1 #LyX 1.3 created this file. For more info see http://www.lyx.org/
6 pdftitle={SDCC Compiler User Guide},
7 pdfauthor={SDCC development team},
8 pdfsubject={installation, user manual},
9 pdfkeywords={8032, 8051, ansi, c, compiler, CPU, DS390,
10 embedded, GPL, manual, mcs51, PIC, small, Z80},
12 linkcolor=blue] {hyperref}
16 \inputencoding default
19 \paperfontsize default
26 \use_numerical_citations 0
27 \paperorientation portrait
34 \paragraph_separation indent
36 \quotes_language swedish
44 Please note: double dashed longoptions (e.g.
45 --version) are written this way: -
59 three consecutive dashes simply result in a long resp.
63 SDCC Compiler User Guide
69 The strings enclosed in $ are automatically updated by cvs:
74 cvs: $Revision$ $Date$
78 \begin_inset LatexCommand \tableofcontents{}
95 is a Freeware, retargettable, optimizing ANSI-C compiler by
99 designed for 8 bit Microprocessors.
100 The current version targets Intel MCS51 based Microprocessors (8031, 8032,
102 \begin_inset LatexCommand \index{8031, 8032, 8051, 8052 CPU}
106 , etc), Zilog Z80 based MCUs, and the Dallas DS80C390 variant.
107 It can be retargetted for other microprocessors, support for PIC, AVR and
108 186 is under development.
109 The entire source code for the compiler is distributed under GPL.
110 SDCC uses ASXXXX & ASLINK, a Freeware, retargettable assembler & linker.
111 SDCC has extensive language extensions suitable for utilizing various microcont
112 rollers and underlying hardware effectively.
117 In addition to the MCU specific optimizations SDCC also does a host of standard
121 global sub expression elimination,
124 loop optimizations (loop invariant, strength reduction of induction variables
128 constant folding & propagation,
134 dead code elimination
144 For the back-end SDCC uses a global register allocation scheme which should
145 be well suited for other 8 bit MCUs.
150 The peep hole optimizer uses a rule based substitution mechanism which is
156 Supported data-types are:
159 char (8 bits, 1 byte),
162 short and int (16 bits, 2 bytes),
165 long (32 bit, 4 bytes)
172 The compiler also allows
174 inline assembler code
176 to be embedded anywhere in a function.
177 In addition, routines developed in assembly can also be called.
181 SDCC also provides an option (-
191 -cyclomatic) to report the relative complexity of a function.
192 These functions can then be further optimized, or hand coded in assembly
198 SDCC also comes with a companion source level debugger SDCDB, the debugger
199 currently uses ucSim a freeware simulator for 8051 and other micro-controllers.
204 The latest version can be downloaded from
205 \begin_inset LatexCommand \url{http://sdcc.sourceforge.net/}
215 Please note: the compiler will probably always be some steps ahead of this
220 \begin_inset LatexCommand \index{Status of documentation}
230 Obviously this has pros and cons
239 All packages used in this compiler system are
247 ; source code for all the sub-packages (pre-processor, assemblers, linkers
248 etc) is distributed with the package.
249 This documentation is maintained using a freeware word processor (LyX).
251 This program is free software; you can redistribute it and/or modify it
252 under the terms of the GNU General Public License
253 \begin_inset LatexCommand \index{GNU General Public License, GPL}
257 as published by the Free Software Foundation; either version 2, or (at
258 your option) any later version.
259 This program is distributed in the hope that it will be useful, but WITHOUT
260 ANY WARRANTY; without even the implied warranty
261 \begin_inset LatexCommand \index{warranty}
265 of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
266 See the GNU General Public License for more details.
267 You should have received a copy of the GNU General Public License along
268 with this program; if not, write to the Free Software Foundation, 59 Temple
269 Place - Suite 330, Boston, MA 02111-1307, USA.
270 In other words, you are welcome to use, share and improve this program.
271 You are forbidden to forbid anyone else to use, share and improve what
273 Help stamp out software-hoarding!
276 Typographic conventions
277 \begin_inset LatexCommand \index{Typographic conventions}
284 Throughout this manual, we will use the following convention.
285 Commands you have to type in are printed in
293 Code samples are printed in
298 Interesting items and new terms are printed in
303 Compatibility with previous versions
306 This version has numerous bug fixes compared with the previous version.
307 But we also introduced some incompatibilities with older versions.
308 Not just for the fun of it, but to make the compiler more stable, efficient
310 \begin_inset LatexCommand \index{ANSI-compliance}
320 short is now equivalent to int (16 bits), it used to be equivalent to char
321 (8 bits) which is not ANSI compliant
324 the default directory for gcc-builds where include, library and documention
325 files are stored is now in /usr/local/share
328 char type parameters to vararg functions are casted to int unless explicitly
345 will push a as an int and as a char resp.
358 -regextend has been removed
371 -noregparms has been removed
384 -stack-after-data has been removed
389 <pending: more incompatibilities?>
395 What do you need before you start installation of SDCC? A computer, and
397 The preferred method of installation is to compile SDCC from source using
399 For Windows some pre-compiled binary distributions are available for your
401 You should have some experience with command line tools and compiler use.
407 The SDCC home page at
408 \begin_inset LatexCommand \url{http://sdcc.sourceforge.net/}
412 is a great place to find distribution sets.
413 You can also find links to the user mailing lists that offer help or discuss
414 SDCC with other SDCC users.
415 Web links to other SDCC related sites can also be found here.
416 This document can be found in the DOC directory of the source package as
418 Some of the other tools (simulator and assembler) included with SDCC contain
419 their own documentation and can be found in the source distribution.
420 If you want the latest unreleased software, the complete source package
421 is available directly by anonymous CVS on cvs.sdcc.sourceforge.net.
424 ANSI C reference / related tools / recommended reading / compiler building:
428 Wishes for the future
431 There are (and always will be) some things that could be done.
432 Here are some I can think of:
439 char KernelFunction3(char p) at 0x340;
447 \begin_inset LatexCommand \index{code banking (not supported)}
455 If you can think of some more, please see the chapter 9 about filing feature
457 \begin_inset LatexCommand \index{Requesting features}
462 \begin_inset LatexCommand \index{Feature request}
472 \begin_inset LatexCommand \index{Installation}
480 \begin_inset LatexCommand \index{Options SDCC configuration}
487 The install paths, search paths and other options are defined when running
489 The defaults can be overriden by:
491 \labelwidthstring 00.00.0000
503 -prefix see tabel below
505 \labelwidthstring 00.00.0000
517 -exec_prefix see tabel below
519 \labelwidthstring 00.00.0000
531 -bindir see tabel below
533 \labelwidthstring 00.00.0000
545 -datadir see tabel below
547 \labelwidthstring 00.00.0000
549 docdir environment variable, see tabel below
551 \labelwidthstring 00.00.0000
553 include_dir_suffix environment variable, see tabel below
555 \labelwidthstring 00.00.0000
557 lib_dir_suffix environment variable, see tabel below
559 \labelwidthstring 00.00.0000
561 sdccconf_h_dir_separator environment variable, either / or
566 This character will only be used in sdccconf.h; don't forget it's a C-header,
567 therefore a double-backslash is needed there.
569 \labelwidthstring 00.00.0000
581 -disable-mcs51-port Excludes the Intel mcs51 port
583 \labelwidthstring 00.00.0000
595 -disable-gbz80-port Excludes the Gameboy gbz80 port
597 \labelwidthstring 00.00.0000
609 -z80-port Excludes the z80 port
611 \labelwidthstring 00.00.0000
623 -disable-avr-port Excludes the AVR port
625 \labelwidthstring 00.00.0000
637 -disable-ds390-port Excludes the DS390 port
639 \labelwidthstring 00.00.0000
651 -disable-pic-port Excludes the PIC port
653 \labelwidthstring 00.00.0000
665 -disable-xa51-port Excludes the XA51 port
667 \labelwidthstring 00.00.0000
679 -disable-ucsim Disables configuring and building of ucsim
681 \labelwidthstring 00.00.0000
693 -disable-device-lib-build Disables automatically building device libraries
695 \labelwidthstring 00.00.0000
707 -disable-packihx Disables building packihx
709 \labelwidthstring 00.00.0000
721 -enable-libgc Use the Bohem memory allocator.
722 Lower runtime footprint.
725 Furthermore the environment variables CC, CFLAGS, ...
726 the tools and their arguments can be influenced.
727 Please see `configure -
737 -help` and the man/info pages of `configure` for details.
741 The names of the standard libraries STD_LIB, STD_INT_LIB, STD_LONG_LIB,
742 STD_FP_LIB, STD_DS390_LIB, STD_XA51_LIB and the environment variables SDCC_DIR_
743 NAME, SDCC_INCLUDE_NAME, SDCC_LIB_NAME are defined by `configure` too.
744 At the moment it's not possible to change the default settings (it was
745 simply never required.
749 These configure options are compiled into the binaries, and can only be
750 changed by rerunning 'configure' and recompiling SDCC.
751 The configure options are written in
755 to distinguish them from run time environment variables (see section search
761 \begin_inset Quotes sld
765 \begin_inset Quotes srd
768 are used by the SDCC team to build the official Win32 binaries.
769 The SDCC team uses Mingw32 to build the official Windows binaries, because
776 a gcc compiler and last but not least
779 the binaries can be built by cross compiling on Sourceforge's compile farm.
782 See the examples, how to pass the Win32 settings to 'configure'.
783 The other Win32 builds using Borland, VC or whatever don't use 'configure',
784 but a header file sdcc_vc_in.h is the same as sdccconf.h built by 'configure'
795 <lyxtabular version="3" rows="8" columns="3">
797 <column alignment="block" valignment="top" leftline="true" width="0in">
798 <column alignment="block" valignment="top" leftline="true" width="0in">
799 <column alignment="block" valignment="top" leftline="true" rightline="true" width="0in">
800 <row topline="true" bottomline="true">
801 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
809 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
817 <cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
827 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
837 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
845 <cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
857 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
867 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
877 <cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
889 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
899 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
911 <cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
927 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
937 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
949 <cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
961 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
971 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
983 <cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
999 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
1009 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
1017 <cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
1026 <row topline="true" bottomline="true">
1027 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
1037 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
1045 <cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
1064 'configure' also computes relative paths.
1065 This is needed for full relocatability of a binary package and to complete
1066 search paths (see section search paths below):
1071 \begin_inset Tabular
1072 <lyxtabular version="3" rows="4" columns="3">
1074 <column alignment="block" valignment="top" leftline="true" width="0in">
1075 <column alignment="block" valignment="top" leftline="true" width="0in">
1076 <column alignment="block" valignment="top" leftline="true" rightline="true" width="0in">
1077 <row topline="true" bottomline="true">
1078 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
1086 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
1094 <cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
1103 <row topline="true" bottomline="true">
1104 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
1114 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
1122 <cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
1133 <row bottomline="true">
1134 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
1144 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
1152 <cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
1161 <row bottomline="true">
1162 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
1172 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
1180 <cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
1202 ./configure --prefix=
1203 \begin_inset Quotes srd
1207 \begin_inset Quotes srd
1211 \begin_inset Quotes srd
1215 \begin_inset Quotes srd
1221 ./configure --disable-avr-port --disable-xa51-port
1224 To crosscompile on linux for Mingw32 (see also 'sdcc/support/scripts/sdcc_mingw3
1234 \begin_inset Quotes srd
1237 i586-mingw32msvc-gcc
1238 \begin_inset Quotes srd
1242 \begin_inset Quotes srd
1245 i586-mingw32msvc-g++
1246 \begin_inset Quotes srd
1255 \begin_inset Quotes srd
1258 i586-mingw32msvc-ranlib
1259 \begin_inset Quotes srd
1268 \begin_inset Quotes srd
1271 i586-mingw32msvc-strip
1272 \begin_inset Quotes srd
1281 \begin_inset Quotes srd
1285 \begin_inset Quotes srd
1294 \begin_inset Quotes srd
1298 \begin_inset Quotes srd
1307 \begin_inset Quotes srd
1311 \begin_inset Quotes srd
1320 \begin_inset Quotes srd
1324 \begin_inset Quotes srd
1333 \begin_inset Quotes srd
1337 \begin_inset Quotes srd
1345 sdccconf_h_dir_separator=
1346 \begin_inset Quotes srd
1358 \begin_inset Quotes srd
1366 --disable-device-lib-build
1376 --host=i586-mingw32msvc --build=unknown-unknown-linux-gnu
1380 \begin_inset Quotes sld
1384 \begin_inset Quotes srd
1387 compile on Cygwin for Mingw32(see also sdcc/support/scripts/sdcc_cygwin_mingw32)
1397 \begin_inset Quotes srd
1401 \begin_inset Quotes srd
1410 \begin_inset Quotes srd
1414 \begin_inset Quotes srd
1423 \begin_inset Quotes srd
1427 \begin_inset Quotes srd
1436 \begin_inset Quotes srd
1440 \begin_inset Quotes srd
1449 \begin_inset Quotes srd
1453 \begin_inset Quotes srd
1462 \begin_inset Quotes srd
1466 \begin_inset Quotes srd
1475 \begin_inset Quotes srd
1479 \begin_inset Quotes srd
1487 sdccconf_h_dir_separator=
1488 \begin_inset Quotes srd
1500 \begin_inset Quotes srd
1511 'configure' is quite slow on Cygwin (at least on windows before Win2000/XP).
1522 -C' turns on caching, which gives a little bit extra speed.
1523 However if options are changed, it can be necessary to delete the config.cache
1528 \begin_inset LatexCommand \index{Install paths}
1536 Binary files (preprocessor, assembler and linker)
1540 \begin_inset Tabular
1541 <lyxtabular version="3" rows="2" columns="3">
1543 <column alignment="block" valignment="top" leftline="true" width="0in">
1544 <column alignment="block" valignment="top" leftline="true" width="0in">
1545 <column alignment="block" valignment="top" leftline="true" rightline="true" width="0in">
1546 <row topline="true" bottomline="true">
1547 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
1555 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
1563 <cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
1572 <row topline="true" bottomline="true">
1573 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
1583 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
1591 <cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
1617 \begin_inset Tabular
1618 <lyxtabular version="3" rows="2" columns="3">
1620 <column alignment="block" valignment="top" leftline="true" width="1.6in">
1621 <column alignment="block" valignment="top" leftline="true" width="0in">
1622 <column alignment="block" valignment="top" leftline="true" rightline="true" width="0in">
1623 <row topline="true" bottomline="true">
1624 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
1632 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
1640 <cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
1649 <row topline="true" bottomline="true">
1650 <cell alignment="left" valignment="top" topline="true" leftline="true" usebox="none">
1662 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
1667 /usr/local/share/sdcc/include
1670 <cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
1696 is auto-appended by the compiler, e.g.
1697 small, large, z80, ds390 etc.)
1701 \begin_inset Tabular
1702 <lyxtabular version="3" rows="2" columns="3">
1704 <column alignment="block" valignment="top" leftline="true" width="0in">
1705 <column alignment="block" valignment="top" leftline="true" width="0in">
1706 <column alignment="block" valignment="top" leftline="true" rightline="true" width="0in">
1707 <row topline="true" bottomline="true">
1708 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
1716 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
1724 <cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
1733 <row topline="true" bottomline="true">
1734 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
1741 $DATADIR/$LIB_DIR_SUFFIX
1744 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
1749 /usr/local/share/sdcc/lib
1752 <cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
1778 \begin_inset Tabular
1779 <lyxtabular version="3" rows="2" columns="3">
1781 <column alignment="block" valignment="top" leftline="true" width="0in">
1782 <column alignment="block" valignment="top" leftline="true" width="0in">
1783 <column alignment="block" valignment="top" leftline="true" rightline="true" width="0in">
1784 <row topline="true" bottomline="true">
1785 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
1793 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
1801 <cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
1810 <row topline="true" bottomline="true">
1811 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
1821 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
1826 /usr/local/share/sdcc/doc
1829 <cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
1850 The install paths can still be changed during `make install` with e.g.:
1853 make install prefix=$(HOME)/local/sdcc
1856 Of course this doesn't change the search paths compiled into the binaries.
1860 \begin_inset LatexCommand \index{Search path}
1867 Some search paths or parts of them are determined by configure variables
1872 , see section above).
1873 Further search paths are determined by environment variables during runtime.
1876 The paths searched when running the compiler are as follows (the first catch
1882 Binary files (preprocessor, assembler and linker)
1885 \begin_inset Tabular
1886 <lyxtabular version="3" rows="4" columns="3">
1888 <column alignment="block" valignment="top" leftline="true" width="0in">
1889 <column alignment="block" valignment="top" leftline="true" width="0in">
1890 <column alignment="block" valignment="top" leftline="true" rightline="true" width="0in">
1891 <row topline="true" bottomline="true">
1892 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
1900 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
1908 <cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
1917 <row topline="true">
1918 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
1928 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
1936 <cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
1947 <row topline="true">
1948 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
1953 Path of argv[0] (if available)
1956 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
1964 <cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
1973 <row topline="true" bottomline="true">
1974 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
1982 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
1990 <cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
2011 \begin_inset Tabular
2012 <lyxtabular version="3" rows="6" columns="3">
2014 <column alignment="block" valignment="top" leftline="true" width="1.5in">
2015 <column alignment="block" valignment="top" leftline="true" width="1.5in">
2016 <column alignment="block" valignment="top" leftline="true" rightline="true" width="0in">
2017 <row topline="true" bottomline="true">
2018 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
2026 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
2034 <cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
2043 <row topline="true">
2044 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
2062 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
2080 <cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
2099 <row topline="true">
2100 <cell alignment="left" valignment="top" topline="true" leftline="true" usebox="none">
2108 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
2116 <cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
2125 <row topline="true">
2126 <cell alignment="left" valignment="top" topline="true" leftline="true" usebox="none">
2140 <cell alignment="left" valignment="top" topline="true" leftline="true" usebox="none">
2152 <cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
2163 <row topline="true">
2164 <cell alignment="left" valignment="top" topline="true" leftline="true" usebox="none">
2182 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
2232 <cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
2245 <row topline="true" bottomline="true">
2246 <cell alignment="left" valignment="top" topline="true" leftline="true" usebox="none">
2262 <cell alignment="left" valignment="top" topline="true" leftline="true" usebox="none">
2267 /usr/local/share/sdcc/
2272 <cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
2299 -nostdinc disables the last two search paths.
2306 With the exception of
2307 \begin_inset Quotes sld
2321 \begin_inset Quotes srd
2328 is auto-appended by the compiler (e.g.
2329 small, large, z80, ds390 etc.).
