1 \input texinfo @c -*-Texinfo-*-
2 @c Copyright 1991, 1992, 1993, 1994, 1995, 1996, 1997, 1998, 1999, 2000,
4 @c Free Software Foundation, Inc.
5 @c UPDATE!! On future updates--
6 @c (1) check for new machine-dep cmdline options in
7 @c md_parse_option definitions in config/tc-*.c
8 @c (2) for platform-specific directives, examine md_pseudo_op
10 @c (3) for object-format specific directives, examine obj_pseudo_op
12 @c (4) portable directives in potable[] in read.c
16 @macro gcctabopt{body}
19 @c defaults, config file may override:
22 @include asconfig.texi
27 @c Configure for the generation of man pages
63 @c common OR combinations of conditions
83 @set abnormal-separator
87 @settitle Using @value{AS}
90 @settitle Using @value{AS} (@value{TARGET})
92 @setchapternewpage odd
97 @c WARE! Some of the machine-dependent sections contain tables of machine
98 @c instructions. Except in multi-column format, these tables look silly.
99 @c Unfortunately, Texinfo doesn't have a general-purpose multi-col format, so
100 @c the multi-col format is faked within @example sections.
102 @c Again unfortunately, the natural size that fits on a page, for these tables,
103 @c is different depending on whether or not smallbook is turned on.
104 @c This matters, because of order: text flow switches columns at each page
107 @c The format faked in this source works reasonably well for smallbook,
108 @c not well for the default large-page format. This manual expects that if you
109 @c turn on @smallbook, you will also uncomment the "@set SMALL" to enable the
110 @c tables in question. You can turn on one without the other at your
111 @c discretion, of course.
114 @c the insn tables look just as silly in info files regardless of smallbook,
115 @c might as well show 'em anyways.
121 * As: (as). The GNU assembler.
122 * Gas: (as). The GNU assembler.
131 This file documents the GNU Assembler "@value{AS}".
133 @c man begin COPYRIGHT
134 Copyright (C) 1991, 92, 93, 94, 95, 96, 97, 98, 99, 2000, 2001, 2002 Free Software Foundation, Inc.
136 Permission is granted to copy, distribute and/or modify this document
137 under the terms of the GNU Free Documentation License, Version 1.1
138 or any later version published by the Free Software Foundation;
139 with no Invariant Sections, with no Front-Cover Texts, and with no
140 Back-Cover Texts. A copy of the license is included in the
141 section entitled "GNU Free Documentation License".
146 Permission is granted to process this file through Tex and print the
147 results, provided the printed document carries copying permission
148 notice identical to this one except for the removal of this paragraph
149 (this paragraph not being relevant to the printed manual).
155 @title Using @value{AS}
156 @subtitle The @sc{gnu} Assembler
158 @subtitle for the @value{TARGET} family
161 @subtitle Version @value{VERSION}
164 The Free Software Foundation Inc. thanks The Nice Computer
165 Company of Australia for loaning Dean Elsner to write the
166 first (Vax) version of @command{as} for Project @sc{gnu}.
167 The proprietors, management and staff of TNCCA thank FSF for
168 distracting the boss while they got some work
171 @author Dean Elsner, Jay Fenlason & friends
175 \hfill {\it Using {\tt @value{AS}}}\par
176 \hfill Edited by Cygnus Support\par
178 %"boxit" macro for figures:
179 %Modified from Knuth's ``boxit'' macro from TeXbook (answer to exercise 21.3)
180 \gdef\boxit#1#2{\vbox{\hrule\hbox{\vrule\kern3pt
181 \vbox{\parindent=0pt\parskip=0pt\hsize=#1\kern3pt\strut\hfil
182 #2\hfil\strut\kern3pt}\kern3pt\vrule}\hrule}}%box with visible outline
183 \gdef\ibox#1#2{\hbox to #1{#2\hfil}\kern8pt}% invisible box
186 @vskip 0pt plus 1filll
187 Copyright @copyright{} 1991, 92, 93, 94, 95, 96, 97, 98, 99, 2000, 2001, 2002 Free Software Foundation, Inc.
189 Permission is granted to copy, distribute and/or modify this document
190 under the terms of the GNU Free Documentation License, Version 1.1
191 or any later version published by the Free Software Foundation;
192 with no Invariant Sections, with no Front-Cover Texts, and with no
193 Back-Cover Texts. A copy of the license is included in the
194 section entitled "GNU Free Documentation License".
200 @top Using @value{AS}
202 This file is a user guide to the @sc{gnu} assembler @command{@value{AS}} version
205 This version of the file describes @command{@value{AS}} configured to generate
206 code for @value{TARGET} architectures.
209 This document is distributed under the terms of the GNU Free
210 Documentation License. A copy of the license is included in the
211 section entitled "GNU Free Documentation License".
214 * Overview:: Overview
215 * Invoking:: Command-Line Options
217 * Sections:: Sections and Relocation
219 * Expressions:: Expressions
220 * Pseudo Ops:: Assembler Directives
221 * Machine Dependencies:: Machine Dependent Features
222 * Reporting Bugs:: Reporting Bugs
223 * Acknowledgements:: Who Did What
224 * GNU Free Documentation License:: GNU Free Documentation License
232 This manual is a user guide to the @sc{gnu} assembler @command{@value{AS}}.
234 This version of the manual describes @command{@value{AS}} configured to generate
235 code for @value{TARGET} architectures.
239 @cindex invocation summary
240 @cindex option summary
241 @cindex summary of options
242 Here is a brief summary of how to invoke @command{@value{AS}}. For details,
243 @pxref{Invoking,,Comand-Line Options}.
245 @c man title AS the portable GNU assembler.
249 gcc(1), ld(1), and the Info entries for @file{binutils} and @file{ld}.
253 @c We don't use deffn and friends for the following because they seem
254 @c to be limited to one line for the header.
256 @c man begin SYNOPSIS
257 @value{AS} [@b{-a}[@b{cdhlns}][=@var{file}]] [@b{-D}] [@b{--defsym} @var{sym}=@var{val}]
258 [@b{-f}] [@b{--gstabs}] [@b{--gdwarf2}] [@b{--help}] [@b{-I} @var{dir}]
259 [@b{-J}] [@b{-K}] [@b{-L}]
260 [@b{--listing-lhs-width}=@var{NUM}] [@b{--listing-lhs-width2}=@var{NUM}]
261 [@b{--listing-rhs-width}=@var{NUM}] [@b{--listing-cont-lines}=@var{NUM}]
262 [@b{--keep-locals}] [@b{-o} @var{objfile}] [@b{-R}] [@b{--statistics}] [@b{-v}]
263 [@b{-version}] [@b{--version}] [@b{-W}] [@b{--warn}] [@b{--fatal-warnings}]
264 [@b{-w}] [@b{-x}] [@b{-Z}] [@b{--target-help}] [@var{target-options}]
265 [@b{--}|@var{files} @dots{}]
267 @c Target dependent options are listed below. Keep the list sorted.
268 @c Add an empty line for separation.
270 @c am29k has no machine-dependent assembler options
274 @emph{Target Alpha options:}
276 [@b{-mdebug} | @b{-no-mdebug}]
277 [@b{-relax}] [@b{-g}] [@b{-G@var{size}}]
278 [@b{-F}] [@b{-32addr}]
282 @emph{Target ARC options:}
288 @emph{Target ARM options:}
289 @c Don't document the deprecated options
290 [@b{-mcpu}=@var{processor}[+@var{extension}@dots{}]]
291 [@b{-march}=@var{architecture}[+@var{extension}@dots{}]]
292 [@b{-mfpu}=@var{floating-point-fromat}]
295 [@b{-mapcs-32}|@b{-mapcs-26}|@b{-mapcs-float}|
296 @b{-mapcs-reentrant}]
297 [@b{-mthumb-interwork}] [@b{-moabi}] [@b{-k}]
301 @emph{Target CRIS options:}
302 [@b{--underscore} | @b{--no-underscore}]
304 [@b{--emulation=criself} | @b{--emulation=crisaout}]
305 @c Deprecated -- deliberately not documented.
310 @emph{Target D10V options:}
315 @emph{Target D30V options:}
316 [@b{-O}|@b{-n}|@b{-N}]
319 @c Hitachi family chips have no machine-dependent assembler options
322 @c HPPA has no machine-dependent assembler options (yet).
326 @emph{Target i386 options:}
331 @emph{Target i960 options:}
332 @c see md_parse_option in tc-i960.c
333 [@b{-ACA}|@b{-ACA_A}|@b{-ACB}|@b{-ACC}|@b{-AKA}|@b{-AKB}|
335 [@b{-b}] [@b{-no-relax}]
339 @emph{Target IA-64 options:}
340 [@b{-mconstant-gp}|@b{-mauto-pic}]
341 [@b{-milp32}|@b{-milp64}|@b{-mlp64}|@b{-mp64}]
343 [@b{-x}|@b{-xexplicit}] [@b{-xauto}] [@b{-xdebug}]
347 @emph{Target M32R options:}
348 [@b{--m32rx}|@b{--[no-]warn-explicit-parallel-conflicts}|
353 @emph{Target M680X0 options:}
354 [@b{-l}] [@b{-m68000}|@b{-m68010}|@b{-m68020}|@dots{}]
358 @emph{Target M68HC11 options:}
359 [@b{-m68hc11}|@b{-m68hc12}]
360 [@b{--force-long-branchs}] [@b{--short-branchs}]
361 [@b{--strict-direct-mode}] [@b{--print-insn-syntax}]
362 [@b{--print-opcodes}] [@b{--generate-example}]
366 @emph{Target MCORE options:}
367 [@b{-jsri2bsr}] [@b{-sifilter}] [@b{-relax}]
368 [@b{-mcpu=[210|340]}]
372 @emph{Target MIPS options:}
373 [@b{-nocpp}] [@b{-EL}] [@b{-EB}] [@b{-G} @var{num}] [@b{-mcpu}=@var{CPU} ]
374 [@b{-mips1}] [@b{-mips2}] [@b{-mips3}] [@b{-mips4}] [@b{-mips5}]
375 [@b{-mips32}] [@b{-mips64}]
376 [@b{-m4650}] [@b{-no-m4650}]
377 [@b{-mips3d}] [@b{-no-mips3d}]
378 [@b{-mdmx}] [@b{-no-mdmx}]
379 [@b{--trap}] [@b{--break}] [@b{-n}]
380 [@b{--emulation}=@var{name} ]
384 @emph{Target MMIX options:}
385 [@b{--fixed-special-register-names}] [@b{--globalize-symbols}]
386 [@b{--gnu-syntax}] [@b{--relax}] [@b{--no-predefined-symbols}]
387 [@b{--no-expand}] [@b{--no-merge-gregs}] [@b{-x}]
388 [@b{--linker-allocated-gregs}]
392 @emph{Target PDP11 options:}
393 [@b{-mpic}|@b{-mno-pic}] [@b{-mall}] [@b{-mno-extensions}]
394 [@b{-m}@var{extension}|@b{-mno-}@var{extension}]
395 [@b{-m}@var{cpu}] [@b{-m}@var{machine}]
399 @emph{Target picoJava options:}
404 @emph{Target PowerPC options:}
405 [@b{-mpwrx}|@b{-mpwr2}|@b{-mpwr}|@b{-m601}|@b{-mppc}|@b{-mppc32}|@b{-m603}|@b{-m604}|
406 @b{-m403}|@b{-m405}|@b{-mppc64}|@b{-m620}|@b{-mppc64bridge}|@b{-mbooke}|
407 @b{-mbooke32}|@b{-mbooke64}]
408 [@b{-mcom}|@b{-many}|@b{-maltivec}] [@b{-memb}]
409 [@b{-mregnames}|@b{-mno-regnames}]
410 [@b{-mrelocatable}|@b{-mrelocatable-lib}]
411 [@b{-mlittle}|@b{-mlittle-endian}|@b{-mbig}|@b{-mbig-endian}]
412 [@b{-msolaris}|@b{-mno-solaris}]
416 @emph{Target SPARC options:}
417 @c The order here is important. See c-sparc.texi.
418 [@b{-Av6}|@b{-Av7}|@b{-Av8}|@b{-Asparclet}|@b{-Asparclite}
419 @b{-Av8plus}|@b{-Av8plusa}|@b{-Av9}|@b{-Av9a}]
420 [@b{-xarch=v8plus}|@b{-xarch=v8plusa}] [@b{-bump}]
425 @emph{Target TIC54X options:}
426 [@b{-mcpu=54[123589]}|@b{-mcpu=54[56]lp}] [@b{-mfar-mode}|@b{-mf}]
427 [@b{-merrors-to-file} @var{<filename>}|@b{-me} @var{<filename>}]
430 @c Z8000 has no machine-dependent assembler options
439 Turn on listings, in any of a variety of ways:
443 omit false conditionals
446 omit debugging directives
449 include high-level source
455 include macro expansions
458 omit forms processing
464 set the name of the listing file
467 You may combine these options; for example, use @samp{-aln} for assembly
468 listing without forms processing. The @samp{=file} option, if used, must be
469 the last one. By itself, @samp{-a} defaults to @samp{-ahls}.
472 Ignored. This option is accepted for script compatibility with calls to
475 @item --defsym @var{sym}=@var{value}
476 Define the symbol @var{sym} to be @var{value} before assembling the input file.
477 @var{value} must be an integer constant. As in C, a leading @samp{0x}
478 indicates a hexadecimal value, and a leading @samp{0} indicates an octal value.
481 ``fast''---skip whitespace and comment preprocessing (assume source is
485 Generate stabs debugging information for each assembler line. This
486 may help debugging assembler code, if the debugger can handle it.
489 Generate DWARF2 debugging information for each assembler line. This
490 may help debugging assembler code, if the debugger can handle it. Note - this
491 option is only supported by some targets, not all of them.
494 Print a summary of the command line options and exit.
497 Print a summary of all target specific options and exit.
500 Add directory @var{dir} to the search list for @code{.include} directives.
503 Don't warn about signed overflow.
506 @ifclear DIFF-TBL-KLUGE
507 This option is accepted but has no effect on the @value{TARGET} family.
509 @ifset DIFF-TBL-KLUGE
510 Issue warnings when difference tables altered for long displacements.
515 Keep (in the symbol table) local symbols. On traditional a.out systems
516 these start with @samp{L}, but different systems have different local
519 @item --listing-lhs-width=@var{number}
520 Set the maximum width, in words, of the output data column for an assembler
521 listing to @var{number}.
523 @item --listing-lhs-width2=@var{number}
524 Set the maximum width, in words, of the output data column for continuation
525 lines in an assembler listing to @var{number}.
527 @item --listing-rhs-width=@var{number}
528 Set the maximum width of an input source line, as displayed in a listing, to
531 @item --listing-cont-lines=@var{number}
532 Set the maximum number of lines printed in a listing for a single line of input
535 @item -o @var{objfile}
536 Name the object-file output from @command{@value{AS}} @var{objfile}.
539 Fold the data section into the text section.
542 Print the maximum space (in bytes) and total time (in seconds) used by
545 @item --strip-local-absolute
546 Remove local absolute symbols from the outgoing symbol table.
550 Print the @command{as} version.
553 Print the @command{as} version and exit.
557 Suppress warning messages.
559 @item --fatal-warnings
560 Treat warnings as errors.
563 Don't suppress warning messages or treat them as errors.
572 Generate an object file even after errors.
574 @item -- | @var{files} @dots{}
575 Standard input, or source files to assemble.
580 The following options are available when @value{AS} is configured for
585 This option selects the core processor variant.
587 Select either big-endian (-EB) or little-endian (-EL) output.
592 The following options are available when @value{AS} is configured for the ARM
596 @item -mcpu=@var{processor}[+@var{extension}@dots{}]
597 Specify which ARM processor variant is the target.
598 @item -march=@var{architecture}[+@var{extension}@dots{}]
599 Specify which ARM architecture variant is used by the target.
600 @item -mfpu=@var{floating-point-format}
601 Select which Floating Point architecture is the target.
603 Enable Thumb only instruction decoding.
604 @item -mapcs-32 | -mapcs-26 | -mapcs-float | -mapcs-reentrant | -moabi
605 Select which procedure calling convention is in use.
607 Select either big-endian (-EB) or little-endian (-EL) output.
608 @item -mthumb-interwork
609 Specify that the code has been generated with interworking between Thumb and
612 Specify that PIC code has been generated.
617 See the info pages for documentation of the CRIS-specific options.
621 The following options are available when @value{AS} is configured for
624 @cindex D10V optimization
625 @cindex optimization, D10V
627 Optimize output by parallelizing instructions.
632 The following options are available when @value{AS} is configured for a D30V
635 @cindex D30V optimization
636 @cindex optimization, D30V
638 Optimize output by parallelizing instructions.
642 Warn when nops are generated.
644 @cindex D30V nops after 32-bit multiply
646 Warn when a nop after a 32-bit multiply instruction is generated.
651 The following options are available when @value{AS} is configured for the
652 Intel 80960 processor.
655 @item -ACA | -ACA_A | -ACB | -ACC | -AKA | -AKB | -AKC | -AMC
656 Specify which variant of the 960 architecture is the target.
659 Add code to collect statistics about branches taken.
662 Do not alter compare-and-branch instructions for long displacements;
669 The following options are available when @value{AS} is configured for the
670 Mitsubishi M32R series.
675 Specify which processor in the M32R family is the target. The default
676 is normally the M32R, but this option changes it to the M32RX.
678 @item --warn-explicit-parallel-conflicts or --Wp
679 Produce warning messages when questionable parallel constructs are
682 @item --no-warn-explicit-parallel-conflicts or --Wnp
683 Do not produce warning messages when questionable parallel constructs are
690 The following options are available when @value{AS} is configured for the
691 Motorola 68000 series.
696 Shorten references to undefined symbols, to one word instead of two.
698 @item -m68000 | -m68008 | -m68010 | -m68020 | -m68030
699 @itemx | -m68040 | -m68060 | -m68302 | -m68331 | -m68332
700 @itemx | -m68333 | -m68340 | -mcpu32 | -m5200
701 Specify what processor in the 68000 family is the target. The default
702 is normally the 68020, but this can be changed at configuration time.
704 @item -m68881 | -m68882 | -mno-68881 | -mno-68882
705 The target machine does (or does not) have a floating-point coprocessor.
706 The default is to assume a coprocessor for 68020, 68030, and cpu32. Although
707 the basic 68000 is not compatible with the 68881, a combination of the
708 two can be specified, since it's possible to do emulation of the
709 coprocessor instructions with the main processor.
711 @item -m68851 | -mno-68851
712 The target machine does (or does not) have a memory-management
713 unit coprocessor. The default is to assume an MMU for 68020 and up.
720 For details about the PDP-11 machine dependent features options,
721 see @ref{PDP-11-Options}.
724 @item -mpic | -mno-pic
725 Generate position-independent (or position-dependent) code. The
726 default is @option{-mpic}.
729 @itemx -mall-extensions
730 Enable all instruction set extensions. This is the default.
732 @item -mno-extensions
733 Disable all instruction set extensions.
735 @item -m@var{extension} | -mno-@var{extension}
736 Enable (or disable) a particular instruction set extension.
739 Enable the instruction set extensions supported by a particular CPU, and
740 disable all other extensions.
742 @item -m@var{machine}
743 Enable the instruction set extensions supported by a particular machine
744 model, and disable all other extensions.
750 The following options are available when @value{AS} is configured for
751 a picoJava processor.
755 @cindex PJ endianness
756 @cindex endianness, PJ
757 @cindex big endian output, PJ
759 Generate ``big endian'' format output.
761 @cindex little endian output, PJ
763 Generate ``little endian'' format output.
769 The following options are available when @value{AS} is configured for the
770 Motorola 68HC11 or 68HC12 series.
774 @item -m68hc11 | -m68hc12
775 Specify what processor is the target. The default is
776 defined by the configuration option when building the assembler.
778 @item --force-long-branchs
779 Relative branches are turned into absolute ones. This concerns
780 conditional branches, unconditional branches and branches to a
783 @item -S | --short-branchs
784 Do not turn relative branchs into absolute ones
785 when the offset is out of range.
787 @item --strict-direct-mode
788 Do not turn the direct addressing mode into extended addressing mode
789 when the instruction does not support direct addressing mode.
791 @item --print-insn-syntax
792 Print the syntax of instruction in case of error.
794 @item --print-opcodes
795 print the list of instructions with syntax and then exit.
797 @item --generate-example
798 print an example of instruction for each possible instruction and then exit.
799 This option is only useful for testing @command{@value{AS}}.
805 The following options are available when @command{@value{AS}} is configured
806 for the SPARC architecture:
809 @item -Av6 | -Av7 | -Av8 | -Asparclet | -Asparclite
810 @itemx -Av8plus | -Av8plusa | -Av9 | -Av9a
811 Explicitly select a variant of the SPARC architecture.
813 @samp{-Av8plus} and @samp{-Av8plusa} select a 32 bit environment.
814 @samp{-Av9} and @samp{-Av9a} select a 64 bit environment.
816 @samp{-Av8plusa} and @samp{-Av9a} enable the SPARC V9 instruction set with
817 UltraSPARC extensions.
819 @item -xarch=v8plus | -xarch=v8plusa
820 For compatibility with the Solaris v9 assembler. These options are
821 equivalent to -Av8plus and -Av8plusa, respectively.
824 Warn when the assembler switches to another architecture.
829 The following options are available when @value{AS} is configured for the 'c54x
834 Enable extended addressing mode. All addresses and relocations will assume
835 extended addressing (usually 23 bits).
836 @item -mcpu=@var{CPU_VERSION}
837 Sets the CPU version being compiled for.
838 @item -merrors-to-file @var{FILENAME}
839 Redirect error output to a file, for broken systems which don't support such
840 behaviour in the shell.
845 The following options are available when @value{AS} is configured for
850 This option sets the largest size of an object that can be referenced
851 implicitly with the @code{gp} register. It is only accepted for targets that
852 use ECOFF format, such as a DECstation running Ultrix. The default value is 8.
854 @cindex MIPS endianness
855 @cindex endianness, MIPS
856 @cindex big endian output, MIPS
858 Generate ``big endian'' format output.
860 @cindex little endian output, MIPS
862 Generate ``little endian'' format output.
871 Generate code for a particular MIPS Instruction Set Architecture level.
872 @samp{-mips1} corresponds to the @sc{r2000} and @sc{r3000} processors,
873 @samp{-mips2} to the @sc{r6000} processor, and @samp{-mips3} to the @sc{r4000}
875 @samp{-mips5}, @samp{-mips32}, and @samp{-mips64} correspond
876 to generic @sc{MIPS V}, @sc{MIPS32}, and @sc{MIPS64} ISA
877 processors, respectively.
881 Generate code for the MIPS @sc{r4650} chip. This tells the assembler to accept
882 the @samp{mad} and @samp{madu} instruction, and to not schedule @samp{nop}
883 instructions around accesses to the @samp{HI} and @samp{LO} registers.
884 @samp{-no-m4650} turns off this option.
888 Generate code for the MIPS-3D Application Specific Extension.
889 This tells the assembler to accept MIPS-3D instructions.
890 @samp{-no-mips3d} turns off this option.
894 Generate code for the MDMX Application Specific Extension.
895 This tells the assembler to accept MDMX instructions.
896 @samp{-no-mdmx} turns off this option.
898 @item -mcpu=@var{CPU}
899 Generate code for a particular MIPS cpu. It is exactly equivalent to
900 @samp{-m@var{cpu}}, except that there are more value of @var{cpu}
904 @item --emulation=@var{name}
905 This option causes @command{@value{AS}} to emulate @command{@value{AS}} configured
906 for some other target, in all respects, including output format (choosing
907 between ELF and ECOFF only), handling of pseudo-opcodes which may generate
908 debugging information or store symbol table information, and default
909 endianness. The available configuration names are: @samp{mipsecoff},
910 @samp{mipself}, @samp{mipslecoff}, @samp{mipsbecoff}, @samp{mipslelf},
911 @samp{mipsbelf}. The first two do not alter the default endianness from that
912 of the primary target for which the assembler was configured; the others change
913 the default to little- or big-endian as indicated by the @samp{b} or @samp{l}
914 in the name. Using @samp{-EB} or @samp{-EL} will override the endianness
915 selection in any case.
917 This option is currently supported only when the primary target
918 @command{@value{AS}} is configured for is a MIPS ELF or ECOFF target.
919 Furthermore, the primary target or others specified with
920 @samp{--enable-targets=@dots{}} at configuration time must include support for
921 the other format, if both are to be available. For example, the Irix 5
922 configuration includes support for both.
924 Eventually, this option will support more configurations, with more
925 fine-grained control over the assembler's behavior, and will be supported for
929 @command{@value{AS}} ignores this option. It is accepted for compatibility with
937 Control how to deal with multiplication overflow and division by zero.
938 @samp{--trap} or @samp{--no-break} (which are synonyms) take a trap exception
939 (and only work for Instruction Set Architecture level 2 and higher);
940 @samp{--break} or @samp{--no-trap} (also synonyms, and the default) take a
944 When this option is used, @command{@value{AS}} will issue a warning every
945 time it generates a nop instruction from a macro.
