optimizations}
16903 SDCC performs a host of standard optimizations in addition to some MCU specific
16908 Sub-expression Elimination
16909 \begin_inset LatexCommand \index{Subexpression elimination}
16916 The compiler does local and
16942 will be translated to
16954 Some subexpressions are not as obvious as the above example, e.g.:
16964 In this case the address arithmetic a->b[i] will be computed only once;
16965 the equivalent code in C would be.
16977 The compiler will try to keep these temporary variables in registers.
16980 Dead-Code Elimination
16981 \begin_inset LatexCommand \index{Dead-code elimination}
17002 i = 1; \SpecialChar ~
17011 global = 1;\SpecialChar ~
17024 global = 3;\SpecialChar ~
17053 \begin_inset LatexCommand \index{Copy propagation}
17109 Note: the dead stores created by this copy propagation will be eliminated
17110 by dead-code elimination.
17114 \begin_inset LatexCommand \index{Loop optimization}
17121 Two types of loop optimizations are done by SDCC loop invariant lifting
17122 and strength reduction of loop induction variables.
17123 In addition to the strength reduction the optimizer marks the induction
17124 variables and the register allocator tries to keep the induction variables
17125 in registers for the duration of the loop.
17126 Because of this preference of the register allocator
17127 \begin_inset LatexCommand \index{Register allocation}
17131 , loop induction optimization causes an increase in register pressure, which
17132 may cause unwanted spilling of other temporary variables into the stack
17133 \begin_inset LatexCommand \index{stack}
17138 The compiler will generate a warning message when it is forced to allocate
17139 extra space either on the stack or data space.
17140 If this extra space allocation is undesirable then induction optimization
17141 can be eliminated either for the entire source file (with -
17151 -noinduction option) or for a given function only using #pragma\SpecialChar ~
17153 \begin_inset LatexCommand \index{\#pragma noinduction}
17166 for (i = 0 ; i < 100 ; i ++)
17182 for (i = 0; i < 100; i++)
17191 As mentioned previously some loop invariants are not as apparent, all static
17192 address computations are also moved out of the loop.
17197 \begin_inset LatexCommand \index{Strength reduction}
17201 , this optimization substitutes an expression by a cheaper expression:
17206 for (i=0;i < 100; i++)
17224 for (i=0;i< 100;i++) {
17230 ar[itemp1] = itemp2;
17247 The more expensive multiplication
17248 \begin_inset LatexCommand \index{Multiplication}
17252 is changed to a less expensive addition.
17256 \begin_inset LatexCommand \index{Loop reversing}
17263 This optimization is done to reduce the overhead of checking loop boundaries
17264 for every iteration.
17265 Some simple loops can be reversed and implemented using a
17266 \begin_inset Quotes eld
17269 decrement and jump if not zero
17270 \begin_inset Quotes erd
17274 SDCC checks for the following criterion to determine if a loop is reversible
17275 (note: more sophisticated compilers use data-dependency analysis to make
17276 this determination, SDCC uses a more simple minded analysis).
17279 The 'for' loop is of the form
17285 for(<symbol> = <expression>; <sym> [< | <=] <expression>; [<sym>++ | <sym>
17295 The <for body> does not contain
17296 \begin_inset Quotes eld
17300 \begin_inset Quotes erd
17304 \begin_inset Quotes erd
17310 All goto's are contained within the loop.
17313 No function calls within the loop.
17316 The loop control variable <sym> is not assigned any value within the loop
17319 The loop control variable does NOT participate in any arithmetic operation
17323 There are NO switch statements in the loop.
17326 Algebraic Simplifications
17329 SDCC does numerous algebraic simplifications, the following is a small sub-set
17330 of these optimizations.
17335 i = j + 0;\SpecialChar ~
17339 /* changed to: */\SpecialChar ~
17345 i /= 2;\SpecialChar ~
17352 /* changed to: */\SpecialChar ~
17358 i = j - j;\SpecialChar ~
17362 /* changed to: */\SpecialChar ~
17368 i = j / 1;\SpecialChar ~
17372 /* changed to: */\SpecialChar ~
17379 Note the subexpressions
17380 \begin_inset LatexCommand \index{Subexpression}
17384 given above are generally introduced by macro expansions or as a result
17385 of copy/constant propagation.
17388 'switch' Statements
17389 \begin_inset LatexCommand \label{sub:'switch'-Statements}
17394 \begin_inset LatexCommand \index{switch statement}
17401 SDCC changes switch statements to jump tables
17402 \begin_inset LatexCommand \index{jump tables}
17406 when the following conditions are true.
17410 The case labels are in numerical sequence, the labels need not be in order,
17411 and the starting number need not be one or zero.
17417 switch(i) {\SpecialChar ~
17448 case 4: ...\SpecialChar ~
17480 case 5: ...\SpecialChar ~
17512 case 3: ...\SpecialChar ~
17544 case 6: ...\SpecialChar ~
17612 Both the above switch statements will be implemented using a jump-table.
17613 The example to the right side is slightly more efficient as the check for
17614 the lower boundary of the jump-table is not needed.