2333 \begin_inset Tabular
2334 <lyxtabular version="3" rows="6" columns="3">
2336 <column alignment="block" valignment="top" leftline="true" width="1.7in">
2337 <column alignment="block" valignment="top" leftline="true" width="1.2in">
2338 <column alignment="block" valignment="top" leftline="true" rightline="true" width="1.2in">
2339 <row topline="true" bottomline="true">
2340 <cell alignment="left" valignment="top" topline="true" leftline="true" usebox="none">
2348 <cell alignment="left" valignment="top" topline="true" leftline="true" usebox="none">
2356 <cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
2365 <row topline="true">
2366 <cell alignment="left" valignment="top" topline="true" leftline="true" usebox="none">
2384 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
2402 <cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
2421 <row topline="true">
2422 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
2434 <cell alignment="left" valignment="top" topline="true" leftline="true" usebox="none">
2446 <cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
2461 <row topline="true">
2462 <cell alignment="left" valignment="top" topline="true" leftline="true" usebox="none">
2473 $LIB_DIR_SUFFIX/<model>
2476 <cell alignment="left" valignment="top" topline="true" leftline="true" usebox="none">
2490 <cell alignment="left" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
2507 <row topline="true">
2508 <cell alignment="left" valignment="top" topline="true" leftline="true" usebox="none">
2523 $LIB_DIR_SUFFIX/<model>
2526 <cell alignment="left" valignment="top" topline="true" leftline="true" usebox="none">
2579 <cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
2635 <row topline="true" bottomline="true">
2636 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
2645 $LIB_DIR_SUFFIX/<model>
2648 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
2653 /usr/local/share/sdcc/
2660 <cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
2676 Don't delete any of the stray spaces in the table above without checking
2677 the HTML output (last line)!
2693 -nostdlib disables the last two search paths.
2697 \begin_inset LatexCommand \index{Building SDCC}
2702 \layout Subsubsection
2704 Building SDCC on Linux
2709 Download the source package
2711 either from the SDCC CVS repository or from the
2712 \begin_inset LatexCommand \url[nightly snapshots]{http://sdcc.sourceforge.net/snap.php}
2718 , it will be named something like sdcc
2731 Bring up a command line terminal, such as xterm.
2736 Unpack the file using a command like:
2739 "tar -xzf sdcc.src.tar.gz
2744 , this will create a sub-directory called sdcc with all of the sources.
2747 Change directory into the main SDCC directory, for example type:
2764 This configures the package for compilation on your system.
2780 All of the source packages will compile, this can take a while.
2796 This copies the binary executables, the include files, the libraries and
2797 the documentation to the install directories.
2798 \layout Subsubsection
2800 Building SDCC on OSX 2.x
2803 Follow the instruction for Linux.
2807 On OSX 2.x it was reported, that the default gcc (version 3.1 20020420 (prerelease
2808 )) fails to compile SDCC.
2809 Fortunately there's also gcc 2.9.x installed, which works fine.
2810 This compiler can be selected by running 'configure' with:
2813 ./configure CC=gcc2 CXX=g++2
2814 \layout Subsubsection
2816 Crosscompiling SDCC on Linux for Windows
2819 With the Mingw32 gcc crosscompiler it's easy to compile SDCC for Win32.
2820 See section 'Configure Options'.
2821 \layout Subsubsection
2823 Building SDCC on Windows
2826 With the exception of Cygwin the SDCC binaries uCsim and sdcdb can't be
2828 They use Unix-sockets, which are not available on Win32.
2829 \layout Subsubsection
2831 Windows Install Using a Binary Package
2834 Download the binary package and unpack it using your favorite unpacking
2835 tool (gunzip, WinZip, etc).
2836 This should unpack to a group of sub-directories.
2837 An example directory structure after unpacking the mingw32 package is:
2842 bin for the executables, c:
2850 lib for the include and libraries.
2853 Adjust your environment variable PATH to include the location of the bin
2854 directory or start sdcc using the full path.
2855 \layout Subsubsection
2857 Building SDCC using Cygwin and Mingw32
2860 For building and installing a Cygwin executable follow the instructions
2866 \begin_inset Quotes sld
2870 \begin_inset Quotes srd
2873 Win32-binary can be built, which will not need the Cygwin-DLL.
2874 For the necessary 'configure' options see section 'configure options' or
2875 the script 'sdcc/support/scripts/sdcc_cygwinmingw32'.
2879 In order to install Cygwin on Windows download setup.exe from
2880 \begin_inset LatexCommand \url[www.cygwin.com]{http://www.cygwin.com/}
2886 \begin_inset Quotes sld
2889 default text file type
2890 \begin_inset Quotes srd
2894 \begin_inset Quotes sld
2898 \begin_inset Quotes srd
2901 and download/install at least the following packages.
2902 Some packages are selected by default, others will be automatically selected
2903 because of dependencies with the manually selected packages.
2904 Never deselect these packages!
2913 gcc ; version 3.x is fine, no need to use the old 2.9x
2916 binutils ; selected with gcc
2922 rxvt ; a nice console, which makes life much easier under windoze (see below)
2925 man ; not really needed for building SDCC, but you'll miss it sooner or
2929 less ; not really needed for building SDCC, but you'll miss it sooner or
2933 cvs ; only if you use CVS access
2936 If you want to develop something you'll need:
2939 python ; for the regression tests
2942 gdb ; the gnu debugger, together with the nice GUI
2943 \begin_inset Quotes sld
2947 \begin_inset Quotes srd
2953 openssh ; to access the CF or commit changes
2956 autoconf and autoconf-devel ; if you want to fight with 'configure', don't
2957 use autoconf-stable!
2960 rxvt is a nice console with history.
2961 Replace in your cygwin.bat the line
2970 rxvt -sl 1000 -fn "Lucida Console-12" -sr -cr red
2973 -bg black -fg white -geometry 100x65 -e bash --login
2976 Text selected with the mouse is automatically copied to the clipboard, pasting
2977 works with shift-insert.
2981 The other good tip is to make sure you have no //c/-style paths anywhere,
2982 use /cygdrive/c/ instead.
2983 Using // invokes a network lookup which is very slow.
2985 \begin_inset Quotes sld
2989 \begin_inset Quotes srd
2992 is too long, you can change it with e.g.
2998 SDCC sources use the unix line ending LF.
2999 Life is much easier, if you store the source tree on a drive, which is
3000 mount in binary mode.
3001 And use an editor which can handle LF-only line endings.
3002 Make sure not to commit files with windows line endings.
3003 \layout Subsubsection
3005 Windows Install Using Microsoft Visual C++ 6.0/NET
3010 Download the source package
3012 either from the SDCC CVS repository or from the
3013 \begin_inset LatexCommand \url[nightly snapshots]{http://sdcc.sourceforge.net/snap.php}
3019 , it will be named something like sdcc
3026 SDCC is distributed with all the projects, workspaces, and files you need
3027 to build it using Visual C++ 6.0/NET.
3028 The workspace name is 'sdcc.dsw'.
3029 Please note that as it is now, all the executables are created in a folder
3033 Once built you need to copy the executables from sdcc
3037 bin before runnng SDCC.
3042 In order to build SDCC with Visual C++ 6.0/NET you need win32 executables
3043 of bison.exe, flex.exe, and gawk.exe.
3044 One good place to get them is
3045 \begin_inset LatexCommand \url[here]{http://unxutils.sourceforge.net}
3053 Download the file UnxUtils
3054 \begin_inset LatexCommand \index{UnxUtils}
3059 Now you have to install the utilities and setup Visual C++ so it can locate
3060 the required programs.
3061 Here there are two alternatives (choose one!):
3068 a) Extract UnxUtils.zip to your C:
3070 hard disk PRESERVING the original paths, otherwise bison won't work.
3071 (If you are using WinZip make certain that 'Use folder names' is selected)
3075 b) In the Visual C++ IDE click Tools, Options, select the Directory tab,
3076 in 'Show directories for:' select 'Executable files', and in the directories
3077 window add a new path: 'C:
3087 (As a side effect, you get a bunch of Unix utilities that could be useful,
3088 such as diff and patch.)
3095 This one avoids extracting a bunch of files you may not use, but requires
3100 a) Create a directory were to put the tools needed, or use a directory already
3108 b) Extract 'bison.exe', 'bison.hairy', 'bison.simple', 'flex.exe', and gawk.exe
3109 to such directory WITHOUT preserving the original paths.
3110 (If you are using WinZip make certain that 'Use folder names' is not selected)
3114 c) Rename bison.exe to '_bison.exe'.
3118 d) Create a batch file 'bison.bat' in 'C:
3122 ' and add these lines:
3142 _bison %1 %2 %3 %4 %5 %6 %7 %8 %9
3146 Steps 'c' and 'd' are needed because bison requires by default that the
3147 files 'bison.simple' and 'bison.hairy' reside in some weird Unix directory,
3148 '/usr/local/share/' I think.
3149 So it is necessary to tell bison where those files are located if they
3150 are not in such directory.
3151 That is the function of the environment variables BISON_SIMPLE and BISON_HAIRY.
3155 e) In the Visual C++ IDE click Tools, Options, select the Directory tab,
3156 in 'Show directories for:' select 'Executable files', and in the directories
3157 window add a new path: 'c:
3160 Note that you can use any other path instead of 'c:
3162 util', even the path where the Visual C++ tools are, probably: 'C:
3166 Microsoft Visual Studio
3171 So you don't have to execute step 'e' :)
3175 Open 'sdcc.dsw' in Visual Studio, click 'build all', when it finishes copy
3176 the executables from sdcc
3180 bin, and you can compile using sdcc.
3181 \layout Subsubsection
3183 Windows Install Using Borland
3186 From the sdcc directory, run the command "make -f Makefile.bcc".
3187 This should regenerate all the .exe files in the bin directory except for
3188 sdcdb.exe (which currently doesn't build under Borland C++).
3191 If you modify any source files and need to rebuild, be aware that the dependanci
3192 es may not be correctly calculated.
3193 The safest option is to delete all .obj files and run the build again.
3194 From a Cygwin BASH prompt, this can easily be done with the commmand:
3204 ( -name '*.obj' -o -name '*.lib' -o -name '*.rul'
3206 ) -print -exec rm {}
3215 or on Windows NT/2000/XP from the command prompt with the commmand:
3222 del /s *.obj *.lib *.rul
3225 from the sdcc directory.
3228 Building the Documentation
3235 Testing out the SDCC Compiler
3238 The first thing you should do after installing your SDCC compiler is to
3254 \begin_inset LatexCommand \index{version}
3261 at the prompt, and the program should run and tell you the version.
3262 If it doesn't run, or gives a message about not finding sdcc program, then
3263 you need to check over your installation.
3264 Make sure that the sdcc bin directory is in your executable search path
3265 defined by the PATH environment setting (see the Trouble-shooting section
3267 Make sure that the sdcc program is in the bin folder, if not perhaps something
3268 did not install correctly.
3276 is commonly installed as described in section
3277 \begin_inset Quotes sld
3280 Install and search paths
3281 \begin_inset Quotes srd
3290 Make sure the compiler works on a very simple example.
3291 Type in the following test.c program using your favorite
3326 Compile this using the following command:
3335 If all goes well, the compiler will generate a test.asm and test.rel file.
3336 Congratulations, you've just compiled your first program with SDCC.
3337 We used the -c option to tell SDCC not to link the generated code, just
3338 to keep things simple for this step.
3346 The next step is to try it with the linker.
3356 If all goes well the compiler will link with the libraries and produce
3357 a test.ihx output file.
3362 (no test.ihx, and the linker generates warnings), then the problem is most
3363 likely that sdcc cannot find the
3367 usr/local/share/sdcc/lib directory
3371 (see the Install trouble-shooting section for suggestions).
3379 The final test is to ensure sdcc can use the
3383 header files and libraries.
3384 Edit test.c and change it to the following:
3404 strcpy(str1, "testing");
3413 Compile this by typing
3420 This should generate a test.ihx output file, and it should give no warnings
3421 such as not finding the string.h file.
3422 If it cannot find the string.h file, then the problem is that sdcc cannot
3423 find the /usr/local/share/sdcc/include directory
3427 (see the Install trouble-shooting section for suggestions).
3430 Install Trouble-shooting
3431 \begin_inset LatexCommand \index{Install trouble-shooting}
3436 \layout Subsubsection
3438 SDCC does not build correctly.
3441 A thing to try is starting from scratch by unpacking the .tgz source package
3442 again in an empty directory.
3450 ./configure 2>&1 | tee configure.log
3464 make 2>&1 | tee make.log
3471 If anything goes wrong, you can review the log files to locate the problem.
3472 Or a relevant part of this can be attached to an email that could be helpful
3473 when requesting help from the mailing list.
3474 \layout Subsubsection
3477 \begin_inset Quotes sld
3481 \begin_inset Quotes srd
3488 \begin_inset Quotes sld
3492 \begin_inset Quotes srd
3495 command is a script that analyzes your system and performs some configuration
3496 to ensure the source package compiles on your system.
3497 It will take a few minutes to run, and will compile a few tests to determine
3498 what compiler features are installed.
3499 \layout Subsubsection
3502 \begin_inset Quotes sld
3506 \begin_inset Quotes srd
3512 This runs the GNU make tool, which automatically compiles all the source
3513 packages into the final installed binary executables.
3514 \layout Subsubsection
3517 \begin_inset Quotes sld
3521 \begin_inset Quotes erd
3527 This will install the compiler, other executables libraries and include
3528 files in to the appropriate directories.
3530 \begin_inset Quotes sld
3533 Install and Search PATHS
3534 \begin_inset Quotes srd
3539 On most systems you will need super-user privilages to do this.
3545 SDCC is not just a compiler, but a collection of tools by various developers.
3546 These include linkers, assemblers, simulators and other components.
3547 Here is a summary of some of the components.
3548 Note that the included simulator and assembler have separate documentation
3549 which you can find in the source package in their respective directories.
3550 As SDCC grows to include support for other processors, other packages from
3551 various developers are included and may have their own sets of documentation.
3555 You might want to look at the files which are installed in <installdir>.
3556 At the time of this writing, we find the following programs for gcc-builds:
3560 In <installdir>/bin:
3563 sdcc - The compiler.
3566 sdcpp - The C preprocessor.
3569 asx8051 - The assembler for 8051 type processors.
3576 as-gbz80 - The Z80 and GameBoy Z80 assemblers.
3579 aslink -The linker for 8051 type processors.
3586 link-gbz80 - The Z80 and GameBoy Z80 linkers.
3589 s51 - The ucSim 8051 simulator.
3592 sdcdb - The source debugger.
3595 packihx - A tool to pack (compress) Intel hex files.
3598 In <installdir>/share/sdcc/include
3604 In <installdir>/share/sdcc/lib
3607 the subdirs src and small, large, z80, gbz80 and ds390 with the precompiled
3611 In <installdir>/share/sdcc/doc
3617 As development for other processors proceeds, this list will expand to include
3618 executables to support processors like AVR, PIC, etc.
3619 \layout Subsubsection
3624 This is the actual compiler, it in turn uses the c-preprocessor and invokes
3625 the assembler and linkage editor.
3626 \layout Subsubsection
3629 \begin_inset LatexCommand \index{sdcpp}
3633 - The C-Preprocessor
3636 The preprocessor is a modified version of the GNU preprocessor.
3637 The C preprocessor is used to pull in #include sources, process #ifdef
3638 statements, #defines and so on.
3639 \layout Subsubsection
3641 asx8051, as-z80, as-gbz80, aslink, link-z80, link-gbz80 - The Assemblers
3645 This is retargettable assembler & linkage editor, it was developed by Alan
3647 John Hartman created the version for 8051, and I (Sandeep) have made some
3648 enhancements and bug fixes for it to work properly with the SDCC.
3649 \layout Subsubsection
3652 \begin_inset LatexCommand \index{s51}
3659 S51 is a freeware, opensource simulator developed by Daniel Drotos (
3660 \begin_inset LatexCommand \url{mailto:drdani@mazsola.iit.uni-miskolc.hu}
3665 The simulator is built as part of the build process.
3666 For more information visit Daniel's website at:
3667 \begin_inset LatexCommand \url{http://mazsola.iit.uni-miskolc.hu/~drdani/embedded/s51}
3672 It currently support the core mcs51, the Dallas DS80C390 and the Philips
3674 \layout Subsubsection
3677 \begin_inset LatexCommand \index{sdcdb}
3681 - Source Level Debugger
3684 Sdcdb is the companion source level debugger.
3685 The current version of the debugger uses Daniel's Simulator S51, but can
3686 be easily changed to use other simulators.
3693 \layout Subsubsection
3695 Single Source File Projects
3698 For single source file 8051 projects the process is very simple.
3699 Compile your programs with the following command
3702 "sdcc sourcefile.c".
3706 This will compile, assemble and link your source file.
3707 Output files are as follows
3711 \begin_inset LatexCommand \index{.asm}
3716 \begin_inset LatexCommand \index{Assembler source}
3720 file created by the compiler
3724 \begin_inset LatexCommand \index{.lst}
3729 \begin_inset LatexCommand \index{Assembler listing}
3733 file created by the Assembler
3737 \begin_inset LatexCommand \index{.rst}
3742 \begin_inset LatexCommand \index{Assembler listing}
3746 file updated with linkedit information, created by linkage editor
3750 \begin_inset LatexCommand \index{.sym}
3755 \begin_inset LatexCommand \index{Symbol listing}
3759 for the sourcefile, created by the assembler
3763 \begin_inset LatexCommand \index{.rel}
3768 \begin_inset LatexCommand \index{Object file}
3772 created by the assembler, input to Linkage editor
3776 \begin_inset LatexCommand \index{.map}
3781 \begin_inset LatexCommand \index{Memory map}
3785 for the load module, created by the Linker
3789 \begin_inset LatexCommand \index{.mem}
3793 - A file with a summary of the memory usage
3797 \begin_inset LatexCommand \index{.ihx}
3801 - The load module in Intel hex format
3802 \begin_inset LatexCommand \index{Intel hex format}
3806 (you can select the Motorola S19 format
3807 \begin_inset LatexCommand \index{Motorola S19 format}
3822 \begin_inset LatexCommand \index{-\/-out-fmt-s19}
3827 If you need another format you might want to use objdump
3828 \begin_inset LatexCommand \index{objdump}
3833 \begin_inset LatexCommand \index{srecord}
3841 \begin_inset LatexCommand \index{.adb}
3845 - An intermediate file containing debug information needed to create the
3857 \begin_inset LatexCommand \index{-\/-debug}
3865 \begin_inset LatexCommand \index{.cdb}
3869 - An optional file (with -
3879 -debug) containing debug information
3884 \begin_inset LatexCommand \index{. (no extension)}
3888 An optional AOMF51 file containing debug information (with -
3902 \begin_inset LatexCommand \index{.dump*}
3906 - Dump file to debug the compiler it self (with -
3916 -dumpall) (see section
3917 \begin_inset Quotes sld
3920 Anatomy of the compiler
3921 \begin_inset Quotes srd
3925 \layout Subsubsection
3927 Projects with Multiple Source Files
3930 SDCC can compile only ONE file at a time.
3931 Let us for example assume that you have a project containing the following
3936 foo1.c (contains some functions)
3938 foo2.c (contains some more functions)
3940 foomain.c (contains more functions and the function main)
3948 The first two files will need to be compiled separately with the commands:
3980 Then compile the source file containing the
3985 \begin_inset LatexCommand \index{Linker}
3989 the files together with the following command:
3997 foomain.c\SpecialChar ~
3998 foo1.rel\SpecialChar ~
4003 \begin_inset LatexCommand \index{.rel}
4015 can be separately compiled as well:
4026 sdcc foomain.rel foo1.rel foo2.rel
4033 The file containing the
4048 file specified in the command line, since the linkage editor processes
4049 file in the order they are presented to it.
