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{--trap}] [@b{--break}] [@b{-n}]
378 [@b{--emulation}=@var{name} ]
382 @emph{Target MMIX options:}
383 [@b{--fixed-special-register-names}] [@b{--globalize-symbols}]
384 [@b{--gnu-syntax}] [@b{--relax}] [@b{--no-predefined-symbols}]
385 [@b{--no-expand}] [@b{--no-merge-gregs}] [@b{-x}]
386 [@b{--linker-allocated-gregs}]
390 @emph{Target PDP11 options:}
391 [@b{-mpic}|@b{-mno-pic}] [@b{-mall}] [@b{-mno-extensions}]
392 [@b{-m}@var{extension}|@b{-mno-}@var{extension}]
393 [@b{-m}@var{cpu}] [@b{-m}@var{machine}]
397 @emph{Target picoJava options:}
402 @emph{Target PowerPC options:}
403 [@b{-mpwrx}|@b{-mpwr2}|@b{-mpwr}|@b{-m601}|@b{-mppc}|@b{-mppc32}|@b{-m603}|@b{-m604}|
404 @b{-m403}|@b{-m405}|@b{-mppc64}|@b{-m620}|@b{-mppc64bridge}|@b{-mbooke}|
405 @b{-mbooke32}|@b{-mbooke64}]
406 [@b{-mcom}|@b{-many}|@b{-maltivec}] [@b{-memb}]
407 [@b{-mregnames}|@b{-mno-regnames}]
408 [@b{-mrelocatable}|@b{-mrelocatable-lib}]
409 [@b{-mlittle}|@b{-mlittle-endian}|@b{-mbig}|@b{-mbig-endian}]
410 [@b{-msolaris}|@b{-mno-solaris}]
414 @emph{Target SPARC options:}
415 @c The order here is important. See c-sparc.texi.
416 [@b{-Av6}|@b{-Av7}|@b{-Av8}|@b{-Asparclet}|@b{-Asparclite}
417 @b{-Av8plus}|@b{-Av8plusa}|@b{-Av9}|@b{-Av9a}]
418 [@b{-xarch=v8plus}|@b{-xarch=v8plusa}] [@b{-bump}]
423 @emph{Target TIC54X options:}
424 [@b{-mcpu=54[123589]}|@b{-mcpu=54[56]lp}] [@b{-mfar-mode}|@b{-mf}]
425 [@b{-merrors-to-file} @var{<filename>}|@b{-me} @var{<filename>}]
428 @c Z8000 has no machine-dependent assembler options
437 Turn on listings, in any of a variety of ways:
441 omit false conditionals
444 omit debugging directives
447 include high-level source
453 include macro expansions
456 omit forms processing
462 set the name of the listing file
465 You may combine these options; for example, use @samp{-aln} for assembly
466 listing without forms processing. The @samp{=file} option, if used, must be
467 the last one. By itself, @samp{-a} defaults to @samp{-ahls}.
470 Ignored. This option is accepted for script compatibility with calls to
473 @item --defsym @var{sym}=@var{value}
474 Define the symbol @var{sym} to be @var{value} before assembling the input file.
475 @var{value} must be an integer constant. As in C, a leading @samp{0x}
476 indicates a hexadecimal value, and a leading @samp{0} indicates an octal value.
479 ``fast''---skip whitespace and comment preprocessing (assume source is
483 Generate stabs debugging information for each assembler line. This
484 may help debugging assembler code, if the debugger can handle it.
487 Generate DWARF2 debugging information for each assembler line. This
488 may help debugging assembler code, if the debugger can handle it. Note - this
489 option is only supported by some targets, not all of them.
492 Print a summary of the command line options and exit.
495 Print a summary of all target specific options and exit.
498 Add directory @var{dir} to the search list for @code{.include} directives.
501 Don't warn about signed overflow.
504 @ifclear DIFF-TBL-KLUGE
505 This option is accepted but has no effect on the @value{TARGET} family.
507 @ifset DIFF-TBL-KLUGE
508 Issue warnings when difference tables altered for long displacements.
513 Keep (in the symbol table) local symbols. On traditional a.out systems
514 these start with @samp{L}, but different systems have different local
517 @item --listing-lhs-width=@var{number}
518 Set the maximum width, in words, of the output data column for an assembler
519 listing to @var{number}.
521 @item --listing-lhs-width2=@var{number}
522 Set the maximum width, in words, of the output data column for continuation
523 lines in an assembler listing to @var{number}.
525 @item --listing-rhs-width=@var{number}
526 Set the maximum width of an input source line, as displayed in a listing, to
529 @item --listing-cont-lines=@var{number}
530 Set the maximum number of lines printed in a listing for a single line of input
533 @item -o @var{objfile}
534 Name the object-file output from @command{@value{AS}} @var{objfile}.
537 Fold the data section into the text section.
540 Print the maximum space (in bytes) and total time (in seconds) used by
543 @item --strip-local-absolute
544 Remove local absolute symbols from the outgoing symbol table.
548 Print the @command{as} version.
551 Print the @command{as} version and exit.
555 Suppress warning messages.
557 @item --fatal-warnings
558 Treat warnings as errors.
561 Don't suppress warning messages or treat them as errors.
570 Generate an object file even after errors.
572 @item -- | @var{files} @dots{}
573 Standard input, or source files to assemble.
578 The following options are available when @value{AS} is configured for
583 This option selects the core processor variant.
585 Select either big-endian (-EB) or little-endian (-EL) output.
590 The following options are available when @value{AS} is configured for the ARM
594 @item -mcpu=@var{processor}[+@var{extension}@dots{}]
595 Specify which ARM processor variant is the target.
596 @item -march=@var{architecture}[+@var{extension}@dots{}]
597 Specify which ARM architecture variant is used by the target.
598 @item -mfpu=@var{floating-point-format}
599 Select which Floating Point architecture is the target.
601 Enable Thumb only instruction decoding.
602 @item -mapcs-32 | -mapcs-26 | -mapcs-float | -mapcs-reentrant | -moabi
603 Select which procedure calling convention is in use.
605 Select either big-endian (-EB) or little-endian (-EL) output.
606 @item -mthumb-interwork
607 Specify that the code has been generated with interworking between Thumb and
610 Specify that PIC code has been generated.
615 See the info pages for documentation of the CRIS-specific options.
619 The following options are available when @value{AS} is configured for
622 @cindex D10V optimization
623 @cindex optimization, D10V
625 Optimize output by parallelizing instructions.
630 The following options are available when @value{AS} is configured for a D30V
633 @cindex D30V optimization
634 @cindex optimization, D30V
636 Optimize output by parallelizing instructions.
640 Warn when nops are generated.
642 @cindex D30V nops after 32-bit multiply
644 Warn when a nop after a 32-bit multiply instruction is generated.
649 The following options are available when @value{AS} is configured for the
650 Intel 80960 processor.
653 @item -ACA | -ACA_A | -ACB | -ACC | -AKA | -AKB | -AKC | -AMC
654 Specify which variant of the 960 architecture is the target.
657 Add code to collect statistics about branches taken.
660 Do not alter compare-and-branch instructions for long displacements;
667 The following options are available when @value{AS} is configured for the
668 Mitsubishi M32R series.
673 Specify which processor in the M32R family is the target. The default
674 is normally the M32R, but this option changes it to the M32RX.
676 @item --warn-explicit-parallel-conflicts or --Wp
677 Produce warning messages when questionable parallel constructs are
680 @item --no-warn-explicit-parallel-conflicts or --Wnp
681 Do not produce warning messages when questionable parallel constructs are
688 The following options are available when @value{AS} is configured for the
689 Motorola 68000 series.
694 Shorten references to undefined symbols, to one word instead of two.
696 @item -m68000 | -m68008 | -m68010 | -m68020 | -m68030
697 @itemx | -m68040 | -m68060 | -m68302 | -m68331 | -m68332
698 @itemx | -m68333 | -m68340 | -mcpu32 | -m5200
699 Specify what processor in the 68000 family is the target. The default
700 is normally the 68020, but this can be changed at configuration time.
702 @item -m68881 | -m68882 | -mno-68881 | -mno-68882
703 The target machine does (or does not) have a floating-point coprocessor.
704 The default is to assume a coprocessor for 68020, 68030, and cpu32. Although
705 the basic 68000 is not compatible with the 68881, a combination of the
706 two can be specified, since it's possible to do emulation of the
707 coprocessor instructions with the main processor.
709 @item -m68851 | -mno-68851
710 The target machine does (or does not) have a memory-management
711 unit coprocessor. The default is to assume an MMU for 68020 and up.
718 For details about the PDP-11 machine dependent features options,
719 see @ref{PDP-11-Options}.
722 @item -mpic | -mno-pic
723 Generate position-independent (or position-dependent) code. The
724 default is @option{-mpic}.
727 @itemx -mall-extensions
728 Enable all instruction set extensions. This is the default.
730 @item -mno-extensions
731 Disable all instruction set extensions.
733 @item -m@var{extension} | -mno-@var{extension}
734 Enable (or disable) a particular instruction set extension.
737 Enable the instruction set extensions supported by a particular CPU, and
738 disable all other extensions.
740 @item -m@var{machine}
741 Enable the instruction set extensions supported by a particular machine
742 model, and disable all other extensions.
748 The following options are available when @value{AS} is configured for
749 a picoJava processor.
753 @cindex PJ endianness
754 @cindex endianness, PJ
755 @cindex big endian output, PJ
757 Generate ``big endian'' format output.
759 @cindex little endian output, PJ
761 Generate ``little endian'' format output.
767 The following options are available when @value{AS} is configured for the
768 Motorola 68HC11 or 68HC12 series.
772 @item -m68hc11 | -m68hc12
773 Specify what processor is the target. The default is
774 defined by the configuration option when building the assembler.
776 @item --force-long-branchs
777 Relative branches are turned into absolute ones. This concerns
778 conditional branches, unconditional branches and branches to a
781 @item -S | --short-branchs
782 Do not turn relative branchs into absolute ones
783 when the offset is out of range.
785 @item --strict-direct-mode
786 Do not turn the direct addressing mode into extended addressing mode
787 when the instruction does not support direct addressing mode.
789 @item --print-insn-syntax
790 Print the syntax of instruction in case of error.
792 @item --print-opcodes
793 print the list of instructions with syntax and then exit.
795 @item --generate-example
796 print an example of instruction for each possible instruction and then exit.
797 This option is only useful for testing @command{@value{AS}}.
803 The following options are available when @command{@value{AS}} is configured
804 for the SPARC architecture:
807 @item -Av6 | -Av7 | -Av8 | -Asparclet | -Asparclite
808 @itemx -Av8plus | -Av8plusa | -Av9 | -Av9a
809 Explicitly select a variant of the SPARC architecture.
811 @samp{-Av8plus} and @samp{-Av8plusa} select a 32 bit environment.
812 @samp{-Av9} and @samp{-Av9a} select a 64 bit environment.
814 @samp{-Av8plusa} and @samp{-Av9a} enable the SPARC V9 instruction set with
815 UltraSPARC extensions.
817 @item -xarch=v8plus | -xarch=v8plusa
818 For compatibility with the Solaris v9 assembler. These options are
819 equivalent to -Av8plus and -Av8plusa, respectively.
822 Warn when the assembler switches to another architecture.
827 The following options are available when @value{AS} is configured for the 'c54x
832 Enable extended addressing mode. All addresses and relocations will assume
833 extended addressing (usually 23 bits).
834 @item -mcpu=@var{CPU_VERSION}
835 Sets the CPU version being compiled for.
836 @item -merrors-to-file @var{FILENAME}
837 Redirect error output to a file, for broken systems which don't support such
838 behaviour in the shell.
843 The following options are available when @value{AS} is configured for
848 This option sets the largest size of an object that can be referenced
849 implicitly with the @code{gp} register. It is only accepted for targets that
850 use ECOFF format, such as a DECstation running Ultrix. The default value is 8.
852 @cindex MIPS endianness
853 @cindex endianness, MIPS
854 @cindex big endian output, MIPS
856 Generate ``big endian'' format output.
858 @cindex little endian output, MIPS
860 Generate ``little endian'' format output.
869 Generate code for a particular MIPS Instruction Set Architecture level.
870 @samp{-mips1} corresponds to the @sc{r2000} and @sc{r3000} processors,
871 @samp{-mips2} to the @sc{r6000} processor, and @samp{-mips3} to the @sc{r4000}
873 @samp{-mips5}, @samp{-mips32}, and @samp{-mips64} correspond
874 to generic @sc{MIPS V}, @sc{MIPS32}, and @sc{MIPS64} ISA
875 processors, respectively.
879 Generate code for the MIPS @sc{r4650} chip. This tells the assembler to accept
880 the @samp{mad} and @samp{madu} instruction, and to not schedule @samp{nop}
881 instructions around accesses to the @samp{HI} and @samp{LO} registers.
882 @samp{-no-m4650} turns off this option.
884 @item -mcpu=@var{CPU}
885 Generate code for a particular MIPS cpu. It is exactly equivalent to
886 @samp{-m@var{cpu}}, except that there are more value of @var{cpu}
890 @item --emulation=@var{name}
891 This option causes @command{@value{AS}} to emulate @command{@value{AS}} configured
892 for some other target, in all respects, including output format (choosing
893 between ELF and ECOFF only), handling of pseudo-opcodes which may generate
894 debugging information or store symbol table information, and default
895 endianness. The available configuration names are: @samp{mipsecoff},
896 @samp{mipself}, @samp{mipslecoff}, @samp{mipsbecoff}, @samp{mipslelf},
897 @samp{mipsbelf}. The first two do not alter the default endianness from that
898 of the primary target for which the assembler was configured; the others change
899 the default to little- or big-endian as indicated by the @samp{b} or @samp{l}
900 in the name. Using @samp{-EB} or @samp{-EL} will override the endianness
901 selection in any case.
903 This option is currently supported only when the primary target
904 @command{@value{AS}} is configured for is a MIPS ELF or ECOFF target.
905 Furthermore, the primary target or others specified with
906 @samp{--enable-targets=@dots{}} at configuration time must include support for
907 the other format, if both are to be available. For example, the Irix 5
908 configuration includes support for both.
910 Eventually, this option will support more configurations, with more
911 fine-grained control over the assembler's behavior, and will be supported for
915 @command{@value{AS}} ignores this option. It is accepted for compatibility with
923 Control how to deal with multiplication overflow and division by zero.
924 @samp{--trap} or @samp{--no-break} (which are synonyms) take a trap exception
925 (and only work for Instruction Set Architecture level 2 and higher);
926 @samp{--break} or @samp{--no-trap} (also synonyms, and the default) take a
930 When this option is used, @command{@value{AS}} will issue a warning every
931 time it generates a nop instruction from a macro.
936 The following options are available when @value{AS} is configured for
942 Enable or disable the JSRI to BSR transformation. By default this is enabled.
943 The command line option @samp{-nojsri2bsr} can be used to disable it.
947 Enable or disable the silicon filter behaviour. By default this is disabled.
948 The default can be overridden by the @samp{-sifilter} command line option.
951 Alter jump instructions for long displacements.
953 @item -mcpu=[210|340]
954 Select the cpu type on the target hardware. This controls which instructions
958 Assemble for a big endian target.
961 Assemble for a little endian target.
967 See the info pages for documentation of the MMIX-specific options.
973 * Manual:: Structure of this Manual
974 * GNU Assembler:: The GNU Assembler
975 * Object Formats:: Object File Formats
976 * Command Line:: Command Line
977 * Input Files:: Input Files
978 * Object:: Output (Object) File
979 * Errors:: Error and Warning Messages
983 @section Structure of this Manual
985 @cindex manual, structure and purpose
986 This manual is intended to describe what you need to know to use
987 @sc{gnu} @command{@value{AS}}. We cover the syntax expected in source files, including
988 notation for symbols, constants, and expressions; the directives that
989 @command{@value{AS}} understands; and of course how to invoke @command{@value{AS}}.
992 We also cover special features in the @value{TARGET}
993 configuration of @command{@value{AS}}, including assembler directives.
996 This manual also describes some of the machine-dependent features of
997 various flavors of the assembler.
1000 @cindex machine instructions (not covered)
1001 On the other hand, this manual is @emph{not} intended as an introduction
1002 to programming in assembly language---let alone programming in general!
1003 In a similar vein, we make no attempt to introduce the machine
1004 architecture; we do @emph{not} describe the instruction set, standard
1005 mnemonics, registers or addressing modes that are standard to a
1006 particular architecture.
1008 You may want to consult the manufacturer's
1009 machine architecture manual for this information.
1013 For information on the H8/300 machine instruction set, see @cite{H8/300
1014 Series Programming Manual} (Hitachi ADE--602--025). For the H8/300H,
1015 see @cite{H8/300H Series Programming Manual} (Hitachi).
1018 For information on the H8/500 machine instruction set, see @cite{H8/500
1019 Series Programming Manual} (Hitachi M21T001).
1022 For information on the Hitachi SH machine instruction set, see
1023 @cite{SH-Microcomputer User's Manual} (Hitachi Micro Systems, Inc.).
1026 For information on the Z8000 machine instruction set, see @cite{Z8000 CPU Technical Manual}
1030 @c I think this is premature---doc@cygnus.com, 17jan1991
1032 Throughout this manual, we assume that you are running @dfn{GNU},
1033 the portable operating system from the @dfn{Free Software
1034 Foundation, Inc.}. This restricts our attention to certain kinds of
1035 computer (in particular, the kinds of computers that @sc{gnu} can run on);
1036 once this assumption is granted examples and definitions need less
1039 @command{@value{AS}} is part of a team of programs that turn a high-level
1040 human-readable series of instructions into a low-level
1041 computer-readable series of instructions. Different versions of
1042 @command{@value{AS}} are used for different kinds of computer.
1045 @c There used to be a section "Terminology" here, which defined
1046 @c "contents", "byte", "word", and "long". Defining "word" to any
1047 @c particular size is confusing when the .word directive may generate 16
1048 @c bits on one machine and 32 bits on another; in general, for the user
1049 @c version of this manual, none of these terms seem essential to define.
1050 @c They were used very little even in the former draft of the manual;
1051 @c this draft makes an effort to avoid them (except in names of
1055 @section The GNU Assembler
1057 @c man begin DESCRIPTION
1059 @sc{gnu} @command{as} is really a family of assemblers.
1061 This manual describes @command{@value{AS}}, a member of that family which is
1062 configured for the @value{TARGET} architectures.
1064 If you use (or have used) the @sc{gnu} assembler on one architecture, you
1065 should find a fairly similar environment when you use it on another
1066 architecture. Each version has much in common with the others,
1067 including object file formats, most assembler directives (often called
1068 @dfn{pseudo-ops}) and assembler syntax.@refill
1070 @cindex purpose of @sc{gnu} assembler
1071 @command{@value{AS}} is primarily intended to assemble the output of the
1072 @sc{gnu} C compiler @code{@value{GCC}} for use by the linker
1073 @code{@value{LD}}. Nevertheless, we've tried to make @command{@value{AS}}
1074 assemble correctly everything that other assemblers for the same
1075 machine would assemble.
1077 Any exceptions are documented explicitly (@pxref{Machine Dependencies}).
1080 @c This remark should appear in generic version of manual; assumption
1081 @c here is that generic version sets M680x0.
1082 This doesn't mean @command{@value{AS}} always uses the same syntax as another
1083 assembler for the same architecture; for example, we know of several
1084 incompatible versions of 680x0 assembly language syntax.
1089 Unlike older assemblers, @command{@value{AS}} is designed to assemble a source
1090 program in one pass of the source file. This has a subtle impact on the
1091 @kbd{.org} directive (@pxref{Org,,@code{.org}}).
1093 @node Object Formats
1094 @section Object File Formats
1096 @cindex object file format
1097 The @sc{gnu} assembler can be configured to produce several alternative
1098 object file formats. For the most part, this does not affect how you
1099 write assembly language programs; but directives for debugging symbols
1100 are typically different in different file formats. @xref{Symbol
1101 Attributes,,Symbol Attributes}.
1104 On the @value{TARGET}, @command{@value{AS}} is configured to produce
1105 @value{OBJ-NAME} format object files.
1107 @c The following should exhaust all configs that set MULTI-OBJ, ideally
1109 On the @value{TARGET}, @command{@value{AS}} can be configured to produce either
1110 @code{a.out} or COFF format object files.
1113 On the @value{TARGET}, @command{@value{AS}} can be configured to produce either
1114 @code{b.out} or COFF format object files.
1117 On the @value{TARGET}, @command{@value{AS}} can be configured to produce either
1118 SOM or ELF format object files.
1123 @section Command Line
1125 @cindex command line conventions
1127 After the program name @command{@value{AS}}, the command line may contain
1128 options and file names. Options may appear in any order, and may be
1129 before, after, or between file names. The order of file names is
1132 @cindex standard input, as input file
1134 @file{--} (two hyphens) by itself names the standard input file
1135 explicitly, as one of the files for @command{@value{AS}} to assemble.
1137 @cindex options, command line
1138 Except for @samp{--} any command line argument that begins with a
1139 hyphen (@samp{-}) is an option. Each option changes the behavior of
1140 @command{@value{AS}}. No option changes the way another option works. An
1141 option is a @samp{-} followed by one or more letters; the case of
1142 the letter is important. All options are optional.
1144 Some options expect exactly one file name to follow them. The file
1145 name may either immediately follow the option's letter (compatible
1146 with older assemblers) or it may be the next command argument (@sc{gnu}
1147 standard). These two command lines are equivalent:
1150 @value{AS} -o my-object-file.o mumble.s
1151 @value{AS} -omy-object-file.o mumble.s
1155 @section Input Files
1158 @cindex source program
1159 @cindex files, input
1160 We use the phrase @dfn{source program}, abbreviated @dfn{source}, to
1161 describe the program input to one run of @command{@value{AS}}. The program may
1162 be in one or more files; how the source is partitioned into files
1163 doesn't change the meaning of the source.
1165 @c I added "con" prefix to "catenation" just to prove I can overcome my
1166 @c APL training... doc@cygnus.com
1167 The source program is a concatenation of the text in all the files, in the
1170 @c man begin DESCRIPTION
1171 Each time you run @command{@value{AS}} it assembles exactly one source
1172 program. The source program is made up of one or more files.
1173 (The standard input is also a file.)
1175 You give @command{@value{AS}} a command line that has zero or more input file
1176 names. The input files are read (from left file name to right). A
1177 command line argument (in any position) that has no special meaning
1178 is taken to be an input file name.
1180 If you give @command{@value{AS}} no file names it attempts to read one input file
1181 from the @command{@value{AS}} standard input, which is normally your terminal. You
1182 may have to type @key{ctl-D} to tell @command{@value{AS}} there is no more program
1185 Use @samp{--} if you need to explicitly name the standard input file
1186 in your command line.
