1 #LyX 1.2 created this file. For more info see http://www.lyx.org/
15 \use_numerical_citations 0
16 \paperorientation portrait
19 \paragraph_separation indent
21 \quotes_language swedish
29 Please note: double dashed longoptions (e.g.
30 --version) need three dashes in this document to be visable in html and
34 SDCC Compiler User Guide
38 \begin_inset LatexCommand \tableofcontents{}
55 is a Freeware, retargettable, optimizing ANSI-C compiler by
59 designed for 8 bit Microprocessors.
60 The current version targets Intel MCS51 based Microprocessors(8051,8052,
61 etc), Zilog Z80 based MCUs, and the Dallas DS80C390 variant.
62 It can be retargetted for other microprocessors, support for PIC, AVR and
63 186 is under development.
64 The entire source code for the compiler is distributed under GPL.
65 SDCC uses ASXXXX & ASLINK, a Freeware, retargettable assembler & linker.
66 SDCC has extensive language extensions suitable for utilizing various microcont
67 rollers and underlying hardware effectively.
72 In addition to the MCU specific optimizations SDCC also does a host of standard
76 global sub expression elimination,
79 loop optimizations (loop invariant, strength reduction of induction variables
83 constant folding & propagation,
99 For the back-end SDCC uses a global register allocation scheme which should
100 be well suited for other 8 bit MCUs.
105 The peep hole optimizer uses a rule based substitution mechanism which is
111 Supported data-types are:
114 char (8 bits, 1 byte),
117 short and int (16 bits, 2 bytes),
120 long (32 bit, 4 bytes)
127 The compiler also allows
129 inline assembler code
131 to be embedded anywhere in a function.
132 In addition, routines developed in assembly can also be called.
136 SDCC also provides an option (--cyclomatic) to report the relative complexity
138 These functions can then be further optimized, or hand coded in assembly
144 SDCC also comes with a companion source level debugger SDCDB, the debugger
145 currently uses ucSim a freeware simulator for 8051 and other micro-controllers.
150 The latest version can be downloaded from
151 \begin_inset LatexCommand \url{http://sdcc.sourceforge.net/}
163 All packages used in this compiler system are
171 ; source code for all the sub-packages (pre-processor, assemblers, linkers
172 etc) is distributed with the package.
173 This documentation is maintained using a freeware word processor (LyX).
175 This program is free software; you can redistribute it and/or modify it
176 under the terms of the GNU General Public License as published by the Free
177 Software Foundation; either version 2, or (at your option) any later version.
178 This program is distributed in the hope that it will be useful, but WITHOUT
179 ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS
180 FOR A PARTICULAR PURPOSE.
181 See the GNU General Public License for more details.
182 You should have received a copy of the GNU General Public License along
183 with this program; if not, write to the Free Software Foundation, 59 Temple
184 Place - Suite 330, Boston, MA 02111-1307, USA.
185 In other words, you are welcome to use, share and improve this program.
186 You are forbidden to forbid anyone else to use, share and improve what
188 Help stamp out software-hoarding!
191 Typographic conventions
194 Throughout this manual, we will use the following convention.
195 Commands you have to type in are printed in
203 Code samples are printed in
208 Interesting items and new terms are printed in
213 Compatibility with previous versions
216 This version has numerous bug fixes compared with the previous version.
217 But we also introduced some incompatibilities with older versions.
218 Not just for the fun of it, but to make the compiler more stable, efficient
225 short is now equivalent to int (16 bits), it used to be equivalent to char
226 (8 bits) which is not ANSI compliant
229 the default directory for gcc-builds where include, library and documention
230 files are stored is now in /usr/local/share
233 char type parameters to vararg functions are casted to int unless explicitly
250 will push a as an int and as a char resp.
253 option ---regextend has been removed
256 option ---noregparms has been removed
259 option ---stack-after-data has been removed
264 <pending: more incompatibilities?>
270 What do you need before you start installation of SDCC? A computer, and
272 The preferred method of installation is to compile SDCC from source using
274 For Windows some pre-compiled binary distributions are available for your
276 You should have some experience with command line tools and compiler use.
282 The SDCC home page at
283 \begin_inset LatexCommand \url{http://sdcc.sourceforge.net/}
287 is a great place to find distribution sets.
288 You can also find links to the user mailing lists that offer help or discuss
289 SDCC with other SDCC users.
290 Web links to other SDCC related sites can also be found here.
291 This document can be found in the DOC directory of the source package as
293 Some of the other tools (simulator and assembler) included with SDCC contain
294 their own documentation and can be found in the source distribution.
295 If you want the latest unreleased software, the complete source package
296 is available directly by anonymous CVS on cvs.sdcc.sourceforge.net.
299 Wishes for the future
302 There are (and always will be) some things that could be done.
303 Here are some I can think of:
310 char KernelFunction3(char p) at 0x340;
316 If you can think of some more, please send them to the list.
322 <pending: And then of course a proper index-table
323 \begin_inset LatexCommand \index{index}
336 The install paths, search paths and other options are defined when running
338 The defaults can be overriden by:
340 \labelwidthstring 00.00.0000
342 ---prefix see tabel below
344 \labelwidthstring 00.00.0000
346 ---exec_prefix see tabel below
348 \labelwidthstring 00.00.0000
350 ---bindir see tabel below
352 \labelwidthstring 00.00.0000
354 ---datadir see tabel below
356 \labelwidthstring 00.00.0000
358 docdir environment variable, see tabel below
360 \labelwidthstring 00.00.0000
362 include_dir_suffix environment variable, see tabel below
364 \labelwidthstring 00.00.0000
366 lib_dir_suffix environment variable, see tabel below
368 \labelwidthstring 00.00.0000
370 sdccconf_h_dir_separator environment variable, either / or
375 This character will only be used in sdccconf.h; don't forget it's a C-header,
376 therefore a double-backslash is needed there.
378 \labelwidthstring 00.00.0000
380 ---disable-mcs51-port Excludes the Intel mcs51 port
382 \labelwidthstring 00.00.0000
384 ---disable-gbz80-port Excludes the Gameboy gbz80 port
386 \labelwidthstring 00.00.0000
388 ---disable-z80-port Excludes the z80 port
390 \labelwidthstring 00.00.0000
392 ---disable-avr-port Excludes the AVR port
394 \labelwidthstring 00.00.0000
396 ---disable-ds390-port Excludes the DS390 port
398 \labelwidthstring 00.00.0000
400 ---disable-pic-port Excludes the PIC port
402 \labelwidthstring 00.00.0000
404 ---disable-xa51-port Excludes the XA51 port
406 \labelwidthstring 00.00.0000
408 ---disable-ucsim Disables configuring and building of ucsim
410 \labelwidthstring 00.00.0000
412 ---disable-device-lib-build Disables automatically building device libraries
414 \labelwidthstring 00.00.0000
416 ---disable-packihx Disables building packihx
418 \labelwidthstring 00.00.0000
420 ---enable-libgc Use the Bohem memory allocator.
421 Lower runtime footprint.
424 Furthermore the environment variables CC, CFLAGS, ...
425 the tools and their arguments can be influenced.
426 Please see `configure ---help` and the man/info pages of `configure` for
431 The names of the standard libraries STD_LIB, STD_INT_LIB, STD_LONG_LIB,
432 STD_FP_LIB, STD_DS390_LIB, STD_XA51_LIB and the environment variables SDCC_DIR_
433 NAME, SDCC_INCLUDE_NAME, SDCC_LIB_NAME are defined by `configure` too.
434 At the moment it's not possible to change the default settings (it was
435 simply never required.
439 These configure options are compiled into the binaries, and can only be
440 changed by rerunning 'configure' and recompiling SDCC.
441 The configure options are written in
445 to distinguish them from run time environment variables (see section search
451 \begin_inset Quotes sld
455 \begin_inset Quotes srd
458 are used by the SDCC team to build the official Win32 binaries.
459 The SDCC team uses Mingw32 to build the official Windows binaries, because
466 a gcc compiler and last but not least
469 the binaries can be built by cross compiling on Sourceforge's compile farm.
472 See the examples, how to pass the Win32 settings to 'configure'.
473 The other Win32 builds using Borland, VC or whatever don't use 'configure',
474 but a header file sdcc_vc_in.h is the same as sdccconf.h built by 'configure'
485 <lyxtabular version="3" rows="8" columns="3">
487 <column alignment="left" valignment="top" leftline="true" width="0in">
488 <column alignment="left" valignment="top" leftline="true" width="0in">
489 <column alignment="left" valignment="top" leftline="true" rightline="true" width="0in">
490 <row topline="true" bottomline="true">
491 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
499 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
507 <cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
517 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
527 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
535 <cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
547 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
557 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
567 <cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
579 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
589 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
601 <cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
617 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
627 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
639 <cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
651 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
661 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
673 <cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
689 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
699 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
707 <cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
716 <row topline="true" bottomline="true">
717 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
727 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
735 <cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
754 'configure' also computes relative paths.
755 This is needed for full relocatability of a binary package and to complete
756 search paths (see section search paths below):
762 <lyxtabular version="3" rows="4" columns="3">
764 <column alignment="left" valignment="top" leftline="true" width="0in">
765 <column alignment="left" valignment="top" leftline="true" width="0in">
766 <column alignment="left" valignment="top" leftline="true" rightline="true" width="0in">
767 <row topline="true" bottomline="true">
768 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
776 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
784 <cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
793 <row topline="true" bottomline="true">
794 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
804 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
812 <cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
823 <row bottomline="true">
824 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
834 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
842 <cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
851 <row bottomline="true">
852 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
862 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
870 <cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
892 ./configure ---prefix=
893 \begin_inset Quotes srd
897 \begin_inset Quotes srd
901 \begin_inset Quotes srd
905 \begin_inset Quotes srd
911 ./configure ---disable-avr-port ---disable-xa51-port
914 To crosscompile on linux for Mingw32 (see also 'sdcc/support/scripts/sdcc_mingw3
924 \begin_inset Quotes srd
928 \begin_inset Quotes srd
932 \begin_inset Quotes srd
936 \begin_inset Quotes srd
945 \begin_inset Quotes srd
948 i586-mingw32msvc-ranlib
949 \begin_inset Quotes srd
958 \begin_inset Quotes srd
961 i586-mingw32msvc-strip
962 \begin_inset Quotes srd
971 \begin_inset Quotes srd
975 \begin_inset Quotes srd
984 \begin_inset Quotes srd
988 \begin_inset Quotes srd
997 \begin_inset Quotes srd
1001 \begin_inset Quotes srd
1010 \begin_inset Quotes srd
1014 \begin_inset Quotes srd
1023 \begin_inset Quotes srd
1027 \begin_inset Quotes srd
1035 sdccconf_h_dir_separator=
1036 \begin_inset Quotes srd
1048 \begin_inset Quotes srd
1056 ---disable-device-lib-build
1066 ---host=i586-mingw32msvc ---build=unknown-unknown-linux-gnu
1070 \begin_inset Quotes sld
1074 \begin_inset Quotes srd
1077 compile on Cygwin for Mingw32(see also sdcc/support/scripts/sdcc_cygwin_mingw32)
1087 \begin_inset Quotes srd
1091 \begin_inset Quotes srd
1100 \begin_inset Quotes srd
1104 \begin_inset Quotes srd
1113 \begin_inset Quotes srd
1117 \begin_inset Quotes srd
1126 \begin_inset Quotes srd
1130 \begin_inset Quotes srd
1139 \begin_inset Quotes srd
1143 \begin_inset Quotes srd
1152 \begin_inset Quotes srd
1156 \begin_inset Quotes srd
1165 \begin_inset Quotes srd
1169 \begin_inset Quotes srd
1177 sdccconf_h_dir_separator=
1178 \begin_inset Quotes srd
1190 \begin_inset Quotes srd
1201 'configure' is quite slow on Cygwin (at least on windows before Win2000/XP).
1202 The option '--C' turns on caching, which gives a little bit extra speed.
1203 However if options are changed, it can be necessary to delete the config.cache
1211 Binary files (preprocessor, assembler and linker)
1215 \begin_inset Tabular
1216 <lyxtabular version="3" rows="2" columns="3">
1218 <column alignment="left" valignment="top" leftline="true" width="0in">
1219 <column alignment="left" valignment="top" leftline="true" width="0in">
1220 <column alignment="left" valignment="top" leftline="true" rightline="true" width="0in">
1221 <row topline="true" bottomline="true">
1222 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
1230 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
1238 <cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
1247 <row topline="true" bottomline="true">
1248 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
1258 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
1266 <cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
1292 \begin_inset Tabular
1293 <lyxtabular version="3" rows="2" columns="3">
1295 <column alignment="block" valignment="top" leftline="true" width="1.6in">
1296 <column alignment="left" valignment="top" leftline="true" width="0in">
1297 <column alignment="center" valignment="top" leftline="true" rightline="true" width="0in">
1298 <row topline="true" bottomline="true">
1299 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
1307 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
1315 <cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
1324 <row topline="true" bottomline="true">
1325 <cell alignment="left" valignment="top" topline="true" leftline="true" usebox="none">
1337 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
1342 /usr/local/share/sdcc/include
1345 <cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
1371 is auto-appended by the compiler, e.g.
1372 small, large, z80, ds390 etc.)
1376 \begin_inset Tabular
1377 <lyxtabular version="3" rows="2" columns="3">
1379 <column alignment="left" valignment="top" leftline="true" width="0in">
1380 <column alignment="left" valignment="top" leftline="true" width="0in">
1381 <column alignment="left" valignment="top" leftline="true" rightline="true" width="0in">
1382 <row topline="true" bottomline="true">
1383 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
1391 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
1399 <cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
1408 <row topline="true" bottomline="true">
1409 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
1416 $DATADIR/$LIB_DIR_SUFFIX
1419 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
1424 /usr/local/share/sdcc/lib
1427 <cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
1453 \begin_inset Tabular
1454 <lyxtabular version="3" rows="2" columns="3">
1456 <column alignment="left" valignment="top" leftline="true" width="0in">
1457 <column alignment="left" valignment="top" leftline="true" width="0in">
1458 <column alignment="left" valignment="top" leftline="true" rightline="true" width="0in">
1459 <row topline="true" bottomline="true">
1460 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
1468 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
1476 <cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
1485 <row topline="true" bottomline="true">
1486 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
1496 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
1501 /usr/local/share/sdcc/doc
1504 <cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
1525 The install paths can still be changed during `make install` with e.g.:
1528 make install prefix=$(HOME)/local/sdcc
1531 Of course this doesn't change the search paths compiled into the binaries.
1537 Some search paths or parts of them are determined by configure variables
1542 , see section above).
