1 #LyX 1.3 created this file. For more info see http://www.lyx.org/
15 \use_numerical_citations 0
16 \paperorientation portrait
19 \paragraph_separation indent
21 \quotes_language swedish
29 Please note: double dashed longoptions (e.g.
30 --version) need three dashes in this document to be visable in html and
34 SDCC Compiler User Guide
38 \begin_inset LatexCommand \tableofcontents{}
55 is a Freeware, retargettable, optimizing ANSI-C compiler by
59 designed for 8 bit Microprocessors.
60 The current version targets Intel MCS51 based Microprocessors(8051,8052,
61 etc), Zilog Z80 based MCUs, and the Dallas DS80C390 variant.
62 It can be retargetted for other microprocessors, support for PIC, AVR and
63 186 is under development.
64 The entire source code for the compiler is distributed under GPL.
65 SDCC uses ASXXXX & ASLINK, a Freeware, retargettable assembler & linker.
66 SDCC has extensive language extensions suitable for utilizing various microcont
67 rollers and underlying hardware effectively.
72 In addition to the MCU specific optimizations SDCC also does a host of standard
76 global sub expression elimination,
79 loop optimizations (loop invariant, strength reduction of induction variables
83 constant folding & propagation,
99 For the back-end SDCC uses a global register allocation scheme which should
100 be well suited for other 8 bit MCUs.
105 The peep hole optimizer uses a rule based substitution mechanism which is
111 Supported data-types are:
114 char (8 bits, 1 byte),
117 short and int (16 bits, 2 bytes),
120 long (32 bit, 4 bytes)
127 The compiler also allows
129 inline assembler code
131 to be embedded anywhere in a function.
132 In addition, routines developed in assembly can also be called.
136 SDCC also provides an option (--cyclomatic) to report the relative complexity
138 These functions can then be further optimized, or hand coded in assembly
144 SDCC also comes with a companion source level debugger SDCDB, the debugger
145 currently uses ucSim a freeware simulator for 8051 and other micro-controllers.
150 The latest version can be downloaded from
151 \begin_inset LatexCommand \url{http://sdcc.sourceforge.net/}
163 All packages used in this compiler system are
171 ; source code for all the sub-packages (pre-processor, assemblers, linkers
172 etc) is distributed with the package.
173 This documentation is maintained using a freeware word processor (LyX).
175 This program is free software; you can redistribute it and/or modify it
176 under the terms of the GNU General Public License as published by the Free
177 Software Foundation; either version 2, or (at your option) any later version.
178 This program is distributed in the hope that it will be useful, but WITHOUT
179 ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS
180 FOR A PARTICULAR PURPOSE.
181 See the GNU General Public License for more details.
182 You should have received a copy of the GNU General Public License along
183 with this program; if not, write to the Free Software Foundation, 59 Temple
184 Place - Suite 330, Boston, MA 02111-1307, USA.
185 In other words, you are welcome to use, share and improve this program.
186 You are forbidden to forbid anyone else to use, share and improve what
188 Help stamp out software-hoarding!
191 Typographic conventions
194 Throughout this manual, we will use the following convention.
195 Commands you have to type in are printed in
203 Code samples are printed in
208 Interesting items and new terms are printed in
213 Compatibility with previous versions
216 This version has numerous bug fixes compared with the previous version.
217 But we also introduced some incompatibilities with older versions.
218 Not just for the fun of it, but to make the compiler more stable, efficient
225 short is now equivalent to int (16 bits), it used to be equivalent to char
226 (8 bits) which is not ANSI compliant
229 the default directory for gcc-builds where include, library and documention
230 files are stored is now in /usr/local/share
233 char type parameters to vararg functions are casted to int unless explicitly
250 will push a as an int and as a char resp.
253 option ---regextend has been removed
256 option ---noregparms has been removed
259 option ---stack-after-data has been removed
264 <pending: more incompatibilities?>
270 What do you need before you start installation of SDCC? A computer, and
272 The preferred method of installation is to compile SDCC from source using
274 For Windows some pre-compiled binary distributions are available for your
276 You should have some experience with command line tools and compiler use.
282 The SDCC home page at
283 \begin_inset LatexCommand \url{http://sdcc.sourceforge.net/}
287 is a great place to find distribution sets.
288 You can also find links to the user mailing lists that offer help or discuss
289 SDCC with other SDCC users.
290 Web links to other SDCC related sites can also be found here.
291 This document can be found in the DOC directory of the source package as
293 Some of the other tools (simulator and assembler) included with SDCC contain
294 their own documentation and can be found in the source distribution.
295 If you want the latest unreleased software, the complete source package
296 is available directly by anonymous CVS on cvs.sdcc.sourceforge.net.
299 Wishes for the future
302 There are (and always will be) some things that could be done.
303 Here are some I can think of:
310 char KernelFunction3(char p) at 0x340;
316 If you can think of some more, please send them to the list.
322 <pending: And then of course a proper index-table
323 \begin_inset LatexCommand \index{index}
336 The install paths and default search paths are defined when running 'configure'.
337 The defaults can be overriden by
345 These configure variables are compiled into the binaries, and can only be
346 changed by rerunning 'configure' and recompiling SDCC.
347 The configure variables are written in
351 to distinguish them from run time environment variables (see section search
356 Cygwin is handled like a *nix, Mingw32 however belongs to the Win32 builds.
357 The SDCC team uses Mingw32 to build the official Windows binaries, because
364 a gcc compiler and last but not least
367 the binaries can be built by cross compiling on Sourceforge's compile farm.
370 The other Win32 builds using Borland, VC or whatever don't use 'configure',
371 but they (hopefully) use the default Win32 paths.
381 <lyxtabular version="3" rows="8" columns="3">
383 <column alignment="left" valignment="top" leftline="true" width="0in">
384 <column alignment="left" valignment="top" leftline="true" width="0in">
385 <column alignment="left" valignment="top" leftline="true" rightline="true" width="0in">
386 <row topline="true" bottomline="true">
387 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
395 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
403 <cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
413 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
423 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
431 <cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
443 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
453 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
463 <cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
475 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
485 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
497 <cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
513 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
523 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
535 <cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
547 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
557 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
569 <cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
585 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
595 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
603 <cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
612 <row topline="true" bottomline="true">
613 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
623 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
631 <cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
650 'configure' also computes relative paths.
651 This is needed for full relocatability of a binary package and to complete
652 search paths (see section search paths below):
658 <lyxtabular version="3" rows="4" columns="3">
660 <column alignment="left" valignment="top" leftline="true" width="0in">
661 <column alignment="left" valignment="top" leftline="true" width="0in">
662 <column alignment="left" valignment="top" leftline="true" rightline="true" width="0in">
663 <row topline="true" bottomline="true">
664 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
672 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
680 <cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
689 <row topline="true" bottomline="true">
690 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
700 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
708 <cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
719 <row bottomline="true">
720 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
730 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
738 <cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
747 <row bottomline="true">
748 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
758 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
766 <cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
785 Binary files (preprocessor, assembler and linker)
790 <lyxtabular version="3" rows="2" columns="3">
792 <column alignment="left" valignment="top" leftline="true" width="0in">
793 <column alignment="left" valignment="top" leftline="true" width="0in">
794 <column alignment="left" valignment="top" leftline="true" rightline="true" width="0in">
795 <row topline="true" bottomline="true">
796 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
804 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
812 <cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
821 <row topline="true" bottomline="true">
822 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
832 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
840 <cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
867 <lyxtabular version="3" rows="2" columns="3">
869 <column alignment="block" valignment="top" leftline="true" width="1.6in">
870 <column alignment="center" valignment="top" leftline="true" width="0in">
871 <column alignment="center" valignment="top" leftline="true" rightline="true" width="0in">
872 <row topline="true" bottomline="true">
873 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
881 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
889 <cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
898 <row topline="true" bottomline="true">
899 <cell alignment="left" valignment="top" topline="true" leftline="true" usebox="none">
911 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
916 /usr/local/share/sdcc/include
919 <cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
945 is auto-appended by the compiler, e.g.
946 small, large, z80, ds390 etc.)
951 <lyxtabular version="3" rows="2" columns="3">
953 <column alignment="left" valignment="top" leftline="true" width="0in">
954 <column alignment="left" valignment="top" leftline="true" width="0in">
955 <column alignment="left" valignment="top" leftline="true" rightline="true" width="0in">
956 <row topline="true" bottomline="true">
957 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
965 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
973 <cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
982 <row topline="true" bottomline="true">
983 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
990 $DATADIR/$LIB_DIR_SUFFIX
993 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
998 /usr/local/share/sdcc/lib
1001 <cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
1027 \begin_inset Tabular
1028 <lyxtabular version="3" rows="2" columns="3">
1030 <column alignment="left" valignment="top" leftline="true" width="0in">
1031 <column alignment="left" valignment="top" leftline="true" width="0in">
1032 <column alignment="left" valignment="top" leftline="true" rightline="true" width="0in">
1033 <row topline="true" bottomline="true">
1034 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
1042 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
1050 <cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
1059 <row topline="true" bottomline="true">
1060 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
1070 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
1075 /usr/local/share/sdcc/doc
1078 <cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
1101 Some search paths or parts of them are determined by configure variables
1106 , see section above).
1107 Further search paths are determined by environment variables during runtime.
1110 The paths searched when running the compiler are as follows (the first catch
1116 Binary files (preprocessor, assembler and linker)
1119 \begin_inset Tabular
1120 <lyxtabular version="3" rows="4" columns="3">
1122 <column alignment="left" valignment="top" leftline="true" width="0in">
1123 <column alignment="left" valignment="top" leftline="true" width="0in">
1124 <column alignment="left" valignment="top" leftline="true" rightline="true" width="0in">
1125 <row topline="true" bottomline="true">
1126 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
1134 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
1142 <cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
1151 <row topline="true">
1152 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
1162 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
1170 <cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
1181 <row topline="true">
1182 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
1187 Path of argv[0] (if available)
1190 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
1198 <cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
1207 <row topline="true" bottomline="true">
1208 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
1216 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
1224 <cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
1245 \begin_inset Tabular
1246 <lyxtabular version="3" rows="6" columns="3">
1248 <column alignment="block" valignment="top" leftline="true" width="1.5in">
1249 <column alignment="block" valignment="top" leftline="true" width="1.5in">
1250 <column alignment="left" valignment="top" leftline="true" rightline="true" width="0in">
1251 <row topline="true" bottomline="true">
1252 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
1260 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
1268 <cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
1277 <row topline="true">
1278 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
1286 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
1294 <cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
1303 <row topline="true">
1304 <cell alignment="left" valignment="top" topline="true" leftline="true" usebox="none">
1312 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
1320 <cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
1329 <row topline="true">
1330 <cell alignment="left" valignment="top" topline="true" leftline="true" usebox="none">
1344 <cell alignment="left" valignment="top" topline="true" leftline="true" usebox="none">
1356 <cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
1367 <row topline="true">
1368 <cell alignment="left" valignment="top" topline="true" leftline="true" usebox="none">
1386 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
1396 <cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
1409 <row topline="true" bottomline="true">
1410 <cell alignment="left" valignment="top" topline="true" leftline="true" usebox="none">
1426 <cell alignment="left" valignment="top" topline="true" leftline="true" usebox="none">
1431 /usr/local/share/sdcc/
1436 <cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
1453 The option ---nostdinc disables the last two search paths.
1460 With the exception of
1461 \begin_inset Quotes sld
1465 \begin_inset Quotes srd
1472 is auto-appended by the compiler (e.g.
1473 small, large, z80, ds390 etc.).
1477 \begin_inset Tabular
1478 <lyxtabular version="3" rows="6" columns="3">
1480 <column alignment="block" valignment="top" leftline="true" width="1.7in">
1481 <column alignment="block" valignment="top" leftline="true" width="1.2in">
1482 <column alignment="block" valignment="top" leftline="true" rightline="true" width="1.2in">
1483 <row topline="true" bottomline="true">
1484 <cell alignment="left" valignment="top" topline="true" leftline="true" usebox="none">
1492 <cell alignment="left" valignment="top" topline="true" leftline="true" usebox="none">
1500 <cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
1509 <row topline="true">
1510 <cell alignment="left" valignment="top" topline="true" leftline="true" usebox="none">
1518 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
1526 <cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
1535 <row topline="true">
1536 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
1548 <cell alignment="left" valignment="top" topline="true" leftline="true" usebox="none">
1560 <cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
1575 <row topline="true">
1576 <cell alignment="left" valignment="top" topline="true" leftline="true" usebox="none">
1587 $LIB_DIR_SUFFIX/<model>
1590 <cell alignment="left" valignment="top" topline="true" leftline="true" usebox="none">
1604 <cell alignment="left" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
1621 <row topline="true">
1622 <cell alignment="left" valignment="top" topline="true" leftline="true" usebox="none">
1637 $LIB_DIR_SUFFIX/<model>
1640 <cell alignment="left" valignment="top" topline="true" leftline="true" usebox="none">
1652 <cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
1671 <row topline="true" bottomline="true">
1672 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
1681 $LIB_DIR_SUFFIX/<model>
1684 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
1689 /usr/local/share/sdcc/
1696 <cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
1712 Don't delete any of the stray spaces in the table above without checking
1713 the HTML output (last line)!
1719 The option ---nostdlib disables the last two search paths.
1722 Linux and other gcc-based systems (cygwin, mingw32, osx)
1727 Download the source package
1729 either from the SDCC CVS repository or from the
1730 \begin_inset LatexCommand \url[nightly snapshots]{http://sdcc.sourceforge.net/snap.php}
1736 , it will be named something like sdcc
1749 Bring up a command line terminal, such as xterm.
1754 Unpack the file using a command like:
1757 "tar -xzf sdcc.src.tar.gz
1762 , this will create a sub-directory called sdcc with all of the sources.
1765 Change directory into the main SDCC directory, for example type:
1782 This configures the package for compilation on your system.
1798 All of the source packages will compile, this can take a while.
1814 This copies the binary executables, the include files, the libraries and
1815 the documentation to the install directories.