1188 If the source is empty, @command{@value{AS}} produces a small, empty object
1193 @subheading Filenames and Line-numbers
1195 @cindex input file linenumbers
1196 @cindex line numbers, in input files
1197 There are two ways of locating a line in the input file (or files) and
1198 either may be used in reporting error messages. One way refers to a line
1199 number in a physical file; the other refers to a line number in a
1200 ``logical'' file. @xref{Errors, ,Error and Warning Messages}.
1202 @dfn{Physical files} are those files named in the command line given
1203 to @command{@value{AS}}.
1205 @dfn{Logical files} are simply names declared explicitly by assembler
1206 directives; they bear no relation to physical files. Logical file names help
1207 error messages reflect the original source file, when @command{@value{AS}} source
1208 is itself synthesized from other files. @command{@value{AS}} understands the
1209 @samp{#} directives emitted by the @code{@value{GCC}} preprocessor. See also
1210 @ref{File,,@code{.file}}.
1213 @section Output (Object) File
1219 Every time you run @command{@value{AS}} it produces an output file, which is
1220 your assembly language program translated into numbers. This file
1221 is the object file. Its default name is
1229 @code{b.out} when @command{@value{AS}} is configured for the Intel 80960.
1231 You can give it another name by using the @option{-o} option. Conventionally,
1232 object file names end with @file{.o}. The default name is used for historical
1233 reasons: older assemblers were capable of assembling self-contained programs
1234 directly into a runnable program. (For some formats, this isn't currently
1235 possible, but it can be done for the @code{a.out} format.)
1239 The object file is meant for input to the linker @code{@value{LD}}. It contains
1240 assembled program code, information to help @code{@value{LD}} integrate
1241 the assembled program into a runnable file, and (optionally) symbolic
1242 information for the debugger.
1244 @c link above to some info file(s) like the description of a.out.
1245 @c don't forget to describe @sc{gnu} info as well as Unix lossage.
1248 @section Error and Warning Messages
1250 @c man begin DESCRIPTION
1252 @cindex error messages
1253 @cindex warning messages
1254 @cindex messages from assembler
1255 @command{@value{AS}} may write warnings and error messages to the standard error
1256 file (usually your terminal). This should not happen when a compiler
1257 runs @command{@value{AS}} automatically. Warnings report an assumption made so
1258 that @command{@value{AS}} could keep assembling a flawed program; errors report a
1259 grave problem that stops the assembly.
1263 @cindex format of warning messages
1264 Warning messages have the format
1267 file_name:@b{NNN}:Warning Message Text
1271 @cindex line numbers, in warnings/errors
1272 (where @b{NNN} is a line number). If a logical file name has been given
1273 (@pxref{File,,@code{.file}}) it is used for the filename, otherwise the name of
1274 the current input file is used. If a logical line number was given
1276 (@pxref{Line,,@code{.line}})
1280 (@pxref{Line,,@code{.line}})
1283 (@pxref{Ln,,@code{.ln}})
1286 then it is used to calculate the number printed,
1287 otherwise the actual line in the current source file is printed. The
1288 message text is intended to be self explanatory (in the grand Unix
1291 @cindex format of error messages
1292 Error messages have the format
1294 file_name:@b{NNN}:FATAL:Error Message Text
1296 The file name and line number are derived as for warning
1297 messages. The actual message text may be rather less explanatory
1298 because many of them aren't supposed to happen.
1301 @chapter Command-Line Options
1303 @cindex options, all versions of assembler
1304 This chapter describes command-line options available in @emph{all}
1305 versions of the @sc{gnu} assembler; @pxref{Machine Dependencies}, for options specific
1307 to the @value{TARGET}.
1310 to particular machine architectures.
1313 @c man begin DESCRIPTION
1315 If you are invoking @command{@value{AS}} via the @sc{gnu} C compiler (version 2),
1316 you can use the @samp{-Wa} option to pass arguments through to the assembler.
1317 The assembler arguments must be separated from each other (and the @samp{-Wa})
1318 by commas. For example:
1321 gcc -c -g -O -Wa,-alh,-L file.c
1325 This passes two options to the assembler: @samp{-alh} (emit a listing to
1326 standard output with with high-level and assembly source) and @samp{-L} (retain
1327 local symbols in the symbol table).
1329 Usually you do not need to use this @samp{-Wa} mechanism, since many compiler
1330 command-line options are automatically passed to the assembler by the compiler.
1331 (You can call the @sc{gnu} compiler driver with the @samp{-v} option to see
1332 precisely what options it passes to each compilation pass, including the
1338 * a:: -a[cdhlns] enable listings
1339 * D:: -D for compatibility
1340 * f:: -f to work faster
1341 * I:: -I for .include search path
1342 @ifclear DIFF-TBL-KLUGE
1343 * K:: -K for compatibility
1345 @ifset DIFF-TBL-KLUGE
1346 * K:: -K for difference tables
1349 * L:: -L to retain local labels
1350 * listing:: --listing-XXX to configure listing output
1351 * M:: -M or --mri to assemble in MRI compatibility mode
1352 * MD:: --MD for dependency tracking
1353 * o:: -o to name the object file
1354 * R:: -R to join data and text sections
1355 * statistics:: --statistics to see statistics about assembly
1356 * traditional-format:: --traditional-format for compatible output
1357 * v:: -v to announce version
1358 * W:: -W, --no-warn, --warn, --fatal-warnings to control warnings
1359 * Z:: -Z to make object file even after errors
1363 @section Enable Listings: @option{-a[cdhlns]}
1372 @cindex listings, enabling
1373 @cindex assembly listings, enabling
1375 These options enable listing output from the assembler. By itself,
1376 @samp{-a} requests high-level, assembly, and symbols listing.
1377 You can use other letters to select specific options for the list:
1378 @samp{-ah} requests a high-level language listing,
1379 @samp{-al} requests an output-program assembly listing, and
1380 @samp{-as} requests a symbol table listing.
1381 High-level listings require that a compiler debugging option like
1382 @samp{-g} be used, and that assembly listings (@samp{-al}) be requested
1385 Use the @samp{-ac} option to omit false conditionals from a listing. Any lines
1386 which are not assembled because of a false @code{.if} (or @code{.ifdef}, or any
1387 other conditional), or a true @code{.if} followed by an @code{.else}, will be
1388 omitted from the listing.
1390 Use the @samp{-ad} option to omit debugging directives from the
1393 Once you have specified one of these options, you can further control
1394 listing output and its appearance using the directives @code{.list},
1395 @code{.nolist}, @code{.psize}, @code{.eject}, @code{.title}, and
1397 The @samp{-an} option turns off all forms processing.
1398 If you do not request listing output with one of the @samp{-a} options, the
1399 listing-control directives have no effect.
1401 The letters after @samp{-a} may be combined into one option,
1402 @emph{e.g.}, @samp{-aln}.
1404 Note if the assembler source is coming from the standard input (eg because it
1405 is being created by @code{@value{GCC}} and the @samp{-pipe} command line switch
1406 is being used) then the listing will not contain any comments or preprocessor
1407 directives. This is because the listing code buffers input source lines from
1408 stdin only after they have been preprocessed by the assembler. This reduces
1409 memory usage and makes the code more efficient.
1412 @section @option{-D}
1415 This option has no effect whatsoever, but it is accepted to make it more
1416 likely that scripts written for other assemblers also work with
1417 @command{@value{AS}}.
1420 @section Work Faster: @option{-f}
1423 @cindex trusted compiler
1424 @cindex faster processing (@option{-f})
1425 @samp{-f} should only be used when assembling programs written by a
1426 (trusted) compiler. @samp{-f} stops the assembler from doing whitespace
1427 and comment preprocessing on
1428 the input file(s) before assembling them. @xref{Preprocessing,
1432 @emph{Warning:} if you use @samp{-f} when the files actually need to be
1433 preprocessed (if they contain comments, for example), @command{@value{AS}} does
1438 @section @code{.include} search path: @option{-I} @var{path}
1440 @kindex -I @var{path}
1441 @cindex paths for @code{.include}
1442 @cindex search path for @code{.include}
1443 @cindex @code{include} directive search path
1444 Use this option to add a @var{path} to the list of directories
1445 @command{@value{AS}} searches for files specified in @code{.include}
1446 directives (@pxref{Include,,@code{.include}}). You may use @option{-I} as
1447 many times as necessary to include a variety of paths. The current
1448 working directory is always searched first; after that, @command{@value{AS}}
1449 searches any @samp{-I} directories in the same order as they were
1450 specified (left to right) on the command line.
1453 @section Difference Tables: @option{-K}
1456 @ifclear DIFF-TBL-KLUGE
1457 On the @value{TARGET} family, this option is allowed, but has no effect. It is
1458 permitted for compatibility with the @sc{gnu} assembler on other platforms,
1459 where it can be used to warn when the assembler alters the machine code
1460 generated for @samp{.word} directives in difference tables. The @value{TARGET}
1461 family does not have the addressing limitations that sometimes lead to this
1462 alteration on other platforms.
1465 @ifset DIFF-TBL-KLUGE
1466 @cindex difference tables, warning
1467 @cindex warning for altered difference tables
1468 @command{@value{AS}} sometimes alters the code emitted for directives of the form
1469 @samp{.word @var{sym1}-@var{sym2}}; @pxref{Word,,@code{.word}}.
1470 You can use the @samp{-K} option if you want a warning issued when this
1475 @section Include Local Labels: @option{-L}
1478 @cindex local labels, retaining in output
1479 Labels beginning with @samp{L} (upper case only) are called @dfn{local
1480 labels}. @xref{Symbol Names}. Normally you do not see such labels when
1481 debugging, because they are intended for the use of programs (like
1482 compilers) that compose assembler programs, not for your notice.
1483 Normally both @command{@value{AS}} and @code{@value{LD}} discard such labels, so you do not
1484 normally debug with them.
1486 This option tells @command{@value{AS}} to retain those @samp{L@dots{}} symbols
1487 in the object file. Usually if you do this you also tell the linker
1488 @code{@value{LD}} to preserve symbols whose names begin with @samp{L}.
1490 By default, a local label is any label beginning with @samp{L}, but each
1491 target is allowed to redefine the local label prefix.
1493 On the HPPA local labels begin with @samp{L$}.
1497 @section Configuring listing output: @option{--listing}
1499 The listing feature of the assembler can be enabled via the command line switch
1500 @samp{-a} (@pxref{a}). This feature combines the input source file(s) with a
1501 hex dump of the corresponding locations in the output object file, and displays
1502 them as a listing file. The format of this listing can be controlled by pseudo
1503 ops inside the assembler source (@pxref{List} @pxref{Title} @pxref{Sbttl}
1504 @pxref{Psize} @pxref{Eject}) and also by the following switches:
1507 @item --listing-lhs-width=@samp{number}
1508 @kindex --listing-lhs-width
1509 @cindex Width of first line disassembly output
1510 Sets the maximum width, in words, of the first line of the hex byte dump. This
1511 dump appears on the left hand side of the listing output.
1513 @item --listing-lhs-width2=@samp{number}
1514 @kindex --listing-lhs-width2
1515 @cindex Width of continuation lines of disassembly output
1516 Sets the maximum width, in words, of any further lines of the hex byte dump for
1517 a given inut source line. If this value is not specified, it defaults to being
1518 the same as the value specified for @samp{--listing-lhs-width}. If neither
1519 switch is used the default is to one.
1521 @item --listing-rhs-width=@samp{number}
1522 @kindex --listing-rhs-width
1523 @cindex Width of source line output
1524 Sets the maximum width, in characters, of the source line that is displayed
1525 alongside the hex dump. The default value for this parameter is 100. The
1526 source line is displayed on the right hand side of the listing output.
1528 @item --listing-cont-lines=@samp{number}
1529 @kindex --listing-cont-lines
1530 @cindex Maximum number of continuation lines
1531 Sets the maximum number of continuation lines of hex dump that will be
1532 displayed for a given single line of source input. The default value is 4.
1536 @section Assemble in MRI Compatibility Mode: @option{-M}
1539 @cindex MRI compatibility mode
1540 The @option{-M} or @option{--mri} option selects MRI compatibility mode. This
1541 changes the syntax and pseudo-op handling of @command{@value{AS}} to make it
1542 compatible with the @code{ASM68K} or the @code{ASM960} (depending upon the
1543 configured target) assembler from Microtec Research. The exact nature of the
1544 MRI syntax will not be documented here; see the MRI manuals for more
1545 information. Note in particular that the handling of macros and macro
1546 arguments is somewhat different. The purpose of this option is to permit
1547 assembling existing MRI assembler code using @command{@value{AS}}.
1549 The MRI compatibility is not complete. Certain operations of the MRI assembler
1550 depend upon its object file format, and can not be supported using other object
1551 file formats. Supporting these would require enhancing each object file format
1552 individually. These are:
1555 @item global symbols in common section
1557 The m68k MRI assembler supports common sections which are merged by the linker.
1558 Other object file formats do not support this. @command{@value{AS}} handles
1559 common sections by treating them as a single common symbol. It permits local
1560 symbols to be defined within a common section, but it can not support global
1561 symbols, since it has no way to describe them.
1563 @item complex relocations
1565 The MRI assemblers support relocations against a negated section address, and
1566 relocations which combine the start addresses of two or more sections. These
1567 are not support by other object file formats.
1569 @item @code{END} pseudo-op specifying start address
1571 The MRI @code{END} pseudo-op permits the specification of a start address.
1572 This is not supported by other object file formats. The start address may
1573 instead be specified using the @option{-e} option to the linker, or in a linker
1576 @item @code{IDNT}, @code{.ident} and @code{NAME} pseudo-ops
1578 The MRI @code{IDNT}, @code{.ident} and @code{NAME} pseudo-ops assign a module
1579 name to the output file. This is not supported by other object file formats.
1581 @item @code{ORG} pseudo-op
1583 The m68k MRI @code{ORG} pseudo-op begins an absolute section at a given
1584 address. This differs from the usual @command{@value{AS}} @code{.org} pseudo-op,
1585 which changes the location within the current section. Absolute sections are
1586 not supported by other object file formats. The address of a section may be
1587 assigned within a linker script.
1590 There are some other features of the MRI assembler which are not supported by
1591 @command{@value{AS}}, typically either because they are difficult or because they
1592 seem of little consequence. Some of these may be supported in future releases.
1596 @item EBCDIC strings
1598 EBCDIC strings are not supported.
1600 @item packed binary coded decimal
1602 Packed binary coded decimal is not supported. This means that the @code{DC.P}
1603 and @code{DCB.P} pseudo-ops are not supported.
1605 @item @code{FEQU} pseudo-op
1607 The m68k @code{FEQU} pseudo-op is not supported.
1609 @item @code{NOOBJ} pseudo-op
1611 The m68k @code{NOOBJ} pseudo-op is not supported.
1613 @item @code{OPT} branch control options
1615 The m68k @code{OPT} branch control options---@code{B}, @code{BRS}, @code{BRB},
1616 @code{BRL}, and @code{BRW}---are ignored. @command{@value{AS}} automatically
1617 relaxes all branches, whether forward or backward, to an appropriate size, so
1618 these options serve no purpose.
1620 @item @code{OPT} list control options
1622 The following m68k @code{OPT} list control options are ignored: @code{C},
1623 @code{CEX}, @code{CL}, @code{CRE}, @code{E}, @code{G}, @code{I}, @code{M},
1624 @code{MEX}, @code{MC}, @code{MD}, @code{X}.
1626 @item other @code{OPT} options
1628 The following m68k @code{OPT} options are ignored: @code{NEST}, @code{O},
1629 @code{OLD}, @code{OP}, @code{P}, @code{PCO}, @code{PCR}, @code{PCS}, @code{R}.
1631 @item @code{OPT} @code{D} option is default
1633 The m68k @code{OPT} @code{D} option is the default, unlike the MRI assembler.
1634 @code{OPT NOD} may be used to turn it off.
1636 @item @code{XREF} pseudo-op.
1638 The m68k @code{XREF} pseudo-op is ignored.
1640 @item @code{.debug} pseudo-op
1642 The i960 @code{.debug} pseudo-op is not supported.
1644 @item @code{.extended} pseudo-op
1646 The i960 @code{.extended} pseudo-op is not supported.
1648 @item @code{.list} pseudo-op.
1650 The various options of the i960 @code{.list} pseudo-op are not supported.
1652 @item @code{.optimize} pseudo-op
1654 The i960 @code{.optimize} pseudo-op is not supported.
1656 @item @code{.output} pseudo-op
1658 The i960 @code{.output} pseudo-op is not supported.
1660 @item @code{.setreal} pseudo-op
1662 The i960 @code{.setreal} pseudo-op is not supported.
1667 @section Dependency tracking: @option{--MD}
1670 @cindex dependency tracking
1673 @command{@value{AS}} can generate a dependency file for the file it creates. This
1674 file consists of a single rule suitable for @code{make} describing the
1675 dependencies of the main source file.
1677 The rule is written to the file named in its argument.
1679 This feature is used in the automatic updating of makefiles.
1682 @section Name the Object File: @option{-o}
1685 @cindex naming object file
1686 @cindex object file name
1687 There is always one object file output when you run @command{@value{AS}}. By
1688 default it has the name
1691 @file{a.out} (or @file{b.out}, for Intel 960 targets only).
1705 You use this option (which takes exactly one filename) to give the
1706 object file a different name.
1708 Whatever the object file is called, @command{@value{AS}} overwrites any
1709 existing file of the same name.
1712 @section Join Data and Text Sections: @option{-R}
1715 @cindex data and text sections, joining
1716 @cindex text and data sections, joining
1717 @cindex joining text and data sections
1718 @cindex merging text and data sections
1719 @option{-R} tells @command{@value{AS}} to write the object file as if all
1720 data-section data lives in the text section. This is only done at
1721 the very last moment: your binary data are the same, but data
1722 section parts are relocated differently. The data section part of
1723 your object file is zero bytes long because all its bytes are
1724 appended to the text section. (@xref{Sections,,Sections and Relocation}.)
1726 When you specify @option{-R} it would be possible to generate shorter
1727 address displacements (because we do not have to cross between text and
1728 data section). We refrain from doing this simply for compatibility with
1729 older versions of @command{@value{AS}}. In future, @option{-R} may work this way.
1732 When @command{@value{AS}} is configured for COFF output,
1733 this option is only useful if you use sections named @samp{.text} and
1738 @option{-R} is not supported for any of the HPPA targets. Using
1739 @option{-R} generates a warning from @command{@value{AS}}.
1743 @section Display Assembly Statistics: @option{--statistics}
1745 @kindex --statistics
1746 @cindex statistics, about assembly
1747 @cindex time, total for assembly
1748 @cindex space used, maximum for assembly
1749 Use @samp{--statistics} to display two statistics about the resources used by
1750 @command{@value{AS}}: the maximum amount of space allocated during the assembly
1751 (in bytes), and the total execution time taken for the assembly (in @sc{cpu}
1754 @node traditional-format
1755 @section Compatible output: @option{--traditional-format}
1757 @kindex --traditional-format
1758 For some targets, the output of @command{@value{AS}} is different in some ways
1759 from the output of some existing assembler. This switch requests
1760 @command{@value{AS}} to use the traditional format instead.
1762 For example, it disables the exception frame optimizations which
1763 @command{@value{AS}} normally does by default on @code{@value{GCC}} output.
1766 @section Announce Version: @option{-v}
1770 @cindex assembler version
1771 @cindex version of assembler
1772 You can find out what version of as is running by including the
1773 option @samp{-v} (which you can also spell as @samp{-version}) on the
1777 @section Control Warnings: @option{-W}, @option{--warn}, @option{--no-warn}, @option{--fatal-warnings}
1779 @command{@value{AS}} should never give a warning or error message when
1780 assembling compiler output. But programs written by people often
1781 cause @command{@value{AS}} to give a warning that a particular assumption was
1782 made. All such warnings are directed to the standard error file.
1785 @kindex @samp{--no-warn}
1786 @cindex suppressing warnings
1787 @cindex warnings, suppressing
1788 If you use the @option{-W} and @option{--no-warn} options, no warnings are issued.
1789 This only affects the warning messages: it does not change any particular of
1790 how @command{@value{AS}} assembles your file. Errors, which stop the assembly,
1793 @kindex @samp{--fatal-warnings}
1794 @cindex errors, caused by warnings
1795 @cindex warnings, causing error
1796 If you use the @option{--fatal-warnings} option, @command{@value{AS}} considers
1797 files that generate warnings to be in error.
1799 @kindex @samp{--warn}
1800 @cindex warnings, switching on
1801 You can switch these options off again by specifying @option{--warn}, which
1802 causes warnings to be output as usual.
1805 @section Generate Object File in Spite of Errors: @option{-Z}
1806 @cindex object file, after errors
1807 @cindex errors, continuing after
1808 After an error message, @command{@value{AS}} normally produces no output. If for
1809 some reason you are interested in object file output even after
1810 @command{@value{AS}} gives an error message on your program, use the @samp{-Z}
1811 option. If there are any errors, @command{@value{AS}} continues anyways, and
1812 writes an object file after a final warning message of the form @samp{@var{n}
1813 errors, @var{m} warnings, generating bad object file.}
1818 @cindex machine-independent syntax
1819 @cindex syntax, machine-independent
1820 This chapter describes the machine-independent syntax allowed in a
1821 source file. @command{@value{AS}} syntax is similar to what many other
1822 assemblers use; it is inspired by the BSD 4.2
1827 assembler, except that @command{@value{AS}} does not assemble Vax bit-fields.
1831 * Preprocessing:: Preprocessing
1832 * Whitespace:: Whitespace
1833 * Comments:: Comments
1834 * Symbol Intro:: Symbols
1835 * Statements:: Statements
1836 * Constants:: Constants
1840 @section Preprocessing
1842 @cindex preprocessing
1843 The @command{@value{AS}} internal preprocessor:
1845 @cindex whitespace, removed by preprocessor
1847 adjusts and removes extra whitespace. It leaves one space or tab before
1848 the keywords on a line, and turns any other whitespace on the line into
1851 @cindex comments, removed by preprocessor
1853 removes all comments, replacing them with a single space, or an
1854 appropriate number of newlines.
1856 @cindex constants, converted by preprocessor
1858 converts character constants into the appropriate numeric values.
1861 It does not do macro processing, include file handling, or
1862 anything else you may get from your C compiler's preprocessor. You can
1863 do include file processing with the @code{.include} directive
1864 (@pxref{Include,,@code{.include}}). You can use the @sc{gnu} C compiler driver
1865 to get other ``CPP'' style preprocessing, by giving the input file a
1866 @samp{.S} suffix. @xref{Overall Options,, Options Controlling the Kind of
1867 Output, gcc.info, Using GNU CC}.
1869 Excess whitespace, comments, and character constants
1870 cannot be used in the portions of the input text that are not
1873 @cindex turning preprocessing on and off
1874 @cindex preprocessing, turning on and off
1877 If the first line of an input file is @code{#NO_APP} or if you use the
1878 @samp{-f} option, whitespace and comments are not removed from the input file.