17618 The number of case labels is at least three, since it takes two conditional
17619 statements to handle the boundary conditions.
17622 The number of case labels is less than 84, since each label takes 3 bytes
17623 and a jump-table can be utmost 256 bytes long.
17626 Switch statements which have gaps in the numeric sequence or those that
17627 have more that 84 case labels can be split into more than one switch statement
17628 for efficient code generation, e.g.:
17678 If the above switch statement is broken down into two switch statements
17717 case 9:\SpecialChar ~
17724 case 10:\SpecialChar ~
17730 case 11:\SpecialChar ~
17736 case 12:\SpecialChar ~
17743 then both the switch statements will be implemented using jump-tables whereas
17744 the unmodified switch statement will not be.
17745 You might also consider inserting dummy cases 0 and 5 to 8 in this example.
17748 The pragma nojtbound
17749 \begin_inset LatexCommand \index{\#pragma nojtbound}
17753 can be used to turn off checking the
17766 It has no effect if a default label is supplied.
17767 Use of this pragma is dangerous: if the switch argument is not matched
17768 by a case statement the processor will happily jump into Nirvana.
17771 Bit-shifting Operations
17772 \begin_inset LatexCommand \index{Bit shifting}
17779 Bit shifting is one of the most frequently used operation in embedded programmin
17781 SDCC tries to implement bit-shift operations in the most efficient way
17797 generates the following code:
17814 In general SDCC will never setup a loop if the shift count is known.
17857 \begin_inset LatexCommand \index{Bit rotation}
17864 A special case of the bit-shift operation is bit rotation
17865 \begin_inset LatexCommand \index{rotating bits}
17869 , SDCC recognizes the following expression to be a left bit-rotation:
17879 char i;\SpecialChar ~
17890 /* unsigned is needed for rotation */
17895 i = ((i << 1) | (i >> 7));
17904 will generate the following code:
17923 SDCC uses pattern matching on the parse tree to determine this operation.Variatio
17924 ns of this case will also be recognized as bit-rotation, i.e.:
17929 i = ((i >> 7) | (i << 1)); /* left-bit rotation */
17932 Nibble and Byte Swapping
17935 Other special cases of the bit-shift operations are nibble or byte swapping
17936 \begin_inset LatexCommand \index{swapping nibbles/bytes}
17940 , SDCC recognizes the following expressions:
17963 i = ((i << 4) | (i >> 4));
17969 j = ((j << 8) | (j >> 8));
17972 and generates a swap instruction for the nibble swapping
17973 \begin_inset LatexCommand \index{Nibble swapping}
17977 or move instructions for the byte swapping
17978 \begin_inset LatexCommand \index{Byte swapping}
17984 \begin_inset Quotes sld
17988 \begin_inset Quotes srd
17991 example can be used to convert from little to big-endian or vice versa.
17992 If you want to change the endianness of a
17996 integer you have to cast to
18003 Note that SDCC stores numbers in little-endian
18009 Usually 8-bit processors don't care much about endianness.
18010 This is not the case for the standard 8051 which only has an instruction
18016 \begin_inset LatexCommand \index{DPTR}
18024 so little-endian is the more efficient byte order.
18028 \begin_inset LatexCommand \index{little-endian}
18033 \begin_inset LatexCommand \index{Endianness}
18038 lowest order first).
18042 \begin_inset LatexCommand \index{Highest Order Bit}
18049 It is frequently required to obtain the highest order bit of an integral
18050 type (long, int, short or char types).
18051 SDCC recognizes the following expression to yield the highest order bit
18052 and generates optimized code for it, e.g.:
18074 hob = (gint >> 15) & 1;
18084 will generate the following code:
18117 000A E5*01\SpecialChar ~
18144 000C 23\SpecialChar ~
18175 000D 54 01\SpecialChar ~
18202 000F F5*02\SpecialChar ~
18230 Variations of this case however will
18235 It is a standard C expression, so I heartily recommend this be the only
18236 way to get the highest order bit, (it is portable).
18237 Of course it will be recognized even if it is embedded in other expressions,
18243 xyz = gint + ((gint >> 15) & 1);
18246 will still be recognized.
18250 \begin_inset LatexCommand \label{sub:Peephole-Optimizer}
18255 \begin_inset LatexCommand \index{Peephole optimizer}
18262 The compiler uses a rule based, pattern matching and re-writing mechanism
18263 for peep-hole optimization.
18268 a peep-hole optimizer by Christopher W.
18269 Fraser (cwfraser@microsoft.com).
18270 A default set of rules are compiled into the compiler, additional rules
18271 may be added with the
18284 \begin_inset LatexCommand \index{-\/-peep-file}
18291 The rule language is best illustrated with examples.
18315 The above rule will change the following assembly
18316 \begin_inset LatexCommand \index{Assembler routines}
18338 Note: All occurrences of a
18342 (pattern variable) must denote the same string.
18343 With the above rule, the assembly sequence:
18353 will remain unmodified.