1818 On OSX 2.x it was reported, that the default gcc (version 3.1 20020420 (prerelease
1819 )) fails to compile SDCC.
1820 Fortunately there's also gcc 2.9.x installed, which works fine.
1821 This compiler can be selected by running 'configure' with:
1824 ./configure CC=gcc2 CXX=g++2
1828 \layout Subsubsection
1830 Windows Install Using a Binary Package
1833 Download the binary package and unpack it using your favorite unpacking
1834 tool (gunzip, WinZip, etc).
1835 This should unpack to a group of sub-directories.
1836 An example directory structure after unpacking the mingw32 package is:
1843 bin for the executables, c:
1863 lib for the include and libraries.
1866 Adjust your environment variable PATH to include the location of the bin
1867 directory or start sdcc using the full path.
1868 \layout Subsubsection
1870 Windows Install Using Cygwin and Mingw32
1873 Follow the instruction in
1875 Linux and other gcc-based systems
1878 \layout Subsubsection
1880 Windows Install Using Microsoft Visual C++ 6.0/NET
1885 Download the source package
1887 either from the SDCC CVS repository or from the
1888 \begin_inset LatexCommand \url[nightly snapshots]{http://sdcc.sourceforge.net/snap.php}
1894 , it will be named something like sdcc
1901 SDCC is distributed with all the projects, workspaces, and files you need
1902 to build it using Visual C++ 6.0/NET.
1903 The workspace name is 'sdcc.dsw'.
1904 Please note that as it is now, all the executables are created in a folder
1908 Once built you need to copy the executables from sdcc
1912 bin before runnng SDCC.
1917 In order to build SDCC with Visual C++ 6.0/NET you need win32 executables
1918 of bison.exe, flex.exe, and gawk.exe.
1919 One good place to get them is
1920 \begin_inset LatexCommand \url[here]{http://unxutils.sourceforge.net}
1928 Download the file UnxUtils.zip.
1929 Now you have to install the utilities and setup Visual C++ so it can locate
1930 the required programs.
1931 Here there are two alternatives (choose one!):
1938 a) Extract UnxUtils.zip to your C:
1940 hard disk PRESERVING the original paths, otherwise bison won't work.
1941 (If you are using WinZip make certain that 'Use folder names' is selected)
1945 b) In the Visual C++ IDE click Tools, Options, select the Directory tab,
1946 in 'Show directories for:' select 'Executable files', and in the directories
1947 window add a new path: 'C:
1957 (As a side effect, you get a bunch of Unix utilities that could be useful,
1958 such as diff and patch.)
1965 This one avoids extracting a bunch of files you may not use, but requires
1970 a) Create a directory were to put the tools needed, or use a directory already
1978 b) Extract 'bison.exe', 'bison.hairy', 'bison.simple', 'flex.exe', and gawk.exe
1979 to such directory WITHOUT preserving the original paths.
1980 (If you are using WinZip make certain that 'Use folder names' is not selected)
1984 c) Rename bison.exe to '_bison.exe'.
1988 d) Create a batch file 'bison.bat' in 'C:
1992 ' and add these lines:
2012 _bison %1 %2 %3 %4 %5 %6 %7 %8 %9
2016 Steps 'c' and 'd' are needed because bison requires by default that the
2017 files 'bison.simple' and 'bison.hairy' reside in some weird Unix directory,
2018 '/usr/local/share/' I think.
2019 So it is necessary to tell bison where those files are located if they
2020 are not in such directory.
2021 That is the function of the environment variables BISON_SIMPLE and BISON_HAIRY.
2025 e) In the Visual C++ IDE click Tools, Options, select the Directory tab,
2026 in 'Show directories for:' select 'Executable files', and in the directories
2027 window add a new path: 'c:
2030 Note that you can use any other path instead of 'c:
2032 util', even the path where the Visual C++ tools are, probably: 'C:
2036 Microsoft Visual Studio
2041 So you don't have to execute step 'e' :)
2045 Open 'sdcc.dsw' in Visual Studio, click 'build all', when it finishes copy
2046 the executables from sdcc
2050 bin, and you can compile using sdcc.
2051 \layout Subsubsection
2053 Windows Install Using Borland
2056 From the sdcc directory, run the command "make -f Makefile.bcc".
2057 This should regenerate all the .exe files in the bin directory except for
2058 sdcdb.exe (which currently doesn't build under Borland C++).
2061 If you modify any source files and need to rebuild, be aware that the dependanci
2062 es may not be correctly calculated.
2063 The safest option is to delete all .obj files and run the build again.
2064 From a Cygwin BASH prompt, this can easily be done with the commmand:
2074 ( -name '*.obj' -o -name '*.lib' -o -name '*.rul'
2076 ) -print -exec rm {}
2085 or on Windows NT/2000/XP from the command prompt with the commmand:
2092 del /s *.obj *.lib *.rul
2095 from the sdcc directory.
2098 Testing out the SDCC Compiler
2101 The first thing you should do after installing your SDCC compiler is to
2109 at the prompt, and the program should run and tell you the version.
2110 If it doesn't run, or gives a message about not finding sdcc program, then
2111 you need to check over your installation.
2112 Make sure that the sdcc bin directory is in your executable search path
2113 defined by the PATH environment setting (see the Trouble-shooting section
2115 Make sure that the sdcc program is in the bin folder, if not perhaps something
2116 did not install correctly.
2124 is commonly installed as described in section
2125 \begin_inset Quotes sld
2128 Install and search paths
2129 \begin_inset Quotes srd
2138 Make sure the compiler works on a very simple example.
2139 Type in the following test.c program using your favorite
2174 Compile this using the following command:
2183 If all goes well, the compiler will generate a test.asm and test.rel file.
2184 Congratulations, you've just compiled your first program with SDCC.
2185 We used the -c option to tell SDCC not to link the generated code, just
2186 to keep things simple for this step.
2194 The next step is to try it with the linker.
2204 If all goes well the compiler will link with the libraries and produce
2205 a test.ihx output file.
2210 (no test.ihx, and the linker generates warnings), then the problem is most
2211 likely that sdcc cannot find the
2215 usr/local/share/sdcc/lib directory
2219 (see the Install trouble-shooting section for suggestions).
2227 The final test is to ensure sdcc can use the
2231 header files and libraries.
2232 Edit test.c and change it to the following:
2252 strcpy(str1, "testing");
2261 Compile this by typing
2268 This should generate a test.ihx output file, and it should give no warnings
2269 such as not finding the string.h file.
2270 If it cannot find the string.h file, then the problem is that sdcc cannot
2271 find the /usr/local/share/sdcc/include directory
2275 (see the Install trouble-shooting section for suggestions).
2278 Install Trouble-shooting
2279 \layout Subsubsection
2281 SDCC does not build correctly.
2284 A thing to try is starting from scratch by unpacking the .tgz source package
2285 again in an empty directory.
2293 ./configure 2>&1 | tee configure.log
2307 make 2>&1 | tee make.log
2314 If anything goes wrong, you can review the log files to locate the problem.
2315 Or a relevant part of this can be attached to an email that could be helpful
2316 when requesting help from the mailing list.
2317 \layout Subsubsection
2320 \begin_inset Quotes sld
2324 \begin_inset Quotes srd
2331 \begin_inset Quotes sld
2335 \begin_inset Quotes srd
2338 command is a script that analyzes your system and performs some configuration
2339 to ensure the source package compiles on your system.
2340 It will take a few minutes to run, and will compile a few tests to determine
2341 what compiler features are installed.
2342 \layout Subsubsection
2345 \begin_inset Quotes sld
2349 \begin_inset Quotes srd
2355 This runs the GNU make tool, which automatically compiles all the source
2356 packages into the final installed binary executables.
2357 \layout Subsubsection
2360 \begin_inset Quotes sld
2364 \begin_inset Quotes erd
2370 This will install the compiler, other executables libraries and include
2371 files in to the appropriate directories.
2373 \begin_inset Quotes sld
2376 Install and Search PATHS
2377 \begin_inset Quotes srd
2382 On most systems you will need super-user privilages to do this.
2388 SDCC is not just a compiler, but a collection of tools by various developers.
2389 These include linkers, assemblers, simulators and other components.
2390 Here is a summary of some of the components.
2391 Note that the included simulator and assembler have separate documentation
2392 which you can find in the source package in their respective directories.
2393 As SDCC grows to include support for other processors, other packages from
2394 various developers are included and may have their own sets of documentation.
2398 You might want to look at the files which are installed in <installdir>.
2399 At the time of this writing, we find the following programs for gcc-builds:
2403 In <installdir>/bin:
2406 sdcc - The compiler.
2409 sdcpp - The C preprocessor.
2412 asx8051 - The assembler for 8051 type processors.
2419 as-gbz80 - The Z80 and GameBoy Z80 assemblers.
2422 aslink -The linker for 8051 type processors.
2429 link-gbz80 - The Z80 and GameBoy Z80 linkers.
2432 s51 - The ucSim 8051 simulator.
2435 sdcdb - The source debugger.
2438 packihx - A tool to pack (compress) Intel hex files.
2441 In <installdir>/share/sdcc/include
2447 In <installdir>/share/sdcc/lib
2450 the subdirs src and small, large, z80, gbz80 and ds390 with the precompiled
2454 In <installdir>/share/sdcc/doc
2460 As development for other processors proceeds, this list will expand to include
2461 executables to support processors like AVR, PIC, etc.
2462 \layout Subsubsection
2467 This is the actual compiler, it in turn uses the c-preprocessor and invokes
2468 the assembler and linkage editor.
2469 \layout Subsubsection
2471 sdcpp - The C-Preprocessor
2474 The preprocessor is a modified version of the GNU preprocessor.
2475 The C preprocessor is used to pull in #include sources, process #ifdef
2476 statements, #defines and so on.
2477 \layout Subsubsection
2479 asx8051, as-z80, as-gbz80, aslink, link-z80, link-gbz80 - The Assemblers
2483 This is retargettable assembler & linkage editor, it was developed by Alan
2485 John Hartman created the version for 8051, and I (Sandeep) have made some
2486 enhancements and bug fixes for it to work properly with the SDCC.
2487 \layout Subsubsection
2492 S51 is a freeware, opensource simulator developed by Daniel Drotos (
2493 \begin_inset LatexCommand \url{mailto:drdani@mazsola.iit.uni-miskolc.hu}
2498 The simulator is built as part of the build process.
2499 For more information visit Daniel's website at:
2500 \begin_inset LatexCommand \url{http://mazsola.iit.uni-miskolc.hu/~drdani/embedded/s51}
2505 It currently support the core mcs51, the Dallas DS80C390 and the Philips
2507 \layout Subsubsection
2509 sdcdb - Source Level Debugger
2515 <todo: is this thing still alive?>
2522 Sdcdb is the companion source level debugger.
2523 The current version of the debugger uses Daniel's Simulator S51, but can
2524 be easily changed to use other simulators.
2531 \layout Subsubsection
2533 Single Source File Projects
2536 For single source file 8051 projects the process is very simple.
2537 Compile your programs with the following command
2540 "sdcc sourcefile.c".
2544 This will compile, assemble and link your source file.
2545 Output files are as follows
2549 sourcefile.asm - Assembler source file created by the compiler
2551 sourcefile.lst - Assembler listing file created by the Assembler
2553 sourcefile.rst - Assembler listing file updated with linkedit information,
2554 created by linkage editor
2556 sourcefile.sym - symbol listing for the sourcefile, created by the assembler
2558 sourcefile.rel - Object file created by the assembler, input to Linkage editor
2560 sourcefile.map - The memory map for the load module, created by the Linker
2562 sourcefile.ihx - The load module in Intel hex format (you can select the
2563 Motorola S19 format with ---out-fmt-s19)
2565 sourcefile.cdb - An optional file (with ---debug) containing debug information
2567 sourcefile.dump* - Dump file to debug the compiler it self (with ---dumpall)
2569 \begin_inset Quotes sld
2572 Anatomy of the compiler
2573 \begin_inset Quotes srd
2577 \layout Subsubsection
2579 Projects with Multiple Source Files
2582 SDCC can compile only ONE file at a time.
2583 Let us for example assume that you have a project containing the following
2588 foo1.c (contains some functions)
2590 foo2.c (contains some more functions)
2592 foomain.c (contains more functions and the function main)
2600 The first two files will need to be compiled separately with the commands:
2632 Then compile the source file containing the
2636 function and link the files together with the following command:
2644 foomain.c\SpecialChar ~
2645 foo1.rel\SpecialChar ~
2657 can be separately compiled as well:
2668 sdcc foomain.rel foo1.rel foo2.rel
2675 The file containing the
2690 file specified in the command line, since the linkage editor processes
2691 file in the order they are presented to it.
2692 \layout Subsubsection
2694 Projects with Additional Libraries
2697 Some reusable routines may be compiled into a library, see the documentation
2698 for the assembler and linkage editor (which are in <installdir>/share/sdcc/doc)
2704 Libraries created in this manner can be included in the command line.
2705 Make sure you include the -L <library-path> option to tell the linker where
2706 to look for these files if they are not in the current directory.
2707 Here is an example, assuming you have the source file
2719 (if that is not the same as your current project):
2726 sdcc foomain.c foolib.lib -L mylib
2737 must be an absolute path name.
2741 The most efficient way to use libraries is to keep seperate modules in seperate
2743 The lib file now should name all the modules.rel files.
2744 For an example see the standard library file
2748 in the directory <installdir>/share/lib/small.