1543 Further search paths are determined by environment variables during runtime.
1546 The paths searched when running the compiler are as follows (the first catch
1552 Binary files (preprocessor, assembler and linker)
1555 \begin_inset Tabular
1556 <lyxtabular version="3" rows="4" columns="3">
1558 <column alignment="left" valignment="top" leftline="true" width="0in">
1559 <column alignment="left" valignment="top" leftline="true" width="0in">
1560 <column alignment="left" valignment="top" leftline="true" rightline="true" width="0in">
1561 <row topline="true" bottomline="true">
1562 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
1570 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
1578 <cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
1587 <row topline="true">
1588 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
1598 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
1606 <cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
1617 <row topline="true">
1618 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
1623 Path of argv[0] (if available)
1626 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
1634 <cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
1643 <row topline="true" bottomline="true">
1644 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
1652 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
1660 <cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
1681 \begin_inset Tabular
1682 <lyxtabular version="3" rows="6" columns="3">
1684 <column alignment="block" valignment="top" leftline="true" width="1.5in">
1685 <column alignment="block" valignment="top" leftline="true" width="1.5in">
1686 <column alignment="left" valignment="top" leftline="true" rightline="true" width="0in">
1687 <row topline="true" bottomline="true">
1688 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
1696 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
1704 <cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
1713 <row topline="true">
1714 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
1722 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
1730 <cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
1739 <row topline="true">
1740 <cell alignment="left" valignment="top" topline="true" leftline="true" usebox="none">
1748 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
1756 <cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
1765 <row topline="true">
1766 <cell alignment="left" valignment="top" topline="true" leftline="true" usebox="none">
1780 <cell alignment="left" valignment="top" topline="true" leftline="true" usebox="none">
1792 <cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
1803 <row topline="true">
1804 <cell alignment="left" valignment="top" topline="true" leftline="true" usebox="none">
1822 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
1872 <cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
1885 <row topline="true" bottomline="true">
1886 <cell alignment="left" valignment="top" topline="true" leftline="true" usebox="none">
1902 <cell alignment="left" valignment="top" topline="true" leftline="true" usebox="none">
1907 /usr/local/share/sdcc/
1912 <cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
1929 The option ---nostdinc disables the last two search paths.
1936 With the exception of
1937 \begin_inset Quotes sld
1941 \begin_inset Quotes srd
1948 is auto-appended by the compiler (e.g.
1949 small, large, z80, ds390 etc.).
1953 \begin_inset Tabular
1954 <lyxtabular version="3" rows="6" columns="3">
1956 <column alignment="block" valignment="top" leftline="true" width="1.7in">
1957 <column alignment="left" valignment="top" leftline="true" width="1.2in">
1958 <column alignment="block" valignment="top" leftline="true" rightline="true" width="1.2in">
1959 <row topline="true" bottomline="true">
1960 <cell alignment="left" valignment="top" topline="true" leftline="true" usebox="none">
1968 <cell alignment="left" valignment="top" topline="true" leftline="true" usebox="none">
1976 <cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
1985 <row topline="true">
1986 <cell alignment="left" valignment="top" topline="true" leftline="true" usebox="none">
1994 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
2002 <cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
2011 <row topline="true">
2012 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
2024 <cell alignment="left" valignment="top" topline="true" leftline="true" usebox="none">
2036 <cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
2051 <row topline="true">
2052 <cell alignment="left" valignment="top" topline="true" leftline="true" usebox="none">
2063 $LIB_DIR_SUFFIX/<model>
2066 <cell alignment="left" valignment="top" topline="true" leftline="true" usebox="none">
2080 <cell alignment="left" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
2097 <row topline="true">
2098 <cell alignment="left" valignment="top" topline="true" leftline="true" usebox="none">
2113 $LIB_DIR_SUFFIX/<model>
2116 <cell alignment="left" valignment="top" topline="true" leftline="true" usebox="none">
2169 <cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
2225 <row topline="true" bottomline="true">
2226 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
2235 $LIB_DIR_SUFFIX/<model>
2238 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
2243 /usr/local/share/sdcc/
2250 <cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
2266 Don't delete any of the stray spaces in the table above without checking
2267 the HTML output (last line)!
2273 The option ---nostdlib disables the last two search paths.
2277 \layout Subsubsection
2279 Building SDCC on Linux
2284 Download the source package
2286 either from the SDCC CVS repository or from the
2287 \begin_inset LatexCommand \url[nightly snapshots]{http://sdcc.sourceforge.net/snap.php}
2293 , it will be named something like sdcc
2306 Bring up a command line terminal, such as xterm.
2311 Unpack the file using a command like:
2314 "tar -xzf sdcc.src.tar.gz
2319 , this will create a sub-directory called sdcc with all of the sources.
2322 Change directory into the main SDCC directory, for example type:
2339 This configures the package for compilation on your system.
2355 All of the source packages will compile, this can take a while.
2371 This copies the binary executables, the include files, the libraries and
2372 the documentation to the install directories.
2373 \layout Subsubsection
2375 Building SDCC on OSX 2.x
2378 Follow the instruction for Linux.
2382 On OSX 2.x it was reported, that the default gcc (version 3.1 20020420 (prerelease
2383 )) fails to compile SDCC.
2384 Fortunately there's also gcc 2.9.x installed, which works fine.
2385 This compiler can be selected by running 'configure' with:
2388 ./configure CC=gcc2 CXX=g++2
2389 \layout Subsubsection
2391 Crosscompiling SDCC on Linux for Windows
2394 With the Mingw32 gcc crosscompiler it's easy to compile SDCC for Win32.
2395 See section 'Configure Options'.
2396 \layout Subsubsection
2398 Building SDCC on Windows
2401 With the exception of Cygwin the SDCC binaries uCsim and sdcdb can't be
2403 They use Unix-sockets, which are not available on Win32.
2404 \layout Subsubsection
2406 Windows Install Using a Binary Package
2409 Download the binary package and unpack it using your favorite unpacking
2410 tool (gunzip, WinZip, etc).
2411 This should unpack to a group of sub-directories.
2412 An example directory structure after unpacking the mingw32 package is:
2417 bin for the executables, c:
2425 lib for the include and libraries.
2428 Adjust your environment variable PATH to include the location of the bin
2429 directory or start sdcc using the full path.
2430 \layout Subsubsection
2432 Building SDCC using Cygwin and Mingw32
2435 For building and installing a Cygwin executable follow the instructions
2441 \begin_inset Quotes sld
2445 \begin_inset Quotes srd
2448 Win32-binary can be built, which will not need the Cygwin-DLL.
2449 For the necessary 'configure' options see section 'configure options' or
2450 the script 'sdcc/support/scripts/sdcc_cygwinmingw32'.
2454 In order to install Cygwin on Windows download setup.exe from
2455 \begin_inset LatexCommand \url[www.cygwin.com]{http://www.cygwin.com/}
2461 \begin_inset Quotes sld
2464 default text file type
2465 \begin_inset Quotes srd
2469 \begin_inset Quotes sld
2473 \begin_inset Quotes srd
2476 and download/install at least the following packages.
2477 Some packages are selected by default, others will be automatically selected
2478 because of dependencies with the manually selected packages.
2479 Never deselect these packages!
2488 gcc ; version 3.x is fine, no need to use the old 2.9x
2491 binutils ; selected with gcc
2497 rxvt ; a nice console, which makes life much easier under windoze (see below)
2500 man ; not really needed for building SDCC, but you'll miss it sooner or
2504 less ; not really needed for building SDCC, but you'll miss it sooner or
2508 cvs ; only if you use CVS access
2511 If you want to develop something you'll need:
2514 python ; for the regression tests
2517 gdb ; the gnu debugger, together with the nice GUI
2518 \begin_inset Quotes sld
2522 \begin_inset Quotes srd
2528 openssh ; to access the CF or commit changes
2531 autoconf and autoconf-devel ; if you want to fight with 'configure', don't
2532 use autoconf-stable!
2535 rxvt is a nice console with history.
2536 Replace in your cygwin.bat the line
2545 rxvt -sl 1000 -fn "Lucida Console-12" -sr -cr red
2548 -bg black -fg white -geometry 100x65 -e bash --login
2551 Text selected with the mouse is automatically copied to the clipboard, pasting
2552 works with shift-insert.
2556 The other good tip is to make sure you have no //c/-style paths anywhere,
2557 use /cygdrive/c/ instead.
2558 Using // invokes a network lookup which is very slow.
2560 \begin_inset Quotes sld
2564 \begin_inset Quotes srd
2567 is too long, you can change it with e.g.
2573 SDCC sources use the unix line ending LF.
2574 Life is much easier, if you store the source tree on a drive, which is
2575 mount in binary mode.
2576 And use an editor which can handle LF-only line endings.
2577 Make sure not to commit files with windows line endings.
2578 \layout Subsubsection
2580 Windows Install Using Microsoft Visual C++ 6.0/NET
2585 Download the source package
2587 either from the SDCC CVS repository or from the
2588 \begin_inset LatexCommand \url[nightly snapshots]{http://sdcc.sourceforge.net/snap.php}
2594 , it will be named something like sdcc
2601 SDCC is distributed with all the projects, workspaces, and files you need
2602 to build it using Visual C++ 6.0/NET.
2603 The workspace name is 'sdcc.dsw'.
2604 Please note that as it is now, all the executables are created in a folder
2608 Once built you need to copy the executables from sdcc
2612 bin before runnng SDCC.
2617 In order to build SDCC with Visual C++ 6.0/NET you need win32 executables
2618 of bison.exe, flex.exe, and gawk.exe.
2619 One good place to get them is
2620 \begin_inset LatexCommand \url[here]{http://unxutils.sourceforge.net}
2628 Download the file UnxUtils.zip.
2629 Now you have to install the utilities and setup Visual C++ so it can locate
2630 the required programs.
2631 Here there are two alternatives (choose one!):
2638 a) Extract UnxUtils.zip to your C:
2640 hard disk PRESERVING the original paths, otherwise bison won't work.
2641 (If you are using WinZip make certain that 'Use folder names' is selected)
2645 b) In the Visual C++ IDE click Tools, Options, select the Directory tab,
2646 in 'Show directories for:' select 'Executable files', and in the directories
2647 window add a new path: 'C:
2657 (As a side effect, you get a bunch of Unix utilities that could be useful,
2658 such as diff and patch.)
2665 This one avoids extracting a bunch of files you may not use, but requires
2670 a) Create a directory were to put the tools needed, or use a directory already
2678 b) Extract 'bison.exe', 'bison.hairy', 'bison.simple', 'flex.exe', and gawk.exe
2679 to such directory WITHOUT preserving the original paths.
2680 (If you are using WinZip make certain that 'Use folder names' is not selected)
2684 c) Rename bison.exe to '_bison.exe'.
2688 d) Create a batch file 'bison.bat' in 'C:
2692 ' and add these lines:
2712 _bison %1 %2 %3 %4 %5 %6 %7 %8 %9
2716 Steps 'c' and 'd' are needed because bison requires by default that the
2717 files 'bison.simple' and 'bison.hairy' reside in some weird Unix directory,
2718 '/usr/local/share/' I think.
2719 So it is necessary to tell bison where those files are located if they
2720 are not in such directory.
2721 That is the function of the environment variables BISON_SIMPLE and BISON_HAIRY.
2725 e) In the Visual C++ IDE click Tools, Options, select the Directory tab,
2726 in 'Show directories for:' select 'Executable files', and in the directories
2727 window add a new path: 'c:
2730 Note that you can use any other path instead of 'c:
2732 util', even the path where the Visual C++ tools are, probably: 'C:
2736 Microsoft Visual Studio
2741 So you don't have to execute step 'e' :)
2745 Open 'sdcc.dsw' in Visual Studio, click 'build all', when it finishes copy
2746 the executables from sdcc
2750 bin, and you can compile using sdcc.
2751 \layout Subsubsection
2753 Windows Install Using Borland
2756 From the sdcc directory, run the command "make -f Makefile.bcc".
2757 This should regenerate all the .exe files in the bin directory except for
2758 sdcdb.exe (which currently doesn't build under Borland C++).
2761 If you modify any source files and need to rebuild, be aware that the dependanci
2762 es may not be correctly calculated.
2763 The safest option is to delete all .obj files and run the build again.
2764 From a Cygwin BASH prompt, this can easily be done with the commmand:
2774 ( -name '*.obj' -o -name '*.lib' -o -name '*.rul'
2776 ) -print -exec rm {}
2785 or on Windows NT/2000/XP from the command prompt with the commmand:
2792 del /s *.obj *.lib *.rul
2795 from the sdcc directory.
2798 Building the Documentation
2805 Testing out the SDCC Compiler
2808 The first thing you should do after installing your SDCC compiler is to
2816 at the prompt, and the program should run and tell you the version.
2817 If it doesn't run, or gives a message about not finding sdcc program, then
2818 you need to check over your installation.
2819 Make sure that the sdcc bin directory is in your executable search path
2820 defined by the PATH environment setting (see the Trouble-shooting section
2822 Make sure that the sdcc program is in the bin folder, if not perhaps something
2823 did not install correctly.
2831 is commonly installed as described in section
2832 \begin_inset Quotes sld
2835 Install and search paths
2836 \begin_inset Quotes srd
2845 Make sure the compiler works on a very simple example.
2846 Type in the following test.c program using your favorite
2881 Compile this using the following command:
2890 If all goes well, the compiler will generate a test.asm and test.rel file.
2891 Congratulations, you've just compiled your first program with SDCC.
2892 We used the -c option to tell SDCC not to link the generated code, just
2893 to keep things simple for this step.
2901 The next step is to try it with the linker.
2911 If all goes well the compiler will link with the libraries and produce
2912 a test.ihx output file.
2917 (no test.ihx, and the linker generates warnings), then the problem is most
2918 likely that sdcc cannot find the
2922 usr/local/share/sdcc/lib directory
2926 (see the Install trouble-shooting section for suggestions).
2934 The final test is to ensure sdcc can use the
2938 header files and libraries.
2939 Edit test.c and change it to the following:
2959 strcpy(str1, "testing");
2968 Compile this by typing
2975 This should generate a test.ihx output file, and it should give no warnings
2976 such as not finding the string.h file.
2977 If it cannot find the string.h file, then the problem is that sdcc cannot
2978 find the /usr/local/share/sdcc/include directory
2982 (see the Install trouble-shooting section for suggestions).
2985 Install Trouble-shooting
2986 \layout Subsubsection
2988 SDCC does not build correctly.
2991 A thing to try is starting from scratch by unpacking the .tgz source package
2992 again in an empty directory.
3000 ./configure 2>&1 | tee configure.log
3014 make 2>&1 | tee make.log
3021 If anything goes wrong, you can review the log files to locate the problem.
3022 Or a relevant part of this can be attached to an email that could be helpful
3023 when requesting help from the mailing list.
3024 \layout Subsubsection
3027 \begin_inset Quotes sld
3031 \begin_inset Quotes srd
3038 \begin_inset Quotes sld
3042 \begin_inset Quotes srd
3045 command is a script that analyzes your system and performs some configuration
3046 to ensure the source package compiles on your system.
3047 It will take a few minutes to run, and will compile a few tests to determine
3048 what compiler features are installed.
3049 \layout Subsubsection
3052 \begin_inset Quotes sld
3056 \begin_inset Quotes srd
3062 This runs the GNU make tool, which automatically compiles all the source
3063 packages into the final installed binary executables.
3064 \layout Subsubsection
3067 \begin_inset Quotes sld
3071 \begin_inset Quotes erd
3077 This will install the compiler, other executables libraries and include
3078 files in to the appropriate directories.