1879 Within an input file, you can ask for whitespace and comment removal in
1880 specific portions of the by putting a line that says @code{#APP} before the
1881 text that may contain whitespace or comments, and putting a line that says
1882 @code{#NO_APP} after this text. This feature is mainly intend to support
1883 @code{asm} statements in compilers whose output is otherwise free of comments
1890 @dfn{Whitespace} is one or more blanks or tabs, in any order.
1891 Whitespace is used to separate symbols, and to make programs neater for
1892 people to read. Unless within character constants
1893 (@pxref{Characters,,Character Constants}), any whitespace means the same
1894 as exactly one space.
1900 There are two ways of rendering comments to @command{@value{AS}}. In both
1901 cases the comment is equivalent to one space.
1903 Anything from @samp{/*} through the next @samp{*/} is a comment.
1904 This means you may not nest these comments.
1908 The only way to include a newline ('\n') in a comment
1909 is to use this sort of comment.
1912 /* This sort of comment does not nest. */
1915 @cindex line comment character
1916 Anything from the @dfn{line comment} character to the next newline
1917 is considered a comment and is ignored. The line comment character is
1919 @samp{;} for the AMD 29K family;
1922 @samp{;} on the ARC;
1925 @samp{@@} on the ARM;
1928 @samp{;} for the H8/300 family;
1931 @samp{!} for the H8/500 family;
1934 @samp{;} for the HPPA;
1937 @samp{#} on the i386 and x86-64;
1940 @samp{#} on the i960;
1943 @samp{;} for the PDP-11;
1946 @samp{;} for picoJava;
1949 @samp{;} for Motorola PowerPC;
1952 @samp{!} for the Hitachi SH;
1955 @samp{!} on the SPARC;
1958 @samp{#} on the m32r;
1961 @samp{|} on the 680x0;
1964 @samp{#} on the 68HC11 and 68HC12;
1967 @samp{;} on the M880x0;
1970 @samp{#} on the Vax;
1973 @samp{!} for the Z8000;
1976 @samp{#} on the V850;
1978 see @ref{Machine Dependencies}. @refill
1979 @c FIXME What about i860?
1982 On some machines there are two different line comment characters. One
1983 character only begins a comment if it is the first non-whitespace character on
1984 a line, while the other always begins a comment.
1988 The V850 assembler also supports a double dash as starting a comment that
1989 extends to the end of the line.
1995 @cindex lines starting with @code{#}
1996 @cindex logical line numbers
1997 To be compatible with past assemblers, lines that begin with @samp{#} have a
1998 special interpretation. Following the @samp{#} should be an absolute
1999 expression (@pxref{Expressions}): the logical line number of the @emph{next}
2000 line. Then a string (@pxref{Strings,, Strings}) is allowed: if present it is a
2001 new logical file name. The rest of the line, if any, should be whitespace.
2003 If the first non-whitespace characters on the line are not numeric,
2004 the line is ignored. (Just like a comment.)
2007 # This is an ordinary comment.
2008 # 42-6 "new_file_name" # New logical file name
2009 # This is logical line # 36.
2011 This feature is deprecated, and may disappear from future versions
2012 of @command{@value{AS}}.
2017 @cindex characters used in symbols
2018 @ifclear SPECIAL-SYMS
2019 A @dfn{symbol} is one or more characters chosen from the set of all
2020 letters (both upper and lower case), digits and the three characters
2026 A @dfn{symbol} is one or more characters chosen from the set of all
2027 letters (both upper and lower case), digits and the three characters
2028 @samp{._$}. (Save that, on the H8/300 only, you may not use @samp{$} in
2034 On most machines, you can also use @code{$} in symbol names; exceptions
2035 are noted in @ref{Machine Dependencies}.
2037 No symbol may begin with a digit. Case is significant.
2038 There is no length limit: all characters are significant. Symbols are
2039 delimited by characters not in that set, or by the beginning of a file
2040 (since the source program must end with a newline, the end of a file is
2041 not a possible symbol delimiter). @xref{Symbols}.
2042 @cindex length of symbols
2047 @cindex statements, structure of
2048 @cindex line separator character
2049 @cindex statement separator character
2051 @ifclear abnormal-separator
2052 A @dfn{statement} ends at a newline character (@samp{\n}) or at a
2053 semicolon (@samp{;}). The newline or semicolon is considered part of
2054 the preceding statement. Newlines and semicolons within character
2055 constants are an exception: they do not end statements.
2057 @ifset abnormal-separator
2059 A @dfn{statement} ends at a newline character (@samp{\n}) or an ``at''
2060 sign (@samp{@@}). The newline or at sign is considered part of the
2061 preceding statement. Newlines and at signs within character constants
2062 are an exception: they do not end statements.
2065 A @dfn{statement} ends at a newline character (@samp{\n}) or an exclamation
2066 point (@samp{!}). The newline or exclamation point is considered part of the
2067 preceding statement. Newlines and exclamation points within character
2068 constants are an exception: they do not end statements.
2071 A @dfn{statement} ends at a newline character (@samp{\n}); or (for the
2072 H8/300) a dollar sign (@samp{$}); or (for the
2075 (@samp{;}). The newline or separator character is considered part of
2076 the preceding statement. Newlines and separators within character
2077 constants are an exception: they do not end statements.
2082 A @dfn{statement} ends at a newline character (@samp{\n}) or line
2083 separator character. (The line separator is usually @samp{;}, unless
2084 this conflicts with the comment character; @pxref{Machine Dependencies}.) The
2085 newline or separator character is considered part of the preceding
2086 statement. Newlines and separators within character constants are an
2087 exception: they do not end statements.
2090 @cindex newline, required at file end
2091 @cindex EOF, newline must precede
2092 It is an error to end any statement with end-of-file: the last
2093 character of any input file should be a newline.@refill
2095 An empty statement is allowed, and may include whitespace. It is ignored.
2097 @cindex instructions and directives
2098 @cindex directives and instructions
2099 @c "key symbol" is not used elsewhere in the document; seems pedantic to
2100 @c @defn{} it in that case, as was done previously... doc@cygnus.com,
2102 A statement begins with zero or more labels, optionally followed by a
2103 key symbol which determines what kind of statement it is. The key
2104 symbol determines the syntax of the rest of the statement. If the
2105 symbol begins with a dot @samp{.} then the statement is an assembler
2106 directive: typically valid for any computer. If the symbol begins with
2107 a letter the statement is an assembly language @dfn{instruction}: it
2108 assembles into a machine language instruction.
2110 Different versions of @command{@value{AS}} for different computers
2111 recognize different instructions. In fact, the same symbol may
2112 represent a different instruction in a different computer's assembly
2116 @cindex @code{:} (label)
2117 @cindex label (@code{:})
2118 A label is a symbol immediately followed by a colon (@code{:}).
2119 Whitespace before a label or after a colon is permitted, but you may not
2120 have whitespace between a label's symbol and its colon. @xref{Labels}.
2123 For HPPA targets, labels need not be immediately followed by a colon, but
2124 the definition of a label must begin in column zero. This also implies that
2125 only one label may be defined on each line.
2129 label: .directive followed by something
2130 another_label: # This is an empty statement.
2131 instruction operand_1, operand_2, @dots{}
2138 A constant is a number, written so that its value is known by
2139 inspection, without knowing any context. Like this:
2142 .byte 74, 0112, 092, 0x4A, 0X4a, 'J, '\J # All the same value.
2143 .ascii "Ring the bell\7" # A string constant.
2144 .octa 0x123456789abcdef0123456789ABCDEF0 # A bignum.
2145 .float 0f-314159265358979323846264338327\
2146 95028841971.693993751E-40 # - pi, a flonum.
2151 * Characters:: Character Constants
2152 * Numbers:: Number Constants
2156 @subsection Character Constants
2158 @cindex character constants
2159 @cindex constants, character
2160 There are two kinds of character constants. A @dfn{character} stands
2161 for one character in one byte and its value may be used in
2162 numeric expressions. String constants (properly called string
2163 @emph{literals}) are potentially many bytes and their values may not be
2164 used in arithmetic expressions.
2168 * Chars:: Characters
2172 @subsubsection Strings
2174 @cindex string constants
2175 @cindex constants, string
2176 A @dfn{string} is written between double-quotes. It may contain
2177 double-quotes or null characters. The way to get special characters
2178 into a string is to @dfn{escape} these characters: precede them with
2179 a backslash @samp{\} character. For example @samp{\\} represents
2180 one backslash: the first @code{\} is an escape which tells
2181 @command{@value{AS}} to interpret the second character literally as a backslash
2182 (which prevents @command{@value{AS}} from recognizing the second @code{\} as an
2183 escape character). The complete list of escapes follows.
2185 @cindex escape codes, character
2186 @cindex character escape codes
2189 @c Mnemonic for ACKnowledge; for ASCII this is octal code 007.
2191 @cindex @code{\b} (backspace character)
2192 @cindex backspace (@code{\b})
2194 Mnemonic for backspace; for ASCII this is octal code 010.
2197 @c Mnemonic for EOText; for ASCII this is octal code 004.
2199 @cindex @code{\f} (formfeed character)
2200 @cindex formfeed (@code{\f})
2202 Mnemonic for FormFeed; for ASCII this is octal code 014.
2204 @cindex @code{\n} (newline character)
2205 @cindex newline (@code{\n})
2207 Mnemonic for newline; for ASCII this is octal code 012.
2210 @c Mnemonic for prefix; for ASCII this is octal code 033, usually known as @code{escape}.
2212 @cindex @code{\r} (carriage return character)
2213 @cindex carriage return (@code{\r})
2215 Mnemonic for carriage-Return; for ASCII this is octal code 015.
2218 @c Mnemonic for space; for ASCII this is octal code 040. Included for compliance with
2219 @c other assemblers.
2221 @cindex @code{\t} (tab)
2222 @cindex tab (@code{\t})
2224 Mnemonic for horizontal Tab; for ASCII this is octal code 011.
2227 @c Mnemonic for Vertical tab; for ASCII this is octal code 013.
2228 @c @item \x @var{digit} @var{digit} @var{digit}
2229 @c A hexadecimal character code. The numeric code is 3 hexadecimal digits.
2231 @cindex @code{\@var{ddd}} (octal character code)
2232 @cindex octal character code (@code{\@var{ddd}})
2233 @item \ @var{digit} @var{digit} @var{digit}
2234 An octal character code. The numeric code is 3 octal digits.
2235 For compatibility with other Unix systems, 8 and 9 are accepted as digits:
2236 for example, @code{\008} has the value 010, and @code{\009} the value 011.
2238 @cindex @code{\@var{xd...}} (hex character code)
2239 @cindex hex character code (@code{\@var{xd...}})
2240 @item \@code{x} @var{hex-digits...}
2241 A hex character code. All trailing hex digits are combined. Either upper or
2242 lower case @code{x} works.
2244 @cindex @code{\\} (@samp{\} character)
2245 @cindex backslash (@code{\\})
2247 Represents one @samp{\} character.
2250 @c Represents one @samp{'} (accent acute) character.
2251 @c This is needed in single character literals
2252 @c (@xref{Characters,,Character Constants}.) to represent
2255 @cindex @code{\"} (doublequote character)
2256 @cindex doublequote (@code{\"})
2258 Represents one @samp{"} character. Needed in strings to represent
2259 this character, because an unescaped @samp{"} would end the string.
2261 @item \ @var{anything-else}
2262 Any other character when escaped by @kbd{\} gives a warning, but
2263 assembles as if the @samp{\} was not present. The idea is that if
2264 you used an escape sequence you clearly didn't want the literal
2265 interpretation of the following character. However @command{@value{AS}} has no
2266 other interpretation, so @command{@value{AS}} knows it is giving you the wrong
2267 code and warns you of the fact.
2270 Which characters are escapable, and what those escapes represent,
2271 varies widely among assemblers. The current set is what we think
2272 the BSD 4.2 assembler recognizes, and is a subset of what most C
2273 compilers recognize. If you are in doubt, do not use an escape
2277 @subsubsection Characters
2279 @cindex single character constant
2280 @cindex character, single
2281 @cindex constant, single character
2282 A single character may be written as a single quote immediately
2283 followed by that character. The same escapes apply to characters as
2284 to strings. So if you want to write the character backslash, you
2285 must write @kbd{'\\} where the first @code{\} escapes the second
2286 @code{\}. As you can see, the quote is an acute accent, not a
2287 grave accent. A newline
2289 @ifclear abnormal-separator
2290 (or semicolon @samp{;})
2292 @ifset abnormal-separator
2294 (or at sign @samp{@@})
2297 (or dollar sign @samp{$}, for the H8/300; or semicolon @samp{;} for the
2303 immediately following an acute accent is taken as a literal character
2304 and does not count as the end of a statement. The value of a character
2305 constant in a numeric expression is the machine's byte-wide code for
2306 that character. @command{@value{AS}} assumes your character code is ASCII:
2307 @kbd{'A} means 65, @kbd{'B} means 66, and so on. @refill
2310 @subsection Number Constants
2312 @cindex constants, number
2313 @cindex number constants
2314 @command{@value{AS}} distinguishes three kinds of numbers according to how they
2315 are stored in the target machine. @emph{Integers} are numbers that
2316 would fit into an @code{int} in the C language. @emph{Bignums} are
2317 integers, but they are stored in more than 32 bits. @emph{Flonums}
2318 are floating point numbers, described below.
2321 * Integers:: Integers
2326 * Bit Fields:: Bit Fields
2332 @subsubsection Integers
2334 @cindex constants, integer
2336 @cindex binary integers
2337 @cindex integers, binary
2338 A binary integer is @samp{0b} or @samp{0B} followed by zero or more of
2339 the binary digits @samp{01}.
2341 @cindex octal integers
2342 @cindex integers, octal
2343 An octal integer is @samp{0} followed by zero or more of the octal
2344 digits (@samp{01234567}).
2346 @cindex decimal integers
2347 @cindex integers, decimal
2348 A decimal integer starts with a non-zero digit followed by zero or
2349 more digits (@samp{0123456789}).
2351 @cindex hexadecimal integers
2352 @cindex integers, hexadecimal
2353 A hexadecimal integer is @samp{0x} or @samp{0X} followed by one or
2354 more hexadecimal digits chosen from @samp{0123456789abcdefABCDEF}.
2356 Integers have the usual values. To denote a negative integer, use
2357 the prefix operator @samp{-} discussed under expressions
2358 (@pxref{Prefix Ops,,Prefix Operators}).
2361 @subsubsection Bignums
2364 @cindex constants, bignum
2365 A @dfn{bignum} has the same syntax and semantics as an integer
2366 except that the number (or its negative) takes more than 32 bits to
2367 represent in binary. The distinction is made because in some places
2368 integers are permitted while bignums are not.
2371 @subsubsection Flonums
2373 @cindex floating point numbers
2374 @cindex constants, floating point
2376 @cindex precision, floating point
2377 A @dfn{flonum} represents a floating point number. The translation is
2378 indirect: a decimal floating point number from the text is converted by
2379 @command{@value{AS}} to a generic binary floating point number of more than
2380 sufficient precision. This generic floating point number is converted
2381 to a particular computer's floating point format (or formats) by a
2382 portion of @command{@value{AS}} specialized to that computer.
2384 A flonum is written by writing (in order)
2389 (@samp{0} is optional on the HPPA.)
2393 A letter, to tell @command{@value{AS}} the rest of the number is a flonum.
2395 @kbd{e} is recommended. Case is not important.
2397 @c FIXME: verify if flonum syntax really this vague for most cases
2398 (Any otherwise illegal letter works here, but that might be changed. Vax BSD
2399 4.2 assembler seems to allow any of @samp{defghDEFGH}.)
2402 On the H8/300, H8/500,
2404 and AMD 29K architectures, the letter must be
2405 one of the letters @samp{DFPRSX} (in upper or lower case).
2407 On the ARC, the letter must be one of the letters @samp{DFRS}
2408 (in upper or lower case).
2410 On the Intel 960 architecture, the letter must be
2411 one of the letters @samp{DFT} (in upper or lower case).
2413 On the HPPA architecture, the letter must be @samp{E} (upper case only).
2417 One of the letters @samp{DFPRSX} (in upper or lower case).
2420 One of the letters @samp{DFRS} (in upper or lower case).
2423 One of the letters @samp{DFPRSX} (in upper or lower case).
2426 The letter @samp{E} (upper case only).
2429 One of the letters @samp{DFT} (in upper or lower case).
2434 An optional sign: either @samp{+} or @samp{-}.
2437 An optional @dfn{integer part}: zero or more decimal digits.
2440 An optional @dfn{fractional part}: @samp{.} followed by zero
2441 or more decimal digits.
2444 An optional exponent, consisting of:
2448 An @samp{E} or @samp{e}.
2449 @c I can't find a config where "EXP_CHARS" is other than 'eE', but in
2450 @c principle this can perfectly well be different on different targets.
2452 Optional sign: either @samp{+} or @samp{-}.
2454 One or more decimal digits.
2459 At least one of the integer part or the fractional part must be
2460 present. The floating point number has the usual base-10 value.
2462 @command{@value{AS}} does all processing using integers. Flonums are computed
2463 independently of any floating point hardware in the computer running
2464 @command{@value{AS}}.
2468 @c Bit fields are written as a general facility but are also controlled
2469 @c by a conditional-compilation flag---which is as of now (21mar91)
2470 @c turned on only by the i960 config of GAS.
2472 @subsubsection Bit Fields
2475 @cindex constants, bit field
2476 You can also define numeric constants as @dfn{bit fields}.
2477 specify two numbers separated by a colon---
2479 @var{mask}:@var{value}
2482 @command{@value{AS}} applies a bitwise @sc{and} between @var{mask} and
2485 The resulting number is then packed
2487 @c this conditional paren in case bit fields turned on elsewhere than 960
2488 (in host-dependent byte order)
2490 into a field whose width depends on which assembler directive has the
2491 bit-field as its argument. Overflow (a result from the bitwise and
2492 requiring more binary digits to represent) is not an error; instead,
2493 more constants are generated, of the specified width, beginning with the
2494 least significant digits.@refill
2496 The directives @code{.byte}, @code{.hword}, @code{.int}, @code{.long},
2497 @code{.short}, and @code{.word} accept bit-field arguments.
2502 @chapter Sections and Relocation
2507 * Secs Background:: Background
2508 * Ld Sections:: Linker Sections
2509 * As Sections:: Assembler Internal Sections
2510 * Sub-Sections:: Sub-Sections
2514 @node Secs Background
2517 Roughly, a section is a range of addresses, with no gaps; all data
2518 ``in'' those addresses is treated the same for some particular purpose.
2519 For example there may be a ``read only'' section.
2521 @cindex linker, and assembler
2522 @cindex assembler, and linker
2523 The linker @code{@value{LD}} reads many object files (partial programs) and
2524 combines their contents to form a runnable program. When @command{@value{AS}}
2525 emits an object file, the partial program is assumed to start at address 0.
2526 @code{@value{LD}} assigns the final addresses for the partial program, so that
2527 different partial programs do not overlap. This is actually an
2528 oversimplification, but it suffices to explain how @command{@value{AS}} uses
2531 @code{@value{LD}} moves blocks of bytes of your program to their run-time
2532 addresses. These blocks slide to their run-time addresses as rigid
2533 units; their length does not change and neither does the order of bytes
2534 within them. Such a rigid unit is called a @emph{section}. Assigning
2535 run-time addresses to sections is called @dfn{relocation}. It includes
2536 the task of adjusting mentions of object-file addresses so they refer to
2537 the proper run-time addresses.
2539 For the H8/300 and H8/500,
2540 and for the Hitachi SH,
2541 @command{@value{AS}} pads sections if needed to
2542 ensure they end on a word (sixteen bit) boundary.
2545 @cindex standard assembler sections
2546 An object file written by @command{@value{AS}} has at least three sections, any
2547 of which may be empty. These are named @dfn{text}, @dfn{data} and
2552 When it generates COFF output,
2554 @command{@value{AS}} can also generate whatever other named sections you specify
2555 using the @samp{.section} directive (@pxref{Section,,@code{.section}}).
2556 If you do not use any directives that place output in the @samp{.text}
2557 or @samp{.data} sections, these sections still exist, but are empty.
2562 When @command{@value{AS}} generates SOM or ELF output for the HPPA,
2564 @command{@value{AS}} can also generate whatever other named sections you
2565 specify using the @samp{.space} and @samp{.subspace} directives. See
2566 @cite{HP9000 Series 800 Assembly Language Reference Manual}
2567 (HP 92432-90001) for details on the @samp{.space} and @samp{.subspace}
2568 assembler directives.
2571 Additionally, @command{@value{AS}} uses different names for the standard
2572 text, data, and bss sections when generating SOM output. Program text
2573 is placed into the @samp{$CODE$} section, data into @samp{$DATA$}, and
2574 BSS into @samp{$BSS$}.
2578 Within the object file, the text section starts at address @code{0}, the
2579 data section follows, and the bss section follows the data section.
2582 When generating either SOM or ELF output files on the HPPA, the text
2583 section starts at address @code{0}, the data section at address
2584 @code{0x4000000}, and the bss section follows the data section.
2587 To let @code{@value{LD}} know which data changes when the sections are
2588 relocated, and how to change that data, @command{@value{AS}} also writes to the
2589 object file details of the relocation needed. To perform relocation
2590 @code{@value{LD}} must know, each time an address in the object
2594 Where in the object file is the beginning of this reference to
2597 How long (in bytes) is this reference?
2599 Which section does the address refer to? What is the numeric value of
2601 (@var{address}) @minus{} (@var{start-address of section})?
2604 Is the reference to an address ``Program-Counter relative''?
2607 @cindex addresses, format of
2608 @cindex section-relative addressing
2609 In fact, every address @command{@value{AS}} ever uses is expressed as
2611 (@var{section}) + (@var{offset into section})
2614 Further, most expressions @command{@value{AS}} computes have this section-relative
2617 (For some object formats, such as SOM for the HPPA, some expressions are
2618 symbol-relative instead.)
2621 In this manual we use the notation @{@var{secname} @var{N}@} to mean ``offset
2622 @var{N} into section @var{secname}.''
2624 Apart from text, data and bss sections you need to know about the
2625 @dfn{absolute} section. When @code{@value{LD}} mixes partial programs,
2626 addresses in the absolute section remain unchanged. For example, address
2627 @code{@{absolute 0@}} is ``relocated'' to run-time address 0 by
2628 @code{@value{LD}}. Although the linker never arranges two partial programs'
2629 data sections with overlapping addresses after linking, @emph{by definition}
2630 their absolute sections must overlap. Address @code{@{absolute@ 239@}} in one
2631 part of a program is always the same address when the program is running as
2632 address @code{@{absolute@ 239@}} in any other part of the program.
2634 The idea of sections is extended to the @dfn{undefined} section. Any
2635 address whose section is unknown at assembly time is by definition
2636 rendered @{undefined @var{U}@}---where @var{U} is filled in later.
2637 Since numbers are always defined, the only way to generate an undefined
2638 address is to mention an undefined symbol. A reference to a named
2639 common block would be such a symbol: its value is unknown at assembly
2640 time so it has section @emph{undefined}.
