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 Building SDCC Using Microsoft Visual C++ 6.0/NET (MSVC)
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 (except for sdcdb.exe which currently
3028 doesn't build under MSVC).
3029 The workspace name is 'sdcc.dsw'.
3030 Please note that as it is now, all the executables are created in a folder
3034 Once built you need to copy the executables from sdcc
3038 bin before runing SDCC.
3043 In order to build SDCC with MSVC you need win32 executables of bison.exe,
3044 flex.exe, and gawk.exe.
3045 One good place to get them is
3046 \begin_inset LatexCommand \url[here]{http://unxutils.sourceforge.net}
3054 Download the file UnxUtils
3055 \begin_inset LatexCommand \index{UnxUtils}
3060 Now you have to install the utilities and setup MSVC so it can locate the
3062 Here there are two alternatives (choose one!):
3069 a) Extract UnxUtils.zip to your C:
3071 hard disk PRESERVING the original paths, otherwise bison won't work.
3072 (If you are using WinZip make certain that 'Use folder names' is selected)
3076 b) In the Visual C++ IDE click Tools, Options, select the Directory tab,
3077 in 'Show directories for:' select 'Executable files', and in the directories
3078 window add a new path: 'C:
3088 (As a side effect, you get a bunch of Unix utilities that could be useful,
3089 such as diff and patch.)
3096 This one avoids extracting a bunch of files you may not use, but requires
3101 a) Create a directory were to put the tools needed, or use a directory already
3109 b) Extract 'bison.exe', 'bison.hairy', 'bison.simple', 'flex.exe', and gawk.exe
3110 to such directory WITHOUT preserving the original paths.
3111 (If you are using WinZip make certain that 'Use folder names' is not selected)
3115 c) Rename bison.exe to '_bison.exe'.
3119 d) Create a batch file 'bison.bat' in 'C:
3123 ' and add these lines:
3143 _bison %1 %2 %3 %4 %5 %6 %7 %8 %9
3147 Steps 'c' and 'd' are needed because bison requires by default that the
3148 files 'bison.simple' and 'bison.hairy' reside in some weird Unix directory,
3149 '/usr/local/share/' I think.
3150 So it is necessary to tell bison where those files are located if they
3151 are not in such directory.
3152 That is the function of the environment variables BISON_SIMPLE and BISON_HAIRY.
3156 e) In the Visual C++ IDE click Tools, Options, select the Directory tab,
3157 in 'Show directories for:' select 'Executable files', and in the directories
3158 window add a new path: 'c:
3161 Note that you can use any other path instead of 'c:
3163 util', even the path where the Visual C++ tools are, probably: 'C:
3167 Microsoft Visual Studio
3172 So you don't have to execute step 'e' :)
3176 Open 'sdcc.dsw' in Visual Studio, click 'build all', when it finishes copy
3177 the executables from sdcc
3181 bin, and you can compile using sdcc.
3182 \layout Subsubsection
3184 Building SDCC Using Borland
3187 From the sdcc directory, run the command "make -f Makefile.bcc".
3188 This should regenerate all the .exe files in the bin directory except for
3189 sdcdb.exe (which currently doesn't build under Borland C++).
3192 If you modify any source files and need to rebuild, be aware that the dependanci
3193 es may not be correctly calculated.
3194 The safest option is to delete all .obj files and run the build again.
3195 From a Cygwin BASH prompt, this can easily be done with the commmand:
3205 ( -name '*.obj' -o -name '*.lib' -o -name '*.rul'
3207 ) -print -exec rm {}
3216 or on Windows NT/2000/XP from the command prompt with the commmand:
3223 del /s *.obj *.lib *.rul
3226 from the sdcc directory.
3229 Building the Documentation
3236 Testing out the SDCC Compiler
3239 The first thing you should do after installing your SDCC compiler is to
3255 \begin_inset LatexCommand \index{version}
3262 at the prompt, and the program should run and tell you the version.
3263 If it doesn't run, or gives a message about not finding sdcc program, then
3264 you need to check over your installation.
3265 Make sure that the sdcc bin directory is in your executable search path
3266 defined by the PATH environment setting (see the Trouble-shooting section
3268 Make sure that the sdcc program is in the bin folder, if not perhaps something
3269 did not install correctly.
3277 is commonly installed as described in section
3278 \begin_inset Quotes sld
3281 Install and search paths
3282 \begin_inset Quotes srd
3291 Make sure the compiler works on a very simple example.
3292 Type in the following test.c program using your favorite
3318 Compile this using the following command:
3327 If all goes well, the compiler will generate a test.asm and test.rel file.
3328 Congratulations, you've just compiled your first program with SDCC.
3329 We used the -c option to tell SDCC not to link the generated code, just
3330 to keep things simple for this step.
3338 The next step is to try it with the linker.
3348 If all goes well the compiler will link with the libraries and produce
3349 a test.ihx output file.
3354 (no test.ihx, and the linker generates warnings), then the problem is most
3355 likely that sdcc cannot find the
3359 usr/local/share/sdcc/lib directory
3363 (see the Install trouble-shooting section for suggestions).
3371 The final test is to ensure sdcc can use the
3375 header files and libraries.
3376 Edit test.c and change it to the following:
3393 strcpy(str1, "testing");
3400 Compile this by typing
3407 This should generate a test.ihx output file, and it should give no warnings
3408 such as not finding the string.h file.
3409 If it cannot find the string.h file, then the problem is that sdcc cannot
3410 find the /usr/local/share/sdcc/include directory
3414 (see the Install trouble-shooting section for suggestions).
3417 Install Trouble-shooting
3418 \begin_inset LatexCommand \index{Install trouble-shooting}
3423 \layout Subsubsection
3425 SDCC does not build correctly.
3428 A thing to try is starting from scratch by unpacking the .tgz source package
3429 again in an empty directory.
3437 ./configure 2>&1 | tee configure.log
3451 make 2>&1 | tee make.log
3458 If anything goes wrong, you can review the log files to locate the problem.
3459 Or a relevant part of this can be attached to an email that could be helpful
3460 when requesting help from the mailing list.
3461 \layout Subsubsection
3464 \begin_inset Quotes sld
3468 \begin_inset Quotes srd
3475 \begin_inset Quotes sld
3479 \begin_inset Quotes srd
3482 command is a script that analyzes your system and performs some configuration
3483 to ensure the source package compiles on your system.
3484 It will take a few minutes to run, and will compile a few tests to determine
3485 what compiler features are installed.
3486 \layout Subsubsection
3489 \begin_inset Quotes sld
3493 \begin_inset Quotes srd
3499 This runs the GNU make tool, which automatically compiles all the source
3500 packages into the final installed binary executables.
3501 \layout Subsubsection
3504 \begin_inset Quotes sld
3508 \begin_inset Quotes erd
3514 This will install the compiler, other executables libraries and include
3515 files in to the appropriate directories.
3517 \begin_inset Quotes sld
3520 Install and Search PATHS
3521 \begin_inset Quotes srd
3526 On most systems you will need super-user privilages to do this.
3532 SDCC is not just a compiler, but a collection of tools by various developers.
3533 These include linkers, assemblers, simulators and other components.
3534 Here is a summary of some of the components.
3535 Note that the included simulator and assembler have separate documentation
3536 which you can find in the source package in their respective directories.
3537 As SDCC grows to include support for other processors, other packages from
3538 various developers are included and may have their own sets of documentation.
3542 You might want to look at the files which are installed in <installdir>.
3543 At the time of this writing, we find the following programs for gcc-builds:
3547 In <installdir>/bin:
3550 sdcc - The compiler.
3553 sdcpp - The C preprocessor.
3556 asx8051 - The assembler for 8051 type processors.
3563 as-gbz80 - The Z80 and GameBoy Z80 assemblers.
3566 aslink -The linker for 8051 type processors.
3573 link-gbz80 - The Z80 and GameBoy Z80 linkers.
3576 s51 - The ucSim 8051 simulator.
3579 sdcdb - The source debugger.
3582 packihx - A tool to pack (compress) Intel hex files.
3585 In <installdir>/share/sdcc/include
3591 In <installdir>/share/sdcc/lib
3594 the subdirs src and small, large, z80, gbz80 and ds390 with the precompiled
3598 In <installdir>/share/sdcc/doc
3604 As development for other processors proceeds, this list will expand to include
3605 executables to support processors like AVR, PIC, etc.
3606 \layout Subsubsection
3611 This is the actual compiler, it in turn uses the c-preprocessor and invokes
3612 the assembler and linkage editor.
3613 \layout Subsubsection
3616 \begin_inset LatexCommand \index{sdcpp}
3620 - The C-Preprocessor
3623 The preprocessor is a modified version of the GNU preprocessor.
3624 The C preprocessor is used to pull in #include sources, process #ifdef
3625 statements, #defines and so on.
3626 \layout Subsubsection
3628 asx8051, as-z80, as-gbz80, aslink, link-z80, link-gbz80 - The Assemblers
3632 This is retargettable assembler & linkage editor, it was developed by Alan
3634 John Hartman created the version for 8051, and I (Sandeep) have made some
3635 enhancements and bug fixes for it to work properly with the SDCC.
3636 \layout Subsubsection
3639 \begin_inset LatexCommand \index{s51}
3646 S51 is a freeware, opensource simulator developed by Daniel Drotos (
3647 \begin_inset LatexCommand \url{mailto:drdani@mazsola.iit.uni-miskolc.hu}
3652 The simulator is built as part of the build process.
3653 For more information visit Daniel's website at:
3654 \begin_inset LatexCommand \url{http://mazsola.iit.uni-miskolc.hu/~drdani/embedded/s51}
3659 It currently support the core mcs51, the Dallas DS80C390 and the Philips
3661 \layout Subsubsection
3664 \begin_inset LatexCommand \index{sdcdb}
3668 - Source Level Debugger
3671 Sdcdb is the companion source level debugger.
3672 The current version of the debugger uses Daniel's Simulator S51, but can
3673 be easily changed to use other simulators.
3680 \layout Subsubsection
3682 Single Source File Projects
3685 For single source file 8051 projects the process is very simple.
3686 Compile your programs with the following command
3689 "sdcc sourcefile.c".
3693 This will compile, assemble and link your source file.
3694 Output files are as follows
3698 \begin_inset LatexCommand \index{.asm}
3703 \begin_inset LatexCommand \index{Assembler source}
3707 file created by the compiler
3711 \begin_inset LatexCommand \index{.lst}
3716 \begin_inset LatexCommand \index{Assembler listing}
3720 file created by the Assembler
3724 \begin_inset LatexCommand \index{.rst}
3729 \begin_inset LatexCommand \index{Assembler listing}
3733 file updated with linkedit information, created by linkage editor
3737 \begin_inset LatexCommand \index{.sym}
3742 \begin_inset LatexCommand \index{Symbol listing}
3746 for the sourcefile, created by the assembler
3750 \begin_inset LatexCommand \index{.rel}
3755 \begin_inset LatexCommand \index{Object file}
3759 created by the assembler, input to Linkage editor
3763 \begin_inset LatexCommand \index{.map}
3768 \begin_inset LatexCommand \index{Memory map}
3772 for the load module, created by the Linker
3776 \begin_inset LatexCommand \index{.mem}
3780 - A file with a summary of the memory usage
3784 \begin_inset LatexCommand \index{.ihx}
3788 - The load module in Intel hex format
3789 \begin_inset LatexCommand \index{Intel hex format}
3793 (you can select the Motorola S19 format
3794 \begin_inset LatexCommand \index{Motorola S19 format}
3809 \begin_inset LatexCommand \index{-\/-out-fmt-s19}
3814 If you need another format you might want to use objdump
3815 \begin_inset LatexCommand \index{objdump}
3820 \begin_inset LatexCommand \index{srecord}
3828 \begin_inset LatexCommand \index{.adb}
3832 - An intermediate file containing debug information needed to create the
3844 \begin_inset LatexCommand \index{-\/-debug}
3852 \begin_inset LatexCommand \index{.cdb}
3856 - An optional file (with -
3866 -debug) containing debug information
3871 \begin_inset LatexCommand \index{. (no extension)}
3875 An optional AOMF51 file containing debug information (with -
3889 \begin_inset LatexCommand \index{.dump*}
3893 - Dump file to debug the compiler it self (with -
3903 -dumpall) (see section
3904 \begin_inset Quotes sld
3907 Anatomy of the compiler
3908 \begin_inset Quotes srd
3912 \layout Subsubsection
3914 Projects with Multiple Source Files
3917 SDCC can compile only ONE file at a time.
3918 Let us for example assume that you have a project containing the following
3923 foo1.c (contains some functions)
3925 foo2.c (contains some more functions)
3927 foomain.c (contains more functions and the function main)
3935 The first two files will need to be compiled separately with the commands:
3967 Then compile the source file containing the
3972 \begin_inset LatexCommand \index{Linker}
3976 the files together with the following command:
3984 foomain.c\SpecialChar ~
3985 foo1.rel\SpecialChar ~
3990 \begin_inset LatexCommand \index{.rel}
4002 can be separately compiled as well:
4013 sdcc foomain.rel foo1.rel foo2.rel
4020 The file containing the
4035 file specified in the command line, since the linkage editor processes
4036 file in the order they are presented to it.
4037 \layout Subsubsection
4039 Projects with Additional Libraries
4040 \begin_inset LatexCommand \index{Libraries}
4047 Some reusable routines may be compiled into a library, see the documentation
4048 for the assembler and linkage editor (which are in <installdir>/share/sdcc/doc)
4052 \begin_inset LatexCommand \index{.lib}
4059 Libraries created in this manner can be included in the command line.
4060 Make sure you include the -L <library-path> option to tell the linker where
4061 to look for these files if they are not in the current directory.
4062 Here is an example, assuming you have the source file
4074 (if that is not the same as your current project):
4081 sdcc foomain.c foolib.lib -L mylib
4092 must be an absolute path name.
4096 The most efficient way to use libraries is to keep seperate modules in seperate
4098 The lib file now should name all the modules.rel files.
4099 For an example see the standard library file
4103 in the directory <installdir>/share/lib/small.
4106 Command Line Options
4107 \begin_inset LatexCommand \index{Command Line Options}
4112 \layout Subsubsection
4114 Processor Selection Options
4115 \begin_inset LatexCommand \index{Options processor selection}
4120 \begin_inset LatexCommand \index{Processor selection options}
4126 \labelwidthstring 00.00.0000
4131 \begin_inset LatexCommand \index{-mmcs51}
4137 Generate code for the MCS51
4138 \begin_inset LatexCommand \index{MCS51}
4142 family of processors.
4143 This is the default processor target.
4145 \labelwidthstring 00.00.0000
4150 \begin_inset LatexCommand \index{-mds390}
4156 Generate code for the DS80C390
4157 \begin_inset LatexCommand \index{DS80C390}
4163 \labelwidthstring 00.00.0000
4168 \begin_inset LatexCommand \index{-mds400}
4174 Generate code for the DS80C400
4175 \begin_inset LatexCommand \index{DS80C400}
4181 \labelwidthstring 00.00.0000
4186 \begin_inset LatexCommand \index{-mz80}
4192 Generate code for the Z80
4193 \begin_inset LatexCommand \index{Z80}
4197 family of processors.
4199 \labelwidthstring 00.00.0000
4204 \begin_inset LatexCommand \index{-mgbz80}
4210 Generate code for the GameBoy Z80
4211 \begin_inset LatexCommand \index{GameBoy Z80}
4217 \labelwidthstring 00.00.0000
4222 \begin_inset LatexCommand \index{-mavr}
4228 Generate code for the Atmel AVR
4229 \begin_inset LatexCommand \index{AVR}
4233 processor (In development, not complete).
4234 AVR users should probably have a look at avr-gcc
4235 \begin_inset LatexCommand \url[FIXME: official URL?]{ http://savannah.nongnu.org/download/avr-libc/snapshots/}
4242 I think it is fair to direct users there for now.
4243 Open source is also about avoiding unnecessary work .
4244 But I didn't find the 'official' link.
4246 \labelwidthstring 00.00.0000
4251 \begin_inset LatexCommand \index{-mpic14}
4257 Generate code for the PIC 14
4258 \begin_inset LatexCommand \index{PIC14}
4262 -bit processors (In development, not complete).
4265 p16f627 p16f628 p16f84 p16f873 p16f877?