3080 \begin_inset Quotes sld
3083 Install and Search PATHS
3084 \begin_inset Quotes srd
3089 On most systems you will need super-user privilages to do this.
3095 SDCC is not just a compiler, but a collection of tools by various developers.
3096 These include linkers, assemblers, simulators and other components.
3097 Here is a summary of some of the components.
3098 Note that the included simulator and assembler have separate documentation
3099 which you can find in the source package in their respective directories.
3100 As SDCC grows to include support for other processors, other packages from
3101 various developers are included and may have their own sets of documentation.
3105 You might want to look at the files which are installed in <installdir>.
3106 At the time of this writing, we find the following programs for gcc-builds:
3110 In <installdir>/bin:
3113 sdcc - The compiler.
3116 sdcpp - The C preprocessor.
3119 asx8051 - The assembler for 8051 type processors.
3126 as-gbz80 - The Z80 and GameBoy Z80 assemblers.
3129 aslink -The linker for 8051 type processors.
3136 link-gbz80 - The Z80 and GameBoy Z80 linkers.
3139 s51 - The ucSim 8051 simulator.
3142 sdcdb - The source debugger.
3145 packihx - A tool to pack (compress) Intel hex files.
3148 In <installdir>/share/sdcc/include
3154 In <installdir>/share/sdcc/lib
3157 the subdirs src and small, large, z80, gbz80 and ds390 with the precompiled
3161 In <installdir>/share/sdcc/doc
3167 As development for other processors proceeds, this list will expand to include
3168 executables to support processors like AVR, PIC, etc.
3169 \layout Subsubsection
3174 This is the actual compiler, it in turn uses the c-preprocessor and invokes
3175 the assembler and linkage editor.
3176 \layout Subsubsection
3178 sdcpp - The C-Preprocessor
3181 The preprocessor is a modified version of the GNU preprocessor.
3182 The C preprocessor is used to pull in #include sources, process #ifdef
3183 statements, #defines and so on.
3184 \layout Subsubsection
3186 asx8051, as-z80, as-gbz80, aslink, link-z80, link-gbz80 - The Assemblers
3190 This is retargettable assembler & linkage editor, it was developed by Alan
3192 John Hartman created the version for 8051, and I (Sandeep) have made some
3193 enhancements and bug fixes for it to work properly with the SDCC.
3194 \layout Subsubsection
3199 S51 is a freeware, opensource simulator developed by Daniel Drotos (
3200 \begin_inset LatexCommand \url{mailto:drdani@mazsola.iit.uni-miskolc.hu}
3205 The simulator is built as part of the build process.
3206 For more information visit Daniel's website at:
3207 \begin_inset LatexCommand \url{http://mazsola.iit.uni-miskolc.hu/~drdani/embedded/s51}
3212 It currently support the core mcs51, the Dallas DS80C390 and the Philips
3214 \layout Subsubsection
3216 sdcdb - Source Level Debugger
3222 <todo: is this thing still alive?>
3229 Sdcdb is the companion source level debugger.
3230 The current version of the debugger uses Daniel's Simulator S51, but can
3231 be easily changed to use other simulators.
3238 \layout Subsubsection
3240 Single Source File Projects
3243 For single source file 8051 projects the process is very simple.
3244 Compile your programs with the following command
3247 "sdcc sourcefile.c".
3251 This will compile, assemble and link your source file.
3252 Output files are as follows
3256 sourcefile.asm - Assembler source file created by the compiler
3258 sourcefile.lst - Assembler listing file created by the Assembler
3260 sourcefile.rst - Assembler listing file updated with linkedit information,
3261 created by linkage editor
3263 sourcefile.sym - symbol listing for the sourcefile, created by the assembler
3265 sourcefile.rel - Object file created by the assembler, input to Linkage editor
3267 sourcefile.map - The memory map for the load module, created by the Linker
3269 sourcefile.mem - A file with a summary of the memory ussage
3271 sourcefile.ihx - The load module in Intel hex format (you can select the
3272 Motorola S19 format with ---out-fmt-s19)
3274 sourcefile.adb - An intermediate file containing debug information needed
3275 to create the .cdb file (with ---debug)
3277 sourcefile.cdb - An optional file (with ---debug) containing debug information
3279 sourcefile. - (no extension) An optional AOMF51 file containing debug
3280 information (with ---debug)
3282 sourcefile.dump* - Dump file to debug the compiler it self (with ---dumpall)
3284 \begin_inset Quotes sld
3287 Anatomy of the compiler
3288 \begin_inset Quotes srd
3292 \layout Subsubsection
3294 Projects with Multiple Source Files
3297 SDCC can compile only ONE file at a time.
3298 Let us for example assume that you have a project containing the following
3303 foo1.c (contains some functions)
3305 foo2.c (contains some more functions)
3307 foomain.c (contains more functions and the function main)
3315 The first two files will need to be compiled separately with the commands:
3347 Then compile the source file containing the
3351 function and link the files together with the following command:
3359 foomain.c\SpecialChar ~
3360 foo1.rel\SpecialChar ~
3372 can be separately compiled as well:
3383 sdcc foomain.rel foo1.rel foo2.rel
3390 The file containing the
3405 file specified in the command line, since the linkage editor processes
3406 file in the order they are presented to it.
3407 \layout Subsubsection
3409 Projects with Additional Libraries
3412 Some reusable routines may be compiled into a library, see the documentation
3413 for the assembler and linkage editor (which are in <installdir>/share/sdcc/doc)
3419 Libraries created in this manner can be included in the command line.
3420 Make sure you include the -L <library-path> option to tell the linker where
3421 to look for these files if they are not in the current directory.
3422 Here is an example, assuming you have the source file
3434 (if that is not the same as your current project):
3441 sdcc foomain.c foolib.lib -L mylib
3452 must be an absolute path name.
3456 The most efficient way to use libraries is to keep seperate modules in seperate
3458 The lib file now should name all the modules.rel files.
3459 For an example see the standard library file
3463 in the directory <installdir>/share/lib/small.
3466 Command Line Options
3467 \layout Subsubsection
3469 Processor Selection Options
3471 \labelwidthstring 00.00.0000
3477 Generate code for the MCS51 (8051) family of processors.
3478 This is the default processor target.
3480 \labelwidthstring 00.00.0000
3486 Generate code for the DS80C390 processor.
3488 \labelwidthstring 00.00.0000
3494 Generate code for the Z80 family of processors.
3496 \labelwidthstring 00.00.0000
3502 Generate code for the GameBoy Z80 processor.
3504 \labelwidthstring 00.00.0000
3510 Generate code for the Atmel AVR processor (In development, not complete).
3512 \labelwidthstring 00.00.0000
3518 Generate code for the PIC 14-bit processors (In development, not complete).
3520 \labelwidthstring 00.00.0000
3526 Generate code for the Toshiba TLCS-900H processor (In development, not
3529 \labelwidthstring 00.00.0000
3535 Generate code for the Philips XA51 processor (In development, not complete).
3536 \layout Subsubsection
3538 Preprocessor Options
3540 \labelwidthstring 00.00.0000
3546 The additional location where the pre processor will look for <..h> or
3547 \begin_inset Quotes eld
3551 \begin_inset Quotes erd
3556 \labelwidthstring 00.00.0000
3562 Command line definition of macros.
3563 Passed to the pre processor.
3565 \labelwidthstring 00.00.0000
3571 Tell the preprocessor to output a rule suitable for make describing the
3572 dependencies of each object file.
3573 For each source file, the preprocessor outputs one make-rule whose target
3574 is the object file name for that source file and whose dependencies are
3575 all the files `#include'd in it.
3576 This rule may be a single line or may be continued with `
3578 '-newline if it is long.
3579 The list of rules is printed on standard output instead of the preprocessed
3583 \labelwidthstring 00.00.0000
3589 Tell the preprocessor not to discard comments.
3590 Used with the `-E' option.
3592 \labelwidthstring 00.00.0000
3603 Like `-M' but the output mentions only the user header files included with
3605 \begin_inset Quotes eld
3609 System header files included with `#include <file>' are omitted.
3611 \labelwidthstring 00.00.0000
3617 Assert the answer answer for question, in case it is tested with a preprocessor
3618 conditional such as `#if #question(answer)'.
3619 `-A-' disables the standard assertions that normally describe the target
3622 \labelwidthstring 00.00.0000
3628 (answer) Assert the answer answer for question, in case it is tested with
3629 a preprocessor conditional such as `#if #question(answer)'.
3630 `-A-' disables the standard assertions that normally describe the target
3633 \labelwidthstring 00.00.0000
3639 Undefine macro macro.
3640 `-U' options are evaluated after all `-D' options, but before any `-include'
3641 and `-imacros' options.
3643 \labelwidthstring 00.00.0000
3649 Tell the preprocessor to output only a list of the macro definitions that
3650 are in effect at the end of preprocessing.
3651 Used with the `-E' option.
3653 \labelwidthstring 00.00.0000
3659 Tell the preprocessor to pass all macro definitions into the output, in
3660 their proper sequence in the rest of the output.
3662 \labelwidthstring 00.00.0000
3673 Like `-dD' except that the macro arguments and contents are omitted.
3674 Only `#define name' is included in the output.
3675 \layout Subsubsection
3679 \labelwidthstring 00.00.0000
3689 <absolute path to additional libraries> This option is passed to the linkage
3690 editor's additional libraries search path.
3691 The path name must be absolute.
3692 Additional library files may be specified in the command line.
3693 See section Compiling programs for more details.
3695 \labelwidthstring 00.00.0000
3701 <Value> The start location of the external ram, default value is 0.
3702 The value entered can be in Hexadecimal or Decimal format, e.g.: ---xram-loc
3703 0x8000 or ---xram-loc 32768.
3705 \labelwidthstring 00.00.0000
3711 <Value> The start location of the code segment, default value 0.
3712 Note when this option is used the interrupt vector table is also relocated
3713 to the given address.
3714 The value entered can be in Hexadecimal or Decimal format, e.g.: ---code-loc
3715 0x8000 or ---code-loc 32768.
3717 \labelwidthstring 00.00.0000
3723 <Value> By default the stack is placed after the data segment.
3724 Using this option the stack can be placed anywhere in the internal memory
3726 The value entered can be in Hexadecimal or Decimal format, e.g.
3727 ---stack-loc 0x20 or ---stack-loc 32.
3728 Since the sp register is incremented before a push or call, the initial
3729 sp will be set to one byte prior the provided value.
3730 The provided value should not overlap any other memory areas such as used
3731 register banks or the data segment and with enough space for the current
3734 \labelwidthstring 00.00.0000
3740 <Value> The start location of the internal ram data segment.
3741 The value entered can be in Hexadecimal or Decimal format, eg.
3742 ---data-loc 0x20 or ---data-loc 32.
3743 (By default, the start location of the internal ram data segment is set
3744 as low as possible in memory, taking into account the used register banks
3745 and the bit segment at address 0x20.
3746 For example if register banks 0 and 1 are used without bit variables, the
3747 data segment will be set, if ---data-loc is not used, to location 0x10.)
3749 \labelwidthstring 00.00.0000
3755 <Value> The start location of the indirectly addressable internal ram, default
3757 The value entered can be in Hexadecimal or Decimal format, eg.
3758 ---idata-loc 0x88 or ---idata-loc 136.
3760 \labelwidthstring 00.00.0000
3769 The linker output (final object code) is in Intel Hex format.
3770 (This is the default option).
3772 \labelwidthstring 00.00.0000
3781 The linker output (final object code) is in Motorola S19 format.
3782 \layout Subsubsection
3786 \labelwidthstring 00.00.0000
3792 Generate code for Large model programs see section Memory Models for more
3794 If this option is used all source files in the project should be compiled
3796 In addition the standard library routines are compiled with small model,
3797 they will need to be recompiled.
3799 \labelwidthstring 00.00.0000
3810 Generate code for Small Model programs see section Memory Models for more
3812 This is the default model.
3813 \layout Subsubsection
3817 \labelwidthstring 00.00.0000
3828 Generate 24-bit flat mode code.
3829 This is the one and only that the ds390 code generator supports right now
3830 and is default when using
3835 See section Memory Models for more details.
3837 \labelwidthstring 00.00.0000
3843 Generate code for the 10 bit stack mode of the Dallas DS80C390 part.
3844 This is the one and only that the ds390 code generator supports right now
3845 and is default when using
3850 In this mode, the stack is located in the lower 1K of the internal RAM,
3851 which is mapped to 0x400000.
3852 Note that the support is incomplete, since it still uses a single byte
3853 as the stack pointer.
3854 This means that only the lower 256 bytes of the potential 1K stack space
3855 will actually be used.
3856 However, this does allow you to reclaim the precious 256 bytes of low RAM
3857 for use for the DATA and IDATA segments.
3858 The compiler will not generate any code to put the processor into 10 bit
3860 It is important to ensure that the processor is in this mode before calling
3861 any re-entrant functions compiled with this option.
3862 In principle, this should work with the
3866 option, but that has not been tested.
3867 It is incompatible with the
3872 It also only makes sense if the processor is in 24 bit contiguous addressing
3875 ---model-flat24 option
3878 \layout Subsubsection
3880 Optimization Options
3882 \labelwidthstring 00.00.0000
3888 Will not do global subexpression elimination, this option may be used when
3889 the compiler creates undesirably large stack/data spaces to store compiler
3891 A warning message will be generated when this happens and the compiler
3892 will indicate the number of extra bytes it allocated.
3893 It recommended that this option NOT be used, #pragma\SpecialChar ~
3895 to turn off global subexpression elimination for a given function only.
3897 \labelwidthstring 00.00.0000
3903 Will not do loop invariant optimizations, this may be turned off for reasons
3904 explained for the previous option.
3905 For more details of loop optimizations performed see section Loop Invariants.It
3906 recommended that this option NOT be used, #pragma\SpecialChar ~
3907 NOINVARIANT can be used
3908 to turn off invariant optimizations for a given function only.
3910 \labelwidthstring 00.00.0000
3916 Will not do loop induction optimizations, see section strength reduction
3917 for more details.It is recommended that this option is NOT used, #pragma\SpecialChar ~
3919 ION can be used to turn off induction optimizations for a given function
3922 \labelwidthstring 00.00.0000
3933 Will not generate boundary condition check when switch statements are implement
3934 ed using jump-tables.
3935 See section Switch Statements for more details.
3936 It is recommended that this option is NOT used, #pragma\SpecialChar ~
3938 used to turn off boundary checking for jump tables for a given function
3941 \labelwidthstring 00.00.0000
3950 Will not do loop reversal optimization.
3952 \labelwidthstring 00.00.0000
3958 Will not optimize labels (makes the dumpfiles more readable).
3960 \labelwidthstring 00.00.0000
3966 Will not memcpy initialized data in far space from code space.
3967 This saves a few bytes in code space if you don't have initialized data.
3968 \layout Subsubsection
3972 \labelwidthstring 00.00.0000
3979 will compile and assemble the source, but will not call the linkage editor.