2751 Command Line Options
2752 \layout Subsubsection
2754 Processor Selection Options
2756 \labelwidthstring 00.00.0000
2762 Generate code for the MCS51 (8051) family of processors.
2763 This is the default processor target.
2765 \labelwidthstring 00.00.0000
2771 Generate code for the DS80C390 processor.
2773 \labelwidthstring 00.00.0000
2779 Generate code for the Z80 family of processors.
2781 \labelwidthstring 00.00.0000
2787 Generate code for the GameBoy Z80 processor.
2789 \labelwidthstring 00.00.0000
2795 Generate code for the Atmel AVR processor (In development, not complete).
2797 \labelwidthstring 00.00.0000
2803 Generate code for the PIC 14-bit processors (In development, not complete).
2805 \labelwidthstring 00.00.0000
2811 Generate code for the Toshiba TLCS-900H processor (In development, not
2814 \labelwidthstring 00.00.0000
2820 Generate code for the Philips XA51 processor (In development, not complete).
2821 \layout Subsubsection
2823 Preprocessor Options
2825 \labelwidthstring 00.00.0000
2831 The additional location where the pre processor will look for <..h> or
2832 \begin_inset Quotes eld
2836 \begin_inset Quotes erd
2841 \labelwidthstring 00.00.0000
2847 Command line definition of macros.
2848 Passed to the pre processor.
2850 \labelwidthstring 00.00.0000
2856 Tell the preprocessor to output a rule suitable for make describing the
2857 dependencies of each object file.
2858 For each source file, the preprocessor outputs one make-rule whose target
2859 is the object file name for that source file and whose dependencies are
2860 all the files `#include'd in it.
2861 This rule may be a single line or may be continued with `
2863 '-newline if it is long.
2864 The list of rules is printed on standard output instead of the preprocessed
2868 \labelwidthstring 00.00.0000
2874 Tell the preprocessor not to discard comments.
2875 Used with the `-E' option.
2877 \labelwidthstring 00.00.0000
2888 Like `-M' but the output mentions only the user header files included with
2890 \begin_inset Quotes eld
2894 System header files included with `#include <file>' are omitted.
2896 \labelwidthstring 00.00.0000
2902 Assert the answer answer for question, in case it is tested with a preprocessor
2903 conditional such as `#if #question(answer)'.
2904 `-A-' disables the standard assertions that normally describe the target
2907 \labelwidthstring 00.00.0000
2913 (answer) Assert the answer answer for question, in case it is tested with
2914 a preprocessor conditional such as `#if #question(answer)'.
2915 `-A-' disables the standard assertions that normally describe the target
2918 \labelwidthstring 00.00.0000
2924 Undefine macro macro.
2925 `-U' options are evaluated after all `-D' options, but before any `-include'
2926 and `-imacros' options.
2928 \labelwidthstring 00.00.0000
2934 Tell the preprocessor to output only a list of the macro definitions that
2935 are in effect at the end of preprocessing.
2936 Used with the `-E' option.
2938 \labelwidthstring 00.00.0000
2944 Tell the preprocessor to pass all macro definitions into the output, in
2945 their proper sequence in the rest of the output.
2947 \labelwidthstring 00.00.0000
2958 Like `-dD' except that the macro arguments and contents are omitted.
2959 Only `#define name' is included in the output.
2960 \layout Subsubsection
2964 \labelwidthstring 00.00.0000
2974 <absolute path to additional libraries> This option is passed to the linkage
2975 editor's additional libraries search path.
2976 The path name must be absolute.
2977 Additional library files may be specified in the command line.
2978 See section Compiling programs for more details.
2980 \labelwidthstring 00.00.0000
2986 <Value> The start location of the external ram, default value is 0.
2987 The value entered can be in Hexadecimal or Decimal format, e.g.: ---xram-loc
2988 0x8000 or ---xram-loc 32768.
2990 \labelwidthstring 00.00.0000
2996 <Value> The start location of the code segment, default value 0.
2997 Note when this option is used the interrupt vector table is also relocated
2998 to the given address.
2999 The value entered can be in Hexadecimal or Decimal format, e.g.: ---code-loc
3000 0x8000 or ---code-loc 32768.
3002 \labelwidthstring 00.00.0000
3008 <Value> By default the stack is placed after the data segment.
3009 Using this option the stack can be placed anywhere in the internal memory
3011 The value entered can be in Hexadecimal or Decimal format, e.g.
3012 ---stack-loc 0x20 or ---stack-loc 32.
3013 Since the sp register is incremented before a push or call, the initial
3014 sp will be set to one byte prior the provided value.
3015 The provided value should not overlap any other memory areas such as used
3016 register banks or the data segment and with enough space for the current
3019 \labelwidthstring 00.00.0000
3025 <Value> The start location of the internal ram data segment.
3026 The value entered can be in Hexadecimal or Decimal format, eg.
3027 ---data-loc 0x20 or ---data-loc 32.
3028 (By default, the start location of the internal ram data segment is set
3029 as low as possible in memory, taking into account the used register banks
3030 and the bit segment at address 0x20.
3031 For example if register banks 0 and 1 are used without bit variables, the
3032 data segment will be set, if ---data-loc is not used, to location 0x10.)
3034 \labelwidthstring 00.00.0000
3040 <Value> The start location of the indirectly addressable internal ram, default
3042 The value entered can be in Hexadecimal or Decimal format, eg.
3043 ---idata-loc 0x88 or ---idata-loc 136.
3045 \labelwidthstring 00.00.0000
3054 The linker output (final object code) is in Intel Hex format.
3055 (This is the default option).
3057 \labelwidthstring 00.00.0000
3066 The linker output (final object code) is in Motorola S19 format.
3067 \layout Subsubsection
3071 \labelwidthstring 00.00.0000
3077 Generate code for Large model programs see section Memory Models for more
3079 If this option is used all source files in the project should be compiled
3081 In addition the standard library routines are compiled with small model,
3082 they will need to be recompiled.
3084 \labelwidthstring 00.00.0000
3095 Generate code for Small Model programs see section Memory Models for more
3097 This is the default model.
3098 \layout Subsubsection
3102 \labelwidthstring 00.00.0000
3113 Generate 24-bit flat mode code.
3114 This is the one and only that the ds390 code generator supports right now
3115 and is default when using
3120 See section Memory Models for more details.
3122 \labelwidthstring 00.00.0000
3128 Generate code for the 10 bit stack mode of the Dallas DS80C390 part.
3129 This is the one and only that the ds390 code generator supports right now
3130 and is default when using
3135 In this mode, the stack is located in the lower 1K of the internal RAM,
3136 which is mapped to 0x400000.
3137 Note that the support is incomplete, since it still uses a single byte
3138 as the stack pointer.
3139 This means that only the lower 256 bytes of the potential 1K stack space
3140 will actually be used.
3141 However, this does allow you to reclaim the precious 256 bytes of low RAM
3142 for use for the DATA and IDATA segments.
3143 The compiler will not generate any code to put the processor into 10 bit
3145 It is important to ensure that the processor is in this mode before calling
3146 any re-entrant functions compiled with this option.
3147 In principle, this should work with the
3151 option, but that has not been tested.
3152 It is incompatible with the
3157 It also only makes sense if the processor is in 24 bit contiguous addressing
3160 ---model-flat24 option
3163 \layout Subsubsection
3165 Optimization Options
3167 \labelwidthstring 00.00.0000
3173 Will not do global subexpression elimination, this option may be used when
3174 the compiler creates undesirably large stack/data spaces to store compiler
3176 A warning message will be generated when this happens and the compiler
3177 will indicate the number of extra bytes it allocated.
3178 It recommended that this option NOT be used, #pragma\SpecialChar ~
3180 to turn off global subexpression elimination for a given function only.
3182 \labelwidthstring 00.00.0000
3188 Will not do loop invariant optimizations, this may be turned off for reasons
3189 explained for the previous option.
3190 For more details of loop optimizations performed see section Loop Invariants.It
3191 recommended that this option NOT be used, #pragma\SpecialChar ~
3192 NOINVARIANT can be used
3193 to turn off invariant optimizations for a given function only.
3195 \labelwidthstring 00.00.0000
3201 Will not do loop induction optimizations, see section strength reduction
3202 for more details.It is recommended that this option is NOT used, #pragma\SpecialChar ~
3204 ION can be used to turn off induction optimizations for a given function
3207 \labelwidthstring 00.00.0000
3218 Will not generate boundary condition check when switch statements are implement
3219 ed using jump-tables.
3220 See section Switch Statements for more details.
3221 It is recommended that this option is NOT used, #pragma\SpecialChar ~
3223 used to turn off boundary checking for jump tables for a given function
3226 \labelwidthstring 00.00.0000
3235 Will not do loop reversal optimization.
3237 \labelwidthstring 00.00.0000
3243 Will not optimize labels (makes the dumpfiles more readable).
3245 \labelwidthstring 00.00.0000
3251 Will not memcpy initialized data in far space from code space.
3252 This saves a few bytes in code space if you don't have initialized data.
3253 \layout Subsubsection
3257 \labelwidthstring 00.00.0000
3264 will compile and assemble the source, but will not call the linkage editor.
3266 \labelwidthstring 00.00.0000
3272 reads the preprocessed source from standard input and compiles it.
3273 The file name for the assembler output must be specified using the -o option.
3275 \labelwidthstring 00.00.0000
3281 Run only the C preprocessor.
3282 Preprocess all the C source files specified and output the results to standard
3285 \labelwidthstring 00.00.0000
3292 The output path resp.
3293 file where everything will be placed.
3294 If the parameter is a path, it must have a trailing slash (or backslash
3295 for the Windows binaries) to be recognized as a path.
3298 \labelwidthstring 00.00.0000
3309 All functions in the source file will be compiled as
3314 the parameters and local variables will be allocated on the stack.
3315 see section Parameters and Local Variables for more details.
3316 If this option is used all source files in the project should be compiled
3320 \labelwidthstring 00.00.0000
3326 Uses a pseudo stack in the first 256 bytes in the external ram for allocating
3327 variables and passing parameters.
3328 See section on external stack for more details.
3330 \labelwidthstring 00.00.0000
3334 ---callee-saves function1[,function2][,function3]....
3337 The compiler by default uses a caller saves convention for register saving
3338 across function calls, however this can cause unneccessary register pushing
3339 & popping when calling small functions from larger functions.
3340 This option can be used to switch the register saving convention for the
3341 function names specified.
3342 The compiler will not save registers when calling these functions, no extra
3343 code will be generated at the entry & exit for these functions to save
3344 & restore the registers used by these functions, this can SUBSTANTIALLY
3345 reduce code & improve run time performance of the generated code.
3346 In the future the compiler (with interprocedural analysis) will be able
3347 to determine the appropriate scheme to use for each function call.
3348 DO NOT use this option for built-in functions such as _muluint..., if this
3349 option is used for a library function the appropriate library function
3350 needs to be recompiled with the same option.
3351 If the project consists of multiple source files then all the source file
3352 should be compiled with the same ---callee-saves option string.
3353 Also see #pragma\SpecialChar ~
3356 \labelwidthstring 00.00.0000
3365 When this option is used the compiler will generate debug information, that
3366 can be used with the SDCDB.
3367 The debug information is collected in a file with .cdb extension.
3368 For more information see documentation for SDCDB.
3370 \labelwidthstring 00.00.0000
3376 <filename> This option can be used to use additional rules to be used by
3377 the peep hole optimizer.
3378 See section Peep Hole optimizations for details on how to write these rules.
3380 \labelwidthstring 00.00.0000
3391 Stop after the stage of compilation proper; do not assemble.
3392 The output is an assembler code file for the input file specified.
3394 \labelwidthstring 00.00.0000
3398 -Wa_asmOption[,asmOption]
3401 Pass the asmOption to the assembler.
3403 \labelwidthstring 00.00.0000
3407 -Wl_linkOption[,linkOption]
3410 Pass the linkOption to the linker.
3412 \labelwidthstring 00.00.0000
3421 Integer (16 bit) and long (32 bit) libraries have been compiled as reentrant.
3422 Note by default these libraries are compiled as non-reentrant.
3423 See section Installation for more details.
3425 \labelwidthstring 00.00.0000
3434 This option will cause the compiler to generate an information message for
3435 each function in the source file.
3436 The message contains some
3440 information about the function.
3441 The number of edges and nodes the compiler detected in the control flow
3442 graph of the function, and most importantly the
3444 cyclomatic complexity
3446 see section on Cyclomatic Complexity for more details.
3448 \labelwidthstring 00.00.0000
3457 Floating point library is compiled as reentrant.See section Installation
3460 \labelwidthstring 00.00.0000
3466 The compiler will not overlay parameters and local variables of any function,
3467 see section Parameters and local variables for more details.
3469 \labelwidthstring 00.00.0000
3475 This option can be used when the code generated is called by a monitor
3477 The compiler will generate a 'ret' upon return from the 'main' function.
3478 The default option is to lock up i.e.
3481 \labelwidthstring 00.00.0000
3487 Disable peep-hole optimization.
3489 \labelwidthstring 00.00.0000
3495 Pass the inline assembler code through the peep hole optimizer.
3496 This can cause unexpected changes to inline assembler code, please go through
3497 the peephole optimizer rules defined in the source file tree '<target>/peeph.def
3498 ' before using this option.
3500 \labelwidthstring 00.00.0000
3506 <Value> Causes the linker to check if the internal ram usage is within limits
3509 \labelwidthstring 00.00.0000
3515 <Value> Causes the linker to check if the external ram usage is within limits
3518 \labelwidthstring 00.00.0000
3524 <Value> Causes the linker to check if the code usage is within limits of
3527 \labelwidthstring 00.00.0000
3533 This will prevent the compiler from passing on the default include path
3534 to the preprocessor.
3536 \labelwidthstring 00.00.0000
3542 This will prevent the compiler from passing on the default library path
3545 \labelwidthstring 00.00.0000
3551 Shows the various actions the compiler is performing.
3553 \labelwidthstring 00.00.0000
3559 Shows the actual commands the compiler is executing.
3561 \labelwidthstring 00.00.0000
3567 Hides your ugly and inefficient c-code from the asm file, so you can always
3568 blame the compiler :).