4050 \layout Subsubsection
4052 Projects with Additional Libraries
4053 \begin_inset LatexCommand \index{Libraries}
4060 Some reusable routines may be compiled into a library, see the documentation
4061 for the assembler and linkage editor (which are in <installdir>/share/sdcc/doc)
4065 \begin_inset LatexCommand \index{.lib}
4072 Libraries created in this manner can be included in the command line.
4073 Make sure you include the -L <library-path> option to tell the linker where
4074 to look for these files if they are not in the current directory.
4075 Here is an example, assuming you have the source file
4087 (if that is not the same as your current project):
4094 sdcc foomain.c foolib.lib -L mylib
4105 must be an absolute path name.
4109 The most efficient way to use libraries is to keep seperate modules in seperate
4111 The lib file now should name all the modules.rel files.
4112 For an example see the standard library file
4116 in the directory <installdir>/share/lib/small.
4119 Command Line Options
4120 \begin_inset LatexCommand \index{Command Line Options}
4125 \layout Subsubsection
4127 Processor Selection Options
4128 \begin_inset LatexCommand \index{Options processor selection}
4133 \begin_inset LatexCommand \index{Processor selection options}
4139 \labelwidthstring 00.00.0000
4144 \begin_inset LatexCommand \index{-mmcs51}
4150 Generate code for the MCS51
4151 \begin_inset LatexCommand \index{MCS51}
4155 family of processors.
4156 This is the default processor target.
4158 \labelwidthstring 00.00.0000
4163 \begin_inset LatexCommand \index{-mds390}
4169 Generate code for the DS80C390
4170 \begin_inset LatexCommand \index{DS80C390}
4176 \labelwidthstring 00.00.0000
4181 \begin_inset LatexCommand \index{-mds400}
4187 Generate code for the DS80C400
4188 \begin_inset LatexCommand \index{DS80C400}
4194 \labelwidthstring 00.00.0000
4199 \begin_inset LatexCommand \index{-mz80}
4205 Generate code for the Z80
4206 \begin_inset LatexCommand \index{Z80}
4210 family of processors.
4212 \labelwidthstring 00.00.0000
4217 \begin_inset LatexCommand \index{-mgbz80}
4223 Generate code for the GameBoy Z80
4224 \begin_inset LatexCommand \index{GameBoy Z80}
4230 \labelwidthstring 00.00.0000
4235 \begin_inset LatexCommand \index{-mavr}
4241 Generate code for the Atmel AVR
4242 \begin_inset LatexCommand \index{AVR}
4246 processor (In development, not complete).
4247 AVR users should probably have a look at avr-gcc
4248 \begin_inset LatexCommand \url[FIXME: official URL?]{ http://savannah.nongnu.org/download/avr-libc/snapshots/}
4255 I think it is fair to direct users there for now.
4256 Open source is also about avoiding unnecessary work .
4257 But I didn't find the 'official' link.
4259 \labelwidthstring 00.00.0000
4264 \begin_inset LatexCommand \index{-mpic14}
4270 Generate code for the PIC 14
4271 \begin_inset LatexCommand \index{PIC14}
4275 -bit processors (In development, not complete).
4278 p16f627 p16f628 p16f84 p16f873 p16f877?
4280 \labelwidthstring 00.00.0000
4286 Generate code for the Toshiba TLCS-900H
4287 \begin_inset LatexCommand \index{TLCS-900H}
4291 processor (In development, not complete).
4293 \labelwidthstring 00.00.0000
4298 \begin_inset LatexCommand \index{-mxa51}
4304 Generate code for the Philips XA51
4305 \begin_inset LatexCommand \index{XA51}
4309 processor (In development, not complete).
4310 \layout Subsubsection
4312 Preprocessor Options
4313 \begin_inset LatexCommand \index{Options preprocessor}
4318 \begin_inset LatexCommand \index{Preprocessor options}
4324 \labelwidthstring 00.00.0000
4329 \begin_inset LatexCommand \index{-I<path>}
4335 The additional location where the pre processor will look for <..h> or
4336 \begin_inset Quotes eld
4340 \begin_inset Quotes erd
4345 \labelwidthstring 00.00.0000
4350 \begin_inset LatexCommand \index{-D<macro[=value]>}
4356 Command line definition of macros.
4357 Passed to the pre processor.
4359 \labelwidthstring 00.00.0000
4364 \begin_inset LatexCommand \index{-M}
4370 Tell the preprocessor to output a rule suitable for make describing the
4371 dependencies of each object file.
4372 For each source file, the preprocessor outputs one make-rule whose target
4373 is the object file name for that source file and whose dependencies are
4374 all the files `#include'd in it.
4375 This rule may be a single line or may be continued with `
4377 '-newline if it is long.
4378 The list of rules is printed on standard output instead of the preprocessed
4382 \labelwidthstring 00.00.0000
4387 \begin_inset LatexCommand \index{-C}
4393 Tell the preprocessor not to discard comments.
4394 Used with the `-E' option.
4396 \labelwidthstring 00.00.0000
4401 \begin_inset LatexCommand \index{-MM}
4412 Like `-M' but the output mentions only the user header files included with
4414 \begin_inset Quotes eld
4418 System header files included with `#include <file>' are omitted.
4420 \labelwidthstring 00.00.0000
4425 \begin_inset LatexCommand \index{-Aquestion(answer)}
4431 Assert the answer answer for question, in case it is tested with a preprocessor
4432 conditional such as `#if #question(answer)'.
4433 `-A-' disables the standard assertions that normally describe the target
4436 \labelwidthstring 00.00.0000
4442 (answer) Assert the answer answer for question, in case it is tested with
4443 a preprocessor conditional such as `#if #question(answer)'.
4444 `-A-' disables the standard assertions that normally describe the target
4447 \labelwidthstring 00.00.0000
4452 \begin_inset LatexCommand \index{-Umacro}
4458 Undefine macro macro.
4459 `-U' options are evaluated after all `-D' options, but before any `-include'
4460 and `-imacros' options.
4462 \labelwidthstring 00.00.0000
4467 \begin_inset LatexCommand \index{-dM}
4473 Tell the preprocessor to output only a list of the macro definitions that
4474 are in effect at the end of preprocessing.
4475 Used with the `-E' option.
4477 \labelwidthstring 00.00.0000
4482 \begin_inset LatexCommand \index{-dD}
4488 Tell the preprocessor to pass all macro definitions into the output, in
4489 their proper sequence in the rest of the output.
4491 \labelwidthstring 00.00.0000
4496 \begin_inset LatexCommand \index{-dN}
4507 Like `-dD' except that the macro arguments and contents are omitted.
4508 Only `#define name' is included in the output.
4509 \layout Subsubsection
4512 \begin_inset LatexCommand \index{Options linker}
4517 \begin_inset LatexCommand \index{Linker options}
4523 \labelwidthstring 00.00.0000
4543 \begin_inset LatexCommand \index{-\/-lib-path}
4548 \begin_inset LatexCommand \index{-L -\/-lib-path}
4557 <absolute path to additional libraries> This option is passed to the linkage
4558 editor's additional libraries
4559 \begin_inset LatexCommand \index{Libraries}
4564 The path name must be absolute.
4565 Additional library files may be specified in the command line.
4566 See section Compiling programs for more details.
4568 \labelwidthstring 00.00.0000
4585 \begin_inset LatexCommand \index{-\/-xram-loc}
4589 <Value> The start location of the external ram
4590 \begin_inset LatexCommand \index{xdata}
4594 , default value is 0.
4595 The value entered can be in Hexadecimal or Decimal format, e.g.: -
4605 -xram-loc 0x8000 or -
4617 \labelwidthstring 00.00.0000
4634 \begin_inset LatexCommand \index{-\/-code-loc}
4638 <Value> The start location of the code
4639 \begin_inset LatexCommand \index{code}
4643 segment, default value 0.
4644 Note when this option is used the interrupt vector table is also relocated
4645 to the given address.
4646 The value entered can be in Hexadecimal or Decimal format, e.g.: -
4656 -code-loc 0x8000 or -
4668 \labelwidthstring 00.00.0000
4685 \begin_inset LatexCommand \index{-\/-stack-loc}
4689 <Value> By default the stack
4690 \begin_inset LatexCommand \index{stack}
4694 is placed after the data segment.
4695 Using this option the stack can be placed anywhere in the internal memory
4697 The value entered can be in Hexadecimal or Decimal format, e.g.
4708 -stack-loc 0x20 or -
4719 Since the sp register is incremented before a push or call, the initial
4720 sp will be set to one byte prior the provided value.
4721 The provided value should not overlap any other memory areas such as used
4722 register banks or the data segment and with enough space for the current
4725 \labelwidthstring 00.00.0000
4742 \begin_inset LatexCommand \index{-\/-data-loc}
4746 <Value> The start location of the internal ram data
4747 \begin_inset LatexCommand \index{data}
4752 The value entered can be in Hexadecimal or Decimal format, eg.
4774 (By default, the start location of the internal ram data segment is set
4775 as low as possible in memory, taking into account the used register banks
4776 and the bit segment at address 0x20.
4777 For example if register banks 0 and 1 are used without bit variables, the
4778 data segment will be set, if -
4788 -data-loc is not used, to location 0x10.)
4790 \labelwidthstring 00.00.0000
4807 \begin_inset LatexCommand \index{-\/-idata-loc}
4811 <Value> The start location of the indirectly addressable internal ram
4812 \begin_inset LatexCommand \index{idata}
4816 , default value is 0x80.
4817 The value entered can be in Hexadecimal or Decimal format, eg.
4828 -idata-loc 0x88 or -
4840 \labelwidthstring 00.00.0000
4855 \begin_inset LatexCommand \index{-\/-out-fmt-ihx}
4864 The linker output (final object code) is in Intel Hex format.
4865 \begin_inset LatexCommand \index{Intel hex format}
4869 (This is the default option).
4871 \labelwidthstring 00.00.0000
4886 \begin_inset LatexCommand \index{-\/-out-fmt-s19}
4895 The linker output (final object code) is in Motorola S19 format
4896 \begin_inset LatexCommand \index{Motorola S19 format}
4901 \layout Subsubsection
4904 \begin_inset LatexCommand \index{Options MCS51}
4909 \begin_inset LatexCommand \index{MCS51 options}
4915 \labelwidthstring 00.00.0000
4930 \begin_inset LatexCommand \index{-\/-model-large}
4936 Generate code for Large model programs see section Memory Models for more
4938 If this option is used all source files in the project should be compiled
4940 In addition the standard library routines are compiled with small model,
4941 they will need to be recompiled.
4943 \labelwidthstring 00.00.0000
4958 \begin_inset LatexCommand \index{-\/-model-small}
4969 Generate code for Small Model programs see section Memory Models for more
4971 This is the default model.
4972 \layout Subsubsection
4975 \begin_inset LatexCommand \index{Options DS390}
4980 \begin_inset LatexCommand \index{DS390 options}
4986 \labelwidthstring 00.00.0000
5003 \begin_inset LatexCommand \index{-\/-model-flat24}
5013 Generate 24-bit flat mode code.
5014 This is the one and only that the ds390 code generator supports right now
5015 and is default when using
5020 See section Memory Models for more details.
5022 \labelwidthstring 00.00.0000
5039 \begin_inset LatexCommand \index{-\/-stack-10bit}
5043 Generate code for the 10 bit stack mode of the Dallas DS80C390 part.
5044 This is the one and only that the ds390 code generator supports right now
5045 and is default when using
5050 In this mode, the stack is located in the lower 1K of the internal RAM,
5051 which is mapped to 0x400000.
5052 Note that the support is incomplete, since it still uses a single byte
5053 as the stack pointer.
5054 This means that only the lower 256 bytes of the potential 1K stack space
5055 will actually be used.
5056 However, this does allow you to reclaim the precious 256 bytes of low RAM
5057 for use for the DATA and IDATA segments.
5058 The compiler will not generate any code to put the processor into 10 bit
5060 It is important to ensure that the processor is in this mode before calling
5061 any re-entrant functions compiled with this option.
5062 In principle, this should work with the
5075 \begin_inset LatexCommand \index{-\/-stack-auto}
5081 option, but that has not been tested.
5082 It is incompatible with the
5095 \begin_inset LatexCommand \index{-\/-xstack}
5102 It also only makes sense if the processor is in 24 bit contiguous addressing
5115 -model-flat24 option
5118 \layout Subsubsection
5120 Optimization Options
5121 \begin_inset LatexCommand \index{Options optimization}
5126 \begin_inset LatexCommand \index{Optimization options}
5132 \labelwidthstring 00.00.0000
5147 \begin_inset LatexCommand \index{-\/-nogcse}
5153 Will not do global subexpression elimination, this option may be used when
5154 the compiler creates undesirably large stack/data spaces to store compiler
5156 A warning message will be generated when this happens and the compiler
5157 will indicate the number of extra bytes it allocated.
5158 It recommended that this option NOT be used, #pragma\SpecialChar ~
5160 \begin_inset LatexCommand \index{\#pragma NOGCSE}
5164 can be used to turn off global subexpression elimination
5165 \begin_inset LatexCommand \index{Subexpression elimination}
5169 for a given function only.
5171 \labelwidthstring 00.00.0000
5186 \begin_inset LatexCommand \index{-\/-noinvariant}
5192 Will not do loop invariant optimizations, this may be turned off for reasons
5193 explained for the previous option.
5194 For more details of loop optimizations performed see section Loop Invariants.It
5195 recommended that this option NOT be used, #pragma\SpecialChar ~
5197 \begin_inset LatexCommand \index{\#pragma NOINVARIANT}
5201 can be used to turn off invariant optimizations for a given function only.
5203 \labelwidthstring 00.00.0000
5218 \begin_inset LatexCommand \index{-\/-noinduction}
5224 Will not do loop induction optimizations, see section strength reduction
5225 for more details.It is recommended that this option is NOT used, #pragma\SpecialChar ~
5228 \begin_inset LatexCommand \index{\#pragma NOINDUCTION}
5232 can be used to turn off induction optimizations for a given function only.
5234 \labelwidthstring 00.00.0000
5249 \begin_inset LatexCommand \index{-\/-nojtbound}
5260 Will not generate boundary condition check when switch statements
5261 \begin_inset LatexCommand \index{switch statement}
5265 are implemented using jump-tables.
5266 See section Switch Statements for more details.
5267 It is recommended that this option is NOT used, #pragma\SpecialChar ~
5269 \begin_inset LatexCommand \index{\#pragma NOJTBOUND}
5273 can be used to turn off boundary checking for jump tables for a given function
5276 \labelwidthstring 00.00.0000
5291 \begin_inset LatexCommand \index{-\/-noloopreverse}
5300 Will not do loop reversal
5301 \begin_inset LatexCommand \index{Loop reversing}
5307 \labelwidthstring 00.00.0000
5324 \begin_inset LatexCommand \index{-\/-nolabelopt }
5328 Will not optimize labels (makes the dumpfiles more readable).
5330 \labelwidthstring 00.00.0000
5345 \begin_inset LatexCommand \index{-\/-no-xinit-opt}
5351 Will not memcpy initialized data in far space from code space.
5352 This saves a few bytes in code space if you don't have initialized data.
5353 \layout Subsubsection
5356 \begin_inset LatexCommand \index{Options other}
5362 \labelwidthstring 00.00.0000
5378 \begin_inset LatexCommand \index{-\/-compile-only}
5383 \begin_inset LatexCommand \index{-c -\/-compile-only}
5389 will compile and assemble the source, but will not call the linkage editor.
5391 \labelwidthstring 00.00.0000
5410 \begin_inset LatexCommand \index{-\/-c1mode}
5416 reads the preprocessed source from standard input and compiles it.
5417 The file name for the assembler output must be specified using the -o option.
5419 \labelwidthstring 00.00.0000
5424 \begin_inset LatexCommand \index{-E}
5430 Run only the C preprocessor.
5431 Preprocess all the C source files specified and output the results to standard
5434 \labelwidthstring 00.00.0000
5440 \begin_inset LatexCommand \index{-o <path/file>}
5446 The output path resp.
5447 file where everything will be placed.
5448 If the parameter is a path, it must have a trailing slash (or backslash
5449 for the Windows binaries) to be recognized as a path.
5452 \labelwidthstring 00.00.0000
5467 \begin_inset LatexCommand \index{-\/-stack-auto}
5478 All functions in the source file will be compiled as
5483 \begin_inset LatexCommand \index{reentrant}
5488 the parameters and local variables will be allocated on the stack
5489 \begin_inset LatexCommand \index{stack}
5494 see section Parameters and Local Variables for more details.
5495 If this option is used all source files in the project should be compiled
5499 \labelwidthstring 00.00.0000
5514 \begin_inset LatexCommand \index{-\/-xstack}
5520 Uses a pseudo stack in the first 256 bytes in the external ram for allocating
5521 variables and passing parameters.
5522 See section on external stack for more details.
5524 \labelwidthstring 00.00.0000
5539 \begin_inset LatexCommand \index{-\/-callee-saves}
5544 \begin_inset LatexCommand \index{function prologue}
5548 function1[,function2][,function3]....
5551 The compiler by default uses a caller saves convention for register saving
5552 across function calls, however this can cause unneccessary register pushing
5553 & popping when calling small functions from larger functions.
5554 This option can be used to switch the register saving convention for the
5555 function names specified.
5556 The compiler will not save registers when calling these functions, no extra
5557 code will be generated at the entry & exit for these functions to save
5558 & restore the registers used by these functions, this can SUBSTANTIALLY
5559 reduce code & improve run time performance of the generated code.
5560 In the future the compiler (with interprocedural analysis) will be able
5561 to determine the appropriate scheme to use for each function call.
5562 DO NOT use this option for built-in functions such as _mulint..., if this
5563 option is used for a library function the appropriate library function
5564 needs to be recompiled with the same option.
5565 If the project consists of multiple source files then all the source file
5566 should be compiled with the same -
5576 -callee-saves option string.
5577 Also see #pragma\SpecialChar ~
5579 \begin_inset LatexCommand \index{\#pragma CALLEE-SAVES}
5585 \labelwidthstring 00.00.0000
5600 \begin_inset LatexCommand \index{-\/-debug}
5609 When this option is used the compiler will generate debug information, that
5610 can be used with the SDCDB.
5611 The debug information is collected in a file with .cdb extension.
5612 For more information see documentation for SDCDB.
5614 \labelwidthstring 00.00.0000
5631 \begin_inset LatexCommand \index{-\/-peep-file}
5635 <filename> This option can be used to use additional rules to be used by
5636 the peep hole optimizer.