3981 \labelwidthstring 00.00.0000
3987 reads the preprocessed source from standard input and compiles it.
3988 The file name for the assembler output must be specified using the -o option.
3990 \labelwidthstring 00.00.0000
3996 Run only the C preprocessor.
3997 Preprocess all the C source files specified and output the results to standard
4000 \labelwidthstring 00.00.0000
4007 The output path resp.
4008 file where everything will be placed.
4009 If the parameter is a path, it must have a trailing slash (or backslash
4010 for the Windows binaries) to be recognized as a path.
4013 \labelwidthstring 00.00.0000
4024 All functions in the source file will be compiled as
4029 the parameters and local variables will be allocated on the stack.
4030 see section Parameters and Local Variables for more details.
4031 If this option is used all source files in the project should be compiled
4035 \labelwidthstring 00.00.0000
4041 Uses a pseudo stack in the first 256 bytes in the external ram for allocating
4042 variables and passing parameters.
4043 See section on external stack for more details.
4045 \labelwidthstring 00.00.0000
4049 ---callee-saves function1[,function2][,function3]....
4052 The compiler by default uses a caller saves convention for register saving
4053 across function calls, however this can cause unneccessary register pushing
4054 & popping when calling small functions from larger functions.
4055 This option can be used to switch the register saving convention for the
4056 function names specified.
4057 The compiler will not save registers when calling these functions, no extra
4058 code will be generated at the entry & exit for these functions to save
4059 & restore the registers used by these functions, this can SUBSTANTIALLY
4060 reduce code & improve run time performance of the generated code.
4061 In the future the compiler (with interprocedural analysis) will be able
4062 to determine the appropriate scheme to use for each function call.
4063 DO NOT use this option for built-in functions such as _muluint..., if this
4064 option is used for a library function the appropriate library function
4065 needs to be recompiled with the same option.
4066 If the project consists of multiple source files then all the source file
4067 should be compiled with the same ---callee-saves option string.
4068 Also see #pragma\SpecialChar ~
4071 \labelwidthstring 00.00.0000
4080 When this option is used the compiler will generate debug information, that
4081 can be used with the SDCDB.
4082 The debug information is collected in a file with .cdb extension.
4083 For more information see documentation for SDCDB.
4085 \labelwidthstring 00.00.0000
4091 <filename> This option can be used to use additional rules to be used by
4092 the peep hole optimizer.
4093 See section Peep Hole optimizations for details on how to write these rules.
4095 \labelwidthstring 00.00.0000
4106 Stop after the stage of compilation proper; do not assemble.
4107 The output is an assembler code file for the input file specified.
4109 \labelwidthstring 00.00.0000
4113 -Wa_asmOption[,asmOption]
4116 Pass the asmOption to the assembler.
4118 \labelwidthstring 00.00.0000
4122 -Wl_linkOption[,linkOption]
4125 Pass the linkOption to the linker.
4127 \labelwidthstring 00.00.0000
4136 Integer (16 bit) and long (32 bit) libraries have been compiled as reentrant.
4137 Note by default these libraries are compiled as non-reentrant.
4138 See section Installation for more details.
4140 \labelwidthstring 00.00.0000
4149 This option will cause the compiler to generate an information message for
4150 each function in the source file.
4151 The message contains some
4155 information about the function.
4156 The number of edges and nodes the compiler detected in the control flow
4157 graph of the function, and most importantly the
4159 cyclomatic complexity
4161 see section on Cyclomatic Complexity for more details.
4163 \labelwidthstring 00.00.0000
4172 Floating point library is compiled as reentrant.See section Installation
4175 \labelwidthstring 00.00.0000
4181 The compiler will not overlay parameters and local variables of any function,
4182 see section Parameters and local variables for more details.
4184 \labelwidthstring 00.00.0000
4190 This option can be used when the code generated is called by a monitor
4192 The compiler will generate a 'ret' upon return from the 'main' function.
4193 The default option is to lock up i.e.
4196 \labelwidthstring 00.00.0000
4202 Disable peep-hole optimization.
4204 \labelwidthstring 00.00.0000
4210 Pass the inline assembler code through the peep hole optimizer.
4211 This can cause unexpected changes to inline assembler code, please go through
4212 the peephole optimizer rules defined in the source file tree '<target>/peeph.def
4213 ' before using this option.
4215 \labelwidthstring 00.00.0000
4221 <Value> Causes the linker to check if the internal ram usage is within limits
4224 \labelwidthstring 00.00.0000
4230 <Value> Causes the linker to check if the external ram usage is within limits
4233 \labelwidthstring 00.00.0000
4239 <Value> Causes the linker to check if the code usage is within limits of
4242 \labelwidthstring 00.00.0000
4248 This will prevent the compiler from passing on the default include path
4249 to the preprocessor.
4251 \labelwidthstring 00.00.0000
4257 This will prevent the compiler from passing on the default library path
4260 \labelwidthstring 00.00.0000
4266 Shows the various actions the compiler is performing.
4268 \labelwidthstring 00.00.0000
4274 Shows the actual commands the compiler is executing.
4276 \labelwidthstring 00.00.0000
4282 Hides your ugly and inefficient c-code from the asm file, so you can always
4283 blame the compiler :).
4285 \labelwidthstring 00.00.0000
4291 Include i-codes in the asm file.
4292 Sounds like noise but is most helpfull for debugging the compiler itself.
4294 \labelwidthstring 00.00.0000
4300 Disable some of the more pedantic warnings (jwk burps: please be more specific
4303 \labelwidthstring 00.00.0000
4307 ---print-search-dirs
4309 Display the directories in the compiler's search path
4310 \layout Subsubsection
4312 Intermediate Dump Options
4315 The following options are provided for the purpose of retargetting and debugging
4317 These provided a means to dump the intermediate code (iCode) generated
4318 by the compiler in human readable form at various stages of the compilation
4322 \labelwidthstring 00.00.0000
4328 This option will cause the compiler to dump the intermediate code into
4331 <source filename>.dumpraw
4333 just after the intermediate code has been generated for a function, i.e.
4334 before any optimizations are done.
4335 The basic blocks at this stage ordered in the depth first number, so they
4336 may not be in sequence of execution.
4338 \labelwidthstring 00.00.0000
4344 Will create a dump of iCode's, after global subexpression elimination,
4347 <source filename>.dumpgcse.
4349 \labelwidthstring 00.00.0000
4355 Will create a dump of iCode's, after deadcode elimination, into a file
4358 <source filename>.dumpdeadcode.
4360 \labelwidthstring 00.00.0000
4369 Will create a dump of iCode's, after loop optimizations, into a file named
4372 <source filename>.dumploop.
4374 \labelwidthstring 00.00.0000
4383 Will create a dump of iCode's, after live range analysis, into a file named
4386 <source filename>.dumprange.
4388 \labelwidthstring 00.00.0000
4394 Will dump the life ranges for all symbols.
4396 \labelwidthstring 00.00.0000
4405 Will create a dump of iCode's, after register assignment, into a file named
4408 <source filename>.dumprassgn.
4410 \labelwidthstring 00.00.0000
4416 Will create a dump of the live ranges of iTemp's
4418 \labelwidthstring 00.00.0000
4429 Will cause all the above mentioned dumps to be created.
4432 Environment variables
4435 SDCC recognizes the following environment variables:
4437 \labelwidthstring 00.00.0000
4443 SDCC installs a signal handler to be able to delete temporary files after
4444 an user break (^C) or an exception.
4445 If this environment variable is set, SDCC won't install the signal handler
4446 in order to be able to debug SDCC.
4448 \labelwidthstring 00.00.0000
4456 Path, where temporary files will be created.
4457 The order of the variables is the search order.
4458 In a standard *nix environment these variables are not set, and there's
4459 no need to set them.
4460 On Windows it's recommended to set one of them.
4462 \labelwidthstring 00.00.0000
4469 \begin_inset Quotes sld
4472 2.3 Install and search paths
4473 \begin_inset Quotes srd
4478 \labelwidthstring 00.00.0000
4485 \begin_inset Quotes sld
4488 2.3 Install and search paths
4489 \begin_inset Quotes srd
4494 \labelwidthstring 00.00.0000
4501 \begin_inset Quotes sld
4504 2.3 Install and search paths
4505 \begin_inset Quotes srd
4511 There are some more environment variables recognized by SDCC, but these
4512 are solely used for debugging purposes.
4513 They can change or disappear very quickly, and will never be documentated.
4516 MCS51/DS390 Storage Class Language Extensions
4519 In addition to the ANSI storage classes SDCC allows the following MCS51
4520 specific storage classes.
4521 \layout Subsubsection
4526 Variables declared with this storage class will be placed in the extern
4532 storage class for Large Memory model, e.g.:
4538 xdata unsigned char xduc;
4539 \layout Subsubsection
4548 storage class for Small Memory model.
4549 Variables declared with this storage class will be allocated in the internal
4557 \layout Subsubsection
4562 Variables declared with this storage class will be allocated into the indirectly
4563 addressable portion of the internal ram of a 8051, e.g.:
4570 \layout Subsubsection
4575 This is a data-type and a storage class specifier.
4576 When a variable is declared as a bit, it is allocated into the bit addressable
4577 memory of 8051, e.g.:
4584 \layout Subsubsection
4589 Like the bit keyword,
4593 signifies both a data-type and storage class, they are used to describe
4594 the special function registers and special bit variables of a 8051, eg:
4600 sfr at 0x80 P0; /* special function register P0 at location 0x80 */
4602 sbit at 0xd7 CY; /* CY (Carry Flag) */
4608 SDCC allows (via language extensions) pointers to explicitly point to any
4609 of the memory spaces of the 8051.
4610 In addition to the explicit pointers, the compiler uses (by default) generic
4611 pointers which can be used to point to any of the memory spaces.
4615 Pointer declaration examples:
4624 /* pointer physically in xternal ram pointing to object in internal ram
4627 data unsigned char * xdata p;
4631 /* pointer physically in code rom pointing to data in xdata space */
4633 xdata unsigned char * code p;
4637 /* pointer physically in code space pointing to data in code space */
4639 code unsigned char * code p;
4643 /* the folowing is a generic pointer physically located in xdata space */
4654 Well you get the idea.
4659 All unqualified pointers are treated as 3-byte (4-byte for the ds390)
4672 The highest order byte of the
4676 pointers contains the data space information.
4677 Assembler support routines are called whenever data is stored or retrieved
4683 These are useful for developing reusable library routines.
4684 Explicitly specifying the pointer type will generate the most efficient
4688 Parameters & Local Variables
4691 Automatic (local) variables and parameters to functions can either be placed
4692 on the stack or in data-space.
4693 The default action of the compiler is to place these variables in the internal
4694 RAM (for small model) or external RAM (for large model).
4695 This in fact makes them
4699 so by default functions are non-reentrant.
4703 They can be placed on the stack either by using the
4707 option or by using the
4711 keyword in the function declaration, e.g.:
4720 unsigned char foo(char i) reentrant
4733 Since stack space on 8051 is limited, the
4741 option should be used sparingly.
4742 Note that the reentrant keyword just means that the parameters & local
4743 variables will be allocated to the stack, it
4747 mean that the function is register bank independent.
4751 Local variables can be assigned storage classes and absolute addresses,
4758 unsigned char foo() {
4764 xdata unsigned char i;
4776 data at 0x31 unsiged char j;
4791 In the above example the variable
4795 will be allocated in the external ram,
4799 in bit addressable space and
4808 or when a function is declared as
4812 this should only be done for static variables.
4815 Parameters however are not allowed any storage class, (storage classes for
4816 parameters will be ignored), their allocation is governed by the memory
4817 model in use, and the reentrancy options.
4823 For non-reentrant functions SDCC will try to reduce internal ram space usage
4824 by overlaying parameters and local variables of a function (if possible).
4825 Parameters and local variables of a function will be allocated to an overlayabl
4826 e segment if the function has
4828 no other function calls and the function is non-reentrant and the memory
4832 If an explicit storage class is specified for a local variable, it will
4836 Note that the compiler (not the linkage editor) makes the decision for overlayin
4838 Functions that are called from an interrupt service routine should be preceded
4839 by a #pragma\SpecialChar ~
4840 NOOVERLAY if they are not reentrant.
4843 Also note that the compiler does not do any processing of inline assembler
4844 code, so the compiler might incorrectly assign local variables and parameters
4845 of a function into the overlay segment if the inline assembler code calls
4846 other c-functions that might use the overlay.
4847 In that case the #pragma\SpecialChar ~
4848 NOOVERLAY should be used.
4851 Parameters and Local variables of functions that contain 16 or 32 bit multiplica
4852 tion or division will NOT be overlayed since these are implemented using
4853 external functions, e.g.:
4863 void set_error(unsigned char errcd)
4879 void some_isr () interrupt 2 using 1
4908 In the above example the parameter
4916 would be assigned to the overlayable segment if the #pragma\SpecialChar ~
4918 not present, this could cause unpredictable runtime behavior when called
4920 The #pragma\SpecialChar ~
4921 NOOVERLAY ensures that the parameters and local variables for
4922 the function are NOT overlayed.
4925 Interrupt Service Routines
4928 SDCC allows interrupt service routines to be coded in C, with some extended
4935 void timer_isr (void) interrupt 2 using 1
4948 The number following the
4952 keyword is the interrupt number this routine will service.
4953 The compiler will insert a call to this routine in the interrupt vector
4954 table for the interrupt number specified.
4959 keyword is used to tell the compiler to use the specified register bank
4960 (8051 specific) when generating code for this function.
4961 Note that when some function is called from an interrupt service routine
4962 it should be preceded by a #pragma\SpecialChar ~
4963 NOOVERLAY if it is not reentrant.
4964 A special note here, int (16 bit) and long (32 bit) integer division, multiplic
4965 ation & modulus operations are implemented using external support routines
4966 developed in ANSI-C, if an interrupt service routine needs to do any of
4967 these operations then the support routines (as mentioned in a following
4968 section) will have to be recompiled using the
4972 option and the source file will need to be compiled using the
4979 If you have multiple source files in your project, interrupt service routines
4980 can be present in any of them, but a prototype of the isr MUST be present
4981 or included in the file that contains the function
4988 Interrupt Numbers and the corresponding address & descriptions for the Standard
4989 8051 are listed below.
4990 SDCC will automatically adjust the interrupt vector table to the maximum
4991 interrupt number specified.
4997 \begin_inset Tabular
4998 <lyxtabular version="3" rows="6" columns="3">
5000 <column alignment="center" valignment="top" leftline="true" width="0in">
5001 <column alignment="center" valignment="top" leftline="true" width="0in">
5002 <column alignment="center" valignment="top" leftline="true" rightline="true" width="0in">
5003 <row topline="true" bottomline="true">
5004 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
5012 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
5020 <cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
5029 <row topline="true">
5030 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
5038 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
5046 <cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
5055 <row topline="true">
5056 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
5064 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
5072 <cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
5081 <row topline="true">
5082 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
5090 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
5098 <cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
5107 <row topline="true">
5108 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
5116 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
5124 <cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
5133 <row topline="true" bottomline="true">
5134 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
5142 <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
5150 <cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
5167 If the interrupt service routine is defined without
5171 a register bank or with register bank 0 (using 0), the compiler will save
5172 the registers used by itself on the stack upon entry and restore them at
5173 exit, however if such an interrupt service routine calls another function
5174 then the entire register bank will be saved on the stack.