18357 Other special case optimizations may be added by the user (via
18373 some variants of the 8051 MCU allow only
18382 The following two rules will change all
18401 replace { lcall %1 } by { acall %1 }
18403 replace { ljmp %1 } by { ajmp %1 }
18408 inline-assembler code
18410 is also passed through the peep hole optimizer, thus the peephole optimizer
18411 can also be used as an assembly level macro expander.
18412 The rules themselves are MCU dependent whereas the rule language infra-structur
18413 e is MCU independent.
18414 Peephole optimization rules for other MCU can be easily programmed using
18419 The syntax for a rule is as follows:
18424 rule := replace [ restart ] '{' <assembly sequence> '
18462 <assembly sequence> '
18480 '}' [if <functionName> ] '
18485 <assembly sequence> := assembly instruction (each instruction including
18486 labels must be on a separate line).
18490 The optimizer will apply to the rules one by one from the top in the sequence
18491 of their appearance, it will terminate when all rules are exhausted.
18492 If the 'restart' option is specified, then the optimizer will start matching
18493 the rules again from the top, this option for a rule is expensive (performance)
18494 , it is intended to be used in situations where a transformation will trigger
18495 the same rule again.
18496 An example of this (not a good one, it has side effects) is the following
18519 Note that the replace pattern cannot be a blank, but can be a comment line.
18520 Without the 'restart' option only the innermost 'pop' 'push' pair would
18521 be eliminated, i.e.:
18551 the restart option the rule will be applied again to the resulting code
18552 and then all the pop-push pairs will be eliminated to yield:
18562 A conditional function can be attached to a rule.
18563 Attaching rules are somewhat more involved, let me illustrate this with
18590 The optimizer does a look-up of a function name table defined in function
18595 in the source file SDCCpeeph.c, with the name
18600 If it finds a corresponding entry the function is called.
18601 Note there can be no parameters specified for these functions, in this
18606 is crucial, since the function
18610 expects to find the label in that particular variable (the hash table containin
18611 g the variable bindings is passed as a parameter).
18612 If you want to code more such functions, take a close look at the function
18613 labelInRange and the calling mechanism in source file SDCCpeeph.c.
18614 Currently implemented are
18616 labelInRange, labelRefCount, labelIsReturnOnly, operandsNotSame, xramMovcOption,
18617 24bitMode, portIsDS390, 24bitModeAndPortDS390
18626 I know this whole thing is a little kludgey, but maybe some day we will
18627 have some better means.
18628 If you are looking at this file, you will see the default rules that are
18629 compiled into the compiler, you can add your own rules in the default set
18630 there if you get tired of specifying the -
18644 \begin_inset LatexCommand \index{ANSI-compliance}
18649 \begin_inset LatexCommand \label{sub:ANSI-Compliance}
18656 Deviations from the compliance:
18659 functions are not always reentrant
18660 \begin_inset LatexCommand \index{reentrant}
18667 structures cannot be assigned values directly, cannot be passed as function
18668 parameters or assigned to each other and cannot be a return value from
18695 s1 = s2 ; /* is invalid in SDCC although allowed in ANSI */
18706 struct s foo1 (struct s parms) /* invalid in SDCC although allowed in ANSI
18728 return rets;/* is invalid in SDCC although allowed in ANSI */
18735 \begin_inset LatexCommand \index{long long (not supported)}
18740 \begin_inset LatexCommand \index{int (64 bit) (not supported)}
18748 \begin_inset LatexCommand \index{double (not supported)}
18752 ' precision floating point
18753 \begin_inset LatexCommand \index{Floating point support}
18760 No support for setjmp
18761 \begin_inset LatexCommand \index{setjmp (not supported)}
18766 \begin_inset LatexCommand \index{longjmp (not supported)}
18774 \begin_inset LatexCommand \index{K\&R style}
18778 function declarations are NOT allowed.
18784 foo(i,j) /* this old style of function declarations */
18786 int i,j; /* are valid in ANSI but not valid in SDCC */
18801 functions declared as pointers
18802 \begin_inset LatexCommand \index{Pointer (to function)}
18807 \begin_inset LatexCommand \index{function pointers}
18811 must be dereferenced during the call.
18822 /* has to be called like this */
18824 (*foo)(); /* ANSI standard allows calls to be made like 'foo()' */
18828 Cyclomatic Complexity
18829 \begin_inset LatexCommand \index{Cyclomatic complexity}
18836 Cyclomatic complexity of a function is defined as the number of independent
18837 paths the program can take during execution of the function.
18838 This is an important number since it defines the number test cases you
18839 have to generate to validate the function.
18840 The accepted industry standard for complexity number is 10, if the cyclomatic
18841 complexity reported by SDCC exceeds 10 you should think about simplification
18842 of the function logic.
18843 Note that the complexity level is not related to the number of lines of
18844 code in a function.
18845 Large functions can have low complexity, and small functions can have large
18851 SDCC uses the following formula to compute the complexity:
18856 complexity = (number of edges in control flow graph) - (number of nodes
18857 in control flow graph) + 2;
18861 Having said that the industry standard is 10, you should be aware that in
18862 some cases it be may unavoidable to have a complexity level of less than
18864 For example if you have switch statement with more than 10 case labels,
18865 each case label adds one to the complexity level.