2642 By analogy the word @emph{section} is used to describe groups of sections in
2643 the linked program. @code{@value{LD}} puts all partial programs' text
2644 sections in contiguous addresses in the linked program. It is
2645 customary to refer to the @emph{text section} of a program, meaning all
2646 the addresses of all partial programs' text sections. Likewise for
2647 data and bss sections.
2649 Some sections are manipulated by @code{@value{LD}}; others are invented for
2650 use of @command{@value{AS}} and have no meaning except during assembly.
2653 @section Linker Sections
2654 @code{@value{LD}} deals with just four kinds of sections, summarized below.
2659 @cindex named sections
2660 @cindex sections, named
2661 @item named sections
2664 @cindex text section
2665 @cindex data section
2669 These sections hold your program. @command{@value{AS}} and @code{@value{LD}} treat them as
2670 separate but equal sections. Anything you can say of one section is
2673 When the program is running, however, it is
2674 customary for the text section to be unalterable. The
2675 text section is often shared among processes: it contains
2676 instructions, constants and the like. The data section of a running
2677 program is usually alterable: for example, C variables would be stored
2678 in the data section.
2683 This section contains zeroed bytes when your program begins running. It
2684 is used to hold uninitialized variables or common storage. The length of
2685 each partial program's bss section is important, but because it starts
2686 out containing zeroed bytes there is no need to store explicit zero
2687 bytes in the object file. The bss section was invented to eliminate
2688 those explicit zeros from object files.
2690 @cindex absolute section
2691 @item absolute section
2692 Address 0 of this section is always ``relocated'' to runtime address 0.
2693 This is useful if you want to refer to an address that @code{@value{LD}} must
2694 not change when relocating. In this sense we speak of absolute
2695 addresses being ``unrelocatable'': they do not change during relocation.
2697 @cindex undefined section
2698 @item undefined section
2699 This ``section'' is a catch-all for address references to objects not in
2700 the preceding sections.
2701 @c FIXME: ref to some other doc on obj-file formats could go here.
2704 @cindex relocation example
2705 An idealized example of three relocatable sections follows.
2707 The example uses the traditional section names @samp{.text} and @samp{.data}.
2709 Memory addresses are on the horizontal axis.
2713 @c END TEXI2ROFF-KILL
2716 partial program # 1: |ttttt|dddd|00|
2723 partial program # 2: |TTT|DDD|000|
2726 +--+---+-----+--+----+---+-----+~~
2727 linked program: | |TTT|ttttt| |dddd|DDD|00000|
2728 +--+---+-----+--+----+---+-----+~~
2730 addresses: 0 @dots{}
2737 \line{\it Partial program \#1: \hfil}
2738 \line{\ibox{2.5cm}{\tt text}\ibox{2cm}{\tt data}\ibox{1cm}{\tt bss}\hfil}
2739 \line{\boxit{2.5cm}{\tt ttttt}\boxit{2cm}{\tt dddd}\boxit{1cm}{\tt 00}\hfil}
2741 \line{\it Partial program \#2: \hfil}
2742 \line{\ibox{1cm}{\tt text}\ibox{1.5cm}{\tt data}\ibox{1cm}{\tt bss}\hfil}
2743 \line{\boxit{1cm}{\tt TTT}\boxit{1.5cm}{\tt DDDD}\boxit{1cm}{\tt 000}\hfil}
2745 \line{\it linked program: \hfil}
2746 \line{\ibox{.5cm}{}\ibox{1cm}{\tt text}\ibox{2.5cm}{}\ibox{.75cm}{}\ibox{2cm}{\tt data}\ibox{1.5cm}{}\ibox{2cm}{\tt bss}\hfil}
2747 \line{\boxit{.5cm}{}\boxit{1cm}{\tt TTT}\boxit{2.5cm}{\tt
2748 ttttt}\boxit{.75cm}{}\boxit{2cm}{\tt dddd}\boxit{1.5cm}{\tt
2749 DDDD}\boxit{2cm}{\tt 00000}\ \dots\hfil}
2751 \line{\it addresses: \hfil}
2755 @c END TEXI2ROFF-KILL
2758 @section Assembler Internal Sections
2760 @cindex internal assembler sections
2761 @cindex sections in messages, internal
2762 These sections are meant only for the internal use of @command{@value{AS}}. They
2763 have no meaning at run-time. You do not really need to know about these
2764 sections for most purposes; but they can be mentioned in @command{@value{AS}}
2765 warning messages, so it might be helpful to have an idea of their
2766 meanings to @command{@value{AS}}. These sections are used to permit the
2767 value of every expression in your assembly language program to be a
2768 section-relative address.
2771 @cindex assembler internal logic error
2772 @item ASSEMBLER-INTERNAL-LOGIC-ERROR!
2773 An internal assembler logic error has been found. This means there is a
2774 bug in the assembler.
2776 @cindex expr (internal section)
2778 The assembler stores complex expression internally as combinations of
2779 symbols. When it needs to represent an expression as a symbol, it puts
2780 it in the expr section.
2782 @c FIXME item transfer[t] vector preload
2783 @c FIXME item transfer[t] vector postload
2784 @c FIXME item register
2788 @section Sub-Sections
2790 @cindex numbered subsections
2791 @cindex grouping data
2797 fall into two sections: text and data.
2799 You may have separate groups of
2801 data in named sections
2805 data in named sections
2811 that you want to end up near to each other in the object file, even though they
2812 are not contiguous in the assembler source. @command{@value{AS}} allows you to
2813 use @dfn{subsections} for this purpose. Within each section, there can be
2814 numbered subsections with values from 0 to 8192. Objects assembled into the
2815 same subsection go into the object file together with other objects in the same
2816 subsection. For example, a compiler might want to store constants in the text
2817 section, but might not want to have them interspersed with the program being
2818 assembled. In this case, the compiler could issue a @samp{.text 0} before each
2819 section of code being output, and a @samp{.text 1} before each group of
2820 constants being output.
2822 Subsections are optional. If you do not use subsections, everything
2823 goes in subsection number zero.
2826 Each subsection is zero-padded up to a multiple of four bytes.
2827 (Subsections may be padded a different amount on different flavors
2828 of @command{@value{AS}}.)
2832 On the H8/300 and H8/500 platforms, each subsection is zero-padded to a word
2833 boundary (two bytes).
2834 The same is true on the Hitachi SH.
2837 @c FIXME section padding (alignment)?
2838 @c Rich Pixley says padding here depends on target obj code format; that
2839 @c doesn't seem particularly useful to say without further elaboration,
2840 @c so for now I say nothing about it. If this is a generic BFD issue,
2841 @c these paragraphs might need to vanish from this manual, and be
2842 @c discussed in BFD chapter of binutils (or some such).
2845 On the AMD 29K family, no particular padding is added to section or
2846 subsection sizes; @value{AS} forces no alignment on this platform.
2850 Subsections appear in your object file in numeric order, lowest numbered
2851 to highest. (All this to be compatible with other people's assemblers.)
2852 The object file contains no representation of subsections; @code{@value{LD}} and
2853 other programs that manipulate object files see no trace of them.
2854 They just see all your text subsections as a text section, and all your
2855 data subsections as a data section.
2857 To specify which subsection you want subsequent statements assembled
2858 into, use a numeric argument to specify it, in a @samp{.text
2859 @var{expression}} or a @samp{.data @var{expression}} statement.
2862 When generating COFF output, you
2867 can also use an extra subsection
2868 argument with arbitrary named sections: @samp{.section @var{name},
2871 @var{Expression} should be an absolute expression.
2872 (@xref{Expressions}.) If you just say @samp{.text} then @samp{.text 0}
2873 is assumed. Likewise @samp{.data} means @samp{.data 0}. Assembly
2874 begins in @code{text 0}. For instance:
2876 .text 0 # The default subsection is text 0 anyway.
2877 .ascii "This lives in the first text subsection. *"
2879 .ascii "But this lives in the second text subsection."
2881 .ascii "This lives in the data section,"
2882 .ascii "in the first data subsection."
2884 .ascii "This lives in the first text section,"
2885 .ascii "immediately following the asterisk (*)."
2888 Each section has a @dfn{location counter} incremented by one for every byte
2889 assembled into that section. Because subsections are merely a convenience
2890 restricted to @command{@value{AS}} there is no concept of a subsection location
2891 counter. There is no way to directly manipulate a location counter---but the
2892 @code{.align} directive changes it, and any label definition captures its
2893 current value. The location counter of the section where statements are being
2894 assembled is said to be the @dfn{active} location counter.
2897 @section bss Section
2900 @cindex common variable storage
2901 The bss section is used for local common variable storage.
2902 You may allocate address space in the bss section, but you may
2903 not dictate data to load into it before your program executes. When
2904 your program starts running, all the contents of the bss
2905 section are zeroed bytes.
2907 The @code{.lcomm} pseudo-op defines a symbol in the bss section; see
2908 @ref{Lcomm,,@code{.lcomm}}.
2910 The @code{.comm} pseudo-op may be used to declare a common symbol, which is
2911 another form of uninitialized symbol; see @xref{Comm,,@code{.comm}}.
2914 When assembling for a target which supports multiple sections, such as ELF or
2915 COFF, you may switch into the @code{.bss} section and define symbols as usual;
2916 see @ref{Section,,@code{.section}}. You may only assemble zero values into the
2917 section. Typically the section will only contain symbol definitions and
2918 @code{.skip} directives (@pxref{Skip,,@code{.skip}}).
2925 Symbols are a central concept: the programmer uses symbols to name
2926 things, the linker uses symbols to link, and the debugger uses symbols
2930 @cindex debuggers, and symbol order
2931 @emph{Warning:} @command{@value{AS}} does not place symbols in the object file in
2932 the same order they were declared. This may break some debuggers.
2937 * Setting Symbols:: Giving Symbols Other Values
2938 * Symbol Names:: Symbol Names
2939 * Dot:: The Special Dot Symbol
2940 * Symbol Attributes:: Symbol Attributes
2947 A @dfn{label} is written as a symbol immediately followed by a colon
2948 @samp{:}. The symbol then represents the current value of the
2949 active location counter, and is, for example, a suitable instruction
2950 operand. You are warned if you use the same symbol to represent two
2951 different locations: the first definition overrides any other
2955 On the HPPA, the usual form for a label need not be immediately followed by a
2956 colon, but instead must start in column zero. Only one label may be defined on
2957 a single line. To work around this, the HPPA version of @command{@value{AS}} also
2958 provides a special directive @code{.label} for defining labels more flexibly.
2961 @node Setting Symbols
2962 @section Giving Symbols Other Values
2964 @cindex assigning values to symbols
2965 @cindex symbol values, assigning
2966 A symbol can be given an arbitrary value by writing a symbol, followed
2967 by an equals sign @samp{=}, followed by an expression
2968 (@pxref{Expressions}). This is equivalent to using the @code{.set}
2969 directive. @xref{Set,,@code{.set}}.
2972 @section Symbol Names
2974 @cindex symbol names
2975 @cindex names, symbol
2976 @ifclear SPECIAL-SYMS
2977 Symbol names begin with a letter or with one of @samp{._}. On most
2978 machines, you can also use @code{$} in symbol names; exceptions are
2979 noted in @ref{Machine Dependencies}. That character may be followed by any
2980 string of digits, letters, dollar signs (unless otherwise noted in
2981 @ref{Machine Dependencies}), and underscores.
2984 For the AMD 29K family, @samp{?} is also allowed in the
2985 body of a symbol name, though not at its beginning.
2990 Symbol names begin with a letter or with one of @samp{._}. On the
2992 H8/500, you can also use @code{$} in symbol names. That character may
2993 be followed by any string of digits, letters, dollar signs (save on the
2994 H8/300), and underscores.
2998 Case of letters is significant: @code{foo} is a different symbol name
3001 Each symbol has exactly one name. Each name in an assembly language program
3002 refers to exactly one symbol. You may use that symbol name any number of times
3005 @subheading Local Symbol Names
3007 @cindex local symbol names
3008 @cindex symbol names, local
3009 @cindex temporary symbol names
3010 @cindex symbol names, temporary
3011 Local symbols help compilers and programmers use names temporarily.
3012 They create symbols which are guaranteed to be unique over the entire scope of
3013 the input source code and which can be referred to by a simple notation.
3014 To define a local symbol, write a label of the form @samp{@b{N}:} (where @b{N}
3015 represents any positive integer). To refer to the most recent previous
3016 definition of that symbol write @samp{@b{N}b}, using the same number as when
3017 you defined the label. To refer to the next definition of a local label, write
3018 @samp{@b{N}f}--- The @samp{b} stands for``backwards'' and the @samp{f} stands
3021 There is no restriction on how you can use these labels, and you can reuse them
3022 too. So that it is possible to repeatedly define the same local label (using
3023 the same number @samp{@b{N}}), although you can only refer to the most recently
3024 defined local label of that number (for a backwards reference) or the next
3025 definition of a specific local label for a forward reference. It is also worth
3026 noting that the first 10 local labels (@samp{@b{0:}}@dots{}@samp{@b{9:}}) are
3027 implemented in a slightly more efficient manner than the others.
3038 Which is the equivalent of:
3041 label_1: branch label_3
3042 label_2: branch label_1
3043 label_3: branch label_4
3044 label_4: branch label_3
3047 Local symbol names are only a notational device. They are immediately
3048 transformed into more conventional symbol names before the assembler uses them.
3049 The symbol names stored in the symbol table, appearing in error messages and
3050 optionally emitted to the object file. The names are constructed using these
3055 All local labels begin with @samp{L}. Normally both @command{@value{AS}} and
3056 @code{@value{LD}} forget symbols that start with @samp{L}. These labels are
3057 used for symbols you are never intended to see. If you use the
3058 @samp{-L} option then @command{@value{AS}} retains these symbols in the
3059 object file. If you also instruct @code{@value{LD}} to retain these symbols,
3060 you may use them in debugging.
3063 This is the number that was used in the local label definition. So if the
3064 label is written @samp{55:} then the number is @samp{55}.
3067 This unusual character is included so you do not accidentally invent a symbol
3068 of the same name. The character has ASCII value of @samp{\002} (control-B).
3070 @item @emph{ordinal number}
3071 This is a serial number to keep the labels distinct. The first definition of
3072 @samp{0:} gets the number @samp{1}. The 15th definition of @samp{0:} gets the
3073 number @samp{15}, and so on. Likewise the first definition of @samp{1:} gets
3074 the number @samp{1} and its 15th defintion gets @samp{15} as well.
3077 So for example, the first @code{1:} is named @code{L1@kbd{C-B}1}, the 44th
3078 @code{3:} is named @code{L3@kbd{C-B}44}.
3080 @subheading Dollar Local Labels
3081 @cindex dollar local symbols
3083 @code{@value{AS}} also supports an even more local form of local labels called
3084 dollar labels. These labels go out of scope (ie they become undefined) as soon
3085 as a non-local label is defined. Thus they remain valid for only a small
3086 region of the input source code. Normal local labels, by contrast, remain in
3087 scope for the entire file, or until they are redefined by another occurrence of
3088 the same local label.
3090 Dollar labels are defined in exactly the same way as ordinary local labels,
3091 except that instead of being terminated by a colon, they are terminated by a
3092 dollar sign. eg @samp{@b{55$}}.
3094 They can also be distinguished from ordinary local labels by their transformed
3095 name which uses ASCII character @samp{\001} (control-A) as the magic character
3096 to distinguish them from ordinary labels. Thus the 5th defintion of @samp{6$}
3097 is named @samp{L6@kbd{C-A}5}.
3100 @section The Special Dot Symbol
3102 @cindex dot (symbol)
3103 @cindex @code{.} (symbol)
3104 @cindex current address
3105 @cindex location counter
3106 The special symbol @samp{.} refers to the current address that
3107 @command{@value{AS}} is assembling into. Thus, the expression @samp{melvin:
3108 .long .} defines @code{melvin} to contain its own address.
3109 Assigning a value to @code{.} is treated the same as a @code{.org}
3110 directive. Thus, the expression @samp{.=.+4} is the same as saying
3111 @ifclear no-space-dir
3120 @node Symbol Attributes
3121 @section Symbol Attributes
3123 @cindex symbol attributes
3124 @cindex attributes, symbol
3125 Every symbol has, as well as its name, the attributes ``Value'' and
3126 ``Type''. Depending on output format, symbols can also have auxiliary
3129 The detailed definitions are in @file{a.out.h}.
3132 If you use a symbol without defining it, @command{@value{AS}} assumes zero for
3133 all these attributes, and probably won't warn you. This makes the
3134 symbol an externally defined symbol, which is generally what you
3138 * Symbol Value:: Value
3139 * Symbol Type:: Type
3142 * a.out Symbols:: Symbol Attributes: @code{a.out}
3146 * a.out Symbols:: Symbol Attributes: @code{a.out}
3149 * a.out Symbols:: Symbol Attributes: @code{a.out}, @code{b.out}
3154 * COFF Symbols:: Symbol Attributes for COFF
3157 * SOM Symbols:: Symbol Attributes for SOM
3164 @cindex value of a symbol
3165 @cindex symbol value
3166 The value of a symbol is (usually) 32 bits. For a symbol which labels a
3167 location in the text, data, bss or absolute sections the value is the
3168 number of addresses from the start of that section to the label.
3169 Naturally for text, data and bss sections the value of a symbol changes
3170 as @code{@value{LD}} changes section base addresses during linking. Absolute
3171 symbols' values do not change during linking: that is why they are
3174 The value of an undefined symbol is treated in a special way. If it is
3175 0 then the symbol is not defined in this assembler source file, and
3176 @code{@value{LD}} tries to determine its value from other files linked into the
3177 same program. You make this kind of symbol simply by mentioning a symbol
3178 name without defining it. A non-zero value represents a @code{.comm}
3179 common declaration. The value is how much common storage to reserve, in
3180 bytes (addresses). The symbol refers to the first address of the
3186 @cindex type of a symbol
3188 The type attribute of a symbol contains relocation (section)
3189 information, any flag settings indicating that a symbol is external, and
3190 (optionally), other information for linkers and debuggers. The exact
3191 format depends on the object-code output format in use.
3196 @c The following avoids a "widow" subsection title. @group would be
3197 @c better if it were available outside examples.
3200 @subsection Symbol Attributes: @code{a.out}, @code{b.out}
3202 @cindex @code{b.out} symbol attributes
3203 @cindex symbol attributes, @code{b.out}
3204 These symbol attributes appear only when @command{@value{AS}} is configured for
3205 one of the Berkeley-descended object output formats---@code{a.out} or
3211 @subsection Symbol Attributes: @code{a.out}
3213 @cindex @code{a.out} symbol attributes
3214 @cindex symbol attributes, @code{a.out}
3220 @subsection Symbol Attributes: @code{a.out}
3222 @cindex @code{a.out} symbol attributes
3223 @cindex symbol attributes, @code{a.out}
3227 * Symbol Desc:: Descriptor
3228 * Symbol Other:: Other
3232 @subsubsection Descriptor
3234 @cindex descriptor, of @code{a.out} symbol
3235 This is an arbitrary 16-bit value. You may establish a symbol's
3236 descriptor value by using a @code{.desc} statement
3237 (@pxref{Desc,,@code{.desc}}). A descriptor value means nothing to
3238 @command{@value{AS}}.
3241 @subsubsection Other
3243 @cindex other attribute, of @code{a.out} symbol
3244 This is an arbitrary 8-bit value. It means nothing to @command{@value{AS}}.
3249 @subsection Symbol Attributes for COFF
3251 @cindex COFF symbol attributes
3252 @cindex symbol attributes, COFF
3254 The COFF format supports a multitude of auxiliary symbol attributes;
3255 like the primary symbol attributes, they are set between @code{.def} and
3256 @code{.endef} directives.
3258 @subsubsection Primary Attributes
3260 @cindex primary attributes, COFF symbols
3261 The symbol name is set with @code{.def}; the value and type,
3262 respectively, with @code{.val} and @code{.type}.
3264 @subsubsection Auxiliary Attributes
3266 @cindex auxiliary attributes, COFF symbols
3267 The @command{@value{AS}} directives @code{.dim}, @code{.line}, @code{.scl},
3268 @code{.size}, and @code{.tag} can generate auxiliary symbol table
3269 information for COFF.
3274 @subsection Symbol Attributes for SOM
3276 @cindex SOM symbol attributes
3277 @cindex symbol attributes, SOM
3279 The SOM format for the HPPA supports a multitude of symbol attributes set with
3280 the @code{.EXPORT} and @code{.IMPORT} directives.
3282 The attributes are described in @cite{HP9000 Series 800 Assembly
3283 Language Reference Manual} (HP 92432-90001) under the @code{IMPORT} and
3284 @code{EXPORT} assembler directive documentation.
3288 @chapter Expressions
3292 @cindex numeric values
3293 An @dfn{expression} specifies an address or numeric value.
3294 Whitespace may precede and/or follow an expression.
3296 The result of an expression must be an absolute number, or else an offset into
3297 a particular section. If an expression is not absolute, and there is not
3298 enough information when @command{@value{AS}} sees the expression to know its
3299 section, a second pass over the source program might be necessary to interpret
3300 the expression---but the second pass is currently not implemented.
3301 @command{@value{AS}} aborts with an error message in this situation.
3304 * Empty Exprs:: Empty Expressions
3305 * Integer Exprs:: Integer Expressions
3309 @section Empty Expressions
3311 @cindex empty expressions
3312 @cindex expressions, empty
3313 An empty expression has no value: it is just whitespace or null.
3314 Wherever an absolute expression is required, you may omit the
3315 expression, and @command{@value{AS}} assumes a value of (absolute) 0. This
3316 is compatible with other assemblers.
3319 @section Integer Expressions
3321 @cindex integer expressions
3322 @cindex expressions, integer
3323 An @dfn{integer expression} is one or more @emph{arguments} delimited
3324 by @emph{operators}.
3327 * Arguments:: Arguments
3328 * Operators:: Operators
3329 * Prefix Ops:: Prefix Operators
3330 * Infix Ops:: Infix Operators
3334 @subsection Arguments
3336 @cindex expression arguments
3337 @cindex arguments in expressions
3338 @cindex operands in expressions
3339 @cindex arithmetic operands
3340 @dfn{Arguments} are symbols, numbers or subexpressions. In other
3341 contexts arguments are sometimes called ``arithmetic operands''. In
3342 this manual, to avoid confusing them with the ``instruction operands'' of
3343 the machine language, we use the term ``argument'' to refer to parts of
3344 expressions only, reserving the word ``operand'' to refer only to machine
3345 instruction operands.
3347 Symbols are evaluated to yield @{@var{section} @var{NNN}@} where
3348 @var{section} is one of text, data, bss, absolute,
3349 or undefined. @var{NNN} is a signed, 2's complement 32 bit
3352 Numbers are usually integers.
3354 A number can be a flonum or bignum. In this case, you are warned
3355 that only the low order 32 bits are used, and @command{@value{AS}} pretends
3356 these 32 bits are an integer. You may write integer-manipulating
3357 instructions that act on exotic constants, compatible with other
3360 @cindex subexpressions
3361 Subexpressions are a left parenthesis @samp{(} followed by an integer
3362 expression, followed by a right parenthesis @samp{)}; or a prefix
3363 operator followed by an argument.