5175 This scheme may be advantageous for small interrupt service routines which
5176 have low register usage.
5179 If the interrupt service routine is defined to be using a specific register
5184 are save and restored, if such an interrupt service routine calls another
5185 function (using another register bank) then the entire register bank of
5186 the called function will be saved on the stack.
5187 This scheme is recommended for larger interrupt service routines.
5190 Calling other functions from an interrupt service routine is not recommended,
5191 avoid it if possible.
5195 Also see the _naked modifier.
5203 <TODO: this isn't implemented at all!>
5209 A special keyword may be associated with a function declaring it as
5214 SDCC will generate code to disable all interrupts upon entry to a critical
5215 function and enable them back before returning.
5216 Note that nesting critical functions may cause unpredictable results.
5241 The critical attribute maybe used with other attributes like
5249 A special keyword may be associated with a function declaring it as
5258 function modifier attribute prevents the compiler from generating prologue
5259 and epilogue code for that function.
5260 This means that the user is entirely responsible for such things as saving
5261 any registers that may need to be preserved, selecting the proper register
5262 bank, generating the
5266 instruction at the end, etc.
5267 Practically, this means that the contents of the function must be written
5268 in inline assembler.
5269 This is particularly useful for interrupt functions, which can have a large
5270 (and often unnecessary) prologue/epilogue.
5271 For example, compare the code generated by these two functions:
5277 data unsigned char counter;
5279 void simpleInterrupt(void) interrupt 1
5293 void nakedInterrupt(void) interrupt 2 _naked
5326 ; MUST explicitly include ret in _naked function.
5340 For an 8051 target, the generated simpleInterrupt looks like:
5485 whereas nakedInterrupt looks like:
5510 ; MUST explicitly include ret(i) in _naked function.
5516 While there is nothing preventing you from writing C code inside a _naked
5517 function, there are many ways to shoot yourself in the foot doing this,
5518 and it is recommended that you stick to inline assembler.
5521 Functions using private banks
5528 attribute (which tells the compiler to use a register bank other than the
5529 default bank zero) should only be applied to
5533 functions (see note 1 below).
5534 This will in most circumstances make the generated ISR code more efficient
5535 since it will not have to save registers on the stack.
5542 attribute will have no effect on the generated code for a
5546 function (but may occasionally be useful anyway
5552 possible exception: if a function is called ONLY from 'interrupt' functions
5553 using a particular bank, it can be declared with the same 'using' attribute
5554 as the calling 'interrupt' functions.
5555 For instance, if you have several ISRs using bank one, and all of them
5556 call memcpy(), it might make sense to create a specialized version of memcpy()
5557 'using 1', since this would prevent the ISR from having to save bank zero
5558 to the stack on entry and switch to bank zero before calling the function
5565 (pending: I don't think this has been done yet)
5572 function using a non-zero bank will assume that it can trash that register
5573 bank, and will not save it.
5574 Since high-priority interrupts can interrupt low-priority ones on the 8051
5575 and friends, this means that if a high-priority ISR
5579 a particular bank occurs while processing a low-priority ISR
5583 the same bank, terrible and bad things can happen.
5584 To prevent this, no single register bank should be
5588 by both a high priority and a low priority ISR.
5589 This is probably most easily done by having all high priority ISRs use
5590 one bank and all low priority ISRs use another.
5591 If you have an ISR which can change priority at runtime, you're on your
5592 own: I suggest using the default bank zero and taking the small performance
5596 It is most efficient if your ISR calls no other functions.
5597 If your ISR must call other functions, it is most efficient if those functions
5598 use the same bank as the ISR (see note 1 below); the next best is if the
5599 called functions use bank zero.
5600 It is very inefficient to call a function using a different, non-zero bank
5608 Data items can be assigned an absolute address with the
5612 keyword, in addition to a storage class, e.g.:
5618 xdata at 0x8000 unsigned char PORTA_8255 ;
5624 In the above example the PORTA_8255 will be allocated to the location 0x8000
5625 of the external ram.
5626 Note that this feature is provided to give the programmer access to
5630 devices attached to the controller.
5631 The compiler does not actually reserve any space for variables declared
5632 in this way (they are implemented with an equate in the assembler).
5633 Thus it is left to the programmer to make sure there are no overlaps with
5634 other variables that are declared without the absolute address.
5635 The assembler listing file (.lst) and the linker output files (.rst) and
5636 (.map) are a good places to look for such overlaps.
5640 Absolute address can be specified for variables in all storage classes,
5653 The above example will allocate the variable at offset 0x02 in the bit-addressab
5655 There is no real advantage to assigning absolute addresses to variables
5656 in this manner, unless you want strict control over all the variables allocated.
5662 The compiler inserts a call to the C routine
5664 _sdcc_external_startup()
5669 at the start of the CODE area.
5670 This routine is in the runtime library.
5671 By default this routine returns 0, if this routine returns a non-zero value,
5672 the static & global variable initialization will be skipped and the function
5673 main will be invoked Other wise static & global variables will be initialized
5674 before the function main is invoked.
5677 _sdcc_external_startup()
5679 routine to your program to override the default if you need to setup hardware
5680 or perform some other critical operation prior to static & global variable
5684 Inline Assembler Code
5687 SDCC allows the use of in-line assembler with a few restriction as regards
5689 All labels defined within inline assembler code
5697 where nnnn is a number less than 100 (which implies a limit of utmost 100
5698 inline assembler labels
5706 It is strongly recommended that each assembly instruction (including labels)
5707 be placed in a separate line (as the example shows).
5712 command line option is used, the inline assembler code will be passed through
5713 the peephole optimizer.
5714 This might cause some unexpected changes in the inline assembler code.
5715 Please go throught the peephole optimizer rules defined in file
5719 carefully before using this option.
5759 The inline assembler code can contain any valid code understood by the assembler
5760 , this includes any assembler directives and comment lines.
5761 The compiler does not do any validation of the code within the
5771 Inline assembler code cannot reference any C-Labels, however it can reference
5772 labels defined by the inline assembler, e.g.:
5798 ; some assembler code
5818 /* some more c code */
5820 clabel:\SpecialChar ~
5822 /* inline assembler cannot reference this label */
5834 $0003: ;label (can be reference by inline assembler only)
5846 /* some more c code */
5854 In other words inline assembly code can access labels defined in inline
5855 assembly within the scope of the funtion.
5859 The same goes the other way, ie.
5860 labels defines in inline assembly CANNOT be accessed by C statements.
5863 int (16 bit) and long (32 bit) Support
5866 For signed & unsigned int (16 bit) and long (32 bit) variables, division,
5867 multiplication and modulus operations are implemented by support routines.
5868 These support routines are all developed in ANSI-C to facilitate porting
5869 to other MCUs, although some model specific assembler optimations are used.
5870 The following files contain the described routine, all of them can be found
5871 in <installdir>/share/sdcc/lib.
5877 <pending: tabularise this>
5883 _mulsint.c - signed 16 bit multiplication (calls _muluint)
5885 _muluint.c - unsigned 16 bit multiplication
5887 _divsint.c - signed 16 bit division (calls _divuint)
5889 _divuint.c - unsigned 16 bit division
5891 _modsint.c - signed 16 bit modulus (call _moduint)
5893 _moduint.c - unsigned 16 bit modulus
5895 _mulslong.c - signed 32 bit multiplication (calls _mululong)
5897 _mululong.c - unsigned32 bit multiplication
5899 _divslong.c - signed 32 division (calls _divulong)
5901 _divulong.c - unsigned 32 division
5903 _modslong.c - signed 32 bit modulus (calls _modulong)
5905 _modulong.c - unsigned 32 bit modulus
5913 Since they are compiled as
5917 , interrupt service routines should not do any of the above operations.
5918 If this is unavoidable then the above routines will need to be compiled
5923 option, after which the source program will have to be compiled with
5930 Floating Point Support
5933 SDCC supports IEEE (single precision 4bytes) floating point numbers.The floating
5934 point support routines are derived from gcc's floatlib.c and consists of
5935 the following routines:
5941 <pending: tabularise this>
5947 _fsadd.c - add floating point numbers
5949 _fssub.c - subtract floating point numbers
5951 _fsdiv.c - divide floating point numbers
5953 _fsmul.c - multiply floating point numbers
5955 _fs2uchar.c - convert floating point to unsigned char
5957 _fs2char.c - convert floating point to signed char
5959 _fs2uint.c - convert floating point to unsigned int
5961 _fs2int.c - convert floating point to signed int
5963 _fs2ulong.c - convert floating point to unsigned long
5965 _fs2long.c - convert floating point to signed long
5967 _uchar2fs.c - convert unsigned char to floating point
5969 _char2fs.c - convert char to floating point number
5971 _uint2fs.c - convert unsigned int to floating point
5973 _int2fs.c - convert int to floating point numbers
5975 _ulong2fs.c - convert unsigned long to floating point number
5977 _long2fs.c - convert long to floating point number
5985 Note if all these routines are used simultaneously the data space might
5987 For serious floating point usage it is strongly recommended that the large
5994 SDCC allows two memory models for MCS51 code, small and large.
5995 Modules compiled with different memory models should
5999 be combined together or the results would be unpredictable.
6000 The library routines supplied with the compiler are compiled as both small
6002 The compiled library modules are contained in seperate directories as small
6003 and large so that you can link to either set.
6007 When the large model is used all variables declared without a storage class
6008 will be allocated into the external ram, this includes all parameters and
6009 local variables (for non-reentrant functions).
6010 When the small model is used variables without storage class are allocated
6011 in the internal ram.
6014 Judicious usage of the processor specific storage classes and the 'reentrant'
6015 function type will yield much more efficient code, than using the large
6017 Several optimizations are disabled when the program is compiled using the
6018 large model, it is therefore strongly recommdended that the small model
6019 be used unless absolutely required.
6025 The only model supported is Flat 24.
6026 This generates code for the 24 bit contiguous addressing mode of the Dallas
6028 In this mode, up to four meg of external RAM or code space can be directly
6030 See the data sheets at www.dalsemi.com for further information on this part.
6034 In older versions of the compiler, this option was used with the MCS51 code
6040 Now, however, the '390 has it's own code generator, selected by the
6049 Note that the compiler does not generate any code to place the processor
6050 into 24 bitmode (although
6054 in the ds390 libraries will do that for you).
6059 , the boot loader or similar code must ensure that the processor is in 24
6060 bit contiguous addressing mode before calling the SDCC startup code.
6068 option, variables will by default be placed into the XDATA segment.
6073 Segments may be placed anywhere in the 4 meg address space using the usual
6075 Note that if any segments are located above 64K, the -r flag must be passed
6076 to the linker to generate the proper segment relocations, and the Intel
6077 HEX output format must be used.
6078 The -r flag can be passed to the linker by using the option
6082 on the sdcc command line.
6083 However, currently the linker can not handle code segments > 64k.
6086 Defines Created by the Compiler
6089 The compiler creates the following #defines.
6092 SDCC - this Symbol is always defined.
6095 SDCC_mcs51 or SDCC_ds390 or SDCC_z80, etc - depending on the model used
6099 __mcs51 or __ds390 or __z80, etc - depending on the model used (e.g.
6103 SDCC_STACK_AUTO - this symbol is defined when
6110 SDCC_MODEL_SMALL - when
6117 SDCC_MODEL_LARGE - when
6124 SDCC_USE_XSTACK - when
6131 SDCC_STACK_TENBIT - when
6138 SDCC_MODEL_FLAT24 - when
6151 SDCC performs a host of standard optimizations in addition to some MCU specific
6154 \layout Subsubsection
6156 Sub-expression Elimination
6159 The compiler does local and global common subexpression elimination, e.g.:
6174 will be translated to
6190 Some subexpressions are not as obvious as the above example, e.g.:
6204 In this case the address arithmetic a->b[i] will be computed only once;
6205 the equivalent code in C would be.
6221 The compiler will try to keep these temporary variables in registers.
6222 \layout Subsubsection
6224 Dead-Code Elimination
6239 i = 1; \SpecialChar ~
6244 global = 1;\SpecialChar ~
6257 global = 3;\SpecialChar ~
6272 int global; void f ()
6285 \layout Subsubsection
6346 Note: the dead stores created by this copy propagation will be eliminated
6347 by dead-code elimination.
6348 \layout Subsubsection
6353 Two types of loop optimizations are done by SDCC loop invariant lifting
6354 and strength reduction of loop induction variables.
6355 In addition to the strength reduction the optimizer marks the induction
6356 variables and the register allocator tries to keep the induction variables
6357 in registers for the duration of the loop.
6358 Because of this preference of the register allocator, loop induction optimizati
6359 on causes an increase in register pressure, which may cause unwanted spilling
6360 of other temporary variables into the stack / data space.
6361 The compiler will generate a warning message when it is forced to allocate
6362 extra space either on the stack or data space.
6363 If this extra space allocation is undesirable then induction optimization
6364 can be eliminated either for the entire source file (with ---noinduction
6365 option) or for a given function only using #pragma\SpecialChar ~
6376 for (i = 0 ; i < 100 ; i ++)
6394 for (i = 0; i < 100; i++)
6404 As mentioned previously some loop invariants are not as apparent, all static
6405 address computations are also moved out of the loop.
6409 Strength Reduction, this optimization substitutes an expression by a cheaper
6416 for (i=0;i < 100; i++)
6436 for (i=0;i< 100;i++) {
6440 ar[itemp1] = itemp2;
6456 The more expensive multiplication is changed to a less expensive addition.
6457 \layout Subsubsection
6462 This optimization is done to reduce the overhead of checking loop boundaries
6463 for every iteration.
6464 Some simple loops can be reversed and implemented using a
6465 \begin_inset Quotes eld
6468 decrement and jump if not zero
6469 \begin_inset Quotes erd
6473 SDCC checks for the following criterion to determine if a loop is reversible
6474 (note: more sophisticated compilers use data-dependency analysis to make
6475 this determination, SDCC uses a more simple minded analysis).
6478 The 'for' loop is of the form
6484 for (<symbol> = <expression> ; <sym> [< | <=] <expression> ; [<sym>++ |
6494 The <for body> does not contain
6495 \begin_inset Quotes eld
6499 \begin_inset Quotes erd
6503 \begin_inset Quotes erd
6509 All goto's are contained within the loop.
6512 No function calls within the loop.
6515 The loop control variable <sym> is not assigned any value within the loop
6518 The loop control variable does NOT participate in any arithmetic operation
6522 There are NO switch statements in the loop.
6523 \layout Subsubsection
6525 Algebraic Simplifications
6528 SDCC does numerous algebraic simplifications, the following is a small sub-set
6529 of these optimizations.