18866 The complexity level is by no means an absolute measure of the algorithmic
18867 complexity of the function, it does however provide a good starting point
18868 for which functions you might look at for further optimization.
18871 Notes on supported Processors
18875 \begin_inset LatexCommand \label{sub:MCS51-variants}
18880 \begin_inset LatexCommand \index{MCS51 variants}
18887 MCS51 processors are available from many vendors and come in many different
18889 While they might differ considerably in respect to Special Function Registers
18890 the core MCS51 is usually not modified or is kept compatible.
18892 \layout Subsubsection*
18894 pdata access by SFR
18897 With the upcome of devices with internal xdata and flash memory devices
18899 \begin_inset LatexCommand \index{P2 (mcs51 sfr)}
18903 as dedicated I/O port is becoming more popular.
18904 Switching the high byte for pdata
18905 \begin_inset LatexCommand \index{pdata (mcs51, ds390 storage class)}
18909 access which was formerly done by port P2 is then achieved by a Special
18911 \begin_inset LatexCommand \index{sfr}
18916 In well-established MCS51 tradition the address of this
18920 is where the chip designers decided to put it.
18921 Needless to say that they didn't agree on a common name either.
18922 As pdata addressing is used in the startup code for the initialization
18923 of xdata variables a separate startup code should be used as described
18925 \begin_inset LatexCommand \ref{sub:Startup-Code}
18930 \layout Subsubsection*
18932 Other Features available by SFR
18935 Some MCS51 variants offer features like Double DPTR
18936 \begin_inset LatexCommand \index{DPTR}
18940 , multiple DPTR, decrementing DPTR, 16x16 Multiply.
18941 These are currently not used for the MCS51 port.
18942 If you absolutely need them you can fall back to inline assembly or submit
18946 The Z80 and gbz80 port
18949 SDCC can target both the Zilog
18950 \begin_inset LatexCommand \index{Z80}
18954 and the Nintendo Gameboy's Z80-like gbz80
18955 \begin_inset LatexCommand \index{gbz80 (GameBoy Z80)}
18960 The Z80 port is passed through the same
18963 \begin_inset LatexCommand \index{Regression test}
18969 as the MCS51 and DS390 ports, so floating point support, support for long
18970 variables and bitfield support is fine.
18971 See mailing lists and forums about interrupt routines.
18974 As always, the code is the authoritative reference - see z80/ralloc.c and
18977 \begin_inset LatexCommand \index{stack}
18981 frame is similar to that generated by the IAR Z80 compiler.
18982 IX is used as the base pointer, HL is used as a temporary register, and
18983 BC and DE are available for holding variables.
18984 IY is currently unused.
18986 \begin_inset LatexCommand \index{return value}
18991 One bad side effect of using IX as the base pointer is that a functions
18992 stack frame is limited to 127 bytes - this will be fixed in a later version.
18998 The port to the Motorola HC08
18999 \begin_inset LatexCommand \index{HC08}
19003 family has been added in October 2003, thank you Erik!
19010 \begin_inset LatexCommand \index{PIC14}
19014 port still requires a major effort from the development community.
19015 However it can work for very simple code.
19021 C code and 14bit PIC code page
19022 \begin_inset LatexCommand \index{code page (pic14)}
19029 \begin_inset LatexCommand \index{RAM bank (pic14)}
19035 The linker organizes allocation for the code page and RAM banks.
19036 It does not have intimate knowledge of the code flow.
19037 It will put all the code section of a single asm file into a single code
19039 In order to make use of multiple code pages, separate asm files must be
19041 The compiler treats all functions of a single C file as being in the same
19042 code page unless it is non static.
19043 The compiler treats all local variables of a single C file as being in
19044 the same RAM bank unless it is an extern.
19048 To get the best follow these guide lines:
19051 make local functions static, as non static functions require code page selection
19055 Make local variables static as extern variables require RAM bank selection
19059 For devices that have multiple code pages it is more efficient to use the
19060 same number of files as pages, i.e.
19061 for the 16F877 use 4 separate files and i.e.
19062 for the 16F874 use 2 separate files.
19063 This way the linker can put the code for each file into different code
19064 pages and the compiler can allocate reusable variables more efficiently
19065 and there's less page selection overhead.
19066 And as for any 8 bit micro (especially for PIC 14 as they have a very simple
19067 instruction set) use 'unsigned char' whereever possible instead of 'int'.
19072 Creating a device include file
19076 For generating a device include file use the support perl script inc2h.pl
19077 kept in directory support/script.
19087 For the interrupt function, use the keyword 'interrupt'
19088 \begin_inset LatexCommand \index{interrupt}
19092 with level number of 0 (PIC14 only has 1 interrupt so this number is only
19093 there to avoid a syntax error - it ought to be fixed).
19099 void Intr(void) interrupt 0
19105 T0IF = 0; /* Clear timer interrupt */
19112 Linking and assembling
19116 For assembling you can use either GPUTILS' gpasm.exe or MPLAB's mpasmwin.exe.
19117 For linking you can use either GPUTIL's gplink or MPLAB's mplink.exe.
19118 If you use MPLAB and an interrupt function then the linker script file
19119 vectors section will need to be enlarged to link with mplink.