3570 \labelwidthstring 00.00.0000
3576 Include i-codes in the asm file.
3577 Sounds like noise but is most helpfull for debugging the compiler itself.
3579 \labelwidthstring 00.00.0000
3585 Disable some of the more pedantic warnings (jwk burps: please be more specific
3587 \layout Subsubsection
3589 Intermediate Dump Options
3592 The following options are provided for the purpose of retargetting and debugging
3594 These provided a means to dump the intermediate code (iCode) generated
3595 by the compiler in human readable form at various stages of the compilation
3599 \labelwidthstring 00.00.0000
3605 This option will cause the compiler to dump the intermediate code into
3608 <source filename>.dumpraw
3610 just after the intermediate code has been generated for a function, i.e.
3611 before any optimizations are done.
3612 The basic blocks at this stage ordered in the depth first number, so they
3613 may not be in sequence of execution.
3615 \labelwidthstring 00.00.0000
3621 Will create a dump of iCode's, after global subexpression elimination,
3624 <source filename>.dumpgcse.
3626 \labelwidthstring 00.00.0000
3632 Will create a dump of iCode's, after deadcode elimination, into a file
3635 <source filename>.dumpdeadcode.
3637 \labelwidthstring 00.00.0000
3646 Will create a dump of iCode's, after loop optimizations, into a file named
3649 <source filename>.dumploop.
3651 \labelwidthstring 00.00.0000
3660 Will create a dump of iCode's, after live range analysis, into a file named
3663 <source filename>.dumprange.
3665 \labelwidthstring 00.00.0000
3671 Will dump the life ranges for all symbols.
3673 \labelwidthstring 00.00.0000
3682 Will create a dump of iCode's, after register assignment, into a file named
3685 <source filename>.dumprassgn.
3687 \labelwidthstring 00.00.0000
3693 Will create a dump of the live ranges of iTemp's
3695 \labelwidthstring 00.00.0000
3706 Will cause all the above mentioned dumps to be created.
3709 Environment variables
3712 SDCC recognizes the following environment variables:
3714 \labelwidthstring 00.00.0000
3720 SDCC installs a signal handler to be able to delete temporary files after
3721 an user break (^C) or an exception.
3722 If this environment variable is set, SDCC won't install the signal handler
3723 in order to be able to debug SDCC.
3725 \labelwidthstring 00.00.0000
3733 Path, where temporary files will be created.
3734 The order of the variables is the search order.
3735 In a standard *nix environment these variables are not set, and there's
3736 no need to set them.
3737 On Windows it's recommended to set one of them.
3739 \labelwidthstring 00.00.0000
3746 \begin_inset Quotes sld
3749 2.3 Install and search paths
3750 \begin_inset Quotes srd
3755 \labelwidthstring 00.00.0000
3762 \begin_inset Quotes sld
3765 2.3 Install and search paths
3766 \begin_inset Quotes srd
3771 \labelwidthstring 00.00.0000
3778 \begin_inset Quotes sld
3781 2.3 Install and search paths
3782 \begin_inset Quotes srd
3788 There are some more environment variables recognized by SDCC, but these
3789 are solely used for debugging purposes.
3790 They can change or disappear very quickly, and will never be documentated.
3793 MCS51/DS390 Storage Class Language Extensions
3796 In addition to the ANSI storage classes SDCC allows the following MCS51
3797 specific storage classes.
3798 \layout Subsubsection
3803 Variables declared with this storage class will be placed in the extern
3809 storage class for Large Memory model, e.g.:
3815 xdata unsigned char xduc;
3816 \layout Subsubsection
3825 storage class for Small Memory model.
3826 Variables declared with this storage class will be allocated in the internal
3834 \layout Subsubsection
3839 Variables declared with this storage class will be allocated into the indirectly
3840 addressable portion of the internal ram of a 8051, e.g.:
3847 \layout Subsubsection
3852 This is a data-type and a storage class specifier.
3853 When a variable is declared as a bit, it is allocated into the bit addressable
3854 memory of 8051, e.g.:
3861 \layout Subsubsection
3866 Like the bit keyword,
3870 signifies both a data-type and storage class, they are used to describe
3871 the special function registers and special bit variables of a 8051, eg:
3877 sfr at 0x80 P0; /* special function register P0 at location 0x80 */
3879 sbit at 0xd7 CY; /* CY (Carry Flag) */
3885 SDCC allows (via language extensions) pointers to explicitly point to any
3886 of the memory spaces of the 8051.
3887 In addition to the explicit pointers, the compiler uses (by default) generic
3888 pointers which can be used to point to any of the memory spaces.
3892 Pointer declaration examples:
3901 /* pointer physically in xternal ram pointing to object in internal ram
3904 data unsigned char * xdata p;
3908 /* pointer physically in code rom pointing to data in xdata space */
3910 xdata unsigned char * code p;
3914 /* pointer physically in code space pointing to data in code space */
3916 code unsigned char * code p;
3920 /* the folowing is a generic pointer physically located in xdata space */
3931 Well you get the idea.
3936 All unqualified pointers are treated as 3-byte (4-byte for the ds390)
3949 The highest order byte of the
3953 pointers contains the data space information.
3954 Assembler support routines are called whenever data is stored or retrieved
3960 These are useful for developing reusable library routines.
3961 Explicitly specifying the pointer type will generate the most efficient
3965 Parameters & Local Variables
3968 Automatic (local) variables and parameters to functions can either be placed
3969 on the stack or in data-space.
3970 The default action of the compiler is to place these variables in the internal
3971 RAM (for small model) or external RAM (for large model).
3972 This in fact makes them
3976 so by default functions are non-reentrant.
3980 They can be placed on the stack either by using the
3984 option or by using the
3988 keyword in the function declaration, e.g.:
3997 unsigned char foo(char i) reentrant
4010 Since stack space on 8051 is limited, the
4018 option should be used sparingly.
4019 Note that the reentrant keyword just means that the parameters & local
4020 variables will be allocated to the stack, it
4024 mean that the function is register bank independent.
4028 Local variables can be assigned storage classes and absolute addresses,
4035 unsigned char foo() {
4041 xdata unsigned char i;
4053 data at 0x31 unsiged char j;
4068 In the above example the variable
4072 will be allocated in the external ram,
4076 in bit addressable space and
4085 or when a function is declared as
4089 this should only be done for static variables.
4092 Parameters however are not allowed any storage class, (storage classes for
4093 parameters will be ignored), their allocation is governed by the memory
4094 model in use, and the reentrancy options.
4100 For non-reentrant functions SDCC will try to reduce internal ram space usage
4101 by overlaying parameters and local variables of a function (if possible).
4102 Parameters and local variables of a function will be allocated to an overlayabl
4103 e segment if the function has
4105 no other function calls and the function is non-reentrant and the memory
4109 If an explicit storage class is specified for a local variable, it will
4113 Note that the compiler (not the linkage editor) makes the decision for overlayin
4115 Functions that are called from an interrupt service routine should be preceded
4116 by a #pragma\SpecialChar ~
4117 NOOVERLAY if they are not reentrant.
4120 Also note that the compiler does not do any processing of inline assembler
4121 code, so the compiler might incorrectly assign local variables and parameters
4122 of a function into the overlay segment if the inline assembler code calls
4123 other c-functions that might use the overlay.
4124 In that case the #pragma\SpecialChar ~
4125 NOOVERLAY should be used.
4128 Parameters and Local variables of functions that contain 16 or 32 bit multiplica
4129 tion or division will NOT be overlayed since these are implemented using
4130 external functions, e.g.:
4140 void set_error(unsigned char errcd)
4156 void some_isr () interrupt 2 using 1
4185 In the above example the parameter
4193 would be assigned to the overlayable segment if the #pragma\SpecialChar ~
4195 not present, this could cause unpredictable runtime behavior when called
4197 The #pragma\SpecialChar ~
4198 NOOVERLAY ensures that the parameters and local variables for
4199 the function are NOT overlayed.
4202 Interrupt Service Routines
4205 SDCC allows interrupt service routines to be coded in C, with some extended
4212 void timer_isr (void) interrupt 2 using 1
4225 The number following the
4229 keyword is the interrupt number this routine will service.
4230 The compiler will insert a call to this routine in the interrupt vector
4231 table for the interrupt number specified.
4236 keyword is used to tell the compiler to use the specified register bank
4237 (8051 specific) when generating code for this function.
4238 Note that when some function is called from an interrupt service routine
4239 it should be preceded by a #pragma\SpecialChar ~
4240 NOOVERLAY if it is not reentrant.
4241 A special note here, int (16 bit) and long (32 bit) integer division, multiplic
4242 ation & modulus operations are implemented using external support routines
4243 developed in ANSI-C, if an interrupt service routine needs to do any of
4244 these operations then the support routines (as mentioned in a following
4245 section) will have to be recompiled using the
4249 option and the source file will need to be compiled using the
4256 If you have multiple source files in your project, interrupt service routines
4257 can be present in any of them, but a prototype of the isr MUST be present
4258 or included in the file that contains the function
4265 Interrupt Numbers and the corresponding address & descriptions for the Standard
4266 8051 are listed below.
4267 SDCC will automatically adjust the interrupt vector table to the maximum
4268 interrupt number specified.
4274 \begin_inset Tabular
4275 <lyxtabular version="3" rows="6" columns="3">
4277 <column alignment="center" valignment="top" leftline="true" width="0in">
4278 <column alignment="center" valignment="top" leftline="true" width="0in">
4279 <column alignment="center" valignment="top" leftline="true" rightline="true" width="0in">
4280 <row topline="true" bottomline="true">
4281 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
4289 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
4297 <cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
4306 <row topline="true">
4307 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
4315 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
4323 <cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
4332 <row topline="true">
4333 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
4341 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
4349 <cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
4358 <row topline="true">
4359 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
4367 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
4375 <cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
4384 <row topline="true">
4385 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
4393 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
4401 <cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
4410 <row topline="true" bottomline="true">
4411 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
4419 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
4427 <cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
4444 If the interrupt service routine is defined without
4448 a register bank or with register bank 0 (using 0), the compiler will save
4449 the registers used by itself on the stack upon entry and restore them at
4450 exit, however if such an interrupt service routine calls another function
4451 then the entire register bank will be saved on the stack.
4452 This scheme may be advantageous for small interrupt service routines which
4453 have low register usage.
4456 If the interrupt service routine is defined to be using a specific register
4461 are save and restored, if such an interrupt service routine calls another
4462 function (using another register bank) then the entire register bank of
4463 the called function will be saved on the stack.
4464 This scheme is recommended for larger interrupt service routines.
4467 Calling other functions from an interrupt service routine is not recommended,
4468 avoid it if possible.
4472 Also see the _naked modifier.
4480 <TODO: this isn't implemented at all!>
4486 A special keyword may be associated with a function declaring it as
4491 SDCC will generate code to disable all interrupts upon entry to a critical
4492 function and enable them back before returning.
4493 Note that nesting critical functions may cause unpredictable results.
4518 The critical attribute maybe used with other attributes like
4526 A special keyword may be associated with a function declaring it as
4535 function modifier attribute prevents the compiler from generating prologue
4536 and epilogue code for that function.
4537 This means that the user is entirely responsible for such things as saving
4538 any registers that may need to be preserved, selecting the proper register
4539 bank, generating the
4543 instruction at the end, etc.
4544 Practically, this means that the contents of the function must be written
4545 in inline assembler.
4546 This is particularly useful for interrupt functions, which can have a large
4547 (and often unnecessary) prologue/epilogue.
4548 For example, compare the code generated by these two functions:
4554 data unsigned char counter;
4556 void simpleInterrupt(void) interrupt 1
4570 void nakedInterrupt(void) interrupt 2 _naked
4603 ; MUST explicitly include ret in _naked function.
4617 For an 8051 target, the generated simpleInterrupt looks like:
4762 whereas nakedInterrupt looks like:
4787 ; MUST explicitly include ret(i) in _naked function.
4793 While there is nothing preventing you from writing C code inside a _naked
4794 function, there are many ways to shoot yourself in the foot doing this,
4795 and it is recommended that you stick to inline assembler.
4798 Functions using private banks
4805 attribute (which tells the compiler to use a register bank other than the
4806 default bank zero) should only be applied to
4810 functions (see note 1 below).
4811 This will in most circumstances make the generated ISR code more efficient
4812 since it will not have to save registers on the stack.
4819 attribute will have no effect on the generated code for a
4823 function (but may occasionally be useful anyway
4829 possible exception: if a function is called ONLY from 'interrupt' functions
4830 using a particular bank, it can be declared with the same 'using' attribute
4831 as the calling 'interrupt' functions.
4832 For instance, if you have several ISRs using bank one, and all of them
4833 call memcpy(), it might make sense to create a specialized version of memcpy()
4834 'using 1', since this would prevent the ISR from having to save bank zero
4835 to the stack on entry and switch to bank zero before calling the function
4842 (pending: I don't think this has been done yet)
4849 function using a non-zero bank will assume that it can trash that register
4850 bank, and will not save it.
4851 Since high-priority interrupts can interrupt low-priority ones on the 8051
4852 and friends, this means that if a high-priority ISR
4856 a particular bank occurs while processing a low-priority ISR
4860 the same bank, terrible and bad things can happen.
4861 To prevent this, no single register bank should be
4865 by both a high priority and a low priority ISR.
4866 This is probably most easily done by having all high priority ISRs use
4867 one bank and all low priority ISRs use another.
4868 If you have an ISR which can change priority at runtime, you're on your
4869 own: I suggest using the default bank zero and taking the small performance
4873 It is most efficient if your ISR calls no other functions.
4874 If your ISR must call other functions, it is most efficient if those functions
4875 use the same bank as the ISR (see note 1 below); the next best is if the
4876 called functions use bank zero.
4877 It is very inefficient to call a function using a different, non-zero bank
4885 Data items can be assigned an absolute address with the
4889 keyword, in addition to a storage class, e.g.:
4895 xdata at 0x8000 unsigned char PORTA_8255 ;
4901 In the above example the PORTA_8255 will be allocated to the location 0x8000
4902 of the external ram.
4903 Note that this feature is provided to give the programmer access to
4907 devices attached to the controller.
4908 The compiler does not actually reserve any space for variables declared
4909 in this way (they are implemented with an equate in the assembler).