3366 @subsection Operators
3368 @cindex operators, in expressions
3369 @cindex arithmetic functions
3370 @cindex functions, in expressions
3371 @dfn{Operators} are arithmetic functions, like @code{+} or @code{%}. Prefix
3372 operators are followed by an argument. Infix operators appear
3373 between their arguments. Operators may be preceded and/or followed by
3377 @subsection Prefix Operator
3379 @cindex prefix operators
3380 @command{@value{AS}} has the following @dfn{prefix operators}. They each take
3381 one argument, which must be absolute.
3383 @c the tex/end tex stuff surrounding this small table is meant to make
3384 @c it align, on the printed page, with the similar table in the next
3385 @c section (which is inside an enumerate).
3387 \global\advance\leftskip by \itemindent
3392 @dfn{Negation}. Two's complement negation.
3394 @dfn{Complementation}. Bitwise not.
3398 \global\advance\leftskip by -\itemindent
3402 @subsection Infix Operators
3404 @cindex infix operators
3405 @cindex operators, permitted arguments
3406 @dfn{Infix operators} take two arguments, one on either side. Operators
3407 have precedence, but operations with equal precedence are performed left
3408 to right. Apart from @code{+} or @option{-}, both arguments must be
3409 absolute, and the result is absolute.
3412 @cindex operator precedence
3413 @cindex precedence of operators
3420 @dfn{Multiplication}.
3423 @dfn{Division}. Truncation is the same as the C operator @samp{/}
3430 @dfn{Shift Left}. Same as the C operator @samp{<<}.
3434 @dfn{Shift Right}. Same as the C operator @samp{>>}.
3438 Intermediate precedence
3443 @dfn{Bitwise Inclusive Or}.
3449 @dfn{Bitwise Exclusive Or}.
3452 @dfn{Bitwise Or Not}.
3459 @cindex addition, permitted arguments
3460 @cindex plus, permitted arguments
3461 @cindex arguments for addition
3463 @dfn{Addition}. If either argument is absolute, the result has the section of
3464 the other argument. You may not add together arguments from different
3467 @cindex subtraction, permitted arguments
3468 @cindex minus, permitted arguments
3469 @cindex arguments for subtraction
3471 @dfn{Subtraction}. If the right argument is absolute, the
3472 result has the section of the left argument.
3473 If both arguments are in the same section, the result is absolute.
3474 You may not subtract arguments from different sections.
3475 @c FIXME is there still something useful to say about undefined - undefined ?
3477 @cindex comparison expressions
3478 @cindex expressions, comparison
3482 @dfn{Is Not Equal To}
3486 @dfn{Is Greater Than}
3488 @dfn{Is Greater Than Or Equal To}
3490 @dfn{Is Less Than Or Equal To}
3492 The comparison operators can be used as infix operators. A true results has a
3493 value of -1 whereas a false result has a value of 0. Note, these operators
3494 perform signed comparisons.
3497 @item Lowest Precedence
3506 These two logical operations can be used to combine the results of sub
3507 expressions. Note, unlike the comparison operators a true result returns a
3508 value of 1 but a false results does still return 0. Also note that the logical
3509 or operator has a slightly lower precedence than logical and.
3514 In short, it's only meaningful to add or subtract the @emph{offsets} in an
3515 address; you can only have a defined section in one of the two arguments.
3518 @chapter Assembler Directives
3520 @cindex directives, machine independent
3521 @cindex pseudo-ops, machine independent
3522 @cindex machine independent directives
3523 All assembler directives have names that begin with a period (@samp{.}).
3524 The rest of the name is letters, usually in lower case.
3526 This chapter discusses directives that are available regardless of the
3527 target machine configuration for the @sc{gnu} assembler.
3529 Some machine configurations provide additional directives.
3530 @xref{Machine Dependencies}.
3533 @ifset machine-directives
3534 @xref{Machine Dependencies} for additional directives.
3539 * Abort:: @code{.abort}
3541 * ABORT:: @code{.ABORT}
3544 * Align:: @code{.align @var{abs-expr} , @var{abs-expr}}
3545 * Ascii:: @code{.ascii "@var{string}"}@dots{}
3546 * Asciz:: @code{.asciz "@var{string}"}@dots{}
3547 * Balign:: @code{.balign @var{abs-expr} , @var{abs-expr}}
3548 * Byte:: @code{.byte @var{expressions}}
3549 * Comm:: @code{.comm @var{symbol} , @var{length} }
3550 * Data:: @code{.data @var{subsection}}
3552 * Def:: @code{.def @var{name}}
3555 * Desc:: @code{.desc @var{symbol}, @var{abs-expression}}
3561 * Double:: @code{.double @var{flonums}}
3562 * Eject:: @code{.eject}
3563 * Else:: @code{.else}
3564 * Elseif:: @code{.elseif}
3567 * Endef:: @code{.endef}
3570 * Endfunc:: @code{.endfunc}
3571 * Endif:: @code{.endif}
3572 * Equ:: @code{.equ @var{symbol}, @var{expression}}
3573 * Equiv:: @code{.equiv @var{symbol}, @var{expression}}
3575 * Exitm:: @code{.exitm}
3576 * Extern:: @code{.extern}
3577 * Fail:: @code{.fail}
3578 @ifclear no-file-dir
3579 * File:: @code{.file @var{string}}
3582 * Fill:: @code{.fill @var{repeat} , @var{size} , @var{value}}
3583 * Float:: @code{.float @var{flonums}}
3584 * Func:: @code{.func}
3585 * Global:: @code{.global @var{symbol}}, @code{.globl @var{symbol}}
3587 * Hidden:: @code{.hidden @var{names}}
3590 * hword:: @code{.hword @var{expressions}}
3591 * Ident:: @code{.ident}
3592 * If:: @code{.if @var{absolute expression}}
3593 * Incbin:: @code{.incbin "@var{file}"[,@var{skip}[,@var{count}]]}
3594 * Include:: @code{.include "@var{file}"}
3595 * Int:: @code{.int @var{expressions}}
3597 * Internal:: @code{.internal @var{names}}
3600 * Irp:: @code{.irp @var{symbol},@var{values}}@dots{}
3601 * Irpc:: @code{.irpc @var{symbol},@var{values}}@dots{}
3602 * Lcomm:: @code{.lcomm @var{symbol} , @var{length}}
3603 * Lflags:: @code{.lflags}
3604 @ifclear no-line-dir
3605 * Line:: @code{.line @var{line-number}}
3608 * Ln:: @code{.ln @var{line-number}}
3609 * Linkonce:: @code{.linkonce [@var{type}]}
3610 * List:: @code{.list}
3611 * Long:: @code{.long @var{expressions}}
3613 * Lsym:: @code{.lsym @var{symbol}, @var{expression}}
3616 * Macro:: @code{.macro @var{name} @var{args}}@dots{}
3617 * MRI:: @code{.mri @var{val}}
3618 * Nolist:: @code{.nolist}
3619 * Octa:: @code{.octa @var{bignums}}
3620 * Org:: @code{.org @var{new-lc} , @var{fill}}
3621 * P2align:: @code{.p2align @var{abs-expr} , @var{abs-expr}}
3623 * PopSection:: @code{.popsection}
3624 * Previous:: @code{.previous}
3627 * Print:: @code{.print @var{string}}
3629 * Protected:: @code{.protected @var{names}}
3632 * Psize:: @code{.psize @var{lines}, @var{columns}}
3633 * Purgem:: @code{.purgem @var{name}}
3635 * PushSection:: @code{.pushsection @var{name}}
3638 * Quad:: @code{.quad @var{bignums}}
3639 * Rept:: @code{.rept @var{count}}
3640 * Sbttl:: @code{.sbttl "@var{subheading}"}
3642 * Scl:: @code{.scl @var{class}}
3643 * Section:: @code{.section @var{name}, @var{subsection}}
3646 * Set:: @code{.set @var{symbol}, @var{expression}}
3647 * Short:: @code{.short @var{expressions}}
3648 * Single:: @code{.single @var{flonums}}
3649 * Size:: @code{.size [@var{name} , @var{expression}]}
3650 * Skip:: @code{.skip @var{size} , @var{fill}}
3651 * Sleb128:: @code{.sleb128 @var{expressions}}
3652 * Space:: @code{.space @var{size} , @var{fill}}
3654 * Stab:: @code{.stabd, .stabn, .stabs}
3657 * String:: @code{.string "@var{str}"}
3658 * Struct:: @code{.struct @var{expression}}
3660 * SubSection:: @code{.subsection}
3661 * Symver:: @code{.symver @var{name},@var{name2@@nodename}}
3665 * Tag:: @code{.tag @var{structname}}
3668 * Text:: @code{.text @var{subsection}}
3669 * Title:: @code{.title "@var{heading}"}
3670 * Type:: @code{.type <@var{int} | @var{name} , @var{type description}>}
3671 * Uleb128:: @code{.uleb128 @var{expressions}}
3673 * Val:: @code{.val @var{addr}}
3677 * Version:: @code{.version "@var{string}"}
3678 * VTableEntry:: @code{.vtable_entry @var{table}, @var{offset}}
3679 * VTableInherit:: @code{.vtable_inherit @var{child}, @var{parent}}
3680 * Weak:: @code{.weak @var{names}}
3683 * Word:: @code{.word @var{expressions}}
3684 * Deprecated:: Deprecated Directives
3688 @section @code{.abort}
3690 @cindex @code{abort} directive
3691 @cindex stopping the assembly
3692 This directive stops the assembly immediately. It is for
3693 compatibility with other assemblers. The original idea was that the
3694 assembly language source would be piped into the assembler. If the sender
3695 of the source quit, it could use this directive tells @command{@value{AS}} to
3696 quit also. One day @code{.abort} will not be supported.
3700 @section @code{.ABORT}
3702 @cindex @code{ABORT} directive
3703 When producing COFF output, @command{@value{AS}} accepts this directive as a
3704 synonym for @samp{.abort}.
3707 When producing @code{b.out} output, @command{@value{AS}} accepts this directive,
3713 @section @code{.align @var{abs-expr}, @var{abs-expr}, @var{abs-expr}}
3715 @cindex padding the location counter
3716 @cindex @code{align} directive
3717 Pad the location counter (in the current subsection) to a particular storage
3718 boundary. The first expression (which must be absolute) is the alignment
3719 required, as described below.
3721 The second expression (also absolute) gives the fill value to be stored in the
3722 padding bytes. It (and the comma) may be omitted. If it is omitted, the
3723 padding bytes are normally zero. However, on some systems, if the section is
3724 marked as containing code and the fill value is omitted, the space is filled
3725 with no-op instructions.
3727 The third expression is also absolute, and is also optional. If it is present,
3728 it is the maximum number of bytes that should be skipped by this alignment
3729 directive. If doing the alignment would require skipping more bytes than the
3730 specified maximum, then the alignment is not done at all. You can omit the
3731 fill value (the second argument) entirely by simply using two commas after the
3732 required alignment; this can be useful if you want the alignment to be filled
3733 with no-op instructions when appropriate.
3735 The way the required alignment is specified varies from system to system.
3736 For the a29k, hppa, m68k, m88k, w65, sparc, and Hitachi SH, and i386 using ELF
3738 the first expression is the
3739 alignment request in bytes. For example @samp{.align 8} advances
3740 the location counter until it is a multiple of 8. If the location counter
3741 is already a multiple of 8, no change is needed.
3743 For other systems, including the i386 using a.out format, and the arm and
3744 strongarm, it is the
3745 number of low-order zero bits the location counter must have after
3746 advancement. For example @samp{.align 3} advances the location
3747 counter until it a multiple of 8. If the location counter is already a
3748 multiple of 8, no change is needed.
3750 This inconsistency is due to the different behaviors of the various
3751 native assemblers for these systems which GAS must emulate.
3752 GAS also provides @code{.balign} and @code{.p2align} directives,
3753 described later, which have a consistent behavior across all
3754 architectures (but are specific to GAS).
3757 @section @code{.ascii "@var{string}"}@dots{}
3759 @cindex @code{ascii} directive
3760 @cindex string literals
3761 @code{.ascii} expects zero or more string literals (@pxref{Strings})
3762 separated by commas. It assembles each string (with no automatic
3763 trailing zero byte) into consecutive addresses.
3766 @section @code{.asciz "@var{string}"}@dots{}
3768 @cindex @code{asciz} directive
3769 @cindex zero-terminated strings
3770 @cindex null-terminated strings
3771 @code{.asciz} is just like @code{.ascii}, but each string is followed by
3772 a zero byte. The ``z'' in @samp{.asciz} stands for ``zero''.
3775 @section @code{.balign[wl] @var{abs-expr}, @var{abs-expr}, @var{abs-expr}}
3777 @cindex padding the location counter given number of bytes
3778 @cindex @code{balign} directive
3779 Pad the location counter (in the current subsection) to a particular
3780 storage boundary. The first expression (which must be absolute) is the
3781 alignment request in bytes. For example @samp{.balign 8} advances
3782 the location counter until it is a multiple of 8. If the location counter
3783 is already a multiple of 8, no change is needed.
3785 The second expression (also absolute) gives the fill value to be stored in the
3786 padding bytes. It (and the comma) may be omitted. If it is omitted, the
3787 padding bytes are normally zero. However, on some systems, if the section is
3788 marked as containing code and the fill value is omitted, the space is filled
3789 with no-op instructions.
3791 The third expression is also absolute, and is also optional. If it is present,
3792 it is the maximum number of bytes that should be skipped by this alignment
3793 directive. If doing the alignment would require skipping more bytes than the
3794 specified maximum, then the alignment is not done at all. You can omit the
3795 fill value (the second argument) entirely by simply using two commas after the
3796 required alignment; this can be useful if you want the alignment to be filled
3797 with no-op instructions when appropriate.
3799 @cindex @code{balignw} directive
3800 @cindex @code{balignl} directive
3801 The @code{.balignw} and @code{.balignl} directives are variants of the
3802 @code{.balign} directive. The @code{.balignw} directive treats the fill
3803 pattern as a two byte word value. The @code{.balignl} directives treats the
3804 fill pattern as a four byte longword value. For example, @code{.balignw
3805 4,0x368d} will align to a multiple of 4. If it skips two bytes, they will be
3806 filled in with the value 0x368d (the exact placement of the bytes depends upon
3807 the endianness of the processor). If it skips 1 or 3 bytes, the fill value is
3811 @section @code{.byte @var{expressions}}
3813 @cindex @code{byte} directive
3814 @cindex integers, one byte
3815 @code{.byte} expects zero or more expressions, separated by commas.
3816 Each expression is assembled into the next byte.
3819 @section @code{.comm @var{symbol} , @var{length} }
3821 @cindex @code{comm} directive
3822 @cindex symbol, common
3823 @code{.comm} declares a common symbol named @var{symbol}. When linking, a
3824 common symbol in one object file may be merged with a defined or common symbol
3825 of the same name in another object file. If @code{@value{LD}} does not see a
3826 definition for the symbol--just one or more common symbols--then it will
3827 allocate @var{length} bytes of uninitialized memory. @var{length} must be an
3828 absolute expression. If @code{@value{LD}} sees multiple common symbols with
3829 the same name, and they do not all have the same size, it will allocate space
3830 using the largest size.
3833 When using ELF, the @code{.comm} directive takes an optional third argument.
3834 This is the desired alignment of the symbol, specified as a byte boundary (for
3835 example, an alignment of 16 means that the least significant 4 bits of the
3836 address should be zero). The alignment must be an absolute expression, and it
3837 must be a power of two. If @code{@value{LD}} allocates uninitialized memory
3838 for the common symbol, it will use the alignment when placing the symbol. If
3839 no alignment is specified, @command{@value{AS}} will set the alignment to the
3840 largest power of two less than or equal to the size of the symbol, up to a
3845 The syntax for @code{.comm} differs slightly on the HPPA. The syntax is
3846 @samp{@var{symbol} .comm, @var{length}}; @var{symbol} is optional.
3850 @section @code{.data @var{subsection}}
3852 @cindex @code{data} directive
3853 @code{.data} tells @command{@value{AS}} to assemble the following statements onto the
3854 end of the data subsection numbered @var{subsection} (which is an
3855 absolute expression). If @var{subsection} is omitted, it defaults
3860 @section @code{.def @var{name}}
3862 @cindex @code{def} directive
3863 @cindex COFF symbols, debugging
3864 @cindex debugging COFF symbols
3865 Begin defining debugging information for a symbol @var{name}; the
3866 definition extends until the @code{.endef} directive is encountered.
3869 This directive is only observed when @command{@value{AS}} is configured for COFF
3870 format output; when producing @code{b.out}, @samp{.def} is recognized,
3877 @section @code{.desc @var{symbol}, @var{abs-expression}}
3879 @cindex @code{desc} directive
3880 @cindex COFF symbol descriptor
3881 @cindex symbol descriptor, COFF
3882 This directive sets the descriptor of the symbol (@pxref{Symbol Attributes})
3883 to the low 16 bits of an absolute expression.
3886 The @samp{.desc} directive is not available when @command{@value{AS}} is
3887 configured for COFF output; it is only for @code{a.out} or @code{b.out}
3888 object format. For the sake of compatibility, @command{@value{AS}} accepts
3889 it, but produces no output, when configured for COFF.
3895 @section @code{.dim}
3897 @cindex @code{dim} directive
3898 @cindex COFF auxiliary symbol information
3899 @cindex auxiliary symbol information, COFF
3900 This directive is generated by compilers to include auxiliary debugging
3901 information in the symbol table. It is only permitted inside
3902 @code{.def}/@code{.endef} pairs.
3905 @samp{.dim} is only meaningful when generating COFF format output; when
3906 @command{@value{AS}} is generating @code{b.out}, it accepts this directive but
3912 @section @code{.double @var{flonums}}
3914 @cindex @code{double} directive
3915 @cindex floating point numbers (double)
3916 @code{.double} expects zero or more flonums, separated by commas. It
3917 assembles floating point numbers.
3919 The exact kind of floating point numbers emitted depends on how
3920 @command{@value{AS}} is configured. @xref{Machine Dependencies}.
3924 On the @value{TARGET} family @samp{.double} emits 64-bit floating-point numbers
3925 in @sc{ieee} format.
3930 @section @code{.eject}
3932 @cindex @code{eject} directive
3933 @cindex new page, in listings
3934 @cindex page, in listings
3935 @cindex listing control: new page
3936 Force a page break at this point, when generating assembly listings.
3939 @section @code{.else}
3941 @cindex @code{else} directive
3942 @code{.else} is part of the @command{@value{AS}} support for conditional
3943 assembly; @pxref{If,,@code{.if}}. It marks the beginning of a section
3944 of code to be assembled if the condition for the preceding @code{.if}
3948 @section @code{.elseif}
3950 @cindex @code{elseif} directive
3951 @code{.elseif} is part of the @command{@value{AS}} support for conditional
3952 assembly; @pxref{If,,@code{.if}}. It is shorthand for beginning a new
3953 @code{.if} block that would otherwise fill the entire @code{.else} section.
3956 @section @code{.end}
3958 @cindex @code{end} directive
3959 @code{.end} marks the end of the assembly file. @command{@value{AS}} does not
3960 process anything in the file past the @code{.end} directive.
3964 @section @code{.endef}
3966 @cindex @code{endef} directive
3967 This directive flags the end of a symbol definition begun with
3971 @samp{.endef} is only meaningful when generating COFF format output; if
3972 @command{@value{AS}} is configured to generate @code{b.out}, it accepts this
3973 directive but ignores it.
3978 @section @code{.endfunc}
3979 @cindex @code{endfunc} directive
3980 @code{.endfunc} marks the end of a function specified with @code{.func}.
3983 @section @code{.endif}
3985 @cindex @code{endif} directive
3986 @code{.endif} is part of the @command{@value{AS}} support for conditional assembly;
3987 it marks the end of a block of code that is only assembled
3988 conditionally. @xref{If,,@code{.if}}.
3991 @section @code{.equ @var{symbol}, @var{expression}}
3993 @cindex @code{equ} directive
3994 @cindex assigning values to symbols
3995 @cindex symbols, assigning values to
3996 This directive sets the value of @var{symbol} to @var{expression}.
3997 It is synonymous with @samp{.set}; @pxref{Set,,@code{.set}}.
4000 The syntax for @code{equ} on the HPPA is
4001 @samp{@var{symbol} .equ @var{expression}}.
4005 @section @code{.equiv @var{symbol}, @var{expression}}
4006 @cindex @code{equiv} directive
4007 The @code{.equiv} directive is like @code{.equ} and @code{.set}, except that
4008 the assembler will signal an error if @var{symbol} is already defined.
4010 Except for the contents of the error message, this is roughly equivalent to
4019 @section @code{.err}
4020 @cindex @code{err} directive
4021 If @command{@value{AS}} assembles a @code{.err} directive, it will print an error
4022 message and, unless the @option{-Z} option was used, it will not generate an
4023 object file. This can be used to signal error an conditionally compiled code.
4026 @section @code{.exitm}
4027 Exit early from the current macro definition. @xref{Macro}.
4030 @section @code{.extern}
4032 @cindex @code{extern} directive
4033 @code{.extern} is accepted in the source program---for compatibility
4034 with other assemblers---but it is ignored. @command{@value{AS}} treats
4035 all undefined symbols as external.
4038 @section @code{.fail @var{expression}}
4040 @cindex @code{fail} directive
4041 Generates an error or a warning. If the value of the @var{expression} is 500
4042 or more, @command{@value{AS}} will print a warning message. If the value is less
4043 than 500, @command{@value{AS}} will print an error message. The message will
4044 include the value of @var{expression}. This can occasionally be useful inside
4045 complex nested macros or conditional assembly.
4047 @ifclear no-file-dir
4049 @section @code{.file @var{string}}
4051 @cindex @code{file} directive
4052 @cindex logical file name
4053 @cindex file name, logical
4054 @code{.file} tells @command{@value{AS}} that we are about to start a new logical
4055 file. @var{string} is the new file name. In general, the filename is
4056 recognized whether or not it is surrounded by quotes @samp{"}; but if you wish
4057 to specify an empty file name, you must give the quotes--@code{""}. This
4058 statement may go away in future: it is only recognized to be compatible with
4059 old @command{@value{AS}} programs.
4061 In some configurations of @command{@value{AS}}, @code{.file} has already been
4062 removed to avoid conflicts with other assemblers. @xref{Machine Dependencies}.
4067 @section @code{.fill @var{repeat} , @var{size} , @var{value}}
4069 @cindex @code{fill} directive
4070 @cindex writing patterns in memory
4071 @cindex patterns, writing in memory
4072 @var{repeat}, @var{size} and @var{value} are absolute expressions.