950 The following options are available when @value{AS} is configured for
956 Enable or disable the JSRI to BSR transformation. By default this is enabled.
957 The command line option @samp{-nojsri2bsr} can be used to disable it.
961 Enable or disable the silicon filter behaviour. By default this is disabled.
962 The default can be overridden by the @samp{-sifilter} command line option.
965 Alter jump instructions for long displacements.
967 @item -mcpu=[210|340]
968 Select the cpu type on the target hardware. This controls which instructions
972 Assemble for a big endian target.
975 Assemble for a little endian target.
981 See the info pages for documentation of the MMIX-specific options.
987 * Manual:: Structure of this Manual
988 * GNU Assembler:: The GNU Assembler
989 * Object Formats:: Object File Formats
990 * Command Line:: Command Line
991 * Input Files:: Input Files
992 * Object:: Output (Object) File
993 * Errors:: Error and Warning Messages
997 @section Structure of this Manual
999 @cindex manual, structure and purpose
1000 This manual is intended to describe what you need to know to use
1001 @sc{gnu} @command{@value{AS}}. We cover the syntax expected in source files, including
1002 notation for symbols, constants, and expressions; the directives that
1003 @command{@value{AS}} understands; and of course how to invoke @command{@value{AS}}.
1006 We also cover special features in the @value{TARGET}
1007 configuration of @command{@value{AS}}, including assembler directives.
1010 This manual also describes some of the machine-dependent features of
1011 various flavors of the assembler.
1014 @cindex machine instructions (not covered)
1015 On the other hand, this manual is @emph{not} intended as an introduction
1016 to programming in assembly language---let alone programming in general!
1017 In a similar vein, we make no attempt to introduce the machine
1018 architecture; we do @emph{not} describe the instruction set, standard
1019 mnemonics, registers or addressing modes that are standard to a
1020 particular architecture.
1022 You may want to consult the manufacturer's
1023 machine architecture manual for this information.
1027 For information on the H8/300 machine instruction set, see @cite{H8/300
1028 Series Programming Manual} (Hitachi ADE--602--025). For the H8/300H,
1029 see @cite{H8/300H Series Programming Manual} (Hitachi).
1032 For information on the H8/500 machine instruction set, see @cite{H8/500
1033 Series Programming Manual} (Hitachi M21T001).
1036 For information on the Hitachi SH machine instruction set, see
1037 @cite{SH-Microcomputer User's Manual} (Hitachi Micro Systems, Inc.).
1040 For information on the Z8000 machine instruction set, see @cite{Z8000 CPU Technical Manual}
1044 @c I think this is premature---doc@cygnus.com, 17jan1991
1046 Throughout this manual, we assume that you are running @dfn{GNU},
1047 the portable operating system from the @dfn{Free Software
1048 Foundation, Inc.}. This restricts our attention to certain kinds of
1049 computer (in particular, the kinds of computers that @sc{gnu} can run on);
1050 once this assumption is granted examples and definitions need less
1053 @command{@value{AS}} is part of a team of programs that turn a high-level
1054 human-readable series of instructions into a low-level
1055 computer-readable series of instructions. Different versions of
1056 @command{@value{AS}} are used for different kinds of computer.
1059 @c There used to be a section "Terminology" here, which defined
1060 @c "contents", "byte", "word", and "long". Defining "word" to any
1061 @c particular size is confusing when the .word directive may generate 16
1062 @c bits on one machine and 32 bits on another; in general, for the user
1063 @c version of this manual, none of these terms seem essential to define.
1064 @c They were used very little even in the former draft of the manual;
1065 @c this draft makes an effort to avoid them (except in names of
1069 @section The GNU Assembler
1071 @c man begin DESCRIPTION
1073 @sc{gnu} @command{as} is really a family of assemblers.
1075 This manual describes @command{@value{AS}}, a member of that family which is
1076 configured for the @value{TARGET} architectures.
1078 If you use (or have used) the @sc{gnu} assembler on one architecture, you
1079 should find a fairly similar environment when you use it on another
1080 architecture. Each version has much in common with the others,
1081 including object file formats, most assembler directives (often called
1082 @dfn{pseudo-ops}) and assembler syntax.@refill
1084 @cindex purpose of @sc{gnu} assembler
1085 @command{@value{AS}} is primarily intended to assemble the output of the
1086 @sc{gnu} C compiler @code{@value{GCC}} for use by the linker
1087 @code{@value{LD}}. Nevertheless, we've tried to make @command{@value{AS}}
1088 assemble correctly everything that other assemblers for the same
1089 machine would assemble.
1091 Any exceptions are documented explicitly (@pxref{Machine Dependencies}).
1094 @c This remark should appear in generic version of manual; assumption
1095 @c here is that generic version sets M680x0.
1096 This doesn't mean @command{@value{AS}} always uses the same syntax as another
1097 assembler for the same architecture; for example, we know of several
1098 incompatible versions of 680x0 assembly language syntax.
1103 Unlike older assemblers, @command{@value{AS}} is designed to assemble a source
1104 program in one pass of the source file. This has a subtle impact on the
1105 @kbd{.org} directive (@pxref{Org,,@code{.org}}).
1107 @node Object Formats
1108 @section Object File Formats
1110 @cindex object file format
1111 The @sc{gnu} assembler can be configured to produce several alternative
1112 object file formats. For the most part, this does not affect how you
1113 write assembly language programs; but directives for debugging symbols
1114 are typically different in different file formats. @xref{Symbol
1115 Attributes,,Symbol Attributes}.
1118 On the @value{TARGET}, @command{@value{AS}} is configured to produce
1119 @value{OBJ-NAME} format object files.
1121 @c The following should exhaust all configs that set MULTI-OBJ, ideally
1123 On the @value{TARGET}, @command{@value{AS}} can be configured to produce either
1124 @code{a.out} or COFF format object files.
1127 On the @value{TARGET}, @command{@value{AS}} can be configured to produce either
1128 @code{b.out} or COFF format object files.
1131 On the @value{TARGET}, @command{@value{AS}} can be configured to produce either
1132 SOM or ELF format object files.
1137 @section Command Line
1139 @cindex command line conventions
1141 After the program name @command{@value{AS}}, the command line may contain
1142 options and file names. Options may appear in any order, and may be
1143 before, after, or between file names. The order of file names is
1146 @cindex standard input, as input file
1148 @file{--} (two hyphens) by itself names the standard input file
1149 explicitly, as one of the files for @command{@value{AS}} to assemble.
1151 @cindex options, command line
1152 Except for @samp{--} any command line argument that begins with a
1153 hyphen (@samp{-}) is an option. Each option changes the behavior of
1154 @command{@value{AS}}. No option changes the way another option works. An
1155 option is a @samp{-} followed by one or more letters; the case of
1156 the letter is important. All options are optional.
1158 Some options expect exactly one file name to follow them. The file
1159 name may either immediately follow the option's letter (compatible
1160 with older assemblers) or it may be the next command argument (@sc{gnu}
1161 standard). These two command lines are equivalent:
1164 @value{AS} -o my-object-file.o mumble.s
1165 @value{AS} -omy-object-file.o mumble.s
1169 @section Input Files
1172 @cindex source program
1173 @cindex files, input
1174 We use the phrase @dfn{source program}, abbreviated @dfn{source}, to
1175 describe the program input to one run of @command{@value{AS}}. The program may
1176 be in one or more files; how the source is partitioned into files
1177 doesn't change the meaning of the source.
1179 @c I added "con" prefix to "catenation" just to prove I can overcome my
1180 @c APL training... doc@cygnus.com
1181 The source program is a concatenation of the text in all the files, in the
1184 @c man begin DESCRIPTION
1185 Each time you run @command{@value{AS}} it assembles exactly one source
1186 program. The source program is made up of one or more files.
1187 (The standard input is also a file.)
1189 You give @command{@value{AS}} a command line that has zero or more input file
1190 names. The input files are read (from left file name to right). A
1191 command line argument (in any position) that has no special meaning
1192 is taken to be an input file name.
1194 If you give @command{@value{AS}} no file names it attempts to read one input file
1195 from the @command{@value{AS}} standard input, which is normally your terminal. You
1196 may have to type @key{ctl-D} to tell @command{@value{AS}} there is no more program
1199 Use @samp{--} if you need to explicitly name the standard input file
1200 in your command line.
1202 If the source is empty, @command{@value{AS}} produces a small, empty object
1207 @subheading Filenames and Line-numbers
1209 @cindex input file linenumbers
1210 @cindex line numbers, in input files
1211 There are two ways of locating a line in the input file (or files) and
1212 either may be used in reporting error messages. One way refers to a line
1213 number in a physical file; the other refers to a line number in a
1214 ``logical'' file. @xref{Errors, ,Error and Warning Messages}.
1216 @dfn{Physical files} are those files named in the command line given
1217 to @command{@value{AS}}.
1219 @dfn{Logical files} are simply names declared explicitly by assembler
1220 directives; they bear no relation to physical files. Logical file names help
1221 error messages reflect the original source file, when @command{@value{AS}} source
1222 is itself synthesized from other files. @command{@value{AS}} understands the
1223 @samp{#} directives emitted by the @code{@value{GCC}} preprocessor. See also
1224 @ref{File,,@code{.file}}.
1227 @section Output (Object) File
1233 Every time you run @command{@value{AS}} it produces an output file, which is
1234 your assembly language program translated into numbers. This file
1235 is the object file. Its default name is
1243 @code{b.out} when @command{@value{AS}} is configured for the Intel 80960.
1245 You can give it another name by using the @option{-o} option. Conventionally,
1246 object file names end with @file{.o}. The default name is used for historical
1247 reasons: older assemblers were capable of assembling self-contained programs
1248 directly into a runnable program. (For some formats, this isn't currently
1249 possible, but it can be done for the @code{a.out} format.)
1253 The object file is meant for input to the linker @code{@value{LD}}. It contains
1254 assembled program code, information to help @code{@value{LD}} integrate
1255 the assembled program into a runnable file, and (optionally) symbolic
1256 information for the debugger.
1258 @c link above to some info file(s) like the description of a.out.
1259 @c don't forget to describe @sc{gnu} info as well as Unix lossage.
1262 @section Error and Warning Messages
1264 @c man begin DESCRIPTION
1266 @cindex error messages
1267 @cindex warning messages
1268 @cindex messages from assembler
1269 @command{@value{AS}} may write warnings and error messages to the standard error
1270 file (usually your terminal). This should not happen when a compiler
1271 runs @command{@value{AS}} automatically. Warnings report an assumption made so
1272 that @command{@value{AS}} could keep assembling a flawed program; errors report a
1273 grave problem that stops the assembly.
1277 @cindex format of warning messages
1278 Warning messages have the format
1281 file_name:@b{NNN}:Warning Message Text
1285 @cindex line numbers, in warnings/errors
1286 (where @b{NNN} is a line number). If a logical file name has been given
1287 (@pxref{File,,@code{.file}}) it is used for the filename, otherwise the name of
1288 the current input file is used. If a logical line number was given
1290 (@pxref{Line,,@code{.line}})
1294 (@pxref{Line,,@code{.line}})
1297 (@pxref{Ln,,@code{.ln}})
1300 then it is used to calculate the number printed,
1301 otherwise the actual line in the current source file is printed. The
1302 message text is intended to be self explanatory (in the grand Unix
1305 @cindex format of error messages
1306 Error messages have the format
1308 file_name:@b{NNN}:FATAL:Error Message Text
1310 The file name and line number are derived as for warning
1311 messages. The actual message text may be rather less explanatory
1312 because many of them aren't supposed to happen.
1315 @chapter Command-Line Options
1317 @cindex options, all versions of assembler
1318 This chapter describes command-line options available in @emph{all}
1319 versions of the @sc{gnu} assembler; @pxref{Machine Dependencies}, for options specific
1321 to the @value{TARGET}.
1324 to particular machine architectures.
1327 @c man begin DESCRIPTION
1329 If you are invoking @command{@value{AS}} via the @sc{gnu} C compiler (version 2),
1330 you can use the @samp{-Wa} option to pass arguments through to the assembler.
1331 The assembler arguments must be separated from each other (and the @samp{-Wa})
1332 by commas. For example:
1335 gcc -c -g -O -Wa,-alh,-L file.c
1339 This passes two options to the assembler: @samp{-alh} (emit a listing to
1340 standard output with with high-level and assembly source) and @samp{-L} (retain
1341 local symbols in the symbol table).
1343 Usually you do not need to use this @samp{-Wa} mechanism, since many compiler
1344 command-line options are automatically passed to the assembler by the compiler.
1345 (You can call the @sc{gnu} compiler driver with the @samp{-v} option to see
1346 precisely what options it passes to each compilation pass, including the
1352 * a:: -a[cdhlns] enable listings
1353 * D:: -D for compatibility
1354 * f:: -f to work faster
1355 * I:: -I for .include search path
1356 @ifclear DIFF-TBL-KLUGE
1357 * K:: -K for compatibility
1359 @ifset DIFF-TBL-KLUGE
1360 * K:: -K for difference tables
1363 * L:: -L to retain local labels
1364 * listing:: --listing-XXX to configure listing output
1365 * M:: -M or --mri to assemble in MRI compatibility mode
1366 * MD:: --MD for dependency tracking
1367 * o:: -o to name the object file
1368 * R:: -R to join data and text sections
1369 * statistics:: --statistics to see statistics about assembly
1370 * traditional-format:: --traditional-format for compatible output
1371 * v:: -v to announce version
1372 * W:: -W, --no-warn, --warn, --fatal-warnings to control warnings
1373 * Z:: -Z to make object file even after errors
1377 @section Enable Listings: @option{-a[cdhlns]}
1386 @cindex listings, enabling
1387 @cindex assembly listings, enabling
1389 These options enable listing output from the assembler. By itself,
1390 @samp{-a} requests high-level, assembly, and symbols listing.
1391 You can use other letters to select specific options for the list:
1392 @samp{-ah} requests a high-level language listing,
1393 @samp{-al} requests an output-program assembly listing, and
1394 @samp{-as} requests a symbol table listing.
1395 High-level listings require that a compiler debugging option like
1396 @samp{-g} be used, and that assembly listings (@samp{-al}) be requested
1399 Use the @samp{-ac} option to omit false conditionals from a listing. Any lines
1400 which are not assembled because of a false @code{.if} (or @code{.ifdef}, or any
1401 other conditional), or a true @code{.if} followed by an @code{.else}, will be
1402 omitted from the listing.
1404 Use the @samp{-ad} option to omit debugging directives from the
1407 Once you have specified one of these options, you can further control
1408 listing output and its appearance using the directives @code{.list},
1409 @code{.nolist}, @code{.psize}, @code{.eject}, @code{.title}, and
1411 The @samp{-an} option turns off all forms processing.
1412 If you do not request listing output with one of the @samp{-a} options, the
1413 listing-control directives have no effect.
1415 The letters after @samp{-a} may be combined into one option,
1416 @emph{e.g.}, @samp{-aln}.
1418 Note if the assembler source is coming from the standard input (eg because it
1419 is being created by @code{@value{GCC}} and the @samp{-pipe} command line switch
1420 is being used) then the listing will not contain any comments or preprocessor
1421 directives. This is because the listing code buffers input source lines from
1422 stdin only after they have been preprocessed by the assembler. This reduces
1423 memory usage and makes the code more efficient.
1426 @section @option{-D}
1429 This option has no effect whatsoever, but it is accepted to make it more
1430 likely that scripts written for other assemblers also work with
1431 @command{@value{AS}}.
1434 @section Work Faster: @option{-f}
1437 @cindex trusted compiler
1438 @cindex faster processing (@option{-f})
1439 @samp{-f} should only be used when assembling programs written by a
1440 (trusted) compiler. @samp{-f} stops the assembler from doing whitespace
1441 and comment preprocessing on
1442 the input file(s) before assembling them. @xref{Preprocessing,
1446 @emph{Warning:} if you use @samp{-f} when the files actually need to be
1447 preprocessed (if they contain comments, for example), @command{@value{AS}} does
1452 @section @code{.include} search path: @option{-I} @var{path}
1454 @kindex -I @var{path}
1455 @cindex paths for @code{.include}
1456 @cindex search path for @code{.include}
1457 @cindex @code{include} directive search path
1458 Use this option to add a @var{path} to the list of directories
1459 @command{@value{AS}} searches for files specified in @code{.include}
1460 directives (@pxref{Include,,@code{.include}}). You may use @option{-I} as
1461 many times as necessary to include a variety of paths. The current
1462 working directory is always searched first; after that, @command{@value{AS}}
1463 searches any @samp{-I} directories in the same order as they were
1464 specified (left to right) on the command line.
1467 @section Difference Tables: @option{-K}
1470 @ifclear DIFF-TBL-KLUGE
1471 On the @value{TARGET} family, this option is allowed, but has no effect. It is
1472 permitted for compatibility with the @sc{gnu} assembler on other platforms,
1473 where it can be used to warn when the assembler alters the machine code
1474 generated for @samp{.word} directives in difference tables. The @value{TARGET}
1475 family does not have the addressing limitations that sometimes lead to this
1476 alteration on other platforms.
1479 @ifset DIFF-TBL-KLUGE
1480 @cindex difference tables, warning
1481 @cindex warning for altered difference tables
1482 @command{@value{AS}} sometimes alters the code emitted for directives of the form
1483 @samp{.word @var{sym1}-@var{sym2}}; @pxref{Word,,@code{.word}}.
1484 You can use the @samp{-K} option if you want a warning issued when this
1489 @section Include Local Labels: @option{-L}
1492 @cindex local labels, retaining in output
1493 Labels beginning with @samp{L} (upper case only) are called @dfn{local
1494 labels}. @xref{Symbol Names}. Normally you do not see such labels when
1495 debugging, because they are intended for the use of programs (like
1496 compilers) that compose assembler programs, not for your notice.
1497 Normally both @command{@value{AS}} and @code{@value{LD}} discard such labels, so you do not
1498 normally debug with them.
1500 This option tells @command{@value{AS}} to retain those @samp{L@dots{}} symbols
1501 in the object file. Usually if you do this you also tell the linker
1502 @code{@value{LD}} to preserve symbols whose names begin with @samp{L}.
1504 By default, a local label is any label beginning with @samp{L}, but each
1505 target is allowed to redefine the local label prefix.
1507 On the HPPA local labels begin with @samp{L$}.
1511 @section Configuring listing output: @option{--listing}
1513 The listing feature of the assembler can be enabled via the command line switch
1514 @samp{-a} (@pxref{a}). This feature combines the input source file(s) with a
1515 hex dump of the corresponding locations in the output object file, and displays
1516 them as a listing file. The format of this listing can be controlled by pseudo
1517 ops inside the assembler source (@pxref{List} @pxref{Title} @pxref{Sbttl}
1518 @pxref{Psize} @pxref{Eject}) and also by the following switches:
1521 @item --listing-lhs-width=@samp{number}
1522 @kindex --listing-lhs-width
1523 @cindex Width of first line disassembly output
1524 Sets the maximum width, in words, of the first line of the hex byte dump. This
1525 dump appears on the left hand side of the listing output.
1527 @item --listing-lhs-width2=@samp{number}
1528 @kindex --listing-lhs-width2
1529 @cindex Width of continuation lines of disassembly output
1530 Sets the maximum width, in words, of any further lines of the hex byte dump for
1531 a given inut source line. If this value is not specified, it defaults to being
1532 the same as the value specified for @samp{--listing-lhs-width}. If neither
1533 switch is used the default is to one.
1535 @item --listing-rhs-width=@samp{number}
1536 @kindex --listing-rhs-width
1537 @cindex Width of source line output
1538 Sets the maximum width, in characters, of the source line that is displayed
1539 alongside the hex dump. The default value for this parameter is 100. The
1540 source line is displayed on the right hand side of the listing output.
1542 @item --listing-cont-lines=@samp{number}
1543 @kindex --listing-cont-lines
1544 @cindex Maximum number of continuation lines
1545 Sets the maximum number of continuation lines of hex dump that will be
1546 displayed for a given single line of source input. The default value is 4.
1550 @section Assemble in MRI Compatibility Mode: @option{-M}
1553 @cindex MRI compatibility mode
1554 The @option{-M} or @option{--mri} option selects MRI compatibility mode. This
1555 changes the syntax and pseudo-op handling of @command{@value{AS}} to make it
1556 compatible with the @code{ASM68K} or the @code{ASM960} (depending upon the
1557 configured target) assembler from Microtec Research. The exact nature of the
1558 MRI syntax will not be documented here; see the MRI manuals for more
1559 information. Note in particular that the handling of macros and macro
1560 arguments is somewhat different. The purpose of this option is to permit
1561 assembling existing MRI assembler code using @command{@value{AS}}.
1563 The MRI compatibility is not complete. Certain operations of the MRI assembler
1564 depend upon its object file format, and can not be supported using other object
1565 file formats. Supporting these would require enhancing each object file format
1566 individually. These are:
1569 @item global symbols in common section
1571 The m68k MRI assembler supports common sections which are merged by the linker.
1572 Other object file formats do not support this. @command{@value{AS}} handles
1573 common sections by treating them as a single common symbol. It permits local
1574 symbols to be defined within a common section, but it can not support global
1575 symbols, since it has no way to describe them.
1577 @item complex relocations
1579 The MRI assemblers support relocations against a negated section address, and
1580 relocations which combine the start addresses of two or more sections. These
1581 are not support by other object file formats.
1583 @item @code{END} pseudo-op specifying start address
1585 The MRI @code{END} pseudo-op permits the specification of a start address.
1586 This is not supported by other object file formats. The start address may
1587 instead be specified using the @option{-e} option to the linker, or in a linker
1590 @item @code{IDNT}, @code{.ident} and @code{NAME} pseudo-ops
1592 The MRI @code{IDNT}, @code{.ident} and @code{NAME} pseudo-ops assign a module
1593 name to the output file. This is not supported by other object file formats.
1595 @item @code{ORG} pseudo-op
1597 The m68k MRI @code{ORG} pseudo-op begins an absolute section at a given
1598 address. This differs from the usual @command{@value{AS}} @code{.org} pseudo-op,
1599 which changes the location within the current section. Absolute sections are
1600 not supported by other object file formats. The address of a section may be
1601 assigned within a linker script.
1604 There are some other features of the MRI assembler which are not supported by
1605 @command{@value{AS}}, typically either because they are difficult or because they
1606 seem of little consequence. Some of these may be supported in future releases.
1610 @item EBCDIC strings
1612 EBCDIC strings are not supported.
1614 @item packed binary coded decimal
1616 Packed binary coded decimal is not supported. This means that the @code{DC.P}
1617 and @code{DCB.P} pseudo-ops are not supported.
1619 @item @code{FEQU} pseudo-op
1621 The m68k @code{FEQU} pseudo-op is not supported.
1623 @item @code{NOOBJ} pseudo-op
1625 The m68k @code{NOOBJ} pseudo-op is not supported.
1627 @item @code{OPT} branch control options
1629 The m68k @code{OPT} branch control options---@code{B}, @code{BRS}, @code{BRB},
1630 @code{BRL}, and @code{BRW}---are ignored. @command{@value{AS}} automatically
1631 relaxes all branches, whether forward or backward, to an appropriate size, so
1632 these options serve no purpose.
1634 @item @code{OPT} list control options
1636 The following m68k @code{OPT} list control options are ignored: @code{C},
1637 @code{CEX}, @code{CL}, @code{CRE}, @code{E}, @code{G}, @code{I}, @code{M},
1638 @code{MEX}, @code{MC}, @code{MD}, @code{X}.
1640 @item other @code{OPT} options
1642 The following m68k @code{OPT} options are ignored: @code{NEST}, @code{O},
1643 @code{OLD}, @code{OP}, @code{P}, @code{PCO}, @code{PCR}, @code{PCS}, @code{R}.
1645 @item @code{OPT} @code{D} option is default
1647 The m68k @code{OPT} @code{D} option is the default, unlike the MRI assembler.
1648 @code{OPT NOD} may be used to turn it off.
1650 @item @code{XREF} pseudo-op.
1652 The m68k @code{XREF} pseudo-op is ignored.
1654 @item @code{.debug} pseudo-op
1656 The i960 @code{.debug} pseudo-op is not supported.
1658 @item @code{.extended} pseudo-op
1660 The i960 @code{.extended} pseudo-op is not supported.
1662 @item @code{.list} pseudo-op.
1664 The various options of the i960 @code{.list} pseudo-op are not supported.
1666 @item @code{.optimize} pseudo-op
1668 The i960 @code{.optimize} pseudo-op is not supported.
1670 @item @code{.output} pseudo-op
1672 The i960 @code{.output} pseudo-op is not supported.
1674 @item @code{.setreal} pseudo-op
1676 The i960 @code{.setreal} pseudo-op is not supported.
1681 @section Dependency tracking: @option{--MD}
1684 @cindex dependency tracking
1687 @command{@value{AS}} can generate a dependency file for the file it creates. This
1688 file consists of a single rule suitable for @code{make} describing the
1689 dependencies of the main source file.
1691 The rule is written to the file named in its argument.
1693 This feature is used in the automatic updating of makefiles.
1696 @section Name the Object File: @option{-o}
1699 @cindex naming object file
1700 @cindex object file name
1701 There is always one object file output when you run @command{@value{AS}}. By
1702 default it has the name
1705 @file{a.out} (or @file{b.out}, for Intel 960 targets only).
1719 You use this option (which takes exactly one filename) to give the
1720 object file a different name.
1722 Whatever the object file is called, @command{@value{AS}} overwrites any
1723 existing file of the same name.
1726 @section Join Data and Text Sections: @option{-R}
1729 @cindex data and text sections, joining
1730 @cindex text and data sections, joining
1731 @cindex joining text and data sections
1732 @cindex merging text and data sections
1733 @option{-R} tells @command{@value{AS}} to write the object file as if all
1734 data-section data lives in the text section. This is only done at
1735 the very last moment: your binary data are the same, but data
1736 section parts are relocated differently. The data section part of
1737 your object file is zero bytes long because all its bytes are
1738 appended to the text section. (@xref{Sections,,Sections and Relocation}.)
1740 When you specify @option{-R} it would be possible to generate shorter
1741 address displacements (because we do not have to cross between text and
1742 data section). We refrain from doing this simply for compatibility with
1743 older versions of @command{@value{AS}}. In future, @option{-R} may work this way.