6535 i = j + 0 ; /* changed to */ i = j;
6537 i /= 2; /* changed to */ i >>= 1;
6539 i = j - j ; /* changed to */ i = 0;
6541 i = j / 1 ; /* changed to */ i = j;
6547 Note the subexpressions given above are generally introduced by macro expansions
6548 or as a result of copy/constant propagation.
6549 \layout Subsubsection
6554 SDCC changes switch statements to jump tables when the following conditions
6559 The case labels are in numerical sequence, the labels need not be in order,
6560 and the starting number need not be one or zero.
6566 switch(i) {\SpecialChar ~
6673 Both the above switch statements will be implemented using a jump-table.
6676 The number of case labels is at least three, since it takes two conditional
6677 statements to handle the boundary conditions.
6680 The number of case labels is less than 84, since each label takes 3 bytes
6681 and a jump-table can be utmost 256 bytes long.
6685 Switch statements which have gaps in the numeric sequence or those that
6686 have more that 84 case labels can be split into more than one switch statement
6687 for efficient code generation, e.g.:
6725 If the above switch statement is broken down into two switch statements
6759 case 9: \SpecialChar ~
6769 case 12:\SpecialChar ~
6779 then both the switch statements will be implemented using jump-tables whereas
6780 the unmodified switch statement will not be.
6781 \layout Subsubsection
6783 Bit-shifting Operations.
6786 Bit shifting is one of the most frequently used operation in embedded programmin
6788 SDCC tries to implement bit-shift operations in the most efficient way
6808 generates the following code:
6826 In general SDCC will never setup a loop if the shift count is known.
6866 Note that SDCC stores numbers in little-endian format (i.e.
6867 lowest order first).
6868 \layout Subsubsection
6873 A special case of the bit-shift operation is bit rotation, SDCC recognizes
6874 the following expression to be a left bit-rotation:
6885 i = ((i << 1) | (i >> 7));
6893 will generate the following code:
6909 SDCC uses pattern matching on the parse tree to determine this operation.Variatio
6910 ns of this case will also be recognized as bit-rotation, i.e.:
6916 i = ((i >> 7) | (i << 1)); /* left-bit rotation */
6917 \layout Subsubsection
6922 It is frequently required to obtain the highest order bit of an integral
6923 type (long, int, short or char types).
6924 SDCC recognizes the following expression to yield the highest order bit
6925 and generates optimized code for it, e.g.:
6946 hob = (gint >> 15) & 1;
6959 will generate the following code:
6998 000A E5*01\SpecialChar ~
7026 000C 33\SpecialChar ~
7057 000D E4\SpecialChar ~
7088 000E 13\SpecialChar ~
7119 000F F5*02\SpecialChar ~
7149 Variations of this case however will
7154 It is a standard C expression, so I heartily recommend this be the only
7155 way to get the highest order bit, (it is portable).
7156 Of course it will be recognized even if it is embedded in other expressions,
7163 xyz = gint + ((gint >> 15) & 1);
7169 will still be recognized.
7170 \layout Subsubsection
7175 The compiler uses a rule based, pattern matching and re-writing mechanism
7176 for peep-hole optimization.
7181 a peep-hole optimizer by Christopher W.
7182 Fraser (cwfraser@microsoft.com).
7183 A default set of rules are compiled into the compiler, additional rules
7184 may be added with the
7186 ---peep-file <filename>
7189 The rule language is best illustrated with examples.
7217 The above rule will change the following assembly sequence:
7247 Note: All occurrences of a
7251 (pattern variable) must denote the same string.
7252 With the above rule, the assembly sequence:
7270 will remain unmodified.
7274 Other special case optimizations may be added by the user (via
7280 some variants of the 8051 MCU allow only
7289 The following two rules will change all
7311 replace { lcall %1 } by { acall %1 }
7313 replace { ljmp %1 } by { ajmp %1 }
7321 inline-assembler code
7323 is also passed through the peep hole optimizer, thus the peephole optimizer
7324 can also be used as an assembly level macro expander.
7325 The rules themselves are MCU dependent whereas the rule language infra-structur
7326 e is MCU independent.
7327 Peephole optimization rules for other MCU can be easily programmed using
7332 The syntax for a rule is as follows:
7338 rule := replace [ restart ] '{' <assembly sequence> '
7376 <assembly sequence> '
7394 '}' [if <functionName> ] '
7402 <assembly sequence> := assembly instruction (each instruction including
7403 labels must be on a separate line).
7407 The optimizer will apply to the rules one by one from the top in the sequence
7408 of their appearance, it will terminate when all rules are exhausted.
7409 If the 'restart' option is specified, then the optimizer will start matching
7410 the rules again from the top, this option for a rule is expensive (performance)
7411 , it is intended to be used in situations where a transformation will trigger
7412 the same rule again.
7413 An example of this (not a good one, it has side effects) is the following
7440 Note that the replace pattern cannot be a blank, but can be a comment line.
7441 Without the 'restart' option only the inner most 'pop' 'push' pair would
7442 be eliminated, i.e.:
7494 the restart option the rule will be applied again to the resulting code
7495 and then all the pop-push pairs will be eliminated to yield:
7513 A conditional function can be attached to a rule.
7514 Attaching rules are somewhat more involved, let me illustrate this with
7545 The optimizer does a look-up of a function name table defined in function
7550 in the source file SDCCpeeph.c, with the name
7555 If it finds a corresponding entry the function is called.
7556 Note there can be no parameters specified for these functions, in this
7561 is crucial, since the function
7565 expects to find the label in that particular variable (the hash table containin
7566 g the variable bindings is passed as a parameter).
7567 If you want to code more such functions, take a close look at the function
7568 labelInRange and the calling mechanism in source file SDCCpeeph.c.
7569 I know this whole thing is a little kludgey, but maybe some day we will
7570 have some better means.
7571 If you are looking at this file, you will also see the default rules that
7572 are compiled into the compiler, you can add your own rules in the default
7573 set there if you get tired of specifying the ---peep-file option.
7579 SDCC supports the following #pragma directives.
7582 SAVE - this will save all current options to the SAVE/RESTORE stack.
7586 RESTORE - will restore saved options from the last save.
7587 SAVEs & RESTOREs can be nested.
7588 SDCC uses a SAVE/RESTORE stack: SAVE pushes current options to the stack,
7589 RESTORE pulls current options from the stack.
7593 NOGCSE - will stop global subexpression elimination.
7596 NOINDUCTION - will stop loop induction optimizations.
7599 NOJTBOUND - will not generate code for boundary value checking, when switch
7600 statements are turned into jump-tables.
7603 NOOVERLAY - the compiler will not overlay the parameters and local variables
7607 LESS_PEDANTIC - the compiler will not warn you anymore for obvious mistakes,
7608 you'r on your own now ;-(
7611 NOLOOPREVERSE - Will not do loop reversal optimization
7614 EXCLUDE NONE | {acc[,b[,dpl[,dph]]] - The exclude pragma disables generation
7615 of pair of push/pop instruction in ISR function (using interrupt keyword).
7616 The directive should be placed immediately before the ISR function definition
7617 and it affects ALL ISR functions following it.
7618 To enable the normal register saving for ISR functions use #pragma\SpecialChar ~
7619 EXCLUDE\SpecialChar ~
7623 NOIV - Do not generate interrupt vector table entries for all ISR functions
7624 defined after the pragma.
7625 This is useful in cases where the interrupt vector table must be defined
7626 manually, or when there is a secondary, manually defined interrupt vector
7628 for the autovector feature of the Cypress EZ-USB FX2).
7631 CALLEE-SAVES function1[,function2[,function3...]] - The compiler by default
7632 uses a caller saves convention for register saving across function calls,
7633 however this can cause unneccessary register pushing & popping when calling
7634 small functions from larger functions.
7635 This option can be used to switch off the register saving convention for
7636 the function names specified.
7637 The compiler will not save registers when calling these functions, extra
7638 code need to be manually inserted at the entry & exit for these functions
7639 to save & restore the registers used by these functions, this can SUBSTANTIALLY
7640 reduce code & improve run time performance of the generated code.
7641 In the future the compiler (with interprocedural analysis) may be able
7642 to determine the appropriate scheme to use for each function call.
7643 If ---callee-saves command line option is used, the function names specified
7644 in #pragma\SpecialChar ~
7645 CALLEE-SAVES is appended to the list of functions specified in
7649 The pragma's are intended to be used to turn-off certain optimizations which
7650 might cause the compiler to generate extra stack / data space to store
7651 compiler generated temporary variables.
7652 This usually happens in large functions.
7653 Pragma directives should be used as shown in the following example, they
7654 are used to control options & optimizations for a given function; pragmas
7655 should be placed before and/or after a function, placing pragma's inside
7656 a function body could have unpredictable results.
7662 #pragma SAVE /* save the current settings */
7664 #pragma NOGCSE /* turnoff global subexpression elimination */
7666 #pragma NOINDUCTION /* turn off induction optimizations */
7688 #pragma RESTORE /* turn the optimizations back on */
7694 The compiler will generate a warning message when extra space is allocated.
7695 It is strongly recommended that the SAVE and RESTORE pragma's be used when
7696 changing options for a function.
7701 <pending: this is messy and incomplete>
7706 Compiler support routines (_gptrget, _mulint etc)
7709 Stdclib functions (puts, printf, strcat etc)
7712 Math functions (sin, pow, sqrt etc)
7715 Interfacing with Assembly Routines
7716 \layout Subsubsection
7718 Global Registers used for Parameter Passing
7721 The compiler always uses the global registers
7729 to pass the first parameter to a routine.
7730 The second parameter onwards is either allocated on the stack (for reentrant
7731 routines or if ---stack-auto is used) or in the internal / external ram
7732 (depending on the memory model).
7734 \layout Subsubsection
7736 Assembler Routine(non-reentrant)
7739 In the following example the function cfunc calls an assembler routine asm_func,
7740 which takes two parameters.
7746 extern int asm_func(unsigned char, unsigned char);
7750 int c_func (unsigned char i, unsigned char j)
7758 return asm_func(i,j);
7772 return c_func(10,9);
7780 The corresponding assembler function is:
7786 .globl _asm_func_PARM_2
7850 add a,_asm_func_PARM_2
7886 Note here that the return values are placed in 'dpl' - One byte return value,
7887 'dpl' LSB & 'dph' MSB for two byte values.
7888 'dpl', 'dph' and 'b' for three byte values (generic pointers) and 'dpl','dph','
7889 b' & 'acc' for four byte values.
7892 The parameter naming convention is _<function_name>_PARM_<n>, where n is
7893 the parameter number starting from 1, and counting from the left.
7894 The first parameter is passed in
7895 \begin_inset Quotes eld
7899 \begin_inset Quotes erd
7902 for One bye parameter,
7903 \begin_inset Quotes eld
7907 \begin_inset Quotes erd
7911 \begin_inset Quotes eld
7915 \begin_inset Quotes erd
7919 \begin_inset Quotes eld
7923 \begin_inset Quotes erd
7926 for four bytes, the varible name for the second parameter will be _<function_na
7931 Assemble the assembler routine with the following command:
7938 asx8051 -losg asmfunc.asm
7945 Then compile and link the assembler routine to the C source file with the
7953 sdcc cfunc.c asmfunc.rel
7954 \layout Subsubsection
7956 Assembler Routine(reentrant)
7959 In this case the second parameter onwards will be passed on the stack, the
7960 parameters are pushed from right to left i.e.
7961 after the call the left most parameter will be on the top of the stack.
7968 extern int asm_func(unsigned char, unsigned char);
7972 int c_func (unsigned char i, unsigned char j) reentrant
7980 return asm_func(i,j);
7994 return c_func(10,9);
8002 The corresponding assembler routine is:
8112 The compiling and linking procedure remains the same, however note the extra
8113 entry & exit linkage required for the assembler code, _bp is the stack
8114 frame pointer and is used to compute the offset into the stack for parameters
8115 and local variables.
8121 The external stack is located at the start of the external ram segment,
8122 and is 256 bytes in size.
8123 When ---xstack option is used to compile the program, the parameters and
8124 local variables of all reentrant functions are allocated in this area.
8125 This option is provided for programs with large stack space requirements.
8126 When used with the ---stack-auto option, all parameters and local variables
8127 are allocated on the external stack (note support libraries will need to
8128 be recompiled with the same options).
8131 The compiler outputs the higher order address byte of the external ram segment
8132 into PORT P2, therefore when using the External Stack option, this port
8133 MAY NOT be used by the application program.
8139 Deviations from the compliancy.
8142 functions are not always reentrant.
8145 structures cannot be assigned values directly, cannot be passed as function
8146 parameters or assigned to each other and cannot be a return value from
8173 s1 = s2 ; /* is invalid in SDCC although allowed in ANSI */
8184 struct s foo1 (struct s parms) /* is invalid in SDCC although allowed in
8206 return rets;/* is invalid in SDCC although allowed in ANSI */
8211 'long long' (64 bit integers) not supported.
8214 'double' precision floating point not supported.
8217 No support for setjmp and longjmp (for now).
8220 Old K&R style function declarations are NOT allowed.
8226 foo(i,j) /* this old style of function declarations */
8228 int i,j; /* are valid in ANSI but not valid in SDCC */
8242 functions declared as pointers must be dereferenced during the call.
8253 /* has to be called like this */
8255 (*foo)(); /* ansi standard allows calls to be made like 'foo()' */
8258 Cyclomatic Complexity
8261 Cyclomatic complexity of a function is defined as the number of independent
8262 paths the program can take during execution of the function.
8263 This is an important number since it defines the number test cases you
8264 have to generate to validate the function.
8265 The accepted industry standard for complexity number is 10, if the cyclomatic
8266 complexity reported by SDCC exceeds 10 you should think about simplification
8267 of the function logic.
8268 Note that the complexity level is not related to the number of lines of
8270 Large functions can have low complexity, and small functions can have large
8276 SDCC uses the following formula to compute the complexity:
8281 complexity = (number of edges in control flow graph) - (number of nodes
8282 in control flow graph) + 2;
8286 Having said that the industry standard is 10, you should be aware that in
8287 some cases it be may unavoidable to have a complexity level of less than
8289 For example if you have switch statement with more than 10 case labels,
8290 each case label adds one to the complexity level.
8291 The complexity level is by no means an absolute measure of the algorithmic
8292 complexity of the function, it does however provide a good starting point
8293 for which functions you might look at for further optimization.
8299 Here are a few guidelines that will help the compiler generate more efficient
8300 code, some of the tips are specific to this compiler others are generally
8301 good programming practice.
8304 Use the smallest data type to represent your data-value.
8305 If it is known in advance that the value is going to be less than 256 then
8306 use an 'unsigned char' instead of a 'short' or 'int'.
8309 Use unsigned when it is known in advance that the value is not going to
8311 This helps especially if you are doing division or multiplication.
8314 NEVER jump into a LOOP.
8317 Declare the variables to be local whenever possible, especially loop control
8318 variables (induction).
8321 Since the compiler does not always do implicit integral promotion, the programme
8322 r should do an explicit cast when integral promotion is required.
8325 Reducing the size of division, multiplication & modulus operations can reduce
8326 code size substantially.