4073 This emits @var{repeat} copies of @var{size} bytes. @var{Repeat}
4074 may be zero or more. @var{Size} may be zero or more, but if it is
4075 more than 8, then it is deemed to have the value 8, compatible with
4076 other people's assemblers. The contents of each @var{repeat} bytes
4077 is taken from an 8-byte number. The highest order 4 bytes are
4078 zero. The lowest order 4 bytes are @var{value} rendered in the
4079 byte-order of an integer on the computer @command{@value{AS}} is assembling for.
4080 Each @var{size} bytes in a repetition is taken from the lowest order
4081 @var{size} bytes of this number. Again, this bizarre behavior is
4082 compatible with other people's assemblers.
4084 @var{size} and @var{value} are optional.
4085 If the second comma and @var{value} are absent, @var{value} is
4086 assumed zero. If the first comma and following tokens are absent,
4087 @var{size} is assumed to be 1.
4090 @section @code{.float @var{flonums}}
4092 @cindex floating point numbers (single)
4093 @cindex @code{float} directive
4094 This directive assembles zero or more flonums, separated by commas. It
4095 has the same effect as @code{.single}.
4097 The exact kind of floating point numbers emitted depends on how
4098 @command{@value{AS}} is configured.
4099 @xref{Machine Dependencies}.
4103 On the @value{TARGET} family, @code{.float} emits 32-bit floating point numbers
4104 in @sc{ieee} format.
4109 @section @code{.func @var{name}[,@var{label}]}
4110 @cindex @code{func} directive
4111 @code{.func} emits debugging information to denote function @var{name}, and
4112 is ignored unless the file is assembled with debugging enabled.
4113 Only @samp{--gstabs} is currently supported.
4114 @var{label} is the entry point of the function and if omitted @var{name}
4115 prepended with the @samp{leading char} is used.
4116 @samp{leading char} is usually @code{_} or nothing, depending on the target.
4117 All functions are currently defined to have @code{void} return type.
4118 The function must be terminated with @code{.endfunc}.
4121 @section @code{.global @var{symbol}}, @code{.globl @var{symbol}}
4123 @cindex @code{global} directive
4124 @cindex symbol, making visible to linker
4125 @code{.global} makes the symbol visible to @code{@value{LD}}. If you define
4126 @var{symbol} in your partial program, its value is made available to
4127 other partial programs that are linked with it. Otherwise,
4128 @var{symbol} takes its attributes from a symbol of the same name
4129 from another file linked into the same program.
4131 Both spellings (@samp{.globl} and @samp{.global}) are accepted, for
4132 compatibility with other assemblers.
4135 On the HPPA, @code{.global} is not always enough to make it accessible to other
4136 partial programs. You may need the HPPA-only @code{.EXPORT} directive as well.
4137 @xref{HPPA Directives,, HPPA Assembler Directives}.
4142 @section @code{.hidden @var{names}}
4144 @cindex @code{.hidden} directive
4146 This one of the ELF visibility directives. The other two are
4147 @code{.internal} (@pxref{Internal,,@code{.internal}}) and
4148 @code{.protected} (@pxref{Protected,,@code{.protected}}).
4150 This directive overrides the named symbols default visibility (which is set by
4151 their binding: local, global or weak). The directive sets the visibility to
4152 @code{hidden} which means that the symbols are not visible to other components.
4153 Such symbols are always considered to be @code{protected} as well.
4157 @section @code{.hword @var{expressions}}
4159 @cindex @code{hword} directive
4160 @cindex integers, 16-bit
4161 @cindex numbers, 16-bit
4162 @cindex sixteen bit integers
4163 This expects zero or more @var{expressions}, and emits
4164 a 16 bit number for each.
4167 This directive is a synonym for @samp{.short}; depending on the target
4168 architecture, it may also be a synonym for @samp{.word}.
4172 This directive is a synonym for @samp{.short}.
4175 This directive is a synonym for both @samp{.short} and @samp{.word}.
4180 @section @code{.ident}
4182 @cindex @code{ident} directive
4183 This directive is used by some assemblers to place tags in object files.
4184 @command{@value{AS}} simply accepts the directive for source-file
4185 compatibility with such assemblers, but does not actually emit anything
4189 @section @code{.if @var{absolute expression}}
4191 @cindex conditional assembly
4192 @cindex @code{if} directive
4193 @code{.if} marks the beginning of a section of code which is only
4194 considered part of the source program being assembled if the argument
4195 (which must be an @var{absolute expression}) is non-zero. The end of
4196 the conditional section of code must be marked by @code{.endif}
4197 (@pxref{Endif,,@code{.endif}}); optionally, you may include code for the
4198 alternative condition, flagged by @code{.else} (@pxref{Else,,@code{.else}}).
4199 If you have several conditions to check, @code{.elseif} may be used to avoid
4200 nesting blocks if/else within each subsequent @code{.else} block.
4202 The following variants of @code{.if} are also supported:
4204 @cindex @code{ifdef} directive
4205 @item .ifdef @var{symbol}
4206 Assembles the following section of code if the specified @var{symbol}
4209 @cindex @code{ifc} directive
4210 @item .ifc @var{string1},@var{string2}
4211 Assembles the following section of code if the two strings are the same. The
4212 strings may be optionally quoted with single quotes. If they are not quoted,
4213 the first string stops at the first comma, and the second string stops at the
4214 end of the line. Strings which contain whitespace should be quoted. The
4215 string comparison is case sensitive.
4217 @cindex @code{ifeq} directive
4218 @item .ifeq @var{absolute expression}
4219 Assembles the following section of code if the argument is zero.
4221 @cindex @code{ifeqs} directive
4222 @item .ifeqs @var{string1},@var{string2}
4223 Another form of @code{.ifc}. The strings must be quoted using double quotes.
4225 @cindex @code{ifge} directive
4226 @item .ifge @var{absolute expression}
4227 Assembles the following section of code if the argument is greater than or
4230 @cindex @code{ifgt} directive
4231 @item .ifgt @var{absolute expression}
4232 Assembles the following section of code if the argument is greater than zero.
4234 @cindex @code{ifle} directive
4235 @item .ifle @var{absolute expression}
4236 Assembles the following section of code if the argument is less than or equal
4239 @cindex @code{iflt} directive
4240 @item .iflt @var{absolute expression}
4241 Assembles the following section of code if the argument is less than zero.
4243 @cindex @code{ifnc} directive
4244 @item .ifnc @var{string1},@var{string2}.
4245 Like @code{.ifc}, but the sense of the test is reversed: this assembles the
4246 following section of code if the two strings are not the same.
4248 @cindex @code{ifndef} directive
4249 @cindex @code{ifnotdef} directive
4250 @item .ifndef @var{symbol}
4251 @itemx .ifnotdef @var{symbol}
4252 Assembles the following section of code if the specified @var{symbol}
4253 has not been defined. Both spelling variants are equivalent.
4255 @cindex @code{ifne} directive
4256 @item .ifne @var{absolute expression}
4257 Assembles the following section of code if the argument is not equal to zero
4258 (in other words, this is equivalent to @code{.if}).
4260 @cindex @code{ifnes} directive
4261 @item .ifnes @var{string1},@var{string2}
4262 Like @code{.ifeqs}, but the sense of the test is reversed: this assembles the
4263 following section of code if the two strings are not the same.
4267 @section @code{.incbin "@var{file}"[,@var{skip}[,@var{count}]]}
4269 @cindex @code{incbin} directive
4270 @cindex binary files, including
4271 The @code{incbin} directive includes @var{file} verbatim at the current
4272 location. You can control the search paths used with the @samp{-I} command-line
4273 option (@pxref{Invoking,,Command-Line Options}). Quotation marks are required
4276 The @var{skip} argument skips a number of bytes from the start of the
4277 @var{file}. The @var{count} argument indicates the maximum number of bytes to
4278 read. Note that the data is not aligned in any way, so it is the user's
4279 responsibility to make sure that proper alignment is provided both before and
4280 after the @code{incbin} directive.
4283 @section @code{.include "@var{file}"}
4285 @cindex @code{include} directive
4286 @cindex supporting files, including
4287 @cindex files, including
4288 This directive provides a way to include supporting files at specified
4289 points in your source program. The code from @var{file} is assembled as
4290 if it followed the point of the @code{.include}; when the end of the
4291 included file is reached, assembly of the original file continues. You
4292 can control the search paths used with the @samp{-I} command-line option
4293 (@pxref{Invoking,,Command-Line Options}). Quotation marks are required
4297 @section @code{.int @var{expressions}}
4299 @cindex @code{int} directive
4300 @cindex integers, 32-bit
4301 Expect zero or more @var{expressions}, of any section, separated by commas.
4302 For each expression, emit a number that, at run time, is the value of that
4303 expression. The byte order and bit size of the number depends on what kind
4304 of target the assembly is for.
4308 On the H8/500 and most forms of the H8/300, @code{.int} emits 16-bit
4309 integers. On the H8/300H and the Hitachi SH, however, @code{.int} emits
4316 @section @code{.internal @var{names}}
4318 @cindex @code{.internal} directive
4320 This one of the ELF visibility directives. The other two are
4321 @code{.hidden} (@pxref{Hidden,,@code{.hidden}}) and
4322 @code{.protected} (@pxref{Protected,,@code{.protected}}).
4324 This directive overrides the named symbols default visibility (which is set by
4325 their binding: local, global or weak). The directive sets the visibility to
4326 @code{internal} which means that the symbols are considered to be @code{hidden}
4327 (ie not visible to other components), and that some extra, processor specific
4328 processing must also be performed upon the symbols as well.
4332 @section @code{.irp @var{symbol},@var{values}}@dots{}
4334 @cindex @code{irp} directive
4335 Evaluate a sequence of statements assigning different values to @var{symbol}.
4336 The sequence of statements starts at the @code{.irp} directive, and is
4337 terminated by an @code{.endr} directive. For each @var{value}, @var{symbol} is
4338 set to @var{value}, and the sequence of statements is assembled. If no
4339 @var{value} is listed, the sequence of statements is assembled once, with
4340 @var{symbol} set to the null string. To refer to @var{symbol} within the
4341 sequence of statements, use @var{\symbol}.
4343 For example, assembling
4351 is equivalent to assembling
4360 @section @code{.irpc @var{symbol},@var{values}}@dots{}
4362 @cindex @code{irpc} directive
4363 Evaluate a sequence of statements assigning different values to @var{symbol}.
4364 The sequence of statements starts at the @code{.irpc} directive, and is
4365 terminated by an @code{.endr} directive. For each character in @var{value},
4366 @var{symbol} is set to the character, and the sequence of statements is
4367 assembled. If no @var{value} is listed, the sequence of statements is
4368 assembled once, with @var{symbol} set to the null string. To refer to
4369 @var{symbol} within the sequence of statements, use @var{\symbol}.
4371 For example, assembling
4379 is equivalent to assembling
4388 @section @code{.lcomm @var{symbol} , @var{length}}
4390 @cindex @code{lcomm} directive
4391 @cindex local common symbols
4392 @cindex symbols, local common
4393 Reserve @var{length} (an absolute expression) bytes for a local common
4394 denoted by @var{symbol}. The section and value of @var{symbol} are
4395 those of the new local common. The addresses are allocated in the bss
4396 section, so that at run-time the bytes start off zeroed. @var{Symbol}
4397 is not declared global (@pxref{Global,,@code{.global}}), so is normally
4398 not visible to @code{@value{LD}}.
4401 Some targets permit a third argument to be used with @code{.lcomm}. This
4402 argument specifies the desired alignment of the symbol in the bss section.
4406 The syntax for @code{.lcomm} differs slightly on the HPPA. The syntax is
4407 @samp{@var{symbol} .lcomm, @var{length}}; @var{symbol} is optional.
4411 @section @code{.lflags}
4413 @cindex @code{lflags} directive (ignored)
4414 @command{@value{AS}} accepts this directive, for compatibility with other
4415 assemblers, but ignores it.
4417 @ifclear no-line-dir
4419 @section @code{.line @var{line-number}}
4421 @cindex @code{line} directive
4425 @section @code{.ln @var{line-number}}
4427 @cindex @code{ln} directive
4429 @cindex logical line number
4431 Change the logical line number. @var{line-number} must be an absolute
4432 expression. The next line has that logical line number. Therefore any other
4433 statements on the current line (after a statement separator character) are
4434 reported as on logical line number @var{line-number} @minus{} 1. One day
4435 @command{@value{AS}} will no longer support this directive: it is recognized only
4436 for compatibility with existing assembler programs.
4440 @emph{Warning:} In the AMD29K configuration of @value{AS}, this command is
4441 not available; use the synonym @code{.ln} in that context.
4446 @ifclear no-line-dir
4447 Even though this is a directive associated with the @code{a.out} or
4448 @code{b.out} object-code formats, @command{@value{AS}} still recognizes it
4449 when producing COFF output, and treats @samp{.line} as though it
4450 were the COFF @samp{.ln} @emph{if} it is found outside a
4451 @code{.def}/@code{.endef} pair.
4453 Inside a @code{.def}, @samp{.line} is, instead, one of the directives
4454 used by compilers to generate auxiliary symbol information for
4459 @section @code{.linkonce [@var{type}]}
4461 @cindex @code{linkonce} directive
4462 @cindex common sections
4463 Mark the current section so that the linker only includes a single copy of it.
4464 This may be used to include the same section in several different object files,
4465 but ensure that the linker will only include it once in the final output file.
4466 The @code{.linkonce} pseudo-op must be used for each instance of the section.
4467 Duplicate sections are detected based on the section name, so it should be
4470 This directive is only supported by a few object file formats; as of this
4471 writing, the only object file format which supports it is the Portable
4472 Executable format used on Windows NT.
4474 The @var{type} argument is optional. If specified, it must be one of the
4475 following strings. For example:
4479 Not all types may be supported on all object file formats.
4483 Silently discard duplicate sections. This is the default.
4486 Warn if there are duplicate sections, but still keep only one copy.
4489 Warn if any of the duplicates have different sizes.
4492 Warn if any of the duplicates do not have exactly the same contents.
4496 @section @code{.ln @var{line-number}}
4498 @cindex @code{ln} directive
4499 @ifclear no-line-dir
4500 @samp{.ln} is a synonym for @samp{.line}.
4503 Tell @command{@value{AS}} to change the logical line number. @var{line-number}
4504 must be an absolute expression. The next line has that logical
4505 line number, so any other statements on the current line (after a
4506 statement separator character @code{;}) are reported as on logical
4507 line number @var{line-number} @minus{} 1.
4510 This directive is accepted, but ignored, when @command{@value{AS}} is
4511 configured for @code{b.out}; its effect is only associated with COFF
4517 @section @code{.mri @var{val}}
4519 @cindex @code{mri} directive
4520 @cindex MRI mode, temporarily
4521 If @var{val} is non-zero, this tells @command{@value{AS}} to enter MRI mode. If
4522 @var{val} is zero, this tells @command{@value{AS}} to exit MRI mode. This change
4523 affects code assembled until the next @code{.mri} directive, or until the end
4524 of the file. @xref{M, MRI mode, MRI mode}.
4527 @section @code{.list}
4529 @cindex @code{list} directive
4530 @cindex listing control, turning on
4531 Control (in conjunction with the @code{.nolist} directive) whether or
4532 not assembly listings are generated. These two directives maintain an
4533 internal counter (which is zero initially). @code{.list} increments the
4534 counter, and @code{.nolist} decrements it. Assembly listings are
4535 generated whenever the counter is greater than zero.
4537 By default, listings are disabled. When you enable them (with the
4538 @samp{-a} command line option; @pxref{Invoking,,Command-Line Options}),
4539 the initial value of the listing counter is one.
4542 @section @code{.long @var{expressions}}
4544 @cindex @code{long} directive
4545 @code{.long} is the same as @samp{.int}, @pxref{Int,,@code{.int}}.
4548 @c no one seems to know what this is for or whether this description is
4549 @c what it really ought to do
4551 @section @code{.lsym @var{symbol}, @var{expression}}
4553 @cindex @code{lsym} directive
4554 @cindex symbol, not referenced in assembly
4555 @code{.lsym} creates a new symbol named @var{symbol}, but does not put it in
4556 the hash table, ensuring it cannot be referenced by name during the
4557 rest of the assembly. This sets the attributes of the symbol to be
4558 the same as the expression value:
4560 @var{other} = @var{descriptor} = 0
4561 @var{type} = @r{(section of @var{expression})}
4562 @var{value} = @var{expression}
4565 The new symbol is not flagged as external.
4569 @section @code{.macro}
4572 The commands @code{.macro} and @code{.endm} allow you to define macros that
4573 generate assembly output. For example, this definition specifies a macro
4574 @code{sum} that puts a sequence of numbers into memory:
4577 .macro sum from=0, to=5
4586 With that definition, @samp{SUM 0,5} is equivalent to this assembly input:
4598 @item .macro @var{macname}
4599 @itemx .macro @var{macname} @var{macargs} @dots{}
4600 @cindex @code{macro} directive
4601 Begin the definition of a macro called @var{macname}. If your macro
4602 definition requires arguments, specify their names after the macro name,
4603 separated by commas or spaces. You can supply a default value for any
4604 macro argument by following the name with @samp{=@var{deflt}}. For
4605 example, these are all valid @code{.macro} statements:
4609 Begin the definition of a macro called @code{comm}, which takes no
4612 @item .macro plus1 p, p1
4613 @itemx .macro plus1 p p1
4614 Either statement begins the definition of a macro called @code{plus1},
4615 which takes two arguments; within the macro definition, write
4616 @samp{\p} or @samp{\p1} to evaluate the arguments.
4618 @item .macro reserve_str p1=0 p2
4619 Begin the definition of a macro called @code{reserve_str}, with two
4620 arguments. The first argument has a default value, but not the second.
4621 After the definition is complete, you can call the macro either as
4622 @samp{reserve_str @var{a},@var{b}} (with @samp{\p1} evaluating to
4623 @var{a} and @samp{\p2} evaluating to @var{b}), or as @samp{reserve_str
4624 ,@var{b}} (with @samp{\p1} evaluating as the default, in this case
4625 @samp{0}, and @samp{\p2} evaluating to @var{b}).
4628 When you call a macro, you can specify the argument values either by
4629 position, or by keyword. For example, @samp{sum 9,17} is equivalent to
4630 @samp{sum to=17, from=9}.
4633 @cindex @code{endm} directive
4634 Mark the end of a macro definition.
4637 @cindex @code{exitm} directive
4638 Exit early from the current macro definition.
4640 @cindex number of macros executed
4641 @cindex macros, count executed
4643 @command{@value{AS}} maintains a counter of how many macros it has
4644 executed in this pseudo-variable; you can copy that number to your
4645 output with @samp{\@@}, but @emph{only within a macro definition}.
4648 @item LOCAL @var{name} [ , @dots{} ]
4649 @emph{Warning: @code{LOCAL} is only available if you select ``alternate
4650 macro syntax'' with @samp{-a} or @samp{--alternate}.} @xref{Alternate,,
4651 Alternate macro syntax}.
4653 Generate a string replacement for each of the @var{name} arguments, and
4654 replace any instances of @var{name} in each macro expansion. The
4655 replacement string is unique in the assembly, and different for each
4656 separate macro expansion. @code{LOCAL} allows you to write macros that
4657 define symbols, without fear of conflict between separate macro expansions.
4662 @section @code{.nolist}
4664 @cindex @code{nolist} directive
4665 @cindex listing control, turning off
4666 Control (in conjunction with the @code{.list} directive) whether or
4667 not assembly listings are generated. These two directives maintain an
4668 internal counter (which is zero initially). @code{.list} increments the
4669 counter, and @code{.nolist} decrements it. Assembly listings are
4670 generated whenever the counter is greater than zero.
4673 @section @code{.octa @var{bignums}}
4675 @c FIXME: double size emitted for "octa" on i960, others? Or warn?
4676 @cindex @code{octa} directive
4677 @cindex integer, 16-byte
4678 @cindex sixteen byte integer
4679 This directive expects zero or more bignums, separated by commas. For each
4680 bignum, it emits a 16-byte integer.
4682 The term ``octa'' comes from contexts in which a ``word'' is two bytes;
4683 hence @emph{octa}-word for 16 bytes.
4686 @section @code{.org @var{new-lc} , @var{fill}}
4688 @cindex @code{org} directive
4689 @cindex location counter, advancing
4690 @cindex advancing location counter
4691 @cindex current address, advancing
4692 Advance the location counter of the current section to
4693 @var{new-lc}. @var{new-lc} is either an absolute expression or an
4694 expression with the same section as the current subsection. That is,
4695 you can't use @code{.org} to cross sections: if @var{new-lc} has the
4696 wrong section, the @code{.org} directive is ignored. To be compatible
4697 with former assemblers, if the section of @var{new-lc} is absolute,
4698 @command{@value{AS}} issues a warning, then pretends the section of @var{new-lc}
4699 is the same as the current subsection.
4701 @code{.org} may only increase the location counter, or leave it
4702 unchanged; you cannot use @code{.org} to move the location counter
4705 @c double negative used below "not undefined" because this is a specific
4706 @c reference to "undefined" (as SEG_UNKNOWN is called in this manual)
4707 @c section. doc@cygnus.com 18feb91
4708 Because @command{@value{AS}} tries to assemble programs in one pass, @var{new-lc}
4709 may not be undefined. If you really detest this restriction we eagerly await
4710 a chance to share your improved assembler.
4712 Beware that the origin is relative to the start of the section, not
4713 to the start of the subsection. This is compatible with other
4714 people's assemblers.
4716 When the location counter (of the current subsection) is advanced, the
4717 intervening bytes are filled with @var{fill} which should be an
4718 absolute expression. If the comma and @var{fill} are omitted,
4719 @var{fill} defaults to zero.
4722 @section @code{.p2align[wl] @var{abs-expr}, @var{abs-expr}, @var{abs-expr}}
4724 @cindex padding the location counter given a power of two
4725 @cindex @code{p2align} directive
4726 Pad the location counter (in the current subsection) to a particular
4727 storage boundary. The first expression (which must be absolute) is the
4728 number of low-order zero bits the location counter must have after
4729 advancement. For example @samp{.p2align 3} advances the location
4730 counter until it a multiple of 8. If the location counter is already a
4731 multiple of 8, no change is needed.
4733 The second expression (also absolute) gives the fill value to be stored in the
4734 padding bytes. It (and the comma) may be omitted. If it is omitted, the
4735 padding bytes are normally zero. However, on some systems, if the section is
4736 marked as containing code and the fill value is omitted, the space is filled
4737 with no-op instructions.
4739 The third expression is also absolute, and is also optional. If it is present,
4740 it is the maximum number of bytes that should be skipped by this alignment
4741 directive. If doing the alignment would require skipping more bytes than the
4742 specified maximum, then the alignment is not done at all. You can omit the
4743 fill value (the second argument) entirely by simply using two commas after the
4744 required alignment; this can be useful if you want the alignment to be filled
4745 with no-op instructions when appropriate.