1746 When @command{@value{AS}} is configured for COFF output,
1747 this option is only useful if you use sections named @samp{.text} and
1752 @option{-R} is not supported for any of the HPPA targets. Using
1753 @option{-R} generates a warning from @command{@value{AS}}.
1757 @section Display Assembly Statistics: @option{--statistics}
1759 @kindex --statistics
1760 @cindex statistics, about assembly
1761 @cindex time, total for assembly
1762 @cindex space used, maximum for assembly
1763 Use @samp{--statistics} to display two statistics about the resources used by
1764 @command{@value{AS}}: the maximum amount of space allocated during the assembly
1765 (in bytes), and the total execution time taken for the assembly (in @sc{cpu}
1768 @node traditional-format
1769 @section Compatible output: @option{--traditional-format}
1771 @kindex --traditional-format
1772 For some targets, the output of @command{@value{AS}} is different in some ways
1773 from the output of some existing assembler. This switch requests
1774 @command{@value{AS}} to use the traditional format instead.
1776 For example, it disables the exception frame optimizations which
1777 @command{@value{AS}} normally does by default on @code{@value{GCC}} output.
1780 @section Announce Version: @option{-v}
1784 @cindex assembler version
1785 @cindex version of assembler
1786 You can find out what version of as is running by including the
1787 option @samp{-v} (which you can also spell as @samp{-version}) on the
1791 @section Control Warnings: @option{-W}, @option{--warn}, @option{--no-warn}, @option{--fatal-warnings}
1793 @command{@value{AS}} should never give a warning or error message when
1794 assembling compiler output. But programs written by people often
1795 cause @command{@value{AS}} to give a warning that a particular assumption was
1796 made. All such warnings are directed to the standard error file.
1799 @kindex @samp{--no-warn}
1800 @cindex suppressing warnings
1801 @cindex warnings, suppressing
1802 If you use the @option{-W} and @option{--no-warn} options, no warnings are issued.
1803 This only affects the warning messages: it does not change any particular of
1804 how @command{@value{AS}} assembles your file. Errors, which stop the assembly,
1807 @kindex @samp{--fatal-warnings}
1808 @cindex errors, caused by warnings
1809 @cindex warnings, causing error
1810 If you use the @option{--fatal-warnings} option, @command{@value{AS}} considers
1811 files that generate warnings to be in error.
1813 @kindex @samp{--warn}
1814 @cindex warnings, switching on
1815 You can switch these options off again by specifying @option{--warn}, which
1816 causes warnings to be output as usual.
1819 @section Generate Object File in Spite of Errors: @option{-Z}
1820 @cindex object file, after errors
1821 @cindex errors, continuing after
1822 After an error message, @command{@value{AS}} normally produces no output. If for
1823 some reason you are interested in object file output even after
1824 @command{@value{AS}} gives an error message on your program, use the @samp{-Z}
1825 option. If there are any errors, @command{@value{AS}} continues anyways, and
1826 writes an object file after a final warning message of the form @samp{@var{n}
1827 errors, @var{m} warnings, generating bad object file.}
1832 @cindex machine-independent syntax
1833 @cindex syntax, machine-independent
1834 This chapter describes the machine-independent syntax allowed in a
1835 source file. @command{@value{AS}} syntax is similar to what many other
1836 assemblers use; it is inspired by the BSD 4.2
1841 assembler, except that @command{@value{AS}} does not assemble Vax bit-fields.
1845 * Preprocessing:: Preprocessing
1846 * Whitespace:: Whitespace
1847 * Comments:: Comments
1848 * Symbol Intro:: Symbols
1849 * Statements:: Statements
1850 * Constants:: Constants
1854 @section Preprocessing
1856 @cindex preprocessing
1857 The @command{@value{AS}} internal preprocessor:
1859 @cindex whitespace, removed by preprocessor
1861 adjusts and removes extra whitespace. It leaves one space or tab before
1862 the keywords on a line, and turns any other whitespace on the line into
1865 @cindex comments, removed by preprocessor
1867 removes all comments, replacing them with a single space, or an
1868 appropriate number of newlines.
1870 @cindex constants, converted by preprocessor
1872 converts character constants into the appropriate numeric values.
1875 It does not do macro processing, include file handling, or
1876 anything else you may get from your C compiler's preprocessor. You can
1877 do include file processing with the @code{.include} directive
1878 (@pxref{Include,,@code{.include}}). You can use the @sc{gnu} C compiler driver
1879 to get other ``CPP'' style preprocessing, by giving the input file a
1880 @samp{.S} suffix. @xref{Overall Options,, Options Controlling the Kind of
1881 Output, gcc.info, Using GNU CC}.
1883 Excess whitespace, comments, and character constants
1884 cannot be used in the portions of the input text that are not
1887 @cindex turning preprocessing on and off
1888 @cindex preprocessing, turning on and off
1891 If the first line of an input file is @code{#NO_APP} or if you use the
1892 @samp{-f} option, whitespace and comments are not removed from the input file.
1893 Within an input file, you can ask for whitespace and comment removal in
1894 specific portions of the by putting a line that says @code{#APP} before the
1895 text that may contain whitespace or comments, and putting a line that says
1896 @code{#NO_APP} after this text. This feature is mainly intend to support
1897 @code{asm} statements in compilers whose output is otherwise free of comments
1904 @dfn{Whitespace} is one or more blanks or tabs, in any order.
1905 Whitespace is used to separate symbols, and to make programs neater for
1906 people to read. Unless within character constants
1907 (@pxref{Characters,,Character Constants}), any whitespace means the same
1908 as exactly one space.
1914 There are two ways of rendering comments to @command{@value{AS}}. In both
1915 cases the comment is equivalent to one space.
1917 Anything from @samp{/*} through the next @samp{*/} is a comment.
1918 This means you may not nest these comments.
1922 The only way to include a newline ('\n') in a comment
1923 is to use this sort of comment.
1926 /* This sort of comment does not nest. */
1929 @cindex line comment character
1930 Anything from the @dfn{line comment} character to the next newline
1931 is considered a comment and is ignored. The line comment character is
1933 @samp{;} for the AMD 29K family;
1936 @samp{;} on the ARC;
1939 @samp{@@} on the ARM;
1942 @samp{;} for the H8/300 family;
1945 @samp{!} for the H8/500 family;
1948 @samp{;} for the HPPA;
1951 @samp{#} on the i386 and x86-64;
1954 @samp{#} on the i960;
1957 @samp{;} for the PDP-11;
1960 @samp{;} for picoJava;
1963 @samp{;} for Motorola PowerPC;
1966 @samp{!} for the Hitachi SH;
1969 @samp{!} on the SPARC;
1972 @samp{#} on the m32r;
1975 @samp{|} on the 680x0;
1978 @samp{#} on the 68HC11 and 68HC12;
1981 @samp{;} on the M880x0;
1984 @samp{#} on the Vax;
1987 @samp{!} for the Z8000;
1990 @samp{#} on the V850;
1992 see @ref{Machine Dependencies}. @refill
1993 @c FIXME What about i860?
1996 On some machines there are two different line comment characters. One
1997 character only begins a comment if it is the first non-whitespace character on
1998 a line, while the other always begins a comment.
2002 The V850 assembler also supports a double dash as starting a comment that
2003 extends to the end of the line.
2009 @cindex lines starting with @code{#}
2010 @cindex logical line numbers
2011 To be compatible with past assemblers, lines that begin with @samp{#} have a
2012 special interpretation. Following the @samp{#} should be an absolute
2013 expression (@pxref{Expressions}): the logical line number of the @emph{next}
2014 line. Then a string (@pxref{Strings,, Strings}) is allowed: if present it is a
2015 new logical file name. The rest of the line, if any, should be whitespace.
2017 If the first non-whitespace characters on the line are not numeric,
2018 the line is ignored. (Just like a comment.)
2021 # This is an ordinary comment.
2022 # 42-6 "new_file_name" # New logical file name
2023 # This is logical line # 36.
2025 This feature is deprecated, and may disappear from future versions
2026 of @command{@value{AS}}.
2031 @cindex characters used in symbols
2032 @ifclear SPECIAL-SYMS
2033 A @dfn{symbol} is one or more characters chosen from the set of all
2034 letters (both upper and lower case), digits and the three characters
2040 A @dfn{symbol} is one or more characters chosen from the set of all
2041 letters (both upper and lower case), digits and the three characters
2042 @samp{._$}. (Save that, on the H8/300 only, you may not use @samp{$} in
2048 On most machines, you can also use @code{$} in symbol names; exceptions
2049 are noted in @ref{Machine Dependencies}.
2051 No symbol may begin with a digit. Case is significant.
2052 There is no length limit: all characters are significant. Symbols are
2053 delimited by characters not in that set, or by the beginning of a file
2054 (since the source program must end with a newline, the end of a file is
2055 not a possible symbol delimiter). @xref{Symbols}.
2056 @cindex length of symbols
2061 @cindex statements, structure of
2062 @cindex line separator character
2063 @cindex statement separator character
2065 @ifclear abnormal-separator
2066 A @dfn{statement} ends at a newline character (@samp{\n}) or at a
2067 semicolon (@samp{;}). The newline or semicolon is considered part of
2068 the preceding statement. Newlines and semicolons within character
2069 constants are an exception: they do not end statements.
2071 @ifset abnormal-separator
2073 A @dfn{statement} ends at a newline character (@samp{\n}) or an ``at''
2074 sign (@samp{@@}). The newline or at sign is considered part of the
2075 preceding statement. Newlines and at signs within character constants
2076 are an exception: they do not end statements.
2079 A @dfn{statement} ends at a newline character (@samp{\n}) or an exclamation
2080 point (@samp{!}). The newline or exclamation point is considered part of the
2081 preceding statement. Newlines and exclamation points within character
2082 constants are an exception: they do not end statements.
2085 A @dfn{statement} ends at a newline character (@samp{\n}); or (for the
2086 H8/300) a dollar sign (@samp{$}); or (for the
2089 (@samp{;}). The newline or separator character is considered part of
2090 the preceding statement. Newlines and separators within character
2091 constants are an exception: they do not end statements.
2096 A @dfn{statement} ends at a newline character (@samp{\n}) or line
2097 separator character. (The line separator is usually @samp{;}, unless
2098 this conflicts with the comment character; @pxref{Machine Dependencies}.) The
2099 newline or separator character is considered part of the preceding
2100 statement. Newlines and separators within character constants are an
2101 exception: they do not end statements.
2104 @cindex newline, required at file end
2105 @cindex EOF, newline must precede
2106 It is an error to end any statement with end-of-file: the last
2107 character of any input file should be a newline.@refill
2109 An empty statement is allowed, and may include whitespace. It is ignored.
2111 @cindex instructions and directives
2112 @cindex directives and instructions
2113 @c "key symbol" is not used elsewhere in the document; seems pedantic to
2114 @c @defn{} it in that case, as was done previously... doc@cygnus.com,
2116 A statement begins with zero or more labels, optionally followed by a
2117 key symbol which determines what kind of statement it is. The key
2118 symbol determines the syntax of the rest of the statement. If the
2119 symbol begins with a dot @samp{.} then the statement is an assembler
2120 directive: typically valid for any computer. If the symbol begins with
2121 a letter the statement is an assembly language @dfn{instruction}: it
2122 assembles into a machine language instruction.
2124 Different versions of @command{@value{AS}} for different computers
2125 recognize different instructions. In fact, the same symbol may
2126 represent a different instruction in a different computer's assembly
2130 @cindex @code{:} (label)
2131 @cindex label (@code{:})
2132 A label is a symbol immediately followed by a colon (@code{:}).
2133 Whitespace before a label or after a colon is permitted, but you may not
2134 have whitespace between a label's symbol and its colon. @xref{Labels}.
2137 For HPPA targets, labels need not be immediately followed by a colon, but
2138 the definition of a label must begin in column zero. This also implies that
2139 only one label may be defined on each line.
2143 label: .directive followed by something
2144 another_label: # This is an empty statement.
2145 instruction operand_1, operand_2, @dots{}
2152 A constant is a number, written so that its value is known by
2153 inspection, without knowing any context. Like this:
2156 .byte 74, 0112, 092, 0x4A, 0X4a, 'J, '\J # All the same value.
2157 .ascii "Ring the bell\7" # A string constant.
2158 .octa 0x123456789abcdef0123456789ABCDEF0 # A bignum.
2159 .float 0f-314159265358979323846264338327\
2160 95028841971.693993751E-40 # - pi, a flonum.
2165 * Characters:: Character Constants
2166 * Numbers:: Number Constants
2170 @subsection Character Constants
2172 @cindex character constants
2173 @cindex constants, character
2174 There are two kinds of character constants. A @dfn{character} stands
2175 for one character in one byte and its value may be used in
2176 numeric expressions. String constants (properly called string
2177 @emph{literals}) are potentially many bytes and their values may not be
2178 used in arithmetic expressions.
2182 * Chars:: Characters
2186 @subsubsection Strings
2188 @cindex string constants
2189 @cindex constants, string
2190 A @dfn{string} is written between double-quotes. It may contain
2191 double-quotes or null characters. The way to get special characters
2192 into a string is to @dfn{escape} these characters: precede them with
2193 a backslash @samp{\} character. For example @samp{\\} represents
2194 one backslash: the first @code{\} is an escape which tells
2195 @command{@value{AS}} to interpret the second character literally as a backslash
2196 (which prevents @command{@value{AS}} from recognizing the second @code{\} as an
2197 escape character). The complete list of escapes follows.
2199 @cindex escape codes, character
2200 @cindex character escape codes
2203 @c Mnemonic for ACKnowledge; for ASCII this is octal code 007.
2205 @cindex @code{\b} (backspace character)
2206 @cindex backspace (@code{\b})
2208 Mnemonic for backspace; for ASCII this is octal code 010.
2211 @c Mnemonic for EOText; for ASCII this is octal code 004.
2213 @cindex @code{\f} (formfeed character)
2214 @cindex formfeed (@code{\f})
2216 Mnemonic for FormFeed; for ASCII this is octal code 014.
2218 @cindex @code{\n} (newline character)
2219 @cindex newline (@code{\n})
2221 Mnemonic for newline; for ASCII this is octal code 012.
2224 @c Mnemonic for prefix; for ASCII this is octal code 033, usually known as @code{escape}.
2226 @cindex @code{\r} (carriage return character)
2227 @cindex carriage return (@code{\r})
2229 Mnemonic for carriage-Return; for ASCII this is octal code 015.
2232 @c Mnemonic for space; for ASCII this is octal code 040. Included for compliance with
2233 @c other assemblers.
2235 @cindex @code{\t} (tab)
2236 @cindex tab (@code{\t})
2238 Mnemonic for horizontal Tab; for ASCII this is octal code 011.
2241 @c Mnemonic for Vertical tab; for ASCII this is octal code 013.
2242 @c @item \x @var{digit} @var{digit} @var{digit}
2243 @c A hexadecimal character code. The numeric code is 3 hexadecimal digits.
2245 @cindex @code{\@var{ddd}} (octal character code)
2246 @cindex octal character code (@code{\@var{ddd}})
2247 @item \ @var{digit} @var{digit} @var{digit}
2248 An octal character code. The numeric code is 3 octal digits.
2249 For compatibility with other Unix systems, 8 and 9 are accepted as digits:
2250 for example, @code{\008} has the value 010, and @code{\009} the value 011.
2252 @cindex @code{\@var{xd...}} (hex character code)
2253 @cindex hex character code (@code{\@var{xd...}})
2254 @item \@code{x} @var{hex-digits...}
2255 A hex character code. All trailing hex digits are combined. Either upper or
2256 lower case @code{x} works.
2258 @cindex @code{\\} (@samp{\} character)
2259 @cindex backslash (@code{\\})
2261 Represents one @samp{\} character.
2264 @c Represents one @samp{'} (accent acute) character.
2265 @c This is needed in single character literals
2266 @c (@xref{Characters,,Character Constants}.) to represent
2269 @cindex @code{\"} (doublequote character)
2270 @cindex doublequote (@code{\"})
2272 Represents one @samp{"} character. Needed in strings to represent
2273 this character, because an unescaped @samp{"} would end the string.
2275 @item \ @var{anything-else}
2276 Any other character when escaped by @kbd{\} gives a warning, but
2277 assembles as if the @samp{\} was not present. The idea is that if
2278 you used an escape sequence you clearly didn't want the literal
2279 interpretation of the following character. However @command{@value{AS}} has no
2280 other interpretation, so @command{@value{AS}} knows it is giving you the wrong
2281 code and warns you of the fact.
2284 Which characters are escapable, and what those escapes represent,
2285 varies widely among assemblers. The current set is what we think
2286 the BSD 4.2 assembler recognizes, and is a subset of what most C
2287 compilers recognize. If you are in doubt, do not use an escape
2291 @subsubsection Characters
2293 @cindex single character constant
2294 @cindex character, single
2295 @cindex constant, single character
2296 A single character may be written as a single quote immediately
2297 followed by that character. The same escapes apply to characters as
2298 to strings. So if you want to write the character backslash, you
2299 must write @kbd{'\\} where the first @code{\} escapes the second
2300 @code{\}. As you can see, the quote is an acute accent, not a
2301 grave accent. A newline
2303 @ifclear abnormal-separator
2304 (or semicolon @samp{;})
2306 @ifset abnormal-separator
2308 (or at sign @samp{@@})
2311 (or dollar sign @samp{$}, for the H8/300; or semicolon @samp{;} for the
2317 immediately following an acute accent is taken as a literal character
2318 and does not count as the end of a statement. The value of a character
2319 constant in a numeric expression is the machine's byte-wide code for
2320 that character. @command{@value{AS}} assumes your character code is ASCII:
2321 @kbd{'A} means 65, @kbd{'B} means 66, and so on. @refill
2324 @subsection Number Constants
2326 @cindex constants, number
2327 @cindex number constants
2328 @command{@value{AS}} distinguishes three kinds of numbers according to how they
2329 are stored in the target machine. @emph{Integers} are numbers that
2330 would fit into an @code{int} in the C language. @emph{Bignums} are
2331 integers, but they are stored in more than 32 bits. @emph{Flonums}
2332 are floating point numbers, described below.
2335 * Integers:: Integers
2340 * Bit Fields:: Bit Fields
2346 @subsubsection Integers
2348 @cindex constants, integer
2350 @cindex binary integers
2351 @cindex integers, binary
2352 A binary integer is @samp{0b} or @samp{0B} followed by zero or more of
2353 the binary digits @samp{01}.
2355 @cindex octal integers
2356 @cindex integers, octal
2357 An octal integer is @samp{0} followed by zero or more of the octal
2358 digits (@samp{01234567}).
2360 @cindex decimal integers
2361 @cindex integers, decimal
2362 A decimal integer starts with a non-zero digit followed by zero or
2363 more digits (@samp{0123456789}).
2365 @cindex hexadecimal integers
2366 @cindex integers, hexadecimal
2367 A hexadecimal integer is @samp{0x} or @samp{0X} followed by one or
2368 more hexadecimal digits chosen from @samp{0123456789abcdefABCDEF}.
2370 Integers have the usual values. To denote a negative integer, use
2371 the prefix operator @samp{-} discussed under expressions
2372 (@pxref{Prefix Ops,,Prefix Operators}).
2375 @subsubsection Bignums
2378 @cindex constants, bignum
2379 A @dfn{bignum} has the same syntax and semantics as an integer
2380 except that the number (or its negative) takes more than 32 bits to
2381 represent in binary. The distinction is made because in some places
2382 integers are permitted while bignums are not.
2385 @subsubsection Flonums
2387 @cindex floating point numbers
2388 @cindex constants, floating point
2390 @cindex precision, floating point
2391 A @dfn{flonum} represents a floating point number. The translation is
2392 indirect: a decimal floating point number from the text is converted by
2393 @command{@value{AS}} to a generic binary floating point number of more than
2394 sufficient precision. This generic floating point number is converted
2395 to a particular computer's floating point format (or formats) by a
2396 portion of @command{@value{AS}} specialized to that computer.
2398 A flonum is written by writing (in order)
2403 (@samp{0} is optional on the HPPA.)
2407 A letter, to tell @command{@value{AS}} the rest of the number is a flonum.
2409 @kbd{e} is recommended. Case is not important.
2411 @c FIXME: verify if flonum syntax really this vague for most cases
2412 (Any otherwise illegal letter works here, but that might be changed. Vax BSD
2413 4.2 assembler seems to allow any of @samp{defghDEFGH}.)
2416 On the H8/300, H8/500,
2418 and AMD 29K architectures, the letter must be
2419 one of the letters @samp{DFPRSX} (in upper or lower case).
2421 On the ARC, the letter must be one of the letters @samp{DFRS}
2422 (in upper or lower case).
2424 On the Intel 960 architecture, the letter must be
2425 one of the letters @samp{DFT} (in upper or lower case).
2427 On the HPPA architecture, the letter must be @samp{E} (upper case only).
2431 One of the letters @samp{DFPRSX} (in upper or lower case).
2434 One of the letters @samp{DFRS} (in upper or lower case).
2437 One of the letters @samp{DFPRSX} (in upper or lower case).
2440 The letter @samp{E} (upper case only).
2443 One of the letters @samp{DFT} (in upper or lower case).
2448 An optional sign: either @samp{+} or @samp{-}.
2451 An optional @dfn{integer part}: zero or more decimal digits.
2454 An optional @dfn{fractional part}: @samp{.} followed by zero
2455 or more decimal digits.
2458 An optional exponent, consisting of:
2462 An @samp{E} or @samp{e}.
2463 @c I can't find a config where "EXP_CHARS" is other than 'eE', but in
2464 @c principle this can perfectly well be different on different targets.
2466 Optional sign: either @samp{+} or @samp{-}.
2468 One or more decimal digits.
2473 At least one of the integer part or the fractional part must be
2474 present. The floating point number has the usual base-10 value.
2476 @command{@value{AS}} does all processing using integers. Flonums are computed
2477 independently of any floating point hardware in the computer running
2478 @command{@value{AS}}.
2482 @c Bit fields are written as a general facility but are also controlled
2483 @c by a conditional-compilation flag---which is as of now (21mar91)
2484 @c turned on only by the i960 config of GAS.
2486 @subsubsection Bit Fields
2489 @cindex constants, bit field
2490 You can also define numeric constants as @dfn{bit fields}.
2491 specify two numbers separated by a colon---
2493 @var{mask}:@var{value}
2496 @command{@value{AS}} applies a bitwise @sc{and} between @var{mask} and
2499 The resulting number is then packed
2501 @c this conditional paren in case bit fields turned on elsewhere than 960
2502 (in host-dependent byte order)
2504 into a field whose width depends on which assembler directive has the
2505 bit-field as its argument. Overflow (a result from the bitwise and
2506 requiring more binary digits to represent) is not an error; instead,
2507 more constants are generated, of the specified width, beginning with the
2508 least significant digits.@refill
2510 The directives @code{.byte}, @code{.hword}, @code{.int}, @code{.long},
2511 @code{.short}, and @code{.word} accept bit-field arguments.
2516 @chapter Sections and Relocation
2521 * Secs Background:: Background
2522 * Ld Sections:: Linker Sections
2523 * As Sections:: Assembler Internal Sections
2524 * Sub-Sections:: Sub-Sections
2528 @node Secs Background
2531 Roughly, a section is a range of addresses, with no gaps; all data
2532 ``in'' those addresses is treated the same for some particular purpose.
2533 For example there may be a ``read only'' section.
2535 @cindex linker, and assembler
2536 @cindex assembler, and linker
2537 The linker @code{@value{LD}} reads many object files (partial programs) and
2538 combines their contents to form a runnable program. When @command{@value{AS}}
2539 emits an object file, the partial program is assumed to start at address 0.
2540 @code{@value{LD}} assigns the final addresses for the partial program, so that
2541 different partial programs do not overlap. This is actually an
2542 oversimplification, but it suffices to explain how @command{@value{AS}} uses
2545 @code{@value{LD}} moves blocks of bytes of your program to their run-time
2546 addresses. These blocks slide to their run-time addresses as rigid
2547 units; their length does not change and neither does the order of bytes
2548 within them. Such a rigid unit is called a @emph{section}. Assigning
2549 run-time addresses to sections is called @dfn{relocation}. It includes
2550 the task of adjusting mentions of object-file addresses so they refer to
2551 the proper run-time addresses.
2553 For the H8/300 and H8/500,
2554 and for the Hitachi SH,
2555 @command{@value{AS}} pads sections if needed to
2556 ensure they end on a word (sixteen bit) boundary.
2559 @cindex standard assembler sections
2560 An object file written by @command{@value{AS}} has at least three sections, any
2561 of which may be empty. These are named @dfn{text}, @dfn{data} and
2566 When it generates COFF output,
2568 @command{@value{AS}} can also generate whatever other named sections you specify
2569 using the @samp{.section} directive (@pxref{Section,,@code{.section}}).
2570 If you do not use any directives that place output in the @samp{.text}
2571 or @samp{.data} sections, these sections still exist, but are empty.
2576 When @command{@value{AS}} generates SOM or ELF output for the HPPA,
2578 @command{@value{AS}} can also generate whatever other named sections you
2579 specify using the @samp{.space} and @samp{.subspace} directives. See
2580 @cite{HP9000 Series 800 Assembly Language Reference Manual}
2581 (HP 92432-90001) for details on the @samp{.space} and @samp{.subspace}
2582 assembler directives.
2585 Additionally, @command{@value{AS}} uses different names for the standard
2586 text, data, and bss sections when generating SOM output. Program text
2587 is placed into the @samp{$CODE$} section, data into @samp{$DATA$}, and
2588 BSS into @samp{$BSS$}.
2592 Within the object file, the text section starts at address @code{0}, the
2593 data section follows, and the bss section follows the data section.