19142 sdcc -S -V -mpic14 -p16F877 $<
19156 $(PRJ).hex: $(OBJS)
19166 gplink -m -s $(PRJ).lkr -o $(PRJ).hex $(OBJS)
19188 sdcc -S -V -mpic14 -p16F877 $<
19198 mpasmwin /q /o $*.asm
19202 $(PRJ).hex: $(OBJS)
19212 mplink /v $(PRJ).lkr /m $(PRJ).map /o $(PRJ).hex $(OBJS)
19216 \begin_inset LatexCommand \index{PIC16}
19223 You'll find some additional notes about this port in the file src/pic16/NOTES.
19226 Retargetting for other Processors
19229 The issues for retargetting the compiler are far too numerous to be covered
19231 What follows is a brief description of each of the seven phases of the
19232 compiler and its MCU dependency.
19235 Parsing the source and building the annotated parse tree.
19236 This phase is largely MCU independent (except for the language extensions).
19237 Syntax & semantic checks are also done in this phase, along with some initial
19238 optimizations like back patching labels and the pattern matching optimizations
19239 like bit-rotation etc.
19242 The second phase involves generating an intermediate code which can be easy
19243 manipulated during the later phases.
19244 This phase is entirely MCU independent.
19245 The intermediate code generation assumes the target machine has unlimited
19246 number of registers, and designates them with the name iTemp.
19247 The compiler can be made to dump a human readable form of the code generated
19261 This phase does the bulk of the standard optimizations and is also MCU independe
19263 This phase can be broken down into several sub-phases:
19267 Break down intermediate code (iCode) into basic blocks.
19269 Do control flow & data flow analysis on the basic blocks.
19271 Do local common subexpression elimination, then global subexpression elimination
19273 Dead code elimination
19277 If loop optimizations caused any changes then do 'global subexpression eliminati
19278 on' and 'dead code elimination' again.
19281 This phase determines the live-ranges; by live range I mean those iTemp
19282 variables defined by the compiler that still survive after all the optimization
19284 Live range analysis
19285 \begin_inset LatexCommand \index{Live range analysis}
19289 is essential for register allocation, since these computation determines
19290 which of these iTemps will be assigned to registers, and for how long.
19293 Phase five is register allocation.
19294 There are two parts to this process.
19298 The first part I call 'register packing' (for lack of a better term).
19299 In this case several MCU specific expression folding is done to reduce
19304 The second part is more MCU independent and deals with allocating registers
19305 to the remaining live ranges.
19306 A lot of MCU specific code does creep into this phase because of the limited
19307 number of index registers available in the 8051.
19310 The Code generation phase is (unhappily), entirely MCU dependent and very
19311 little (if any at all) of this code can be reused for other MCU.
19312 However the scheme for allocating a homogenized assembler operand for each
19313 iCode operand may be reused.
19316 As mentioned in the optimization section the peep-hole optimizer is rule
19317 based system, which can reprogrammed for other MCUs.
19321 \begin_inset LatexCommand \index{Compiler internals}
19328 The anatomy of the compiler
19329 \begin_inset LatexCommand \label{sub:The-anatomy-of}
19338 This is an excerpt from an article published in Circuit Cellar Magazine
19340 It's a little outdated (the compiler is much more efficient now and user/develo
19341 per friendly), but pretty well exposes the guts of it all.
19347 The current version of SDCC can generate code for Intel 8051 and Z80 MCU.
19348 It is fairly easy to retarget for other 8-bit MCU.
19349 Here we take a look at some of the internals of the compiler.
19354 \begin_inset LatexCommand \index{Parsing}
19361 Parsing the input source file and creating an AST (Annotated Syntax Tree
19362 \begin_inset LatexCommand \index{Annotated syntax tree}
19367 This phase also involves propagating types (annotating each node of the
19368 parse tree with type information) and semantic analysis.
19369 There are some MCU specific parsing rules.
19370 For example the storage classes, the extended storage classes are MCU specific
19371 while there may be a xdata storage class for 8051 there is no such storage
19372 class for z80 or Atmel AVR.
19373 SDCC allows MCU specific storage class extensions, i.e.
19374 xdata will be treated as a storage class specifier when parsing 8051 C
19375 code but will be treated as a C identifier when parsing z80 or ATMEL AVR
19380 \begin_inset LatexCommand \index{iCode}
19387 Intermediate code generation.
19388 In this phase the AST is broken down into three-operand form (iCode).
19389 These three operand forms are represented as doubly linked lists.
19390 ICode is the term given to the intermediate form generated by the compiler.
19391 ICode example section shows some examples of iCode generated for some simple
19392 C source functions.
19396 \begin_inset LatexCommand \index{Optimizations}
19403 Bulk of the target independent optimizations is performed in this phase.
19404 The optimizations include constant propagation, common sub-expression eliminati
19405 on, loop invariant code movement, strength reduction of loop induction variables
19406 and dead-code elimination.