5637 See section Peep Hole optimizations for details on how to write these rules.
5639 \labelwidthstring 00.00.0000
5644 \begin_inset LatexCommand \index{-S}
5655 Stop after the stage of compilation proper; do not assemble.
5656 The output is an assembler code file for the input file specified.
5658 \labelwidthstring 00.00.0000
5662 -Wa_asmOption[,asmOption]
5665 \begin_inset LatexCommand \index{-Wa\_asmOption[,asmOption]}
5670 Pass the asmOption to the assembler.
5672 \labelwidthstring 00.00.0000
5676 -Wl_linkOption[,linkOption]
5679 \begin_inset LatexCommand \index{-Wl\_linkOption[,linkOption]}
5684 Pass the linkOption to the linker.
5686 \labelwidthstring 00.00.0000
5701 \begin_inset LatexCommand \index{-\/-int-long-reent}
5707 Integer (16 bit) and long (32 bit) libraries have been compiled as reentrant.
5708 Note by default these libraries are compiled as non-reentrant.
5709 See section Installation for more details.
5711 \labelwidthstring 00.00.0000
5726 \begin_inset LatexCommand \index{-\/-cyclomatic}
5735 This option will cause the compiler to generate an information message for
5736 each function in the source file.
5737 The message contains some
5741 information about the function.
5742 The number of edges and nodes the compiler detected in the control flow
5743 graph of the function, and most importantly the
5745 cyclomatic complexity
5746 \begin_inset LatexCommand \index{Cyclomatic complexity}
5752 see section on Cyclomatic Complexity for more details.
5754 \labelwidthstring 00.00.0000
5769 \begin_inset LatexCommand \index{-\/-float-reent}
5778 Floating point library is compiled as reentrant
5779 \begin_inset LatexCommand \index{reentrant}
5783 .See section Installation for more details.
5785 \labelwidthstring 00.00.0000
5800 \begin_inset LatexCommand \index{-\/-nooverlay}
5806 The compiler will not overlay parameters and local variables of any function,
5807 see section Parameters and local variables for more details.
5809 \labelwidthstring 00.00.0000
5824 \begin_inset LatexCommand \index{-\/-main-return}
5830 This option can be used when the code generated is called by a monitor
5832 The compiler will generate a 'ret' upon return from the 'main'
5833 \begin_inset LatexCommand \index{main return}
5838 The default option is to lock up i.e.
5841 \labelwidthstring 00.00.0000
5856 \begin_inset LatexCommand \index{-\/-no-peep}
5862 Disable peep-hole optimization.
5864 \labelwidthstring 00.00.0000
5879 \begin_inset LatexCommand \index{-\/-peep-asm}
5885 Pass the inline assembler code through the peep hole optimizer.
5886 This can cause unexpected changes to inline assembler code, please go through
5887 the peephole optimizer
5888 \begin_inset LatexCommand \index{Peephole optimizer}
5892 rules defined in the source file tree '<target>/peeph.def' before using
5895 \labelwidthstring 00.00.0000
5912 \begin_inset LatexCommand \index{-\/-iram-size<Value>}
5916 Causes the linker to check if the internal ram usage is within limits of
5919 \labelwidthstring 00.00.0000
5936 \begin_inset LatexCommand \index{-\/-xram-size<Value>}
5940 Causes the linker to check if the external ram usage is within limits of
5943 \labelwidthstring 00.00.0000
5960 \begin_inset LatexCommand \index{-\/-code-size<Value>}
5964 Causes the linker to check if the code usage is within limits of the given
5967 \labelwidthstring 00.00.0000
5982 \begin_inset LatexCommand \index{-\/-nostdincl}
5988 This will prevent the compiler from passing on the default include path
5989 to the preprocessor.
5991 \labelwidthstring 00.00.0000
6006 \begin_inset LatexCommand \index{-\/-nostdlib}
6012 This will prevent the compiler from passing on the default library
6013 \begin_inset LatexCommand \index{Libraries}
6019 \labelwidthstring 00.00.0000
6034 \begin_inset LatexCommand \index{-\/-verbose}
6040 Shows the various actions the compiler is performing.
6042 \labelwidthstring 00.00.0000
6047 \begin_inset LatexCommand \index{-V}
6053 Shows the actual commands the compiler is executing.
6055 \labelwidthstring 00.00.0000
6070 \begin_inset LatexCommand \index{-\/-no-c-code-in-asm}
6076 Hides your ugly and inefficient c-code from the asm file, so you can always
6077 blame the compiler :).
6079 \labelwidthstring 00.00.0000
6094 \begin_inset LatexCommand \index{-\/-i-code-in-asm}
6100 Include i-codes in the asm file.
6101 Sounds like noise but is most helpfull for debugging the compiler itself.
6103 \labelwidthstring 00.00.0000
6118 \begin_inset LatexCommand \index{-\/-less-pedantic}
6124 Disable some of the more pedantic warnings (jwk burps: please be more specific
6127 \labelwidthstring 00.00.0000
6142 \begin_inset LatexCommand \index{-\/-print-search-dirs}
6148 Display the directories in the compiler's search path
6149 \layout Subsubsection
6151 Intermediate Dump Options
6152 \begin_inset LatexCommand \index{Options intermediate dump}
6157 \begin_inset LatexCommand \index{Intermediate dump options}
6164 The following options are provided for the purpose of retargetting and debugging
6166 These provided a means to dump the intermediate code (iCode
6167 \begin_inset LatexCommand \index{iCode}
6171 ) generated by the compiler in human readable form at various stages of
6172 the compilation process.
6175 \labelwidthstring 00.00.0000
6190 \begin_inset LatexCommand \index{-\/-dumpraw}
6196 This option will cause the compiler to dump the intermediate code into
6199 <source filename>.dumpraw
6201 just after the intermediate code has been generated for a function, i.e.
6202 before any optimizations are done.
6204 \begin_inset LatexCommand \index{Basic blocks}
6208 at this stage ordered in the depth first number, so they may not be in
6209 sequence of execution.
6211 \labelwidthstring 00.00.0000
6226 \begin_inset LatexCommand \index{-\/-dumpgcse}
6232 Will create a dump of iCode's, after global subexpression elimination
6233 \begin_inset LatexCommand \index{Global subexpression elimination}
6239 <source filename>.dumpgcse.
6241 \labelwidthstring 00.00.0000
6256 \begin_inset LatexCommand \index{-\/-dumpdeadcode}
6262 Will create a dump of iCode's, after deadcode elimination
6263 \begin_inset LatexCommand \index{Dead-code elimination}
6269 <source filename>.dumpdeadcode.
6271 \labelwidthstring 00.00.0000
6286 \begin_inset LatexCommand \index{-\/-dumploop}
6295 Will create a dump of iCode's, after loop optimizations
6296 \begin_inset LatexCommand \index{Loop optimization}
6302 <source filename>.dumploop.
6304 \labelwidthstring 00.00.0000
6319 \begin_inset LatexCommand \index{-\/-dumprange}
6328 Will create a dump of iCode's, after live range analysis
6329 \begin_inset LatexCommand \index{Live range analysis}
6335 <source filename>.dumprange.
6337 \labelwidthstring 00.00.0000
6352 \begin_inset LatexCommand \index{-\/-dumlrange}
6358 Will dump the life ranges
6359 \begin_inset LatexCommand \index{Live range analysis}
6365 \labelwidthstring 00.00.0000
6380 \begin_inset LatexCommand \index{-\/-dumpregassign}
6389 Will create a dump of iCode's, after register assignment
6390 \begin_inset LatexCommand \index{Register assignment}
6396 <source filename>.dumprassgn.
6398 \labelwidthstring 00.00.0000
6413 \begin_inset LatexCommand \index{-\/-dumplrange}
6419 Will create a dump of the live ranges of iTemp's
6421 \labelwidthstring 00.00.0000
6436 \begin_inset LatexCommand \index{-\/-dumpall}
6447 Will cause all the above mentioned dumps to be created.
6450 Environment variables
6451 \begin_inset LatexCommand \index{Environment variables}
6458 SDCC recognizes the following environment variables:
6460 \labelwidthstring 00.00.0000
6465 \begin_inset LatexCommand \index{SDCC\_LEAVE\_SIGNALS}
6471 SDCC installs a signal handler
6472 \begin_inset LatexCommand \index{signal handler}
6476 to be able to delete temporary files after an user break (^C) or an exception.
6477 If this environment variable is set, SDCC won't install the signal handler
6478 in order to be able to debug SDCC.
6480 \labelwidthstring 00.00.0000
6485 \begin_inset LatexCommand \index{TMP}
6491 \begin_inset LatexCommand \index{TEMP}
6497 \begin_inset LatexCommand \index{TMPDIR}
6503 Path, where temporary files will be created.
6504 The order of the variables is the search order.
6505 In a standard *nix environment these variables are not set, and there's
6506 no need to set them.
6507 On Windows it's recommended to set one of them.
6509 \labelwidthstring 00.00.0000
6514 \begin_inset LatexCommand \index{SDCC\_HOME}
6521 \begin_inset Quotes sld
6524 2.3 Install and search paths
6525 \begin_inset Quotes srd
6530 \labelwidthstring 00.00.0000
6535 \begin_inset LatexCommand \index{SDCC\_INCLUDE}
6542 \begin_inset Quotes sld
6545 2.3 Install and search paths
6546 \begin_inset Quotes srd
6551 \labelwidthstring 00.00.0000
6556 \begin_inset LatexCommand \index{SDCC\_LIB}
6563 \begin_inset Quotes sld
6566 2.3 Install and search paths
6567 \begin_inset Quotes srd
6573 There are some more environment variables recognized by SDCC, but these
6574 are solely used for debugging purposes.
6575 They can change or disappear very quickly, and will never be documentated.
6578 MCS51/DS390 Storage Class
6579 \begin_inset LatexCommand \index{Storage class}
6586 In addition to the ANSI storage classes SDCC allows the following MCS51
6587 specific storage classes.
6588 \layout Subsubsection
6591 \begin_inset LatexCommand \index{xdata}
6598 Variables declared with this storage class will be placed in the extern
6604 storage class for Large Memory model, e.g.:
6610 xdata unsigned char xduc;
6611 \layout Subsubsection
6614 \begin_inset LatexCommand \index{data}
6625 storage class for Small Memory model.
6626 Variables declared with this storage class will be allocated in the internal
6634 \layout Subsubsection
6637 \begin_inset LatexCommand \index{idata}
6644 Variables declared with this storage class will be allocated into the indirectly
6645 addressable portion of the internal ram of a 8051, e.g.:
6652 \layout Subsubsection
6655 \begin_inset LatexCommand \index{bit}
6662 This is a data-type and a storage class specifier.
6663 When a variable is declared as a bit, it is allocated into the bit addressable
6664 memory of 8051, e.g.:
6671 \layout Subsubsection
6674 \begin_inset LatexCommand \index{sfr}
6679 \begin_inset LatexCommand \index{sbit}
6686 Like the bit keyword,
6690 signifies both a data-type and storage class, they are used to describe
6691 the special function registers and special bit variables of a 8051, eg:
6697 sfr at 0x80 P0; /* special function register P0 at location 0x80 */
6699 sbit at 0xd7 CY; /* CY (Carry Flag
6700 \begin_inset LatexCommand \index{Flags}
6705 \begin_inset LatexCommand \index{Carry flag}
6713 \begin_inset LatexCommand \index{Pointers}
6720 SDCC allows (via language extensions) pointers to explicitly point to any
6721 of the memory spaces
6722 \begin_inset LatexCommand \index{Memory model}
6727 In addition to the explicit pointers, the compiler uses (by default) generic
6728 pointers which can be used to point to any of the memory spaces.
6732 Pointer declaration examples:
6741 /* pointer physically in xternal ram pointing to object in internal ram
6744 data unsigned char * xdata p;
6748 /* pointer physically in code rom pointing to data in xdata space */
6750 xdata unsigned char * code p;
6754 /* pointer physically in code space pointing to data in code space */
6756 code unsigned char * code p;
6760 /* the folowing is a generic pointer physically located in xdata space */
6771 Well you get the idea.
6776 All unqualified pointers are treated as 3-byte (4-byte for the ds390)
6789 The highest order byte of the
6793 pointers contains the data space information.
6794 Assembler support routines are called whenever data is stored or retrieved
6800 These are useful for developing reusable library
6801 \begin_inset LatexCommand \index{Libraries}
6806 Explicitly specifying the pointer type will generate the most efficient
6811 \begin_inset LatexCommand \index{Parameters}
6816 \begin_inset LatexCommand \index{Local variable}
6823 Automatic (local) variables and parameters to functions can either be placed
6824 on the stack or in data-space.
6825 The default action of the compiler is to place these variables in the internal
6826 RAM (for small model) or external RAM (for large model).
6827 This in fact makes them
6830 \begin_inset LatexCommand \index{static}
6836 so by default functions are non-reentrant
6837 \begin_inset LatexCommand \index{reentrant}
6845 They can be placed on the stack
6846 \begin_inset LatexCommand \index{stack}
6863 \begin_inset LatexCommand \index{-\/-stack-auto}
6869 option or by using the
6872 \begin_inset LatexCommand \index{reentrant}
6878 keyword in the function declaration, e.g.:
6887 unsigned char foo(char i) reentrant
6900 Since stack space on 8051 is limited, the
6918 option should be used sparingly.
6919 Note that the reentrant keyword just means that the parameters & local
6920 variables will be allocated to the stack, it
6924 mean that the function is register bank independent.
6928 Local variables can be assigned storage classes and absolute
6929 \begin_inset LatexCommand \index{Absolute addressing}
6939 unsigned char foo() {
6945 xdata unsigned char i;
6957 data at 0x31 unsiged char j;
6972 In the above example the variable
6976 will be allocated in the external ram,
6980 in bit addressable space and
6999 or when a function is declared as
7003 this should only be done for static variables.
7006 Parameters however are not allowed any storage class, (storage classes for
7007 parameters will be ignored), their allocation is governed by the memory
7008 model in use, and the reentrancy options.
7012 \begin_inset LatexCommand \index{Overlaying}
7020 \begin_inset LatexCommand \index{reentrant}
7024 functions SDCC will try to reduce internal ram space usage by overlaying
7025 parameters and local variables of a function (if possible).
7026 Parameters and local variables of a function will be allocated to an overlayabl
7027 e segment if the function has
7029 no other function calls and the function is non-reentrant and the memory
7031 \begin_inset LatexCommand \index{Memory model}
7038 If an explicit storage class
7039 \begin_inset LatexCommand \index{Storage class}
7043 is specified for a local variable, it will NOT be overlayed.
7046 Note that the compiler (not the linkage editor) makes the decision for overlayin
7048 Functions that are called from an interrupt service routine should be preceded
7049 by a #pragma\SpecialChar ~
7051 \begin_inset LatexCommand \index{\#pragma NOOVERLAY}
7055 if they are not reentrant.
7058 Also note that the compiler does not do any processing of inline
7059 \begin_inset LatexCommand \index{inline}
7063 assembler code, so the compiler might incorrectly assign local variables
7064 and parameters of a function into the overlay segment if the inline assembler
7065 code calls other c-functions that might use the overlay.
7066 In that case the #pragma\SpecialChar ~
7067 NOOVERLAY should be used.
7070 Parameters and Local variables of functions that contain 16 or 32 bit multiplica
7072 \begin_inset LatexCommand \index{Multiplication}
7077 \begin_inset LatexCommand \index{Division}
7081 will NOT be overlayed since these are implemented using external functions,
7091 \begin_inset LatexCommand \index{\#pragma NOOVERLAY}
7097 void set_error(unsigned char errcd)
7113 void some_isr () interrupt
7114 \begin_inset LatexCommand \index{interrupt}
7119 \begin_inset LatexCommand \index{using}
7152 In the above example the parameter
7160 would be assigned to the overlayable segment if the #pragma\SpecialChar ~
7162 not present, this could cause unpredictable runtime behavior when called
7164 The #pragma\SpecialChar ~
7165 NOOVERLAY ensures that the parameters and local variables for
7166 the function are NOT overlayed.
7169 Interrupt Service Routines
7172 SDCC allows interrupt service routines to be coded in C, with some extended
7179 void timer_isr (void) interrupt 2 using 1
7192 The number following the
7195 \begin_inset LatexCommand \index{interrupt}
7201 keyword is the interrupt number this routine will service.
7202 The compiler will insert a call to this routine in the interrupt vector
7203 table for the interrupt number specified.
7208 keyword is used to tell the compiler to use the specified register bank
7209 (8051 specific) when generating code for this function.
7210 Note that when some function is called from an interrupt service routine
7211 it should be preceded by a #pragma\SpecialChar ~
7213 \begin_inset LatexCommand \index{\#pragma NOOVERLAY}
7217 if it is not reentrant.
7218 A special note here, int (16 bit) and long (32 bit) integer division
7219 \begin_inset LatexCommand \index{Division}
7224 \begin_inset LatexCommand \index{Multiplication}
7229 \begin_inset LatexCommand \index{Modulus}
7233 operations are implemented using external support routines developed in
7234 ANSI-C, if an interrupt service routine needs to do any of these operations
7235 then the support routines (as mentioned in a following section) will have
7236 to be recompiled using the
7249 \begin_inset LatexCommand \index{-\/-stack-auto}
7255 option and the source file will need to be compiled using the
7270 \begin_inset LatexCommand \index{-\/-int-long-rent}
7277 If you have multiple source files in your project, interrupt service routines
7278 can be present in any of them, but a prototype of the isr MUST be present
7279 or included in the file that contains the function
7286 Interrupt Numbers and the corresponding address & descriptions for the Standard
7287 8051 are listed below.
7288 SDCC will automatically adjust the interrupt vector table to the maximum
7289 interrupt number specified.
7295 \begin_inset Tabular
7296 <lyxtabular version="3" rows="6" columns="3">
7298 <column alignment="block" valignment="top" leftline="true" width="0in">
7299 <column alignment="block" valignment="top" leftline="true" width="0in">
7300 <column alignment="block" valignment="top" leftline="true" rightline="true" width="0in">
7301 <row topline="true" bottomline="true">
7302 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
7310 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
7318 <cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
7327 <row topline="true">
7328 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
7336 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
7344 <cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
7353 <row topline="true">
7354 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
7362 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
7370 <cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
7379 <row topline="true">
7380 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
7388 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
7396 <cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
7405 <row topline="true">
7406 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
7414 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
7422 <cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
7431 <row topline="true" bottomline="true">
7432 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
7440 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
7448 <cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
7465 If the interrupt service routine is defined without
7468 \begin_inset LatexCommand \index{using}
7474 a register bank or with register bank 0 (using 0), the compiler will save
7475 the registers used by itself on the stack upon entry and restore them at
7476 exit, however if such an interrupt service routine calls another function
7477 then the entire register bank will be saved on the stack.
7478 This scheme may be advantageous for small interrupt service routines which
7479 have low register usage.
7482 If the interrupt service routine is defined to be using a specific register
7487 are save and restored, if such an interrupt service routine calls another
7488 function (using another register bank) then the entire register bank of
7489 the called function will be saved on the stack.
7490 This scheme is recommended for larger interrupt service routines.
7493 Calling other functions from an interrupt service routine is not recommended,
7494 avoid it if possible.
7498 Also see the _naked modifier.
7506 <TODO: this isn't implemented at all!>
7512 A special keyword may be associated with a function declaring it as
7517 SDCC will generate code to disable all interrupts upon entry to a critical
7518 function and enable them back before returning.