2596 When generating either SOM or ELF output files on the HPPA, the text
2597 section starts at address @code{0}, the data section at address
2598 @code{0x4000000}, and the bss section follows the data section.
2601 To let @code{@value{LD}} know which data changes when the sections are
2602 relocated, and how to change that data, @command{@value{AS}} also writes to the
2603 object file details of the relocation needed. To perform relocation
2604 @code{@value{LD}} must know, each time an address in the object
2608 Where in the object file is the beginning of this reference to
2611 How long (in bytes) is this reference?
2613 Which section does the address refer to? What is the numeric value of
2615 (@var{address}) @minus{} (@var{start-address of section})?
2618 Is the reference to an address ``Program-Counter relative''?
2621 @cindex addresses, format of
2622 @cindex section-relative addressing
2623 In fact, every address @command{@value{AS}} ever uses is expressed as
2625 (@var{section}) + (@var{offset into section})
2628 Further, most expressions @command{@value{AS}} computes have this section-relative
2631 (For some object formats, such as SOM for the HPPA, some expressions are
2632 symbol-relative instead.)
2635 In this manual we use the notation @{@var{secname} @var{N}@} to mean ``offset
2636 @var{N} into section @var{secname}.''
2638 Apart from text, data and bss sections you need to know about the
2639 @dfn{absolute} section. When @code{@value{LD}} mixes partial programs,
2640 addresses in the absolute section remain unchanged. For example, address
2641 @code{@{absolute 0@}} is ``relocated'' to run-time address 0 by
2642 @code{@value{LD}}. Although the linker never arranges two partial programs'
2643 data sections with overlapping addresses after linking, @emph{by definition}
2644 their absolute sections must overlap. Address @code{@{absolute@ 239@}} in one
2645 part of a program is always the same address when the program is running as
2646 address @code{@{absolute@ 239@}} in any other part of the program.
2648 The idea of sections is extended to the @dfn{undefined} section. Any
2649 address whose section is unknown at assembly time is by definition
2650 rendered @{undefined @var{U}@}---where @var{U} is filled in later.
2651 Since numbers are always defined, the only way to generate an undefined
2652 address is to mention an undefined symbol. A reference to a named
2653 common block would be such a symbol: its value is unknown at assembly
2654 time so it has section @emph{undefined}.
2656 By analogy the word @emph{section} is used to describe groups of sections in
2657 the linked program. @code{@value{LD}} puts all partial programs' text
2658 sections in contiguous addresses in the linked program. It is
2659 customary to refer to the @emph{text section} of a program, meaning all
2660 the addresses of all partial programs' text sections. Likewise for
2661 data and bss sections.
2663 Some sections are manipulated by @code{@value{LD}}; others are invented for
2664 use of @command{@value{AS}} and have no meaning except during assembly.
2667 @section Linker Sections
2668 @code{@value{LD}} deals with just four kinds of sections, summarized below.
2673 @cindex named sections
2674 @cindex sections, named
2675 @item named sections
2678 @cindex text section
2679 @cindex data section
2683 These sections hold your program. @command{@value{AS}} and @code{@value{LD}} treat them as
2684 separate but equal sections. Anything you can say of one section is
2687 When the program is running, however, it is
2688 customary for the text section to be unalterable. The
2689 text section is often shared among processes: it contains
2690 instructions, constants and the like. The data section of a running
2691 program is usually alterable: for example, C variables would be stored
2692 in the data section.
2697 This section contains zeroed bytes when your program begins running. It
2698 is used to hold uninitialized variables or common storage. The length of
2699 each partial program's bss section is important, but because it starts
2700 out containing zeroed bytes there is no need to store explicit zero
2701 bytes in the object file. The bss section was invented to eliminate
2702 those explicit zeros from object files.
2704 @cindex absolute section
2705 @item absolute section
2706 Address 0 of this section is always ``relocated'' to runtime address 0.
2707 This is useful if you want to refer to an address that @code{@value{LD}} must
2708 not change when relocating. In this sense we speak of absolute
2709 addresses being ``unrelocatable'': they do not change during relocation.
2711 @cindex undefined section
2712 @item undefined section
2713 This ``section'' is a catch-all for address references to objects not in
2714 the preceding sections.
2715 @c FIXME: ref to some other doc on obj-file formats could go here.
2718 @cindex relocation example
2719 An idealized example of three relocatable sections follows.
2721 The example uses the traditional section names @samp{.text} and @samp{.data}.
2723 Memory addresses are on the horizontal axis.
2727 @c END TEXI2ROFF-KILL
2730 partial program # 1: |ttttt|dddd|00|
2737 partial program # 2: |TTT|DDD|000|
2740 +--+---+-----+--+----+---+-----+~~
2741 linked program: | |TTT|ttttt| |dddd|DDD|00000|
2742 +--+---+-----+--+----+---+-----+~~
2744 addresses: 0 @dots{}
2751 \line{\it Partial program \#1: \hfil}
2752 \line{\ibox{2.5cm}{\tt text}\ibox{2cm}{\tt data}\ibox{1cm}{\tt bss}\hfil}
2753 \line{\boxit{2.5cm}{\tt ttttt}\boxit{2cm}{\tt dddd}\boxit{1cm}{\tt 00}\hfil}
2755 \line{\it Partial program \#2: \hfil}
2756 \line{\ibox{1cm}{\tt text}\ibox{1.5cm}{\tt data}\ibox{1cm}{\tt bss}\hfil}
2757 \line{\boxit{1cm}{\tt TTT}\boxit{1.5cm}{\tt DDDD}\boxit{1cm}{\tt 000}\hfil}
2759 \line{\it linked program: \hfil}
2760 \line{\ibox{.5cm}{}\ibox{1cm}{\tt text}\ibox{2.5cm}{}\ibox{.75cm}{}\ibox{2cm}{\tt data}\ibox{1.5cm}{}\ibox{2cm}{\tt bss}\hfil}
2761 \line{\boxit{.5cm}{}\boxit{1cm}{\tt TTT}\boxit{2.5cm}{\tt
2762 ttttt}\boxit{.75cm}{}\boxit{2cm}{\tt dddd}\boxit{1.5cm}{\tt
2763 DDDD}\boxit{2cm}{\tt 00000}\ \dots\hfil}
2765 \line{\it addresses: \hfil}
2769 @c END TEXI2ROFF-KILL
2772 @section Assembler Internal Sections
2774 @cindex internal assembler sections
2775 @cindex sections in messages, internal
2776 These sections are meant only for the internal use of @command{@value{AS}}. They
2777 have no meaning at run-time. You do not really need to know about these
2778 sections for most purposes; but they can be mentioned in @command{@value{AS}}
2779 warning messages, so it might be helpful to have an idea of their
2780 meanings to @command{@value{AS}}. These sections are used to permit the
2781 value of every expression in your assembly language program to be a
2782 section-relative address.
2785 @cindex assembler internal logic error
2786 @item ASSEMBLER-INTERNAL-LOGIC-ERROR!
2787 An internal assembler logic error has been found. This means there is a
2788 bug in the assembler.
2790 @cindex expr (internal section)
2792 The assembler stores complex expression internally as combinations of
2793 symbols. When it needs to represent an expression as a symbol, it puts
2794 it in the expr section.
2796 @c FIXME item transfer[t] vector preload
2797 @c FIXME item transfer[t] vector postload
2798 @c FIXME item register
2802 @section Sub-Sections
2804 @cindex numbered subsections
2805 @cindex grouping data
2811 fall into two sections: text and data.
2813 You may have separate groups of
2815 data in named sections
2819 data in named sections
2825 that you want to end up near to each other in the object file, even though they
2826 are not contiguous in the assembler source. @command{@value{AS}} allows you to
2827 use @dfn{subsections} for this purpose. Within each section, there can be
2828 numbered subsections with values from 0 to 8192. Objects assembled into the
2829 same subsection go into the object file together with other objects in the same
2830 subsection. For example, a compiler might want to store constants in the text
2831 section, but might not want to have them interspersed with the program being
2832 assembled. In this case, the compiler could issue a @samp{.text 0} before each
2833 section of code being output, and a @samp{.text 1} before each group of
2834 constants being output.
2836 Subsections are optional. If you do not use subsections, everything
2837 goes in subsection number zero.
2840 Each subsection is zero-padded up to a multiple of four bytes.
2841 (Subsections may be padded a different amount on different flavors
2842 of @command{@value{AS}}.)
2846 On the H8/300 and H8/500 platforms, each subsection is zero-padded to a word
2847 boundary (two bytes).
2848 The same is true on the Hitachi SH.
2851 @c FIXME section padding (alignment)?
2852 @c Rich Pixley says padding here depends on target obj code format; that
2853 @c doesn't seem particularly useful to say without further elaboration,
2854 @c so for now I say nothing about it. If this is a generic BFD issue,
2855 @c these paragraphs might need to vanish from this manual, and be
2856 @c discussed in BFD chapter of binutils (or some such).
2859 On the AMD 29K family, no particular padding is added to section or
2860 subsection sizes; @value{AS} forces no alignment on this platform.
2864 Subsections appear in your object file in numeric order, lowest numbered
2865 to highest. (All this to be compatible with other people's assemblers.)
2866 The object file contains no representation of subsections; @code{@value{LD}} and
2867 other programs that manipulate object files see no trace of them.
2868 They just see all your text subsections as a text section, and all your
2869 data subsections as a data section.
2871 To specify which subsection you want subsequent statements assembled
2872 into, use a numeric argument to specify it, in a @samp{.text
2873 @var{expression}} or a @samp{.data @var{expression}} statement.
2876 When generating COFF output, you
2881 can also use an extra subsection
2882 argument with arbitrary named sections: @samp{.section @var{name},
2885 @var{Expression} should be an absolute expression.
2886 (@xref{Expressions}.) If you just say @samp{.text} then @samp{.text 0}
2887 is assumed. Likewise @samp{.data} means @samp{.data 0}. Assembly
2888 begins in @code{text 0}. For instance:
2890 .text 0 # The default subsection is text 0 anyway.
2891 .ascii "This lives in the first text subsection. *"
2893 .ascii "But this lives in the second text subsection."
2895 .ascii "This lives in the data section,"
2896 .ascii "in the first data subsection."
2898 .ascii "This lives in the first text section,"
2899 .ascii "immediately following the asterisk (*)."
2902 Each section has a @dfn{location counter} incremented by one for every byte
2903 assembled into that section. Because subsections are merely a convenience
2904 restricted to @command{@value{AS}} there is no concept of a subsection location
2905 counter. There is no way to directly manipulate a location counter---but the
2906 @code{.align} directive changes it, and any label definition captures its
2907 current value. The location counter of the section where statements are being
2908 assembled is said to be the @dfn{active} location counter.
2911 @section bss Section
2914 @cindex common variable storage
2915 The bss section is used for local common variable storage.
2916 You may allocate address space in the bss section, but you may
2917 not dictate data to load into it before your program executes. When
2918 your program starts running, all the contents of the bss
2919 section are zeroed bytes.
2921 The @code{.lcomm} pseudo-op defines a symbol in the bss section; see
2922 @ref{Lcomm,,@code{.lcomm}}.
2924 The @code{.comm} pseudo-op may be used to declare a common symbol, which is
2925 another form of uninitialized symbol; see @xref{Comm,,@code{.comm}}.
2928 When assembling for a target which supports multiple sections, such as ELF or
2929 COFF, you may switch into the @code{.bss} section and define symbols as usual;
2930 see @ref{Section,,@code{.section}}. You may only assemble zero values into the
2931 section. Typically the section will only contain symbol definitions and
2932 @code{.skip} directives (@pxref{Skip,,@code{.skip}}).
2939 Symbols are a central concept: the programmer uses symbols to name
2940 things, the linker uses symbols to link, and the debugger uses symbols
2944 @cindex debuggers, and symbol order
2945 @emph{Warning:} @command{@value{AS}} does not place symbols in the object file in
2946 the same order they were declared. This may break some debuggers.
2951 * Setting Symbols:: Giving Symbols Other Values
2952 * Symbol Names:: Symbol Names
2953 * Dot:: The Special Dot Symbol
2954 * Symbol Attributes:: Symbol Attributes
2961 A @dfn{label} is written as a symbol immediately followed by a colon
2962 @samp{:}. The symbol then represents the current value of the
2963 active location counter, and is, for example, a suitable instruction
2964 operand. You are warned if you use the same symbol to represent two
2965 different locations: the first definition overrides any other
2969 On the HPPA, the usual form for a label need not be immediately followed by a
2970 colon, but instead must start in column zero. Only one label may be defined on
2971 a single line. To work around this, the HPPA version of @command{@value{AS}} also
2972 provides a special directive @code{.label} for defining labels more flexibly.
2975 @node Setting Symbols
2976 @section Giving Symbols Other Values
2978 @cindex assigning values to symbols
2979 @cindex symbol values, assigning
2980 A symbol can be given an arbitrary value by writing a symbol, followed
2981 by an equals sign @samp{=}, followed by an expression
2982 (@pxref{Expressions}). This is equivalent to using the @code{.set}
2983 directive. @xref{Set,,@code{.set}}.
2986 @section Symbol Names
2988 @cindex symbol names
2989 @cindex names, symbol
2990 @ifclear SPECIAL-SYMS
2991 Symbol names begin with a letter or with one of @samp{._}. On most
2992 machines, you can also use @code{$} in symbol names; exceptions are
2993 noted in @ref{Machine Dependencies}. That character may be followed by any
2994 string of digits, letters, dollar signs (unless otherwise noted in
2995 @ref{Machine Dependencies}), and underscores.
2998 For the AMD 29K family, @samp{?} is also allowed in the
2999 body of a symbol name, though not at its beginning.
3004 Symbol names begin with a letter or with one of @samp{._}. On the
3006 H8/500, you can also use @code{$} in symbol names. That character may
3007 be followed by any string of digits, letters, dollar signs (save on the
3008 H8/300), and underscores.
3012 Case of letters is significant: @code{foo} is a different symbol name
3015 Each symbol has exactly one name. Each name in an assembly language program
3016 refers to exactly one symbol. You may use that symbol name any number of times
3019 @subheading Local Symbol Names
3021 @cindex local symbol names
3022 @cindex symbol names, local
3023 @cindex temporary symbol names
3024 @cindex symbol names, temporary
3025 Local symbols help compilers and programmers use names temporarily.
3026 They create symbols which are guaranteed to be unique over the entire scope of
3027 the input source code and which can be referred to by a simple notation.
3028 To define a local symbol, write a label of the form @samp{@b{N}:} (where @b{N}
3029 represents any positive integer). To refer to the most recent previous
3030 definition of that symbol write @samp{@b{N}b}, using the same number as when
3031 you defined the label. To refer to the next definition of a local label, write
3032 @samp{@b{N}f}--- The @samp{b} stands for``backwards'' and the @samp{f} stands
3035 There is no restriction on how you can use these labels, and you can reuse them
3036 too. So that it is possible to repeatedly define the same local label (using
3037 the same number @samp{@b{N}}), although you can only refer to the most recently
3038 defined local label of that number (for a backwards reference) or the next
3039 definition of a specific local label for a forward reference. It is also worth
3040 noting that the first 10 local labels (@samp{@b{0:}}@dots{}@samp{@b{9:}}) are
3041 implemented in a slightly more efficient manner than the others.
3052 Which is the equivalent of:
3055 label_1: branch label_3
3056 label_2: branch label_1
3057 label_3: branch label_4
3058 label_4: branch label_3
3061 Local symbol names are only a notational device. They are immediately
3062 transformed into more conventional symbol names before the assembler uses them.
3063 The symbol names stored in the symbol table, appearing in error messages and
3064 optionally emitted to the object file. The names are constructed using these
3069 All local labels begin with @samp{L}. Normally both @command{@value{AS}} and
3070 @code{@value{LD}} forget symbols that start with @samp{L}. These labels are
3071 used for symbols you are never intended to see. If you use the
3072 @samp{-L} option then @command{@value{AS}} retains these symbols in the
3073 object file. If you also instruct @code{@value{LD}} to retain these symbols,
3074 you may use them in debugging.
3077 This is the number that was used in the local label definition. So if the
3078 label is written @samp{55:} then the number is @samp{55}.
3081 This unusual character is included so you do not accidentally invent a symbol
3082 of the same name. The character has ASCII value of @samp{\002} (control-B).
3084 @item @emph{ordinal number}
3085 This is a serial number to keep the labels distinct. The first definition of
3086 @samp{0:} gets the number @samp{1}. The 15th definition of @samp{0:} gets the
3087 number @samp{15}, and so on. Likewise the first definition of @samp{1:} gets
3088 the number @samp{1} and its 15th defintion gets @samp{15} as well.
3091 So for example, the first @code{1:} is named @code{L1@kbd{C-B}1}, the 44th
3092 @code{3:} is named @code{L3@kbd{C-B}44}.
3094 @subheading Dollar Local Labels
3095 @cindex dollar local symbols
3097 @code{@value{AS}} also supports an even more local form of local labels called
3098 dollar labels. These labels go out of scope (ie they become undefined) as soon
3099 as a non-local label is defined. Thus they remain valid for only a small
3100 region of the input source code. Normal local labels, by contrast, remain in
3101 scope for the entire file, or until they are redefined by another occurrence of
3102 the same local label.
3104 Dollar labels are defined in exactly the same way as ordinary local labels,
3105 except that instead of being terminated by a colon, they are terminated by a
3106 dollar sign. eg @samp{@b{55$}}.
3108 They can also be distinguished from ordinary local labels by their transformed
3109 name which uses ASCII character @samp{\001} (control-A) as the magic character
3110 to distinguish them from ordinary labels. Thus the 5th defintion of @samp{6$}
3111 is named @samp{L6@kbd{C-A}5}.
3114 @section The Special Dot Symbol
3116 @cindex dot (symbol)
3117 @cindex @code{.} (symbol)
3118 @cindex current address
3119 @cindex location counter
3120 The special symbol @samp{.} refers to the current address that
3121 @command{@value{AS}} is assembling into. Thus, the expression @samp{melvin:
3122 .long .} defines @code{melvin} to contain its own address.
3123 Assigning a value to @code{.} is treated the same as a @code{.org}
3124 directive. Thus, the expression @samp{.=.+4} is the same as saying
3125 @ifclear no-space-dir
3134 @node Symbol Attributes
3135 @section Symbol Attributes
3137 @cindex symbol attributes
3138 @cindex attributes, symbol
3139 Every symbol has, as well as its name, the attributes ``Value'' and
3140 ``Type''. Depending on output format, symbols can also have auxiliary
3143 The detailed definitions are in @file{a.out.h}.
3146 If you use a symbol without defining it, @command{@value{AS}} assumes zero for
3147 all these attributes, and probably won't warn you. This makes the
3148 symbol an externally defined symbol, which is generally what you
3152 * Symbol Value:: Value
3153 * Symbol Type:: Type
3156 * a.out Symbols:: Symbol Attributes: @code{a.out}
3160 * a.out Symbols:: Symbol Attributes: @code{a.out}
3163 * a.out Symbols:: Symbol Attributes: @code{a.out}, @code{b.out}
3168 * COFF Symbols:: Symbol Attributes for COFF
3171 * SOM Symbols:: Symbol Attributes for SOM
3178 @cindex value of a symbol
3179 @cindex symbol value
3180 The value of a symbol is (usually) 32 bits. For a symbol which labels a
3181 location in the text, data, bss or absolute sections the value is the
3182 number of addresses from the start of that section to the label.
3183 Naturally for text, data and bss sections the value of a symbol changes
3184 as @code{@value{LD}} changes section base addresses during linking. Absolute
3185 symbols' values do not change during linking: that is why they are
3188 The value of an undefined symbol is treated in a special way. If it is
3189 0 then the symbol is not defined in this assembler source file, and
3190 @code{@value{LD}} tries to determine its value from other files linked into the
3191 same program. You make this kind of symbol simply by mentioning a symbol
3192 name without defining it. A non-zero value represents a @code{.comm}
3193 common declaration. The value is how much common storage to reserve, in
3194 bytes (addresses). The symbol refers to the first address of the
3200 @cindex type of a symbol
3202 The type attribute of a symbol contains relocation (section)
3203 information, any flag settings indicating that a symbol is external, and
3204 (optionally), other information for linkers and debuggers. The exact
3205 format depends on the object-code output format in use.
3210 @c The following avoids a "widow" subsection title. @group would be
3211 @c better if it were available outside examples.
3214 @subsection Symbol Attributes: @code{a.out}, @code{b.out}
3216 @cindex @code{b.out} symbol attributes
3217 @cindex symbol attributes, @code{b.out}
3218 These symbol attributes appear only when @command{@value{AS}} is configured for
3219 one of the Berkeley-descended object output formats---@code{a.out} or
3225 @subsection Symbol Attributes: @code{a.out}
3227 @cindex @code{a.out} symbol attributes
3228 @cindex symbol attributes, @code{a.out}
3234 @subsection Symbol Attributes: @code{a.out}
3236 @cindex @code{a.out} symbol attributes
3237 @cindex symbol attributes, @code{a.out}
3241 * Symbol Desc:: Descriptor
3242 * Symbol Other:: Other
3246 @subsubsection Descriptor
3248 @cindex descriptor, of @code{a.out} symbol
3249 This is an arbitrary 16-bit value. You may establish a symbol's
3250 descriptor value by using a @code{.desc} statement
3251 (@pxref{Desc,,@code{.desc}}). A descriptor value means nothing to
3252 @command{@value{AS}}.
3255 @subsubsection Other
3257 @cindex other attribute, of @code{a.out} symbol
3258 This is an arbitrary 8-bit value. It means nothing to @command{@value{AS}}.
3263 @subsection Symbol Attributes for COFF
3265 @cindex COFF symbol attributes
3266 @cindex symbol attributes, COFF
3268 The COFF format supports a multitude of auxiliary symbol attributes;
3269 like the primary symbol attributes, they are set between @code{.def} and
3270 @code{.endef} directives.
3272 @subsubsection Primary Attributes
3274 @cindex primary attributes, COFF symbols
3275 The symbol name is set with @code{.def}; the value and type,
3276 respectively, with @code{.val} and @code{.type}.
3278 @subsubsection Auxiliary Attributes
3280 @cindex auxiliary attributes, COFF symbols
3281 The @command{@value{AS}} directives @code{.dim}, @code{.line}, @code{.scl},
3282 @code{.size}, and @code{.tag} can generate auxiliary symbol table
3283 information for COFF.
3288 @subsection Symbol Attributes for SOM
3290 @cindex SOM symbol attributes
3291 @cindex symbol attributes, SOM
3293 The SOM format for the HPPA supports a multitude of symbol attributes set with
3294 the @code{.EXPORT} and @code{.IMPORT} directives.
3296 The attributes are described in @cite{HP9000 Series 800 Assembly
3297 Language Reference Manual} (HP 92432-90001) under the @code{IMPORT} and
3298 @code{EXPORT} assembler directive documentation.
3302 @chapter Expressions
3306 @cindex numeric values
3307 An @dfn{expression} specifies an address or numeric value.
3308 Whitespace may precede and/or follow an expression.
3310 The result of an expression must be an absolute number, or else an offset into
3311 a particular section. If an expression is not absolute, and there is not
3312 enough information when @command{@value{AS}} sees the expression to know its
3313 section, a second pass over the source program might be necessary to interpret
3314 the expression---but the second pass is currently not implemented.
3315 @command{@value{AS}} aborts with an error message in this situation.
3318 * Empty Exprs:: Empty Expressions
3319 * Integer Exprs:: Integer Expressions
3323 @section Empty Expressions
3325 @cindex empty expressions
3326 @cindex expressions, empty
3327 An empty expression has no value: it is just whitespace or null.
3328 Wherever an absolute expression is required, you may omit the
3329 expression, and @command{@value{AS}} assumes a value of (absolute) 0. This
3330 is compatible with other assemblers.
3333 @section Integer Expressions
3335 @cindex integer expressions
3336 @cindex expressions, integer
3337 An @dfn{integer expression} is one or more @emph{arguments} delimited
3338 by @emph{operators}.
3341 * Arguments:: Arguments
3342 * Operators:: Operators
3343 * Prefix Ops:: Prefix Operators
3344 * Infix Ops:: Infix Operators
3348 @subsection Arguments
3350 @cindex expression arguments
3351 @cindex arguments in expressions
3352 @cindex operands in expressions
3353 @cindex arithmetic operands
3354 @dfn{Arguments} are symbols, numbers or subexpressions. In other
3355 contexts arguments are sometimes called ``arithmetic operands''. In
3356 this manual, to avoid confusing them with the ``instruction operands'' of
3357 the machine language, we use the term ``argument'' to refer to parts of
3358 expressions only, reserving the word ``operand'' to refer only to machine
3359 instruction operands.
3361 Symbols are evaluated to yield @{@var{section} @var{NNN}@} where
3362 @var{section} is one of text, data, bss, absolute,
3363 or undefined. @var{NNN} is a signed, 2's complement 32 bit
3366 Numbers are usually integers.
3368 A number can be a flonum or bignum. In this case, you are warned
3369 that only the low order 32 bits are used, and @command{@value{AS}} pretends
3370 these 32 bits are an integer. You may write integer-manipulating
3371 instructions that act on exotic constants, compatible with other
3374 @cindex subexpressions
3375 Subexpressions are a left parenthesis @samp{(} followed by an integer
3376 expression, followed by a right parenthesis @samp{)}; or a prefix
3377 operator followed by an argument.