4267 \labelwidthstring 00.00.0000
4273 Generate code for the Toshiba TLCS-900H
4274 \begin_inset LatexCommand \index{TLCS-900H}
4278 processor (In development, not complete).
4280 \labelwidthstring 00.00.0000
4285 \begin_inset LatexCommand \index{-mxa51}
4291 Generate code for the Philips XA51
4292 \begin_inset LatexCommand \index{XA51}
4296 processor (In development, not complete).
4297 \layout Subsubsection
4299 Preprocessor Options
4300 \begin_inset LatexCommand \index{Options preprocessor}
4305 \begin_inset LatexCommand \index{Preprocessor options}
4311 \labelwidthstring 00.00.0000
4316 \begin_inset LatexCommand \index{-I<path>}
4322 The additional location where the pre processor will look for <..h> or
4323 \begin_inset Quotes eld
4327 \begin_inset Quotes erd
4332 \labelwidthstring 00.00.0000
4337 \begin_inset LatexCommand \index{-D<macro[=value]>}
4343 Command line definition of macros.
4344 Passed to the pre processor.
4346 \labelwidthstring 00.00.0000
4351 \begin_inset LatexCommand \index{-M}
4357 Tell the preprocessor to output a rule suitable for make describing the
4358 dependencies of each object file.
4359 For each source file, the preprocessor outputs one make-rule whose target
4360 is the object file name for that source file and whose dependencies are
4361 all the files `#include'd in it.
4362 This rule may be a single line or may be continued with `
4364 '-newline if it is long.
4365 The list of rules is printed on standard output instead of the preprocessed
4369 \labelwidthstring 00.00.0000
4374 \begin_inset LatexCommand \index{-C}
4380 Tell the preprocessor not to discard comments.
4381 Used with the `-E' option.
4383 \labelwidthstring 00.00.0000
4388 \begin_inset LatexCommand \index{-MM}
4399 Like `-M' but the output mentions only the user header files included with
4401 \begin_inset Quotes eld
4405 System header files included with `#include <file>' are omitted.
4407 \labelwidthstring 00.00.0000
4412 \begin_inset LatexCommand \index{-Aquestion(answer)}
4418 Assert the answer answer for question, in case it is tested with a preprocessor
4419 conditional such as `#if #question(answer)'.
4420 `-A-' disables the standard assertions that normally describe the target
4423 \labelwidthstring 00.00.0000
4429 (answer) Assert the answer answer for question, in case it is tested with
4430 a preprocessor conditional such as `#if #question(answer)'.
4431 `-A-' disables the standard assertions that normally describe the target
4434 \labelwidthstring 00.00.0000
4439 \begin_inset LatexCommand \index{-Umacro}
4445 Undefine macro macro.
4446 `-U' options are evaluated after all `-D' options, but before any `-include'
4447 and `-imacros' options.
4449 \labelwidthstring 00.00.0000
4454 \begin_inset LatexCommand \index{-dM}
4460 Tell the preprocessor to output only a list of the macro definitions that
4461 are in effect at the end of preprocessing.
4462 Used with the `-E' option.
4464 \labelwidthstring 00.00.0000
4469 \begin_inset LatexCommand \index{-dD}
4475 Tell the preprocessor to pass all macro definitions into the output, in
4476 their proper sequence in the rest of the output.
4478 \labelwidthstring 00.00.0000
4483 \begin_inset LatexCommand \index{-dN}
4494 Like `-dD' except that the macro arguments and contents are omitted.
4495 Only `#define name' is included in the output.
4496 \layout Subsubsection
4499 \begin_inset LatexCommand \index{Options linker}
4504 \begin_inset LatexCommand \index{Linker options}
4510 \labelwidthstring 00.00.0000
4530 \begin_inset LatexCommand \index{-\/-lib-path}
4535 \begin_inset LatexCommand \index{-L -\/-lib-path}
4544 <absolute path to additional libraries> This option is passed to the linkage
4545 editor's additional libraries
4546 \begin_inset LatexCommand \index{Libraries}
4551 The path name must be absolute.
4552 Additional library files may be specified in the command line.
4553 See section Compiling programs for more details.
4555 \labelwidthstring 00.00.0000
4572 \begin_inset LatexCommand \index{-\/-xram-loc}
4576 <Value> The start location of the external ram
4577 \begin_inset LatexCommand \index{xdata}
4581 , default value is 0.
4582 The value entered can be in Hexadecimal or Decimal format, e.g.: -
4592 -xram-loc 0x8000 or -
4604 \labelwidthstring 00.00.0000
4621 \begin_inset LatexCommand \index{-\/-code-loc}
4625 <Value> The start location of the code
4626 \begin_inset LatexCommand \index{code}
4630 segment, default value 0.
4631 Note when this option is used the interrupt vector table is also relocated
4632 to the given address.
4633 The value entered can be in Hexadecimal or Decimal format, e.g.: -
4643 -code-loc 0x8000 or -
4655 \labelwidthstring 00.00.0000
4672 \begin_inset LatexCommand \index{-\/-stack-loc}
4676 <Value> By default the stack
4677 \begin_inset LatexCommand \index{stack}
4681 is placed after the data segment.
4682 Using this option the stack can be placed anywhere in the internal memory
4684 The value entered can be in Hexadecimal or Decimal format, e.g.
4695 -stack-loc 0x20 or -
4706 Since the sp register is incremented before a push or call, the initial
4707 sp will be set to one byte prior the provided value.
4708 The provided value should not overlap any other memory areas such as used
4709 register banks or the data segment and with enough space for the current
4712 \labelwidthstring 00.00.0000
4729 \begin_inset LatexCommand \index{-\/-data-loc}
4733 <Value> The start location of the internal ram data
4734 \begin_inset LatexCommand \index{data}
4739 The value entered can be in Hexadecimal or Decimal format, eg.
4761 (By default, the start location of the internal ram data segment is set
4762 as low as possible in memory, taking into account the used register banks
4763 and the bit segment at address 0x20.
4764 For example if register banks 0 and 1 are used without bit variables, the
4765 data segment will be set, if -
4775 -data-loc is not used, to location 0x10.)
4777 \labelwidthstring 00.00.0000
4794 \begin_inset LatexCommand \index{-\/-idata-loc}
4798 <Value> The start location of the indirectly addressable internal ram
4799 \begin_inset LatexCommand \index{idata}
4803 , default value is 0x80.
4804 The value entered can be in Hexadecimal or Decimal format, eg.
4815 -idata-loc 0x88 or -
4827 \labelwidthstring 00.00.0000
4842 \begin_inset LatexCommand \index{-\/-out-fmt-ihx}
4851 The linker output (final object code) is in Intel Hex format.
4852 \begin_inset LatexCommand \index{Intel hex format}
4856 (This is the default option).
4858 \labelwidthstring 00.00.0000
4873 \begin_inset LatexCommand \index{-\/-out-fmt-s19}
4882 The linker output (final object code) is in Motorola S19 format
4883 \begin_inset LatexCommand \index{Motorola S19 format}
4888 \layout Subsubsection
4891 \begin_inset LatexCommand \index{Options MCS51}
4896 \begin_inset LatexCommand \index{MCS51 options}
4902 \labelwidthstring 00.00.0000
4917 \begin_inset LatexCommand \index{-\/-model-large}
4923 Generate code for Large model programs see section Memory Models for more
4925 If this option is used all source files in the project should be compiled
4927 In addition the standard library routines are compiled with small model,
4928 they will need to be recompiled.
4930 \labelwidthstring 00.00.0000
4945 \begin_inset LatexCommand \index{-\/-model-small}
4956 Generate code for Small Model programs see section Memory Models for more
4958 This is the default model.
4959 \layout Subsubsection
4962 \begin_inset LatexCommand \index{Options DS390}
4967 \begin_inset LatexCommand \index{DS390 options}
4973 \labelwidthstring 00.00.0000
4990 \begin_inset LatexCommand \index{-\/-model-flat24}
5000 Generate 24-bit flat mode code.
5001 This is the one and only that the ds390 code generator supports right now
5002 and is default when using
5007 See section Memory Models for more details.
5009 \labelwidthstring 00.00.0000
5026 \begin_inset LatexCommand \index{-\/-stack-10bit}
5030 Generate code for the 10 bit stack mode of the Dallas DS80C390 part.
5031 This is the one and only that the ds390 code generator supports right now
5032 and is default when using
5037 In this mode, the stack is located in the lower 1K of the internal RAM,
5038 which is mapped to 0x400000.
5039 Note that the support is incomplete, since it still uses a single byte
5040 as the stack pointer.
5041 This means that only the lower 256 bytes of the potential 1K stack space
5042 will actually be used.
5043 However, this does allow you to reclaim the precious 256 bytes of low RAM
5044 for use for the DATA and IDATA segments.
5045 The compiler will not generate any code to put the processor into 10 bit
5047 It is important to ensure that the processor is in this mode before calling
5048 any re-entrant functions compiled with this option.
5049 In principle, this should work with the
5062 \begin_inset LatexCommand \index{-\/-stack-auto}
5068 option, but that has not been tested.
5069 It is incompatible with the
5082 \begin_inset LatexCommand \index{-\/-xstack}
5089 It also only makes sense if the processor is in 24 bit contiguous addressing
5102 -model-flat24 option
5105 \layout Subsubsection
5107 Optimization Options
5108 \begin_inset LatexCommand \index{Options optimization}
5113 \begin_inset LatexCommand \index{Optimization options}
5119 \labelwidthstring 00.00.0000
5134 \begin_inset LatexCommand \index{-\/-nogcse}
5140 Will not do global subexpression elimination, this option may be used when
5141 the compiler creates undesirably large stack/data spaces to store compiler
5143 A warning message will be generated when this happens and the compiler
5144 will indicate the number of extra bytes it allocated.
5145 It recommended that this option NOT be used, #pragma\SpecialChar ~
5147 \begin_inset LatexCommand \index{\#pragma NOGCSE}
5151 can be used to turn off global subexpression elimination
5152 \begin_inset LatexCommand \index{Subexpression elimination}
5156 for a given function only.
5158 \labelwidthstring 00.00.0000
5173 \begin_inset LatexCommand \index{-\/-noinvariant}
5179 Will not do loop invariant optimizations, this may be turned off for reasons
5180 explained for the previous option.
5181 For more details of loop optimizations performed see section Loop Invariants.It
5182 recommended that this option NOT be used, #pragma\SpecialChar ~
5184 \begin_inset LatexCommand \index{\#pragma NOINVARIANT}
5188 can be used to turn off invariant optimizations for a given function only.
5190 \labelwidthstring 00.00.0000
5205 \begin_inset LatexCommand \index{-\/-noinduction}
5211 Will not do loop induction optimizations, see section strength reduction
5212 for more details.It is recommended that this option is NOT used, #pragma\SpecialChar ~
5215 \begin_inset LatexCommand \index{\#pragma NOINDUCTION}
5219 can be used to turn off induction optimizations for a given function only.
5221 \labelwidthstring 00.00.0000
5236 \begin_inset LatexCommand \index{-\/-nojtbound}
5247 Will not generate boundary condition check when switch statements
5248 \begin_inset LatexCommand \index{switch statement}
5252 are implemented using jump-tables.
5253 See section Switch Statements for more details.
5254 It is recommended that this option is NOT used, #pragma\SpecialChar ~
5256 \begin_inset LatexCommand \index{\#pragma NOJTBOUND}
5260 can be used to turn off boundary checking for jump tables for a given function
5263 \labelwidthstring 00.00.0000
5278 \begin_inset LatexCommand \index{-\/-noloopreverse}
5287 Will not do loop reversal
5288 \begin_inset LatexCommand \index{Loop reversing}
5294 \labelwidthstring 00.00.0000
5311 \begin_inset LatexCommand \index{-\/-nolabelopt }
5315 Will not optimize labels (makes the dumpfiles more readable).
5317 \labelwidthstring 00.00.0000
5332 \begin_inset LatexCommand \index{-\/-no-xinit-opt}
5338 Will not memcpy initialized data in far space from code space.
5339 This saves a few bytes in code space if you don't have initialized data.
5340 \layout Subsubsection
5343 \begin_inset LatexCommand \index{Options other}
5349 \labelwidthstring 00.00.0000
5365 \begin_inset LatexCommand \index{-\/-compile-only}
5370 \begin_inset LatexCommand \index{-c -\/-compile-only}
5376 will compile and assemble the source, but will not call the linkage editor.
5378 \labelwidthstring 00.00.0000
5397 \begin_inset LatexCommand \index{-\/-c1mode}
5403 reads the preprocessed source from standard input and compiles it.
5404 The file name for the assembler output must be specified using the -o option.
5406 \labelwidthstring 00.00.0000
5411 \begin_inset LatexCommand \index{-E}
5417 Run only the C preprocessor.
5418 Preprocess all the C source files specified and output the results to standard
5421 \labelwidthstring 00.00.0000
5427 \begin_inset LatexCommand \index{-o <path/file>}
5433 The output path resp.
5434 file where everything will be placed.
5435 If the parameter is a path, it must have a trailing slash (or backslash
5436 for the Windows binaries) to be recognized as a path.
5439 \labelwidthstring 00.00.0000
5454 \begin_inset LatexCommand \index{-\/-stack-auto}
5465 All functions in the source file will be compiled as
5470 \begin_inset LatexCommand \index{reentrant}
5475 the parameters and local variables will be allocated on the stack
5476 \begin_inset LatexCommand \index{stack}
5481 see section Parameters and Local Variables for more details.
5482 If this option is used all source files in the project should be compiled
5486 \labelwidthstring 00.00.0000
5501 \begin_inset LatexCommand \index{-\/-xstack}
5507 Uses a pseudo stack in the first 256 bytes in the external ram for allocating
5508 variables and passing parameters.
5509 See section on external stack for more details.
5511 \labelwidthstring 00.00.0000
5526 \begin_inset LatexCommand \index{-\/-callee-saves}
5531 \begin_inset LatexCommand \index{function prologue}
5535 function1[,function2][,function3]....
5538 The compiler by default uses a caller saves convention for register saving
5539 across function calls, however this can cause unneccessary register pushing
5540 & popping when calling small functions from larger functions.
5541 This option can be used to switch the register saving convention for the
5542 function names specified.
5543 The compiler will not save registers when calling these functions, no extra
5544 code will be generated at the entry & exit for these functions to save
5545 & restore the registers used by these functions, this can SUBSTANTIALLY
5546 reduce code & improve run time performance of the generated code.
5547 In the future the compiler (with interprocedural analysis) will be able
5548 to determine the appropriate scheme to use for each function call.
5549 DO NOT use this option for built-in functions such as _mulint..., if this
5550 option is used for a library function the appropriate library function
5551 needs to be recompiled with the same option.
5552 If the project consists of multiple source files then all the source file
5553 should be compiled with the same -
5563 -callee-saves option string.
5564 Also see #pragma\SpecialChar ~
5566 \begin_inset LatexCommand \index{\#pragma CALLEE-SAVES}
5572 \labelwidthstring 00.00.0000
5587 \begin_inset LatexCommand \index{-\/-debug}
5596 When this option is used the compiler will generate debug information, that
5597 can be used with the SDCDB.
5598 The debug information is collected in a file with .cdb extension.
5599 For more information see documentation for SDCDB.
5601 \labelwidthstring 00.00.0000
5618 \begin_inset LatexCommand \index{-\/-peep-file}
5622 <filename> This option can be used to use additional rules to be used by
5623 the peep hole optimizer.
5624 See section Peep Hole optimizations for details on how to write these rules.
5626 \labelwidthstring 00.00.0000
5631 \begin_inset LatexCommand \index{-S}
5642 Stop after the stage of compilation proper; do not assemble.
5643 The output is an assembler code file for the input file specified.
5645 \labelwidthstring 00.00.0000
5649 -Wa_asmOption[,asmOption]
5652 \begin_inset LatexCommand \index{-Wa\_asmOption[,asmOption]}
5657 Pass the asmOption to the assembler.
5659 \labelwidthstring 00.00.0000
5663 -Wl_linkOption[,linkOption]
5666 \begin_inset LatexCommand \index{-Wl\_linkOption[,linkOption]}
5671 Pass the linkOption to the linker.
5673 \labelwidthstring 00.00.0000
5688 \begin_inset LatexCommand \index{-\/-int-long-reent}
5694 Integer (16 bit) and long (32 bit) libraries have been compiled as reentrant.
5695 Note by default these libraries are compiled as non-reentrant.
5696 See section Installation for more details.
5698 \labelwidthstring 00.00.0000
5713 \begin_inset LatexCommand \index{-\/-cyclomatic}
5722 This option will cause the compiler to generate an information message for
5723 each function in the source file.