19409 Live range analysis
19410 \begin_inset LatexCommand \index{Live range analysis}
19417 During intermediate code generation phase, the compiler assumes the target
19418 machine has infinite number of registers and generates a lot of temporary
19420 The live range computation determines the lifetime of each of these compiler-ge
19421 nerated temporaries.
19422 A picture speaks a thousand words.
19423 ICode example sections show the live range annotations for each of the
19425 It is important to note here, each iCode is assigned a number in the order
19426 of its execution in the function.
19427 The live ranges are computed in terms of these numbers.
19428 The from number is the number of the iCode which first defines the operand
19429 and the to number signifies the iCode which uses this operand last.
19432 Register Allocation
19433 \begin_inset LatexCommand \index{Register allocation}
19440 The register allocation determines the type and number of registers needed
19442 In most MCUs only a few registers can be used for indirect addressing.
19443 In case of 8051 for example the registers R0 & R1 can be used to indirectly
19444 address the internal ram and DPTR to indirectly address the external ram.
19445 The compiler will try to allocate the appropriate register to pointer variables
19447 ICode example section shows the operands annotated with the registers assigned
19449 The compiler will try to keep operands in registers as much as possible;
19450 there are several schemes the compiler uses to do achieve this.
19451 When the compiler runs out of registers the compiler will check to see
19452 if there are any live operands which is not used or defined in the current
19453 basic block being processed, if there are any found then it will push that
19454 operand and use the registers in this block, the operand will then be popped
19455 at the end of the basic block.
19459 There are other MCU specific considerations in this phase.
19460 Some MCUs have an accumulator; very short-lived operands could be assigned
19461 to the accumulator instead of a general-purpose register.
19467 Figure II gives a table of iCode operations supported by the compiler.
19468 The code generation involves translating these operations into corresponding
19469 assembly code for the processor.
19470 This sounds overly simple but that is the essence of code generation.
19471 Some of the iCode operations are generated on a MCU specific manner for
19472 example, the z80 port does not use registers to pass parameters so the
19473 SEND and RECV iCode operations will not be generated, and it also does
19474 not support JUMPTABLES.
19481 <Where is Figure II ?>
19485 \begin_inset LatexCommand \index{iCode}
19492 This section shows some details of iCode.
19493 The example C code does not do anything useful; it is used as an example
19494 to illustrate the intermediate code generated by the compiler.
19506 /* This function does nothing useful.
19513 for the purpose of explaining iCode */
19516 short function (data int *x)
19524 short i=10; \SpecialChar ~
19526 /* dead initialization eliminated */
19531 short sum=10; /* dead initialization eliminated */
19544 while (*x) *x++ = *p++;
19558 /* compiler detects i,j to be induction variables */
19562 for (i = 0, j = 10 ; i < 10 ; i++, j
19588 mul += i * 3; \SpecialChar ~
19590 /* this multiplication remains */
19596 gint += j * 3;\SpecialChar ~
19598 /* this multiplication changed to addition */
19612 In addition to the operands each iCode contains information about the filename
19613 and line it corresponds to in the source file.
19614 The first field in the listing should be interpreted as follows:
19619 Filename(linenumber: iCode Execution sequence number : ICode hash table
19620 key : loop depth of the iCode).
19625 Then follows the human readable form of the ICode operation.
19626 Each operand of this triplet form can be of three basic types a) compiler
19627 generated temporary b) user defined variable c) a constant value.
19628 Note that local variables and parameters are replaced by compiler generated
19631 \begin_inset LatexCommand \index{Live range analysis}
19635 are computed only for temporaries (i.e.
19636 live ranges are not computed for global variables).
19638 \begin_inset LatexCommand \index{Register allocation}
19642 are allocated for temporaries only.
19643 Operands are formatted in the following manner:
19648 Operand Name [lr live-from : live-to ] { type information } [ registers
19654 As mentioned earlier the live ranges are computed in terms of the execution
19655 sequence number of the iCodes, for example
19657 the iTemp0 is live from (i.e.
19658 first defined in iCode with execution sequence number 3, and is last used
19659 in the iCode with sequence number 5).
19660 For induction variables such as iTemp21 the live range computation extends
19661 the lifetime from the start to the end of the loop.
19663 The register allocator used the live range information to allocate registers,
19664 the same registers may be used for different temporaries if their live
19665 ranges do not overlap, for example r0 is allocated to both iTemp6 and to
19666 iTemp17 since their live ranges do not overlap.
19667 In addition the allocator also takes into consideration the type and usage
19668 of a temporary, for example itemp6 is a pointer to near space and is used
19669 as to fetch data from (i.e.
19670 used in GET_VALUE_AT_ADDRESS) so it is allocated a pointer register (r0).
19671 Some short lived temporaries are allocated to special registers which have
19672 meaning to the code generator e.g.
19673 iTemp13 is allocated to a pseudo register CC which tells the back end that
19674 the temporary is used only for a conditional jump the code generation makes
19675 use of this information to optimize a compare and jump ICode.
19677 There are several loop optimizations
19678 \begin_inset LatexCommand \index{Loop optimization}
19682 performed by the compiler.