3380 @subsection Operators
3382 @cindex operators, in expressions
3383 @cindex arithmetic functions
3384 @cindex functions, in expressions
3385 @dfn{Operators} are arithmetic functions, like @code{+} or @code{%}. Prefix
3386 operators are followed by an argument. Infix operators appear
3387 between their arguments. Operators may be preceded and/or followed by
3391 @subsection Prefix Operator
3393 @cindex prefix operators
3394 @command{@value{AS}} has the following @dfn{prefix operators}. They each take
3395 one argument, which must be absolute.
3397 @c the tex/end tex stuff surrounding this small table is meant to make
3398 @c it align, on the printed page, with the similar table in the next
3399 @c section (which is inside an enumerate).
3401 \global\advance\leftskip by \itemindent
3406 @dfn{Negation}. Two's complement negation.
3408 @dfn{Complementation}. Bitwise not.
3412 \global\advance\leftskip by -\itemindent
3416 @subsection Infix Operators
3418 @cindex infix operators
3419 @cindex operators, permitted arguments
3420 @dfn{Infix operators} take two arguments, one on either side. Operators
3421 have precedence, but operations with equal precedence are performed left
3422 to right. Apart from @code{+} or @option{-}, both arguments must be
3423 absolute, and the result is absolute.
3426 @cindex operator precedence
3427 @cindex precedence of operators
3434 @dfn{Multiplication}.
3437 @dfn{Division}. Truncation is the same as the C operator @samp{/}
3444 @dfn{Shift Left}. Same as the C operator @samp{<<}.
3448 @dfn{Shift Right}. Same as the C operator @samp{>>}.
3452 Intermediate precedence
3457 @dfn{Bitwise Inclusive Or}.
3463 @dfn{Bitwise Exclusive Or}.
3466 @dfn{Bitwise Or Not}.
3473 @cindex addition, permitted arguments
3474 @cindex plus, permitted arguments
3475 @cindex arguments for addition
3477 @dfn{Addition}. If either argument is absolute, the result has the section of
3478 the other argument. You may not add together arguments from different
3481 @cindex subtraction, permitted arguments
3482 @cindex minus, permitted arguments
3483 @cindex arguments for subtraction
3485 @dfn{Subtraction}. If the right argument is absolute, the
3486 result has the section of the left argument.
3487 If both arguments are in the same section, the result is absolute.
3488 You may not subtract arguments from different sections.
3489 @c FIXME is there still something useful to say about undefined - undefined ?
3491 @cindex comparison expressions
3492 @cindex expressions, comparison
3496 @dfn{Is Not Equal To}
3500 @dfn{Is Greater Than}
3502 @dfn{Is Greater Than Or Equal To}
3504 @dfn{Is Less Than Or Equal To}
3506 The comparison operators can be used as infix operators. A true results has a
3507 value of -1 whereas a false result has a value of 0. Note, these operators
3508 perform signed comparisons.
3511 @item Lowest Precedence
3520 These two logical operations can be used to combine the results of sub
3521 expressions. Note, unlike the comparison operators a true result returns a
3522 value of 1 but a false results does still return 0. Also note that the logical
3523 or operator has a slightly lower precedence than logical and.
3528 In short, it's only meaningful to add or subtract the @emph{offsets} in an
3529 address; you can only have a defined section in one of the two arguments.
3532 @chapter Assembler Directives
3534 @cindex directives, machine independent
3535 @cindex pseudo-ops, machine independent
3536 @cindex machine independent directives
3537 All assembler directives have names that begin with a period (@samp{.}).
3538 The rest of the name is letters, usually in lower case.
3540 This chapter discusses directives that are available regardless of the
3541 target machine configuration for the @sc{gnu} assembler.
3543 Some machine configurations provide additional directives.
3544 @xref{Machine Dependencies}.
3547 @ifset machine-directives
3548 @xref{Machine Dependencies} for additional directives.
3553 * Abort:: @code{.abort}
3555 * ABORT:: @code{.ABORT}
3558 * Align:: @code{.align @var{abs-expr} , @var{abs-expr}}
3559 * Ascii:: @code{.ascii "@var{string}"}@dots{}
3560 * Asciz:: @code{.asciz "@var{string}"}@dots{}
3561 * Balign:: @code{.balign @var{abs-expr} , @var{abs-expr}}
3562 * Byte:: @code{.byte @var{expressions}}
3563 * Comm:: @code{.comm @var{symbol} , @var{length} }
3564 * Data:: @code{.data @var{subsection}}
3566 * Def:: @code{.def @var{name}}
3569 * Desc:: @code{.desc @var{symbol}, @var{abs-expression}}
3575 * Double:: @code{.double @var{flonums}}
3576 * Eject:: @code{.eject}
3577 * Else:: @code{.else}
3578 * Elseif:: @code{.elseif}
3581 * Endef:: @code{.endef}
3584 * Endfunc:: @code{.endfunc}
3585 * Endif:: @code{.endif}
3586 * Equ:: @code{.equ @var{symbol}, @var{expression}}
3587 * Equiv:: @code{.equiv @var{symbol}, @var{expression}}
3589 * Exitm:: @code{.exitm}
3590 * Extern:: @code{.extern}
3591 * Fail:: @code{.fail}
3592 @ifclear no-file-dir
3593 * File:: @code{.file @var{string}}
3596 * Fill:: @code{.fill @var{repeat} , @var{size} , @var{value}}
3597 * Float:: @code{.float @var{flonums}}
3598 * Func:: @code{.func}
3599 * Global:: @code{.global @var{symbol}}, @code{.globl @var{symbol}}
3601 * Hidden:: @code{.hidden @var{names}}
3604 * hword:: @code{.hword @var{expressions}}
3605 * Ident:: @code{.ident}
3606 * If:: @code{.if @var{absolute expression}}
3607 * Incbin:: @code{.incbin "@var{file}"[,@var{skip}[,@var{count}]]}
3608 * Include:: @code{.include "@var{file}"}
3609 * Int:: @code{.int @var{expressions}}
3611 * Internal:: @code{.internal @var{names}}
3614 * Irp:: @code{.irp @var{symbol},@var{values}}@dots{}
3615 * Irpc:: @code{.irpc @var{symbol},@var{values}}@dots{}
3616 * Lcomm:: @code{.lcomm @var{symbol} , @var{length}}
3617 * Lflags:: @code{.lflags}
3618 @ifclear no-line-dir
3619 * Line:: @code{.line @var{line-number}}
3622 * Ln:: @code{.ln @var{line-number}}
3623 * Linkonce:: @code{.linkonce [@var{type}]}
3624 * List:: @code{.list}
3625 * Long:: @code{.long @var{expressions}}
3627 * Lsym:: @code{.lsym @var{symbol}, @var{expression}}
3630 * Macro:: @code{.macro @var{name} @var{args}}@dots{}
3631 * MRI:: @code{.mri @var{val}}
3632 * Nolist:: @code{.nolist}
3633 * Octa:: @code{.octa @var{bignums}}
3634 * Org:: @code{.org @var{new-lc} , @var{fill}}
3635 * P2align:: @code{.p2align @var{abs-expr} , @var{abs-expr}}
3637 * PopSection:: @code{.popsection}
3638 * Previous:: @code{.previous}
3641 * Print:: @code{.print @var{string}}
3643 * Protected:: @code{.protected @var{names}}
3646 * Psize:: @code{.psize @var{lines}, @var{columns}}
3647 * Purgem:: @code{.purgem @var{name}}
3649 * PushSection:: @code{.pushsection @var{name}}
3652 * Quad:: @code{.quad @var{bignums}}
3653 * Rept:: @code{.rept @var{count}}
3654 * Sbttl:: @code{.sbttl "@var{subheading}"}
3656 * Scl:: @code{.scl @var{class}}
3657 * Section:: @code{.section @var{name}, @var{subsection}}
3660 * Set:: @code{.set @var{symbol}, @var{expression}}
3661 * Short:: @code{.short @var{expressions}}
3662 * Single:: @code{.single @var{flonums}}
3663 * Size:: @code{.size [@var{name} , @var{expression}]}
3664 * Skip:: @code{.skip @var{size} , @var{fill}}
3665 * Sleb128:: @code{.sleb128 @var{expressions}}
3666 * Space:: @code{.space @var{size} , @var{fill}}
3668 * Stab:: @code{.stabd, .stabn, .stabs}
3671 * String:: @code{.string "@var{str}"}
3672 * Struct:: @code{.struct @var{expression}}
3674 * SubSection:: @code{.subsection}
3675 * Symver:: @code{.symver @var{name},@var{name2@@nodename}}
3679 * Tag:: @code{.tag @var{structname}}
3682 * Text:: @code{.text @var{subsection}}
3683 * Title:: @code{.title "@var{heading}"}
3684 * Type:: @code{.type <@var{int} | @var{name} , @var{type description}>}
3685 * Uleb128:: @code{.uleb128 @var{expressions}}
3687 * Val:: @code{.val @var{addr}}
3691 * Version:: @code{.version "@var{string}"}
3692 * VTableEntry:: @code{.vtable_entry @var{table}, @var{offset}}
3693 * VTableInherit:: @code{.vtable_inherit @var{child}, @var{parent}}
3694 * Weak:: @code{.weak @var{names}}
3697 * Word:: @code{.word @var{expressions}}
3698 * Deprecated:: Deprecated Directives
3702 @section @code{.abort}
3704 @cindex @code{abort} directive
3705 @cindex stopping the assembly
3706 This directive stops the assembly immediately. It is for
3707 compatibility with other assemblers. The original idea was that the
3708 assembly language source would be piped into the assembler. If the sender
3709 of the source quit, it could use this directive tells @command{@value{AS}} to
3710 quit also. One day @code{.abort} will not be supported.
3714 @section @code{.ABORT}
3716 @cindex @code{ABORT} directive
3717 When producing COFF output, @command{@value{AS}} accepts this directive as a
3718 synonym for @samp{.abort}.
3721 When producing @code{b.out} output, @command{@value{AS}} accepts this directive,
3727 @section @code{.align @var{abs-expr}, @var{abs-expr}, @var{abs-expr}}
3729 @cindex padding the location counter
3730 @cindex @code{align} directive
3731 Pad the location counter (in the current subsection) to a particular storage
3732 boundary. The first expression (which must be absolute) is the alignment
3733 required, as described below.
3735 The second expression (also absolute) gives the fill value to be stored in the
3736 padding bytes. It (and the comma) may be omitted. If it is omitted, the
3737 padding bytes are normally zero. However, on some systems, if the section is
3738 marked as containing code and the fill value is omitted, the space is filled
3739 with no-op instructions.
3741 The third expression is also absolute, and is also optional. If it is present,
3742 it is the maximum number of bytes that should be skipped by this alignment
3743 directive. If doing the alignment would require skipping more bytes than the
3744 specified maximum, then the alignment is not done at all. You can omit the
3745 fill value (the second argument) entirely by simply using two commas after the
3746 required alignment; this can be useful if you want the alignment to be filled
3747 with no-op instructions when appropriate.
3749 The way the required alignment is specified varies from system to system.
3750 For the a29k, hppa, m68k, m88k, w65, sparc, and Hitachi SH, and i386 using ELF
3752 the first expression is the
3753 alignment request in bytes. For example @samp{.align 8} advances
3754 the location counter until it is a multiple of 8. If the location counter
3755 is already a multiple of 8, no change is needed.
3757 For other systems, including the i386 using a.out format, and the arm and
3758 strongarm, it is the
3759 number of low-order zero bits the location counter must have after
3760 advancement. For example @samp{.align 3} advances the location
3761 counter until it a multiple of 8. If the location counter is already a
3762 multiple of 8, no change is needed.
3764 This inconsistency is due to the different behaviors of the various
3765 native assemblers for these systems which GAS must emulate.
3766 GAS also provides @code{.balign} and @code{.p2align} directives,
3767 described later, which have a consistent behavior across all
3768 architectures (but are specific to GAS).
3771 @section @code{.ascii "@var{string}"}@dots{}
3773 @cindex @code{ascii} directive
3774 @cindex string literals
3775 @code{.ascii} expects zero or more string literals (@pxref{Strings})
3776 separated by commas. It assembles each string (with no automatic
3777 trailing zero byte) into consecutive addresses.
3780 @section @code{.asciz "@var{string}"}@dots{}
3782 @cindex @code{asciz} directive
3783 @cindex zero-terminated strings
3784 @cindex null-terminated strings
3785 @code{.asciz} is just like @code{.ascii}, but each string is followed by
3786 a zero byte. The ``z'' in @samp{.asciz} stands for ``zero''.
3789 @section @code{.balign[wl] @var{abs-expr}, @var{abs-expr}, @var{abs-expr}}
3791 @cindex padding the location counter given number of bytes
3792 @cindex @code{balign} directive
3793 Pad the location counter (in the current subsection) to a particular
3794 storage boundary. The first expression (which must be absolute) is the
3795 alignment request in bytes. For example @samp{.balign 8} advances
3796 the location counter until it is a multiple of 8. If the location counter
3797 is already a multiple of 8, no change is needed.
3799 The second expression (also absolute) gives the fill value to be stored in the
3800 padding bytes. It (and the comma) may be omitted. If it is omitted, the
3801 padding bytes are normally zero. However, on some systems, if the section is
3802 marked as containing code and the fill value is omitted, the space is filled
3803 with no-op instructions.
3805 The third expression is also absolute, and is also optional. If it is present,
3806 it is the maximum number of bytes that should be skipped by this alignment
3807 directive. If doing the alignment would require skipping more bytes than the
3808 specified maximum, then the alignment is not done at all. You can omit the
3809 fill value (the second argument) entirely by simply using two commas after the
3810 required alignment; this can be useful if you want the alignment to be filled
3811 with no-op instructions when appropriate.
3813 @cindex @code{balignw} directive
3814 @cindex @code{balignl} directive
3815 The @code{.balignw} and @code{.balignl} directives are variants of the
3816 @code{.balign} directive. The @code{.balignw} directive treats the fill
3817 pattern as a two byte word value. The @code{.balignl} directives treats the
3818 fill pattern as a four byte longword value. For example, @code{.balignw
3819 4,0x368d} will align to a multiple of 4. If it skips two bytes, they will be
3820 filled in with the value 0x368d (the exact placement of the bytes depends upon
3821 the endianness of the processor). If it skips 1 or 3 bytes, the fill value is
3825 @section @code{.byte @var{expressions}}
3827 @cindex @code{byte} directive
3828 @cindex integers, one byte
3829 @code{.byte} expects zero or more expressions, separated by commas.
3830 Each expression is assembled into the next byte.
3833 @section @code{.comm @var{symbol} , @var{length} }
3835 @cindex @code{comm} directive
3836 @cindex symbol, common
3837 @code{.comm} declares a common symbol named @var{symbol}. When linking, a
3838 common symbol in one object file may be merged with a defined or common symbol
3839 of the same name in another object file. If @code{@value{LD}} does not see a
3840 definition for the symbol--just one or more common symbols--then it will
3841 allocate @var{length} bytes of uninitialized memory. @var{length} must be an
3842 absolute expression. If @code{@value{LD}} sees multiple common symbols with
3843 the same name, and they do not all have the same size, it will allocate space
3844 using the largest size.
3847 When using ELF, the @code{.comm} directive takes an optional third argument.
3848 This is the desired alignment of the symbol, specified as a byte boundary (for
3849 example, an alignment of 16 means that the least significant 4 bits of the
3850 address should be zero). The alignment must be an absolute expression, and it
3851 must be a power of two. If @code{@value{LD}} allocates uninitialized memory
3852 for the common symbol, it will use the alignment when placing the symbol. If
3853 no alignment is specified, @command{@value{AS}} will set the alignment to the
3854 largest power of two less than or equal to the size of the symbol, up to a
3859 The syntax for @code{.comm} differs slightly on the HPPA. The syntax is
3860 @samp{@var{symbol} .comm, @var{length}}; @var{symbol} is optional.
3864 @section @code{.data @var{subsection}}
3866 @cindex @code{data} directive
3867 @code{.data} tells @command{@value{AS}} to assemble the following statements onto the
3868 end of the data subsection numbered @var{subsection} (which is an
3869 absolute expression). If @var{subsection} is omitted, it defaults
3874 @section @code{.def @var{name}}
3876 @cindex @code{def} directive
3877 @cindex COFF symbols, debugging
3878 @cindex debugging COFF symbols
3879 Begin defining debugging information for a symbol @var{name}; the
3880 definition extends until the @code{.endef} directive is encountered.
3883 This directive is only observed when @command{@value{AS}} is configured for COFF
3884 format output; when producing @code{b.out}, @samp{.def} is recognized,
3891 @section @code{.desc @var{symbol}, @var{abs-expression}}
3893 @cindex @code{desc} directive
3894 @cindex COFF symbol descriptor
3895 @cindex symbol descriptor, COFF
3896 This directive sets the descriptor of the symbol (@pxref{Symbol Attributes})
3897 to the low 16 bits of an absolute expression.
3900 The @samp{.desc} directive is not available when @command{@value{AS}} is
3901 configured for COFF output; it is only for @code{a.out} or @code{b.out}
3902 object format. For the sake of compatibility, @command{@value{AS}} accepts
3903 it, but produces no output, when configured for COFF.
3909 @section @code{.dim}
3911 @cindex @code{dim} directive
3912 @cindex COFF auxiliary symbol information
3913 @cindex auxiliary symbol information, COFF
3914 This directive is generated by compilers to include auxiliary debugging
3915 information in the symbol table. It is only permitted inside
3916 @code{.def}/@code{.endef} pairs.
3919 @samp{.dim} is only meaningful when generating COFF format output; when
3920 @command{@value{AS}} is generating @code{b.out}, it accepts this directive but
3926 @section @code{.double @var{flonums}}
3928 @cindex @code{double} directive
3929 @cindex floating point numbers (double)
3930 @code{.double} expects zero or more flonums, separated by commas. It
3931 assembles floating point numbers.
3933 The exact kind of floating point numbers emitted depends on how
3934 @command{@value{AS}} is configured. @xref{Machine Dependencies}.
3938 On the @value{TARGET} family @samp{.double} emits 64-bit floating-point numbers
3939 in @sc{ieee} format.
3944 @section @code{.eject}
3946 @cindex @code{eject} directive
3947 @cindex new page, in listings
3948 @cindex page, in listings
3949 @cindex listing control: new page
3950 Force a page break at this point, when generating assembly listings.
3953 @section @code{.else}
3955 @cindex @code{else} directive
3956 @code{.else} is part of the @command{@value{AS}} support for conditional
3957 assembly; @pxref{If,,@code{.if}}. It marks the beginning of a section
3958 of code to be assembled if the condition for the preceding @code{.if}
3962 @section @code{.elseif}
3964 @cindex @code{elseif} directive
3965 @code{.elseif} is part of the @command{@value{AS}} support for conditional
3966 assembly; @pxref{If,,@code{.if}}. It is shorthand for beginning a new
3967 @code{.if} block that would otherwise fill the entire @code{.else} section.
3970 @section @code{.end}
3972 @cindex @code{end} directive
3973 @code{.end} marks the end of the assembly file. @command{@value{AS}} does not
3974 process anything in the file past the @code{.end} directive.
3978 @section @code{.endef}
3980 @cindex @code{endef} directive
3981 This directive flags the end of a symbol definition begun with
3985 @samp{.endef} is only meaningful when generating COFF format output; if
3986 @command{@value{AS}} is configured to generate @code{b.out}, it accepts this
3987 directive but ignores it.
3992 @section @code{.endfunc}
3993 @cindex @code{endfunc} directive
3994 @code{.endfunc} marks the end of a function specified with @code{.func}.
3997 @section @code{.endif}
3999 @cindex @code{endif} directive
4000 @code{.endif} is part of the @command{@value{AS}} support for conditional assembly;
4001 it marks the end of a block of code that is only assembled
4002 conditionally. @xref{If,,@code{.if}}.
4005 @section @code{.equ @var{symbol}, @var{expression}}
4007 @cindex @code{equ} directive
4008 @cindex assigning values to symbols
4009 @cindex symbols, assigning values to
4010 This directive sets the value of @var{symbol} to @var{expression}.
4011 It is synonymous with @samp{.set}; @pxref{Set,,@code{.set}}.
4014 The syntax for @code{equ} on the HPPA is
4015 @samp{@var{symbol} .equ @var{expression}}.
4019 @section @code{.equiv @var{symbol}, @var{expression}}
4020 @cindex @code{equiv} directive
4021 The @code{.equiv} directive is like @code{.equ} and @code{.set}, except that
4022 the assembler will signal an error if @var{symbol} is already defined.
4024 Except for the contents of the error message, this is roughly equivalent to
4033 @section @code{.err}
4034 @cindex @code{err} directive
4035 If @command{@value{AS}} assembles a @code{.err} directive, it will print an error
4036 message and, unless the @option{-Z} option was used, it will not generate an
4037 object file. This can be used to signal error an conditionally compiled code.
4040 @section @code{.exitm}
4041 Exit early from the current macro definition. @xref{Macro}.
4044 @section @code{.extern}
4046 @cindex @code{extern} directive
4047 @code{.extern} is accepted in the source program---for compatibility
4048 with other assemblers---but it is ignored. @command{@value{AS}} treats
4049 all undefined symbols as external.
4052 @section @code{.fail @var{expression}}
4054 @cindex @code{fail} directive
4055 Generates an error or a warning. If the value of the @var{expression} is 500
4056 or more, @command{@value{AS}} will print a warning message. If the value is less
4057 than 500, @command{@value{AS}} will print an error message. The message will
4058 include the value of @var{expression}. This can occasionally be useful inside
4059 complex nested macros or conditional assembly.
4061 @ifclear no-file-dir
4063 @section @code{.file @var{string}}
4065 @cindex @code{file} directive
4066 @cindex logical file name
4067 @cindex file name, logical
4068 @code{.file} tells @command{@value{AS}} that we are about to start a new logical
4069 file. @var{string} is the new file name. In general, the filename is
4070 recognized whether or not it is surrounded by quotes @samp{"}; but if you wish
4071 to specify an empty file name, you must give the quotes--@code{""}. This
4072 statement may go away in future: it is only recognized to be compatible with
4073 old @command{@value{AS}} programs.
4075 In some configurations of @command{@value{AS}}, @code{.file} has already been
4076 removed to avoid conflicts with other assemblers. @xref{Machine Dependencies}.
4081 @section @code{.fill @var{repeat} , @var{size} , @var{value}}
4083 @cindex @code{fill} directive
4084 @cindex writing patterns in memory
4085 @cindex patterns, writing in memory
4086 @var{repeat}, @var{size} and @var{value} are absolute expressions.
4087 This emits @var{repeat} copies of @var{size} bytes. @var{Repeat}
4088 may be zero or more. @var{Size} may be zero or more, but if it is
4089 more than 8, then it is deemed to have the value 8, compatible with
4090 other people's assemblers. The contents of each @var{repeat} bytes
4091 is taken from an 8-byte number. The highest order 4 bytes are
4092 zero. The lowest order 4 bytes are @var{value} rendered in the
4093 byte-order of an integer on the computer @command{@value{AS}} is assembling for.
4094 Each @var{size} bytes in a repetition is taken from the lowest order
4095 @var{size} bytes of this number. Again, this bizarre behavior is
4096 compatible with other people's assemblers.
4098 @var{size} and @var{value} are optional.
4099 If the second comma and @var{value} are absent, @var{value} is
4100 assumed zero. If the first comma and following tokens are absent,
4101 @var{size} is assumed to be 1.
4104 @section @code{.float @var{flonums}}
4106 @cindex floating point numbers (single)
4107 @cindex @code{float} directive
4108 This directive assembles zero or more flonums, separated by commas. It
4109 has the same effect as @code{.single}.
4111 The exact kind of floating point numbers emitted depends on how
4112 @command{@value{AS}} is configured.
4113 @xref{Machine Dependencies}.
4117 On the @value{TARGET} family, @code{.float} emits 32-bit floating point numbers
4118 in @sc{ieee} format.
4123 @section @code{.func @var{name}[,@var{label}]}
4124 @cindex @code{func} directive
4125 @code{.func} emits debugging information to denote function @var{name}, and
4126 is ignored unless the file is assembled with debugging enabled.
4127 Only @samp{--gstabs} is currently supported.
4128 @var{label} is the entry point of the function and if omitted @var{name}
4129 prepended with the @samp{leading char} is used.
4130 @samp{leading char} is usually @code{_} or nothing, depending on the target.
4131 All functions are currently defined to have @code{void} return type.
4132 The function must be terminated with @code{.endfunc}.
4135 @section @code{.global @var{symbol}}, @code{.globl @var{symbol}}
4137 @cindex @code{global} directive
4138 @cindex symbol, making visible to linker
4139 @code{.global} makes the symbol visible to @code{@value{LD}}. If you define
4140 @var{symbol} in your partial program, its value is made available to
4141 other partial programs that are linked with it. Otherwise,
4142 @var{symbol} takes its attributes from a symbol of the same name
4143 from another file linked into the same program.
4145 Both spellings (@samp{.globl} and @samp{.global}) are accepted, for
4146 compatibility with other assemblers.
4149 On the HPPA, @code{.global} is not always enough to make it accessible to other
4150 partial programs. You may need the HPPA-only @code{.EXPORT} directive as well.
4151 @xref{HPPA Directives,, HPPA Assembler Directives}.
4156 @section @code{.hidden @var{names}}
4158 @cindex @code{.hidden} directive
4160 This one of the ELF visibility directives. The other two are
4161 @code{.internal} (@pxref{Internal,,@code{.internal}}) and
4162 @code{.protected} (@pxref{Protected,,@code{.protected}}).
4164 This directive overrides the named symbols default visibility (which is set by
4165 their binding: local, global or weak). The directive sets the visibility to
4166 @code{hidden} which means that the symbols are not visible to other components.