5724 The message contains some
5728 information about the function.
5729 The number of edges and nodes the compiler detected in the control flow
5730 graph of the function, and most importantly the
5732 cyclomatic complexity
5733 \begin_inset LatexCommand \index{Cyclomatic complexity}
5739 see section on Cyclomatic Complexity for more details.
5741 \labelwidthstring 00.00.0000
5756 \begin_inset LatexCommand \index{-\/-float-reent}
5765 Floating point library is compiled as reentrant
5766 \begin_inset LatexCommand \index{reentrant}
5770 .See section Installation for more details.
5772 \labelwidthstring 00.00.0000
5787 \begin_inset LatexCommand \index{-\/-nooverlay}
5793 The compiler will not overlay parameters and local variables of any function,
5794 see section Parameters and local variables for more details.
5796 \labelwidthstring 00.00.0000
5811 \begin_inset LatexCommand \index{-\/-main-return}
5817 This option can be used when the code generated is called by a monitor
5819 The compiler will generate a 'ret' upon return from the 'main'
5820 \begin_inset LatexCommand \index{main return}
5825 The default option is to lock up i.e.
5828 \labelwidthstring 00.00.0000
5843 \begin_inset LatexCommand \index{-\/-no-peep}
5849 Disable peep-hole optimization.
5851 \labelwidthstring 00.00.0000
5866 \begin_inset LatexCommand \index{-\/-peep-asm}
5872 Pass the inline assembler code through the peep hole optimizer.
5873 This can cause unexpected changes to inline assembler code, please go through
5874 the peephole optimizer
5875 \begin_inset LatexCommand \index{Peephole optimizer}
5879 rules defined in the source file tree '<target>/peeph.def' before using
5882 \labelwidthstring 00.00.0000
5899 \begin_inset LatexCommand \index{-\/-iram-size<Value>}
5903 Causes the linker to check if the internal ram usage is within limits of
5906 \labelwidthstring 00.00.0000
5923 \begin_inset LatexCommand \index{-\/-xram-size<Value>}
5927 Causes the linker to check if the external ram usage is within limits of
5930 \labelwidthstring 00.00.0000
5947 \begin_inset LatexCommand \index{-\/-code-size<Value>}
5951 Causes the linker to check if the code usage is within limits of the given
5954 \labelwidthstring 00.00.0000
5969 \begin_inset LatexCommand \index{-\/-nostdincl}
5975 This will prevent the compiler from passing on the default include path
5976 to the preprocessor.
5978 \labelwidthstring 00.00.0000
5993 \begin_inset LatexCommand \index{-\/-nostdlib}
5999 This will prevent the compiler from passing on the default library
6000 \begin_inset LatexCommand \index{Libraries}
6006 \labelwidthstring 00.00.0000
6021 \begin_inset LatexCommand \index{-\/-verbose}
6027 Shows the various actions the compiler is performing.
6029 \labelwidthstring 00.00.0000
6034 \begin_inset LatexCommand \index{-V}
6040 Shows the actual commands the compiler is executing.
6042 \labelwidthstring 00.00.0000
6057 \begin_inset LatexCommand \index{-\/-no-c-code-in-asm}
6063 Hides your ugly and inefficient c-code from the asm file, so you can always
6064 blame the compiler :).
6066 \labelwidthstring 00.00.0000
6081 \begin_inset LatexCommand \index{-\/-i-code-in-asm}
6087 Include i-codes in the asm file.
6088 Sounds like noise but is most helpfull for debugging the compiler itself.
6090 \labelwidthstring 00.00.0000
6105 \begin_inset LatexCommand \index{-\/-less-pedantic}
6111 Disable some of the more pedantic warnings (jwk burps: please be more specific
6114 \labelwidthstring 00.00.0000
6129 \begin_inset LatexCommand \index{-\/-print-search-dirs}
6135 Display the directories in the compiler's search path
6136 \layout Subsubsection
6138 Intermediate Dump Options
6139 \begin_inset LatexCommand \index{Options intermediate dump}
6144 \begin_inset LatexCommand \index{Intermediate dump options}
6151 The following options are provided for the purpose of retargetting and debugging
6153 These provided a means to dump the intermediate code (iCode
6154 \begin_inset LatexCommand \index{iCode}
6158 ) generated by the compiler in human readable form at various stages of
6159 the compilation process.
6162 \labelwidthstring 00.00.0000
6177 \begin_inset LatexCommand \index{-\/-dumpraw}
6183 This option will cause the compiler to dump the intermediate code into
6186 <source filename>.dumpraw
6188 just after the intermediate code has been generated for a function, i.e.
6189 before any optimizations are done.
6191 \begin_inset LatexCommand \index{Basic blocks}
6195 at this stage ordered in the depth first number, so they may not be in
6196 sequence of execution.
6198 \labelwidthstring 00.00.0000
6213 \begin_inset LatexCommand \index{-\/-dumpgcse}
6219 Will create a dump of iCode's, after global subexpression elimination
6220 \begin_inset LatexCommand \index{Global subexpression elimination}
6226 <source filename>.dumpgcse.
6228 \labelwidthstring 00.00.0000
6243 \begin_inset LatexCommand \index{-\/-dumpdeadcode}
6249 Will create a dump of iCode's, after deadcode elimination
6250 \begin_inset LatexCommand \index{Dead-code elimination}
6256 <source filename>.dumpdeadcode.
6258 \labelwidthstring 00.00.0000
6273 \begin_inset LatexCommand \index{-\/-dumploop}
6282 Will create a dump of iCode's, after loop optimizations
6283 \begin_inset LatexCommand \index{Loop optimization}
6289 <source filename>.dumploop.
6291 \labelwidthstring 00.00.0000
6306 \begin_inset LatexCommand \index{-\/-dumprange}
6315 Will create a dump of iCode's, after live range analysis
6316 \begin_inset LatexCommand \index{Live range analysis}
6322 <source filename>.dumprange.
6324 \labelwidthstring 00.00.0000
6339 \begin_inset LatexCommand \index{-\/-dumlrange}
6345 Will dump the life ranges
6346 \begin_inset LatexCommand \index{Live range analysis}
6352 \labelwidthstring 00.00.0000
6367 \begin_inset LatexCommand \index{-\/-dumpregassign}
6376 Will create a dump of iCode's, after register assignment
6377 \begin_inset LatexCommand \index{Register assignment}
6383 <source filename>.dumprassgn.
6385 \labelwidthstring 00.00.0000
6400 \begin_inset LatexCommand \index{-\/-dumplrange}
6406 Will create a dump of the live ranges of iTemp's
6408 \labelwidthstring 00.00.0000
6423 \begin_inset LatexCommand \index{-\/-dumpall}
6434 Will cause all the above mentioned dumps to be created.
6437 Environment variables
6438 \begin_inset LatexCommand \index{Environment variables}
6445 SDCC recognizes the following environment variables:
6447 \labelwidthstring 00.00.0000
6452 \begin_inset LatexCommand \index{SDCC\_LEAVE\_SIGNALS}
6458 SDCC installs a signal handler
6459 \begin_inset LatexCommand \index{signal handler}
6463 to be able to delete temporary files after an user break (^C) or an exception.
6464 If this environment variable is set, SDCC won't install the signal handler
6465 in order to be able to debug SDCC.
6467 \labelwidthstring 00.00.0000
6472 \begin_inset LatexCommand \index{TMP}
6478 \begin_inset LatexCommand \index{TEMP}
6484 \begin_inset LatexCommand \index{TMPDIR}
6490 Path, where temporary files will be created.
6491 The order of the variables is the search order.
6492 In a standard *nix environment these variables are not set, and there's
6493 no need to set them.
6494 On Windows it's recommended to set one of them.
6496 \labelwidthstring 00.00.0000
6501 \begin_inset LatexCommand \index{SDCC\_HOME}
6508 \begin_inset Quotes sld
6511 2.3 Install and search paths
6512 \begin_inset Quotes srd
6517 \labelwidthstring 00.00.0000
6522 \begin_inset LatexCommand \index{SDCC\_INCLUDE}
6529 \begin_inset Quotes sld
6532 2.3 Install and search paths
6533 \begin_inset Quotes srd
6538 \labelwidthstring 00.00.0000
6543 \begin_inset LatexCommand \index{SDCC\_LIB}
6550 \begin_inset Quotes sld
6553 2.3 Install and search paths
6554 \begin_inset Quotes srd
6560 There are some more environment variables recognized by SDCC, but these
6561 are solely used for debugging purposes.
6562 They can change or disappear very quickly, and will never be documentated.
6565 MCS51/DS390 Storage Class
6566 \begin_inset LatexCommand \index{Storage class}
6573 In addition to the ANSI storage classes SDCC allows the following MCS51
6574 specific storage classes.
6575 \layout Subsubsection
6578 \begin_inset LatexCommand \index{xdata}
6585 Variables declared with this storage class will be placed in the extern
6591 storage class for Large Memory model, e.g.:
6597 xdata unsigned char xduc;
6598 \layout Subsubsection
6601 \begin_inset LatexCommand \index{data}
6612 storage class for Small Memory model.
6613 Variables declared with this storage class will be allocated in the internal
6620 \layout Subsubsection
6623 \begin_inset LatexCommand \index{idata}
6630 Variables declared with this storage class will be allocated into the indirectly
6631 addressable portion of the internal ram of a 8051, e.g.:
6637 \layout Subsubsection
6640 \begin_inset LatexCommand \index{bit}
6647 This is a data-type and a storage class specifier.
6648 When a variable is declared as a bit, it is allocated into the bit addressable
6649 memory of 8051, e.g.:
6655 \layout Subsubsection
6658 \begin_inset LatexCommand \index{sfr}
6663 \begin_inset LatexCommand \index{sbit}
6670 Like the bit keyword,
6674 signifies both a data-type and storage class, they are used to describe
6675 the special function registers and special bit variables of a 8051, eg:
6680 sfr at 0x80 P0; /* special function register P0 at location 0x80 */
6682 sbit at 0xd7 CY; /* CY (Carry Flag
6683 \begin_inset LatexCommand \index{Flags}
6688 \begin_inset LatexCommand \index{Carry flag}
6696 \begin_inset LatexCommand \index{Pointers}
6703 SDCC allows (via language extensions) pointers to explicitly point to any
6704 of the memory spaces
6705 \begin_inset LatexCommand \index{Memory model}
6710 In addition to the explicit pointers, the compiler uses (by default) generic
6711 pointers which can be used to point to any of the memory spaces.
6715 Pointer declaration examples:
6720 /* pointer physically in xternal ram pointing to object in internal ram
6723 data unsigned char * xdata p;
6727 /* pointer physically in code rom pointing to data in xdata space */
6729 xdata unsigned char * code p;
6733 /* pointer physically in code space pointing to data in code space */
6735 code unsigned char * code p;
6739 /* the folowing is a generic pointer physically located in xdata space */
6744 Well you get the idea.
6749 All unqualified pointers are treated as 3-byte (4-byte for the ds390)
6762 The highest order byte of the
6766 pointers contains the data space information.
6767 Assembler support routines are called whenever data is stored or retrieved
6773 These are useful for developing reusable library
6774 \begin_inset LatexCommand \index{Libraries}
6779 Explicitly specifying the pointer type will generate the most efficient
6784 \begin_inset LatexCommand \index{Parameters}
6789 \begin_inset LatexCommand \index{Local variable}
6796 Automatic (local) variables and parameters to functions can either be placed
6797 on the stack or in data-space.
6798 The default action of the compiler is to place these variables in the internal
6799 RAM (for small model) or external RAM (for large model).
6800 This in fact makes them
6803 \begin_inset LatexCommand \index{static}
6809 so by default functions are non-reentrant
6810 \begin_inset LatexCommand \index{reentrant}
6818 They can be placed on the stack
6819 \begin_inset LatexCommand \index{stack}
6836 \begin_inset LatexCommand \index{-\/-stack-auto}
6842 option or by using the
6845 \begin_inset LatexCommand \index{reentrant}
6851 keyword in the function declaration, e.g.:
6856 unsigned char foo(char i) reentrant
6866 Since stack space on 8051 is limited, the
6884 option should be used sparingly.
6885 Note that the reentrant keyword just means that the parameters & local
6886 variables will be allocated to the stack, it
6890 mean that the function is register bank independent.
6894 Local variables can be assigned storage classes and absolute
6895 \begin_inset LatexCommand \index{Absolute addressing}
6904 unsigned char foo() {
6910 xdata unsigned char i;
6922 data at 0x31 unsiged char j;
6934 In the above example the variable
6938 will be allocated in the external ram,
6942 in bit addressable space and
6961 or when a function is declared as
6965 this should only be done for static variables.
6968 Parameters however are not allowed any storage class, (storage classes for
6969 parameters will be ignored), their allocation is governed by the memory
6970 model in use, and the reentrancy options.
6974 \begin_inset LatexCommand \index{Overlaying}
6982 \begin_inset LatexCommand \index{reentrant}
6986 functions SDCC will try to reduce internal ram space usage by overlaying
6987 parameters and local variables of a function (if possible).
6988 Parameters and local variables of a function will be allocated to an overlayabl
6989 e segment if the function has
6991 no other function calls and the function is non-reentrant and the memory
6993 \begin_inset LatexCommand \index{Memory model}
7000 If an explicit storage class
7001 \begin_inset LatexCommand \index{Storage class}
7005 is specified for a local variable, it will NOT be overlayed.
7008 Note that the compiler (not the linkage editor) makes the decision for overlayin
7010 Functions that are called from an interrupt service routine should be preceded
7011 by a #pragma\SpecialChar ~
7013 \begin_inset LatexCommand \index{\#pragma NOOVERLAY}
7017 if they are not reentrant.
7020 Also note that the compiler does not do any processing of inline
7021 \begin_inset LatexCommand \index{inline}
7025 assembler code, so the compiler might incorrectly assign local variables
7026 and parameters of a function into the overlay segment if the inline assembler
7027 code calls other c-functions that might use the overlay.
7028 In that case the #pragma\SpecialChar ~
7029 NOOVERLAY should be used.
7032 Parameters and Local variables of functions that contain 16 or 32 bit multiplica
7034 \begin_inset LatexCommand \index{Multiplication}
7039 \begin_inset LatexCommand \index{Division}
7043 will NOT be overlayed since these are implemented using external functions,
7052 \begin_inset LatexCommand \index{\#pragma NOOVERLAY}
7058 void set_error(unsigned char errcd)
7074 void some_isr () interrupt
7075 \begin_inset LatexCommand \index{interrupt}
7080 \begin_inset LatexCommand \index{using}
7110 In the above example the parameter
7118 would be assigned to the overlayable segment if the #pragma\SpecialChar ~
7120 not present, this could cause unpredictable runtime behavior when called
7122 The #pragma\SpecialChar ~
7123 NOOVERLAY ensures that the parameters and local variables for
7124 the function are NOT overlayed.
7127 Interrupt Service Routines
7130 SDCC allows interrupt service routines to be coded in C, with some extended
7136 void timer_isr (void) interrupt 2 using 1
7146 The number following the
7149 \begin_inset LatexCommand \index{interrupt}
7155 keyword is the interrupt number this routine will service.
7156 The compiler will insert a call to this routine in the interrupt vector
7157 table for the interrupt number specified.
7162 keyword is used to tell the compiler to use the specified register bank
7163 (8051 specific) when generating code for this function.
7164 Note that when some function is called from an interrupt service routine
7165 it should be preceded by a #pragma\SpecialChar ~
7167 \begin_inset LatexCommand \index{\#pragma NOOVERLAY}
7171 if it is not reentrant.
7172 A special note here, int (16 bit) and long (32 bit) integer division
7173 \begin_inset LatexCommand \index{Division}
7178 \begin_inset LatexCommand \index{Multiplication}
7183 \begin_inset LatexCommand \index{Modulus}
7187 operations are implemented using external support routines developed in
7188 ANSI-C, if an interrupt service routine needs to do any of these operations
7189 then the support routines (as mentioned in a following section) will have
7190 to be recompiled using the
7203 \begin_inset LatexCommand \index{-\/-stack-auto}
7209 option and the source file will need to be compiled using the
7224 \begin_inset LatexCommand \index{-\/-int-long-rent}
7231 If you have multiple source files in your project, interrupt service routines
7232 can be present in any of them, but a prototype of the isr MUST be present
7233 or included in the file that contains the function
7240 Interrupt Numbers and the corresponding address & descriptions for the Standard
7241 8051 are listed below.