4747 @cindex @code{p2alignw} directive
4748 @cindex @code{p2alignl} directive
4749 The @code{.p2alignw} and @code{.p2alignl} directives are variants of the
4750 @code{.p2align} directive. The @code{.p2alignw} directive treats the fill
4751 pattern as a two byte word value. The @code{.p2alignl} directives treats the
4752 fill pattern as a four byte longword value. For example, @code{.p2alignw
4753 2,0x368d} will align to a multiple of 4. If it skips two bytes, they will be
4754 filled in with the value 0x368d (the exact placement of the bytes depends upon
4755 the endianness of the processor). If it skips 1 or 3 bytes, the fill value is
4760 @section @code{.previous}
4762 @cindex @code{.previous} directive
4763 @cindex Section Stack
4764 This is one of the ELF section stack manipulation directives. The others are
4765 @code{.section} (@pxref{Section}), @code{.subsection} (@pxref{SubSection}),
4766 @code{.pushsection} (@pxref{PushSection}), and @code{.popsection}
4767 (@pxref{PopSection}).
4769 This directive swaps the current section (and subsection) with most recently
4770 referenced section (and subsection) prior to this one. Multiple
4771 @code{.previous} directives in a row will flip between two sections (and their
4774 In terms of the section stack, this directive swaps the current section with
4775 the top section on the section stack.
4780 @section @code{.popsection}
4782 @cindex @code{.popsection} directive
4783 @cindex Section Stack
4784 This is one of the ELF section stack manipulation directives. The others are
4785 @code{.section} (@pxref{Section}), @code{.subsection} (@pxref{SubSection}),
4786 @code{.pushsection} (@pxref{PushSection}), and @code{.previous}
4789 This directive replaces the current section (and subsection) with the top
4790 section (and subsection) on the section stack. This section is popped off the
4795 @section @code{.print @var{string}}
4797 @cindex @code{print} directive
4798 @command{@value{AS}} will print @var{string} on the standard output during
4799 assembly. You must put @var{string} in double quotes.
4803 @section @code{.protected @var{names}}
4805 @cindex @code{.protected} directive
4807 This one of the ELF visibility directives. The other two are
4808 @code{.hidden} (@pxref{Hidden}) and @code{.internal} (@pxref{Internal}).
4810 This directive overrides the named symbols default visibility (which is set by
4811 their binding: local, global or weak). The directive sets the visibility to
4812 @code{protected} which means that any references to the symbols from within the
4813 components that defines them must be resolved to the definition in that
4814 component, even if a definition in another component would normally preempt
4819 @section @code{.psize @var{lines} , @var{columns}}
4821 @cindex @code{psize} directive
4822 @cindex listing control: paper size
4823 @cindex paper size, for listings
4824 Use this directive to declare the number of lines---and, optionally, the
4825 number of columns---to use for each page, when generating listings.
4827 If you do not use @code{.psize}, listings use a default line-count
4828 of 60. You may omit the comma and @var{columns} specification; the
4829 default width is 200 columns.
4831 @command{@value{AS}} generates formfeeds whenever the specified number of
4832 lines is exceeded (or whenever you explicitly request one, using
4835 If you specify @var{lines} as @code{0}, no formfeeds are generated save
4836 those explicitly specified with @code{.eject}.
4839 @section @code{.purgem @var{name}}
4841 @cindex @code{purgem} directive
4842 Undefine the macro @var{name}, so that later uses of the string will not be
4843 expanded. @xref{Macro}.
4847 @section @code{.pushsection @var{name} , @var{subsection}}
4849 @cindex @code{.pushsection} directive
4850 @cindex Section Stack
4851 This is one of the ELF section stack manipulation directives. The others are
4852 @code{.section} (@pxref{Section}), @code{.subsection} (@pxref{SubSection}),
4853 @code{.popsection} (@pxref{PopSection}), and @code{.previous}
4856 This directive is a synonym for @code{.section}. It pushes the current section
4857 (and subsection) onto the top of the section stack, and then replaces the
4858 current section and subsection with @code{name} and @code{subsection}.
4862 @section @code{.quad @var{bignums}}
4864 @cindex @code{quad} directive
4865 @code{.quad} expects zero or more bignums, separated by commas. For
4866 each bignum, it emits
4868 an 8-byte integer. If the bignum won't fit in 8 bytes, it prints a
4869 warning message; and just takes the lowest order 8 bytes of the bignum.
4870 @cindex eight-byte integer
4871 @cindex integer, 8-byte
4873 The term ``quad'' comes from contexts in which a ``word'' is two bytes;
4874 hence @emph{quad}-word for 8 bytes.
4877 a 16-byte integer. If the bignum won't fit in 16 bytes, it prints a
4878 warning message; and just takes the lowest order 16 bytes of the bignum.
4879 @cindex sixteen-byte integer
4880 @cindex integer, 16-byte
4884 @section @code{.rept @var{count}}
4886 @cindex @code{rept} directive
4887 Repeat the sequence of lines between the @code{.rept} directive and the next
4888 @code{.endr} directive @var{count} times.
4890 For example, assembling
4898 is equivalent to assembling
4907 @section @code{.sbttl "@var{subheading}"}
4909 @cindex @code{sbttl} directive
4910 @cindex subtitles for listings
4911 @cindex listing control: subtitle
4912 Use @var{subheading} as the title (third line, immediately after the
4913 title line) when generating assembly listings.
4915 This directive affects subsequent pages, as well as the current page if
4916 it appears within ten lines of the top of a page.
4920 @section @code{.scl @var{class}}
4922 @cindex @code{scl} directive
4923 @cindex symbol storage class (COFF)
4924 @cindex COFF symbol storage class
4925 Set the storage-class value for a symbol. This directive may only be
4926 used inside a @code{.def}/@code{.endef} pair. Storage class may flag
4927 whether a symbol is static or external, or it may record further
4928 symbolic debugging information.
4931 The @samp{.scl} directive is primarily associated with COFF output; when
4932 configured to generate @code{b.out} output format, @command{@value{AS}}
4933 accepts this directive but ignores it.
4938 @section @code{.section @var{name}} (COFF version)
4940 @cindex @code{section} directive
4941 @cindex named section
4942 Use the @code{.section} directive to assemble the following code into a section
4945 This directive is only supported for targets that actually support arbitrarily
4946 named sections; on @code{a.out} targets, for example, it is not accepted, even
4947 with a standard @code{a.out} section name.
4949 For COFF targets, the @code{.section} directive is used in one of the following
4953 .section @var{name}[, "@var{flags}"]
4954 .section @var{name}[, @var{subsegment}]
4957 If the optional argument is quoted, it is taken as flags to use for the
4958 section. Each flag is a single character. The following flags are recognized:
4961 bss section (uninitialized data)
4963 section is not loaded
4973 shared section (meaningful for PE targets)
4976 If no flags are specified, the default flags depend upon the section name. If
4977 the section name is not recognized, the default will be for the section to be
4978 loaded and writable. Note the @code{n} and @code{w} flags remove attributes
4979 from the section, rather than adding them, so if they are used on their own it
4980 will be as if no flags had been specified at all.
4982 If the optional argument to the @code{.section} directive is not quoted, it is
4983 taken as a subsegment number (@pxref{Sub-Sections}).
4986 @section @code{.section @var{name}} (ELF version)
4988 @cindex @code{section} directive
4989 @cindex named section
4991 @cindex Section Stack
4992 This is one of the ELF section stack manipulation directives. The others are
4993 @code{.subsection} (@pxref{SubSection}), @code{.pushsection}
4994 (@pxref{PushSection}), @code{.popsection} (@pxref{PopSection}), and
4995 @code{.previous} (@pxref{Previous}).
4998 For ELF targets, the @code{.section} directive is used like this:
5001 .section @var{name} [, "@var{flags}"[, @@@var{type}[, @@@var{entsize}]]]
5004 The optional @var{flags} argument is a quoted string which may contain any
5005 combination of the following characters:
5008 section is allocatable
5012 section is executable
5014 section is mergeable
5016 section contains zero terminated strings
5019 The optional @var{type} argument may contain one of the following constants:
5022 section contains data
5024 section does not contain data (i.e., section only occupies space)
5027 If @var{flags} contains @code{M} flag, @var{type} argument must be specified
5028 as well as @var{entsize} argument. Sections with @code{M} flag but not
5029 @code{S} flag must contain fixed size constants, each @var{entsize} octets
5030 long. Sections with both @code{M} and @code{S} must contain zero terminated
5031 strings where each character is @var{entsize} bytes long. The linker may remove
5032 duplicates within sections with the same name, same entity size and same flags.
5034 If no flags are specified, the default flags depend upon the section name. If
5035 the section name is not recognized, the default will be for the section to have
5036 none of the above flags: it will not be allocated in memory, nor writable, nor
5037 executable. The section will contain data.
5039 For ELF targets, the assembler supports another type of @code{.section}
5040 directive for compatibility with the Solaris assembler:
5043 .section "@var{name}"[, @var{flags}...]
5046 Note that the section name is quoted. There may be a sequence of comma
5050 section is allocatable
5054 section is executable
5057 This directive replaces the current section and subsection. The replaced
5058 section and subsection are pushed onto the section stack. See the contents of
5059 the gas testsuite directory @code{gas/testsuite/gas/elf} for some examples of
5060 how this directive and the other section stack directives work.
5063 @section @code{.set @var{symbol}, @var{expression}}
5065 @cindex @code{set} directive
5066 @cindex symbol value, setting
5067 Set the value of @var{symbol} to @var{expression}. This
5068 changes @var{symbol}'s value and type to conform to
5069 @var{expression}. If @var{symbol} was flagged as external, it remains
5070 flagged (@pxref{Symbol Attributes}).
5072 You may @code{.set} a symbol many times in the same assembly.
5074 If you @code{.set} a global symbol, the value stored in the object
5075 file is the last value stored into it.
5078 The syntax for @code{set} on the HPPA is
5079 @samp{@var{symbol} .set @var{expression}}.
5083 @section @code{.short @var{expressions}}
5085 @cindex @code{short} directive
5087 @code{.short} is normally the same as @samp{.word}.
5088 @xref{Word,,@code{.word}}.
5090 In some configurations, however, @code{.short} and @code{.word} generate
5091 numbers of different lengths; @pxref{Machine Dependencies}.
5095 @code{.short} is the same as @samp{.word}. @xref{Word,,@code{.word}}.
5098 This expects zero or more @var{expressions}, and emits
5099 a 16 bit number for each.
5104 @section @code{.single @var{flonums}}
5106 @cindex @code{single} directive
5107 @cindex floating point numbers (single)
5108 This directive assembles zero or more flonums, separated by commas. It
5109 has the same effect as @code{.float}.
5111 The exact kind of floating point numbers emitted depends on how
5112 @command{@value{AS}} is configured. @xref{Machine Dependencies}.
5116 On the @value{TARGET} family, @code{.single} emits 32-bit floating point
5117 numbers in @sc{ieee} format.
5122 @section @code{.size} (COFF version)
5124 @cindex @code{size} directive
5125 This directive is generated by compilers to include auxiliary debugging
5126 information in the symbol table. It is only permitted inside
5127 @code{.def}/@code{.endef} pairs.
5130 @samp{.size} is only meaningful when generating COFF format output; when
5131 @command{@value{AS}} is generating @code{b.out}, it accepts this directive but
5135 @section @code{.size @var{name} , @var{expression}} (ELF version)
5136 @cindex @code{size} directive
5138 This directive is used to set the size associated with a symbol @var{name}.
5139 The size in bytes is computed from @var{expression} which can make use of label
5140 arithmetic. This directive is typically used to set the size of function
5144 @section @code{.sleb128 @var{expressions}}
5146 @cindex @code{sleb128} directive
5147 @var{sleb128} stands for ``signed little endian base 128.'' This is a
5148 compact, variable length representation of numbers used by the DWARF
5149 symbolic debugging format. @xref{Uleb128,@code{.uleb128}}.
5151 @ifclear no-space-dir
5153 @section @code{.skip @var{size} , @var{fill}}
5155 @cindex @code{skip} directive
5156 @cindex filling memory
5157 This directive emits @var{size} bytes, each of value @var{fill}. Both
5158 @var{size} and @var{fill} are absolute expressions. If the comma and
5159 @var{fill} are omitted, @var{fill} is assumed to be zero. This is the same as
5163 @section @code{.space @var{size} , @var{fill}}
5165 @cindex @code{space} directive
5166 @cindex filling memory
5167 This directive emits @var{size} bytes, each of value @var{fill}. Both
5168 @var{size} and @var{fill} are absolute expressions. If the comma
5169 and @var{fill} are omitted, @var{fill} is assumed to be zero. This is the same
5174 @emph{Warning:} @code{.space} has a completely different meaning for HPPA
5175 targets; use @code{.block} as a substitute. See @cite{HP9000 Series 800
5176 Assembly Language Reference Manual} (HP 92432-90001) for the meaning of the
5177 @code{.space} directive. @xref{HPPA Directives,,HPPA Assembler Directives},
5186 @section @code{.space}
5187 @cindex @code{space} directive
5189 On the AMD 29K, this directive is ignored; it is accepted for
5190 compatibility with other AMD 29K assemblers.
5193 @emph{Warning:} In most versions of the @sc{gnu} assembler, the directive
5194 @code{.space} has the effect of @code{.block} @xref{Machine Dependencies}.
5200 @section @code{.stabd, .stabn, .stabs}
5202 @cindex symbolic debuggers, information for
5203 @cindex @code{stab@var{x}} directives
5204 There are three directives that begin @samp{.stab}.
5205 All emit symbols (@pxref{Symbols}), for use by symbolic debuggers.
5206 The symbols are not entered in the @command{@value{AS}} hash table: they
5207 cannot be referenced elsewhere in the source file.
5208 Up to five fields are required:
5212 This is the symbol's name. It may contain any character except
5213 @samp{\000}, so is more general than ordinary symbol names. Some
5214 debuggers used to code arbitrarily complex structures into symbol names
5218 An absolute expression. The symbol's type is set to the low 8 bits of
5219 this expression. Any bit pattern is permitted, but @code{@value{LD}}
5220 and debuggers choke on silly bit patterns.
5223 An absolute expression. The symbol's ``other'' attribute is set to the
5224 low 8 bits of this expression.
5227 An absolute expression. The symbol's descriptor is set to the low 16
5228 bits of this expression.
5231 An absolute expression which becomes the symbol's value.
5234 If a warning is detected while reading a @code{.stabd}, @code{.stabn},
5235 or @code{.stabs} statement, the symbol has probably already been created;
5236 you get a half-formed symbol in your object file. This is
5237 compatible with earlier assemblers!
5240 @cindex @code{stabd} directive
5241 @item .stabd @var{type} , @var{other} , @var{desc}
5243 The ``name'' of the symbol generated is not even an empty string.
5244 It is a null pointer, for compatibility. Older assemblers used a
5245 null pointer so they didn't waste space in object files with empty
5248 The symbol's value is set to the location counter,
5249 relocatably. When your program is linked, the value of this symbol
5250 is the address of the location counter when the @code{.stabd} was
5253 @cindex @code{stabn} directive
5254 @item .stabn @var{type} , @var{other} , @var{desc} , @var{value}
5255 The name of the symbol is set to the empty string @code{""}.
5257 @cindex @code{stabs} directive
5258 @item .stabs @var{string} , @var{type} , @var{other} , @var{desc} , @var{value}
5259 All five fields are specified.
5265 @section @code{.string} "@var{str}"
5267 @cindex string, copying to object file
5268 @cindex @code{string} directive
5270 Copy the characters in @var{str} to the object file. You may specify more than
5271 one string to copy, separated by commas. Unless otherwise specified for a
5272 particular machine, the assembler marks the end of each string with a 0 byte.
5273 You can use any of the escape sequences described in @ref{Strings,,Strings}.
5276 @section @code{.struct @var{expression}}
5278 @cindex @code{struct} directive
5279 Switch to the absolute section, and set the section offset to @var{expression},
5280 which must be an absolute expression. You might use this as follows:
5289 This would define the symbol @code{field1} to have the value 0, the symbol
5290 @code{field2} to have the value 4, and the symbol @code{field3} to have the
5291 value 8. Assembly would be left in the absolute section, and you would need to
5292 use a @code{.section} directive of some sort to change to some other section
5293 before further assembly.
5297 @section @code{.subsection @var{name}}
5299 @cindex @code{.subsection} directive
5300 @cindex Section Stack
5301 This is one of the ELF section stack manipulation directives. The others are
5302 @code{.section} (@pxref{Section}), @code{.pushsection} (@pxref{PushSection}),
5303 @code{.popsection} (@pxref{PopSection}), and @code{.previous}
5306 This directive replaces the current subsection with @code{name}. The current
5307 section is not changed. The replaced subsection is put onto the section stack
5308 in place of the then current top of stack subsection.
5313 @section @code{.symver}
5314 @cindex @code{symver} directive
5315 @cindex symbol versioning
5316 @cindex versions of symbols
5317 Use the @code{.symver} directive to bind symbols to specific version nodes
5318 within a source file. This is only supported on ELF platforms, and is
5319 typically used when assembling files to be linked into a shared library.
5320 There are cases where it may make sense to use this in objects to be bound
5321 into an application itself so as to override a versioned symbol from a
5324 For ELF targets, the @code{.symver} directive can be used like this:
5326 .symver @var{name}, @var{name2@@nodename}
5328 If the symbol @var{name} is defined within the file
5329 being assembled, the @code{.symver} directive effectively creates a symbol
5330 alias with the name @var{name2@@nodename}, and in fact the main reason that we
5331 just don't try and create a regular alias is that the @var{@@} character isn't
5332 permitted in symbol names. The @var{name2} part of the name is the actual name
5333 of the symbol by which it will be externally referenced. The name @var{name}
5334 itself is merely a name of convenience that is used so that it is possible to
5335 have definitions for multiple versions of a function within a single source
5336 file, and so that the compiler can unambiguously know which version of a
5337 function is being mentioned. The @var{nodename} portion of the alias should be
5338 the name of a node specified in the version script supplied to the linker when
5339 building a shared library. If you are attempting to override a versioned
5340 symbol from a shared library, then @var{nodename} should correspond to the
5341 nodename of the symbol you are trying to override.
5343 If the symbol @var{name} is not defined within the file being assembled, all
5344 references to @var{name} will be changed to @var{name2@@nodename}. If no
5345 reference to @var{name} is made, @var{name2@@nodename} will be removed from the
5348 Another usage of the @code{.symver} directive is:
5350 .symver @var{name}, @var{name2@@@@nodename}
5352 In this case, the symbol @var{name} must exist and be defined within
5353 the file being assembled. It is similar to @var{name2@@nodename}. The
5354 difference is @var{name2@@@@nodename} will also be used to resolve
5355 references to @var{name2} by the linker.
5357 The third usage of the @code{.symver} directive is:
5359 .symver @var{name}, @var{name2@@@@@@nodename}
5361 When @var{name} is not defined within the
5362 file being assembled, it is treated as @var{name2@@nodename}. When
5363 @var{name} is defined within the file being assembled, the symbol
5364 name, @var{name}, will be changed to @var{name2@@@@nodename}.
5369 @section @code{.tag @var{structname}}
5371 @cindex COFF structure debugging
5372 @cindex structure debugging, COFF
5373 @cindex @code{tag} directive
5374 This directive is generated by compilers to include auxiliary debugging
5375 information in the symbol table. It is only permitted inside
5376 @code{.def}/@code{.endef} pairs. Tags are used to link structure
5377 definitions in the symbol table with instances of those structures.
5380 @samp{.tag} is only used when generating COFF format output; when
5381 @command{@value{AS}} is generating @code{b.out}, it accepts this directive but
5387 @section @code{.text @var{subsection}}
5389 @cindex @code{text} directive
5390 Tells @command{@value{AS}} to assemble the following statements onto the end of
5391 the text subsection numbered @var{subsection}, which is an absolute
5392 expression. If @var{subsection} is omitted, subsection number zero
5396 @section @code{.title "@var{heading}"}
5398 @cindex @code{title} directive
5399 @cindex listing control: title line
5400 Use @var{heading} as the title (second line, immediately after the
5401 source file name and pagenumber) when generating assembly listings.
5403 This directive affects subsequent pages, as well as the current page if
5404 it appears within ten lines of the top of a page.
5407 @section @code{.type @var{int}} (COFF version)
5409 @cindex COFF symbol type
5410 @cindex symbol type, COFF
5411 @cindex @code{type} directive
5412 This directive, permitted only within @code{.def}/@code{.endef} pairs,
5413 records the integer @var{int} as the type attribute of a symbol table entry.
5416 @samp{.type} is associated only with COFF format output; when
5417 @command{@value{AS}} is configured for @code{b.out} output, it accepts this
5418 directive but ignores it.
5421 @section @code{.type @var{name} , @var{type description}} (ELF version)
5423 @cindex ELF symbol type
5424 @cindex symbol type, ELF
5425 @cindex @code{type} directive
5426 This directive is used to set the type of symbol @var{name} to be either a
5427 function symbol or an object symbol. There are five different syntaxes
5428 supported for the @var{type description} field, in order to provide
5429 compatibility with various other assemblers. The syntaxes supported are:
5432 .type <name>,#function
5433 .type <name>,#object
5435 .type <name>,@@function
5436 .type <name>,@@object
5438 .type <name>,%function
5439 .type <name>,%object
5441 .type <name>,"function"
5442 .type <name>,"object"
5444 .type <name> STT_FUNCTION
5445 .type <name> STT_OBJECT
5449 @section @code{.uleb128 @var{expressions}}
5451 @cindex @code{uleb128} directive
5452 @var{uleb128} stands for ``unsigned little endian base 128.'' This is a
5453 compact, variable length representation of numbers used by the DWARF
5454 symbolic debugging format. @xref{Sleb128,@code{.sleb128}}.
5458 @section @code{.val @var{addr}}
5460 @cindex @code{val} directive
5461 @cindex COFF value attribute
5462 @cindex value attribute, COFF
5463 This directive, permitted only within @code{.def}/@code{.endef} pairs,
5464 records the address @var{addr} as the value attribute of a symbol table
5468 @samp{.val} is used only for COFF output; when @command{@value{AS}} is
5469 configured for @code{b.out}, it accepts this directive but ignores it.
5475 @section @code{.version "@var{string}"}
5477 @cindex @code{.version}
5478 This directive creates a @code{.note} section and places into it an ELF
5479 formatted note of type NT_VERSION. The note's name is set to @code{string}.
5484 @section @code{.vtable_entry @var{table}, @var{offset}}
5486 @cindex @code{.vtable_entry}
5487 This directive finds or creates a symbol @code{table} and creates a
5488 @code{VTABLE_ENTRY} relocation for it with an addend of @code{offset}.
5491 @section @code{.vtable_inherit @var{child}, @var{parent}}
5493 @cindex @code{.vtable_inherit}
5494 This directive finds the symbol @code{child} and finds or creates the symbol
5495 @code{parent} and then creates a @code{VTABLE_INHERIT} relocation for the
5496 parent whose addend is the value of the child symbol. As a special case the
5497 parent name of @code{0} is treated as refering the @code{*ABS*} section.