8327 Take the following code for example.
8333 foobar(unsigned int p1, unsigned char ch)
8337 unsigned char ch1 = p1 % ch ;
8348 For the modulus operation the variable ch will be promoted to unsigned int
8349 first then the modulus operation will be performed (this will lead to a
8350 call to support routine _moduint()), and the result will be casted to a
8352 If the code is changed to
8358 foobar(unsigned int p1, unsigned char ch)
8362 unsigned char ch1 = (unsigned char)p1 % ch ;
8373 It would substantially reduce the code generated (future versions of the
8374 compiler will be smart enough to detect such optimization oppurtunities).
8377 Notes on MCS51 memory layout
8380 The 8051 family of micro controller have a minimum of 128 bytes of internal
8381 memory which is structured as follows
8385 - Bytes 00-1F - 32 bytes to hold up to 4 banks of the registers R7 to R7
8388 - Bytes 20-2F - 16 bytes to hold 128 bit variables and
8390 - Bytes 30-7F - 60 bytes for general purpose use.
8394 Normally the SDCC compiler will only utilise the first bank of registers,
8395 but it is possible to specify that other banks of registers should be used
8396 in interrupt routines.
8397 By default, the compiler will place the stack after the last bank of used
8399 if the first 2 banks of registers are used, it will position the base of
8400 the internal stack at address 16 (0X10).
8401 This implies that as the stack grows, it will use up the remaining register
8402 banks, and the 16 bytes used by the 128 bit variables, and 60 bytes for
8403 general purpose use.
8406 By default, the compiler uses the 60 general purpose bytes to hold "near
8408 The compiler/optimiser may also declare some Local Variables in this area
8413 If any of the 128 bit variables are used, or near data is being used then
8414 care needs to be taken to ensure that the stack does not grow so much that
8415 it starts to over write either your bit variables or "near data".
8416 There is no runtime checking to prevent this from happening.
8419 The amount of stack being used is affected by the use of the "internal stack"
8420 to save registers before a subroutine call is made (---stack-auto will
8421 declare parameters and local variables on the stack) and the number of
8425 If you detect that the stack is over writing you data, then the following
8427 ---xstack will cause an external stack to be used for saving registers
8428 and (if ---stack-auto is being used) storing parameters and local variables.
8429 However this will produce more code which will be slower to execute.
8433 ---stack-loc will allow you specify the start of the stack, i.e.
8434 you could start it after any data in the general purpose area.
8435 However this may waste the memory not used by the register banks and if
8436 the size of the "near data" increases, it may creep into the bottom of
8440 ---stack-after-data, similar to the ---stack-loc, but it automatically places
8441 the stack after the end of the "near data".
8442 Again this could waste any spare register space.
8445 ---data-loc allows you to specify the start address of the near data.
8446 This could be used to move the "near data" further away from the stack
8447 giving it more room to grow.
8448 This will only work if no bit variables are being used and the stack can
8449 grow to use the bit variable space.
8457 If you find that the stack is over writing your bit variables or "near data"
8458 then the approach which best utilised the internal memory is to position
8459 the "near data" after the last bank of used registers or, if you use bit
8460 variables, after the last bit variable by using the ---data-loc, e.g.
8461 if two register banks are being used and no bit variables, ---data-loc
8462 16, and use the ---stack-after-data option.
8465 If bit variables are being used, another method would be to try and squeeze
8466 the data area in the unused register banks if it will fit, and start the
8467 stack after the last bit variable.
8470 Retargetting for other MCUs.
8473 The issues for retargetting the compiler are far too numerous to be covered
8475 What follows is a brief description of each of the seven phases of the
8476 compiler and its MCU dependency.
8479 Parsing the source and building the annotated parse tree.
8480 This phase is largely MCU independent (except for the language extensions).
8481 Syntax & semantic checks are also done in this phase, along with some initial
8482 optimizations like back patching labels and the pattern matching optimizations
8483 like bit-rotation etc.
8486 The second phase involves generating an intermediate code which can be easy
8487 manipulated during the later phases.
8488 This phase is entirely MCU independent.
8489 The intermediate code generation assumes the target machine has unlimited
8490 number of registers, and designates them with the name iTemp.
8491 The compiler can be made to dump a human readable form of the code generated
8492 by using the ---dumpraw option.
8495 This phase does the bulk of the standard optimizations and is also MCU independe
8497 This phase can be broken down into several sub-phases:
8501 Break down intermediate code (iCode) into basic blocks.
8503 Do control flow & data flow analysis on the basic blocks.
8505 Do local common subexpression elimination, then global subexpression elimination
8507 Dead code elimination
8511 If loop optimizations caused any changes then do 'global subexpression eliminati
8512 on' and 'dead code elimination' again.
8515 This phase determines the live-ranges; by live range I mean those iTemp
8516 variables defined by the compiler that still survive after all the optimization
8518 Live range analysis is essential for register allocation, since these computati
8519 on determines which of these iTemps will be assigned to registers, and for
8523 Phase five is register allocation.
8524 There are two parts to this process.
8528 The first part I call 'register packing' (for lack of a better term).
8529 In this case several MCU specific expression folding is done to reduce
8534 The second part is more MCU independent and deals with allocating registers
8535 to the remaining live ranges.
8536 A lot of MCU specific code does creep into this phase because of the limited
8537 number of index registers available in the 8051.
8540 The Code generation phase is (unhappily), entirely MCU dependent and very
8541 little (if any at all) of this code can be reused for other MCU.
8542 However the scheme for allocating a homogenized assembler operand for each
8543 iCode operand may be reused.
8546 As mentioned in the optimization section the peep-hole optimizer is rule
8547 based system, which can reprogrammed for other MCUs.
8550 SDCDB - Source Level Debugger
8553 SDCC is distributed with a source level debugger.
8554 The debugger uses a command line interface, the command repertoire of the
8555 debugger has been kept as close to gdb (the GNU debugger) as possible.
8556 The configuration and build process is part of the standard compiler installati
8557 on, which also builds and installs the debugger in the target directory
8558 specified during configuration.
8559 The debugger allows you debug BOTH at the C source and at the ASM source
8563 Compiling for Debugging
8568 debug option must be specified for all files for which debug information
8570 The complier generates a .cdb file for each of these files.
8571 The linker updates the .cdb file with the address information.
8572 This .cdb is used by the debugger.
8575 How the Debugger Works
8578 When the ---debug option is specified the compiler generates extra symbol
8579 information some of which are put into the the assembler source and some
8580 are put into the .cdb file, the linker updates the .cdb file with the address
8581 information for the symbols.
8582 The debugger reads the symbolic information generated by the compiler &
8583 the address information generated by the linker.
8584 It uses the SIMULATOR (Daniel's S51) to execute the program, the program
8585 execution is controlled by the debugger.
8586 When a command is issued for the debugger, it translates it into appropriate
8587 commands for the simulator.
8590 Starting the Debugger
8593 The debugger can be started using the following command line.
8594 (Assume the file you are debugging has the file name foo).
8608 The debugger will look for the following files.
8611 foo.c - the source file.
8614 foo.cdb - the debugger symbol information file.
8617 foo.ihx - the intel hex format object file.
8620 Command Line Options.
8623 ---directory=<source file directory> this option can used to specify the
8624 directory search list.
8625 The debugger will look into the directory list specified for source, cdb
8627 The items in the directory list must be separated by ':', e.g.
8628 if the source files can be in the directories /home/src1 and /home/src2,
8629 the ---directory option should be ---directory=/home/src1:/home/src2.
8630 Note there can be no spaces in the option.
8634 -cd <directory> - change to the <directory>.
8637 -fullname - used by GUI front ends.
8640 -cpu <cpu-type> - this argument is passed to the simulator please see the
8641 simulator docs for details.
8644 -X <Clock frequency > this options is passed to the simulator please see
8645 the simulator docs for details.
8648 -s <serial port file> passed to simulator see the simulator docs for details.
8651 -S <serial in,out> passed to simulator see the simulator docs for details.
8657 As mention earlier the command interface for the debugger has been deliberately
8658 kept as close the GNU debugger gdb, as possible.
8659 This will help the integration with existing graphical user interfaces
8660 (like ddd, xxgdb or xemacs) existing for the GNU debugger.
8661 \layout Subsubsection
8663 break [line | file:line | function | file:function]
8666 Set breakpoint at specified line or function:
8675 sdcdb>break foo.c:100
8679 sdcdb>break foo.c:funcfoo
8680 \layout Subsubsection
8682 clear [line | file:line | function | file:function ]
8685 Clear breakpoint at specified line or function:
8694 sdcdb>clear foo.c:100
8698 sdcdb>clear foo.c:funcfoo
8699 \layout Subsubsection
8704 Continue program being debugged, after breakpoint.
8705 \layout Subsubsection
8710 Execute till the end of the current function.
8711 \layout Subsubsection
8716 Delete breakpoint number 'n'.
8717 If used without any option clear ALL user defined break points.
8718 \layout Subsubsection
8720 info [break | stack | frame | registers ]
8723 info break - list all breakpoints
8726 info stack - show the function call stack.
8729 info frame - show information about the current execution frame.
8732 info registers - show content of all registers.
8733 \layout Subsubsection
8738 Step program until it reaches a different source line.
8739 \layout Subsubsection
8744 Step program, proceeding through subroutine calls.
8745 \layout Subsubsection
8750 Start debugged program.
8751 \layout Subsubsection
8756 Print type information of the variable.
8757 \layout Subsubsection
8762 print value of variable.
8763 \layout Subsubsection
8768 load the given file name.
8769 Note this is an alternate method of loading file for debugging.
8770 \layout Subsubsection
8775 print information about current frame.
8776 \layout Subsubsection
8781 Toggle between C source & assembly source.
8782 \layout Subsubsection
8787 Send the string following '!' to the simulator, the simulator response is
8789 Note the debugger does not interpret the command being sent to the simulator,
8790 so if a command like 'go' is sent the debugger can loose its execution
8791 context and may display incorrect values.
8792 \layout Subsubsection
8799 My name is Bobby Brown"
8802 Interfacing with XEmacs.
8805 Two files (in emacs lisp) are provided for the interfacing with XEmacs,
8806 sdcdb.el and sdcdbsrc.el.
8807 These two files can be found in the $(prefix)/bin directory after the installat
8809 These files need to be loaded into XEmacs for the interface to work.
8810 This can be done at XEmacs startup time by inserting the following into
8811 your '.xemacs' file (which can be found in your HOME directory):
8817 (load-file sdcdbsrc.el)
8823 .xemacs is a lisp file so the () around the command is REQUIRED.
8824 The files can also be loaded dynamically while XEmacs is running, set the
8825 environment variable 'EMACSLOADPATH' to the installation bin directory
8826 (<installdir>/bin), then enter the following command ESC-x load-file sdcdbsrc.
8827 To start the interface enter the following command:
8841 You will prompted to enter the file name to be debugged.
8846 The command line options that are passed to the simulator directly are bound
8847 to default values in the file sdcdbsrc.el.
8848 The variables are listed below, these values maybe changed as required.
8851 sdcdbsrc-cpu-type '51
8854 sdcdbsrc-frequency '11059200
8860 The following is a list of key mapping for the debugger interface.
8868 ;; Current Listing ::
8885 binding\SpecialChar ~
8924 ------\SpecialChar ~
8964 sdcdb-next-from-src\SpecialChar ~
8990 sdcdb-back-from-src\SpecialChar ~
9016 sdcdb-cont-from-src\SpecialChar ~
9026 SDCDB continue command
9042 sdcdb-step-from-src\SpecialChar ~
9068 sdcdb-whatis-c-sexp\SpecialChar ~
9078 SDCDB ptypecommand for data at
9142 sdcdbsrc-delete\SpecialChar ~
9156 SDCDB Delete all breakpoints if no arg
9204 given or delete arg (C-u arg x)
9220 sdcdbsrc-frame\SpecialChar ~
9235 SDCDB Display current frame if no arg,
9284 given or display frame arg
9349 sdcdbsrc-goto-sdcdb\SpecialChar ~
9359 Goto the SDCDB output buffer
9375 sdcdb-print-c-sexp\SpecialChar ~
9386 SDCDB print command for data at
9450 sdcdbsrc-goto-sdcdb\SpecialChar ~
9460 Goto the SDCDB output buffer
9476 sdcdbsrc-mode\SpecialChar ~
9492 Toggles Sdcdbsrc mode (turns it off)
9496 ;; C-c C-f\SpecialChar ~
9504 sdcdb-finish-from-src\SpecialChar ~
9512 SDCDB finish command
9516 ;; C-x SPC\SpecialChar ~
9524 sdcdb-break\SpecialChar ~
9542 Set break for line with point
9544 ;; ESC t\SpecialChar ~
9554 sdcdbsrc-mode\SpecialChar ~
9570 Toggle Sdcdbsrc mode
9572 ;; ESC m\SpecialChar ~
9582 sdcdbsrc-srcmode\SpecialChar ~
9606 The Z80 and gbz80 port
9609 SDCC can target both the Zilog Z80 and the Nintendo Gameboy's Z80-like gbz80.
9610 The port is incomplete - long support is incomplete (mul, div and mod are
9611 unimplimented), and both float and bitfield support is missing.
9612 Apart from that the code generated is correct.
9615 As always, the code is the authoritave reference - see z80/ralloc.c and z80/gen.c.
9616 The stack frame is similar to that generated by the IAR Z80 compiler.
9617 IX is used as the base pointer, HL is used as a temporary register, and
9618 BC and DE are available for holding varibles.
9619 IY is currently unusued.
9620 Return values are stored in HL.
9621 One bad side effect of using IX as the base pointer is that a functions
9622 stack frame is limited to 127 bytes - this will be fixed in a later version.
9628 SDCC has grown to be a large project.
9629 The compiler alone (without the preprocessor, assembler and linker) is
9630 about 40,000 lines of code (blank stripped).
9631 The open source nature of this project is a key to its continued growth
9633 You gain the benefit and support of many active software developers and
9635 Is SDCC perfect? No, that's why we need your help.
9636 The developers take pride in fixing reported bugs.
9637 You can help by reporting the bugs and helping other SDCC users.
9638 There are lots of ways to contribute, and we encourage you to take part
9639 in making SDCC a great software package.
9645 Send an email to the mailing list at 'user-sdcc@sdcc.sourceforge.net' or 'devel-sd
9646 cc@sdcc.sourceforge.net'.
9647 Bugs will be fixed ASAP.
9648 When reporting a bug, it is very useful to include a small test program
9649 which reproduces the problem.
9650 If you can isolate the problem by looking at the generated assembly code,
9651 this can be very helpful.
9652 Compiling your program with the ---dumpall option can sometimes be useful
9653 in locating optimization problems.
9659 The anatomy of the compiler
9664 This is an excerpt from an atricle published in Circuit Cellar MagaZine
9666 It's a little outdated (the compiler is much more efficient now and user/devell
9667 oper friendly), but pretty well exposes the guts of it all.