7242 SDCC will automatically adjust the interrupt vector table to the maximum
7243 interrupt number specified.
7249 \begin_inset Tabular
7250 <lyxtabular version="3" rows="6" columns="3">
7252 <column alignment="block" valignment="top" leftline="true" width="0in">
7253 <column alignment="block" valignment="top" leftline="true" width="0in">
7254 <column alignment="block" valignment="top" leftline="true" rightline="true" width="0in">
7255 <row topline="true" bottomline="true">
7256 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
7264 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
7272 <cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
7281 <row topline="true">
7282 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
7290 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
7298 <cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
7307 <row topline="true">
7308 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
7316 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
7324 <cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
7333 <row topline="true">
7334 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
7342 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
7350 <cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
7359 <row topline="true">
7360 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
7368 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
7376 <cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
7385 <row topline="true" bottomline="true">
7386 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
7394 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
7402 <cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
7419 If the interrupt service routine is defined without
7422 \begin_inset LatexCommand \index{using}
7428 a register bank or with register bank 0 (using 0), the compiler will save
7429 the registers used by itself on the stack upon entry and restore them at
7430 exit, however if such an interrupt service routine calls another function
7431 then the entire register bank will be saved on the stack.
7432 This scheme may be advantageous for small interrupt service routines which
7433 have low register usage.
7436 If the interrupt service routine is defined to be using a specific register
7441 are save and restored, if such an interrupt service routine calls another
7442 function (using another register bank) then the entire register bank of
7443 the called function will be saved on the stack.
7444 This scheme is recommended for larger interrupt service routines.
7447 Calling other functions from an interrupt service routine is not recommended,
7448 avoid it if possible.
7452 Also see the _naked modifier.
7460 <TODO: this isn't implemented at all!>
7466 A special keyword may be associated with a function declaring it as
7471 SDCC will generate code to disable all interrupts upon entry to a critical
7472 function and enable them back before returning.
7473 Note that nesting critical functions may cause unpredictable results.
7491 The critical attribute maybe used with other attributes like
7497 \begin_inset LatexCommand \index{Naked functions}
7504 A special keyword may be associated with a function declaring it as
7507 \begin_inset LatexCommand \index{\_naked}
7518 function modifier attribute prevents the compiler from generating prologue
7519 \begin_inset LatexCommand \index{function prologue}
7524 \begin_inset LatexCommand \index{function epilogue}
7528 code for that function.
7529 This means that the user is entirely responsible for such things as saving
7530 any registers that may need to be preserved, selecting the proper register
7531 bank, generating the
7535 instruction at the end, etc.
7536 Practically, this means that the contents of the function must be written
7537 in inline assembler.
7538 This is particularly useful for interrupt functions, which can have a large
7539 (and often unnecessary) prologue/epilogue.
7540 For example, compare the code generated by these two functions:
7545 data unsigned char counter;
7547 void simpleInterrupt(void) interrupt
7548 \begin_inset LatexCommand \index{interrupt}
7566 void nakedInterrupt(void) interrupt 2 _naked
7575 \begin_inset LatexCommand \index{\_asm}
7604 ; MUST explicitly include ret in _naked function.
7611 \begin_inset LatexCommand \index{\_endasm}
7620 For an 8051 target, the generated simpleInterrupt looks like:
7761 whereas nakedInterrupt looks like:
7785 ; MUST explicitly include ret(i) in _naked function.
7788 While there is nothing preventing you from writing C code inside a _naked
7789 function, there are many ways to shoot yourself in the foot doing this,
7790 and it is recommended that you stick to inline assembler.
7793 Functions using private banks
7794 \begin_inset LatexCommand \index{bank}
7804 \begin_inset LatexCommand \index{using}
7810 attribute (which tells the compiler to use a register bank other than the
7811 default bank zero) should only be applied to
7814 \begin_inset LatexCommand \index{interrupt}
7820 functions (see note 1 below).
7821 This will in most circumstances make the generated ISR code more efficient
7822 since it will not have to save registers on the stack.
7829 attribute will have no effect on the generated code for a
7833 function (but may occasionally be useful anyway
7839 possible exception: if a function is called ONLY from 'interrupt' functions
7840 using a particular bank, it can be declared with the same 'using' attribute
7841 as the calling 'interrupt' functions.
7842 For instance, if you have several ISRs using bank one, and all of them
7843 call memcpy(), it might make sense to create a specialized version of memcpy()
7844 'using 1', since this would prevent the ISR from having to save bank zero
7845 to the stack on entry and switch to bank zero before calling the function
7852 (pending: I don't think this has been done yet)
7859 function using a non-zero bank will assume that it can trash that register
7860 bank, and will not save it.
7861 Since high-priority interrupts
7862 \begin_inset LatexCommand \index{interrupt priority}
7866 can interrupt low-priority ones on the 8051 and friends, this means that
7867 if a high-priority ISR
7871 a particular bank occurs while processing a low-priority ISR
7875 the same bank, terrible and bad things can happen.
7876 To prevent this, no single register bank should be
7880 by both a high priority and a low priority ISR.
7881 This is probably most easily done by having all high priority ISRs use
7882 one bank and all low priority ISRs use another.
7883 If you have an ISR which can change priority at runtime, you're on your
7884 own: I suggest using the default bank zero and taking the small performance
7888 It is most efficient if your ISR calls no other functions.
7889 If your ISR must call other functions, it is most efficient if those functions
7890 use the same bank as the ISR (see note 1 below); the next best is if the
7891 called functions use bank zero.
7892 It is very inefficient to call a function using a different, non-zero bank
7898 \begin_inset LatexCommand \index{Absolute addressing}
7905 Data items can be assigned an absolute address with the
7908 \begin_inset LatexCommand \index{at}
7914 keyword, in addition to a storage class, e.g.:
7920 \begin_inset LatexCommand \index{xdata}
7925 \begin_inset LatexCommand \index{at}
7929 0x8000 unsigned char PORTA_8255 ;
7932 In the above example the PORTA_8255 will be allocated to the location 0x8000
7933 of the external ram.
7934 Note that this feature is provided to give the programmer access to
7938 devices attached to the controller.
7939 The compiler does not actually reserve any space for variables declared
7940 in this way (they are implemented with an equate in the assembler).
7941 Thus it is left to the programmer to make sure there are no overlaps with
7942 other variables that are declared without the absolute address.
7943 The assembler listing file (.lst
7944 \begin_inset LatexCommand \index{.lst}
7948 ) and the linker output files (.rst
7949 \begin_inset LatexCommand \index{.rst}
7954 \begin_inset LatexCommand \index{.map}
7958 ) are a good places to look for such overlaps.
7962 Absolute address can be specified for variables in all storage classes,
7969 \begin_inset LatexCommand \index{bit}
7974 \begin_inset LatexCommand \index{at}
7981 The above example will allocate the variable at offset 0x02 in the bit-addressab
7983 There is no real advantage to assigning absolute addresses to variables
7984 in this manner, unless you want strict control over all the variables allocated.
7985 One possible use would be to write hardware portable code.
7986 For example, if you have a routine that uses one or more of the microcontroller
7987 I/O pins, and such pins are different for two different hardwares, you
7988 can declare the I/O pins in you routine using
8001 void DS1306_put(unsigned char value)
8009 unsigned char mask=0x80;
8033 SDI=(value & mask)?1:0;
8074 Then, someplace in the code for the first hardware you would use
8079 bit at 0x80 SDI;\SpecialChar ~
8083 /*I/O port 0, bit 0*/
8085 bit at 0x81 SCLK;\SpecialChar ~
8088 /*I/O port 0, bit 1*/
8090 bit CPOL;\SpecialChar ~
8101 /*This is a variable, let the linker allocate this one*/
8104 Similarly, for the second hardware you would use
8109 bit at 0x83 SDI;\SpecialChar ~
8113 /*I/O port 0, bit 3*/
8115 bit at 0x91 SCLK;\SpecialChar ~
8118 /*I/O port 1, bit 1*/
8120 bit CPOL;\SpecialChar ~
8131 /*This is a variable, let the linker allocate this one*/
8134 and you can use the same hardware dependant routine without changes, as
8135 for example in a library.
8136 This is somehow similar to sbit, but only one absolute address has to be
8137 specified in the whole project.
8141 \begin_inset LatexCommand \index{Startup code}
8148 The compiler inserts a call to the C routine
8150 _sdcc_external_startup()
8151 \begin_inset LatexCommand \index{\_sdcc\_external\_startup()}
8160 at the start of the CODE area.
8161 This routine is in the runtime library
8162 \begin_inset LatexCommand \index{Runtime library}
8167 By default this routine returns 0, if this routine returns a non-zero value,
8168 the static & global variable initialization will be skipped and the function
8169 main will be invoked Other wise static & global variables will be initialized
8170 before the function main is invoked.
8173 _sdcc_external_startup()
8175 routine to your program to override the default if you need to setup hardware
8176 or perform some other critical operation prior to static & global variable
8180 Inline Assembler Code
8181 \begin_inset LatexCommand \index{Assembler routines}
8188 SDCC allows the use of in-line assembler with a few restriction as regards
8190 All labels defined within inline assembler code
8198 where nnnn is a number less than 100 (which implies a limit of utmost 100
8199 inline assembler labels
8207 It is strongly recommended that each assembly instruction (including labels)
8208 be placed in a separate line (as the example shows).
8222 \begin_inset LatexCommand \index{-\/-peep-asm}
8228 command line option is used, the inline assembler code will be passed through
8229 the peephole optimizer
8230 \begin_inset LatexCommand \index{Peephole optimizer}
8235 This might cause some unexpected changes in the inline assembler code.
8236 Please go throught the peephole optimizer rules defined in file
8240 carefully before using this option.
8246 \begin_inset LatexCommand \index{\_asm}
8276 \begin_inset LatexCommand \index{\_endasm}
8283 The inline assembler code can contain any valid code understood by the assembler
8284 , this includes any assembler directives and comment lines.
8285 The compiler does not do any validation of the code within the
8295 Inline assembler code cannot reference any C-Labels, however it can reference
8297 \begin_inset LatexCommand \index{Labels}
8301 defined by the inline assembler, e.g.:
8326 ; some assembler code
8346 /* some more c code */
8348 clabel:\SpecialChar ~
8350 /* inline assembler cannot reference this label */
8362 $0003: ;label (can be reference by inline assembler only)
8374 /* some more c code */
8379 In other words inline assembly code can access labels defined in inline
8380 assembly within the scope of the funtion.
8381 The same goes the other way, ie.
8382 labels defines in inline assembly CANNOT be accessed by C statements.
8386 \begin_inset LatexCommand \index{int (16 bit)}
8391 \begin_inset LatexCommand \index{long (32 bit)}
8398 For signed & unsigned int (16 bit) and long (32 bit) variables, division,
8399 multiplication and modulus operations are implemented by support routines.
8400 These support routines are all developed in ANSI-C to facilitate porting
8401 to other MCUs, although some model specific assembler optimations are used.
8402 The following files contain the described routine, all of them can be found
8403 in <installdir>/share/sdcc/lib.
8408 \begin_inset Tabular
8409 <lyxtabular version="3" rows="11" columns="2">
8411 <column alignment="center" valignment="top" leftline="true" width="0(null)">
8412 <column alignment="center" valignment="top" leftline="true" rightline="true" width="0(null)">
8413 <row topline="true" bottomline="true">
8414 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
8424 <cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
8435 <row topline="true">
8436 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
8444 <cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
8449 16 bit multiplication
8453 <row topline="true">
8454 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
8462 <cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
8467 signed 16 bit division (calls _divuint)
8471 <row topline="true">
8472 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
8480 <cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
8485 unsigned 16 bit division
8489 <row topline="true">
8490 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
8498 <cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
8503 signed 16 bit modulus (calls _moduint)
8507 <row topline="true">
8508 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
8516 <cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
8521 unsigned 16 bit modulus
8525 <row topline="true">
8526 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
8534 <cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
8539 32 bit multiplication
8543 <row topline="true">
8544 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
8552 <cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
8557 signed 32 division (calls _divulong)
8561 <row topline="true">
8562 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
8570 <cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
8575 unsigned 32 division
8579 <row topline="true">
8580 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
8588 <cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
8593 signed 32 bit modulus (calls _modulong)
8597 <row topline="true" bottomline="true">
8598 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
8606 <cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
8611 unsigned 32 bit modulus
8627 Since they are compiled as
8632 \begin_inset LatexCommand \index{reentrant}
8637 \begin_inset LatexCommand \index{interrupt}
8641 service routines should not do any of the above operations.
8642 If this is unavoidable then the above routines will need to be compiled
8656 \begin_inset LatexCommand \index{-\/-stack-auto}
8662 option, after which the source program will have to be compiled with
8675 \begin_inset LatexCommand \index{-\/-int-long-rent}
8682 Notice that you don't have to call this routines directly.
8683 The compiler will use them automatically every time a integer operation
8687 Floating Point Support
8688 \begin_inset LatexCommand \index{Floating point support}
8695 SDCC supports IEEE (single precision 4bytes) floating point numbers.The floating
8696 point support routines are derived from gcc's floatlib.c and consists of
8697 the following routines:
8704 \begin_inset Tabular
8705 <lyxtabular version="3" rows="17" columns="2">
8707 <column alignment="center" valignment="top" leftline="true" width="0(null)">
8708 <column alignment="center" valignment="top" leftline="true" rightline="true" width="0(null)">
8709 <row topline="true" bottomline="true">
8710 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
8727 <cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
8736 <row topline="true">
8737 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
8754 <cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
8768 add floating point numbers
8772 <row topline="true">
8773 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
8790 <cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
8804 subtract floating point numbers
8808 <row topline="true">
8809 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
8826 <cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
8840 divide floating point numbers
8844 <row topline="true">
8845 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
8862 <cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
8876 multiply floating point numbers
8880 <row topline="true">
8881 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
8898 <cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
8912 convert floating point to unsigned char
8916 <row topline="true">
8917 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
8934 <cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
8948 convert floating point to signed char
8952 <row topline="true">
8953 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
8970 <cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
8984 convert floating point to unsigned int
8988 <row topline="true">
8989 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
9006 <cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
9020 convert floating point to signed int
9024 <row topline="true">
9025 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
9051 <cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
9065 convert floating point to unsigned long
9069 <row topline="true">
9070 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
9087 <cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
9101 convert floating point to signed long
9105 <row topline="true">
9106 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
9123 <cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
9137 convert unsigned char to floating point
9141 <row topline="true">
9142 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
9159 <cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
9173 convert char to floating point number
9177 <row topline="true">
9178 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
9195 <cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
9209 convert unsigned int to floating point
9213 <row topline="true">
9214 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
9231 <cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
9245 convert int to floating point numbers
9249 <row topline="true">
9250 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
9267 <cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
9281 convert unsigned long to floating point number
9285 <row topline="true" bottomline="true">
9286 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
9303 <cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
9317 convert long to floating point number
9331 Note if all these routines are used simultaneously the data space might
9333 For serious floating point usage it is strongly recommended that the large
9335 Also notice that you don't have to call this routines directly.
9336 The compiler will use them automatically every time a floating point operation
9341 \begin_inset LatexCommand \index{Memory model}
9346 \begin_inset LatexCommand \index{MCS51 memory}
9353 SDCC allows two memory models for MCS51 code, small and large.
9354 Modules compiled with different memory models should
9358 be combined together or the results would be unpredictable.
9359 The library routines supplied with the compiler are compiled as both small
9361 The compiled library modules are contained in seperate directories as small
9362 and large so that you can link to either set.
9366 When the large model is used all variables declared without a storage class
9367 will be allocated into the external ram, this includes all parameters and
9368 local variables (for non-reentrant
9369 \begin_inset LatexCommand \index{reentrant}
9374 When the small model is used variables without storage class are allocated
9375 in the internal ram.
9378 Judicious usage of the processor specific storage classes
9379 \begin_inset LatexCommand \index{Storage class}
9383 and the 'reentrant' function type will yield much more efficient code,
9384 than using the large model.
9385 Several optimizations are disabled when the program is compiled using the
9386 large model, it is therefore strongly recommdended that the small model
9387 be used unless absolutely required.