4167 Such symbols are always considered to be @code{protected} as well.
4171 @section @code{.hword @var{expressions}}
4173 @cindex @code{hword} directive
4174 @cindex integers, 16-bit
4175 @cindex numbers, 16-bit
4176 @cindex sixteen bit integers
4177 This expects zero or more @var{expressions}, and emits
4178 a 16 bit number for each.
4181 This directive is a synonym for @samp{.short}; depending on the target
4182 architecture, it may also be a synonym for @samp{.word}.
4186 This directive is a synonym for @samp{.short}.
4189 This directive is a synonym for both @samp{.short} and @samp{.word}.
4194 @section @code{.ident}
4196 @cindex @code{ident} directive
4197 This directive is used by some assemblers to place tags in object files.
4198 @command{@value{AS}} simply accepts the directive for source-file
4199 compatibility with such assemblers, but does not actually emit anything
4203 @section @code{.if @var{absolute expression}}
4205 @cindex conditional assembly
4206 @cindex @code{if} directive
4207 @code{.if} marks the beginning of a section of code which is only
4208 considered part of the source program being assembled if the argument
4209 (which must be an @var{absolute expression}) is non-zero. The end of
4210 the conditional section of code must be marked by @code{.endif}
4211 (@pxref{Endif,,@code{.endif}}); optionally, you may include code for the
4212 alternative condition, flagged by @code{.else} (@pxref{Else,,@code{.else}}).
4213 If you have several conditions to check, @code{.elseif} may be used to avoid
4214 nesting blocks if/else within each subsequent @code{.else} block.
4216 The following variants of @code{.if} are also supported:
4218 @cindex @code{ifdef} directive
4219 @item .ifdef @var{symbol}
4220 Assembles the following section of code if the specified @var{symbol}
4223 @cindex @code{ifc} directive
4224 @item .ifc @var{string1},@var{string2}
4225 Assembles the following section of code if the two strings are the same. The
4226 strings may be optionally quoted with single quotes. If they are not quoted,
4227 the first string stops at the first comma, and the second string stops at the
4228 end of the line. Strings which contain whitespace should be quoted. The
4229 string comparison is case sensitive.
4231 @cindex @code{ifeq} directive
4232 @item .ifeq @var{absolute expression}
4233 Assembles the following section of code if the argument is zero.
4235 @cindex @code{ifeqs} directive
4236 @item .ifeqs @var{string1},@var{string2}
4237 Another form of @code{.ifc}. The strings must be quoted using double quotes.
4239 @cindex @code{ifge} directive
4240 @item .ifge @var{absolute expression}
4241 Assembles the following section of code if the argument is greater than or
4244 @cindex @code{ifgt} directive
4245 @item .ifgt @var{absolute expression}
4246 Assembles the following section of code if the argument is greater than zero.
4248 @cindex @code{ifle} directive
4249 @item .ifle @var{absolute expression}
4250 Assembles the following section of code if the argument is less than or equal
4253 @cindex @code{iflt} directive
4254 @item .iflt @var{absolute expression}
4255 Assembles the following section of code if the argument is less than zero.
4257 @cindex @code{ifnc} directive
4258 @item .ifnc @var{string1},@var{string2}.
4259 Like @code{.ifc}, but the sense of the test is reversed: this assembles the
4260 following section of code if the two strings are not the same.
4262 @cindex @code{ifndef} directive
4263 @cindex @code{ifnotdef} directive
4264 @item .ifndef @var{symbol}
4265 @itemx .ifnotdef @var{symbol}
4266 Assembles the following section of code if the specified @var{symbol}
4267 has not been defined. Both spelling variants are equivalent.
4269 @cindex @code{ifne} directive
4270 @item .ifne @var{absolute expression}
4271 Assembles the following section of code if the argument is not equal to zero
4272 (in other words, this is equivalent to @code{.if}).
4274 @cindex @code{ifnes} directive
4275 @item .ifnes @var{string1},@var{string2}
4276 Like @code{.ifeqs}, but the sense of the test is reversed: this assembles the
4277 following section of code if the two strings are not the same.
4281 @section @code{.incbin "@var{file}"[,@var{skip}[,@var{count}]]}
4283 @cindex @code{incbin} directive
4284 @cindex binary files, including
4285 The @code{incbin} directive includes @var{file} verbatim at the current
4286 location. You can control the search paths used with the @samp{-I} command-line
4287 option (@pxref{Invoking,,Command-Line Options}). Quotation marks are required
4290 The @var{skip} argument skips a number of bytes from the start of the
4291 @var{file}. The @var{count} argument indicates the maximum number of bytes to
4292 read. Note that the data is not aligned in any way, so it is the user's
4293 responsibility to make sure that proper alignment is provided both before and
4294 after the @code{incbin} directive.
4297 @section @code{.include "@var{file}"}
4299 @cindex @code{include} directive
4300 @cindex supporting files, including
4301 @cindex files, including
4302 This directive provides a way to include supporting files at specified
4303 points in your source program. The code from @var{file} is assembled as
4304 if it followed the point of the @code{.include}; when the end of the
4305 included file is reached, assembly of the original file continues. You
4306 can control the search paths used with the @samp{-I} command-line option
4307 (@pxref{Invoking,,Command-Line Options}). Quotation marks are required
4311 @section @code{.int @var{expressions}}
4313 @cindex @code{int} directive
4314 @cindex integers, 32-bit
4315 Expect zero or more @var{expressions}, of any section, separated by commas.
4316 For each expression, emit a number that, at run time, is the value of that
4317 expression. The byte order and bit size of the number depends on what kind
4318 of target the assembly is for.
4322 On the H8/500 and most forms of the H8/300, @code{.int} emits 16-bit
4323 integers. On the H8/300H and the Hitachi SH, however, @code{.int} emits
4330 @section @code{.internal @var{names}}
4332 @cindex @code{.internal} directive
4334 This one of the ELF visibility directives. The other two are
4335 @code{.hidden} (@pxref{Hidden,,@code{.hidden}}) and
4336 @code{.protected} (@pxref{Protected,,@code{.protected}}).
4338 This directive overrides the named symbols default visibility (which is set by
4339 their binding: local, global or weak). The directive sets the visibility to
4340 @code{internal} which means that the symbols are considered to be @code{hidden}
4341 (ie not visible to other components), and that some extra, processor specific
4342 processing must also be performed upon the symbols as well.
4346 @section @code{.irp @var{symbol},@var{values}}@dots{}
4348 @cindex @code{irp} directive
4349 Evaluate a sequence of statements assigning different values to @var{symbol}.
4350 The sequence of statements starts at the @code{.irp} directive, and is
4351 terminated by an @code{.endr} directive. For each @var{value}, @var{symbol} is
4352 set to @var{value}, and the sequence of statements is assembled. If no
4353 @var{value} is listed, the sequence of statements is assembled once, with
4354 @var{symbol} set to the null string. To refer to @var{symbol} within the
4355 sequence of statements, use @var{\symbol}.
4357 For example, assembling
4365 is equivalent to assembling
4374 @section @code{.irpc @var{symbol},@var{values}}@dots{}
4376 @cindex @code{irpc} directive
4377 Evaluate a sequence of statements assigning different values to @var{symbol}.
4378 The sequence of statements starts at the @code{.irpc} directive, and is
4379 terminated by an @code{.endr} directive. For each character in @var{value},
4380 @var{symbol} is set to the character, and the sequence of statements is
4381 assembled. If no @var{value} is listed, the sequence of statements is
4382 assembled once, with @var{symbol} set to the null string. To refer to
4383 @var{symbol} within the sequence of statements, use @var{\symbol}.
4385 For example, assembling
4393 is equivalent to assembling
4402 @section @code{.lcomm @var{symbol} , @var{length}}
4404 @cindex @code{lcomm} directive
4405 @cindex local common symbols
4406 @cindex symbols, local common
4407 Reserve @var{length} (an absolute expression) bytes for a local common
4408 denoted by @var{symbol}. The section and value of @var{symbol} are
4409 those of the new local common. The addresses are allocated in the bss
4410 section, so that at run-time the bytes start off zeroed. @var{Symbol}
4411 is not declared global (@pxref{Global,,@code{.global}}), so is normally
4412 not visible to @code{@value{LD}}.
4415 Some targets permit a third argument to be used with @code{.lcomm}. This
4416 argument specifies the desired alignment of the symbol in the bss section.
4420 The syntax for @code{.lcomm} differs slightly on the HPPA. The syntax is
4421 @samp{@var{symbol} .lcomm, @var{length}}; @var{symbol} is optional.
4425 @section @code{.lflags}
4427 @cindex @code{lflags} directive (ignored)
4428 @command{@value{AS}} accepts this directive, for compatibility with other
4429 assemblers, but ignores it.
4431 @ifclear no-line-dir
4433 @section @code{.line @var{line-number}}
4435 @cindex @code{line} directive
4439 @section @code{.ln @var{line-number}}
4441 @cindex @code{ln} directive
4443 @cindex logical line number
4445 Change the logical line number. @var{line-number} must be an absolute
4446 expression. The next line has that logical line number. Therefore any other
4447 statements on the current line (after a statement separator character) are
4448 reported as on logical line number @var{line-number} @minus{} 1. One day
4449 @command{@value{AS}} will no longer support this directive: it is recognized only
4450 for compatibility with existing assembler programs.
4454 @emph{Warning:} In the AMD29K configuration of @value{AS}, this command is
4455 not available; use the synonym @code{.ln} in that context.
4460 @ifclear no-line-dir
4461 Even though this is a directive associated with the @code{a.out} or
4462 @code{b.out} object-code formats, @command{@value{AS}} still recognizes it
4463 when producing COFF output, and treats @samp{.line} as though it
4464 were the COFF @samp{.ln} @emph{if} it is found outside a
4465 @code{.def}/@code{.endef} pair.
4467 Inside a @code{.def}, @samp{.line} is, instead, one of the directives
4468 used by compilers to generate auxiliary symbol information for
4473 @section @code{.linkonce [@var{type}]}
4475 @cindex @code{linkonce} directive
4476 @cindex common sections
4477 Mark the current section so that the linker only includes a single copy of it.
4478 This may be used to include the same section in several different object files,
4479 but ensure that the linker will only include it once in the final output file.
4480 The @code{.linkonce} pseudo-op must be used for each instance of the section.
4481 Duplicate sections are detected based on the section name, so it should be
4484 This directive is only supported by a few object file formats; as of this
4485 writing, the only object file format which supports it is the Portable
4486 Executable format used on Windows NT.
4488 The @var{type} argument is optional. If specified, it must be one of the
4489 following strings. For example:
4493 Not all types may be supported on all object file formats.
4497 Silently discard duplicate sections. This is the default.
4500 Warn if there are duplicate sections, but still keep only one copy.
4503 Warn if any of the duplicates have different sizes.
4506 Warn if any of the duplicates do not have exactly the same contents.
4510 @section @code{.ln @var{line-number}}
4512 @cindex @code{ln} directive
4513 @ifclear no-line-dir
4514 @samp{.ln} is a synonym for @samp{.line}.
4517 Tell @command{@value{AS}} to change the logical line number. @var{line-number}
4518 must be an absolute expression. The next line has that logical
4519 line number, so any other statements on the current line (after a
4520 statement separator character @code{;}) are reported as on logical
4521 line number @var{line-number} @minus{} 1.
4524 This directive is accepted, but ignored, when @command{@value{AS}} is
4525 configured for @code{b.out}; its effect is only associated with COFF
4531 @section @code{.mri @var{val}}
4533 @cindex @code{mri} directive
4534 @cindex MRI mode, temporarily
4535 If @var{val} is non-zero, this tells @command{@value{AS}} to enter MRI mode. If
4536 @var{val} is zero, this tells @command{@value{AS}} to exit MRI mode. This change
4537 affects code assembled until the next @code{.mri} directive, or until the end
4538 of the file. @xref{M, MRI mode, MRI mode}.
4541 @section @code{.list}
4543 @cindex @code{list} directive
4544 @cindex listing control, turning on
4545 Control (in conjunction with the @code{.nolist} directive) whether or
4546 not assembly listings are generated. These two directives maintain an
4547 internal counter (which is zero initially). @code{.list} increments the
4548 counter, and @code{.nolist} decrements it. Assembly listings are
4549 generated whenever the counter is greater than zero.
4551 By default, listings are disabled. When you enable them (with the
4552 @samp{-a} command line option; @pxref{Invoking,,Command-Line Options}),
4553 the initial value of the listing counter is one.
4556 @section @code{.long @var{expressions}}
4558 @cindex @code{long} directive
4559 @code{.long} is the same as @samp{.int}, @pxref{Int,,@code{.int}}.
4562 @c no one seems to know what this is for or whether this description is
4563 @c what it really ought to do
4565 @section @code{.lsym @var{symbol}, @var{expression}}
4567 @cindex @code{lsym} directive
4568 @cindex symbol, not referenced in assembly
4569 @code{.lsym} creates a new symbol named @var{symbol}, but does not put it in
4570 the hash table, ensuring it cannot be referenced by name during the
4571 rest of the assembly. This sets the attributes of the symbol to be
4572 the same as the expression value:
4574 @var{other} = @var{descriptor} = 0
4575 @var{type} = @r{(section of @var{expression})}
4576 @var{value} = @var{expression}
4579 The new symbol is not flagged as external.
4583 @section @code{.macro}
4586 The commands @code{.macro} and @code{.endm} allow you to define macros that
4587 generate assembly output. For example, this definition specifies a macro
4588 @code{sum} that puts a sequence of numbers into memory:
4591 .macro sum from=0, to=5
4600 With that definition, @samp{SUM 0,5} is equivalent to this assembly input:
4612 @item .macro @var{macname}
4613 @itemx .macro @var{macname} @var{macargs} @dots{}
4614 @cindex @code{macro} directive
4615 Begin the definition of a macro called @var{macname}. If your macro
4616 definition requires arguments, specify their names after the macro name,
4617 separated by commas or spaces. You can supply a default value for any
4618 macro argument by following the name with @samp{=@var{deflt}}. For
4619 example, these are all valid @code{.macro} statements:
4623 Begin the definition of a macro called @code{comm}, which takes no
4626 @item .macro plus1 p, p1
4627 @itemx .macro plus1 p p1
4628 Either statement begins the definition of a macro called @code{plus1},
4629 which takes two arguments; within the macro definition, write
4630 @samp{\p} or @samp{\p1} to evaluate the arguments.
4632 @item .macro reserve_str p1=0 p2
4633 Begin the definition of a macro called @code{reserve_str}, with two
4634 arguments. The first argument has a default value, but not the second.
4635 After the definition is complete, you can call the macro either as
4636 @samp{reserve_str @var{a},@var{b}} (with @samp{\p1} evaluating to
4637 @var{a} and @samp{\p2} evaluating to @var{b}), or as @samp{reserve_str
4638 ,@var{b}} (with @samp{\p1} evaluating as the default, in this case
4639 @samp{0}, and @samp{\p2} evaluating to @var{b}).
4642 When you call a macro, you can specify the argument values either by
4643 position, or by keyword. For example, @samp{sum 9,17} is equivalent to
4644 @samp{sum to=17, from=9}.
4647 @cindex @code{endm} directive
4648 Mark the end of a macro definition.
4651 @cindex @code{exitm} directive
4652 Exit early from the current macro definition.
4654 @cindex number of macros executed
4655 @cindex macros, count executed
4657 @command{@value{AS}} maintains a counter of how many macros it has
4658 executed in this pseudo-variable; you can copy that number to your
4659 output with @samp{\@@}, but @emph{only within a macro definition}.
4662 @item LOCAL @var{name} [ , @dots{} ]
4663 @emph{Warning: @code{LOCAL} is only available if you select ``alternate
4664 macro syntax'' with @samp{-a} or @samp{--alternate}.} @xref{Alternate,,
4665 Alternate macro syntax}.
4667 Generate a string replacement for each of the @var{name} arguments, and
4668 replace any instances of @var{name} in each macro expansion. The
4669 replacement string is unique in the assembly, and different for each
4670 separate macro expansion. @code{LOCAL} allows you to write macros that
4671 define symbols, without fear of conflict between separate macro expansions.
4676 @section @code{.nolist}
4678 @cindex @code{nolist} directive
4679 @cindex listing control, turning off
4680 Control (in conjunction with the @code{.list} directive) whether or
4681 not assembly listings are generated. These two directives maintain an
4682 internal counter (which is zero initially). @code{.list} increments the
4683 counter, and @code{.nolist} decrements it. Assembly listings are
4684 generated whenever the counter is greater than zero.
4687 @section @code{.octa @var{bignums}}
4689 @c FIXME: double size emitted for "octa" on i960, others? Or warn?
4690 @cindex @code{octa} directive
4691 @cindex integer, 16-byte
4692 @cindex sixteen byte integer
4693 This directive expects zero or more bignums, separated by commas. For each
4694 bignum, it emits a 16-byte integer.
4696 The term ``octa'' comes from contexts in which a ``word'' is two bytes;
4697 hence @emph{octa}-word for 16 bytes.
4700 @section @code{.org @var{new-lc} , @var{fill}}
4702 @cindex @code{org} directive
4703 @cindex location counter, advancing
4704 @cindex advancing location counter
4705 @cindex current address, advancing
4706 Advance the location counter of the current section to
4707 @var{new-lc}. @var{new-lc} is either an absolute expression or an
4708 expression with the same section as the current subsection. That is,
4709 you can't use @code{.org} to cross sections: if @var{new-lc} has the
4710 wrong section, the @code{.org} directive is ignored. To be compatible
4711 with former assemblers, if the section of @var{new-lc} is absolute,
4712 @command{@value{AS}} issues a warning, then pretends the section of @var{new-lc}
4713 is the same as the current subsection.
4715 @code{.org} may only increase the location counter, or leave it
4716 unchanged; you cannot use @code{.org} to move the location counter
4719 @c double negative used below "not undefined" because this is a specific
4720 @c reference to "undefined" (as SEG_UNKNOWN is called in this manual)
4721 @c section. doc@cygnus.com 18feb91
4722 Because @command{@value{AS}} tries to assemble programs in one pass, @var{new-lc}
4723 may not be undefined. If you really detest this restriction we eagerly await
4724 a chance to share your improved assembler.
4726 Beware that the origin is relative to the start of the section, not
4727 to the start of the subsection. This is compatible with other
4728 people's assemblers.
4730 When the location counter (of the current subsection) is advanced, the
4731 intervening bytes are filled with @var{fill} which should be an
4732 absolute expression. If the comma and @var{fill} are omitted,
4733 @var{fill} defaults to zero.
4736 @section @code{.p2align[wl] @var{abs-expr}, @var{abs-expr}, @var{abs-expr}}
4738 @cindex padding the location counter given a power of two
4739 @cindex @code{p2align} directive
4740 Pad the location counter (in the current subsection) to a particular
4741 storage boundary. The first expression (which must be absolute) is the
4742 number of low-order zero bits the location counter must have after
4743 advancement. For example @samp{.p2align 3} advances the location
4744 counter until it a multiple of 8. If the location counter is already a
4745 multiple of 8, no change is needed.
4747 The second expression (also absolute) gives the fill value to be stored in the
4748 padding bytes. It (and the comma) may be omitted. If it is omitted, the
4749 padding bytes are normally zero. However, on some systems, if the section is
4750 marked as containing code and the fill value is omitted, the space is filled
4751 with no-op instructions.
4753 The third expression is also absolute, and is also optional. If it is present,
4754 it is the maximum number of bytes that should be skipped by this alignment
4755 directive. If doing the alignment would require skipping more bytes than the
4756 specified maximum, then the alignment is not done at all. You can omit the
4757 fill value (the second argument) entirely by simply using two commas after the
4758 required alignment; this can be useful if you want the alignment to be filled
4759 with no-op instructions when appropriate.
4761 @cindex @code{p2alignw} directive
4762 @cindex @code{p2alignl} directive
4763 The @code{.p2alignw} and @code{.p2alignl} directives are variants of the
4764 @code{.p2align} directive. The @code{.p2alignw} directive treats the fill
4765 pattern as a two byte word value. The @code{.p2alignl} directives treats the
4766 fill pattern as a four byte longword value. For example, @code{.p2alignw
4767 2,0x368d} will align to a multiple of 4. If it skips two bytes, they will be
4768 filled in with the value 0x368d (the exact placement of the bytes depends upon
4769 the endianness of the processor). If it skips 1 or 3 bytes, the fill value is
4774 @section @code{.previous}
4776 @cindex @code{.previous} directive
4777 @cindex Section Stack
4778 This is one of the ELF section stack manipulation directives. The others are
4779 @code{.section} (@pxref{Section}), @code{.subsection} (@pxref{SubSection}),
4780 @code{.pushsection} (@pxref{PushSection}), and @code{.popsection}
4781 (@pxref{PopSection}).
4783 This directive swaps the current section (and subsection) with most recently
4784 referenced section (and subsection) prior to this one. Multiple
4785 @code{.previous} directives in a row will flip between two sections (and their
4788 In terms of the section stack, this directive swaps the current section with
4789 the top section on the section stack.
4794 @section @code{.popsection}
4796 @cindex @code{.popsection} directive
4797 @cindex Section Stack
4798 This is one of the ELF section stack manipulation directives. The others are
4799 @code{.section} (@pxref{Section}), @code{.subsection} (@pxref{SubSection}),
4800 @code{.pushsection} (@pxref{PushSection}), and @code{.previous}
4803 This directive replaces the current section (and subsection) with the top
4804 section (and subsection) on the section stack. This section is popped off the
4809 @section @code{.print @var{string}}
4811 @cindex @code{print} directive
4812 @command{@value{AS}} will print @var{string} on the standard output during
4813 assembly. You must put @var{string} in double quotes.
4817 @section @code{.protected @var{names}}
4819 @cindex @code{.protected} directive
4821 This one of the ELF visibility directives. The other two are
4822 @code{.hidden} (@pxref{Hidden}) and @code{.internal} (@pxref{Internal}).
4824 This directive overrides the named symbols default visibility (which is set by
4825 their binding: local, global or weak). The directive sets the visibility to
4826 @code{protected} which means that any references to the symbols from within the
4827 components that defines them must be resolved to the definition in that
4828 component, even if a definition in another component would normally preempt
4833 @section @code{.psize @var{lines} , @var{columns}}
4835 @cindex @code{psize} directive
4836 @cindex listing control: paper size
4837 @cindex paper size, for listings
4838 Use this directive to declare the number of lines---and, optionally, the
4839 number of columns---to use for each page, when generating listings.
4841 If you do not use @code{.psize}, listings use a default line-count
4842 of 60. You may omit the comma and @var{columns} specification; the
4843 default width is 200 columns.
4845 @command{@value{AS}} generates formfeeds whenever the specified number of
4846 lines is exceeded (or whenever you explicitly request one, using
4849 If you specify @var{lines} as @code{0}, no formfeeds are generated save
4850 those explicitly specified with @code{.eject}.
4853 @section @code{.purgem @var{name}}
4855 @cindex @code{purgem} directive
4856 Undefine the macro @var{name}, so that later uses of the string will not be
4857 expanded. @xref{Macro}.
4861 @section @code{.pushsection @var{name} , @var{subsection}}
4863 @cindex @code{.pushsection} directive
4864 @cindex Section Stack
4865 This is one of the ELF section stack manipulation directives. The others are
4866 @code{.section} (@pxref{Section}), @code{.subsection} (@pxref{SubSection}),
4867 @code{.popsection} (@pxref{PopSection}), and @code{.previous}
4870 This directive is a synonym for @code{.section}. It pushes the current section
4871 (and subsection) onto the top of the section stack, and then replaces the
4872 current section and subsection with @code{name} and @code{subsection}.
4876 @section @code{.quad @var{bignums}}
4878 @cindex @code{quad} directive
4879 @code{.quad} expects zero or more bignums, separated by commas. For
4880 each bignum, it emits
4882 an 8-byte integer. If the bignum won't fit in 8 bytes, it prints a
4883 warning message; and just takes the lowest order 8 bytes of the bignum.
4884 @cindex eight-byte integer
4885 @cindex integer, 8-byte
4887 The term ``quad'' comes from contexts in which a ``word'' is two bytes;
4888 hence @emph{quad}-word for 8 bytes.
4891 a 16-byte integer. If the bignum won't fit in 16 bytes, it prints a
4892 warning message; and just takes the lowest order 16 bytes of the bignum.
4893 @cindex sixteen-byte integer
4894 @cindex integer, 16-byte
4898 @section @code{.rept @var{count}}
4900 @cindex @code{rept} directive
4901 Repeat the sequence of lines between the @code{.rept} directive and the next
4902 @code{.endr} directive @var{count} times.
4904 For example, assembling
4912 is equivalent to assembling
4921 @section @code{.sbttl "@var{subheading}"}
4923 @cindex @code{sbttl} directive
4924 @cindex subtitles for listings
4925 @cindex listing control: subtitle
4926 Use @var{subheading} as the title (third line, immediately after the
4927 title line) when generating assembly listings.
4929 This directive affects subsequent pages, as well as the current page if
4930 it appears within ten lines of the top of a page.
4934 @section @code{.scl @var{class}}
4936 @cindex @code{scl} directive
4937 @cindex symbol storage class (COFF)
4938 @cindex COFF symbol storage class
4939 Set the storage-class value for a symbol. This directive may only be
4940 used inside a @code{.def}/@code{.endef} pair. Storage class may flag
4941 whether a symbol is static or external, or it may record further
4942 symbolic debugging information.
4945 The @samp{.scl} directive is primarily associated with COFF output; when
4946 configured to generate @code{b.out} output format, @command{@value{AS}}
4947 accepts this directive but ignores it.