7519 Note that nesting critical functions may cause unpredictable results.
7544 The critical attribute maybe used with other attributes like
7550 \begin_inset LatexCommand \index{Naked functions}
7557 A special keyword may be associated with a function declaring it as
7560 \begin_inset LatexCommand \index{\_naked}
7571 function modifier attribute prevents the compiler from generating prologue
7572 \begin_inset LatexCommand \index{function prologue}
7577 \begin_inset LatexCommand \index{function epilogue}
7581 code for that function.
7582 This means that the user is entirely responsible for such things as saving
7583 any registers that may need to be preserved, selecting the proper register
7584 bank, generating the
7588 instruction at the end, etc.
7589 Practically, this means that the contents of the function must be written
7590 in inline assembler.
7591 This is particularly useful for interrupt functions, which can have a large
7592 (and often unnecessary) prologue/epilogue.
7593 For example, compare the code generated by these two functions:
7599 data unsigned char counter;
7601 void simpleInterrupt(void) interrupt
7602 \begin_inset LatexCommand \index{interrupt}
7620 void nakedInterrupt(void) interrupt 2 _naked
7629 \begin_inset LatexCommand \index{\_asm}
7658 ; MUST explicitly include ret in _naked function.
7665 \begin_inset LatexCommand \index{\_endasm}
7677 For an 8051 target, the generated simpleInterrupt looks like:
7822 whereas nakedInterrupt looks like:
7847 ; MUST explicitly include ret(i) in _naked function.
7853 While there is nothing preventing you from writing C code inside a _naked
7854 function, there are many ways to shoot yourself in the foot doing this,
7855 and it is recommended that you stick to inline assembler.
7858 Functions using private banks
7859 \begin_inset LatexCommand \index{bank}
7869 \begin_inset LatexCommand \index{using}
7875 attribute (which tells the compiler to use a register bank other than the
7876 default bank zero) should only be applied to
7879 \begin_inset LatexCommand \index{interrupt}
7885 functions (see note 1 below).
7886 This will in most circumstances make the generated ISR code more efficient
7887 since it will not have to save registers on the stack.
7894 attribute will have no effect on the generated code for a
7898 function (but may occasionally be useful anyway
7904 possible exception: if a function is called ONLY from 'interrupt' functions
7905 using a particular bank, it can be declared with the same 'using' attribute
7906 as the calling 'interrupt' functions.
7907 For instance, if you have several ISRs using bank one, and all of them
7908 call memcpy(), it might make sense to create a specialized version of memcpy()
7909 'using 1', since this would prevent the ISR from having to save bank zero
7910 to the stack on entry and switch to bank zero before calling the function
7917 (pending: I don't think this has been done yet)
7924 function using a non-zero bank will assume that it can trash that register
7925 bank, and will not save it.
7926 Since high-priority interrupts
7927 \begin_inset LatexCommand \index{interrupt priority}
7931 can interrupt low-priority ones on the 8051 and friends, this means that
7932 if a high-priority ISR
7936 a particular bank occurs while processing a low-priority ISR
7940 the same bank, terrible and bad things can happen.
7941 To prevent this, no single register bank should be
7945 by both a high priority and a low priority ISR.
7946 This is probably most easily done by having all high priority ISRs use
7947 one bank and all low priority ISRs use another.
7948 If you have an ISR which can change priority at runtime, you're on your
7949 own: I suggest using the default bank zero and taking the small performance
7953 It is most efficient if your ISR calls no other functions.
7954 If your ISR must call other functions, it is most efficient if those functions
7955 use the same bank as the ISR (see note 1 below); the next best is if the
7956 called functions use bank zero.
7957 It is very inefficient to call a function using a different, non-zero bank
7963 \begin_inset LatexCommand \index{Absolute addressing}
7970 Data items can be assigned an absolute address with the
7973 \begin_inset LatexCommand \index{at}
7979 keyword, in addition to a storage class, e.g.:
7986 \begin_inset LatexCommand \index{xdata}
7991 \begin_inset LatexCommand \index{at}
7995 0x8000 unsigned char PORTA_8255 ;
8001 In the above example the PORTA_8255 will be allocated to the location 0x8000
8002 of the external ram.
8003 Note that this feature is provided to give the programmer access to
8007 devices attached to the controller.
8008 The compiler does not actually reserve any space for variables declared
8009 in this way (they are implemented with an equate in the assembler).
8010 Thus it is left to the programmer to make sure there are no overlaps with
8011 other variables that are declared without the absolute address.
8012 The assembler listing file (.lst
8013 \begin_inset LatexCommand \index{.lst}
8017 ) and the linker output files (.rst
8018 \begin_inset LatexCommand \index{.rst}
8023 \begin_inset LatexCommand \index{.map}
8027 ) are a good places to look for such overlaps.
8031 Absolute address can be specified for variables in all storage classes,
8039 \begin_inset LatexCommand \index{bit}
8044 \begin_inset LatexCommand \index{at}
8054 The above example will allocate the variable at offset 0x02 in the bit-addressab
8056 There is no real advantage to assigning absolute addresses to variables
8057 in this manner, unless you want strict control over all the variables allocated.
8061 \begin_inset LatexCommand \index{Startup code}
8068 The compiler inserts a call to the C routine
8070 _sdcc_external_startup()
8071 \begin_inset LatexCommand \index{\_sdcc\_external\_startup()}
8080 at the start of the CODE area.
8081 This routine is in the runtime library
8082 \begin_inset LatexCommand \index{Runtime library}
8087 By default this routine returns 0, if this routine returns a non-zero value,
8088 the static & global variable initialization will be skipped and the function
8089 main will be invoked Other wise static & global variables will be initialized
8090 before the function main is invoked.
8093 _sdcc_external_startup()
8095 routine to your program to override the default if you need to setup hardware
8096 or perform some other critical operation prior to static & global variable
8100 Inline Assembler Code
8101 \begin_inset LatexCommand \index{Assembler routines}
8108 SDCC allows the use of in-line assembler with a few restriction as regards
8110 All labels defined within inline assembler code
8118 where nnnn is a number less than 100 (which implies a limit of utmost 100
8119 inline assembler labels
8127 It is strongly recommended that each assembly instruction (including labels)
8128 be placed in a separate line (as the example shows).
8142 \begin_inset LatexCommand \index{-\/-peep-asm}
8148 command line option is used, the inline assembler code will be passed through
8149 the peephole optimizer
8150 \begin_inset LatexCommand \index{Peephole optimizer}
8155 This might cause some unexpected changes in the inline assembler code.
8156 Please go throught the peephole optimizer rules defined in file
8160 carefully before using this option.
8167 \begin_inset LatexCommand \index{\_asm}
8197 \begin_inset LatexCommand \index{\_endasm}
8210 The inline assembler code can contain any valid code understood by the assembler
8211 , this includes any assembler directives and comment lines.
8212 The compiler does not do any validation of the code within the
8222 Inline assembler code cannot reference any C-Labels, however it can reference
8224 \begin_inset LatexCommand \index{Labels}
8228 defined by the inline assembler, e.g.:
8254 ; some assembler code
8274 /* some more c code */
8276 clabel:\SpecialChar ~
8278 /* inline assembler cannot reference this label */
8290 $0003: ;label (can be reference by inline assembler only)
8302 /* some more c code */
8310 In other words inline assembly code can access labels defined in inline
8311 assembly within the scope of the funtion.
8315 The same goes the other way, ie.
8316 labels defines in inline assembly CANNOT be accessed by C statements.
8320 \begin_inset LatexCommand \index{int (16 bit)}
8325 \begin_inset LatexCommand \index{long (32 bit)}
8332 For signed & unsigned int (16 bit) and long (32 bit) variables, division,
8333 multiplication and modulus operations are implemented by support routines.
8334 These support routines are all developed in ANSI-C to facilitate porting
8335 to other MCUs, although some model specific assembler optimations are used.
8336 The following files contain the described routine, all of them can be found
8337 in <installdir>/share/sdcc/lib.
8343 <pending: tabularise this>
8349 _mulint.c - 16 bit multiplication
8351 _divsint.c - signed 16 bit division (calls _divuint)
8353 _divuint.c - unsigned 16 bit division
8355 _modsint.c - signed 16 bit modulus (call _moduint)
8357 _moduint.c - unsigned 16 bit modulus
8359 _mullong.c - 32 bit multiplication
8361 _divslong.c - signed 32 division (calls _divulong)
8363 _divulong.c - unsigned 32 division
8365 _modslong.c - signed 32 bit modulus (calls _modulong)
8367 _modulong.c - unsigned 32 bit modulus
8375 Since they are compiled as
8380 \begin_inset LatexCommand \index{reentrant}
8385 \begin_inset LatexCommand \index{interrupt}
8389 service routines should not do any of the above operations.
8390 If this is unavoidable then the above routines will need to be compiled
8404 \begin_inset LatexCommand \index{-\/-stack-auto}
8410 option, after which the source program will have to be compiled with
8423 \begin_inset LatexCommand \index{-\/-int-long-rent}
8432 Floating Point Support
8433 \begin_inset LatexCommand \index{Floating point support}
8440 SDCC supports IEEE (single precision 4bytes) floating point numbers.The floating
8441 point support routines are derived from gcc's floatlib.c and consists of
8442 the following routines:
8448 <pending: tabularise this>
8454 _fsadd.c - add floating point numbers
8456 _fssub.c - subtract floating point numbers
8458 _fsdiv.c - divide floating point numbers
8460 _fsmul.c - multiply floating point numbers
8462 _fs2uchar.c - convert floating point to unsigned char
8464 _fs2char.c - convert floating point to signed char
8466 _fs2uint.c - convert floating point to unsigned int
8468 _fs2int.c - convert floating point to signed int
8470 _fs2ulong.c - convert floating point to unsigned long
8472 _fs2long.c - convert floating point to signed long
8474 _uchar2fs.c - convert unsigned char to floating point
8476 _char2fs.c - convert char to floating point number
8478 _uint2fs.c - convert unsigned int to floating point
8480 _int2fs.c - convert int to floating point numbers
8482 _ulong2fs.c - convert unsigned long to floating point number
8484 _long2fs.c - convert long to floating point number
8492 Note if all these routines are used simultaneously the data space might
8494 For serious floating point usage it is strongly recommended that the large
8499 \begin_inset LatexCommand \index{Memory model}
8504 \begin_inset LatexCommand \index{MCS51 memory}
8511 SDCC allows two memory models for MCS51 code, small and large.
8512 Modules compiled with different memory models should
8516 be combined together or the results would be unpredictable.
8517 The library routines supplied with the compiler are compiled as both small
8519 The compiled library modules are contained in seperate directories as small
8520 and large so that you can link to either set.
8524 When the large model is used all variables declared without a storage class
8525 will be allocated into the external ram, this includes all parameters and
8526 local variables (for non-reentrant
8527 \begin_inset LatexCommand \index{reentrant}
8532 When the small model is used variables without storage class are allocated
8533 in the internal ram.
8536 Judicious usage of the processor specific storage classes
8537 \begin_inset LatexCommand \index{Storage class}
8541 and the 'reentrant' function type will yield much more efficient code,
8542 than using the large model.
8543 Several optimizations are disabled when the program is compiled using the
8544 large model, it is therefore strongly recommdended that the small model
8545 be used unless absolutely required.
8549 \begin_inset LatexCommand \index{Memory model}
8554 \begin_inset LatexCommand \index{DS390 memory model}
8561 The only model supported is Flat 24
8562 \begin_inset LatexCommand \index{Flat 24 (memory model)}
8567 This generates code for the 24 bit contiguous addressing mode of the Dallas
8569 In this mode, up to four meg of external RAM or code space can be directly
8571 See the data sheets at www.dalsemi.com for further information on this part.
8575 In older versions of the compiler, this option was used with the MCS51 code
8581 Now, however, the '390 has it's own code generator, selected by the
8590 Note that the compiler does not generate any code to place the processor
8591 into 24 bitmode (although
8595 in the ds390 libraries will do that for you).
8601 \begin_inset LatexCommand \index{Tinibios (DS390)}
8605 , the boot loader or similar code must ensure that the processor is in 24
8606 bit contiguous addressing mode before calling the SDCC startup code.
8624 option, variables will by default be placed into the XDATA segment.
8629 Segments may be placed anywhere in the 4 meg address space using the usual
8641 Note that if any segments are located above 64K, the -r flag must be passed
8642 to the linker to generate the proper segment relocations, and the Intel
8643 HEX output format must be used.
8644 The -r flag can be passed to the linker by using the option
8648 on the sdcc command line.
8649 However, currently the linker can not handle code segments > 64k.
8652 Defines Created by the Compiler
8653 \begin_inset LatexCommand \index{Defines created by the compiler}
8660 The compiler creates the following #defines
8661 \begin_inset LatexCommand \index{\#defines}
8669 \begin_inset LatexCommand \index{SDCC}
8673 - this Symbol is always defined.
8677 \begin_inset LatexCommand \index{SDCC\_mcs51}
8682 \begin_inset LatexCommand \index{SDCC\_ds390}
8687 \begin_inset LatexCommand \index{SDCC\_z80}
8691 , etc - depending on the model used (e.g.: -mds390)
8695 \begin_inset LatexCommand \index{\_\_mcs51}
8700 \begin_inset LatexCommand \index{\_\_ds390}
8705 \begin_inset LatexCommand \index{\_\_z80}
8709 , etc - depending on the model used (e.g.
8714 \begin_inset LatexCommand \index{SDCC\_STACK\_AUTO}
8718 - this symbol is defined when
8736 \begin_inset LatexCommand \index{SDCC\_MODEL\_SMALL}
8758 \begin_inset LatexCommand \index{SDCC\_MODEL\_LARGE}
8780 \begin_inset LatexCommand \index{SDCC\_USE\_XSTACK}
8802 \begin_inset LatexCommand \index{SDCC\_STACK\_TENBIT}
8814 \begin_inset LatexCommand \index{SDCC\_MODEL\_FLAT24}
8829 \begin_inset LatexCommand \index{Optimizations}
8836 SDCC performs a host of standard optimizations in addition to some MCU specific
8839 \layout Subsubsection
8841 Sub-expression Elimination
8842 \begin_inset LatexCommand \index{Subexpression elimination}
8849 The compiler does local and global common subexpression elimination, e.g.:
8864 will be translated to
8880 Some subexpressions are not as obvious as the above example, e.g.:
8894 In this case the address arithmetic a->b[i] will be computed only once;
8895 the equivalent code in C would be.
8911 The compiler will try to keep these temporary variables in registers.
8912 \layout Subsubsection
8914 Dead-Code Elimination
8915 \begin_inset LatexCommand \index{Dead-code elimination}
8934 i = 1; \SpecialChar ~
8939 global = 1;\SpecialChar ~
8952 global = 3;\SpecialChar ~
8967 int global; void f ()
8980 \layout Subsubsection
8983 \begin_inset LatexCommand \index{Copy propagation}
9046 Note: the dead stores created by this copy propagation will be eliminated
9047 by dead-code elimination.
9048 \layout Subsubsection
9051 \begin_inset LatexCommand \index{Loop optimization}
9058 Two types of loop optimizations are done by SDCC loop invariant lifting
9059 and strength reduction of loop induction variables.
9060 In addition to the strength reduction the optimizer marks the induction
9061 variables and the register allocator tries to keep the induction variables
9062 in registers for the duration of the loop.
9063 Because of this preference of the register allocator
9064 \begin_inset LatexCommand \index{Register allocation}
9068 , loop induction optimization causes an increase in register pressure, which
9069 may cause unwanted spilling of other temporary variables into the stack
9070 \begin_inset LatexCommand \index{stack}
9075 The compiler will generate a warning message when it is forced to allocate
9076 extra space either on the stack or data space.
9077 If this extra space allocation is undesirable then induction optimization
9078 can be eliminated either for the entire source file (with -
9088 -noinduction option) or for a given function only using #pragma\SpecialChar ~
9090 \begin_inset LatexCommand \index{\#pragma NOINDUCTION}
9104 for (i = 0 ; i < 100 ; i ++)
9122 for (i = 0; i < 100; i++)
9132 As mentioned previously some loop invariants are not as apparent, all static
9133 address computations are also moved out of the loop.
9138 \begin_inset LatexCommand \index{Strength reduction}
9142 , this optimization substitutes an expression by a cheaper expression:
9148 for (i=0;i < 100; i++)
9168 for (i=0;i< 100;i++) {
9172 ar[itemp1] = itemp2;
9188 The more expensive multiplication
9189 \begin_inset LatexCommand \index{Multiplication}
9193 is changed to a less expensive addition.
9194 \layout Subsubsection
9197 \begin_inset LatexCommand \index{Loop reversing}
9204 This optimization is done to reduce the overhead of checking loop boundaries
9205 for every iteration.
9206 Some simple loops can be reversed and implemented using a
9207 \begin_inset Quotes eld
9210 decrement and jump if not zero
9211 \begin_inset Quotes erd
9215 SDCC checks for the following criterion to determine if a loop is reversible
9216 (note: more sophisticated compilers use data-dependency analysis to make
9217 this determination, SDCC uses a more simple minded analysis).
9220 The 'for' loop is of the form
9226 for (<symbol> = <expression> ; <sym> [< | <=] <expression> ; [<sym>++ |
9236 The <for body> does not contain
9237 \begin_inset Quotes eld
9241 \begin_inset Quotes erd
9245 \begin_inset Quotes erd
9251 All goto's are contained within the loop.
9254 No function calls within the loop.
9257 The loop control variable <sym> is not assigned any value within the loop
9260 The loop control variable does NOT participate in any arithmetic operation
9264 There are NO switch statements in the loop.
9265 \layout Subsubsection
9267 Algebraic Simplifications
9270 SDCC does numerous algebraic simplifications, the following is a small sub-set
9271 of these optimizations.
9277 i = j + 0 ; /* changed to */ i = j;
9279 i /= 2; /* changed to */ i >>= 1;
9281 i = j - j ; /* changed to */ i = 0;
9283 i = j / 1 ; /* changed to */ i = j;
9289 Note the subexpressions
9290 \begin_inset LatexCommand \index{Subexpression}
9294 given above are generally introduced by macro expansions or as a result
9295 of copy/constant propagation.
9296 \layout Subsubsection
9299 \begin_inset LatexCommand \index{switch statement}
9306 SDCC changes switch statements to jump tables
9307 \begin_inset LatexCommand \index{jump tables}
9311 when the following conditions are true.
9315 The case labels are in numerical sequence, the labels need not be in order,
9316 and the starting number need not be one or zero.
9322 switch(i) {\SpecialChar ~
9429 Both the above switch statements will be implemented using a jump-table.
9432 The number of case labels is at least three, since it takes two conditional
9433 statements to handle the boundary conditions.
9436 The number of case labels is less than 84, since each label takes 3 bytes
9437 and a jump-table can be utmost 256 bytes long.
9441 Switch statements which have gaps in the numeric sequence or those that
9442 have more that 84 case labels can be split into more than one switch statement
9443 for efficient code generation, e.g.:
9481 If the above switch statement is broken down into two switch statements
9515 case 9: \SpecialChar ~
9525 case 12:\SpecialChar ~
9535 then both the switch statements will be implemented using jump-tables whereas
9536 the unmodified switch statement will not be.