9391 \begin_inset LatexCommand \index{Memory model}
9396 \begin_inset LatexCommand \index{DS390 memory model}
9403 The only model supported is Flat 24
9404 \begin_inset LatexCommand \index{Flat 24 (memory model)}
9409 This generates code for the 24 bit contiguous addressing mode of the Dallas
9411 In this mode, up to four meg of external RAM or code space can be directly
9413 See the data sheets at www.dalsemi.com for further information on this part.
9417 In older versions of the compiler, this option was used with the MCS51 code
9423 Now, however, the '390 has it's own code generator, selected by the
9432 Note that the compiler does not generate any code to place the processor
9433 into 24 bitmode (although
9437 in the ds390 libraries will do that for you).
9443 \begin_inset LatexCommand \index{Tinibios (DS390)}
9447 , the boot loader or similar code must ensure that the processor is in 24
9448 bit contiguous addressing mode before calling the SDCC startup code.
9466 option, variables will by default be placed into the XDATA segment.
9471 Segments may be placed anywhere in the 4 meg address space using the usual
9483 Note that if any segments are located above 64K, the -r flag must be passed
9484 to the linker to generate the proper segment relocations, and the Intel
9485 HEX output format must be used.
9486 The -r flag can be passed to the linker by using the option
9490 on the sdcc command line.
9491 However, currently the linker can not handle code segments > 64k.
9494 Defines Created by the Compiler
9495 \begin_inset LatexCommand \index{Defines created by the compiler}
9502 The compiler creates the following #defines
9503 \begin_inset LatexCommand \index{\#defines}
9511 \begin_inset LatexCommand \index{SDCC}
9515 - this Symbol is always defined.
9519 \begin_inset LatexCommand \index{SDCC\_mcs51}
9524 \begin_inset LatexCommand \index{SDCC\_ds390}
9529 \begin_inset LatexCommand \index{SDCC\_z80}
9533 , etc - depending on the model used (e.g.: -mds390)
9537 \begin_inset LatexCommand \index{\_\_mcs51}
9542 \begin_inset LatexCommand \index{\_\_ds390}
9547 \begin_inset LatexCommand \index{\_\_z80}
9551 , etc - depending on the model used (e.g.
9556 \begin_inset LatexCommand \index{SDCC\_STACK\_AUTO}
9560 - this symbol is defined when
9578 \begin_inset LatexCommand \index{SDCC\_MODEL\_SMALL}
9600 \begin_inset LatexCommand \index{SDCC\_MODEL\_LARGE}
9622 \begin_inset LatexCommand \index{SDCC\_USE\_XSTACK}
9644 \begin_inset LatexCommand \index{SDCC\_STACK\_TENBIT}
9656 \begin_inset LatexCommand \index{SDCC\_MODEL\_FLAT24}
9671 \begin_inset LatexCommand \index{Optimizations}
9678 SDCC performs a host of standard optimizations in addition to some MCU specific
9681 \layout Subsubsection
9683 Sub-expression Elimination
9684 \begin_inset LatexCommand \index{Subexpression elimination}
9691 The compiler does local and global common subexpression elimination, e.g.:
9702 will be translated to
9714 Some subexpressions are not as obvious as the above example, e.g.:
9724 In this case the address arithmetic a->b[i] will be computed only once;
9725 the equivalent code in C would be.
9737 The compiler will try to keep these temporary variables in registers.
9738 \layout Subsubsection
9740 Dead-Code Elimination
9741 \begin_inset LatexCommand \index{Dead-code elimination}
9760 i = 1; \SpecialChar ~
9765 global = 1;\SpecialChar ~
9778 global = 3;\SpecialChar ~
9789 int global; void f ()
9802 \layout Subsubsection
9805 \begin_inset LatexCommand \index{Copy propagation}
9861 Note: the dead stores created by this copy propagation will be eliminated
9862 by dead-code elimination.
9863 \layout Subsubsection
9866 \begin_inset LatexCommand \index{Loop optimization}
9873 Two types of loop optimizations are done by SDCC loop invariant lifting
9874 and strength reduction of loop induction variables.
9875 In addition to the strength reduction the optimizer marks the induction
9876 variables and the register allocator tries to keep the induction variables
9877 in registers for the duration of the loop.
9878 Because of this preference of the register allocator
9879 \begin_inset LatexCommand \index{Register allocation}
9883 , loop induction optimization causes an increase in register pressure, which
9884 may cause unwanted spilling of other temporary variables into the stack
9885 \begin_inset LatexCommand \index{stack}
9890 The compiler will generate a warning message when it is forced to allocate
9891 extra space either on the stack or data space.
9892 If this extra space allocation is undesirable then induction optimization
9893 can be eliminated either for the entire source file (with -
9903 -noinduction option) or for a given function only using #pragma\SpecialChar ~
9905 \begin_inset LatexCommand \index{\#pragma NOINDUCTION}
9918 for (i = 0 ; i < 100 ; i ++)
9932 for (i = 0; i < 100; i++)
9939 As mentioned previously some loop invariants are not as apparent, all static
9940 address computations are also moved out of the loop.
9945 \begin_inset LatexCommand \index{Strength reduction}
9949 , this optimization substitutes an expression by a cheaper expression:
9954 for (i=0;i < 100; i++)
9970 for (i=0;i< 100;i++) {
9974 ar[itemp1] = itemp2;
9987 The more expensive multiplication
9988 \begin_inset LatexCommand \index{Multiplication}
9992 is changed to a less expensive addition.
9993 \layout Subsubsection
9996 \begin_inset LatexCommand \index{Loop reversing}
10003 This optimization is done to reduce the overhead of checking loop boundaries
10004 for every iteration.
10005 Some simple loops can be reversed and implemented using a
10006 \begin_inset Quotes eld
10009 decrement and jump if not zero
10010 \begin_inset Quotes erd
10014 SDCC checks for the following criterion to determine if a loop is reversible
10015 (note: more sophisticated compilers use data-dependency analysis to make
10016 this determination, SDCC uses a more simple minded analysis).
10019 The 'for' loop is of the form
10025 for(<symbol> = <expression>; <sym> [< | <=] <expression>; [<sym>++ | <sym>
10035 The <for body> does not contain
10036 \begin_inset Quotes eld
10040 \begin_inset Quotes erd
10044 \begin_inset Quotes erd
10050 All goto's are contained within the loop.
10053 No function calls within the loop.
10056 The loop control variable <sym> is not assigned any value within the loop
10059 The loop control variable does NOT participate in any arithmetic operation
10063 There are NO switch statements in the loop.
10064 \layout Subsubsection
10066 Algebraic Simplifications
10069 SDCC does numerous algebraic simplifications, the following is a small sub-set
10070 of these optimizations.
10075 i = j + 0 ; /* changed to */ i = j;
10077 i /= 2; /* changed to */ i >>= 1;
10079 i = j - j ; /* changed to */ i = 0;
10081 i = j / 1 ; /* changed to */ i = j;
10084 Note the subexpressions
10085 \begin_inset LatexCommand \index{Subexpression}
10089 given above are generally introduced by macro expansions or as a result
10090 of copy/constant propagation.
10091 \layout Subsubsection
10093 'switch' Statements
10094 \begin_inset LatexCommand \index{switch statement}
10101 SDCC changes switch statements to jump tables
10102 \begin_inset LatexCommand \index{jump tables}
10106 when the following conditions are true.
10110 The case labels are in numerical sequence, the labels need not be in order,
10111 and the starting number need not be one or zero.
10117 switch(i) {\SpecialChar ~
10221 Both the above switch statements will be implemented using a jump-table.
10225 The number of case labels is at least three, since it takes two conditional
10226 statements to handle the boundary conditions.
10229 The number of case labels is less than 84, since each label takes 3 bytes
10230 and a jump-table can be utmost 256 bytes long.
10234 Switch statements which have gaps in the numeric sequence or those that
10235 have more that 84 case labels can be split into more than one switch statement
10236 for efficient code generation, e.g.:
10286 If the above switch statement is broken down into two switch statements
10325 case 9: \SpecialChar ~
10341 case 12:\SpecialChar ~
10348 then both the switch statements will be implemented using jump-tables whereas
10349 the unmodified switch statement will not be.
10350 \layout Subsubsection
10352 Bit-shifting Operations
10353 \begin_inset LatexCommand \index{Bit shifting}
10360 Bit shifting is one of the most frequently used operation in embedded programmin
10362 SDCC tries to implement bit-shift operations in the most efficient way
10378 generates the following code:
10392 In general SDCC will never setup a loop if the shift count is known.
10424 Note that SDCC stores numbers in little-endian format (i.e.
10425 lowest order first).
10426 \layout Subsubsection
10429 \begin_inset LatexCommand \index{Bit rotation}
10436 A special case of the bit-shift operation is bit rotation, SDCC recognizes
10437 the following expression to be a left bit-rotation:
10447 i = ((i << 1) | (i >> 7));
10456 will generate the following code:
10468 SDCC uses pattern matching on the parse tree to determine this operation.Variatio
10469 ns of this case will also be recognized as bit-rotation, i.e.:
10474 i = ((i >> 7) | (i << 1)); /* left-bit rotation */
10475 \layout Subsubsection
10478 \begin_inset LatexCommand \index{Highest Order Bit}
10485 It is frequently required to obtain the highest order bit of an integral
10486 type (long, int, short or char types).
10487 SDCC recognizes the following expression to yield the highest order bit
10488 and generates optimized code for it, e.g.:
10508 hob = (gint >> 15) & 1;
10518 will generate the following code:
10551 000A E5*01\SpecialChar ~
10577 000C 33\SpecialChar ~
10606 000D E4\SpecialChar ~
10635 000E 13\SpecialChar ~
10664 000F F5*02\SpecialChar ~
10691 Variations of this case however will
10696 It is a standard C expression, so I heartily recommend this be the only
10697 way to get the highest order bit, (it is portable).
10698 Of course it will be recognized even if it is embedded in other expressions,
10704 xyz = gint + ((gint >> 15) & 1);
10707 will still be recognized.
10708 \layout Subsubsection
10711 \begin_inset LatexCommand \index{Peephole optimizer}
10718 The compiler uses a rule based, pattern matching and re-writing mechanism
10719 for peep-hole optimization.
10724 a peep-hole optimizer by Christopher W.
10725 Fraser (cwfraser@microsoft.com).
10726 A default set of rules are compiled into the compiler, additional rules
10727 may be added with the
10740 \begin_inset LatexCommand \index{-\/-peep-file}
10747 The rule language is best illustrated with examples.
10771 The above rule will change the following assembly
10772 \begin_inset LatexCommand \index{Assembler routines}
10794 Note: All occurrences of a
10798 (pattern variable) must denote the same string.
10799 With the above rule, the assembly sequence:
10809 will remain unmodified.
10813 Other special case optimizations may be added by the user (via
10829 some variants of the 8051 MCU allow only
10838 The following two rules will change all
10857 replace { lcall %1 } by { acall %1 }
10859 replace { ljmp %1 } by { ajmp %1 }
10864 inline-assembler code
10866 is also passed through the peep hole optimizer, thus the peephole optimizer
10867 can also be used as an assembly level macro expander.
10868 The rules themselves are MCU dependent whereas the rule language infra-structur
10869 e is MCU independent.
10870 Peephole optimization rules for other MCU can be easily programmed using
10875 The syntax for a rule is as follows:
10880 rule := replace [ restart ] '{' <assembly sequence> '
10918 <assembly sequence> '
10936 '}' [if <functionName> ] '
10941 <assembly sequence> := assembly instruction (each instruction including
10942 labels must be on a separate line).
10946 The optimizer will apply to the rules one by one from the top in the sequence
10947 of their appearance, it will terminate when all rules are exhausted.
10948 If the 'restart' option is specified, then the optimizer will start matching
10949 the rules again from the top, this option for a rule is expensive (performance)
10950 , it is intended to be used in situations where a transformation will trigger
10951 the same rule again.
10952 An example of this (not a good one, it has side effects) is the following
10975 Note that the replace pattern cannot be a blank, but can be a comment line.
10976 Without the 'restart' option only the inner most 'pop' 'push' pair would
10977 be eliminated, i.e.:
11007 the restart option the rule will be applied again to the resulting code
11008 and then all the pop-push pairs will be eliminated to yield:
11018 A conditional function can be attached to a rule.
11019 Attaching rules are somewhat more involved, let me illustrate this with
11046 The optimizer does a look-up of a function name table defined in function
11051 in the source file SDCCpeeph.c, with the name
11056 If it finds a corresponding entry the function is called.
11057 Note there can be no parameters specified for these functions, in this
11062 is crucial, since the function
11066 expects to find the label in that particular variable (the hash table containin
11067 g the variable bindings is passed as a parameter).
11068 If you want to code more such functions, take a close look at the function
11069 labelInRange and the calling mechanism in source file SDCCpeeph.c.
11070 I know this whole thing is a little kludgey, but maybe some day we will
11071 have some better means.
11072 If you are looking at this file, you will also see the default rules that
11073 are compiled into the compiler, you can add your own rules in the default
11074 set there if you get tired of specifying the -
11088 \begin_inset LatexCommand \index{Pragmas}
11095 SDCC supports the following #pragma directives.
11099 \begin_inset LatexCommand \index{\#pragma SAVE}
11103 - this will save all current options to the SAVE/RESTORE stack.
11108 \begin_inset LatexCommand \index{\#pragma RESTORE}
11112 - will restore saved options from the last save.
11113 SAVEs & RESTOREs can be nested.
11114 SDCC uses a SAVE/RESTORE stack: SAVE pushes current options to the stack,
11115 RESTORE pulls current options from the stack.
11120 \begin_inset LatexCommand \index{\#pragma NOGCSE}
11124 - will stop global subexpression elimination.
11128 \begin_inset LatexCommand \index{\#pragma NOINDUCTION}
11132 - will stop loop induction optimizations.
11136 \begin_inset LatexCommand \index{\#pragma NOJTBOUND}
11140 - will not generate code for boundary value checking, when switch statements
11141 are turned into jump-tables.
11145 \begin_inset LatexCommand \index{\#pragma NOOVERLAY}
11149 - the compiler will not overlay the parameters and local variables of a
11154 \begin_inset LatexCommand \index{\#pragma LESS\_PEDANTIC}
11158 - the compiler will not warn you anymore for obvious mistakes, you'r on
11163 \begin_inset LatexCommand \index{\#pragma NOLOOPREVERSE}
11167 - Will not do loop reversal optimization
11171 \begin_inset LatexCommand \index{\#pragma EXCLUDE}
11175 NONE | {acc[,b[,dpl[,dph]]] - The exclude pragma disables generation of
11177 \begin_inset LatexCommand \index{push/pop}
11181 instruction in ISR function (using interrupt
11182 \begin_inset LatexCommand \index{interrupt}
11187 The directive should be placed immediately before the ISR function definition
11188 and it affects ALL ISR functions following it.
11189 To enable the normal register saving for ISR functions use #pragma\SpecialChar ~
11190 EXCLUDE\SpecialChar ~
11192 \begin_inset LatexCommand \index{\#pragma EXCLUDE}
11200 \begin_inset LatexCommand \index{\#pragma NOIV}
11204 - Do not generate interrupt vector table entries for all ISR functions
11205 defined after the pragma.
11206 This is useful in cases where the interrupt vector table must be defined
11207 manually, or when there is a secondary, manually defined interrupt vector
11209 for the autovector feature of the Cypress EZ-USB FX2).
11213 \begin_inset LatexCommand \index{\#pragma CALLEE-SAVES}
11218 \begin_inset LatexCommand \index{function prologue}
11222 function1[,function2[,function3...]] - The compiler by default uses a caller
11223 saves convention for register saving across function calls, however this
11224 can cause unneccessary register pushing & popping when calling small functions
11225 from larger functions.
11226 This option can be used to switch off the register saving convention for
11227 the function names specified.
11228 The compiler will not save registers when calling these functions, extra
11229 code need to be manually inserted at the entry & exit for these functions
11230 to save & restore the registers used by these functions, this can SUBSTANTIALLY
11231 reduce code & improve run time performance of the generated code.
11232 In the future the compiler (with interprocedural analysis) may be able
11233 to determine the appropriate scheme to use for each function call.