4910 Thus it is left to the programmer to make sure there are no overlaps with
4911 other variables that are declared without the absolute address.
4912 The assembler listing file (.lst) and the linker output files (.rst) and
4913 (.map) are a good places to look for such overlaps.
4917 Absolute address can be specified for variables in all storage classes,
4930 The above example will allocate the variable at offset 0x02 in the bit-addressab
4932 There is no real advantage to assigning absolute addresses to variables
4933 in this manner, unless you want strict control over all the variables allocated.
4939 The compiler inserts a call to the C routine
4941 _sdcc__external__startup()
4946 at the start of the CODE area.
4947 This routine is in the runtime library.
4948 By default this routine returns 0, if this routine returns a non-zero value,
4949 the static & global variable initialization will be skipped and the function
4950 main will be invoked Other wise static & global variables will be initialized
4951 before the function main is invoked.
4954 _sdcc__external__startup()
4956 routine to your program to override the default if you need to setup hardware
4957 or perform some other critical operation prior to static & global variable
4961 Inline Assembler Code
4964 SDCC allows the use of in-line assembler with a few restriction as regards
4966 All labels defined within inline assembler code
4974 where nnnn is a number less than 100 (which implies a limit of utmost 100
4975 inline assembler labels
4983 It is strongly recommended that each assembly instruction (including labels)
4984 be placed in a separate line (as the example shows).
4989 command line option is used, the inline assembler code will be passed through
4990 the peephole optimizer.
4991 This might cause some unexpected changes in the inline assembler code.
4992 Please go throught the peephole optimizer rules defined in file
4996 carefully before using this option.
5036 The inline assembler code can contain any valid code understood by the assembler
5037 , this includes any assembler directives and comment lines.
5038 The compiler does not do any validation of the code within the
5048 Inline assembler code cannot reference any C-Labels, however it can reference
5049 labels defined by the inline assembler, e.g.:
5075 ; some assembler code
5095 /* some more c code */
5097 clabel:\SpecialChar ~
5099 /* inline assembler cannot reference this label */
5111 $0003: ;label (can be reference by inline assembler only)
5123 /* some more c code */
5131 In other words inline assembly code can access labels defined in inline
5132 assembly within the scope of the funtion.
5136 The same goes the other way, ie.
5137 labels defines in inline assembly CANNOT be accessed by C statements.
5140 int (16 bit) and long (32 bit) Support
5143 For signed & unsigned int (16 bit) and long (32 bit) variables, division,
5144 multiplication and modulus operations are implemented by support routines.
5145 These support routines are all developed in ANSI-C to facilitate porting
5146 to other MCUs, although some model specific assembler optimations are used.
5147 The following files contain the described routine, all of them can be found
5148 in <installdir>/share/sdcc/lib.
5154 <pending: tabularise this>
5160 _mulsint.c - signed 16 bit multiplication (calls _muluint)
5162 _muluint.c - unsigned 16 bit multiplication
5164 _divsint.c - signed 16 bit division (calls _divuint)
5166 _divuint.c - unsigned 16 bit division
5168 _modsint.c - signed 16 bit modulus (call _moduint)
5170 _moduint.c - unsigned 16 bit modulus
5172 _mulslong.c - signed 32 bit multiplication (calls _mululong)
5174 _mululong.c - unsigned32 bit multiplication
5176 _divslong.c - signed 32 division (calls _divulong)
5178 _divulong.c - unsigned 32 division
5180 _modslong.c - signed 32 bit modulus (calls _modulong)
5182 _modulong.c - unsigned 32 bit modulus
5190 Since they are compiled as
5194 , interrupt service routines should not do any of the above operations.
5195 If this is unavoidable then the above routines will need to be compiled
5200 option, after which the source program will have to be compiled with
5207 Floating Point Support
5210 SDCC supports IEEE (single precision 4bytes) floating point numbers.The floating
5211 point support routines are derived from gcc's floatlib.c and consists of
5212 the following routines:
5218 <pending: tabularise this>
5224 _fsadd.c - add floating point numbers
5226 _fssub.c - subtract floating point numbers
5228 _fsdiv.c - divide floating point numbers
5230 _fsmul.c - multiply floating point numbers
5232 _fs2uchar.c - convert floating point to unsigned char
5234 _fs2char.c - convert floating point to signed char
5236 _fs2uint.c - convert floating point to unsigned int
5238 _fs2int.c - convert floating point to signed int
5240 _fs2ulong.c - convert floating point to unsigned long
5242 _fs2long.c - convert floating point to signed long
5244 _uchar2fs.c - convert unsigned char to floating point
5246 _char2fs.c - convert char to floating point number
5248 _uint2fs.c - convert unsigned int to floating point
5250 _int2fs.c - convert int to floating point numbers
5252 _ulong2fs.c - convert unsigned long to floating point number
5254 _long2fs.c - convert long to floating point number
5262 Note if all these routines are used simultaneously the data space might
5264 For serious floating point usage it is strongly recommended that the large
5271 SDCC allows two memory models for MCS51 code, small and large.
5272 Modules compiled with different memory models should
5276 be combined together or the results would be unpredictable.
5277 The library routines supplied with the compiler are compiled as both small
5279 The compiled library modules are contained in seperate directories as small
5280 and large so that you can link to either set.
5284 When the large model is used all variables declared without a storage class
5285 will be allocated into the external ram, this includes all parameters and
5286 local variables (for non-reentrant functions).
5287 When the small model is used variables without storage class are allocated
5288 in the internal ram.
5291 Judicious usage of the processor specific storage classes and the 'reentrant'
5292 function type will yield much more efficient code, than using the large
5294 Several optimizations are disabled when the program is compiled using the
5295 large model, it is therefore strongly recommdended that the small model
5296 be used unless absolutely required.
5302 The only model supported is Flat 24.
5303 This generates code for the 24 bit contiguous addressing mode of the Dallas
5305 In this mode, up to four meg of external RAM or code space can be directly
5307 See the data sheets at www.dalsemi.com for further information on this part.
5311 In older versions of the compiler, this option was used with the MCS51 code
5317 Now, however, the '390 has it's own code generator, selected by the
5326 Note that the compiler does not generate any code to place the processor
5327 into 24 bitmode (although
5331 in the ds390 libraries will do that for you).
5336 , the boot loader or similar code must ensure that the processor is in 24
5337 bit contiguous addressing mode before calling the SDCC startup code.
5345 option, variables will by default be placed into the XDATA segment.
5350 Segments may be placed anywhere in the 4 meg address space using the usual
5352 Note that if any segments are located above 64K, the -r flag must be passed
5353 to the linker to generate the proper segment relocations, and the Intel
5354 HEX output format must be used.
5355 The -r flag can be passed to the linker by using the option
5359 on the sdcc command line.
5360 However, currently the linker can not handle code segments > 64k.
5363 Defines Created by the Compiler
5366 The compiler creates the following #defines.
5369 SDCC - this Symbol is always defined.
5372 SDCC_mcs51 or SDCC_ds390 or SDCC_z80, etc - depending on the model used
5376 __mcs51 or __ds390 or __z80, etc - depending on the model used (e.g.
5380 SDCC_STACK_AUTO - this symbol is defined when
5387 SDCC_MODEL_SMALL - when
5394 SDCC_MODEL_LARGE - when
5401 SDCC_USE_XSTACK - when
5408 SDCC_STACK_TENBIT - when
5415 SDCC_MODEL_FLAT24 - when
5428 SDCC performs a host of standard optimizations in addition to some MCU specific
5431 \layout Subsubsection
5433 Sub-expression Elimination
5436 The compiler does local and global common subexpression elimination, e.g.:
5451 will be translated to
5467 Some subexpressions are not as obvious as the above example, e.g.:
5481 In this case the address arithmetic a->b[i] will be computed only once;
5482 the equivalent code in C would be.
5498 The compiler will try to keep these temporary variables in registers.
5499 \layout Subsubsection
5501 Dead-Code Elimination
5516 i = 1; \SpecialChar ~
5521 global = 1;\SpecialChar ~
5534 global = 3;\SpecialChar ~
5549 int global; void f ()
5562 \layout Subsubsection
5623 Note: the dead stores created by this copy propagation will be eliminated
5624 by dead-code elimination.
5625 \layout Subsubsection
5630 Two types of loop optimizations are done by SDCC loop invariant lifting
5631 and strength reduction of loop induction variables.
5632 In addition to the strength reduction the optimizer marks the induction
5633 variables and the register allocator tries to keep the induction variables
5634 in registers for the duration of the loop.
5635 Because of this preference of the register allocator, loop induction optimizati
5636 on causes an increase in register pressure, which may cause unwanted spilling
5637 of other temporary variables into the stack / data space.
5638 The compiler will generate a warning message when it is forced to allocate
5639 extra space either on the stack or data space.
5640 If this extra space allocation is undesirable then induction optimization
5641 can be eliminated either for the entire source file (with ---noinduction
5642 option) or for a given function only using #pragma\SpecialChar ~
5653 for (i = 0 ; i < 100 ; i ++)
5671 for (i = 0; i < 100; i++)
5681 As mentioned previously some loop invariants are not as apparent, all static
5682 address computations are also moved out of the loop.
5686 Strength Reduction, this optimization substitutes an expression by a cheaper
5693 for (i=0;i < 100; i++)
5713 for (i=0;i< 100;i++) {
5717 ar[itemp1] = itemp2;
5733 The more expensive multiplication is changed to a less expensive addition.
5734 \layout Subsubsection
5739 This optimization is done to reduce the overhead of checking loop boundaries
5740 for every iteration.
5741 Some simple loops can be reversed and implemented using a
5742 \begin_inset Quotes eld
5745 decrement and jump if not zero
5746 \begin_inset Quotes erd
5750 SDCC checks for the following criterion to determine if a loop is reversible
5751 (note: more sophisticated compilers use data-dependency analysis to make
5752 this determination, SDCC uses a more simple minded analysis).
5755 The 'for' loop is of the form
5761 for (<symbol> = <expression> ; <sym> [< | <=] <expression> ; [<sym>++ |
5771 The <for body> does not contain
5772 \begin_inset Quotes eld
5776 \begin_inset Quotes erd
5780 \begin_inset Quotes erd
5786 All goto's are contained within the loop.
5789 No function calls within the loop.
5792 The loop control variable <sym> is not assigned any value within the loop
5795 The loop control variable does NOT participate in any arithmetic operation
5799 There are NO switch statements in the loop.
5800 \layout Subsubsection
5802 Algebraic Simplifications
5805 SDCC does numerous algebraic simplifications, the following is a small sub-set
5806 of these optimizations.
5812 i = j + 0 ; /* changed to */ i = j;
5814 i /= 2; /* changed to */ i >>= 1;
5816 i = j - j ; /* changed to */ i = 0;
5818 i = j / 1 ; /* changed to */ i = j;
5824 Note the subexpressions given above are generally introduced by macro expansions
5825 or as a result of copy/constant propagation.
5826 \layout Subsubsection
5831 SDCC changes switch statements to jump tables when the following conditions
5836 The case labels are in numerical sequence, the labels need not be in order,
5837 and the starting number need not be one or zero.
5843 switch(i) {\SpecialChar ~
5950 Both the above switch statements will be implemented using a jump-table.
5953 The number of case labels is at least three, since it takes two conditional
5954 statements to handle the boundary conditions.
5957 The number of case labels is less than 84, since each label takes 3 bytes
5958 and a jump-table can be utmost 256 bytes long.
5962 Switch statements which have gaps in the numeric sequence or those that
5963 have more that 84 case labels can be split into more than one switch statement
5964 for efficient code generation, e.g.:
6002 If the above switch statement is broken down into two switch statements
6036 case 9: \SpecialChar ~
6046 case 12:\SpecialChar ~
6056 then both the switch statements will be implemented using jump-tables whereas
6057 the unmodified switch statement will not be.
6058 \layout Subsubsection
6060 Bit-shifting Operations.
6063 Bit shifting is one of the most frequently used operation in embedded programmin
6065 SDCC tries to implement bit-shift operations in the most efficient way
6085 generates the following code:
6103 In general SDCC will never setup a loop if the shift count is known.
6143 Note that SDCC stores numbers in little-endian format (i.e.
6144 lowest order first).
6145 \layout Subsubsection
6150 A special case of the bit-shift operation is bit rotation, SDCC recognizes
6151 the following expression to be a left bit-rotation:
6162 i = ((i << 1) | (i >> 7));
6170 will generate the following code:
6186 SDCC uses pattern matching on the parse tree to determine this operation.Variatio
6187 ns of this case will also be recognized as bit-rotation, i.e.:
6193 i = ((i >> 7) | (i << 1)); /* left-bit rotation */
6194 \layout Subsubsection
6199 It is frequently required to obtain the highest order bit of an integral
6200 type (long, int, short or char types).
6201 SDCC recognizes the following expression to yield the highest order bit
6202 and generates optimized code for it, e.g.:
6223 hob = (gint >> 15) & 1;
6236 will generate the following code:
6275 000A E5*01\SpecialChar ~
6303 000C 33\SpecialChar ~
6334 000D E4\SpecialChar ~
6365 000E 13\SpecialChar ~
6396 000F F5*02\SpecialChar ~
6426 Variations of this case however will
6431 It is a standard C expression, so I heartily recommend this be the only
6432 way to get the highest order bit, (it is portable).
6433 Of course it will be recognized even if it is embedded in other expressions,
6440 xyz = gint + ((gint >> 15) & 1);
6446 will still be recognized.
6447 \layout Subsubsection
6452 The compiler uses a rule based, pattern matching and re-writing mechanism
6453 for peep-hole optimization.
6458 a peep-hole optimizer by Christopher W.
6459 Fraser (cwfraser@microsoft.com).
6460 A default set of rules are compiled into the compiler, additional rules
6461 may be added with the
6463 ---peep-file <filename>
6466 The rule language is best illustrated with examples.
6494 The above rule will change the following assembly sequence:
6524 Note: All occurrences of a
6528 (pattern variable) must denote the same string.