9537 \layout Subsubsection
9539 Bit-shifting Operations
9540 \begin_inset LatexCommand \index{Bit shifting}
9547 Bit shifting is one of the most frequently used operation in embedded programmin
9549 SDCC tries to implement bit-shift operations in the most efficient way
9569 generates the following code:
9587 In general SDCC will never setup a loop if the shift count is known.
9627 Note that SDCC stores numbers in little-endian format (i.e.
9628 lowest order first).
9629 \layout Subsubsection
9632 \begin_inset LatexCommand \index{Bit rotation}
9639 A special case of the bit-shift operation is bit rotation, SDCC recognizes
9640 the following expression to be a left bit-rotation:
9651 i = ((i << 1) | (i >> 7));
9659 will generate the following code:
9675 SDCC uses pattern matching on the parse tree to determine this operation.Variatio
9676 ns of this case will also be recognized as bit-rotation, i.e.:
9682 i = ((i >> 7) | (i << 1)); /* left-bit rotation */
9683 \layout Subsubsection
9686 \begin_inset LatexCommand \index{Highest Order Bit}
9693 It is frequently required to obtain the highest order bit of an integral
9694 type (long, int, short or char types).
9695 SDCC recognizes the following expression to yield the highest order bit
9696 and generates optimized code for it, e.g.:
9717 hob = (gint >> 15) & 1;
9730 will generate the following code:
9769 000A E5*01\SpecialChar ~
9797 000C 33\SpecialChar ~
9828 000D E4\SpecialChar ~
9859 000E 13\SpecialChar ~
9890 000F F5*02\SpecialChar ~
9920 Variations of this case however will
9925 It is a standard C expression, so I heartily recommend this be the only
9926 way to get the highest order bit, (it is portable).
9927 Of course it will be recognized even if it is embedded in other expressions,
9934 xyz = gint + ((gint >> 15) & 1);
9940 will still be recognized.
9941 \layout Subsubsection
9944 \begin_inset LatexCommand \index{Peephole optimizer}
9951 The compiler uses a rule based, pattern matching and re-writing mechanism
9952 for peep-hole optimization.
9957 a peep-hole optimizer by Christopher W.
9958 Fraser (cwfraser@microsoft.com).
9959 A default set of rules are compiled into the compiler, additional rules
9960 may be added with the
9973 \begin_inset LatexCommand \index{-\/-peep-file}
9980 The rule language is best illustrated with examples.
10008 The above rule will change the following assembly
10009 \begin_inset LatexCommand \index{Assembler routines}
10043 Note: All occurrences of a
10047 (pattern variable) must denote the same string.
10048 With the above rule, the assembly sequence:
10066 will remain unmodified.
10070 Other special case optimizations may be added by the user (via
10086 some variants of the 8051 MCU allow only
10095 The following two rules will change all
10117 replace { lcall %1 } by { acall %1 }
10119 replace { ljmp %1 } by { ajmp %1 }
10127 inline-assembler code
10129 is also passed through the peep hole optimizer, thus the peephole optimizer
10130 can also be used as an assembly level macro expander.
10131 The rules themselves are MCU dependent whereas the rule language infra-structur
10132 e is MCU independent.
10133 Peephole optimization rules for other MCU can be easily programmed using
10138 The syntax for a rule is as follows:
10144 rule := replace [ restart ] '{' <assembly sequence> '
10182 <assembly sequence> '
10200 '}' [if <functionName> ] '
10208 <assembly sequence> := assembly instruction (each instruction including
10209 labels must be on a separate line).
10213 The optimizer will apply to the rules one by one from the top in the sequence
10214 of their appearance, it will terminate when all rules are exhausted.
10215 If the 'restart' option is specified, then the optimizer will start matching
10216 the rules again from the top, this option for a rule is expensive (performance)
10217 , it is intended to be used in situations where a transformation will trigger
10218 the same rule again.
10219 An example of this (not a good one, it has side effects) is the following
10246 Note that the replace pattern cannot be a blank, but can be a comment line.
10247 Without the 'restart' option only the inner most 'pop' 'push' pair would
10248 be eliminated, i.e.:
10300 the restart option the rule will be applied again to the resulting code
10301 and then all the pop-push pairs will be eliminated to yield:
10319 A conditional function can be attached to a rule.
10320 Attaching rules are somewhat more involved, let me illustrate this with
10351 The optimizer does a look-up of a function name table defined in function
10356 in the source file SDCCpeeph.c, with the name
10361 If it finds a corresponding entry the function is called.
10362 Note there can be no parameters specified for these functions, in this
10367 is crucial, since the function
10371 expects to find the label in that particular variable (the hash table containin
10372 g the variable bindings is passed as a parameter).
10373 If you want to code more such functions, take a close look at the function
10374 labelInRange and the calling mechanism in source file SDCCpeeph.c.
10375 I know this whole thing is a little kludgey, but maybe some day we will
10376 have some better means.
10377 If you are looking at this file, you will also see the default rules that
10378 are compiled into the compiler, you can add your own rules in the default
10379 set there if you get tired of specifying the -
10393 \begin_inset LatexCommand \index{Pragmas}
10400 SDCC supports the following #pragma directives.
10404 \begin_inset LatexCommand \index{\#pragma SAVE}
10408 - this will save all current options to the SAVE/RESTORE stack.
10413 \begin_inset LatexCommand \index{\#pragma RESTORE}
10417 - will restore saved options from the last save.
10418 SAVEs & RESTOREs can be nested.
10419 SDCC uses a SAVE/RESTORE stack: SAVE pushes current options to the stack,
10420 RESTORE pulls current options from the stack.
10425 \begin_inset LatexCommand \index{\#pragma NOGCSE}
10429 - will stop global subexpression elimination.
10433 \begin_inset LatexCommand \index{\#pragma NOINDUCTION}
10437 - will stop loop induction optimizations.
10441 \begin_inset LatexCommand \index{\#pragma NOJTBOUND}
10445 - will not generate code for boundary value checking, when switch statements
10446 are turned into jump-tables.
10450 \begin_inset LatexCommand \index{\#pragma NOOVERLAY}
10454 - the compiler will not overlay the parameters and local variables of a
10459 \begin_inset LatexCommand \index{\#pragma LESS\_PEDANTIC}
10463 - the compiler will not warn you anymore for obvious mistakes, you'r on
10468 \begin_inset LatexCommand \index{\#pragma NOLOOPREVERSE}
10472 - Will not do loop reversal optimization
10476 \begin_inset LatexCommand \index{\#pragma EXCLUDE}
10480 NONE | {acc[,b[,dpl[,dph]]] - The exclude pragma disables generation of
10482 \begin_inset LatexCommand \index{push/pop}
10486 instruction in ISR function (using interrupt
10487 \begin_inset LatexCommand \index{interrupt}
10492 The directive should be placed immediately before the ISR function definition
10493 and it affects ALL ISR functions following it.
10494 To enable the normal register saving for ISR functions use #pragma\SpecialChar ~
10495 EXCLUDE\SpecialChar ~
10497 \begin_inset LatexCommand \index{\#pragma EXCLUDE}
10505 \begin_inset LatexCommand \index{\#pragma NOIV}
10509 - Do not generate interrupt vector table entries for all ISR functions
10510 defined after the pragma.
10511 This is useful in cases where the interrupt vector table must be defined
10512 manually, or when there is a secondary, manually defined interrupt vector
10514 for the autovector feature of the Cypress EZ-USB FX2).
10518 \begin_inset LatexCommand \index{\#pragma CALLEE-SAVES}
10523 \begin_inset LatexCommand \index{function prologue}
10527 function1[,function2[,function3...]] - The compiler by default uses a caller
10528 saves convention for register saving across function calls, however this
10529 can cause unneccessary register pushing & popping when calling small functions
10530 from larger functions.
10531 This option can be used to switch off the register saving convention for
10532 the function names specified.
10533 The compiler will not save registers when calling these functions, extra
10534 code need to be manually inserted at the entry & exit for these functions
10535 to save & restore the registers used by these functions, this can SUBSTANTIALLY
10536 reduce code & improve run time performance of the generated code.
10537 In the future the compiler (with interprocedural analysis) may be able
10538 to determine the appropriate scheme to use for each function call.
10549 -callee-saves command line option is used, the function names specified
10550 in #pragma\SpecialChar ~
10552 \begin_inset LatexCommand \index{\#pragma CALLEE-SAVES}
10556 is appended to the list of functions specified in the command line.
10559 The pragma's are intended to be used to turn-off certain optimizations which
10560 might cause the compiler to generate extra stack / data space to store
10561 compiler generated temporary variables.
10562 This usually happens in large functions.
10563 Pragma directives should be used as shown in the following example, they
10564 are used to control options & optimizations for a given function; pragmas
10565 should be placed before and/or after a function, placing pragma's inside
10566 a function body could have unpredictable results.
10573 \begin_inset LatexCommand \index{\#pragma SAVE}
10577 /* save the current settings */
10580 \begin_inset LatexCommand \index{\#pragma NOGCSE}
10584 /* turnoff global subexpression elimination */
10586 #pragma NOINDUCTION
10587 \begin_inset LatexCommand \index{\#pragma NOINDUCTION}
10591 /* turn off induction optimizations */
10614 \begin_inset LatexCommand \index{\#pragma RESTORE}
10618 /* turn the optimizations back on */
10624 The compiler will generate a warning message when extra space is allocated.
10625 It is strongly recommended that the SAVE and RESTORE pragma's be used when
10626 changing options for a function.
10631 <pending: this is messy and incomplete>
10636 Compiler support routines (_gptrget, _mulint etc)
10639 Stdclib functions (puts, printf, strcat etc)
10642 Math functions (sin, pow, sqrt etc)
10645 license statements for the libraries are missing
10648 Interfacing with Assembly Routines
10649 \begin_inset LatexCommand \index{Assembler routines}
10654 \layout Subsubsection
10656 Global Registers used for Parameter Passing
10657 \begin_inset LatexCommand \index{Parameter passing}
10664 The compiler always uses the global registers
10667 \begin_inset LatexCommand \index{DPTR, DPH, DPL}
10672 \begin_inset LatexCommand \index{B (register)}
10681 \begin_inset LatexCommand \index{ACC}
10687 to pass the first parameter to a routine.
10688 The second parameter onwards is either allocated on the stack (for reentrant
10699 -stack-auto is used) or in the internal / external ram (depending on the
10702 \layout Subsubsection
10704 Assembler Routine(non-reentrant
10705 \begin_inset LatexCommand \index{reentrant}
10710 \begin_inset LatexCommand \index{Assembler routines (non-reentrant)}
10717 In the following example the function cfunc calls an assembler routine asm_func,
10718 which takes two parameters.
10724 extern int asm_func(unsigned char, unsigned char);
10728 int c_func (unsigned char i, unsigned char j)
10736 return asm_func(i,j);
10750 return c_func(10,9);
10758 The corresponding assembler function is:
10764 .globl _asm_func_PARM_2
10828 add a,_asm_func_PARM_2
10849 \begin_inset LatexCommand \index{DPTR, DPH, DPL}
10869 Note here that the return values are placed in 'dpl' - One byte return value,
10870 'dpl' LSB & 'dph' MSB for two byte values.
10871 'dpl', 'dph' and 'b' for three byte values (generic pointers) and 'dpl','dph','
10872 b' & 'acc' for four byte values.
10875 The parameter naming convention is _<function_name>_PARM_<n>, where n is
10876 the parameter number starting from 1, and counting from the left.
10877 The first parameter is passed in
10878 \begin_inset Quotes eld
10882 \begin_inset Quotes erd
10885 for One bye parameter,
10886 \begin_inset Quotes eld
10890 \begin_inset Quotes erd
10894 \begin_inset Quotes eld
10898 \begin_inset Quotes erd
10901 for three bytes and
10902 \begin_inset Quotes eld
10906 \begin_inset Quotes erd
10909 for four bytes, the varible name for the second parameter will be _<function_na
10914 Assemble the assembler routine with the following command:
10921 asx8051 -losg asmfunc.asm
10928 Then compile and link the assembler routine to the C source file with the
10936 sdcc cfunc.c asmfunc.rel
10937 \layout Subsubsection
10939 Assembler Routine(reentrant
10940 \begin_inset LatexCommand \index{reentrant}
10945 \begin_inset LatexCommand \index{Assembler routines (reentrant)}
10952 In this case the second parameter onwards will be passed on the stack, the
10953 parameters are pushed from right to left i.e.
10954 after the call the left most parameter will be on the top of the stack.
10955 Here is an example:
10961 extern int asm_func(unsigned char, unsigned char);
10965 int c_func (unsigned char i, unsigned char j) reentrant
10973 return asm_func(i,j);
10987 return c_func(10,9);
10995 The corresponding assembler routine is:
11105 The compiling and linking procedure remains the same, however note the extra
11106 entry & exit linkage required for the assembler code, _bp is the stack
11107 frame pointer and is used to compute the offset into the stack for parameters
11108 and local variables.
11112 \begin_inset LatexCommand \index{stack}
11117 \begin_inset LatexCommand \index{External stack}
11124 The external stack is located at the start of the external ram segment,
11125 and is 256 bytes in size.
11136 -xstack option is used to compile the program, the parameters and local
11137 variables of all reentrant functions are allocated in this area.
11138 This option is provided for programs with large stack space requirements.
11139 When used with the -
11149 -stack-auto option, all parameters and local variables are allocated on
11150 the external stack (note support libraries will need to be recompiled with
11154 The compiler outputs the higher order address byte of the external ram segment
11155 into PORT P2, therefore when using the External Stack option, this port
11156 MAY NOT be used by the application program.
11160 \begin_inset LatexCommand \index{ANSI-compliance}
11167 Deviations from the compliancy.
11170 functions are not always reentrant.
11173 structures cannot be assigned values directly, cannot be passed as function
11174 parameters or assigned to each other and cannot be a return value from
11201 s1 = s2 ; /* is invalid in SDCC although allowed in ANSI */
11212 struct s foo1 (struct s parms) /* is invalid in SDCC although allowed in
11234 return rets;/* is invalid in SDCC although allowed in ANSI */
11240 \begin_inset LatexCommand \index{long long (not supported)}
11245 \begin_inset LatexCommand \index{int (64 bit) (not supported)}
11253 \begin_inset LatexCommand \index{double (not supported)}
11257 ' precision floating point
11258 \begin_inset LatexCommand \index{Floating point support}
11265 No support for setjmp and longjmp (for now).
11269 \begin_inset LatexCommand \index{K\&R style}
11273 function declarations are NOT allowed.
11279 foo(i,j) /* this old style of function declarations */
11281 int i,j; /* are valid in ANSI but not valid in SDCC */
11295 functions declared as pointers must be dereferenced during the call.
11306 /* has to be called like this */
11308 (*foo)(); /* ansi standard allows calls to be made like 'foo()' */
11311 Cyclomatic Complexity
11312 \begin_inset LatexCommand \index{Cyclomatic complexity}
11319 Cyclomatic complexity of a function is defined as the number of independent
11320 paths the program can take during execution of the function.
11321 This is an important number since it defines the number test cases you
11322 have to generate to validate the function.
11323 The accepted industry standard for complexity number is 10, if the cyclomatic
11324 complexity reported by SDCC exceeds 10 you should think about simplification
11325 of the function logic.
11326 Note that the complexity level is not related to the number of lines of
11327 code in a function.
11328 Large functions can have low complexity, and small functions can have large
11334 SDCC uses the following formula to compute the complexity:
11339 complexity = (number of edges in control flow graph) - (number of nodes
11340 in control flow graph) + 2;
11344 Having said that the industry standard is 10, you should be aware that in
11345 some cases it be may unavoidable to have a complexity level of less than
11347 For example if you have switch statement with more than 10 case labels,
11348 each case label adds one to the complexity level.
11349 The complexity level is by no means an absolute measure of the algorithmic
11350 complexity of the function, it does however provide a good starting point
11351 for which functions you might look at for further optimization.
11357 Here are a few guidelines that will help the compiler generate more efficient
11358 code, some of the tips are specific to this compiler others are generally
11359 good programming practice.
11362 Use the smallest data type to represent your data-value.
11363 If it is known in advance that the value is going to be less than 256 then
11364 use an 'unsigned char' instead of a 'short' or 'int'.
11367 Use unsigned when it is known in advance that the value is not going to
11369 This helps especially if you are doing division or multiplication.
11372 NEVER jump into a LOOP.
11375 Declare the variables to be local whenever possible, especially loop control
11376 variables (induction).
11379 Since the compiler does not always do implicit integral promotion, the programme
11380 r should do an explicit cast when integral promotion is required.
11383 Reducing the size of division, multiplication & modulus operations can reduce
11384 code size substantially.
11385 Take the following code for example.
11391 foobar(unsigned int p1, unsigned char ch)
11395 unsigned char ch1 = p1 % ch ;
11406 For the modulus operation the variable ch will be promoted to unsigned int
11407 first then the modulus operation will be performed (this will lead to a
11408 call to support routine _moduint()), and the result will be casted to a
11410 If the code is changed to
11416 foobar(unsigned int p1, unsigned char ch)
11420 unsigned char ch1 = (unsigned char)p1 % ch ;
11431 It would substantially reduce the code generated (future versions of the
11432 compiler will be smart enough to detect such optimization oppurtunities).
11435 Notes on MCS51 memory
11436 \begin_inset LatexCommand \index{MCS51 memory}
11443 The 8051 family of microcontrollers have a minimum of 128 bytes of internal
11444 RAM memory which is structured as follows
11448 - Bytes 00-1F - 32 bytes to hold up to 4 banks of the registers R0 to R7,
11451 - Bytes 20-2F - 16 bytes to hold 128 bit variables and,
11453 - Bytes 30-7F - 80 bytes for general purpose use.
11458 Adittionally some members of the MCS51 family may have up to 128 bytes of
11459 additional, indirectly addressable, internal RAM memory (
11464 Furtermore, some chips may have some built in external memory (
11468 ) which should not be confused with the internal, direclty addressable RAM
11474 Usually this built in
11478 memory has to be activated before using it (you can probably find this
11479 information on the datasheet of the microcontroller your are using).
11482 Normally SDCC will only use the first bank
11483 \begin_inset LatexCommand \index{bank}
11487 of registers (register bank 0), but it is possible to specify that other
11488 banks of registers should be used in interrupt
11489 \begin_inset LatexCommand \index{interrupt}
11494 By default, the compiler will place the stack after the last byte of allocated
11495 memory for variables.
11496 For example, if the first 2 banks of registers are used, and only four
11501 variables, it will position the base of the internal stack at address 20
11503 This implies that as the stack
11504 \begin_inset LatexCommand \index{stack}
11508 grows, it will use up the remaining register banks, and the 16 bytes used
11509 by the 128 bit variables, and 80 bytes for general purpose use.
11510 If any bit variables are used, the data variables will be placed after
11511 the byte holding the last bit variable.
11512 For example, if register banks 0 and 1 are used, and there are 9 bit variables
11517 variables will be placed starting at address 0x22.