11244 -callee-saves command line option is used, the function names specified
11245 in #pragma\SpecialChar ~
11247 \begin_inset LatexCommand \index{\#pragma CALLEE-SAVES}
11251 is appended to the list of functions specified in the command line.
11254 The pragma's are intended to be used to turn-off certain optimizations which
11255 might cause the compiler to generate extra stack / data space to store
11256 compiler generated temporary variables.
11257 This usually happens in large functions.
11258 Pragma directives should be used as shown in the following example, they
11259 are used to control options & optimizations for a given function; pragmas
11260 should be placed before and/or after a function, placing pragma's inside
11261 a function body could have unpredictable results.
11267 \begin_inset LatexCommand \index{\#pragma SAVE}
11271 /* save the current settings */
11274 \begin_inset LatexCommand \index{\#pragma NOGCSE}
11278 /* turnoff global subexpression elimination */
11280 #pragma NOINDUCTION
11281 \begin_inset LatexCommand \index{\#pragma NOINDUCTION}
11285 /* turn off induction optimizations */
11308 \begin_inset LatexCommand \index{\#pragma RESTORE}
11312 /* turn the optimizations back on */
11315 The compiler will generate a warning message when extra space is allocated.
11316 It is strongly recommended that the SAVE and RESTORE pragma's be used when
11317 changing options for a function.
11322 <pending: this is messy and incomplete>
11327 Compiler support routines (_gptrget, _mulint etc)
11330 Stdclib functions (puts, printf, strcat etc)
11333 Math functions (sin, pow, sqrt etc)
11336 license statements for the libraries are missing
11339 Interfacing with Assembly Routines
11340 \begin_inset LatexCommand \index{Assembler routines}
11345 \layout Subsubsection
11347 Global Registers used for Parameter Passing
11348 \begin_inset LatexCommand \index{Parameter passing}
11355 The compiler always uses the global registers
11358 \begin_inset LatexCommand \index{DPTR, DPH, DPL}
11363 \begin_inset LatexCommand \index{B (register)}
11372 \begin_inset LatexCommand \index{ACC}
11378 to pass the first parameter to a routine.
11379 The second parameter onwards is either allocated on the stack (for reentrant
11390 -stack-auto is used) or in the internal / external ram (depending on the
11393 \layout Subsubsection
11395 Assembler Routine(non-reentrant
11396 \begin_inset LatexCommand \index{reentrant}
11401 \begin_inset LatexCommand \index{Assembler routines (non-reentrant)}
11408 In the following example the function cfunc calls an assembler routine asm_func,
11409 which takes two parameters.
11414 extern int asm_func(unsigned char, unsigned char);
11418 int c_func (unsigned char i, unsigned char j)
11426 return asm_func(i,j);
11440 return c_func(10,9);
11445 The corresponding assembler function is:
11450 .globl _asm_func_PARM_2
11514 add a,_asm_func_PARM_2
11535 \begin_inset LatexCommand \index{DPTR, DPH, DPL}
11552 Note here that the return values are placed in 'dpl' - One byte return value,
11553 'dpl' LSB & 'dph' MSB for two byte values.
11554 'dpl', 'dph' and 'b' for three byte values (generic pointers) and 'dpl','dph','
11555 b' & 'acc' for four byte values.
11558 The parameter naming convention is _<function_name>_PARM_<n>, where n is
11559 the parameter number starting from 1, and counting from the left.
11560 The first parameter is passed in
11561 \begin_inset Quotes eld
11565 \begin_inset Quotes erd
11568 for One bye parameter,
11569 \begin_inset Quotes eld
11573 \begin_inset Quotes erd
11577 \begin_inset Quotes eld
11581 \begin_inset Quotes erd
11584 for three bytes and
11585 \begin_inset Quotes eld
11589 \begin_inset Quotes erd
11592 for four bytes, the varible name for the second parameter will be _<function_na
11597 Assemble the assembler routine with the following command:
11604 asx8051 -losg asmfunc.asm
11611 Then compile and link the assembler routine to the C source file with the
11619 sdcc cfunc.c asmfunc.rel
11620 \layout Subsubsection
11622 Assembler Routine(reentrant
11623 \begin_inset LatexCommand \index{reentrant}
11628 \begin_inset LatexCommand \index{Assembler routines (reentrant)}
11635 In this case the second parameter onwards will be passed on the stack, the
11636 parameters are pushed from right to left i.e.
11637 after the call the left most parameter will be on the top of the stack.
11638 Here is an example:
11643 extern int asm_func(unsigned char, unsigned char);
11647 int c_func (unsigned char i, unsigned char j) reentrant
11655 return asm_func(i,j);
11669 return c_func(10,9);
11674 The corresponding assembler routine is:
11780 The compiling and linking procedure remains the same, however note the extra
11781 entry & exit linkage required for the assembler code, _bp is the stack
11782 frame pointer and is used to compute the offset into the stack for parameters
11783 and local variables.
11787 \begin_inset LatexCommand \index{stack}
11792 \begin_inset LatexCommand \index{External stack}
11799 The external stack is located at the start of the external ram segment,
11800 and is 256 bytes in size.
11811 -xstack option is used to compile the program, the parameters and local
11812 variables of all reentrant functions are allocated in this area.
11813 This option is provided for programs with large stack space requirements.
11814 When used with the -
11824 -stack-auto option, all parameters and local variables are allocated on
11825 the external stack (note support libraries will need to be recompiled with
11829 The compiler outputs the higher order address byte of the external ram segment
11830 into PORT P2, therefore when using the External Stack option, this port
11831 MAY NOT be used by the application program.
11835 \begin_inset LatexCommand \index{ANSI-compliance}
11842 Deviations from the compliancy.
11845 functions are not always reentrant.
11848 structures cannot be assigned values directly, cannot be passed as function
11849 parameters or assigned to each other and cannot be a return value from
11876 s1 = s2 ; /* is invalid in SDCC although allowed in ANSI */
11887 struct s foo1 (struct s parms) /* invalid in SDCC although allowed in ANSI
11909 return rets;/* is invalid in SDCC although allowed in ANSI */
11916 \begin_inset LatexCommand \index{long long (not supported)}
11921 \begin_inset LatexCommand \index{int (64 bit) (not supported)}
11929 \begin_inset LatexCommand \index{double (not supported)}
11933 ' precision floating point
11934 \begin_inset LatexCommand \index{Floating point support}
11941 No support for setjmp and longjmp (for now).
11945 \begin_inset LatexCommand \index{K\&R style}
11949 function declarations are NOT allowed.
11955 foo(i,j) /* this old style of function declarations */
11957 int i,j; /* are valid in ANSI but not valid in SDCC */
11972 functions declared as pointers must be dereferenced during the call.
11983 /* has to be called like this */
11985 (*foo)(); /* ansi standard allows calls to be made like 'foo()' */
11989 Cyclomatic Complexity
11990 \begin_inset LatexCommand \index{Cyclomatic complexity}
11997 Cyclomatic complexity of a function is defined as the number of independent
11998 paths the program can take during execution of the function.
11999 This is an important number since it defines the number test cases you
12000 have to generate to validate the function.
12001 The accepted industry standard for complexity number is 10, if the cyclomatic
12002 complexity reported by SDCC exceeds 10 you should think about simplification
12003 of the function logic.
12004 Note that the complexity level is not related to the number of lines of
12005 code in a function.
12006 Large functions can have low complexity, and small functions can have large
12012 SDCC uses the following formula to compute the complexity:
12017 complexity = (number of edges in control flow graph) - (number of nodes
12018 in control flow graph) + 2;
12022 Having said that the industry standard is 10, you should be aware that in
12023 some cases it be may unavoidable to have a complexity level of less than
12025 For example if you have switch statement with more than 10 case labels,
12026 each case label adds one to the complexity level.
12027 The complexity level is by no means an absolute measure of the algorithmic
12028 complexity of the function, it does however provide a good starting point
12029 for which functions you might look at for further optimization.
12035 Here are a few guidelines that will help the compiler generate more efficient
12036 code, some of the tips are specific to this compiler others are generally
12037 good programming practice.
12040 Use the smallest data type to represent your data-value.
12041 If it is known in advance that the value is going to be less than 256 then
12042 use an 'unsigned char' instead of a 'short' or 'int'.
12045 Use unsigned when it is known in advance that the value is not going to
12047 This helps especially if you are doing division or multiplication.
12050 NEVER jump into a LOOP.
12053 Declare the variables to be local whenever possible, especially loop control
12054 variables (induction).
12057 Since the compiler does not always do implicit integral promotion, the programme
12058 r should do an explicit cast when integral promotion is required.
12061 Reducing the size of division, multiplication & modulus operations can reduce
12062 code size substantially.
12063 Take the following code for example.
12069 foobar(unsigned int p1, unsigned char ch)
12077 unsigned char ch1 = p1 % ch ;
12088 For the modulus operation the variable ch will be promoted to unsigned int
12089 first then the modulus operation will be performed (this will lead to a
12090 call to support routine _moduint()), and the result will be casted to a
12092 If the code is changed to
12097 foobar(unsigned int p1, unsigned char ch)
12105 unsigned char ch1 = (unsigned char)p1 % ch ;
12116 It would substantially reduce the code generated (future versions of the
12117 compiler will be smart enough to detect such optimization opportunities).
12121 Notes on MCS51 memory
12122 \begin_inset LatexCommand \index{MCS51 memory}
12129 The 8051 family of microcontrollers have a minimum of 128 bytes of internal
12130 RAM memory which is structured as follows
12134 - Bytes 00-1F - 32 bytes to hold up to 4 banks of the registers R0 to R7,
12137 - Bytes 20-2F - 16 bytes to hold 128 bit variables and,
12139 - Bytes 30-7F - 80 bytes for general purpose use.
12144 Adittionally some members of the MCS51 family may have up to 128 bytes of
12145 additional, indirectly addressable, internal RAM memory (
12150 Furtermore, some chips may have some built in external memory (
12154 ) which should not be confused with the internal, direclty addressable RAM
12160 Usually this built in
12164 memory has to be activated before using it (you can probably find this
12165 information on the datasheet of the microcontroller your are using).
12168 Normally SDCC will only use the first bank
12169 \begin_inset LatexCommand \index{bank}
12173 of registers (register bank 0), but it is possible to specify that other
12174 banks of registers should be used in interrupt
12175 \begin_inset LatexCommand \index{interrupt}
12180 By default, the compiler will place the stack after the last byte of allocated
12181 memory for variables.
12182 For example, if the first 2 banks of registers are used, and only four
12187 variables, it will position the base of the internal stack at address 20
12189 This implies that as the stack
12190 \begin_inset LatexCommand \index{stack}
12194 grows, it will use up the remaining register banks, and the 16 bytes used
12195 by the 128 bit variables, and 80 bytes for general purpose use.
12196 If any bit variables are used, the data variables will be placed after
12197 the byte holding the last bit variable.
12198 For example, if register banks 0 and 1 are used, and there are 9 bit variables
12203 variables will be placed starting at address 0x22.
12215 \begin_inset LatexCommand \index{-\/-data-loc}
12219 to specify the start address of the
12233 -iram-size to specify the size of the total internal RAM (
12245 By default the 8051 linker will place the stack after the last byte of data
12258 \begin_inset LatexCommand \index{-\/-stack-loc}
12262 allows you to specify the start of the stack, i.e.
12263 you could start it after any data in the general purpose area.
12264 If your microcontroller has aditional indirectly addressable internal RAM
12269 ) you can place the stack on it.
12270 You may also need to use -
12281 \begin_inset LatexCommand \index{-\/-data-loc}
12285 to set the start address of the external RAM (
12300 \begin_inset LatexCommand \index{-\/-data-loc}
12304 to specify its size.
12305 Same goes for the code memory, using -
12316 \begin_inset LatexCommand \index{-\/-data-loc}
12331 \begin_inset LatexCommand \index{-\/-data-loc}
12336 If in doubt, don't specify any options and see if the resulting memory
12337 layout is appropiate, then you can twik it.
12340 The 8051 linker generates two files with memory allocation information.
12341 The first, with extension .map shows all the variables and segments.
12342 The second with extension .mem shows the final memory layout.
12343 The linker will complaint either if memory segments overlap, there is not
12344 enough memory, or there is not enough space for stack.
12345 If you get any linking warnings and/or errors related to stack or segments
12346 allocation, take a look at either the .map or .mem files to find out what
12348 The .mem file may even suggest a solution to the problem.
12352 \begin_inset LatexCommand \index{Tools}
12356 included in the distribution
12360 \begin_inset Tabular
12361 <lyxtabular version="3" rows="12" columns="3">
12363 <column alignment="center" valignment="top" leftline="true" width="0pt">
12364 <column alignment="center" valignment="top" leftline="true" width="0pt">
12365 <column alignment="center" valignment="top" leftline="true" rightline="true" width="0pt">
12366 <row topline="true" bottomline="true">
12367 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
12375 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
12383 <cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
12392 <row topline="true">
12393 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
12401 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
12406 Simulator for various architectures
12409 <cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
12418 <row topline="true">
12419 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
12427 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
12432 header file conversion
12435 <cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
12440 sdcc/support/scripts
12444 <row topline="true">
12445 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
12453 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
12458 header file conversion
12461 <cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
12466 sdcc/support/scripts
12470 <row topline="true">
12471 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
12479 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
12487 <cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
12505 <row topline="true">
12506 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
12514 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
12522 <cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
12540 <row topline="true">
12541 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
12549 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
12557 <cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
12575 <row topline="true">
12576 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
12584 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
12592 <cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
12610 <row topline="true">
12611 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
12619 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
12627 <cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
12645 <row topline="true">
12646 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
12654 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
12662 <cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
12680 <row topline="true">
12681 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
12689 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
12697 <cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
12715 <row topline="true" bottomline="true">
12716 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
12724 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
12732 <cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
12757 Related open source tools
12758 \begin_inset LatexCommand \index{Related tools}
12766 \begin_inset Tabular
12767 <lyxtabular version="3" rows="7" columns="3">
12769 <column alignment="center" valignment="top" leftline="true" width="0pt">
12770 <column alignment="center" valignment="top" leftline="true" width="0pt">
12771 <column alignment="center" valignment="top" leftline="true" rightline="true" width="0pt">
12772 <row topline="true" bottomline="true">
12773 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
12781 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
12789 <cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
12798 <row topline="true">
12799 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
12805 \begin_inset LatexCommand \index{gpsim}
12812 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
12820 <cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
12826 \begin_inset LatexCommand \url{http://www.dattalo.com/gnupic/gpsim.html}
12834 <row topline="true">
12835 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
12841 \begin_inset LatexCommand \index{srecord}
12848 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
12853 Object file conversion, checksumming, ...
12856 <cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
12862 \begin_inset LatexCommand \url{http://srecord.sourceforge.net/}
12870 <row topline="true">
12871 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
12877 \begin_inset LatexCommand \index{objdump}
12884 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
12889 Object file conversion, ...
12892 <cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
12897 Part of binutils (should be there anyway)
12901 <row topline="true">
12902 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
12908 \begin_inset LatexCommand \index{doxygen}
12915 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
12920 Source code documentation system
12923 <cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
12929 \begin_inset LatexCommand \url{http://www.doxygen.org}
12937 <row topline="true">
12938 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
12944 \begin_inset LatexCommand \index{splint}
12951 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
12956 Statically checks c sources
12959 <cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
12965 \begin_inset LatexCommand \url{http://www.splint.org}
12973 <row topline="true" bottomline="true">
12974 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
12980 \begin_inset LatexCommand \index{ddd}
12987 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
12992 Debugger, serves nicely as GUI to sdcdb
12993 \begin_inset LatexCommand \index{sdcdb}
13000 <cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
13006 \begin_inset LatexCommand \url{http://www.gnu.org/software/ddd/}
13021 Related documentation / recommended reading
13025 \begin_inset Tabular
13026 <lyxtabular version="3" rows="5" columns="3">
13028 <column alignment="center" valignment="top" leftline="true" width="0pt">
13029 <column alignment="center" valignment="top" leftline="true" width="0pt">
13030 <column alignment="center" valignment="top" leftline="true" rightline="true" width="0pt">
13031 <row topline="true" bottomline="true">
13032 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
13040 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
13048 <cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
13057 <row topline="true">
13058 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
13068 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
13073 Advanced Compiler Design and Implementation
13076 <cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
13085 <row topline="true">
13086 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
13103 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
13109 \begin_inset LatexCommand \index{C Reference card}
13116 <cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
13122 \begin_inset LatexCommand \url{http://www.refcards.com/about/c.html}
13130 <row topline="true">
13131 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
13136 test_suite_spec.pdf
13139 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
13144 sdcc regression test
13145 \begin_inset LatexCommand \index{Regression test}
13152 <cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
13161 <row topline="true" bottomline="true">
13162 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
13188 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
13193 sdcc internal documentation
13196 <cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
13212 Retargetting for other MCUs.
13215 The issues for retargetting the compiler are far too numerous to be covered
13217 What follows is a brief description of each of the seven phases of the
13218 compiler and its MCU dependency.