9673 The current version of SDCC can generate code for Intel 8051 and Z80 MCU.
9674 It is fairly easy to retarget for other 8-bit MCU.
9675 Here we take a look at some of the internals of the compiler.
9682 Parsing the input source file and creating an AST (Annotated Syntax Tree).
9683 This phase also involves propagating types (annotating each node of the
9684 parse tree with type information) and semantic analysis.
9685 There are some MCU specific parsing rules.
9686 For example the storage classes, the extended storage classes are MCU specific
9687 while there may be a xdata storage class for 8051 there is no such storage
9688 class for z80 or Atmel AVR.
9689 SDCC allows MCU specific storage class extensions, i.e.
9690 xdata will be treated as a storage class specifier when parsing 8051 C
9691 code but will be treated as a C identifier when parsing z80 or ATMEL AVR
9698 Intermediate code generation.
9699 In this phase the AST is broken down into three-operand form (iCode).
9700 These three operand forms are represented as doubly linked lists.
9701 ICode is the term given to the intermediate form generated by the compiler.
9702 ICode example section shows some examples of iCode generated for some simple
9709 Bulk of the target independent optimizations is performed in this phase.
9710 The optimizations include constant propagation, common sub-expression eliminati
9711 on, loop invariant code movement, strength reduction of loop induction variables
9712 and dead-code elimination.
9718 During intermediate code generation phase, the compiler assumes the target
9719 machine has infinite number of registers and generates a lot of temporary
9721 The live range computation determines the lifetime of each of these compiler-ge
9722 nerated temporaries.
9723 A picture speaks a thousand words.
9724 ICode example sections show the live range annotations for each of the
9726 It is important to note here, each iCode is assigned a number in the order
9727 of its execution in the function.
9728 The live ranges are computed in terms of these numbers.
9729 The from number is the number of the iCode which first defines the operand
9730 and the to number signifies the iCode which uses this operand last.
9736 The register allocation determines the type and number of registers needed
9738 In most MCUs only a few registers can be used for indirect addressing.
9739 In case of 8051 for example the registers R0 & R1 can be used to indirectly
9740 address the internal ram and DPTR to indirectly address the external ram.
9741 The compiler will try to allocate the appropriate register to pointer variables
9743 ICode example section shows the operands annotated with the registers assigned
9745 The compiler will try to keep operands in registers as much as possible;
9746 there are several schemes the compiler uses to do achieve this.
9747 When the compiler runs out of registers the compiler will check to see
9748 if there are any live operands which is not used or defined in the current
9749 basic block being processed, if there are any found then it will push that
9750 operand and use the registers in this block, the operand will then be popped
9751 at the end of the basic block.
9755 There are other MCU specific considerations in this phase.
9756 Some MCUs have an accumulator; very short-lived operands could be assigned
9757 to the accumulator instead of general-purpose register.
9763 Figure II gives a table of iCode operations supported by the compiler.
9764 The code generation involves translating these operations into corresponding
9765 assembly code for the processor.
9766 This sounds overly simple but that is the essence of code generation.
9767 Some of the iCode operations are generated on a MCU specific manner for
9768 example, the z80 port does not use registers to pass parameters so the
9769 SEND and RECV iCode operations will not be generated, and it also does
9770 not support JUMPTABLES.
9777 <Where is Figure II ?>
9783 This section shows some details of iCode.
9784 The example C code does not do anything useful; it is used as an example
9785 to illustrate the intermediate code generated by the compiler.
9798 /* This function does nothing useful.
9805 for the purpose of explaining iCode */
9808 short function (data int *x)
9816 short i=10; /* dead initialization eliminated */
9821 short sum=10; /* dead initialization eliminated */
9834 while (*x) *x++ = *p++;
9848 /* compiler detects i,j to be induction variables */
9852 for (i = 0, j = 10 ; i < 10 ; i++, j---) {
9864 mul += i * 3; /* this multiplication remains */
9870 gint += j * 3;/* this multiplication changed to addition */
9887 In addition to the operands each iCode contains information about the filename
9888 and line it corresponds to in the source file.
9889 The first field in the listing should be interpreted as follows:
9894 Filename(linenumber: iCode Execution sequence number : ICode hash table
9895 key : loop depth of the iCode).
9900 Then follows the human readable form of the ICode operation.
9901 Each operand of this triplet form can be of three basic types a) compiler
9902 generated temporary b) user defined variable c) a constant value.
9903 Note that local variables and parameters are replaced by compiler generated
9905 Live ranges are computed only for temporaries (i.e.
9906 live ranges are not computed for global variables).
9907 Registers are allocated for temporaries only.
9908 Operands are formatted in the following manner:
9913 Operand Name [lr live-from : live-to ] { type information } [ registers
9919 As mentioned earlier the live ranges are computed in terms of the execution
9920 sequence number of the iCodes, for example
9922 the iTemp0 is live from (i.e.
9923 first defined in iCode with execution sequence number 3, and is last used
9924 in the iCode with sequence number 5).
9925 For induction variables such as iTemp21 the live range computation extends
9926 the lifetime from the start to the end of the loop.
9928 The register allocator used the live range information to allocate registers,
9929 the same registers may be used for different temporaries if their live
9930 ranges do not overlap, for example r0 is allocated to both iTemp6 and to
9931 iTemp17 since their live ranges do not overlap.
9932 In addition the allocator also takes into consideration the type and usage
9933 of a temporary, for example itemp6 is a pointer to near space and is used
9934 as to fetch data from (i.e.
9935 used in GET_VALUE_AT_ADDRESS) so it is allocated a pointer registers (r0).
9936 Some short lived temporaries are allocated to special registers which have
9937 meaning to the code generator e.g.
9938 iTemp13 is allocated to a pseudo register CC which tells the back end that
9939 the temporary is used only for a conditional jump the code generation makes
9940 use of this information to optimize a compare and jump ICode.
9942 There are several loop optimizations performed by the compiler.
9943 It can detect induction variables iTemp21(i) and iTemp23(j).
9944 Also note the compiler does selective strength reduction, i.e.
9945 the multiplication of an induction variable in line 18 (gint = j * 3) is
9946 changed to addition, a new temporary iTemp17 is allocated and assigned
9947 a initial value, a constant 3 is then added for each iteration of the loop.
9948 The compiler does not change the multiplication in line 17 however since
9949 the processor does support an 8 * 8 bit multiplication.
9951 Note the dead code elimination optimization eliminated the dead assignments
9952 in line 7 & 8 to I and sum respectively.
9959 Sample.c (5:1:0:0) _entry($9) :
9964 Sample.c(5:2:1:0) proc _function [lr0:0]{function short}
9969 Sample.c(11:3:2:0) iTemp0 [lr3:5]{_near * int}[r2] = recv
9974 Sample.c(11:4:53:0) preHeaderLbl0($11) :
9979 Sample.c(11:5:55:0) iTemp6 [lr5:16]{_near * int}[r0] := iTemp0 [lr3:5]{_near
9985 Sample.c(11:6:5:1) _whilecontinue_0($1) :
9990 Sample.c(11:7:7:1) iTemp4 [lr7:8]{int}[r2 r3] = @[iTemp6 [lr5:16]{_near *
9996 Sample.c(11:8:8:1) if iTemp4 [lr7:8]{int}[r2 r3] == 0 goto _whilebreak_0($3)
10001 Sample.c(11:9:14:1) iTemp7 [lr9:13]{_far * int}[DPTR] := _p [lr0:0]{_far
10007 Sample.c(11:10:15:1) _p [lr0:0]{_far * int} = _p [lr0:0]{_far * int} + 0x2
10013 Sample.c(11:13:18:1) iTemp10 [lr13:14]{int}[r2 r3] = @[iTemp7 [lr9:13]{_far
10019 Sample.c(11:14:19:1) *(iTemp6 [lr5:16]{_near * int}[r0]) := iTemp10 [lr13:14]{int
10025 Sample.c(11:15:12:1) iTemp6 [lr5:16]{_near * int}[r0] = iTemp6 [lr5:16]{_near
10026 * int}[r0] + 0x2 {short}
10031 Sample.c(11:16:20:1) goto _whilecontinue_0($1)
10036 Sample.c(11:17:21:0)_whilebreak_0($3) :
10041 Sample.c(12:18:22:0) iTemp2 [lr18:40]{short}[r2] := 0x0 {short}
10046 Sample.c(13:19:23:0) iTemp11 [lr19:40]{short}[r3] := 0x0 {short}
10051 Sample.c(15:20:54:0)preHeaderLbl1($13) :
10056 Sample.c(15:21:56:0) iTemp21 [lr21:38]{short}[r4] := 0x0 {short}
10061 Sample.c(15:22:57:0) iTemp23 [lr22:38]{int}[r5 r6] := 0xa {int}
10066 Sample.c(15:23:58:0) iTemp17 [lr23:38]{int}[r7 r0] := 0x1e {int}
10071 Sample.c(15:24:26:1)_forcond_0($4) :
10076 Sample.c(15:25:27:1) iTemp13 [lr25:26]{char}[CC] = iTemp21 [lr21:38]{short}[r4]
10082 Sample.c(15:26:28:1) if iTemp13 [lr25:26]{char}[CC] == 0 goto _forbreak_0($7)
10087 Sample.c(16:27:31:1) iTemp2 [lr18:40]{short}[r2] = iTemp2 [lr18:40]{short}[r2]
10088 + ITemp21 [lr21:38]{short}[r4]
10093 Sample.c(17:29:33:1) iTemp15 [lr29:30]{short}[r1] = iTemp21 [lr21:38]{short}[r4]
10099 Sample.c(17:30:34:1) iTemp11 [lr19:40]{short}[r3] = iTemp11 [lr19:40]{short}[r3]
10100 + iTemp15 [lr29:30]{short}[r1]
10105 Sample.c(18:32:36:1:1) iTemp17 [lr23:38]{int}[r7 r0]= iTemp17 [lr23:38]{int}[r7
10111 Sample.c(18:33:37:1) _gint [lr0:0]{int} = _gint [lr0:0]{int} + iTemp17 [lr23:38]{
10117 Sample.c(15:36:42:1) iTemp21 [lr21:38]{short}[r4] = iTemp21 [lr21:38]{short}[r4]
10123 Sample.c(15:37:45:1) iTemp23 [lr22:38]{int}[r5 r6]= iTemp23 [lr22:38]{int}[r5
10129 Sample.c(19:38:47:1) goto _forcond_0($4)
10134 Sample.c(19:39:48:0)_forbreak_0($7) :
10139 Sample.c(20:40:49:0) iTemp24 [lr40:41]{short}[DPTR] = iTemp2 [lr18:40]{short}[r2]
10140 + ITemp11 [lr19:40]{short}[r3]
10145 Sample.c(20:41:50:0) ret iTemp24 [lr40:41]{short}
10150 Sample.c(20:42:51:0)_return($8) :
10155 Sample.c(20:43:52:0) eproc _function [lr0:0]{ ia0 re0 rm0}{function short}
10161 Finally the code generated for this function:
10202 ; ----------------------------------------------
10207 ; function function
10212 ; ----------------------------------------------
10222 ; iTemp0 [lr3:5]{_near * int}[r2] = recv
10234 ; iTemp6 [lr5:16]{_near * int}[r0] := iTemp0 [lr3:5]{_near * int}[r2]
10246 ;_whilecontinue_0($1) :
10256 ; iTemp4 [lr7:8]{int}[r2 r3] = @[iTemp6 [lr5:16]{_near * int}[r0]]
10261 ; if iTemp4 [lr7:8]{int}[r2 r3] == 0 goto _whilebreak_0($3)
10320 ; iTemp7 [lr9:13]{_far * int}[DPTR] := _p [lr0:0]{_far * int}
10339 ; _p [lr0:0]{_far * int} = _p [lr0:0]{_far * int} + 0x2 {short}
10386 ; iTemp10 [lr13:14]{int}[r2 r3] = @[iTemp7 [lr9:13]{_far * int}[DPTR]]
10426 ; *(iTemp6 [lr5:16]{_near * int}[r0]) := iTemp10 [lr13:14]{int}[r2 r3]
10452 ; iTemp6 [lr5:16]{_near * int}[r0] =
10457 ; iTemp6 [lr5:16]{_near * int}[r0] +
10474 ; goto _whilecontinue_0($1)
10486 ; _whilebreak_0($3) :
10496 ; iTemp2 [lr18:40]{short}[r2] := 0x0 {short}
10508 ; iTemp11 [lr19:40]{short}[r3] := 0x0 {short}
10520 ; iTemp21 [lr21:38]{short}[r4] := 0x0 {short}
10532 ; iTemp23 [lr22:38]{int}[r5 r6] := 0xa {int}
10551 ; iTemp17 [lr23:38]{int}[r7 r0] := 0x1e {int}
10580 ; iTemp13 [lr25:26]{char}[CC] = iTemp21 [lr21:38]{short}[r4] < 0xa {short}
10585 ; if iTemp13 [lr25:26]{char}[CC] == 0 goto _forbreak_0($7)
10630 ; iTemp2 [lr18:40]{short}[r2] = iTemp2 [lr18:40]{short}[r2] +
10635 ; iTemp21 [lr21:38]{short}[r4]
10661 ; iTemp15 [lr29:30]{short}[r1] = iTemp21 [lr21:38]{short}[r4] * 0x3 {short}
10694 ; iTemp11 [lr19:40]{short}[r3] = iTemp11 [lr19:40]{short}[r3] +
10699 ; iTemp15 [lr29:30]{short}[r1]
10718 ; iTemp17 [lr23:38]{int}[r7 r0]= iTemp17 [lr23:38]{int}[r7 r0]- 0x3 {short}
10765 ; _gint [lr0:0]{int} = _gint [lr0:0]{int} + iTemp17 [lr23:38]{int}[r7 r0]
10812 ; iTemp21 [lr21:38]{short}[r4] = iTemp21 [lr21:38]{short}[r4] + 0x1 {short}
10824 ; iTemp23 [lr22:38]{int}[r5 r6]= iTemp23 [lr22:38]{int}[r5 r6]- 0x1 {short}
10838 cjne r5,#0xff,00104$
10850 ; goto _forcond_0($4)
10862 ; _forbreak_0($7) :
10872 ; ret iTemp24 [lr40:41]{short}
10915 A few words about basic block successors, predecessors and dominators
10918 Successors are basic blocks that might execute after this basic block.
10920 Predecessors are basic blocks that might execute before reaching this basic
10923 Dominators are basic blocks that WILL execute before reaching this basic
10949 a) succList of [BB2] = [BB4], of [BB3] = [BB4], of [BB1] = [BB2,BB3]
10952 b) predList of [BB2] = [BB1], of [BB3] = [BB1], of [BB4] = [BB2,BB3]
10955 c) domVect of [BB4] = BB1 ...
10956 here we are not sure if BB2 or BB3 was executed but we are SURE that BB1
10964 \begin_inset LatexCommand \url{http://sdcc.sourceforge.net#Who}
10974 Thanks to all the other volunteer developers who have helped with coding,
10975 testing, web-page creation, distribution sets, etc.
10976 You know who you are :-)
10983 This document was initially written by Sandeep Dutta
10986 All product names mentioned herein may be trademarks of their respective
10992 \begin_inset LatexCommand \printindex{}