19683 It can detect induction variables iTemp21(i) and iTemp23(j).
19684 Also note the compiler does selective strength reduction
19685 \begin_inset LatexCommand \index{Strength reduction}
19690 the multiplication of an induction variable in line 18 (gint = j * 3) is
19691 changed to addition, a new temporary iTemp17 is allocated and assigned
19692 a initial value, a constant 3 is then added for each iteration of the loop.
19693 The compiler does not change the multiplication
19694 \begin_inset LatexCommand \index{Multiplication}
19698 in line 17 however since the processor does support an 8 * 8 bit multiplication.
19700 Note the dead code elimination
19701 \begin_inset LatexCommand \index{Dead-code elimination}
19705 optimization eliminated the dead assignments in line 7 & 8 to I and sum
19713 Sample.c (5:1:0:0) _entry($9) :
19718 Sample.c(5:2:1:0) proc _function [lr0:0]{function short}
19723 Sample.c(11:3:2:0) iTemp0 [lr3:5]{_near * int}[r2] = recv
19728 Sample.c(11:4:53:0) preHeaderLbl0($11) :
19733 Sample.c(11:5:55:0) iTemp6 [lr5:16]{_near * int}[r0] := iTemp0 [lr3:5]{_near
19739 Sample.c(11:6:5:1) _whilecontinue_0($1) :
19744 Sample.c(11:7:7:1) iTemp4 [lr7:8]{int}[r2 r3] = @[iTemp6 [lr5:16]{_near *
19750 Sample.c(11:8:8:1) if iTemp4 [lr7:8]{int}[r2 r3] == 0 goto _whilebreak_0($3)
19755 Sample.c(11:9:14:1) iTemp7 [lr9:13]{_far * int}[DPTR] := _p [lr0:0]{_far
19761 Sample.c(11:10:15:1) _p [lr0:0]{_far * int} = _p [lr0:0]{_far * int} + 0x2
19767 Sample.c(11:13:18:1) iTemp10 [lr13:14]{int}[r2 r3] = @[iTemp7 [lr9:13]{_far
19773 Sample.c(11:14:19:1) *(iTemp6 [lr5:16]{_near * int}[r0]) := iTemp10 [lr13:14]{int
19779 Sample.c(11:15:12:1) iTemp6 [lr5:16]{_near * int}[r0] = iTemp6 [lr5:16]{_near
19780 * int}[r0] + 0x2 {short}
19785 Sample.c(11:16:20:1) goto _whilecontinue_0($1)
19790 Sample.c(11:17:21:0)_whilebreak_0($3) :
19795 Sample.c(12:18:22:0) iTemp2 [lr18:40]{short}[r2] := 0x0 {short}
19800 Sample.c(13:19:23:0) iTemp11 [lr19:40]{short}[r3] := 0x0 {short}
19805 Sample.c(15:20:54:0)preHeaderLbl1($13) :
19810 Sample.c(15:21:56:0) iTemp21 [lr21:38]{short}[r4] := 0x0 {short}
19815 Sample.c(15:22:57:0) iTemp23 [lr22:38]{int}[r5 r6] := 0xa {int}
19820 Sample.c(15:23:58:0) iTemp17 [lr23:38]{int}[r7 r0] := 0x1e {int}
19825 Sample.c(15:24:26:1)_forcond_0($4) :
19830 Sample.c(15:25:27:1) iTemp13 [lr25:26]{char}[CC] = iTemp21 [lr21:38]{short}[r4]
19836 Sample.c(15:26:28:1) if iTemp13 [lr25:26]{char}[CC] == 0 goto _forbreak_0($7)
19841 Sample.c(16:27:31:1) iTemp2 [lr18:40]{short}[r2] = iTemp2 [lr18:40]{short}[r2]
19842 + ITemp21 [lr21:38]{short}[r4]
19847 Sample.c(17:29:33:1) iTemp15 [lr29:30]{short}[r1] = iTemp21 [lr21:38]{short}[r4]
19853 Sample.c(17:30:34:1) iTemp11 [lr19:40]{short}[r3] = iTemp11 [lr19:40]{short}[r3]
19854 + iTemp15 [lr29:30]{short}[r1]
19859 Sample.c(18:32:36:1:1) iTemp17 [lr23:38]{int}[r7 r0]= iTemp17 [lr23:38]{int}[r7
19865 Sample.c(18:33:37:1) _gint [lr0:0]{int} = _gint [lr0:0]{int} + iTemp17 [lr23:38]{
19871 Sample.c(15:36:42:1) iTemp21 [lr21:38]{short}[r4] = iTemp21 [lr21:38]{short}[r4]
19877 Sample.c(15:37:45:1) iTemp23 [lr22:38]{int}[r5 r6]= iTemp23 [lr22:38]{int}[r5
19883 Sample.c(19:38:47:1) goto _forcond_0($4)
19888 Sample.c(19:39:48:0)_forbreak_0($7) :
19893 Sample.c(20:40:49:0) iTemp24 [lr40:41]{short}[DPTR] = iTemp2 [lr18:40]{short}[r2]
19894 + ITemp11 [lr19:40]{short}[r3]
19899 Sample.c(20:41:50:0) ret iTemp24 [lr40:41]{short}