4952 @section @code{.section @var{name}} (COFF version)
4954 @cindex @code{section} directive
4955 @cindex named section
4956 Use the @code{.section} directive to assemble the following code into a section
4959 This directive is only supported for targets that actually support arbitrarily
4960 named sections; on @code{a.out} targets, for example, it is not accepted, even
4961 with a standard @code{a.out} section name.
4963 For COFF targets, the @code{.section} directive is used in one of the following
4967 .section @var{name}[, "@var{flags}"]
4968 .section @var{name}[, @var{subsegment}]
4971 If the optional argument is quoted, it is taken as flags to use for the
4972 section. Each flag is a single character. The following flags are recognized:
4975 bss section (uninitialized data)
4977 section is not loaded
4987 shared section (meaningful for PE targets)
4989 ignored. (For compatibility with the ELF version)
4992 If no flags are specified, the default flags depend upon the section name. If
4993 the section name is not recognized, the default will be for the section to be
4994 loaded and writable. Note the @code{n} and @code{w} flags remove attributes
4995 from the section, rather than adding them, so if they are used on their own it
4996 will be as if no flags had been specified at all.
4998 If the optional argument to the @code{.section} directive is not quoted, it is
4999 taken as a subsegment number (@pxref{Sub-Sections}).
5002 @section @code{.section @var{name}} (ELF version)
5004 @cindex @code{section} directive
5005 @cindex named section
5007 @cindex Section Stack
5008 This is one of the ELF section stack manipulation directives. The others are
5009 @code{.subsection} (@pxref{SubSection}), @code{.pushsection}
5010 (@pxref{PushSection}), @code{.popsection} (@pxref{PopSection}), and
5011 @code{.previous} (@pxref{Previous}).
5014 For ELF targets, the @code{.section} directive is used like this:
5017 .section @var{name} [, "@var{flags}"[, @@@var{type}[, @@@var{entsize}]]]
5020 The optional @var{flags} argument is a quoted string which may contain any
5021 combination of the following characters:
5024 section is allocatable
5028 section is executable
5030 section is mergeable
5032 section contains zero terminated strings
5035 The optional @var{type} argument may contain one of the following constants:
5038 section contains data
5040 section does not contain data (i.e., section only occupies space)
5043 If @var{flags} contains @code{M} flag, @var{type} argument must be specified
5044 as well as @var{entsize} argument. Sections with @code{M} flag but not
5045 @code{S} flag must contain fixed size constants, each @var{entsize} octets
5046 long. Sections with both @code{M} and @code{S} must contain zero terminated
5047 strings where each character is @var{entsize} bytes long. The linker may remove
5048 duplicates within sections with the same name, same entity size and same flags.
5050 If no flags are specified, the default flags depend upon the section name. If
5051 the section name is not recognized, the default will be for the section to have
5052 none of the above flags: it will not be allocated in memory, nor writable, nor
5053 executable. The section will contain data.
5055 For ELF targets, the assembler supports another type of @code{.section}
5056 directive for compatibility with the Solaris assembler:
5059 .section "@var{name}"[, @var{flags}...]
5062 Note that the section name is quoted. There may be a sequence of comma
5066 section is allocatable
5070 section is executable
5073 This directive replaces the current section and subsection. The replaced
5074 section and subsection are pushed onto the section stack. See the contents of
5075 the gas testsuite directory @code{gas/testsuite/gas/elf} for some examples of
5076 how this directive and the other section stack directives work.
5079 @section @code{.set @var{symbol}, @var{expression}}
5081 @cindex @code{set} directive
5082 @cindex symbol value, setting
5083 Set the value of @var{symbol} to @var{expression}. This
5084 changes @var{symbol}'s value and type to conform to
5085 @var{expression}. If @var{symbol} was flagged as external, it remains
5086 flagged (@pxref{Symbol Attributes}).
5088 You may @code{.set} a symbol many times in the same assembly.
5090 If you @code{.set} a global symbol, the value stored in the object
5091 file is the last value stored into it.
5094 The syntax for @code{set} on the HPPA is
5095 @samp{@var{symbol} .set @var{expression}}.
5099 @section @code{.short @var{expressions}}
5101 @cindex @code{short} directive
5103 @code{.short} is normally the same as @samp{.word}.
5104 @xref{Word,,@code{.word}}.
5106 In some configurations, however, @code{.short} and @code{.word} generate
5107 numbers of different lengths; @pxref{Machine Dependencies}.
5111 @code{.short} is the same as @samp{.word}. @xref{Word,,@code{.word}}.
5114 This expects zero or more @var{expressions}, and emits
5115 a 16 bit number for each.
5120 @section @code{.single @var{flonums}}
5122 @cindex @code{single} directive
5123 @cindex floating point numbers (single)
5124 This directive assembles zero or more flonums, separated by commas. It
5125 has the same effect as @code{.float}.
5127 The exact kind of floating point numbers emitted depends on how
5128 @command{@value{AS}} is configured. @xref{Machine Dependencies}.
5132 On the @value{TARGET} family, @code{.single} emits 32-bit floating point
5133 numbers in @sc{ieee} format.
5138 @section @code{.size} (COFF version)
5140 @cindex @code{size} directive
5141 This directive is generated by compilers to include auxiliary debugging
5142 information in the symbol table. It is only permitted inside
5143 @code{.def}/@code{.endef} pairs.
5146 @samp{.size} is only meaningful when generating COFF format output; when
5147 @command{@value{AS}} is generating @code{b.out}, it accepts this directive but
5151 @section @code{.size @var{name} , @var{expression}} (ELF version)
5152 @cindex @code{size} directive
5154 This directive is used to set the size associated with a symbol @var{name}.
5155 The size in bytes is computed from @var{expression} which can make use of label
5156 arithmetic. This directive is typically used to set the size of function
5160 @section @code{.sleb128 @var{expressions}}
5162 @cindex @code{sleb128} directive
5163 @var{sleb128} stands for ``signed little endian base 128.'' This is a
5164 compact, variable length representation of numbers used by the DWARF
5165 symbolic debugging format. @xref{Uleb128,@code{.uleb128}}.
5167 @ifclear no-space-dir
5169 @section @code{.skip @var{size} , @var{fill}}
5171 @cindex @code{skip} directive
5172 @cindex filling memory
5173 This directive emits @var{size} bytes, each of value @var{fill}. Both
5174 @var{size} and @var{fill} are absolute expressions. If the comma and
5175 @var{fill} are omitted, @var{fill} is assumed to be zero. This is the same as
5179 @section @code{.space @var{size} , @var{fill}}
5181 @cindex @code{space} directive
5182 @cindex filling memory
5183 This directive emits @var{size} bytes, each of value @var{fill}. Both
5184 @var{size} and @var{fill} are absolute expressions. If the comma
5185 and @var{fill} are omitted, @var{fill} is assumed to be zero. This is the same
5190 @emph{Warning:} @code{.space} has a completely different meaning for HPPA
5191 targets; use @code{.block} as a substitute. See @cite{HP9000 Series 800
5192 Assembly Language Reference Manual} (HP 92432-90001) for the meaning of the
5193 @code{.space} directive. @xref{HPPA Directives,,HPPA Assembler Directives},
5202 @section @code{.space}
5203 @cindex @code{space} directive
5205 On the AMD 29K, this directive is ignored; it is accepted for
5206 compatibility with other AMD 29K assemblers.
5209 @emph{Warning:} In most versions of the @sc{gnu} assembler, the directive
5210 @code{.space} has the effect of @code{.block} @xref{Machine Dependencies}.
5216 @section @code{.stabd, .stabn, .stabs}
5218 @cindex symbolic debuggers, information for
5219 @cindex @code{stab@var{x}} directives
5220 There are three directives that begin @samp{.stab}.
5221 All emit symbols (@pxref{Symbols}), for use by symbolic debuggers.
5222 The symbols are not entered in the @command{@value{AS}} hash table: they
5223 cannot be referenced elsewhere in the source file.
5224 Up to five fields are required:
5228 This is the symbol's name. It may contain any character except
5229 @samp{\000}, so is more general than ordinary symbol names. Some
5230 debuggers used to code arbitrarily complex structures into symbol names
5234 An absolute expression. The symbol's type is set to the low 8 bits of
5235 this expression. Any bit pattern is permitted, but @code{@value{LD}}
5236 and debuggers choke on silly bit patterns.
5239 An absolute expression. The symbol's ``other'' attribute is set to the
5240 low 8 bits of this expression.
5243 An absolute expression. The symbol's descriptor is set to the low 16
5244 bits of this expression.
5247 An absolute expression which becomes the symbol's value.
5250 If a warning is detected while reading a @code{.stabd}, @code{.stabn},
5251 or @code{.stabs} statement, the symbol has probably already been created;
5252 you get a half-formed symbol in your object file. This is
5253 compatible with earlier assemblers!
5256 @cindex @code{stabd} directive
5257 @item .stabd @var{type} , @var{other} , @var{desc}
5259 The ``name'' of the symbol generated is not even an empty string.
5260 It is a null pointer, for compatibility. Older assemblers used a
5261 null pointer so they didn't waste space in object files with empty
5264 The symbol's value is set to the location counter,
5265 relocatably. When your program is linked, the value of this symbol
5266 is the address of the location counter when the @code{.stabd} was
5269 @cindex @code{stabn} directive
5270 @item .stabn @var{type} , @var{other} , @var{desc} , @var{value}
5271 The name of the symbol is set to the empty string @code{""}.
5273 @cindex @code{stabs} directive
5274 @item .stabs @var{string} , @var{type} , @var{other} , @var{desc} , @var{value}
5275 All five fields are specified.
5281 @section @code{.string} "@var{str}"
5283 @cindex string, copying to object file
5284 @cindex @code{string} directive
5286 Copy the characters in @var{str} to the object file. You may specify more than
5287 one string to copy, separated by commas. Unless otherwise specified for a
5288 particular machine, the assembler marks the end of each string with a 0 byte.
5289 You can use any of the escape sequences described in @ref{Strings,,Strings}.
5292 @section @code{.struct @var{expression}}
5294 @cindex @code{struct} directive
5295 Switch to the absolute section, and set the section offset to @var{expression},
5296 which must be an absolute expression. You might use this as follows:
5305 This would define the symbol @code{field1} to have the value 0, the symbol
5306 @code{field2} to have the value 4, and the symbol @code{field3} to have the
5307 value 8. Assembly would be left in the absolute section, and you would need to
5308 use a @code{.section} directive of some sort to change to some other section
5309 before further assembly.
5313 @section @code{.subsection @var{name}}
5315 @cindex @code{.subsection} directive
5316 @cindex Section Stack
5317 This is one of the ELF section stack manipulation directives. The others are
5318 @code{.section} (@pxref{Section}), @code{.pushsection} (@pxref{PushSection}),
5319 @code{.popsection} (@pxref{PopSection}), and @code{.previous}
5322 This directive replaces the current subsection with @code{name}. The current
5323 section is not changed. The replaced subsection is put onto the section stack
5324 in place of the then current top of stack subsection.
5329 @section @code{.symver}
5330 @cindex @code{symver} directive
5331 @cindex symbol versioning
5332 @cindex versions of symbols
5333 Use the @code{.symver} directive to bind symbols to specific version nodes
5334 within a source file. This is only supported on ELF platforms, and is
5335 typically used when assembling files to be linked into a shared library.
5336 There are cases where it may make sense to use this in objects to be bound
5337 into an application itself so as to override a versioned symbol from a
5340 For ELF targets, the @code{.symver} directive can be used like this:
5342 .symver @var{name}, @var{name2@@nodename}
5344 If the symbol @var{name} is defined within the file
5345 being assembled, the @code{.symver} directive effectively creates a symbol
5346 alias with the name @var{name2@@nodename}, and in fact the main reason that we
5347 just don't try and create a regular alias is that the @var{@@} character isn't
5348 permitted in symbol names. The @var{name2} part of the name is the actual name
5349 of the symbol by which it will be externally referenced. The name @var{name}
5350 itself is merely a name of convenience that is used so that it is possible to
5351 have definitions for multiple versions of a function within a single source
5352 file, and so that the compiler can unambiguously know which version of a
5353 function is being mentioned. The @var{nodename} portion of the alias should be
5354 the name of a node specified in the version script supplied to the linker when
5355 building a shared library. If you are attempting to override a versioned
5356 symbol from a shared library, then @var{nodename} should correspond to the
5357 nodename of the symbol you are trying to override.
5359 If the symbol @var{name} is not defined within the file being assembled, all
5360 references to @var{name} will be changed to @var{name2@@nodename}. If no
5361 reference to @var{name} is made, @var{name2@@nodename} will be removed from the
5364 Another usage of the @code{.symver} directive is:
5366 .symver @var{name}, @var{name2@@@@nodename}
5368 In this case, the symbol @var{name} must exist and be defined within
5369 the file being assembled. It is similar to @var{name2@@nodename}. The
5370 difference is @var{name2@@@@nodename} will also be used to resolve
5371 references to @var{name2} by the linker.
5373 The third usage of the @code{.symver} directive is:
5375 .symver @var{name}, @var{name2@@@@@@nodename}
5377 When @var{name} is not defined within the
5378 file being assembled, it is treated as @var{name2@@nodename}. When
5379 @var{name} is defined within the file being assembled, the symbol
5380 name, @var{name}, will be changed to @var{name2@@@@nodename}.
5385 @section @code{.tag @var{structname}}
5387 @cindex COFF structure debugging
5388 @cindex structure debugging, COFF
5389 @cindex @code{tag} directive
5390 This directive is generated by compilers to include auxiliary debugging
5391 information in the symbol table. It is only permitted inside
5392 @code{.def}/@code{.endef} pairs. Tags are used to link structure
5393 definitions in the symbol table with instances of those structures.
5396 @samp{.tag} is only used when generating COFF format output; when
5397 @command{@value{AS}} is generating @code{b.out}, it accepts this directive but
5403 @section @code{.text @var{subsection}}
5405 @cindex @code{text} directive
5406 Tells @command{@value{AS}} to assemble the following statements onto the end of
5407 the text subsection numbered @var{subsection}, which is an absolute
5408 expression. If @var{subsection} is omitted, subsection number zero
5412 @section @code{.title "@var{heading}"}
5414 @cindex @code{title} directive
5415 @cindex listing control: title line
5416 Use @var{heading} as the title (second line, immediately after the
5417 source file name and pagenumber) when generating assembly listings.
5419 This directive affects subsequent pages, as well as the current page if
5420 it appears within ten lines of the top of a page.
5423 @section @code{.type @var{int}} (COFF version)
5425 @cindex COFF symbol type
5426 @cindex symbol type, COFF
5427 @cindex @code{type} directive
5428 This directive, permitted only within @code{.def}/@code{.endef} pairs,
5429 records the integer @var{int} as the type attribute of a symbol table entry.
5432 @samp{.type} is associated only with COFF format output; when
5433 @command{@value{AS}} is configured for @code{b.out} output, it accepts this
5434 directive but ignores it.
5437 @section @code{.type @var{name} , @var{type description}} (ELF version)
5439 @cindex ELF symbol type
5440 @cindex symbol type, ELF
5441 @cindex @code{type} directive
5442 This directive is used to set the type of symbol @var{name} to be either a
5443 function symbol or an object symbol. There are five different syntaxes
5444 supported for the @var{type description} field, in order to provide
5445 compatibility with various other assemblers. The syntaxes supported are:
5448 .type <name>,#function
5449 .type <name>,#object
5451 .type <name>,@@function
5452 .type <name>,@@object
5454 .type <name>,%function
5455 .type <name>,%object
5457 .type <name>,"function"
5458 .type <name>,"object"
5460 .type <name> STT_FUNCTION
5461 .type <name> STT_OBJECT
5465 @section @code{.uleb128 @var{expressions}}
5467 @cindex @code{uleb128} directive
5468 @var{uleb128} stands for ``unsigned little endian base 128.'' This is a
5469 compact, variable length representation of numbers used by the DWARF
5470 symbolic debugging format. @xref{Sleb128,@code{.sleb128}}.
5474 @section @code{.val @var{addr}}
5476 @cindex @code{val} directive
5477 @cindex COFF value attribute
5478 @cindex value attribute, COFF
5479 This directive, permitted only within @code{.def}/@code{.endef} pairs,
5480 records the address @var{addr} as the value attribute of a symbol table
5484 @samp{.val} is used only for COFF output; when @command{@value{AS}} is
5485 configured for @code{b.out}, it accepts this directive but ignores it.
5491 @section @code{.version "@var{string}"}
5493 @cindex @code{.version}
5494 This directive creates a @code{.note} section and places into it an ELF
5495 formatted note of type NT_VERSION. The note's name is set to @code{string}.
5500 @section @code{.vtable_entry @var{table}, @var{offset}}
5502 @cindex @code{.vtable_entry}
5503 This directive finds or creates a symbol @code{table} and creates a
5504 @code{VTABLE_ENTRY} relocation for it with an addend of @code{offset}.
5507 @section @code{.vtable_inherit @var{child}, @var{parent}}
5509 @cindex @code{.vtable_inherit}
5510 This directive finds the symbol @code{child} and finds or creates the symbol
5511 @code{parent} and then creates a @code{VTABLE_INHERIT} relocation for the
5512 parent whose addend is the value of the child symbol. As a special case the
5513 parent name of @code{0} is treated as refering the @code{*ABS*} section.
5518 @section @code{.weak @var{names}}
5520 @cindex @code{.weak}
5521 This directive sets the weak attribute on the comma separated list of symbol
5522 @code{names}. If the symbols do not already exist, they will be created.
5526 @section @code{.word @var{expressions}}
5528 @cindex @code{word} directive
5529 This directive expects zero or more @var{expressions}, of any section,
5530 separated by commas.
5533 For each expression, @command{@value{AS}} emits a 32-bit number.
5536 For each expression, @command{@value{AS}} emits a 16-bit number.
5541 The size of the number emitted, and its byte order,
5542 depend on what target computer the assembly is for.
5545 @c on amd29k, i960, sparc the "special treatment to support compilers" doesn't
5546 @c happen---32-bit addressability, period; no long/short jumps.
5547 @ifset DIFF-TBL-KLUGE
5548 @cindex difference tables altered
5549 @cindex altered difference tables
5551 @emph{Warning: Special Treatment to support Compilers}
5555 Machines with a 32-bit address space, but that do less than 32-bit
5556 addressing, require the following special treatment. If the machine of
5557 interest to you does 32-bit addressing (or doesn't require it;
5558 @pxref{Machine Dependencies}), you can ignore this issue.
5561 In order to assemble compiler output into something that works,
5562 @command{@value{AS}} occasionally does strange things to @samp{.word} directives.
5563 Directives of the form @samp{.word sym1-sym2} are often emitted by
5564 compilers as part of jump tables. Therefore, when @command{@value{AS}} assembles a
5565 directive of the form @samp{.word sym1-sym2}, and the difference between
5566 @code{sym1} and @code{sym2} does not fit in 16 bits, @command{@value{AS}}
5567 creates a @dfn{secondary jump table}, immediately before the next label.
5568 This secondary jump table is preceded by a short-jump to the
5569 first byte after the secondary table. This short-jump prevents the flow
5570 of control from accidentally falling into the new table. Inside the
5571 table is a long-jump to @code{sym2}. The original @samp{.word}
5572 contains @code{sym1} minus the address of the long-jump to
5575 If there were several occurrences of @samp{.word sym1-sym2} before the
5576 secondary jump table, all of them are adjusted. If there was a
5577 @samp{.word sym3-sym4}, that also did not fit in sixteen bits, a
5578 long-jump to @code{sym4} is included in the secondary jump table,
5579 and the @code{.word} directives are adjusted to contain @code{sym3}
5580 minus the address of the long-jump to @code{sym4}; and so on, for as many
5581 entries in the original jump table as necessary.
5584 @emph{This feature may be disabled by compiling @command{@value{AS}} with the
5585 @samp{-DWORKING_DOT_WORD} option.} This feature is likely to confuse
5586 assembly language programmers.
5589 @c end DIFF-TBL-KLUGE
5592 @section Deprecated Directives
5594 @cindex deprecated directives
5595 @cindex obsolescent directives
5596 One day these directives won't work.
5597 They are included for compatibility with older assemblers.
5604 @node Machine Dependencies
5605 @chapter Machine Dependent Features
5607 @cindex machine dependencies
5608 The machine instruction sets are (almost by definition) different on
5609 each machine where @command{@value{AS}} runs. Floating point representations
5610 vary as well, and @command{@value{AS}} often supports a few additional
5611 directives or command-line options for compatibility with other
5612 assemblers on a particular platform. Finally, some versions of
5613 @command{@value{AS}} support special pseudo-instructions for branch
5616 This chapter discusses most of these differences, though it does not
5617 include details on any machine's instruction set. For details on that
5618 subject, see the hardware manufacturer's manual.
5622 * AMD29K-Dependent:: AMD 29K Dependent Features
5625 * Alpha-Dependent:: Alpha Dependent Features
5628 * ARC-Dependent:: ARC Dependent Features
5631 * ARM-Dependent:: ARM Dependent Features
5634 * CRIS-Dependent:: CRIS Dependent Features
5637 * D10V-Dependent:: D10V Dependent Features
5640 * D30V-Dependent:: D30V Dependent Features
5643 * H8/300-Dependent:: Hitachi H8/300 Dependent Features
5646 * H8/500-Dependent:: Hitachi H8/500 Dependent Features
5649 * HPPA-Dependent:: HPPA Dependent Features
5652 * ESA/390-Dependent:: IBM ESA/390 Dependent Features
5655 * i386-Dependent:: Intel 80386 and AMD x86-64 Dependent Features
5658 * i860-Dependent:: Intel 80860 Dependent Features
5661 * i960-Dependent:: Intel 80960 Dependent Features
5664 * M32R-Dependent:: M32R Dependent Features
5667 * M68K-Dependent:: M680x0 Dependent Features
5670 * M68HC11-Dependent:: M68HC11 and 68HC12 Dependent Features
5673 * M88K-Dependent:: M880x0 Dependent Features
5676 * MIPS-Dependent:: MIPS Dependent Features
5679 * MMIX-Dependent:: MMIX Dependent Features
5682 * SH-Dependent:: Hitachi SH Dependent Features
5683 * SH64-Dependent:: Hitachi SH64 Dependent Features
5686 * PDP-11-Dependent:: PDP-11 Dependent Features
5689 * PJ-Dependent:: picoJava Dependent Features
5692 * PPC-Dependent:: PowerPC Dependent Features
5695 * Sparc-Dependent:: SPARC Dependent Features
5698 * TIC54X-Dependent:: TI TMS320C54x Dependent Features
5701 * V850-Dependent:: V850 Dependent Features
5704 * Z8000-Dependent:: Z8000 Dependent Features
5707 * Vax-Dependent:: VAX Dependent Features
5714 @c The following major nodes are *sections* in the GENERIC version, *chapters*
5715 @c in single-cpu versions. This is mainly achieved by @lowersections. There is a
5716 @c peculiarity: to preserve cross-references, there must be a node called
5717 @c "Machine Dependencies". Hence the conditional nodenames in each
5718 @c major node below. Node defaulting in makeinfo requires adjacency of
5719 @c node and sectioning commands; hence the repetition of @chapter BLAH
5720 @c in both conditional blocks.
5723 @include c-a29k.texi
5727 @include c-alpha.texi
5739 @include c-cris.texi
5744 @node Machine Dependencies
5745 @chapter Machine Dependent Features
5747 The machine instruction sets are different on each Hitachi chip family,
5748 and there are also some syntax differences among the families. This
5749 chapter describes the specific @command{@value{AS}} features for each
5753 * H8/300-Dependent:: Hitachi H8/300 Dependent Features
5754 * H8/500-Dependent:: Hitachi H8/500 Dependent Features
5755 * SH-Dependent:: Hitachi SH Dependent Features
5762 @include c-d10v.texi
5766 @include c-d30v.texi
5770 @include c-h8300.texi
5774 @include c-h8500.texi
5778 @include c-hppa.texi
5782 @include c-i370.texi
5786 @include c-i386.texi
5790 @include c-i860.texi
5794 @include c-i960.texi
5798 @include c-ia64.texi
5802 @include c-m32r.texi
5806 @include c-m68k.texi
5810 @include c-m68hc11.texi
5814 @include c-m88k.texi
5818 @include c-mips.texi
5822 @include c-mmix.texi
5826 @include c-ns32k.texi
5830 @include c-pdp11.texi
5843 @include c-sh64.texi
5847 @include c-sparc.texi
5851 @include c-tic54x.texi
5863 @include c-v850.texi
5867 @c reverse effect of @down at top of generic Machine-Dep chapter
5871 @node Reporting Bugs
5872 @chapter Reporting Bugs
5873 @cindex bugs in assembler
5874 @cindex reporting bugs in assembler
5876 Your bug reports play an essential role in making @command{@value{AS}} reliable.
5878 Reporting a bug may help you by bringing a solution to your problem, or it may
5879 not. But in any case the principal function of a bug report is to help the
5880 entire community by making the next version of @command{@value{AS}} work better.
5881 Bug reports are your contribution to the maintenance of @command{@value{AS}}.
5883 In order for a bug report to serve its purpose, you must include the
5884 information that enables us to fix the bug.
5887 * Bug Criteria:: Have you found a bug?
5888 * Bug Reporting:: How to report bugs
5892 @section Have you found a bug?
5893 @cindex bug criteria
5895 If you are not sure whether you have found a bug, here are some guidelines:
5898 @cindex fatal signal
5899 @cindex assembler crash
5900 @cindex crash of assembler
5902 If the assembler gets a fatal signal, for any input whatever, that is a
5903 @command{@value{AS}} bug. Reliable assemblers never crash.