6529 With the above rule, the assembly sequence:
6547 will remain unmodified.
6551 Other special case optimizations may be added by the user (via
6557 some variants of the 8051 MCU allow only
6566 The following two rules will change all
6588 replace { lcall %1 } by { acall %1 }
6590 replace { ljmp %1 } by { ajmp %1 }
6598 inline-assembler code
6600 is also passed through the peep hole optimizer, thus the peephole optimizer
6601 can also be used as an assembly level macro expander.
6602 The rules themselves are MCU dependent whereas the rule language infra-structur
6603 e is MCU independent.
6604 Peephole optimization rules for other MCU can be easily programmed using
6609 The syntax for a rule is as follows:
6615 rule := replace [ restart ] '{' <assembly sequence> '
6653 <assembly sequence> '
6671 '}' [if <functionName> ] '
6679 <assembly sequence> := assembly instruction (each instruction including
6680 labels must be on a separate line).
6684 The optimizer will apply to the rules one by one from the top in the sequence
6685 of their appearance, it will terminate when all rules are exhausted.
6686 If the 'restart' option is specified, then the optimizer will start matching
6687 the rules again from the top, this option for a rule is expensive (performance)
6688 , it is intended to be used in situations where a transformation will trigger
6689 the same rule again.
6690 An example of this (not a good one, it has side effects) is the following
6717 Note that the replace pattern cannot be a blank, but can be a comment line.
6718 Without the 'restart' option only the inner most 'pop' 'push' pair would
6719 be eliminated, i.e.:
6771 the restart option the rule will be applied again to the resulting code
6772 and then all the pop-push pairs will be eliminated to yield:
6790 A conditional function can be attached to a rule.
6791 Attaching rules are somewhat more involved, let me illustrate this with
6822 The optimizer does a look-up of a function name table defined in function
6827 in the source file SDCCpeeph.c, with the name
6832 If it finds a corresponding entry the function is called.
6833 Note there can be no parameters specified for these functions, in this
6838 is crucial, since the function
6842 expects to find the label in that particular variable (the hash table containin
6843 g the variable bindings is passed as a parameter).
6844 If you want to code more such functions, take a close look at the function
6845 labelInRange and the calling mechanism in source file SDCCpeeph.c.
6846 I know this whole thing is a little kludgey, but maybe some day we will
6847 have some better means.
6848 If you are looking at this file, you will also see the default rules that
6849 are compiled into the compiler, you can add your own rules in the default
6850 set there if you get tired of specifying the ---peep-file option.
6856 SDCC supports the following #pragma directives.
6859 SAVE - this will save all the current options.
6862 RESTORE - will restore the saved options from the last save.
6863 Note that SAVEs & RESTOREs cannot be nested.
6864 SDCC uses the same buffer to save the options each time a SAVE is called.
6865 (jwk burps: either fix that or throw a warning)
6868 NOGCSE - will stop global subexpression elimination.
6871 NOINDUCTION - will stop loop induction optimizations.
6874 NOJTBOUND - will not generate code for boundary value checking, when switch
6875 statements are turned into jump-tables.
6878 NOOVERLAY - the compiler will not overlay the parameters and local variables
6882 LESS_PEDANTIC - the compiler will not warn you anymore for obvious mistakes,
6883 you'r on your own now ;-(
6886 NOLOOPREVERSE - Will not do loop reversal optimization
6889 EXCLUDE NONE | {acc[,b[,dpl[,dph]]] - The exclude pragma disables generation
6890 of pair of push/pop instruction in ISR function (using interrupt keyword).
6891 The directive should be placed immediately before the ISR function definition
6892 and it affects ALL ISR functions following it.
6893 To enable the normal register saving for ISR functions use #pragma\SpecialChar ~
6894 EXCLUDE\SpecialChar ~
6898 NOIV - Do not generate interrupt vector table entries for all ISR functions
6899 defined after the pragma.
6900 This is useful in cases where the interrupt vector table must be defined
6901 manually, or when there is a secondary, manually defined interrupt vector
6903 for the autovector feature of the Cypress EZ-USB FX2).
6906 CALLEE-SAVES function1[,function2[,function3...]] - The compiler by default
6907 uses a caller saves convention for register saving across function calls,
6908 however this can cause unneccessary register pushing & popping when calling
6909 small functions from larger functions.
6910 This option can be used to switch the register saving convention for the
6911 function names specified.
6912 The compiler will not save registers when calling these functions, extra
6913 code will be generated at the entry & exit for these functions to save
6914 & restore the registers used by these functions, this can SUBSTANTIALLY
6915 reduce code & improve run time performance of the generated code.
6916 In future the compiler (with interprocedural analysis) will be able to
6917 determine the appropriate scheme to use for each function call.
6918 If ---callee-saves command line option is used, the function names specified
6919 in #pragma\SpecialChar ~
6920 CALLEE-SAVES is appended to the list of functions specified inthe
6924 The pragma's are intended to be used to turn-off certain optimizations which
6925 might cause the compiler to generate extra stack / data space to store
6926 compiler generated temporary variables.
6927 This usually happens in large functions.
6928 Pragma directives should be used as shown in the following example, they
6929 are used to control options & optimizations for a given function; pragmas
6930 should be placed before and/or after a function, placing pragma's inside
6931 a function body could have unpredictable results.
6937 #pragma SAVE /* save the current settings */
6939 #pragma NOGCSE /* turnoff global subexpression elimination */
6941 #pragma NOINDUCTION /* turn off induction optimizations */
6963 #pragma RESTORE /* turn the optimizations back on */
6969 The compiler will generate a warning message when extra space is allocated.
6970 It is strongly recommended that the SAVE and RESTORE pragma's be used when
6971 changing options for a function.
6976 <pending: this is messy and incomplete>
6981 Compiler support routines (_gptrget, _mulint etc)
6984 Stdclib functions (puts, printf, strcat etc)
6987 Math functions (sin, pow, sqrt etc)
6990 Interfacing with Assembly Routines
6991 \layout Subsubsection
6993 Global Registers used for Parameter Passing
6996 The compiler always uses the global registers
7004 to pass the first parameter to a routine.
7005 The second parameter onwards is either allocated on the stack (for reentrant
7006 routines or if ---stack-auto is used) or in the internal / external ram
7007 (depending on the memory model).
7009 \layout Subsubsection
7011 Assembler Routine(non-reentrant)
7014 In the following example the function cfunc calls an assembler routine asm_func,
7015 which takes two parameters.
7021 extern int asm_func(unsigned char, unsigned char);
7025 int c_func (unsigned char i, unsigned char j)
7033 return asm_func(i,j);
7047 return c_func(10,9);
7055 The corresponding assembler function is:
7061 .globl _asm_func_PARM_2
7125 add a,_asm_func_PARM_2
7161 Note here that the return values are placed in 'dpl' - One byte return value,
7162 'dpl' LSB & 'dph' MSB for two byte values.
7163 'dpl', 'dph' and 'b' for three byte values (generic pointers) and 'dpl','dph','
7164 b' & 'acc' for four byte values.
7167 The parameter naming convention is _<function_name>_PARM_<n>, where n is
7168 the parameter number starting from 1, and counting from the left.
7169 The first parameter is passed in
7170 \begin_inset Quotes eld
7174 \begin_inset Quotes erd
7177 for One bye parameter,
7178 \begin_inset Quotes eld
7182 \begin_inset Quotes erd
7186 \begin_inset Quotes eld
7190 \begin_inset Quotes erd
7194 \begin_inset Quotes eld
7198 \begin_inset Quotes erd
7201 for four bytes, the varible name for the second parameter will be _<function_na
7206 Assemble the assembler routine with the following command:
7213 asx8051 -losg asmfunc.asm
7220 Then compile and link the assembler routine to the C source file with the
7228 sdcc cfunc.c asmfunc.rel
7229 \layout Subsubsection
7231 Assembler Routine(reentrant)
7234 In this case the second parameter onwards will be passed on the stack, the
7235 parameters are pushed from right to left i.e.
7236 after the call the left most parameter will be on the top of the stack.
7243 extern int asm_func(unsigned char, unsigned char);
7247 int c_func (unsigned char i, unsigned char j) reentrant
7255 return asm_func(i,j);
7269 return c_func(10,9);
7277 The corresponding assembler routine is:
7387 The compiling and linking procedure remains the same, however note the extra
7388 entry & exit linkage required for the assembler code, _bp is the stack
7389 frame pointer and is used to compute the offset into the stack for parameters
7390 and local variables.
7396 The external stack is located at the start of the external ram segment,
7397 and is 256 bytes in size.
7398 When ---xstack option is used to compile the program, the parameters and
7399 local variables of all reentrant functions are allocated in this area.
7400 This option is provided for programs with large stack space requirements.
7401 When used with the ---stack-auto option, all parameters and local variables
7402 are allocated on the external stack (note support libraries will need to
7403 be recompiled with the same options).
7406 The compiler outputs the higher order address byte of the external ram segment
7407 into PORT P2, therefore when using the External Stack option, this port
7408 MAY NOT be used by the application program.
7414 Deviations from the compliancy.
7417 functions are not always reentrant.
7420 structures cannot be assigned values directly, cannot be passed as function
7421 parameters or assigned to each other and cannot be a return value from
7448 s1 = s2 ; /* is invalid in SDCC although allowed in ANSI */
7459 struct s foo1 (struct s parms) /* is invalid in SDCC although allowed in
7481 return rets;/* is invalid in SDCC although allowed in ANSI */
7486 'long long' (64 bit integers) not supported.
7489 'double' precision floating point not supported.
7492 No support for setjmp and longjmp (for now).
7495 Old K&R style function declarations are NOT allowed.
7501 foo(i,j) /* this old style of function declarations */
7503 int i,j; /* are valid in ANSI but not valid in SDCC */
7517 functions declared as pointers must be dereferenced during the call.
7528 /* has to be called like this */
7530 (*foo)(); /* ansi standard allows calls to be made like 'foo()' */
7533 Cyclomatic Complexity
7536 Cyclomatic complexity of a function is defined as the number of independent
7537 paths the program can take during execution of the function.
7538 This is an important number since it defines the number test cases you
7539 have to generate to validate the function.
7540 The accepted industry standard for complexity number is 10, if the cyclomatic
7541 complexity reported by SDCC exceeds 10 you should think about simplification
7542 of the function logic.
7543 Note that the complexity level is not related to the number of lines of
7545 Large functions can have low complexity, and small functions can have large
7551 SDCC uses the following formula to compute the complexity:
7556 complexity = (number of edges in control flow graph) - (number of nodes
7557 in control flow graph) + 2;
7561 Having said that the industry standard is 10, you should be aware that in
7562 some cases it be may unavoidable to have a complexity level of less than
7564 For example if you have switch statement with more than 10 case labels,
7565 each case label adds one to the complexity level.
7566 The complexity level is by no means an absolute measure of the algorithmic
7567 complexity of the function, it does however provide a good starting point
7568 for which functions you might look at for further optimization.
7574 Here are a few guidelines that will help the compiler generate more efficient
7575 code, some of the tips are specific to this compiler others are generally
7576 good programming practice.
7579 Use the smallest data type to represent your data-value.
7580 If it is known in advance that the value is going to be less than 256 then
7581 use an 'unsigned char' instead of a 'short' or 'int'.
7584 Use unsigned when it is known in advance that the value is not going to
7586 This helps especially if you are doing division or multiplication.
7589 NEVER jump into a LOOP.
7592 Declare the variables to be local whenever possible, especially loop control
7593 variables (induction).
7596 Since the compiler does not always do implicit integral promotion, the programme
7597 r should do an explicit cast when integral promotion is required.
7600 Reducing the size of division, multiplication & modulus operations can reduce
7601 code size substantially.
7602 Take the following code for example.
7608 foobar(unsigned int p1, unsigned char ch)
7612 unsigned char ch1 = p1 % ch ;
7623 For the modulus operation the variable ch will be promoted to unsigned int
7624 first then the modulus operation will be performed (this will lead to a
7625 call to support routine _moduint()), and the result will be casted to a
7627 If the code is changed to
7633 foobar(unsigned int p1, unsigned char ch)
7637 unsigned char ch1 = (unsigned char)p1 % ch ;
7648 It would substantially reduce the code generated (future versions of the
7649 compiler will be smart enough to detect such optimization oppurtunities).
7652 Notes on MCS51 memory layout
7655 The 8051 family of micro controller have a minimum of 128 bytes of internal
7656 memory which is structured as follows
7660 - Bytes 00-1F - 32 bytes to hold up to 4 banks of the registers R7 to R7
7663 - Bytes 20-2F - 16 bytes to hold 128 bit variables and
7665 - Bytes 30-7F - 60 bytes for general purpose use.
7669 Normally the SDCC compiler will only utilise the first bank of registers,
7670 but it is possible to specify that other banks of registers should be used
7671 in interrupt routines.
7672 By default, the compiler will place the stack after the last bank of used
7674 if the first 2 banks of registers are used, it will position the base of
7675 the internal stack at address 16 (0X10).
7676 This implies that as the stack grows, it will use up the remaining register
7677 banks, and the 16 bytes used by the 128 bit variables, and 60 bytes for
7678 general purpose use.
7681 By default, the compiler uses the 60 general purpose bytes to hold "near
7683 The compiler/optimiser may also declare some Local Variables in this area
7688 If any of the 128 bit variables are used, or near data is being used then
7689 care needs to be taken to ensure that the stack does not grow so much that
7690 it starts to over write either your bit variables or "near data".
7691 There is no runtime checking to prevent this from happening.
7694 The amount of stack being used is affected by the use of the "internal stack"
7695 to save registers before a subroutine call is made (---stack-auto will
7696 declare parameters and local variables on the stack) and the number of
7700 If you detect that the stack is over writing you data, then the following
7702 ---xstack will cause an external stack to be used for saving registers
7703 and (if ---stack-auto is being used) storing parameters and local variables.