19904 Sample.c(20:42:51:0)_return($8) :
19909 Sample.c(20:43:52:0) eproc _function [lr0:0]{ ia0 re0 rm0}{function short}
19915 Finally the code generated for this function:
19956 ; ----------------------------------------------
19961 ; function function
19966 ; ----------------------------------------------
19976 ; iTemp0 [lr3:5]{_near * int}[r2] = recv
19988 ; iTemp6 [lr5:16]{_near * int}[r0] := iTemp0 [lr3:5]{_near * int}[r2]
20000 ;_whilecontinue_0($1) :
20010 ; iTemp4 [lr7:8]{int}[r2 r3] = @[iTemp6 [lr5:16]{_near * int}[r0]]
20015 ; if iTemp4 [lr7:8]{int}[r2 r3] == 0 goto _whilebreak_0($3)
20074 ; iTemp7 [lr9:13]{_far * int}[DPTR] := _p [lr0:0]{_far * int}
20093 ; _p [lr0:0]{_far * int} = _p [lr0:0]{_far * int} + 0x2 {short}
20140 ; iTemp10 [lr13:14]{int}[r2 r3] = @[iTemp7 [lr9:13]{_far * int}[DPTR]]
20180 ; *(iTemp6 [lr5:16]{_near * int}[r0]) := iTemp10 [lr13:14]{int}[r2 r3]
20206 ; iTemp6 [lr5:16]{_near * int}[r0] =
20211 ; iTemp6 [lr5:16]{_near * int}[r0] +
20228 ; goto _whilecontinue_0($1)
20240 ; _whilebreak_0($3) :
20250 ; iTemp2 [lr18:40]{short}[r2] := 0x0 {short}
20262 ; iTemp11 [lr19:40]{short}[r3] := 0x0 {short}
20274 ; iTemp21 [lr21:38]{short}[r4] := 0x0 {short}
20286 ; iTemp23 [lr22:38]{int}[r5 r6] := 0xa {int}
20305 ; iTemp17 [lr23:38]{int}[r7 r0] := 0x1e {int}
20334 ; iTemp13 [lr25:26]{char}[CC] = iTemp21 [lr21:38]{short}[r4] < 0xa {short}
20339 ; if iTemp13 [lr25:26]{char}[CC] == 0 goto _forbreak_0($7)
20384 ; iTemp2 [lr18:40]{short}[r2] = iTemp2 [lr18:40]{short}[r2] +
20389 ; iTemp21 [lr21:38]{short}[r4]
20415 ; iTemp15 [lr29:30]{short}[r1] = iTemp21 [lr21:38]{short}[r4] * 0x3 {short}
20448 ; iTemp11 [lr19:40]{short}[r3] = iTemp11 [lr19:40]{short}[r3] +
20453 ; iTemp15 [lr29:30]{short}[r1]
20472 ; iTemp17 [lr23:38]{int}[r7 r0]= iTemp17 [lr23:38]{int}[r7 r0]- 0x3 {short}
20519 ; _gint [lr0:0]{int} = _gint [lr0:0]{int} + iTemp17 [lr23:38]{int}[r7 r0]
20566 ; iTemp21 [lr21:38]{short}[r4] = iTemp21 [lr21:38]{short}[r4] + 0x1 {short}
20578 ; iTemp23 [lr22:38]{int}[r5 r6]= iTemp23 [lr22:38]{int}[r5 r6]- 0x1 {short}
20592 cjne r5,#0xff,00104$
20604 ; goto _forcond_0($4)
20616 ; _forbreak_0($7) :
20626 ; ret iTemp24 [lr40:41]{short}
20669 A few words about basic block successors, predecessors and dominators
20672 Successors are basic blocks
20673 \begin_inset LatexCommand \index{Basic blocks}
20677 that might execute after this basic block.
20679 Predecessors are basic blocks that might execute before reaching this basic
20682 Dominators are basic blocks that WILL execute before reaching this basic
20716 a) succList of [BB2] = [BB4], of [BB3] = [BB4], of [BB1] = [BB2,BB3]
20719 b) predList of [BB2] = [BB1], of [BB3] = [BB1], of [BB4] = [BB2,BB3]
20722 c) domVect of [BB4] = BB1 ...
20723 here we are not sure if BB2 or BB3 was executed but we are SURE that BB1
20731 \begin_inset LatexCommand \url{http://sdcc.sourceforge.net#Who}
20741 Thanks to all the other volunteer developers who have helped with coding,
20742 testing, web-page creation, distribution sets, etc.
20743 You know who you are :-)
20750 This document was initially written by Sandeep Dutta
20753 All product names mentioned herein may be trademarks
20754 \begin_inset LatexCommand \index{Trademarks}
20758 of their respective companies.
20765 To avoid confusion, the installation and building options for SDCC itself
20766 (chapter 2) are not part of the index.
20770 \begin_inset LatexCommand \printindex{}