5905 @cindex error on valid input
5907 If @command{@value{AS}} produces an error message for valid input, that is a bug.
5909 @cindex invalid input
5911 If @command{@value{AS}} does not produce an error message for invalid input, that
5912 is a bug. However, you should note that your idea of ``invalid input'' might
5913 be our idea of ``an extension'' or ``support for traditional practice''.
5916 If you are an experienced user of assemblers, your suggestions for improvement
5917 of @command{@value{AS}} are welcome in any case.
5921 @section How to report bugs
5923 @cindex assembler bugs, reporting
5925 A number of companies and individuals offer support for @sc{gnu} products. If
5926 you obtained @command{@value{AS}} from a support organization, we recommend you
5927 contact that organization first.
5929 You can find contact information for many support companies and
5930 individuals in the file @file{etc/SERVICE} in the @sc{gnu} Emacs
5933 In any event, we also recommend that you send bug reports for @command{@value{AS}}
5934 to @samp{bug-binutils@@gnu.org}.
5936 The fundamental principle of reporting bugs usefully is this:
5937 @strong{report all the facts}. If you are not sure whether to state a
5938 fact or leave it out, state it!
5940 Often people omit facts because they think they know what causes the problem
5941 and assume that some details do not matter. Thus, you might assume that the
5942 name of a symbol you use in an example does not matter. Well, probably it does
5943 not, but one cannot be sure. Perhaps the bug is a stray memory reference which
5944 happens to fetch from the location where that name is stored in memory;
5945 perhaps, if the name were different, the contents of that location would fool
5946 the assembler into doing the right thing despite the bug. Play it safe and
5947 give a specific, complete example. That is the easiest thing for you to do,
5948 and the most helpful.
5950 Keep in mind that the purpose of a bug report is to enable us to fix the bug if
5951 it is new to us. Therefore, always write your bug reports on the assumption
5952 that the bug has not been reported previously.
5954 Sometimes people give a few sketchy facts and ask, ``Does this ring a
5955 bell?'' Those bug reports are useless, and we urge everyone to
5956 @emph{refuse to respond to them} except to chide the sender to report
5959 To enable us to fix the bug, you should include all these things:
5963 The version of @command{@value{AS}}. @command{@value{AS}} announces it if you start
5964 it with the @samp{--version} argument.
5966 Without this, we will not know whether there is any point in looking for
5967 the bug in the current version of @command{@value{AS}}.
5970 Any patches you may have applied to the @command{@value{AS}} source.
5973 The type of machine you are using, and the operating system name and
5977 What compiler (and its version) was used to compile @command{@value{AS}}---e.g.
5981 The command arguments you gave the assembler to assemble your example and
5982 observe the bug. To guarantee you will not omit something important, list them
5983 all. A copy of the Makefile (or the output from make) is sufficient.
5985 If we were to try to guess the arguments, we would probably guess wrong
5986 and then we might not encounter the bug.
5989 A complete input file that will reproduce the bug. If the bug is observed when
5990 the assembler is invoked via a compiler, send the assembler source, not the
5991 high level language source. Most compilers will produce the assembler source
5992 when run with the @samp{-S} option. If you are using @code{@value{GCC}}, use
5993 the options @samp{-v --save-temps}; this will save the assembler source in a
5994 file with an extension of @file{.s}, and also show you exactly how
5995 @command{@value{AS}} is being run.
5998 A description of what behavior you observe that you believe is
5999 incorrect. For example, ``It gets a fatal signal.''
6001 Of course, if the bug is that @command{@value{AS}} gets a fatal signal, then we
6002 will certainly notice it. But if the bug is incorrect output, we might not
6003 notice unless it is glaringly wrong. You might as well not give us a chance to
6006 Even if the problem you experience is a fatal signal, you should still say so
6007 explicitly. Suppose something strange is going on, such as, your copy of
6008 @command{@value{AS}} is out of synch, or you have encountered a bug in the C
6009 library on your system. (This has happened!) Your copy might crash and ours
6010 would not. If you told us to expect a crash, then when ours fails to crash, we
6011 would know that the bug was not happening for us. If you had not told us to
6012 expect a crash, then we would not be able to draw any conclusion from our
6016 If you wish to suggest changes to the @command{@value{AS}} source, send us context
6017 diffs, as generated by @code{diff} with the @samp{-u}, @samp{-c}, or @samp{-p}
6018 option. Always send diffs from the old file to the new file. If you even
6019 discuss something in the @command{@value{AS}} source, refer to it by context, not
6022 The line numbers in our development sources will not match those in your
6023 sources. Your line numbers would convey no useful information to us.
6026 Here are some things that are not necessary:
6030 A description of the envelope of the bug.
6032 Often people who encounter a bug spend a lot of time investigating
6033 which changes to the input file will make the bug go away and which
6034 changes will not affect it.
6036 This is often time consuming and not very useful, because the way we
6037 will find the bug is by running a single example under the debugger
6038 with breakpoints, not by pure deduction from a series of examples.
6039 We recommend that you save your time for something else.
6041 Of course, if you can find a simpler example to report @emph{instead}
6042 of the original one, that is a convenience for us. Errors in the
6043 output will be easier to spot, running under the debugger will take
6044 less time, and so on.
6046 However, simplification is not vital; if you do not want to do this,
6047 report the bug anyway and send us the entire test case you used.
6050 A patch for the bug.
6052 A patch for the bug does help us if it is a good one. But do not omit
6053 the necessary information, such as the test case, on the assumption that
6054 a patch is all we need. We might see problems with your patch and decide
6055 to fix the problem another way, or we might not understand it at all.
6057 Sometimes with a program as complicated as @command{@value{AS}} it is very hard to
6058 construct an example that will make the program follow a certain path through
6059 the code. If you do not send us the example, we will not be able to construct
6060 one, so we will not be able to verify that the bug is fixed.
6062 And if we cannot understand what bug you are trying to fix, or why your
6063 patch should be an improvement, we will not install it. A test case will
6064 help us to understand.
6067 A guess about what the bug is or what it depends on.
6069 Such guesses are usually wrong. Even we cannot guess right about such
6070 things without first using the debugger to find the facts.
6073 @node Acknowledgements
6074 @chapter Acknowledgements
6076 If you have contributed to @command{@value{AS}} and your name isn't listed here,
6077 it is not meant as a slight. We just don't know about it. Send mail to the
6078 maintainer, and we'll correct the situation. Currently
6080 the maintainer is Ken Raeburn (email address @code{raeburn@@cygnus.com}).
6082 Dean Elsner wrote the original @sc{gnu} assembler for the VAX.@footnote{Any
6085 Jay Fenlason maintained GAS for a while, adding support for GDB-specific debug
6086 information and the 68k series machines, most of the preprocessing pass, and
6087 extensive changes in @file{messages.c}, @file{input-file.c}, @file{write.c}.
6089 K. Richard Pixley maintained GAS for a while, adding various enhancements and
6090 many bug fixes, including merging support for several processors, breaking GAS
6091 up to handle multiple object file format back ends (including heavy rewrite,
6092 testing, an integration of the coff and b.out back ends), adding configuration
6093 including heavy testing and verification of cross assemblers and file splits
6094 and renaming, converted GAS to strictly ANSI C including full prototypes, added
6095 support for m680[34]0 and cpu32, did considerable work on i960 including a COFF
6096 port (including considerable amounts of reverse engineering), a SPARC opcode
6097 file rewrite, DECstation, rs6000, and hp300hpux host ports, updated ``know''
6098 assertions and made them work, much other reorganization, cleanup, and lint.
6100 Ken Raeburn wrote the high-level BFD interface code to replace most of the code
6101 in format-specific I/O modules.
6103 The original VMS support was contributed by David L. Kashtan. Eric Youngdale
6104 has done much work with it since.
6106 The Intel 80386 machine description was written by Eliot Dresselhaus.
6108 Minh Tran-Le at IntelliCorp contributed some AIX 386 support.
6110 The Motorola 88k machine description was contributed by Devon Bowen of Buffalo
6111 University and Torbjorn Granlund of the Swedish Institute of Computer Science.
6113 Keith Knowles at the Open Software Foundation wrote the original MIPS back end
6114 (@file{tc-mips.c}, @file{tc-mips.h}), and contributed Rose format support
6115 (which hasn't been merged in yet). Ralph Campbell worked with the MIPS code to
6116 support a.out format.
6118 Support for the Zilog Z8k and Hitachi H8/300 and H8/500 processors (tc-z8k,
6119 tc-h8300, tc-h8500), and IEEE 695 object file format (obj-ieee), was written by
6120 Steve Chamberlain of Cygnus Support. Steve also modified the COFF back end to
6121 use BFD for some low-level operations, for use with the H8/300 and AMD 29k
6124 John Gilmore built the AMD 29000 support, added @code{.include} support, and
6125 simplified the configuration of which versions accept which directives. He
6126 updated the 68k machine description so that Motorola's opcodes always produced
6127 fixed-size instructions (e.g. @code{jsr}), while synthetic instructions
6128 remained shrinkable (@code{jbsr}). John fixed many bugs, including true tested
6129 cross-compilation support, and one bug in relaxation that took a week and
6130 required the proverbial one-bit fix.
6132 Ian Lance Taylor of Cygnus Support merged the Motorola and MIT syntax for the
6133 68k, completed support for some COFF targets (68k, i386 SVR3, and SCO Unix),
6134 added support for MIPS ECOFF and ELF targets, wrote the initial RS/6000 and
6135 PowerPC assembler, and made a few other minor patches.
6137 Steve Chamberlain made @command{@value{AS}} able to generate listings.
6139 Hewlett-Packard contributed support for the HP9000/300.
6141 Jeff Law wrote GAS and BFD support for the native HPPA object format (SOM)
6142 along with a fairly extensive HPPA testsuite (for both SOM and ELF object
6143 formats). This work was supported by both the Center for Software Science at
6144 the University of Utah and Cygnus Support.
6146 Support for ELF format files has been worked on by Mark Eichin of Cygnus
6147 Support (original, incomplete implementation for SPARC), Pete Hoogenboom and
6148 Jeff Law at the University of Utah (HPPA mainly), Michael Meissner of the Open
6149 Software Foundation (i386 mainly), and Ken Raeburn of Cygnus Support (sparc,
6150 and some initial 64-bit support).
6152 Linas Vepstas added GAS support for the ESA/390 "IBM 370" architecture.
6154 Richard Henderson rewrote the Alpha assembler. Klaus Kaempf wrote GAS and BFD
6155 support for openVMS/Alpha.
6157 Timothy Wall, Michael Hayes, and Greg Smart contributed to the various tic*
6160 Several engineers at Cygnus Support have also provided many small bug fixes and
6161 configuration enhancements.
6163 Many others have contributed large or small bugfixes and enhancements. If
6164 you have contributed significant work and are not mentioned on this list, and
6165 want to be, let us know. Some of the history has been lost; we are not
6166 intentionally leaving anyone out.
6168 @node GNU Free Documentation License
6169 @chapter GNU Free Documentation License
6171 GNU Free Documentation License
6173 Version 1.1, March 2000
6175 Copyright (C) 2000 Free Software Foundation, Inc.
6176 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
6178 Everyone is permitted to copy and distribute verbatim copies
6179 of this license document, but changing it is not allowed.
6184 The purpose of this License is to make a manual, textbook, or other
6185 written document "free" in the sense of freedom: to assure everyone
6186 the effective freedom to copy and redistribute it, with or without
6187 modifying it, either commercially or noncommercially. Secondarily,
6188 this License preserves for the author and publisher a way to get
6189 credit for their work, while not being considered responsible for
6190 modifications made by others.
6192 This License is a kind of "copyleft", which means that derivative
6193 works of the document must themselves be free in the same sense. It
6194 complements the GNU General Public License, which is a copyleft
6195 license designed for free software.
6197 We have designed this License in order to use it for manuals for free
6198 software, because free software needs free documentation: a free
6199 program should come with manuals providing the same freedoms that the
6200 software does. But this License is not limited to software manuals;
6201 it can be used for any textual work, regardless of subject matter or
6202 whether it is published as a printed book. We recommend this License
6203 principally for works whose purpose is instruction or reference.
6206 1. APPLICABILITY AND DEFINITIONS
6208 This License applies to any manual or other work that contains a
6209 notice placed by the copyright holder saying it can be distributed
6210 under the terms of this License. The "Document", below, refers to any
6211 such manual or work. Any member of the public is a licensee, and is
6214 A "Modified Version" of the Document means any work containing the
6215 Document or a portion of it, either copied verbatim, or with
6216 modifications and/or translated into another language.
6218 A "Secondary Section" is a named appendix or a front-matter section of
6219 the Document that deals exclusively with the relationship of the
6220 publishers or authors of the Document to the Document's overall subject
6221 (or to related matters) and contains nothing that could fall directly
6222 within that overall subject. (For example, if the Document is in part a
6223 textbook of mathematics, a Secondary Section may not explain any
6224 mathematics.) The relationship could be a matter of historical
6225 connection with the subject or with related matters, or of legal,
6226 commercial, philosophical, ethical or political position regarding
6229 The "Invariant Sections" are certain Secondary Sections whose titles
6230 are designated, as being those of Invariant Sections, in the notice
6231 that says that the Document is released under this License.
6233 The "Cover Texts" are certain short passages of text that are listed,
6234 as Front-Cover Texts or Back-Cover Texts, in the notice that says that
6235 the Document is released under this License.
6237 A "Transparent" copy of the Document means a machine-readable copy,
6238 represented in a format whose specification is available to the
6239 general public, whose contents can be viewed and edited directly and
6240 straightforwardly with generic text editors or (for images composed of
6241 pixels) generic paint programs or (for drawings) some widely available
6242 drawing editor, and that is suitable for input to text formatters or
6243 for automatic translation to a variety of formats suitable for input
6244 to text formatters. A copy made in an otherwise Transparent file
6245 format whose markup has been designed to thwart or discourage
6246 subsequent modification by readers is not Transparent. A copy that is
6247 not "Transparent" is called "Opaque".
6249 Examples of suitable formats for Transparent copies include plain
6250 ASCII without markup, Texinfo input format, LaTeX input format, SGML
6251 or XML using a publicly available DTD, and standard-conforming simple
6252 HTML designed for human modification. Opaque formats include
6253 PostScript, PDF, proprietary formats that can be read and edited only
6254 by proprietary word processors, SGML or XML for which the DTD and/or
6255 processing tools are not generally available, and the
6256 machine-generated HTML produced by some word processors for output
6259 The "Title Page" means, for a printed book, the title page itself,
6260 plus such following pages as are needed to hold, legibly, the material
6261 this License requires to appear in the title page. For works in
6262 formats which do not have any title page as such, "Title Page" means
6263 the text near the most prominent appearance of the work's title,
6264 preceding the beginning of the body of the text.
6269 You may copy and distribute the Document in any medium, either
6270 commercially or noncommercially, provided that this License, the
6271 copyright notices, and the license notice saying this License applies
6272 to the Document are reproduced in all copies, and that you add no other
6273 conditions whatsoever to those of this License. You may not use
6274 technical measures to obstruct or control the reading or further
6275 copying of the copies you make or distribute. However, you may accept
6276 compensation in exchange for copies. If you distribute a large enough
6277 number of copies you must also follow the conditions in section 3.
6279 You may also lend copies, under the same conditions stated above, and
6280 you may publicly display copies.
6283 3. COPYING IN QUANTITY
6285 If you publish printed copies of the Document numbering more than 100,
6286 and the Document's license notice requires Cover Texts, you must enclose
6287 the copies in covers that carry, clearly and legibly, all these Cover
6288 Texts: Front-Cover Texts on the front cover, and Back-Cover Texts on
6289 the back cover. Both covers must also clearly and legibly identify
6290 you as the publisher of these copies. The front cover must present
6291 the full title with all words of the title equally prominent and
6292 visible. You may add other material on the covers in addition.
6293 Copying with changes limited to the covers, as long as they preserve
6294 the title of the Document and satisfy these conditions, can be treated
6295 as verbatim copying in other respects.
6297 If the required texts for either cover are too voluminous to fit
6298 legibly, you should put the first ones listed (as many as fit
6299 reasonably) on the actual cover, and continue the rest onto adjacent
6302 If you publish or distribute Opaque copies of the Document numbering
6303 more than 100, you must either include a machine-readable Transparent
6304 copy along with each Opaque copy, or state in or with each Opaque copy
6305 a publicly-accessible computer-network location containing a complete
6306 Transparent copy of the Document, free of added material, which the
6307 general network-using public has access to download anonymously at no
6308 charge using public-standard network protocols. If you use the latter
6309 option, you must take reasonably prudent steps, when you begin
6310 distribution of Opaque copies in quantity, to ensure that this
6311 Transparent copy will remain thus accessible at the stated location
6312 until at least one year after the last time you distribute an Opaque
6313 copy (directly or through your agents or retailers) of that edition to
6316 It is requested, but not required, that you contact the authors of the
6317 Document well before redistributing any large number of copies, to give
6318 them a chance to provide you with an updated version of the Document.
6323 You may copy and distribute a Modified Version of the Document under
6324 the conditions of sections 2 and 3 above, provided that you release
6325 the Modified Version under precisely this License, with the Modified
6326 Version filling the role of the Document, thus licensing distribution
6327 and modification of the Modified Version to whoever possesses a copy
6328 of it. In addition, you must do these things in the Modified Version:
6330 A. Use in the Title Page (and on the covers, if any) a title distinct
6331 from that of the Document, and from those of previous versions
6332 (which should, if there were any, be listed in the History section
6333 of the Document). You may use the same title as a previous version
6334 if the original publisher of that version gives permission.
6335 B. List on the Title Page, as authors, one or more persons or entities
6336 responsible for authorship of the modifications in the Modified
6337 Version, together with at least five of the principal authors of the
6338 Document (all of its principal authors, if it has less than five).
6339 C. State on the Title page the name of the publisher of the
6340 Modified Version, as the publisher.
6341 D. Preserve all the copyright notices of the Document.
6342 E. Add an appropriate copyright notice for your modifications
6343 adjacent to the other copyright notices.
6344 F. Include, immediately after the copyright notices, a license notice
6345 giving the public permission to use the Modified Version under the
6346 terms of this License, in the form shown in the Addendum below.
6347 G. Preserve in that license notice the full lists of Invariant Sections
6348 and required Cover Texts given in the Document's license notice.
6349 H. Include an unaltered copy of this License.
6350 I. Preserve the section entitled "History", and its title, and add to
6351 it an item stating at least the title, year, new authors, and
6352 publisher of the Modified Version as given on the Title Page. If
6353 there is no section entitled "History" in the Document, create one
6354 stating the title, year, authors, and publisher of the Document as
6355 given on its Title Page, then add an item describing the Modified
6356 Version as stated in the previous sentence.
6357 J. Preserve the network location, if any, given in the Document for
6358 public access to a Transparent copy of the Document, and likewise
6359 the network locations given in the Document for previous versions
6360 it was based on. These may be placed in the "History" section.
6361 You may omit a network location for a work that was published at
6362 least four years before the Document itself, or if the original
6363 publisher of the version it refers to gives permission.
6364 K. In any section entitled "Acknowledgements" or "Dedications",
6365 preserve the section's title, and preserve in the section all the
6366 substance and tone of each of the contributor acknowledgements
6367 and/or dedications given therein.
6368 L. Preserve all the Invariant Sections of the Document,
6369 unaltered in their text and in their titles. Section numbers
6370 or the equivalent are not considered part of the section titles.
6371 M. Delete any section entitled "Endorsements". Such a section
6372 may not be included in the Modified Version.
6373 N. Do not retitle any existing section as "Endorsements"
6374 or to conflict in title with any Invariant Section.
6376 If the Modified Version includes new front-matter sections or
6377 appendices that qualify as Secondary Sections and contain no material
6378 copied from the Document, you may at your option designate some or all
6379 of these sections as invariant. To do this, add their titles to the
6380 list of Invariant Sections in the Modified Version's license notice.
6381 These titles must be distinct from any other section titles.
6383 You may add a section entitled "Endorsements", provided it contains
6384 nothing but endorsements of your Modified Version by various
6385 parties--for example, statements of peer review or that the text has
6386 been approved by an organization as the authoritative definition of a
6389 You may add a passage of up to five words as a Front-Cover Text, and a
6390 passage of up to 25 words as a Back-Cover Text, to the end of the list
6391 of Cover Texts in the Modified Version. Only one passage of
6392 Front-Cover Text and one of Back-Cover Text may be added by (or
6393 through arrangements made by) any one entity. If the Document already
6394 includes a cover text for the same cover, previously added by you or
6395 by arrangement made by the same entity you are acting on behalf of,
6396 you may not add another; but you may replace the old one, on explicit
6397 permission from the previous publisher that added the old one.
6399 The author(s) and publisher(s) of the Document do not by this License
6400 give permission to use their names for publicity for or to assert or
6401 imply endorsement of any Modified Version.
6404 5. COMBINING DOCUMENTS
6406 You may combine the Document with other documents released under this
6407 License, under the terms defined in section 4 above for modified
6408 versions, provided that you include in the combination all of the
6409 Invariant Sections of all of the original documents, unmodified, and
6410 list them all as Invariant Sections of your combined work in its
6413 The combined work need only contain one copy of this License, and
6414 multiple identical Invariant Sections may be replaced with a single
6415 copy. If there are multiple Invariant Sections with the same name but
6416 different contents, make the title of each such section unique by
6417 adding at the end of it, in parentheses, the name of the original
6418 author or publisher of that section if known, or else a unique number.
6419 Make the same adjustment to the section titles in the list of
6420 Invariant Sections in the license notice of the combined work.
6422 In the combination, you must combine any sections entitled "History"
6423 in the various original documents, forming one section entitled
6424 "History"; likewise combine any sections entitled "Acknowledgements",
6425 and any sections entitled "Dedications". You must delete all sections
6426 entitled "Endorsements."
6429 6. COLLECTIONS OF DOCUMENTS
6431 You may make a collection consisting of the Document and other documents
6432 released under this License, and replace the individual copies of this
6433 License in the various documents with a single copy that is included in
6434 the collection, provided that you follow the rules of this License for
6435 verbatim copying of each of the documents in all other respects.
6437 You may extract a single document from such a collection, and distribute
6438 it individually under this License, provided you insert a copy of this
6439 License into the extracted document, and follow this License in all
6440 other respects regarding verbatim copying of that document.
6443 7. AGGREGATION WITH INDEPENDENT WORKS
6445 A compilation of the Document or its derivatives with other separate
6446 and independent documents or works, in or on a volume of a storage or
6447 distribution medium, does not as a whole count as a Modified Version
6448 of the Document, provided no compilation copyright is claimed for the
6449 compilation. Such a compilation is called an "aggregate", and this
6450 License does not apply to the other self-contained works thus compiled
6451 with the Document, on account of their being thus compiled, if they
6452 are not themselves derivative works of the Document.
6454 If the Cover Text requirement of section 3 is applicable to these
6455 copies of the Document, then if the Document is less than one quarter
6456 of the entire aggregate, the Document's Cover Texts may be placed on
6457 covers that surround only the Document within the aggregate.
6458 Otherwise they must appear on covers around the whole aggregate.
6463 Translation is considered a kind of modification, so you may
6464 distribute translations of the Document under the terms of section 4.
6465 Replacing Invariant Sections with translations requires special
6466 permission from their copyright holders, but you may include
6467 translations of some or all Invariant Sections in addition to the
6468 original versions of these Invariant Sections. You may include a
6469 translation of this License provided that you also include the
6470 original English version of this License. In case of a disagreement
6471 between the translation and the original English version of this
6472 License, the original English version will prevail.
6477 You may not copy, modify, sublicense, or distribute the Document except
6478 as expressly provided for under this License. Any other attempt to
6479 copy, modify, sublicense or distribute the Document is void, and will
6480 automatically terminate your rights under this License. However,
6481 parties who have received copies, or rights, from you under this
6482 License will not have their licenses terminated so long as such
6483 parties remain in full compliance.
6486 10. FUTURE REVISIONS OF THIS LICENSE
6488 The Free Software Foundation may publish new, revised versions
6489 of the GNU Free Documentation License from time to time. Such new
6490 versions will be similar in spirit to the present version, but may
6491 differ in detail to address new problems or concerns. See
6492 http://www.gnu.org/copyleft/.
6494 Each version of the License is given a distinguishing version number.
6495 If the Document specifies that a particular numbered version of this
6496 License "or any later version" applies to it, you have the option of
6497 following the terms and conditions either of that specified version or
6498 of any later version that has been published (not as a draft) by the
6499 Free Software Foundation. If the Document does not specify a version
6500 number of this License, you may choose any version ever published (not
6501 as a draft) by the Free Software Foundation.
6504 ADDENDUM: How to use this License for your documents
6506 To use this License in a document you have written, include a copy of
6507 the License in the document and put the following copyright and
6508 license notices just after the title page:
6511 Copyright (c) YEAR YOUR NAME.
6512 Permission is granted to copy, distribute and/or modify this document
6513 under the terms of the GNU Free Documentation License, Version 1.1
6514 or any later version published by the Free Software Foundation;
6515 with the Invariant Sections being LIST THEIR TITLES, with the
6516 Front-Cover Texts being LIST, and with the Back-Cover Texts being LIST.
6517 A copy of the license is included in the section entitled "GNU
6518 Free Documentation License".
6521 If you have no Invariant Sections, write "with no Invariant Sections"
6522 instead of saying which ones are invariant. If you have no
6523 Front-Cover Texts, write "no Front-Cover Texts" instead of
6524 "Front-Cover Texts being LIST"; likewise for Back-Cover Texts.
6526 If your document contains nontrivial examples of program code, we
6527 recommend releasing these examples in parallel under your choice of
6528 free software license, such as the GNU General Public License,
6529 to permit their use in free software.
projects / external / binutils.git / blob