7704 However this will produce more code which will be slower to execute.
7708 ---stack-loc will allow you specify the start of the stack, i.e.
7709 you could start it after any data in the general purpose area.
7710 However this may waste the memory not used by the register banks and if
7711 the size of the "near data" increases, it may creep into the bottom of
7715 ---stack-after-data, similar to the ---stack-loc, but it automatically places
7716 the stack after the end of the "near data".
7717 Again this could waste any spare register space.
7720 ---data-loc allows you to specify the start address of the near data.
7721 This could be used to move the "near data" further away from the stack
7722 giving it more room to grow.
7723 This will only work if no bit variables are being used and the stack can
7724 grow to use the bit variable space.
7732 If you find that the stack is over writing your bit variables or "near data"
7733 then the approach which best utilised the internal memory is to position
7734 the "near data" after the last bank of used registers or, if you use bit
7735 variables, after the last bit variable by using the ---data-loc, e.g.
7736 if two register banks are being used and no bit variables, ---data-loc
7737 16, and use the ---stack-after-data option.
7740 If bit variables are being used, another method would be to try and squeeze
7741 the data area in the unused register banks if it will fit, and start the
7742 stack after the last bit variable.
7745 Retargetting for other MCUs.
7748 The issues for retargetting the compiler are far too numerous to be covered
7750 What follows is a brief description of each of the seven phases of the
7751 compiler and its MCU dependency.
7754 Parsing the source and building the annotated parse tree.
7755 This phase is largely MCU independent (except for the language extensions).
7756 Syntax & semantic checks are also done in this phase, along with some initial
7757 optimizations like back patching labels and the pattern matching optimizations
7758 like bit-rotation etc.
7761 The second phase involves generating an intermediate code which can be easy
7762 manipulated during the later phases.
7763 This phase is entirely MCU independent.
7764 The intermediate code generation assumes the target machine has unlimited
7765 number of registers, and designates them with the name iTemp.
7766 The compiler can be made to dump a human readable form of the code generated
7767 by using the ---dumpraw option.
7770 This phase does the bulk of the standard optimizations and is also MCU independe
7772 This phase can be broken down into several sub-phases:
7776 Break down intermediate code (iCode) into basic blocks.
7778 Do control flow & data flow analysis on the basic blocks.
7780 Do local common subexpression elimination, then global subexpression elimination
7782 Dead code elimination
7786 If loop optimizations caused any changes then do 'global subexpression eliminati
7787 on' and 'dead code elimination' again.
7790 This phase determines the live-ranges; by live range I mean those iTemp
7791 variables defined by the compiler that still survive after all the optimization
7793 Live range analysis is essential for register allocation, since these computati
7794 on determines which of these iTemps will be assigned to registers, and for
7798 Phase five is register allocation.
7799 There are two parts to this process.
7803 The first part I call 'register packing' (for lack of a better term).
7804 In this case several MCU specific expression folding is done to reduce
7809 The second part is more MCU independent and deals with allocating registers
7810 to the remaining live ranges.
7811 A lot of MCU specific code does creep into this phase because of the limited
7812 number of index registers available in the 8051.
7815 The Code generation phase is (unhappily), entirely MCU dependent and very
7816 little (if any at all) of this code can be reused for other MCU.
7817 However the scheme for allocating a homogenized assembler operand for each
7818 iCode operand may be reused.
7821 As mentioned in the optimization section the peep-hole optimizer is rule
7822 based system, which can reprogrammed for other MCUs.
7825 SDCDB - Source Level Debugger
7828 SDCC is distributed with a source level debugger.
7829 The debugger uses a command line interface, the command repertoire of the
7830 debugger has been kept as close to gdb (the GNU debugger) as possible.
7831 The configuration and build process is part of the standard compiler installati
7832 on, which also builds and installs the debugger in the target directory
7833 specified during configuration.
7834 The debugger allows you debug BOTH at the C source and at the ASM source
7838 Compiling for Debugging
7843 debug option must be specified for all files for which debug information
7845 The complier generates a .cdb file for each of these files.
7846 The linker updates the .cdb file with the address information.
7847 This .cdb is used by the debugger.
7850 How the Debugger Works
7853 When the ---debug option is specified the compiler generates extra symbol
7854 information some of which are put into the the assembler source and some
7855 are put into the .cdb file, the linker updates the .cdb file with the address
7856 information for the symbols.
7857 The debugger reads the symbolic information generated by the compiler &
7858 the address information generated by the linker.
7859 It uses the SIMULATOR (Daniel's S51) to execute the program, the program
7860 execution is controlled by the debugger.
7861 When a command is issued for the debugger, it translates it into appropriate
7862 commands for the simulator.
7865 Starting the Debugger
7868 The debugger can be started using the following command line.
7869 (Assume the file you are debugging has the file name foo).
7883 The debugger will look for the following files.
7886 foo.c - the source file.
7889 foo.cdb - the debugger symbol information file.
7892 foo.ihx - the intel hex format object file.
7895 Command Line Options.
7898 ---directory=<source file directory> this option can used to specify the
7899 directory search list.
7900 The debugger will look into the directory list specified for source, cdb
7902 The items in the directory list must be separated by ':', e.g.
7903 if the source files can be in the directories /home/src1 and /home/src2,
7904 the ---directory option should be ---directory=/home/src1:/home/src2.
7905 Note there can be no spaces in the option.
7909 -cd <directory> - change to the <directory>.
7912 -fullname - used by GUI front ends.
7915 -cpu <cpu-type> - this argument is passed to the simulator please see the
7916 simulator docs for details.
7919 -X <Clock frequency > this options is passed to the simulator please see
7920 the simulator docs for details.
7923 -s <serial port file> passed to simulator see the simulator docs for details.
7926 -S <serial in,out> passed to simulator see the simulator docs for details.
7932 As mention earlier the command interface for the debugger has been deliberately
7933 kept as close the GNU debugger gdb, as possible.
7934 This will help the integration with existing graphical user interfaces
7935 (like ddd, xxgdb or xemacs) existing for the GNU debugger.
7936 \layout Subsubsection
7938 break [line | file:line | function | file:function]
7941 Set breakpoint at specified line or function:
7950 sdcdb>break foo.c:100
7954 sdcdb>break foo.c:funcfoo
7955 \layout Subsubsection
7957 clear [line | file:line | function | file:function ]
7960 Clear breakpoint at specified line or function:
7969 sdcdb>clear foo.c:100
7973 sdcdb>clear foo.c:funcfoo
7974 \layout Subsubsection
7979 Continue program being debugged, after breakpoint.
7980 \layout Subsubsection
7985 Execute till the end of the current function.
7986 \layout Subsubsection
7991 Delete breakpoint number 'n'.
7992 If used without any option clear ALL user defined break points.
7993 \layout Subsubsection
7995 info [break | stack | frame | registers ]
7998 info break - list all breakpoints
8001 info stack - show the function call stack.
8004 info frame - show information about the current execution frame.
8007 info registers - show content of all registers.
8008 \layout Subsubsection
8013 Step program until it reaches a different source line.
8014 \layout Subsubsection
8019 Step program, proceeding through subroutine calls.
8020 \layout Subsubsection
8025 Start debugged program.
8026 \layout Subsubsection
8031 Print type information of the variable.
8032 \layout Subsubsection
8037 print value of variable.
8038 \layout Subsubsection
8043 load the given file name.
8044 Note this is an alternate method of loading file for debugging.
8045 \layout Subsubsection
8050 print information about current frame.
8051 \layout Subsubsection
8056 Toggle between C source & assembly source.
8057 \layout Subsubsection
8062 Send the string following '!' to the simulator, the simulator response is
8064 Note the debugger does not interpret the command being sent to the simulator,
8065 so if a command like 'go' is sent the debugger can loose its execution
8066 context and may display incorrect values.
8067 \layout Subsubsection
8074 My name is Bobby Brown"
8077 Interfacing with XEmacs.
8080 Two files (in emacs lisp) are provided for the interfacing with XEmacs,
8081 sdcdb.el and sdcdbsrc.el.
8082 These two files can be found in the $(prefix)/bin directory after the installat
8084 These files need to be loaded into XEmacs for the interface to work.
8085 This can be done at XEmacs startup time by inserting the following into
8086 your '.xemacs' file (which can be found in your HOME directory):
8092 (load-file sdcdbsrc.el)
8098 .xemacs is a lisp file so the () around the command is REQUIRED.
8099 The files can also be loaded dynamically while XEmacs is running, set the
8100 environment variable 'EMACSLOADPATH' to the installation bin directory
8101 (<installdir>/bin), then enter the following command ESC-x load-file sdcdbsrc.
8102 To start the interface enter the following command:
8116 You will prompted to enter the file name to be debugged.
8121 The command line options that are passed to the simulator directly are bound
8122 to default values in the file sdcdbsrc.el.
8123 The variables are listed below, these values maybe changed as required.
8126 sdcdbsrc-cpu-type '51
8129 sdcdbsrc-frequency '11059200
8135 The following is a list of key mapping for the debugger interface.
8143 ;; Current Listing ::
8160 binding\SpecialChar ~
8199 ------\SpecialChar ~
8239 sdcdb-next-from-src\SpecialChar ~
8265 sdcdb-back-from-src\SpecialChar ~
8291 sdcdb-cont-from-src\SpecialChar ~
8301 SDCDB continue command
8317 sdcdb-step-from-src\SpecialChar ~
8343 sdcdb-whatis-c-sexp\SpecialChar ~
8353 SDCDB ptypecommand for data at
8417 sdcdbsrc-delete\SpecialChar ~
8431 SDCDB Delete all breakpoints if no arg
8479 given or delete arg (C-u arg x)
8495 sdcdbsrc-frame\SpecialChar ~
8510 SDCDB Display current frame if no arg,
8559 given or display frame arg
8624 sdcdbsrc-goto-sdcdb\SpecialChar ~
8634 Goto the SDCDB output buffer
8650 sdcdb-print-c-sexp\SpecialChar ~
8661 SDCDB print command for data at
8725 sdcdbsrc-goto-sdcdb\SpecialChar ~
8735 Goto the SDCDB output buffer
8751 sdcdbsrc-mode\SpecialChar ~
8767 Toggles Sdcdbsrc mode (turns it off)
8771 ;; C-c C-f\SpecialChar ~
8779 sdcdb-finish-from-src\SpecialChar ~
8787 SDCDB finish command
8791 ;; C-x SPC\SpecialChar ~
8799 sdcdb-break\SpecialChar ~
8817 Set break for line with point
8819 ;; ESC t\SpecialChar ~
8829 sdcdbsrc-mode\SpecialChar ~
8845 Toggle Sdcdbsrc mode
8847 ;; ESC m\SpecialChar ~
8857 sdcdbsrc-srcmode\SpecialChar ~
8881 The Z80 and gbz80 port
8884 SDCC can target both the Zilog Z80 and the Nintendo Gameboy's Z80-like gbz80.
8885 The port is incomplete - long support is incomplete (mul, div and mod are
8886 unimplimented), and both float and bitfield support is missing.
8887 Apart from that the code generated is correct.
8890 As always, the code is the authoritave reference - see z80/ralloc.c and z80/gen.c.
8891 The stack frame is similar to that generated by the IAR Z80 compiler.
8892 IX is used as the base pointer, HL is used as a temporary register, and
8893 BC and DE are available for holding varibles.
8894 IY is currently unusued.
8895 Return values are stored in HL.
8896 One bad side effect of using IX as the base pointer is that a functions
8897 stack frame is limited to 127 bytes - this will be fixed in a later version.
8903 SDCC has grown to be a large project.
8904 The compiler alone (without the preprocessor, assembler and linker) is
8905 about 40,000 lines of code (blank stripped).
8906 The open source nature of this project is a key to its continued growth
8908 You gain the benefit and support of many active software developers and
8910 Is SDCC perfect? No, that's why we need your help.
8911 The developers take pride in fixing reported bugs.
8912 You can help by reporting the bugs and helping other SDCC users.
8913 There are lots of ways to contribute, and we encourage you to take part
8914 in making SDCC a great software package.
8920 Send an email to the mailing list at 'user-sdcc@sdcc.sourceforge.net' or 'devel-sd
8921 cc@sdcc.sourceforge.net'.
8922 Bugs will be fixed ASAP.
8923 When reporting a bug, it is very useful to include a small test program
8924 which reproduces the problem.
8925 If you can isolate the problem by looking at the generated assembly code,
8926 this can be very helpful.
8927 Compiling your program with the ---dumpall option can sometimes be useful
8928 in locating optimization problems.
8934 The anatomy of the compiler
8939 This is an excerpt from an atricle published in Circuit Cellar MagaZine
8941 It's a little outdated (the compiler is much more efficient now and user/devell
8942 oper friendly), but pretty well exposes the guts of it all.
8948 The current version of SDCC can generate code for Intel 8051 and Z80 MCU.
8949 It is fairly easy to retarget for other 8-bit MCU.
8950 Here we take a look at some of the internals of the compiler.
8957 Parsing the input source file and creating an AST (Annotated Syntax Tree).
8958 This phase also involves propagating types (annotating each node of the
8959 parse tree with type information) and semantic analysis.
8960 There are some MCU specific parsing rules.
8961 For example the storage classes, the extended storage classes are MCU specific
8962 while there may be a xdata storage class for 8051 there is no such storage
8963 class for z80 or Atmel AVR.
8964 SDCC allows MCU specific storage class extensions, i.e.
8965 xdata will be treated as a storage class specifier when parsing 8051 C
8966 code but will be treated as a C identifier when parsing z80 or ATMEL AVR
8973 Intermediate code generation.
8974 In this phase the AST is broken down into three-operand form (iCode).
8975 These three operand forms are represented as doubly linked lists.
8976 ICode is the term given to the intermediate form generated by the compiler.
8977 ICode example section shows some examples of iCode generated for some simple
8984 Bulk of the target independent optimizations is performed in this phase.
8985 The optimizations include constant propagation, common sub-expression eliminati
8986 on, loop invariant code movement, strength reduction of loop induction variables
8987 and dead-code elimination.