13221 Parsing the source and building the annotated parse tree.
13222 This phase is largely MCU independent (except for the language extensions).
13223 Syntax & semantic checks are also done in this phase, along with some initial
13224 optimizations like back patching labels and the pattern matching optimizations
13225 like bit-rotation etc.
13228 The second phase involves generating an intermediate code which can be easy
13229 manipulated during the later phases.
13230 This phase is entirely MCU independent.
13231 The intermediate code generation assumes the target machine has unlimited
13232 number of registers, and designates them with the name iTemp.
13233 The compiler can be made to dump a human readable form of the code generated
13247 This phase does the bulk of the standard optimizations and is also MCU independe
13249 This phase can be broken down into several sub-phases:
13253 Break down intermediate code (iCode) into basic blocks.
13255 Do control flow & data flow analysis on the basic blocks.
13257 Do local common subexpression elimination, then global subexpression elimination
13259 Dead code elimination
13263 If loop optimizations caused any changes then do 'global subexpression eliminati
13264 on' and 'dead code elimination' again.
13267 This phase determines the live-ranges; by live range I mean those iTemp
13268 variables defined by the compiler that still survive after all the optimization
13270 Live range analysis
13271 \begin_inset LatexCommand \index{Live range analysis}
13275 is essential for register allocation, since these computation determines
13276 which of these iTemps will be assigned to registers, and for how long.
13279 Phase five is register allocation.
13280 There are two parts to this process.
13284 The first part I call 'register packing' (for lack of a better term).
13285 In this case several MCU specific expression folding is done to reduce
13290 The second part is more MCU independent and deals with allocating registers
13291 to the remaining live ranges.
13292 A lot of MCU specific code does creep into this phase because of the limited
13293 number of index registers available in the 8051.
13296 The Code generation phase is (unhappily), entirely MCU dependent and very
13297 little (if any at all) of this code can be reused for other MCU.
13298 However the scheme for allocating a homogenized assembler operand for each
13299 iCode operand may be reused.
13302 As mentioned in the optimization section the peep-hole optimizer is rule
13303 based system, which can reprogrammed for other MCUs.
13307 \begin_inset LatexCommand \index{sdcdb}
13311 - Source Level Debugger
13312 \begin_inset LatexCommand \index{Debugger}
13319 SDCC is distributed with a source level debugger.
13320 The debugger uses a command line interface, the command repertoire of the
13321 debugger has been kept as close to gdb
13322 \begin_inset LatexCommand \index{gdb}
13326 (the GNU debugger) as possible.
13327 The configuration and build process is part of the standard compiler installati
13328 on, which also builds and installs the debugger in the target directory
13329 specified during configuration.
13330 The debugger allows you debug BOTH at the C source and at the ASM source
13334 Compiling for Debugging
13337 The \SpecialChar \-
13339 debug option must be specified for all files for which debug information
13340 is to be generated.
13341 The complier generates a .adb file for each of these files.
13342 The linker creates the .cdb file from the .adb files and the address information.
13343 This .cdb is used by the debugger.
13346 How the Debugger Works
13359 -debug option is specified the compiler generates extra symbol information
13360 some of which are put into the the assembler source and some are put into
13362 Then the linker creates the .cdb file from the individual .adb files with
13363 the address information for the symbols.
13364 The debugger reads the symbolic information generated by the compiler &
13365 the address information generated by the linker.
13366 It uses the SIMULATOR (Daniel's S51) to execute the program, the program
13367 execution is controlled by the debugger.
13368 When a command is issued for the debugger, it translates it into appropriate
13369 commands for the simulator.
13372 Starting the Debugger
13375 The debugger can be started using the following command line.
13376 (Assume the file you are debugging has the file name foo).
13390 The debugger will look for the following files.
13393 foo.c - the source file.
13396 foo.cdb - the debugger symbol information file.
13399 foo.ihx - the intel hex format
13400 \begin_inset LatexCommand \index{Intel hex format}
13407 Command Line Options.
13420 -directory=<source file directory> this option can used to specify the directory
13422 The debugger will look into the directory list specified for source, cdb
13424 The items in the directory list must be separated by ':', e.g.
13425 if the source files can be in the directories /home/src1 and /home/src2,
13436 -directory option should be -
13446 -directory=/home/src1:/home/src2.
13447 Note there can be no spaces in the option.
13451 -cd <directory> - change to the <directory>.
13454 -fullname - used by GUI front ends.
13457 -cpu <cpu-type> - this argument is passed to the simulator please see the
13458 simulator docs for details.
13461 -X <Clock frequency > this options is passed to the simulator please see
13462 the simulator docs for details.
13465 -s <serial port file> passed to simulator see the simulator docs for details.
13468 -S <serial in,out> passed to simulator see the simulator docs for details.
13474 As mention earlier the command interface for the debugger has been deliberately
13475 kept as close the GNU debugger gdb, as possible.
13476 This will help the integration with existing graphical user interfaces
13477 (like ddd, xxgdb or xemacs) existing for the GNU debugger.
13478 \layout Subsubsection
13480 break [line | file:line | function | file:function]
13483 Set breakpoint at specified line or function:
13492 sdcdb>break foo.c:100
13494 sdcdb>break funcfoo
13496 sdcdb>break foo.c:funcfoo
13497 \layout Subsubsection
13499 clear [line | file:line | function | file:function ]
13502 Clear breakpoint at specified line or function:
13511 sdcdb>clear foo.c:100
13513 sdcdb>clear funcfoo
13515 sdcdb>clear foo.c:funcfoo
13516 \layout Subsubsection
13521 Continue program being debugged, after breakpoint.
13522 \layout Subsubsection
13527 Execute till the end of the current function.
13528 \layout Subsubsection
13533 Delete breakpoint number 'n'.
13534 If used without any option clear ALL user defined break points.
13535 \layout Subsubsection
13537 info [break | stack | frame | registers ]
13540 info break - list all breakpoints
13543 info stack - show the function call stack.
13546 info frame - show information about the current execution frame.
13549 info registers - show content of all registers.
13550 \layout Subsubsection
13555 Step program until it reaches a different source line.
13556 \layout Subsubsection
13561 Step program, proceeding through subroutine calls.
13562 \layout Subsubsection
13567 Start debugged program.
13568 \layout Subsubsection
13573 Print type information of the variable.
13574 \layout Subsubsection
13579 print value of variable.
13580 \layout Subsubsection
13585 load the given file name.
13586 Note this is an alternate method of loading file for debugging.
13587 \layout Subsubsection
13592 print information about current frame.
13593 \layout Subsubsection
13598 Toggle between C source & assembly source.
13599 \layout Subsubsection
13601 ! simulator command
13604 Send the string following '!' to the simulator, the simulator response is
13606 Note the debugger does not interpret the command being sent to the simulator,
13607 so if a command like 'go' is sent the debugger can loose its execution
13608 context and may display incorrect values.
13609 \layout Subsubsection
13616 My name is Bobby Brown"
13619 Interfacing with XEmacs
13620 \begin_inset LatexCommand \index{XEmacs}
13625 \begin_inset LatexCommand \index{Emacs}
13632 Two files (in emacs lisp) are provided for the interfacing with XEmacs,
13633 sdcdb.el and sdcdbsrc.el.
13634 These two files can be found in the $(prefix)/bin directory after the installat
13636 These files need to be loaded into XEmacs for the interface to work.
13637 This can be done at XEmacs startup time by inserting the following into
13638 your '.xemacs' file (which can be found in your HOME directory):
13644 (load-file sdcdbsrc.el)
13650 .xemacs is a lisp file so the () around the command is REQUIRED.
13651 The files can also be loaded dynamically while XEmacs is running, set the
13652 environment variable 'EMACSLOADPATH' to the installation bin directory
13653 (<installdir>/bin), then enter the following command ESC-x load-file sdcdbsrc.
13654 To start the interface enter the following command:
13668 You will prompted to enter the file name to be debugged.
13673 The command line options that are passed to the simulator directly are bound
13674 to default values in the file sdcdbsrc.el.
13675 The variables are listed below, these values maybe changed as required.
13678 sdcdbsrc-cpu-type '51
13681 sdcdbsrc-frequency '11059200
13684 sdcdbsrc-serial nil
13687 The following is a list of key mapping for the debugger interface.
13695 ;; Current Listing ::
13697 ;;key\SpecialChar ~
13712 binding\SpecialChar ~
13736 ;;---\SpecialChar ~
13751 ------\SpecialChar ~
13791 sdcdb-next-from-src\SpecialChar ~
13817 sdcdb-back-from-src\SpecialChar ~
13843 sdcdb-cont-from-src\SpecialChar ~
13853 SDCDB continue command
13869 sdcdb-step-from-src\SpecialChar ~
13895 sdcdb-whatis-c-sexp\SpecialChar ~
13905 SDCDB ptypecommand for data at
13969 sdcdbsrc-delete\SpecialChar ~
13983 SDCDB Delete all breakpoints if no arg
14031 given or delete arg (C-u arg x)
14047 sdcdbsrc-frame\SpecialChar ~
14062 SDCDB Display current frame if no arg,
14111 given or display frame arg
14176 sdcdbsrc-goto-sdcdb\SpecialChar ~
14186 Goto the SDCDB output buffer
14202 sdcdb-print-c-sexp\SpecialChar ~
14213 SDCDB print command for data at
14277 sdcdbsrc-goto-sdcdb\SpecialChar ~
14287 Goto the SDCDB output buffer
14303 sdcdbsrc-mode\SpecialChar ~
14319 Toggles Sdcdbsrc mode (turns it off)
14323 ;; C-c C-f\SpecialChar ~
14331 sdcdb-finish-from-src\SpecialChar ~
14339 SDCDB finish command
14343 ;; C-x SPC\SpecialChar ~
14351 sdcdb-break\SpecialChar ~
14369 Set break for line with point
14371 ;; ESC t\SpecialChar ~
14381 sdcdbsrc-mode\SpecialChar ~
14397 Toggle Sdcdbsrc mode
14399 ;; ESC m\SpecialChar ~
14409 sdcdbsrc-srcmode\SpecialChar ~
14433 The Z80 and gbz80 port
14436 SDCC can target both the Zilog Z80 and the Nintendo Gameboy's Z80-like gbz80.
14437 The port is incomplete - long support is incomplete (mul, div and mod are
14438 unimplimented), and both float and bitfield support is missing.
14439 Apart from that the code generated is correct.
14442 As always, the code is the authoritave reference - see z80/ralloc.c and z80/gen.c.
14443 The stack frame is similar to that generated by the IAR Z80 compiler.
14444 IX is used as the base pointer, HL is used as a temporary register, and
14445 BC and DE are available for holding varibles.
14446 IY is currently unusued.
14447 Return values are stored in HL.
14448 One bad side effect of using IX as the base pointer is that a functions
14449 stack frame is limited to 127 bytes - this will be fixed in a later version.
14453 \begin_inset LatexCommand \index{Support}
14460 SDCC has grown to be a large project.
14461 The compiler alone (without the preprocessor, assembler and linker) is
14462 about 40,000 lines of code (blank stripped).
14463 The open source nature of this project is a key to its continued growth
14465 You gain the benefit and support of many active software developers and
14467 Is SDCC perfect? No, that's why we need your help.
14468 The developers take pride in fixing reported bugs.
14469 You can help by reporting the bugs and helping other SDCC users.
14470 There are lots of ways to contribute, and we encourage you to take part
14471 in making SDCC a great software package.
14475 The SDCC project is hosted on the sdcc sourceforge site at
14476 \begin_inset LatexCommand \htmlurl{http://sourceforge.net/projects/sdcc}
14481 You'll find the complete set of mailing lists
14482 \begin_inset LatexCommand \index{Mailing list}
14486 , forums, bug reporting system, patch submission
14487 \begin_inset LatexCommand \index{Patch submission}
14492 \begin_inset LatexCommand \index{download}
14496 area and cvs code repository
14497 \begin_inset LatexCommand \index{cvs code repository}
14505 \begin_inset LatexCommand \index{Bugs}
14510 \begin_inset LatexCommand \index{Reporting bugs}
14517 The recommended way of reporting bugs is using the infrastructure of the
14519 You can follow the status of bug reports there and have an overview about
14523 Bug reports are automatically forwarded to the developer mailing list and
14524 will be fixed ASAP.
14525 When reporting a bug, it is very useful to include a small test program
14526 which reproduces the problem.
14527 If you can isolate the problem by looking at the generated assembly code,
14528 this can be very helpful.
14529 Compiling your program with the -
14540 \begin_inset LatexCommand \index{-\/-dumpall}
14544 option can sometimes be useful in locating optimization problems.
14547 Please have a short check that you are using a recent version of SDCC and
14548 the bug is not yet known.
14549 This is the link for reporting bugs:
14550 \begin_inset LatexCommand \htmlurl{http://sourceforge.net/tracker/?group_id=599&atid=100599}
14557 Requesting Features
14558 \begin_inset LatexCommand \index{Feature request}
14563 \begin_inset LatexCommand \index{Requesting features}
14570 Like bug reports feature requests are forwarded to the developer mailing
14572 This is the link for requesting features:
14573 \begin_inset LatexCommand \htmlurl{http://sourceforge.net/tracker/?group_id=599&atid=350599}
14583 These links should take you directly to the
14584 \begin_inset LatexCommand \url[Mailing lists]{http://sourceforge.net/mail/?group_id=599}
14594 Traffic on sdcc-devel and sdcc-user is about 100 mails/month each not counting
14595 automated messages (mid 2003)
14599 \begin_inset LatexCommand \url[Forums]{http://sourceforge.net/forum/?group_id=599}
14603 , lists and forums are archived so if you are lucky someone already had
14608 \begin_inset LatexCommand \index{Changelog}
14615 You can follow the status of the cvs version
14616 \begin_inset LatexCommand \index{version}
14620 of SDCC by watching the file
14621 \begin_inset LatexCommand \htmlurl[ChangeLog]{http://cvs.sourceforge.net/cgi-bin/viewcvs.cgi/*checkout*/sdcc/sdcc/ChangeLog?rev=HEAD&content-type=text/plain}
14625 in the cvs-repository.
14629 \begin_inset LatexCommand \index{Release policy}
14636 Historically there often were long delays between official releases and
14637 the sourceforge download area tends to get not updated at all.
14638 Current excuses might refer to problems with live range analysis, but if
14639 this is fixed, the next problem rising is that another excuse will have
14641 Kidding aside, we have to get better there!
14645 \begin_inset LatexCommand \index{Examples}
14652 You'll find some small examples in the directory sdcc/device/examples/
14655 Maybe we should include some links to real world applications.
14656 Preferrably pointer to pointers (one for each architecture) so this stays
14661 \begin_inset LatexCommand \index{Quality control}
14668 The compiler is passed through nightly compile and build checks.
14674 \begin_inset LatexCommand \index{Regression test}
14678 check that SDCC itself compiles flawlessly on several platforms and checks
14679 the quality of the code generated by SDCC by running the code through simulator
14681 There is a separate document
14684 \begin_inset LatexCommand \index{Test suite}
14693 You'll find the test code in the directory
14695 sdcc/support/regression
14698 You can run these tests manually by running
14702 in this directory (or f.e.
14707 if you don't want to run the complete tests).
14708 The test code might also be interesting if you want to look for examples
14709 \begin_inset LatexCommand \index{Examples}
14713 checking corner cases of SDCC or if you plan to submit patches
14714 \begin_inset LatexCommand \index{Patch submission}
14721 The pic port uses a different set of regression tests, you'll find them
14724 sdcc/src/regression
14730 \begin_inset LatexCommand \index{Compiler internals}
14737 The anatomy of the compiler
14742 This is an excerpt from an atricle published in Circuit Cellar MagaZine
14744 It's a little outdated (the compiler is much more efficient now and user/develo
14745 per friendly), but pretty well exposes the guts of it all.