11529 \begin_inset LatexCommand \index{-\/-data-loc}
11533 to specify the start address of the
11547 -iram-size to specify the size of the total internal RAM (
11559 By default the 8051 linker will place the stack after the last byte of data
11572 \begin_inset LatexCommand \index{-\/-stack-loc}
11576 allows you to specify the start of the stack, i.e.
11577 you could start it after any data in the general purpose area.
11578 If your microcontroller has aditional indirectly addressable internal RAM
11583 ) you can place the stack on it.
11584 You may also need to use -
11595 \begin_inset LatexCommand \index{-\/-data-loc}
11599 to set the start address of the external RAM (
11614 \begin_inset LatexCommand \index{-\/-data-loc}
11618 to specify its size.
11619 Same goes for the code memory, using -
11630 \begin_inset LatexCommand \index{-\/-data-loc}
11645 \begin_inset LatexCommand \index{-\/-data-loc}
11650 If in doubt, don't specify any options and see if the resulting memory
11651 layout is appropiate, then you can twik it.
11654 The 8051 linker generates two files with memory allocation information.
11655 The first, with extension .map shows all the variables and segments.
11656 The second with extension .mem shows the final memory layout.
11657 The linker will complaint either if memory segments overlap, there is not
11658 enough memory, or there is not enough space for stack.
11659 If you get any linking warnings and/or errors related to stack or segments
11660 allocation, take a look at either the .map or .mem files to find out what
11662 The .mem file may even suggest a solution to the problem.
11666 \begin_inset LatexCommand \index{Tools}
11670 included in the distribution
11674 \begin_inset Tabular
11675 <lyxtabular version="3" rows="12" columns="3">
11677 <column alignment="center" valignment="top" leftline="true" width="0pt">
11678 <column alignment="center" valignment="top" leftline="true" width="0pt">
11679 <column alignment="center" valignment="top" leftline="true" rightline="true" width="0pt">
11680 <row topline="true" bottomline="true">
11681 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
11689 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
11697 <cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
11706 <row topline="true">
11707 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
11715 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
11720 Simulator for various architectures
11723 <cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
11732 <row topline="true">
11733 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
11741 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
11746 header file conversion
11749 <cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
11754 sdcc/support/scripts
11758 <row topline="true">
11759 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
11767 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
11772 header file conversion
11775 <cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
11780 sdcc/support/scripts
11784 <row topline="true">
11785 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
11793 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
11801 <cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
11819 <row topline="true">
11820 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
11828 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
11836 <cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
11854 <row topline="true">
11855 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
11863 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
11871 <cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
11889 <row topline="true">
11890 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
11898 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
11906 <cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
11924 <row topline="true" bottomline="true">
11925 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
11933 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
11941 <cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
11959 <row topline="true" bottomline="true">
11960 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
11968 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
11976 <cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
11994 <row topline="true" bottomline="true">
11995 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
12003 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
12011 <cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
12029 <row topline="true" bottomline="true">
12030 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
12038 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
12046 <cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
12071 Related open source tools
12072 \begin_inset LatexCommand \index{Related tools}
12080 \begin_inset Tabular
12081 <lyxtabular version="3" rows="7" columns="3">
12083 <column alignment="center" valignment="top" leftline="true" width="0pt">
12084 <column alignment="center" valignment="top" leftline="true" width="0pt">
12085 <column alignment="center" valignment="top" leftline="true" rightline="true" width="0pt">
12086 <row topline="true" bottomline="true">
12087 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
12095 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
12103 <cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
12112 <row topline="true">
12113 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
12119 \begin_inset LatexCommand \index{gpsim}
12126 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
12134 <cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
12140 \begin_inset LatexCommand \url{http://www.dattalo.com/gnupic/gpsim.html}
12148 <row topline="true">
12149 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
12155 \begin_inset LatexCommand \index{srecord}
12162 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
12167 Object file conversion, checksumming, ...
12170 <cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
12176 \begin_inset LatexCommand \url{http://srecord.sourceforge.net/}
12184 <row topline="true">
12185 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
12191 \begin_inset LatexCommand \index{objdump}
12198 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
12203 Object file conversion, ...
12206 <cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
12211 Part of binutils (should be there anyway)
12215 <row topline="true">
12216 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
12222 \begin_inset LatexCommand \index{doxygen}
12229 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
12234 Source code documentation system
12237 <cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
12243 \begin_inset LatexCommand \url{http://www.doxygen.org}
12251 <row topline="true">
12252 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
12258 \begin_inset LatexCommand \index{splint}
12265 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
12270 Statically checks c sources
12273 <cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
12279 \begin_inset LatexCommand \url{http://www.splint.org}
12287 <row topline="true" bottomline="true">
12288 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
12294 \begin_inset LatexCommand \index{ddd}
12301 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
12306 Debugger, serves nicely as GUI to sdcdb
12307 \begin_inset LatexCommand \index{sdcdb}
12314 <cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
12320 \begin_inset LatexCommand \url{http://www.gnu.org/software/ddd/}
12335 Related documentation / recommended reading
12339 \begin_inset Tabular
12340 <lyxtabular version="3" rows="5" columns="3">
12342 <column alignment="center" valignment="top" leftline="true" width="0pt">
12343 <column alignment="center" valignment="top" leftline="true" width="0pt">
12344 <column alignment="center" valignment="top" leftline="true" rightline="true" width="0pt">
12345 <row topline="true" bottomline="true">
12346 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
12354 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
12362 <cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
12371 <row topline="true">
12372 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
12382 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
12387 Advanced Compiler Design and Implementation
12390 <cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
12399 <row topline="true">
12400 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
12417 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
12423 \begin_inset LatexCommand \index{C Reference card}
12430 <cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
12436 \begin_inset LatexCommand \url{http://www.refcards.com/about/c.html}
12444 <row topline="true">
12445 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
12450 test_suite_spec.pdf
12453 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
12458 sdcc regression test
12459 \begin_inset LatexCommand \index{Regression test}
12466 <cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
12475 <row topline="true" bottomline="true">
12476 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
12502 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
12507 sdcc internal documentation
12510 <cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
12526 Retargetting for other MCUs.
12529 The issues for retargetting the compiler are far too numerous to be covered
12531 What follows is a brief description of each of the seven phases of the
12532 compiler and its MCU dependency.
12535 Parsing the source and building the annotated parse tree.
12536 This phase is largely MCU independent (except for the language extensions).
12537 Syntax & semantic checks are also done in this phase, along with some initial
12538 optimizations like back patching labels and the pattern matching optimizations
12539 like bit-rotation etc.
12542 The second phase involves generating an intermediate code which can be easy
12543 manipulated during the later phases.
12544 This phase is entirely MCU independent.
12545 The intermediate code generation assumes the target machine has unlimited
12546 number of registers, and designates them with the name iTemp.
12547 The compiler can be made to dump a human readable form of the code generated
12561 This phase does the bulk of the standard optimizations and is also MCU independe
12563 This phase can be broken down into several sub-phases:
12567 Break down intermediate code (iCode) into basic blocks.
12569 Do control flow & data flow analysis on the basic blocks.
12571 Do local common subexpression elimination, then global subexpression elimination
12573 Dead code elimination
12577 If loop optimizations caused any changes then do 'global subexpression eliminati
12578 on' and 'dead code elimination' again.
12581 This phase determines the live-ranges; by live range I mean those iTemp
12582 variables defined by the compiler that still survive after all the optimization
12584 Live range analysis
12585 \begin_inset LatexCommand \index{Live range analysis}
12589 is essential for register allocation, since these computation determines
12590 which of these iTemps will be assigned to registers, and for how long.
12593 Phase five is register allocation.
12594 There are two parts to this process.
12598 The first part I call 'register packing' (for lack of a better term).
12599 In this case several MCU specific expression folding is done to reduce
12604 The second part is more MCU independent and deals with allocating registers
12605 to the remaining live ranges.
12606 A lot of MCU specific code does creep into this phase because of the limited
12607 number of index registers available in the 8051.
12610 The Code generation phase is (unhappily), entirely MCU dependent and very
12611 little (if any at all) of this code can be reused for other MCU.
12612 However the scheme for allocating a homogenized assembler operand for each
12613 iCode operand may be reused.
12616 As mentioned in the optimization section the peep-hole optimizer is rule
12617 based system, which can reprogrammed for other MCUs.
12621 \begin_inset LatexCommand \index{sdcdb}
12625 - Source Level Debugger
12626 \begin_inset LatexCommand \index{Debugger}
12633 SDCC is distributed with a source level debugger.
12634 The debugger uses a command line interface, the command repertoire of the
12635 debugger has been kept as close to gdb
12636 \begin_inset LatexCommand \index{gdb}
12640 (the GNU debugger) as possible.
12641 The configuration and build process is part of the standard compiler installati
12642 on, which also builds and installs the debugger in the target directory
12643 specified during configuration.
12644 The debugger allows you debug BOTH at the C source and at the ASM source
12648 Compiling for Debugging
12651 The \SpecialChar \-
12653 debug option must be specified for all files for which debug information
12654 is to be generated.
12655 The complier generates a .adb file for each of these files.
12656 The linker creates the .cdb file from the .adb files and the address information.
12657 This .cdb is used by the debugger.
12660 How the Debugger Works
12673 -debug option is specified the compiler generates extra symbol information
12674 some of which are put into the the assembler source and some are put into
12676 Then the linker creates the .cdb file from the individual .adb files with
12677 the address information for the symbols.
12678 The debugger reads the symbolic information generated by the compiler &
12679 the address information generated by the linker.
12680 It uses the SIMULATOR (Daniel's S51) to execute the program, the program
12681 execution is controlled by the debugger.
12682 When a command is issued for the debugger, it translates it into appropriate
12683 commands for the simulator.
12686 Starting the Debugger
12689 The debugger can be started using the following command line.
12690 (Assume the file you are debugging has the file name foo).
12704 The debugger will look for the following files.
12707 foo.c - the source file.
12710 foo.cdb - the debugger symbol information file.
12713 foo.ihx - the intel hex format
12714 \begin_inset LatexCommand \index{Intel hex format}
12721 Command Line Options.
12734 -directory=<source file directory> this option can used to specify the directory
12736 The debugger will look into the directory list specified for source, cdb
12738 The items in the directory list must be separated by ':', e.g.
12739 if the source files can be in the directories /home/src1 and /home/src2,
12750 -directory option should be -
12760 -directory=/home/src1:/home/src2.
12761 Note there can be no spaces in the option.
12765 -cd <directory> - change to the <directory>.
12768 -fullname - used by GUI front ends.
12771 -cpu <cpu-type> - this argument is passed to the simulator please see the
12772 simulator docs for details.
12775 -X <Clock frequency > this options is passed to the simulator please see
12776 the simulator docs for details.
12779 -s <serial port file> passed to simulator see the simulator docs for details.
12782 -S <serial in,out> passed to simulator see the simulator docs for details.
12788 As mention earlier the command interface for the debugger has been deliberately
12789 kept as close the GNU debugger gdb, as possible.
12790 This will help the integration with existing graphical user interfaces
12791 (like ddd, xxgdb or xemacs) existing for the GNU debugger.
12792 \layout Subsubsection
12794 break [line | file:line | function | file:function]
12797 Set breakpoint at specified line or function:
12806 sdcdb>break foo.c:100
12808 sdcdb>break funcfoo
12810 sdcdb>break foo.c:funcfoo
12811 \layout Subsubsection
12813 clear [line | file:line | function | file:function ]
12816 Clear breakpoint at specified line or function:
12825 sdcdb>clear foo.c:100
12827 sdcdb>clear funcfoo
12829 sdcdb>clear foo.c:funcfoo
12830 \layout Subsubsection
12835 Continue program being debugged, after breakpoint.
12836 \layout Subsubsection
12841 Execute till the end of the current function.
12842 \layout Subsubsection
12847 Delete breakpoint number 'n'.
12848 If used without any option clear ALL user defined break points.
12849 \layout Subsubsection
12851 info [break | stack | frame | registers ]
12854 info break - list all breakpoints
12857 info stack - show the function call stack.
12860 info frame - show information about the current execution frame.
12863 info registers - show content of all registers.
12864 \layout Subsubsection
12869 Step program until it reaches a different source line.
12870 \layout Subsubsection
12875 Step program, proceeding through subroutine calls.
12876 \layout Subsubsection
12881 Start debugged program.
12882 \layout Subsubsection
12887 Print type information of the variable.
12888 \layout Subsubsection
12893 print value of variable.
12894 \layout Subsubsection
12899 load the given file name.
12900 Note this is an alternate method of loading file for debugging.
12901 \layout Subsubsection
12906 print information about current frame.
12907 \layout Subsubsection
12912 Toggle between C source & assembly source.
12913 \layout Subsubsection
12915 ! simulator command
12918 Send the string following '!' to the simulator, the simulator response is
12920 Note the debugger does not interpret the command being sent to the simulator,
12921 so if a command like 'go' is sent the debugger can loose its execution
12922 context and may display incorrect values.
12923 \layout Subsubsection
12930 My name is Bobby Brown"
12933 Interfacing with XEmacs
12934 \begin_inset LatexCommand \index{XEmacs}
12939 \begin_inset LatexCommand \index{Emacs}
12946 Two files (in emacs lisp) are provided for the interfacing with XEmacs,
12947 sdcdb.el and sdcdbsrc.el.
12948 These two files can be found in the $(prefix)/bin directory after the installat
12950 These files need to be loaded into XEmacs for the interface to work.
12951 This can be done at XEmacs startup time by inserting the following into
12952 your '.xemacs' file (which can be found in your HOME directory):
12958 (load-file sdcdbsrc.el)
12964 .xemacs is a lisp file so the () around the command is REQUIRED.
12965 The files can also be loaded dynamically while XEmacs is running, set the
12966 environment variable 'EMACSLOADPATH' to the installation bin directory
12967 (<installdir>/bin), then enter the following command ESC-x load-file sdcdbsrc.
12968 To start the interface enter the following command:
12982 You will prompted to enter the file name to be debugged.
12987 The command line options that are passed to the simulator directly are bound
12988 to default values in the file sdcdbsrc.el.
12989 The variables are listed below, these values maybe changed as required.
12992 sdcdbsrc-cpu-type '51
12995 sdcdbsrc-frequency '11059200
12998 sdcdbsrc-serial nil
13001 The following is a list of key mapping for the debugger interface.
13009 ;; Current Listing ::
13011 ;;key\SpecialChar ~
13026 binding\SpecialChar ~
13050 ;;---\SpecialChar ~
13065 ------\SpecialChar ~
13105 sdcdb-next-from-src\SpecialChar ~
13131 sdcdb-back-from-src\SpecialChar ~
13157 sdcdb-cont-from-src\SpecialChar ~
13167 SDCDB continue command
13183 sdcdb-step-from-src\SpecialChar ~
13209 sdcdb-whatis-c-sexp\SpecialChar ~
13219 SDCDB ptypecommand for data at
13283 sdcdbsrc-delete\SpecialChar ~
13297 SDCDB Delete all breakpoints if no arg
13345 given or delete arg (C-u arg x)
13361 sdcdbsrc-frame\SpecialChar ~
13376 SDCDB Display current frame if no arg,
13425 given or display frame arg
13490 sdcdbsrc-goto-sdcdb\SpecialChar ~
13500 Goto the SDCDB output buffer
13516 sdcdb-print-c-sexp\SpecialChar ~
13527 SDCDB print command for data at
13591 sdcdbsrc-goto-sdcdb\SpecialChar ~
13601 Goto the SDCDB output buffer
13617 sdcdbsrc-mode\SpecialChar ~
13633 Toggles Sdcdbsrc mode (turns it off)
13637 ;; C-c C-f\SpecialChar ~
13645 sdcdb-finish-from-src\SpecialChar ~
13653 SDCDB finish command
13657 ;; C-x SPC\SpecialChar ~
13665 sdcdb-break\SpecialChar ~
13683 Set break for line with point
13685 ;; ESC t\SpecialChar ~
13695 sdcdbsrc-mode\SpecialChar ~
13711 Toggle Sdcdbsrc mode
13713 ;; ESC m\SpecialChar ~
13723 sdcdbsrc-srcmode\SpecialChar ~
13747 The Z80 and gbz80 port
13750 SDCC can target both the Zilog Z80 and the Nintendo Gameboy's Z80-like gbz80.
13751 The port is incomplete - long support is incomplete (mul, div and mod are
13752 unimplimented), and both float and bitfield support is missing.
13753 Apart from that the code generated is correct.
13756 As always, the code is the authoritave reference - see z80/ralloc.c and z80/gen.c.
13757 The stack frame is similar to that generated by the IAR Z80 compiler.
13758 IX is used as the base pointer, HL is used as a temporary register, and
13759 BC and DE are available for holding varibles.
13760 IY is currently unusued.
13761 Return values are stored in HL.
13762 One bad side effect of using IX as the base pointer is that a functions
13763 stack frame is limited to 127 bytes - this will be fixed in a later version.
13767 \begin_inset LatexCommand \index{Support}
13774 SDCC has grown to be a large project.
13775 The compiler alone (without the preprocessor, assembler and linker) is
13776 about 40,000 lines of code (blank stripped).
13777 The open source nature of this project is a key to its continued growth
13779 You gain the benefit and support of many active software developers and
13781 Is SDCC perfect? No, that's why we need your help.
13782 The developers take pride in fixing reported bugs.
13783 You can help by reporting the bugs and helping other SDCC users.
13784 There are lots of ways to contribute, and we encourage you to take part
13785 in making SDCC a great software package.
13789 The SDCC project is hosted on the sdcc sourceforge site at
13790 \begin_inset LatexCommand \htmlurl{http://sourceforge.net/projects/sdcc}
13795 You'll find the complete set of mailing lists
13796 \begin_inset LatexCommand \index{Mailing list}
13800 , forums, bug reporting system, patch submission
13801 \begin_inset LatexCommand \index{Patch submission}
13806 \begin_inset LatexCommand \index{download}
13810 area and cvs code repository
13811 \begin_inset LatexCommand \index{cvs code repository}
13819 \begin_inset LatexCommand \index{Bugs}
13824 \begin_inset LatexCommand \index{Reporting bugs}
13831 The recommended way of reporting bugs is using the infrastructure of the
13833 You can follow the status of bug reports there and have an overview about
13837 Bug reports are automatically forwarded to the developer mailing list and
13838 will be fixed ASAP.
13839 When reporting a bug, it is very useful to include a small test program
13840 which reproduces the problem.
13841 If you can isolate the problem by looking at the generated assembly code,
13842 this can be very helpful.
13843 Compiling your program with the -
13854 \begin_inset LatexCommand \index{-\/-dumpall}
13858 option can sometimes be useful in locating optimization problems.
13861 Please have a short check that you are using a recent version of SDCC and
13862 the bug is not yet known.