8993 During intermediate code generation phase, the compiler assumes the target
8994 machine has infinite number of registers and generates a lot of temporary
8996 The live range computation determines the lifetime of each of these compiler-ge
8997 nerated temporaries.
8998 A picture speaks a thousand words.
8999 ICode example sections show the live range annotations for each of the
9001 It is important to note here, each iCode is assigned a number in the order
9002 of its execution in the function.
9003 The live ranges are computed in terms of these numbers.
9004 The from number is the number of the iCode which first defines the operand
9005 and the to number signifies the iCode which uses this operand last.
9011 The register allocation determines the type and number of registers needed
9013 In most MCUs only a few registers can be used for indirect addressing.
9014 In case of 8051 for example the registers R0 & R1 can be used to indirectly
9015 address the internal ram and DPTR to indirectly address the external ram.
9016 The compiler will try to allocate the appropriate register to pointer variables
9018 ICode example section shows the operands annotated with the registers assigned
9020 The compiler will try to keep operands in registers as much as possible;
9021 there are several schemes the compiler uses to do achieve this.
9022 When the compiler runs out of registers the compiler will check to see
9023 if there are any live operands which is not used or defined in the current
9024 basic block being processed, if there are any found then it will push that
9025 operand and use the registers in this block, the operand will then be popped
9026 at the end of the basic block.
9030 There are other MCU specific considerations in this phase.
9031 Some MCUs have an accumulator; very short-lived operands could be assigned
9032 to the accumulator instead of general-purpose register.
9038 Figure II gives a table of iCode operations supported by the compiler.
9039 The code generation involves translating these operations into corresponding
9040 assembly code for the processor.
9041 This sounds overly simple but that is the essence of code generation.
9042 Some of the iCode operations are generated on a MCU specific manner for
9043 example, the z80 port does not use registers to pass parameters so the
9044 SEND and RECV iCode operations will not be generated, and it also does
9045 not support JUMPTABLES.
9052 <Where is Figure II ?>
9058 This section shows some details of iCode.
9059 The example C code does not do anything useful; it is used as an example
9060 to illustrate the intermediate code generated by the compiler.
9073 /* This function does nothing useful.
9080 for the purpose of explaining iCode */
9083 short function (data int *x)
9091 short i=10; /* dead initialization eliminated */
9096 short sum=10; /* dead initialization eliminated */
9109 while (*x) *x++ = *p++;
9123 /* compiler detects i,j to be induction variables */
9127 for (i = 0, j = 10 ; i < 10 ; i++, j---) {
9139 mul += i * 3; /* this multiplication remains */
9145 gint += j * 3;/* this multiplication changed to addition */
9162 In addition to the operands each iCode contains information about the filename
9163 and line it corresponds to in the source file.
9164 The first field in the listing should be interpreted as follows:
9169 Filename(linenumber: iCode Execution sequence number : ICode hash table
9170 key : loop depth of the iCode).
9175 Then follows the human readable form of the ICode operation.
9176 Each operand of this triplet form can be of three basic types a) compiler
9177 generated temporary b) user defined variable c) a constant value.
9178 Note that local variables and parameters are replaced by compiler generated
9180 Live ranges are computed only for temporaries (i.e.
9181 live ranges are not computed for global variables).
9182 Registers are allocated for temporaries only.
9183 Operands are formatted in the following manner:
9188 Operand Name [lr live-from : live-to ] { type information } [ registers
9194 As mentioned earlier the live ranges are computed in terms of the execution
9195 sequence number of the iCodes, for example
9197 the iTemp0 is live from (i.e.
9198 first defined in iCode with execution sequence number 3, and is last used
9199 in the iCode with sequence number 5).
9200 For induction variables such as iTemp21 the live range computation extends
9201 the lifetime from the start to the end of the loop.
9203 The register allocator used the live range information to allocate registers,
9204 the same registers may be used for different temporaries if their live
9205 ranges do not overlap, for example r0 is allocated to both iTemp6 and to
9206 iTemp17 since their live ranges do not overlap.
9207 In addition the allocator also takes into consideration the type and usage
9208 of a temporary, for example itemp6 is a pointer to near space and is used
9209 as to fetch data from (i.e.
9210 used in GET_VALUE_AT_ADDRESS) so it is allocated a pointer registers (r0).
9211 Some short lived temporaries are allocated to special registers which have
9212 meaning to the code generator e.g.
9213 iTemp13 is allocated to a pseudo register CC which tells the back end that
9214 the temporary is used only for a conditional jump the code generation makes
9215 use of this information to optimize a compare and jump ICode.
9217 There are several loop optimizations performed by the compiler.
9218 It can detect induction variables iTemp21(i) and iTemp23(j).
9219 Also note the compiler does selective strength reduction, i.e.
9220 the multiplication of an induction variable in line 18 (gint = j * 3) is
9221 changed to addition, a new temporary iTemp17 is allocated and assigned
9222 a initial value, a constant 3 is then added for each iteration of the loop.
9223 The compiler does not change the multiplication in line 17 however since
9224 the processor does support an 8 * 8 bit multiplication.
9226 Note the dead code elimination optimization eliminated the dead assignments
9227 in line 7 & 8 to I and sum respectively.
9234 Sample.c (5:1:0:0) _entry($9) :
9239 Sample.c(5:2:1:0) proc _function [lr0:0]{function short}
9244 Sample.c(11:3:2:0) iTemp0 [lr3:5]{_near * int}[r2] = recv
9249 Sample.c(11:4:53:0) preHeaderLbl0($11) :
9254 Sample.c(11:5:55:0) iTemp6 [lr5:16]{_near * int}[r0] := iTemp0 [lr3:5]{_near
9260 Sample.c(11:6:5:1) _whilecontinue_0($1) :
9265 Sample.c(11:7:7:1) iTemp4 [lr7:8]{int}[r2 r3] = @[iTemp6 [lr5:16]{_near *
9271 Sample.c(11:8:8:1) if iTemp4 [lr7:8]{int}[r2 r3] == 0 goto _whilebreak_0($3)
9276 Sample.c(11:9:14:1) iTemp7 [lr9:13]{_far * int}[DPTR] := _p [lr0:0]{_far
9282 Sample.c(11:10:15:1) _p [lr0:0]{_far * int} = _p [lr0:0]{_far * int} + 0x2
9288 Sample.c(11:13:18:1) iTemp10 [lr13:14]{int}[r2 r3] = @[iTemp7 [lr9:13]{_far
9294 Sample.c(11:14:19:1) *(iTemp6 [lr5:16]{_near * int}[r0]) := iTemp10 [lr13:14]{int
9300 Sample.c(11:15:12:1) iTemp6 [lr5:16]{_near * int}[r0] = iTemp6 [lr5:16]{_near
9301 * int}[r0] + 0x2 {short}
9306 Sample.c(11:16:20:1) goto _whilecontinue_0($1)
9311 Sample.c(11:17:21:0)_whilebreak_0($3) :
9316 Sample.c(12:18:22:0) iTemp2 [lr18:40]{short}[r2] := 0x0 {short}
9321 Sample.c(13:19:23:0) iTemp11 [lr19:40]{short}[r3] := 0x0 {short}
9326 Sample.c(15:20:54:0)preHeaderLbl1($13) :
9331 Sample.c(15:21:56:0) iTemp21 [lr21:38]{short}[r4] := 0x0 {short}
9336 Sample.c(15:22:57:0) iTemp23 [lr22:38]{int}[r5 r6] := 0xa {int}
9341 Sample.c(15:23:58:0) iTemp17 [lr23:38]{int}[r7 r0] := 0x1e {int}
9346 Sample.c(15:24:26:1)_forcond_0($4) :
9351 Sample.c(15:25:27:1) iTemp13 [lr25:26]{char}[CC] = iTemp21 [lr21:38]{short}[r4]
9357 Sample.c(15:26:28:1) if iTemp13 [lr25:26]{char}[CC] == 0 goto _forbreak_0($7)
9362 Sample.c(16:27:31:1) iTemp2 [lr18:40]{short}[r2] = iTemp2 [lr18:40]{short}[r2]
9363 + ITemp21 [lr21:38]{short}[r4]
9368 Sample.c(17:29:33:1) iTemp15 [lr29:30]{short}[r1] = iTemp21 [lr21:38]{short}[r4]
9374 Sample.c(17:30:34:1) iTemp11 [lr19:40]{short}[r3] = iTemp11 [lr19:40]{short}[r3]
9375 + iTemp15 [lr29:30]{short}[r1]
9380 Sample.c(18:32:36:1:1) iTemp17 [lr23:38]{int}[r7 r0]= iTemp17 [lr23:38]{int}[r7
9386 Sample.c(18:33:37:1) _gint [lr0:0]{int} = _gint [lr0:0]{int} + iTemp17 [lr23:38]{
9392 Sample.c(15:36:42:1) iTemp21 [lr21:38]{short}[r4] = iTemp21 [lr21:38]{short}[r4]
9398 Sample.c(15:37:45:1) iTemp23 [lr22:38]{int}[r5 r6]= iTemp23 [lr22:38]{int}[r5
9404 Sample.c(19:38:47:1) goto _forcond_0($4)
9409 Sample.c(19:39:48:0)_forbreak_0($7) :
9414 Sample.c(20:40:49:0) iTemp24 [lr40:41]{short}[DPTR] = iTemp2 [lr18:40]{short}[r2]
9415 + ITemp11 [lr19:40]{short}[r3]
9420 Sample.c(20:41:50:0) ret iTemp24 [lr40:41]{short}
9425 Sample.c(20:42:51:0)_return($8) :
9430 Sample.c(20:43:52:0) eproc _function [lr0:0]{ ia0 re0 rm0}{function short}
9436 Finally the code generated for this function:
9477 ; ----------------------------------------------
9487 ; ----------------------------------------------
9497 ; iTemp0 [lr3:5]{_near * int}[r2] = recv
9509 ; iTemp6 [lr5:16]{_near * int}[r0] := iTemp0 [lr3:5]{_near * int}[r2]
9521 ;_whilecontinue_0($1) :
9531 ; iTemp4 [lr7:8]{int}[r2 r3] = @[iTemp6 [lr5:16]{_near * int}[r0]]
9536 ; if iTemp4 [lr7:8]{int}[r2 r3] == 0 goto _whilebreak_0($3)
9595 ; iTemp7 [lr9:13]{_far * int}[DPTR] := _p [lr0:0]{_far * int}
9614 ; _p [lr0:0]{_far * int} = _p [lr0:0]{_far * int} + 0x2 {short}
9661 ; iTemp10 [lr13:14]{int}[r2 r3] = @[iTemp7 [lr9:13]{_far * int}[DPTR]]
9701 ; *(iTemp6 [lr5:16]{_near * int}[r0]) := iTemp10 [lr13:14]{int}[r2 r3]
9727 ; iTemp6 [lr5:16]{_near * int}[r0] =
9732 ; iTemp6 [lr5:16]{_near * int}[r0] +
9749 ; goto _whilecontinue_0($1)
9761 ; _whilebreak_0($3) :
9771 ; iTemp2 [lr18:40]{short}[r2] := 0x0 {short}
9783 ; iTemp11 [lr19:40]{short}[r3] := 0x0 {short}
9795 ; iTemp21 [lr21:38]{short}[r4] := 0x0 {short}
9807 ; iTemp23 [lr22:38]{int}[r5 r6] := 0xa {int}
9826 ; iTemp17 [lr23:38]{int}[r7 r0] := 0x1e {int}
9855 ; iTemp13 [lr25:26]{char}[CC] = iTemp21 [lr21:38]{short}[r4] < 0xa {short}
9860 ; if iTemp13 [lr25:26]{char}[CC] == 0 goto _forbreak_0($7)
9905 ; iTemp2 [lr18:40]{short}[r2] = iTemp2 [lr18:40]{short}[r2] +
9910 ; iTemp21 [lr21:38]{short}[r4]
9936 ; iTemp15 [lr29:30]{short}[r1] = iTemp21 [lr21:38]{short}[r4] * 0x3 {short}
9969 ; iTemp11 [lr19:40]{short}[r3] = iTemp11 [lr19:40]{short}[r3] +
9974 ; iTemp15 [lr29:30]{short}[r1]
9993 ; iTemp17 [lr23:38]{int}[r7 r0]= iTemp17 [lr23:38]{int}[r7 r0]- 0x3 {short}
10040 ; _gint [lr0:0]{int} = _gint [lr0:0]{int} + iTemp17 [lr23:38]{int}[r7 r0]
10087 ; iTemp21 [lr21:38]{short}[r4] = iTemp21 [lr21:38]{short}[r4] + 0x1 {short}
10099 ; iTemp23 [lr22:38]{int}[r5 r6]= iTemp23 [lr22:38]{int}[r5 r6]- 0x1 {short}
10113 cjne r5,#0xff,00104$
10125 ; goto _forcond_0($4)
10137 ; _forbreak_0($7) :
10147 ; ret iTemp24 [lr40:41]{short}
10190 A few words about basic block successors, predecessors and dominators
10193 Successors are basic blocks that might execute after this basic block.
10195 Predecessors are basic blocks that might execute before reaching this basic
10198 Dominators are basic blocks that WILL execute before reaching this basic
10224 a) succList of [BB2] = [BB4], of [BB3] = [BB4], of [BB1] = [BB2,BB3]
10227 b) predList of [BB2] = [BB1], of [BB3] = [BB1], of [BB4] = [BB2,BB3]
10230 c) domVect of [BB4] = BB1 ...
10231 here we are not sure if BB2 or BB3 was executed but we are SURE that BB1
10239 \begin_inset LatexCommand \url{http://sdcc.sourceforge.net#Who}
10249 Thanks to all the other volunteer developers who have helped with coding,
10250 testing, web-page creation, distribution sets, etc.
10251 You know who you are :-)
10258 This document was initially written by Sandeep Dutta
10261 All product names mentioned herein may be trademarks of their respective
10267 \begin_inset LatexCommand \printindex{}