14751 The current version of SDCC can generate code for Intel 8051 and Z80 MCU.
14752 It is fairly easy to retarget for other 8-bit MCU.
14753 Here we take a look at some of the internals of the compiler.
14758 \begin_inset LatexCommand \index{Parsing}
14765 Parsing the input source file and creating an AST (Annotated Syntax Tree
14766 \begin_inset LatexCommand \index{Annotated syntax tree}
14771 This phase also involves propagating types (annotating each node of the
14772 parse tree with type information) and semantic analysis.
14773 There are some MCU specific parsing rules.
14774 For example the storage classes, the extended storage classes are MCU specific
14775 while there may be a xdata storage class for 8051 there is no such storage
14776 class for z80 or Atmel AVR.
14777 SDCC allows MCU specific storage class extensions, i.e.
14778 xdata will be treated as a storage class specifier when parsing 8051 C
14779 code but will be treated as a C identifier when parsing z80 or ATMEL AVR
14784 \begin_inset LatexCommand \index{iCode}
14791 Intermediate code generation.
14792 In this phase the AST is broken down into three-operand form (iCode).
14793 These three operand forms are represented as doubly linked lists.
14794 ICode is the term given to the intermediate form generated by the compiler.
14795 ICode example section shows some examples of iCode generated for some simple
14796 C source functions.
14800 \begin_inset LatexCommand \index{Optimizations}
14807 Bulk of the target independent optimizations is performed in this phase.
14808 The optimizations include constant propagation, common sub-expression eliminati
14809 on, loop invariant code movement, strength reduction of loop induction variables
14810 and dead-code elimination.
14813 Live range analysis
14814 \begin_inset LatexCommand \index{Live range analysis}
14821 During intermediate code generation phase, the compiler assumes the target
14822 machine has infinite number of registers and generates a lot of temporary
14824 The live range computation determines the lifetime of each of these compiler-ge
14825 nerated temporaries.
14826 A picture speaks a thousand words.
14827 ICode example sections show the live range annotations for each of the
14829 It is important to note here, each iCode is assigned a number in the order
14830 of its execution in the function.
14831 The live ranges are computed in terms of these numbers.
14832 The from number is the number of the iCode which first defines the operand
14833 and the to number signifies the iCode which uses this operand last.
14836 Register Allocation
14837 \begin_inset LatexCommand \index{Register allocation}
14844 The register allocation determines the type and number of registers needed
14846 In most MCUs only a few registers can be used for indirect addressing.
14847 In case of 8051 for example the registers R0 & R1 can be used to indirectly
14848 address the internal ram and DPTR to indirectly address the external ram.
14849 The compiler will try to allocate the appropriate register to pointer variables
14851 ICode example section shows the operands annotated with the registers assigned
14853 The compiler will try to keep operands in registers as much as possible;
14854 there are several schemes the compiler uses to do achieve this.
14855 When the compiler runs out of registers the compiler will check to see
14856 if there are any live operands which is not used or defined in the current
14857 basic block being processed, if there are any found then it will push that
14858 operand and use the registers in this block, the operand will then be popped
14859 at the end of the basic block.
14863 There are other MCU specific considerations in this phase.
14864 Some MCUs have an accumulator; very short-lived operands could be assigned
14865 to the accumulator instead of general-purpose register.
14871 Figure II gives a table of iCode operations supported by the compiler.
14872 The code generation involves translating these operations into corresponding
14873 assembly code for the processor.
14874 This sounds overly simple but that is the essence of code generation.
14875 Some of the iCode operations are generated on a MCU specific manner for
14876 example, the z80 port does not use registers to pass parameters so the
14877 SEND and RECV iCode operations will not be generated, and it also does
14878 not support JUMPTABLES.
14885 <Where is Figure II ?>
14889 \begin_inset LatexCommand \index{iCode}
14896 This section shows some details of iCode.
14897 The example C code does not do anything useful; it is used as an example
14898 to illustrate the intermediate code generated by the compiler.
14910 /* This function does nothing useful.
14917 for the purpose of explaining iCode */
14920 short function (data int *x)
14928 short i=10; /* dead initialization eliminated */
14933 short sum=10; /* dead initialization eliminated */
14946 while (*x) *x++ = *p++;
14960 /* compiler detects i,j to be induction variables */
14964 for (i = 0, j = 10 ; i < 10 ; i++, j--) {
14976 mul += i * 3; /* this multiplication remains */
14982 gint += j * 3;/* this multiplication changed to addition */
14996 In addition to the operands each iCode contains information about the filename
14997 and line it corresponds to in the source file.
14998 The first field in the listing should be interpreted as follows:
15003 Filename(linenumber: iCode Execution sequence number : ICode hash table
15004 key : loop depth of the iCode).
15009 Then follows the human readable form of the ICode operation.
15010 Each operand of this triplet form can be of three basic types a) compiler
15011 generated temporary b) user defined variable c) a constant value.
15012 Note that local variables and parameters are replaced by compiler generated
15015 \begin_inset LatexCommand \index{Live range analysis}
15019 are computed only for temporaries (i.e.
15020 live ranges are not computed for global variables).
15022 \begin_inset LatexCommand \index{Register allocation}
15026 are allocated for temporaries only.
15027 Operands are formatted in the following manner:
15032 Operand Name [lr live-from : live-to ] { type information } [ registers
15038 As mentioned earlier the live ranges are computed in terms of the execution
15039 sequence number of the iCodes, for example
15041 the iTemp0 is live from (i.e.
15042 first defined in iCode with execution sequence number 3, and is last used
15043 in the iCode with sequence number 5).
15044 For induction variables such as iTemp21 the live range computation extends
15045 the lifetime from the start to the end of the loop.
15047 The register allocator used the live range information to allocate registers,
15048 the same registers may be used for different temporaries if their live
15049 ranges do not overlap, for example r0 is allocated to both iTemp6 and to
15050 iTemp17 since their live ranges do not overlap.
15051 In addition the allocator also takes into consideration the type and usage
15052 of a temporary, for example itemp6 is a pointer to near space and is used
15053 as to fetch data from (i.e.
15054 used in GET_VALUE_AT_ADDRESS) so it is allocated a pointer registers (r0).
15055 Some short lived temporaries are allocated to special registers which have
15056 meaning to the code generator e.g.
15057 iTemp13 is allocated to a pseudo register CC which tells the back end that
15058 the temporary is used only for a conditional jump the code generation makes
15059 use of this information to optimize a compare and jump ICode.
15061 There are several loop optimizations
15062 \begin_inset LatexCommand \index{Loop optimization}
15066 performed by the compiler.
15067 It can detect induction variables iTemp21(i) and iTemp23(j).
15068 Also note the compiler does selective strength reduction
15069 \begin_inset LatexCommand \index{Strength reduction}
15074 the multiplication of an induction variable in line 18 (gint = j * 3) is
15075 changed to addition, a new temporary iTemp17 is allocated and assigned
15076 a initial value, a constant 3 is then added for each iteration of the loop.
15077 The compiler does not change the multiplication
15078 \begin_inset LatexCommand \index{Multiplication}
15082 in line 17 however since the processor does support an 8 * 8 bit multiplication.
15084 Note the dead code elimination
15085 \begin_inset LatexCommand \index{Dead-code elimination}
15089 optimization eliminated the dead assignments in line 7 & 8 to I and sum
15097 Sample.c (5:1:0:0) _entry($9) :
15102 Sample.c(5:2:1:0) proc _function [lr0:0]{function short}
15107 Sample.c(11:3:2:0) iTemp0 [lr3:5]{_near * int}[r2] = recv
15112 Sample.c(11:4:53:0) preHeaderLbl0($11) :
15117 Sample.c(11:5:55:0) iTemp6 [lr5:16]{_near * int}[r0] := iTemp0 [lr3:5]{_near
15123 Sample.c(11:6:5:1) _whilecontinue_0($1) :
15128 Sample.c(11:7:7:1) iTemp4 [lr7:8]{int}[r2 r3] = @[iTemp6 [lr5:16]{_near *
15134 Sample.c(11:8:8:1) if iTemp4 [lr7:8]{int}[r2 r3] == 0 goto _whilebreak_0($3)
15139 Sample.c(11:9:14:1) iTemp7 [lr9:13]{_far * int}[DPTR] := _p [lr0:0]{_far
15145 Sample.c(11:10:15:1) _p [lr0:0]{_far * int} = _p [lr0:0]{_far * int} + 0x2
15151 Sample.c(11:13:18:1) iTemp10 [lr13:14]{int}[r2 r3] = @[iTemp7 [lr9:13]{_far
15157 Sample.c(11:14:19:1) *(iTemp6 [lr5:16]{_near * int}[r0]) := iTemp10 [lr13:14]{int
15163 Sample.c(11:15:12:1) iTemp6 [lr5:16]{_near * int}[r0] = iTemp6 [lr5:16]{_near
15164 * int}[r0] + 0x2 {short}
15169 Sample.c(11:16:20:1) goto _whilecontinue_0($1)
15174 Sample.c(11:17:21:0)_whilebreak_0($3) :
15179 Sample.c(12:18:22:0) iTemp2 [lr18:40]{short}[r2] := 0x0 {short}
15184 Sample.c(13:19:23:0) iTemp11 [lr19:40]{short}[r3] := 0x0 {short}
15189 Sample.c(15:20:54:0)preHeaderLbl1($13) :
15194 Sample.c(15:21:56:0) iTemp21 [lr21:38]{short}[r4] := 0x0 {short}
15199 Sample.c(15:22:57:0) iTemp23 [lr22:38]{int}[r5 r6] := 0xa {int}
15204 Sample.c(15:23:58:0) iTemp17 [lr23:38]{int}[r7 r0] := 0x1e {int}
15209 Sample.c(15:24:26:1)_forcond_0($4) :
15214 Sample.c(15:25:27:1) iTemp13 [lr25:26]{char}[CC] = iTemp21 [lr21:38]{short}[r4]
15220 Sample.c(15:26:28:1) if iTemp13 [lr25:26]{char}[CC] == 0 goto _forbreak_0($7)
15225 Sample.c(16:27:31:1) iTemp2 [lr18:40]{short}[r2] = iTemp2 [lr18:40]{short}[r2]
15226 + ITemp21 [lr21:38]{short}[r4]
15231 Sample.c(17:29:33:1) iTemp15 [lr29:30]{short}[r1] = iTemp21 [lr21:38]{short}[r4]
15237 Sample.c(17:30:34:1) iTemp11 [lr19:40]{short}[r3] = iTemp11 [lr19:40]{short}[r3]
15238 + iTemp15 [lr29:30]{short}[r1]
15243 Sample.c(18:32:36:1:1) iTemp17 [lr23:38]{int}[r7 r0]= iTemp17 [lr23:38]{int}[r7
15249 Sample.c(18:33:37:1) _gint [lr0:0]{int} = _gint [lr0:0]{int} + iTemp17 [lr23:38]{
15255 Sample.c(15:36:42:1) iTemp21 [lr21:38]{short}[r4] = iTemp21 [lr21:38]{short}[r4]
15261 Sample.c(15:37:45:1) iTemp23 [lr22:38]{int}[r5 r6]= iTemp23 [lr22:38]{int}[r5
15267 Sample.c(19:38:47:1) goto _forcond_0($4)
15272 Sample.c(19:39:48:0)_forbreak_0($7) :
15277 Sample.c(20:40:49:0) iTemp24 [lr40:41]{short}[DPTR] = iTemp2 [lr18:40]{short}[r2]
15278 + ITemp11 [lr19:40]{short}[r3]
15283 Sample.c(20:41:50:0) ret iTemp24 [lr40:41]{short}
15288 Sample.c(20:42:51:0)_return($8) :
15293 Sample.c(20:43:52:0) eproc _function [lr0:0]{ ia0 re0 rm0}{function short}
15299 Finally the code generated for this function:
15340 ; ----------------------------------------------
15345 ; function function
15350 ; ----------------------------------------------
15360 ; iTemp0 [lr3:5]{_near * int}[r2] = recv
15372 ; iTemp6 [lr5:16]{_near * int}[r0] := iTemp0 [lr3:5]{_near * int}[r2]
15384 ;_whilecontinue_0($1) :
15394 ; iTemp4 [lr7:8]{int}[r2 r3] = @[iTemp6 [lr5:16]{_near * int}[r0]]
15399 ; if iTemp4 [lr7:8]{int}[r2 r3] == 0 goto _whilebreak_0($3)
15458 ; iTemp7 [lr9:13]{_far * int}[DPTR] := _p [lr0:0]{_far * int}
15477 ; _p [lr0:0]{_far * int} = _p [lr0:0]{_far * int} + 0x2 {short}
15524 ; iTemp10 [lr13:14]{int}[r2 r3] = @[iTemp7 [lr9:13]{_far * int}[DPTR]]
15564 ; *(iTemp6 [lr5:16]{_near * int}[r0]) := iTemp10 [lr13:14]{int}[r2 r3]
15590 ; iTemp6 [lr5:16]{_near * int}[r0] =
15595 ; iTemp6 [lr5:16]{_near * int}[r0] +
15612 ; goto _whilecontinue_0($1)
15624 ; _whilebreak_0($3) :
15634 ; iTemp2 [lr18:40]{short}[r2] := 0x0 {short}
15646 ; iTemp11 [lr19:40]{short}[r3] := 0x0 {short}
15658 ; iTemp21 [lr21:38]{short}[r4] := 0x0 {short}
15670 ; iTemp23 [lr22:38]{int}[r5 r6] := 0xa {int}
15689 ; iTemp17 [lr23:38]{int}[r7 r0] := 0x1e {int}
15718 ; iTemp13 [lr25:26]{char}[CC] = iTemp21 [lr21:38]{short}[r4] < 0xa {short}
15723 ; if iTemp13 [lr25:26]{char}[CC] == 0 goto _forbreak_0($7)
15768 ; iTemp2 [lr18:40]{short}[r2] = iTemp2 [lr18:40]{short}[r2] +
15773 ; iTemp21 [lr21:38]{short}[r4]
15799 ; iTemp15 [lr29:30]{short}[r1] = iTemp21 [lr21:38]{short}[r4] * 0x3 {short}
15832 ; iTemp11 [lr19:40]{short}[r3] = iTemp11 [lr19:40]{short}[r3] +
15837 ; iTemp15 [lr29:30]{short}[r1]
15856 ; iTemp17 [lr23:38]{int}[r7 r0]= iTemp17 [lr23:38]{int}[r7 r0]- 0x3 {short}
15903 ; _gint [lr0:0]{int} = _gint [lr0:0]{int} + iTemp17 [lr23:38]{int}[r7 r0]
15950 ; iTemp21 [lr21:38]{short}[r4] = iTemp21 [lr21:38]{short}[r4] + 0x1 {short}
15962 ; iTemp23 [lr22:38]{int}[r5 r6]= iTemp23 [lr22:38]{int}[r5 r6]- 0x1 {short}
15976 cjne r5,#0xff,00104$
15988 ; goto _forcond_0($4)
16000 ; _forbreak_0($7) :
16010 ; ret iTemp24 [lr40:41]{short}
16053 A few words about basic block successors, predecessors and dominators
16056 Successors are basic blocks
16057 \begin_inset LatexCommand \index{Basic blocks}
16061 that might execute after this basic block.
16063 Predecessors are basic blocks that might execute before reaching this basic
16066 Dominators are basic blocks that WILL execute before reaching this basic
16092 a) succList of [BB2] = [BB4], of [BB3] = [BB4], of [BB1] = [BB2,BB3]
16095 b) predList of [BB2] = [BB1], of [BB3] = [BB1], of [BB4] = [BB2,BB3]
16098 c) domVect of [BB4] = BB1 ...
16099 here we are not sure if BB2 or BB3 was executed but we are SURE that BB1
16107 \begin_inset LatexCommand \url{http://sdcc.sourceforge.net#Who}
16117 Thanks to all the other volunteer developers who have helped with coding,
16118 testing, web-page creation, distribution sets, etc.
16119 You know who you are :-)
16126 This document was initially written by Sandeep Dutta
16129 All product names mentioned herein may be trademarks
16130 \begin_inset LatexCommand \index{Trademarks}
16134 of their respective companies.
16141 To avoid confusion, the installation and building options for sdcc itself
16142 (chapter 2) are not part of the index.
16146 \begin_inset LatexCommand \printindex{}