13863 This is the link for reporting bugs:
13864 \begin_inset LatexCommand \htmlurl{http://sourceforge.net/tracker/?group_id=599&atid=100599}
13871 Requesting Features
13872 \begin_inset LatexCommand \index{Feature request}
13877 \begin_inset LatexCommand \index{Requesting features}
13884 Like bug reports feature requests are forwarded to the developer mailing
13886 This is the link for requesting features:
13887 \begin_inset LatexCommand \htmlurl{http://sourceforge.net/tracker/?group_id=599&atid=350599}
13897 These links should take you directly to the
13898 \begin_inset LatexCommand \url[Mailing lists]{http://sourceforge.net/mail/?group_id=599}
13908 Traffic on sdcc-devel and sdcc-user is about 100 mails/month each not counting
13909 automated messages (mid 2003)
13913 \begin_inset LatexCommand \url[Forums]{http://sourceforge.net/forum/?group_id=599}
13917 , lists and forums are archived so if you are lucky someone already had
13922 \begin_inset LatexCommand \index{Changelog}
13929 You can follow the status of the cvs version
13930 \begin_inset LatexCommand \index{version}
13934 of SDCC by watching the file
13935 \begin_inset LatexCommand \htmlurl[ChangeLog]{http://cvs.sourceforge.net/cgi-bin/viewcvs.cgi/*checkout*/sdcc/sdcc/ChangeLog?rev=HEAD&content-type=text/plain}
13939 in the cvs-repository.
13943 \begin_inset LatexCommand \index{Release policy}
13950 Historically there often were long delays between official releases and
13951 the sourceforge download area tends to get not updated at all.
13952 Current excuses might refer to problems with live range analysis, but if
13953 this is fixed, the next problem rising is that another excuse will have
13955 Kidding aside, we have to get better there!
13959 \begin_inset LatexCommand \index{Examples}
13966 You'll find some small examples in the directory sdcc/device/examples/
13969 Maybe we should include some links to real world applications.
13970 Preferrably pointer to pointers (one for each architecture) so this stays
13975 \begin_inset LatexCommand \index{Quality control}
13982 The compiler is passed through nightly compile and build checks.
13988 \begin_inset LatexCommand \index{Regression test}
13992 check that SDCC itself compiles flawlessly on several platforms and checks
13993 the quality of the code generated by SDCC by running the code through simulator
13995 There is a separate document
13998 \begin_inset LatexCommand \index{Test suite}
14007 You'll find the test code in the directory
14009 sdcc/support/regression
14012 You can run these tests manually by running
14016 in this directory (or f.e.
14021 if you don't want to run the complete tests).
14022 The test code might also be interesting if you want to look for examples
14023 \begin_inset LatexCommand \index{Examples}
14027 checking corner cases of SDCC or if you plan to submit patches
14028 \begin_inset LatexCommand \index{Patch submission}
14035 The pic port uses a different set of regression tests, you'll find them
14038 sdcc/src/regression
14044 \begin_inset LatexCommand \index{Compiler internals}
14051 The anatomy of the compiler
14056 This is an excerpt from an atricle published in Circuit Cellar MagaZine
14058 It's a little outdated (the compiler is much more efficient now and user/develo
14059 per friendly), but pretty well exposes the guts of it all.
14065 The current version of SDCC can generate code for Intel 8051 and Z80 MCU.
14066 It is fairly easy to retarget for other 8-bit MCU.
14067 Here we take a look at some of the internals of the compiler.
14072 \begin_inset LatexCommand \index{Parsing}
14079 Parsing the input source file and creating an AST (Annotated Syntax Tree
14080 \begin_inset LatexCommand \index{Annotated syntax tree}
14085 This phase also involves propagating types (annotating each node of the
14086 parse tree with type information) and semantic analysis.
14087 There are some MCU specific parsing rules.
14088 For example the storage classes, the extended storage classes are MCU specific
14089 while there may be a xdata storage class for 8051 there is no such storage
14090 class for z80 or Atmel AVR.
14091 SDCC allows MCU specific storage class extensions, i.e.
14092 xdata will be treated as a storage class specifier when parsing 8051 C
14093 code but will be treated as a C identifier when parsing z80 or ATMEL AVR
14098 \begin_inset LatexCommand \index{iCode}
14105 Intermediate code generation.
14106 In this phase the AST is broken down into three-operand form (iCode).
14107 These three operand forms are represented as doubly linked lists.
14108 ICode is the term given to the intermediate form generated by the compiler.
14109 ICode example section shows some examples of iCode generated for some simple
14110 C source functions.
14114 \begin_inset LatexCommand \index{Optimizations}
14121 Bulk of the target independent optimizations is performed in this phase.
14122 The optimizations include constant propagation, common sub-expression eliminati
14123 on, loop invariant code movement, strength reduction of loop induction variables
14124 and dead-code elimination.
14127 Live range analysis
14128 \begin_inset LatexCommand \index{Live range analysis}
14135 During intermediate code generation phase, the compiler assumes the target
14136 machine has infinite number of registers and generates a lot of temporary
14138 The live range computation determines the lifetime of each of these compiler-ge
14139 nerated temporaries.
14140 A picture speaks a thousand words.
14141 ICode example sections show the live range annotations for each of the
14143 It is important to note here, each iCode is assigned a number in the order
14144 of its execution in the function.
14145 The live ranges are computed in terms of these numbers.
14146 The from number is the number of the iCode which first defines the operand
14147 and the to number signifies the iCode which uses this operand last.
14150 Register Allocation
14151 \begin_inset LatexCommand \index{Register allocation}
14158 The register allocation determines the type and number of registers needed
14160 In most MCUs only a few registers can be used for indirect addressing.
14161 In case of 8051 for example the registers R0 & R1 can be used to indirectly
14162 address the internal ram and DPTR to indirectly address the external ram.
14163 The compiler will try to allocate the appropriate register to pointer variables
14165 ICode example section shows the operands annotated with the registers assigned
14167 The compiler will try to keep operands in registers as much as possible;
14168 there are several schemes the compiler uses to do achieve this.
14169 When the compiler runs out of registers the compiler will check to see
14170 if there are any live operands which is not used or defined in the current
14171 basic block being processed, if there are any found then it will push that
14172 operand and use the registers in this block, the operand will then be popped
14173 at the end of the basic block.
14177 There are other MCU specific considerations in this phase.
14178 Some MCUs have an accumulator; very short-lived operands could be assigned
14179 to the accumulator instead of general-purpose register.
14185 Figure II gives a table of iCode operations supported by the compiler.
14186 The code generation involves translating these operations into corresponding
14187 assembly code for the processor.
14188 This sounds overly simple but that is the essence of code generation.
14189 Some of the iCode operations are generated on a MCU specific manner for
14190 example, the z80 port does not use registers to pass parameters so the
14191 SEND and RECV iCode operations will not be generated, and it also does
14192 not support JUMPTABLES.
14199 <Where is Figure II ?>
14203 \begin_inset LatexCommand \index{iCode}
14210 This section shows some details of iCode.
14211 The example C code does not do anything useful; it is used as an example
14212 to illustrate the intermediate code generated by the compiler.
14225 /* This function does nothing useful.
14232 for the purpose of explaining iCode */
14235 short function (data int *x)
14243 short i=10; /* dead initialization eliminated */
14248 short sum=10; /* dead initialization eliminated */
14261 while (*x) *x++ = *p++;
14275 /* compiler detects i,j to be induction variables */
14279 for (i = 0, j = 10 ; i < 10 ; i++, j--) {
14291 mul += i * 3; /* this multiplication remains */
14297 gint += j * 3;/* this multiplication changed to addition */
14314 In addition to the operands each iCode contains information about the filename
14315 and line it corresponds to in the source file.
14316 The first field in the listing should be interpreted as follows:
14321 Filename(linenumber: iCode Execution sequence number : ICode hash table
14322 key : loop depth of the iCode).
14327 Then follows the human readable form of the ICode operation.
14328 Each operand of this triplet form can be of three basic types a) compiler
14329 generated temporary b) user defined variable c) a constant value.
14330 Note that local variables and parameters are replaced by compiler generated
14333 \begin_inset LatexCommand \index{Live range analysis}
14337 are computed only for temporaries (i.e.
14338 live ranges are not computed for global variables).
14340 \begin_inset LatexCommand \index{Register allocation}
14344 are allocated for temporaries only.
14345 Operands are formatted in the following manner:
14350 Operand Name [lr live-from : live-to ] { type information } [ registers
14356 As mentioned earlier the live ranges are computed in terms of the execution
14357 sequence number of the iCodes, for example
14359 the iTemp0 is live from (i.e.
14360 first defined in iCode with execution sequence number 3, and is last used
14361 in the iCode with sequence number 5).
14362 For induction variables such as iTemp21 the live range computation extends
14363 the lifetime from the start to the end of the loop.
14365 The register allocator used the live range information to allocate registers,
14366 the same registers may be used for different temporaries if their live
14367 ranges do not overlap, for example r0 is allocated to both iTemp6 and to
14368 iTemp17 since their live ranges do not overlap.
14369 In addition the allocator also takes into consideration the type and usage
14370 of a temporary, for example itemp6 is a pointer to near space and is used
14371 as to fetch data from (i.e.
14372 used in GET_VALUE_AT_ADDRESS) so it is allocated a pointer registers (r0).
14373 Some short lived temporaries are allocated to special registers which have
14374 meaning to the code generator e.g.
14375 iTemp13 is allocated to a pseudo register CC which tells the back end that
14376 the temporary is used only for a conditional jump the code generation makes
14377 use of this information to optimize a compare and jump ICode.
14379 There are several loop optimizations
14380 \begin_inset LatexCommand \index{Loop optimization}
14384 performed by the compiler.
14385 It can detect induction variables iTemp21(i) and iTemp23(j).
14386 Also note the compiler does selective strength reduction
14387 \begin_inset LatexCommand \index{Strength reduction}
14392 the multiplication of an induction variable in line 18 (gint = j * 3) is
14393 changed to addition, a new temporary iTemp17 is allocated and assigned
14394 a initial value, a constant 3 is then added for each iteration of the loop.
14395 The compiler does not change the multiplication
14396 \begin_inset LatexCommand \index{Multiplication}
14400 in line 17 however since the processor does support an 8 * 8 bit multiplication.
14402 Note the dead code elimination
14403 \begin_inset LatexCommand \index{Dead-code elimination}
14407 optimization eliminated the dead assignments in line 7 & 8 to I and sum
14415 Sample.c (5:1:0:0) _entry($9) :
14420 Sample.c(5:2:1:0) proc _function [lr0:0]{function short}
14425 Sample.c(11:3:2:0) iTemp0 [lr3:5]{_near * int}[r2] = recv
14430 Sample.c(11:4:53:0) preHeaderLbl0($11) :
14435 Sample.c(11:5:55:0) iTemp6 [lr5:16]{_near * int}[r0] := iTemp0 [lr3:5]{_near
14441 Sample.c(11:6:5:1) _whilecontinue_0($1) :
14446 Sample.c(11:7:7:1) iTemp4 [lr7:8]{int}[r2 r3] = @[iTemp6 [lr5:16]{_near *
14452 Sample.c(11:8:8:1) if iTemp4 [lr7:8]{int}[r2 r3] == 0 goto _whilebreak_0($3)
14457 Sample.c(11:9:14:1) iTemp7 [lr9:13]{_far * int}[DPTR] := _p [lr0:0]{_far
14463 Sample.c(11:10:15:1) _p [lr0:0]{_far * int} = _p [lr0:0]{_far * int} + 0x2
14469 Sample.c(11:13:18:1) iTemp10 [lr13:14]{int}[r2 r3] = @[iTemp7 [lr9:13]{_far
14475 Sample.c(11:14:19:1) *(iTemp6 [lr5:16]{_near * int}[r0]) := iTemp10 [lr13:14]{int
14481 Sample.c(11:15:12:1) iTemp6 [lr5:16]{_near * int}[r0] = iTemp6 [lr5:16]{_near
14482 * int}[r0] + 0x2 {short}
14487 Sample.c(11:16:20:1) goto _whilecontinue_0($1)
14492 Sample.c(11:17:21:0)_whilebreak_0($3) :
14497 Sample.c(12:18:22:0) iTemp2 [lr18:40]{short}[r2] := 0x0 {short}
14502 Sample.c(13:19:23:0) iTemp11 [lr19:40]{short}[r3] := 0x0 {short}
14507 Sample.c(15:20:54:0)preHeaderLbl1($13) :
14512 Sample.c(15:21:56:0) iTemp21 [lr21:38]{short}[r4] := 0x0 {short}
14517 Sample.c(15:22:57:0) iTemp23 [lr22:38]{int}[r5 r6] := 0xa {int}
14522 Sample.c(15:23:58:0) iTemp17 [lr23:38]{int}[r7 r0] := 0x1e {int}
14527 Sample.c(15:24:26:1)_forcond_0($4) :
14532 Sample.c(15:25:27:1) iTemp13 [lr25:26]{char}[CC] = iTemp21 [lr21:38]{short}[r4]
14538 Sample.c(15:26:28:1) if iTemp13 [lr25:26]{char}[CC] == 0 goto _forbreak_0($7)
14543 Sample.c(16:27:31:1) iTemp2 [lr18:40]{short}[r2] = iTemp2 [lr18:40]{short}[r2]
14544 + ITemp21 [lr21:38]{short}[r4]
14549 Sample.c(17:29:33:1) iTemp15 [lr29:30]{short}[r1] = iTemp21 [lr21:38]{short}[r4]
14555 Sample.c(17:30:34:1) iTemp11 [lr19:40]{short}[r3] = iTemp11 [lr19:40]{short}[r3]
14556 + iTemp15 [lr29:30]{short}[r1]
14561 Sample.c(18:32:36:1:1) iTemp17 [lr23:38]{int}[r7 r0]= iTemp17 [lr23:38]{int}[r7
14567 Sample.c(18:33:37:1) _gint [lr0:0]{int} = _gint [lr0:0]{int} + iTemp17 [lr23:38]{
14573 Sample.c(15:36:42:1) iTemp21 [lr21:38]{short}[r4] = iTemp21 [lr21:38]{short}[r4]
14579 Sample.c(15:37:45:1) iTemp23 [lr22:38]{int}[r5 r6]= iTemp23 [lr22:38]{int}[r5
14585 Sample.c(19:38:47:1) goto _forcond_0($4)
14590 Sample.c(19:39:48:0)_forbreak_0($7) :
14595 Sample.c(20:40:49:0) iTemp24 [lr40:41]{short}[DPTR] = iTemp2 [lr18:40]{short}[r2]
14596 + ITemp11 [lr19:40]{short}[r3]
14601 Sample.c(20:41:50:0) ret iTemp24 [lr40:41]{short}
14606 Sample.c(20:42:51:0)_return($8) :
14611 Sample.c(20:43:52:0) eproc _function [lr0:0]{ ia0 re0 rm0}{function short}
14617 Finally the code generated for this function:
14658 ; ----------------------------------------------
14663 ; function function
14668 ; ----------------------------------------------
14678 ; iTemp0 [lr3:5]{_near * int}[r2] = recv
14690 ; iTemp6 [lr5:16]{_near * int}[r0] := iTemp0 [lr3:5]{_near * int}[r2]
14702 ;_whilecontinue_0($1) :
14712 ; iTemp4 [lr7:8]{int}[r2 r3] = @[iTemp6 [lr5:16]{_near * int}[r0]]
14717 ; if iTemp4 [lr7:8]{int}[r2 r3] == 0 goto _whilebreak_0($3)
14776 ; iTemp7 [lr9:13]{_far * int}[DPTR] := _p [lr0:0]{_far * int}
14795 ; _p [lr0:0]{_far * int} = _p [lr0:0]{_far * int} + 0x2 {short}
14842 ; iTemp10 [lr13:14]{int}[r2 r3] = @[iTemp7 [lr9:13]{_far * int}[DPTR]]
14882 ; *(iTemp6 [lr5:16]{_near * int}[r0]) := iTemp10 [lr13:14]{int}[r2 r3]
14908 ; iTemp6 [lr5:16]{_near * int}[r0] =
14913 ; iTemp6 [lr5:16]{_near * int}[r0] +
14930 ; goto _whilecontinue_0($1)
14942 ; _whilebreak_0($3) :
14952 ; iTemp2 [lr18:40]{short}[r2] := 0x0 {short}
14964 ; iTemp11 [lr19:40]{short}[r3] := 0x0 {short}
14976 ; iTemp21 [lr21:38]{short}[r4] := 0x0 {short}
14988 ; iTemp23 [lr22:38]{int}[r5 r6] := 0xa {int}
15007 ; iTemp17 [lr23:38]{int}[r7 r0] := 0x1e {int}
15036 ; iTemp13 [lr25:26]{char}[CC] = iTemp21 [lr21:38]{short}[r4] < 0xa {short}
15041 ; if iTemp13 [lr25:26]{char}[CC] == 0 goto _forbreak_0($7)
15086 ; iTemp2 [lr18:40]{short}[r2] = iTemp2 [lr18:40]{short}[r2] +
15091 ; iTemp21 [lr21:38]{short}[r4]
15117 ; iTemp15 [lr29:30]{short}[r1] = iTemp21 [lr21:38]{short}[r4] * 0x3 {short}
15150 ; iTemp11 [lr19:40]{short}[r3] = iTemp11 [lr19:40]{short}[r3] +
15155 ; iTemp15 [lr29:30]{short}[r1]
15174 ; iTemp17 [lr23:38]{int}[r7 r0]= iTemp17 [lr23:38]{int}[r7 r0]- 0x3 {short}
15221 ; _gint [lr0:0]{int} = _gint [lr0:0]{int} + iTemp17 [lr23:38]{int}[r7 r0]
15268 ; iTemp21 [lr21:38]{short}[r4] = iTemp21 [lr21:38]{short}[r4] + 0x1 {short}
15280 ; iTemp23 [lr22:38]{int}[r5 r6]= iTemp23 [lr22:38]{int}[r5 r6]- 0x1 {short}
15294 cjne r5,#0xff,00104$
15306 ; goto _forcond_0($4)
15318 ; _forbreak_0($7) :
15328 ; ret iTemp24 [lr40:41]{short}
15371 A few words about basic block successors, predecessors and dominators
15374 Successors are basic blocks
15375 \begin_inset LatexCommand \index{Basic blocks}
15379 that might execute after this basic block.
15381 Predecessors are basic blocks that might execute before reaching this basic
15384 Dominators are basic blocks that WILL execute before reaching this basic
15410 a) succList of [BB2] = [BB4], of [BB3] = [BB4], of [BB1] = [BB2,BB3]
15413 b) predList of [BB2] = [BB1], of [BB3] = [BB1], of [BB4] = [BB2,BB3]
15416 c) domVect of [BB4] = BB1 ...
15417 here we are not sure if BB2 or BB3 was executed but we are SURE that BB1
15425 \begin_inset LatexCommand \url{http://sdcc.sourceforge.net#Who}
15435 Thanks to all the other volunteer developers who have helped with coding,
15436 testing, web-page creation, distribution sets, etc.
15437 You know who you are :-)
15444 This document was initially written by Sandeep Dutta
15447 All product names mentioned herein may be trademarks
15448 \begin_inset LatexCommand \index{Trademarks}
15452 of their respective companies.
15459 To avoid confusion, the installation and building options for sdcc itself
15460 (chapter 2) are not part of the index.
15464 \begin_inset LatexCommand \printindex{}