5502 @section @code{.weak @var{names}}
5504 @cindex @code{.weak}
5505 This directive sets the weak attribute on the comma separated list of symbol
5506 @code{names}. If the symbols do not already exist, they will be created.
5510 @section @code{.word @var{expressions}}
5512 @cindex @code{word} directive
5513 This directive expects zero or more @var{expressions}, of any section,
5514 separated by commas.
5517 For each expression, @command{@value{AS}} emits a 32-bit number.
5520 For each expression, @command{@value{AS}} emits a 16-bit number.
5525 The size of the number emitted, and its byte order,
5526 depend on what target computer the assembly is for.
5529 @c on amd29k, i960, sparc the "special treatment to support compilers" doesn't
5530 @c happen---32-bit addressability, period; no long/short jumps.
5531 @ifset DIFF-TBL-KLUGE
5532 @cindex difference tables altered
5533 @cindex altered difference tables
5535 @emph{Warning: Special Treatment to support Compilers}
5539 Machines with a 32-bit address space, but that do less than 32-bit
5540 addressing, require the following special treatment. If the machine of
5541 interest to you does 32-bit addressing (or doesn't require it;
5542 @pxref{Machine Dependencies}), you can ignore this issue.
5545 In order to assemble compiler output into something that works,
5546 @command{@value{AS}} occasionally does strange things to @samp{.word} directives.
5547 Directives of the form @samp{.word sym1-sym2} are often emitted by
5548 compilers as part of jump tables. Therefore, when @command{@value{AS}} assembles a
5549 directive of the form @samp{.word sym1-sym2}, and the difference between
5550 @code{sym1} and @code{sym2} does not fit in 16 bits, @command{@value{AS}}
5551 creates a @dfn{secondary jump table}, immediately before the next label.
5552 This secondary jump table is preceded by a short-jump to the
5553 first byte after the secondary table. This short-jump prevents the flow
5554 of control from accidentally falling into the new table. Inside the
5555 table is a long-jump to @code{sym2}. The original @samp{.word}
5556 contains @code{sym1} minus the address of the long-jump to
5559 If there were several occurrences of @samp{.word sym1-sym2} before the
5560 secondary jump table, all of them are adjusted. If there was a
5561 @samp{.word sym3-sym4}, that also did not fit in sixteen bits, a
5562 long-jump to @code{sym4} is included in the secondary jump table,
5563 and the @code{.word} directives are adjusted to contain @code{sym3}
5564 minus the address of the long-jump to @code{sym4}; and so on, for as many
5565 entries in the original jump table as necessary.
5568 @emph{This feature may be disabled by compiling @command{@value{AS}} with the
5569 @samp{-DWORKING_DOT_WORD} option.} This feature is likely to confuse
5570 assembly language programmers.
5573 @c end DIFF-TBL-KLUGE
5576 @section Deprecated Directives
5578 @cindex deprecated directives
5579 @cindex obsolescent directives
5580 One day these directives won't work.
5581 They are included for compatibility with older assemblers.
5588 @node Machine Dependencies
5589 @chapter Machine Dependent Features
5591 @cindex machine dependencies
5592 The machine instruction sets are (almost by definition) different on
5593 each machine where @command{@value{AS}} runs. Floating point representations
5594 vary as well, and @command{@value{AS}} often supports a few additional
5595 directives or command-line options for compatibility with other
5596 assemblers on a particular platform. Finally, some versions of
5597 @command{@value{AS}} support special pseudo-instructions for branch
5600 This chapter discusses most of these differences, though it does not
5601 include details on any machine's instruction set. For details on that
5602 subject, see the hardware manufacturer's manual.
5606 * AMD29K-Dependent:: AMD 29K Dependent Features
5609 * Alpha-Dependent:: Alpha Dependent Features
5612 * ARC-Dependent:: ARC Dependent Features
5615 * ARM-Dependent:: ARM Dependent Features
5618 * CRIS-Dependent:: CRIS Dependent Features
5621 * D10V-Dependent:: D10V Dependent Features
5624 * D30V-Dependent:: D30V Dependent Features
5627 * H8/300-Dependent:: Hitachi H8/300 Dependent Features
5630 * H8/500-Dependent:: Hitachi H8/500 Dependent Features
5633 * HPPA-Dependent:: HPPA Dependent Features
5636 * ESA/390-Dependent:: IBM ESA/390 Dependent Features
5639 * i386-Dependent:: Intel 80386 and AMD x86-64 Dependent Features
5642 * i860-Dependent:: Intel 80860 Dependent Features
5645 * i960-Dependent:: Intel 80960 Dependent Features
5648 * M32R-Dependent:: M32R Dependent Features
5651 * M68K-Dependent:: M680x0 Dependent Features
5654 * M68HC11-Dependent:: M68HC11 and 68HC12 Dependent Features
5657 * M88K-Dependent:: M880x0 Dependent Features
5660 * MIPS-Dependent:: MIPS Dependent Features
5663 * MMIX-Dependent:: MMIX Dependent Features
5666 * SH-Dependent:: Hitachi SH Dependent Features
5667 * SH64-Dependent:: Hitachi SH64 Dependent Features
5670 * PDP-11-Dependent:: PDP-11 Dependent Features
5673 * PJ-Dependent:: picoJava Dependent Features
5676 * PPC-Dependent:: PowerPC Dependent Features
5679 * Sparc-Dependent:: SPARC Dependent Features
5682 * TIC54X-Dependent:: TI TMS320C54x Dependent Features
5685 * V850-Dependent:: V850 Dependent Features
5688 * Z8000-Dependent:: Z8000 Dependent Features
5691 * Vax-Dependent:: VAX Dependent Features
5698 @c The following major nodes are *sections* in the GENERIC version, *chapters*
5699 @c in single-cpu versions. This is mainly achieved by @lowersections. There is a
5700 @c peculiarity: to preserve cross-references, there must be a node called
5701 @c "Machine Dependencies". Hence the conditional nodenames in each
5702 @c major node below. Node defaulting in makeinfo requires adjacency of
5703 @c node and sectioning commands; hence the repetition of @chapter BLAH
5704 @c in both conditional blocks.
5707 @include c-a29k.texi
5711 @include c-alpha.texi
5723 @include c-cris.texi
5728 @node Machine Dependencies
5729 @chapter Machine Dependent Features
5731 The machine instruction sets are different on each Hitachi chip family,
5732 and there are also some syntax differences among the families. This
5733 chapter describes the specific @command{@value{AS}} features for each
5737 * H8/300-Dependent:: Hitachi H8/300 Dependent Features
5738 * H8/500-Dependent:: Hitachi H8/500 Dependent Features
5739 * SH-Dependent:: Hitachi SH Dependent Features
5746 @include c-d10v.texi
5750 @include c-d30v.texi
5754 @include c-h8300.texi
5758 @include c-h8500.texi
5762 @include c-hppa.texi
5766 @include c-i370.texi
5770 @include c-i386.texi
5774 @include c-i860.texi
5778 @include c-i960.texi
5782 @include c-ia64.texi
5786 @include c-m32r.texi
5790 @include c-m68k.texi
5794 @include c-m68hc11.texi
5798 @include c-m88k.texi
5802 @include c-mips.texi
5806 @include c-mmix.texi
5810 @include c-ns32k.texi
5814 @include c-pdp11.texi
5827 @include c-sh64.texi
5831 @include c-sparc.texi
5835 @include c-tic54x.texi
5847 @include c-v850.texi
5851 @c reverse effect of @down at top of generic Machine-Dep chapter
5855 @node Reporting Bugs
5856 @chapter Reporting Bugs
5857 @cindex bugs in assembler
5858 @cindex reporting bugs in assembler
5860 Your bug reports play an essential role in making @command{@value{AS}} reliable.
5862 Reporting a bug may help you by bringing a solution to your problem, or it may
5863 not. But in any case the principal function of a bug report is to help the
5864 entire community by making the next version of @command{@value{AS}} work better.
5865 Bug reports are your contribution to the maintenance of @command{@value{AS}}.
5867 In order for a bug report to serve its purpose, you must include the
5868 information that enables us to fix the bug.
5871 * Bug Criteria:: Have you found a bug?
5872 * Bug Reporting:: How to report bugs
5876 @section Have you found a bug?
5877 @cindex bug criteria
5879 If you are not sure whether you have found a bug, here are some guidelines:
5882 @cindex fatal signal
5883 @cindex assembler crash
5884 @cindex crash of assembler
5886 If the assembler gets a fatal signal, for any input whatever, that is a
5887 @command{@value{AS}} bug. Reliable assemblers never crash.
5889 @cindex error on valid input
5891 If @command{@value{AS}} produces an error message for valid input, that is a bug.
5893 @cindex invalid input
5895 If @command{@value{AS}} does not produce an error message for invalid input, that
5896 is a bug. However, you should note that your idea of ``invalid input'' might
5897 be our idea of ``an extension'' or ``support for traditional practice''.
5900 If you are an experienced user of assemblers, your suggestions for improvement
5901 of @command{@value{AS}} are welcome in any case.
5905 @section How to report bugs
5907 @cindex assembler bugs, reporting
5909 A number of companies and individuals offer support for @sc{gnu} products. If
5910 you obtained @command{@value{AS}} from a support organization, we recommend you
5911 contact that organization first.
5913 You can find contact information for many support companies and
5914 individuals in the file @file{etc/SERVICE} in the @sc{gnu} Emacs
5917 In any event, we also recommend that you send bug reports for @command{@value{AS}}
5918 to @samp{bug-binutils@@gnu.org}.
5920 The fundamental principle of reporting bugs usefully is this:
5921 @strong{report all the facts}. If you are not sure whether to state a
5922 fact or leave it out, state it!
5924 Often people omit facts because they think they know what causes the problem
5925 and assume that some details do not matter. Thus, you might assume that the
5926 name of a symbol you use in an example does not matter. Well, probably it does
5927 not, but one cannot be sure. Perhaps the bug is a stray memory reference which
5928 happens to fetch from the location where that name is stored in memory;
5929 perhaps, if the name were different, the contents of that location would fool
5930 the assembler into doing the right thing despite the bug. Play it safe and
5931 give a specific, complete example. That is the easiest thing for you to do,
5932 and the most helpful.
5934 Keep in mind that the purpose of a bug report is to enable us to fix the bug if
5935 it is new to us. Therefore, always write your bug reports on the assumption
5936 that the bug has not been reported previously.
5938 Sometimes people give a few sketchy facts and ask, ``Does this ring a
5939 bell?'' Those bug reports are useless, and we urge everyone to
5940 @emph{refuse to respond to them} except to chide the sender to report
5943 To enable us to fix the bug, you should include all these things:
5947 The version of @command{@value{AS}}. @command{@value{AS}} announces it if you start
5948 it with the @samp{--version} argument.
5950 Without this, we will not know whether there is any point in looking for
5951 the bug in the current version of @command{@value{AS}}.
5954 Any patches you may have applied to the @command{@value{AS}} source.
5957 The type of machine you are using, and the operating system name and
5961 What compiler (and its version) was used to compile @command{@value{AS}}---e.g.
5965 The command arguments you gave the assembler to assemble your example and
5966 observe the bug. To guarantee you will not omit something important, list them
5967 all. A copy of the Makefile (or the output from make) is sufficient.
5969 If we were to try to guess the arguments, we would probably guess wrong
5970 and then we might not encounter the bug.
5973 A complete input file that will reproduce the bug. If the bug is observed when
5974 the assembler is invoked via a compiler, send the assembler source, not the
5975 high level language source. Most compilers will produce the assembler source
5976 when run with the @samp{-S} option. If you are using @code{@value{GCC}}, use
5977 the options @samp{-v --save-temps}; this will save the assembler source in a
5978 file with an extension of @file{.s}, and also show you exactly how
5979 @command{@value{AS}} is being run.
5982 A description of what behavior you observe that you believe is
5983 incorrect. For example, ``It gets a fatal signal.''
5985 Of course, if the bug is that @command{@value{AS}} gets a fatal signal, then we
5986 will certainly notice it. But if the bug is incorrect output, we might not
5987 notice unless it is glaringly wrong. You might as well not give us a chance to
5990 Even if the problem you experience is a fatal signal, you should still say so
5991 explicitly. Suppose something strange is going on, such as, your copy of
5992 @command{@value{AS}} is out of synch, or you have encountered a bug in the C
5993 library on your system. (This has happened!) Your copy might crash and ours
5994 would not. If you told us to expect a crash, then when ours fails to crash, we
5995 would know that the bug was not happening for us. If you had not told us to
5996 expect a crash, then we would not be able to draw any conclusion from our
6000 If you wish to suggest changes to the @command{@value{AS}} source, send us context
6001 diffs, as generated by @code{diff} with the @samp{-u}, @samp{-c}, or @samp{-p}
6002 option. Always send diffs from the old file to the new file. If you even
6003 discuss something in the @command{@value{AS}} source, refer to it by context, not
6006 The line numbers in our development sources will not match those in your
6007 sources. Your line numbers would convey no useful information to us.
6010 Here are some things that are not necessary:
6014 A description of the envelope of the bug.
6016 Often people who encounter a bug spend a lot of time investigating
6017 which changes to the input file will make the bug go away and which
6018 changes will not affect it.
6020 This is often time consuming and not very useful, because the way we
6021 will find the bug is by running a single example under the debugger
6022 with breakpoints, not by pure deduction from a series of examples.
6023 We recommend that you save your time for something else.
6025 Of course, if you can find a simpler example to report @emph{instead}
6026 of the original one, that is a convenience for us. Errors in the
6027 output will be easier to spot, running under the debugger will take
6028 less time, and so on.
6030 However, simplification is not vital; if you do not want to do this,
6031 report the bug anyway and send us the entire test case you used.
6034 A patch for the bug.
6036 A patch for the bug does help us if it is a good one. But do not omit
6037 the necessary information, such as the test case, on the assumption that
6038 a patch is all we need. We might see problems with your patch and decide
6039 to fix the problem another way, or we might not understand it at all.
6041 Sometimes with a program as complicated as @command{@value{AS}} it is very hard to
6042 construct an example that will make the program follow a certain path through
6043 the code. If you do not send us the example, we will not be able to construct
6044 one, so we will not be able to verify that the bug is fixed.
6046 And if we cannot understand what bug you are trying to fix, or why your
6047 patch should be an improvement, we will not install it. A test case will
6048 help us to understand.
6051 A guess about what the bug is or what it depends on.
6053 Such guesses are usually wrong. Even we cannot guess right about such
6054 things without first using the debugger to find the facts.
6057 @node Acknowledgements
6058 @chapter Acknowledgements
6060 If you have contributed to @command{@value{AS}} and your name isn't listed here,
6061 it is not meant as a slight. We just don't know about it. Send mail to the
6062 maintainer, and we'll correct the situation. Currently
6064 the maintainer is Ken Raeburn (email address @code{raeburn@@cygnus.com}).
6066 Dean Elsner wrote the original @sc{gnu} assembler for the VAX.@footnote{Any
6069 Jay Fenlason maintained GAS for a while, adding support for GDB-specific debug
6070 information and the 68k series machines, most of the preprocessing pass, and
6071 extensive changes in @file{messages.c}, @file{input-file.c}, @file{write.c}.
6073 K. Richard Pixley maintained GAS for a while, adding various enhancements and
6074 many bug fixes, including merging support for several processors, breaking GAS
6075 up to handle multiple object file format back ends (including heavy rewrite,
6076 testing, an integration of the coff and b.out back ends), adding configuration
6077 including heavy testing and verification of cross assemblers and file splits
6078 and renaming, converted GAS to strictly ANSI C including full prototypes, added
6079 support for m680[34]0 and cpu32, did considerable work on i960 including a COFF
6080 port (including considerable amounts of reverse engineering), a SPARC opcode
6081 file rewrite, DECstation, rs6000, and hp300hpux host ports, updated ``know''
6082 assertions and made them work, much other reorganization, cleanup, and lint.
6084 Ken Raeburn wrote the high-level BFD interface code to replace most of the code
6085 in format-specific I/O modules.
6087 The original VMS support was contributed by David L. Kashtan. Eric Youngdale
6088 has done much work with it since.
6090 The Intel 80386 machine description was written by Eliot Dresselhaus.
6092 Minh Tran-Le at IntelliCorp contributed some AIX 386 support.
6094 The Motorola 88k machine description was contributed by Devon Bowen of Buffalo
6095 University and Torbjorn Granlund of the Swedish Institute of Computer Science.
6097 Keith Knowles at the Open Software Foundation wrote the original MIPS back end
6098 (@file{tc-mips.c}, @file{tc-mips.h}), and contributed Rose format support
6099 (which hasn't been merged in yet). Ralph Campbell worked with the MIPS code to
6100 support a.out format.
6102 Support for the Zilog Z8k and Hitachi H8/300 and H8/500 processors (tc-z8k,
6103 tc-h8300, tc-h8500), and IEEE 695 object file format (obj-ieee), was written by
6104 Steve Chamberlain of Cygnus Support. Steve also modified the COFF back end to
6105 use BFD for some low-level operations, for use with the H8/300 and AMD 29k
6108 John Gilmore built the AMD 29000 support, added @code{.include} support, and
6109 simplified the configuration of which versions accept which directives. He
6110 updated the 68k machine description so that Motorola's opcodes always produced
6111 fixed-size instructions (e.g. @code{jsr}), while synthetic instructions
6112 remained shrinkable (@code{jbsr}). John fixed many bugs, including true tested
6113 cross-compilation support, and one bug in relaxation that took a week and
6114 required the proverbial one-bit fix.
6116 Ian Lance Taylor of Cygnus Support merged the Motorola and MIT syntax for the
6117 68k, completed support for some COFF targets (68k, i386 SVR3, and SCO Unix),
6118 added support for MIPS ECOFF and ELF targets, wrote the initial RS/6000 and
6119 PowerPC assembler, and made a few other minor patches.
6121 Steve Chamberlain made @command{@value{AS}} able to generate listings.
6123 Hewlett-Packard contributed support for the HP9000/300.
6125 Jeff Law wrote GAS and BFD support for the native HPPA object format (SOM)
6126 along with a fairly extensive HPPA testsuite (for both SOM and ELF object
6127 formats). This work was supported by both the Center for Software Science at
6128 the University of Utah and Cygnus Support.
6130 Support for ELF format files has been worked on by Mark Eichin of Cygnus
6131 Support (original, incomplete implementation for SPARC), Pete Hoogenboom and
6132 Jeff Law at the University of Utah (HPPA mainly), Michael Meissner of the Open
6133 Software Foundation (i386 mainly), and Ken Raeburn of Cygnus Support (sparc,
6134 and some initial 64-bit support).
6136 Linas Vepstas added GAS support for the ESA/390 "IBM 370" architecture.
6138 Richard Henderson rewrote the Alpha assembler. Klaus Kaempf wrote GAS and BFD
6139 support for openVMS/Alpha.
6141 Timothy Wall, Michael Hayes, and Greg Smart contributed to the various tic*
6144 Several engineers at Cygnus Support have also provided many small bug fixes and
6145 configuration enhancements.
6147 Many others have contributed large or small bugfixes and enhancements. If
6148 you have contributed significant work and are not mentioned on this list, and
6149 want to be, let us know. Some of the history has been lost; we are not
6150 intentionally leaving anyone out.
6152 @node GNU Free Documentation License
6153 @chapter GNU Free Documentation License
6155 GNU Free Documentation License
6157 Version 1.1, March 2000
6159 Copyright (C) 2000 Free Software Foundation, Inc.
6160 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
6162 Everyone is permitted to copy and distribute verbatim copies
6163 of this license document, but changing it is not allowed.
6168 The purpose of this License is to make a manual, textbook, or other
6169 written document "free" in the sense of freedom: to assure everyone
6170 the effective freedom to copy and redistribute it, with or without
6171 modifying it, either commercially or noncommercially. Secondarily,
6172 this License preserves for the author and publisher a way to get
6173 credit for their work, while not being considered responsible for
6174 modifications made by others.
6176 This License is a kind of "copyleft", which means that derivative
6177 works of the document must themselves be free in the same sense. It
6178 complements the GNU General Public License, which is a copyleft
6179 license designed for free software.
6181 We have designed this License in order to use it for manuals for free
6182 software, because free software needs free documentation: a free
6183 program should come with manuals providing the same freedoms that the
6184 software does. But this License is not limited to software manuals;
6185 it can be used for any textual work, regardless of subject matter or
6186 whether it is published as a printed book. We recommend this License
6187 principally for works whose purpose is instruction or reference.
6190 1. APPLICABILITY AND DEFINITIONS
6192 This License applies to any manual or other work that contains a
6193 notice placed by the copyright holder saying it can be distributed
6194 under the terms of this License. The "Document", below, refers to any
6195 such manual or work. Any member of the public is a licensee, and is
6198 A "Modified Version" of the Document means any work containing the
6199 Document or a portion of it, either copied verbatim, or with
6200 modifications and/or translated into another language.
6202 A "Secondary Section" is a named appendix or a front-matter section of
6203 the Document that deals exclusively with the relationship of the
6204 publishers or authors of the Document to the Document's overall subject
6205 (or to related matters) and contains nothing that could fall directly
6206 within that overall subject. (For example, if the Document is in part a
6207 textbook of mathematics, a Secondary Section may not explain any
6208 mathematics.) The relationship could be a matter of historical
6209 connection with the subject or with related matters, or of legal,
6210 commercial, philosophical, ethical or political position regarding
6213 The "Invariant Sections" are certain Secondary Sections whose titles
6214 are designated, as being those of Invariant Sections, in the notice
6215 that says that the Document is released under this License.
6217 The "Cover Texts" are certain short passages of text that are listed,
6218 as Front-Cover Texts or Back-Cover Texts, in the notice that says that
6219 the Document is released under this License.
6221 A "Transparent" copy of the Document means a machine-readable copy,
6222 represented in a format whose specification is available to the
6223 general public, whose contents can be viewed and edited directly and
6224 straightforwardly with generic text editors or (for images composed of
6225 pixels) generic paint programs or (for drawings) some widely available
6226 drawing editor, and that is suitable for input to text formatters or
6227 for automatic translation to a variety of formats suitable for input
6228 to text formatters. A copy made in an otherwise Transparent file
6229 format whose markup has been designed to thwart or discourage
6230 subsequent modification by readers is not Transparent. A copy that is
6231 not "Transparent" is called "Opaque".
6233 Examples of suitable formats for Transparent copies include plain
6234 ASCII without markup, Texinfo input format, LaTeX input format, SGML
6235 or XML using a publicly available DTD, and standard-conforming simple
6236 HTML designed for human modification. Opaque formats include
6237 PostScript, PDF, proprietary formats that can be read and edited only
6238 by proprietary word processors, SGML or XML for which the DTD and/or
6239 processing tools are not generally available, and the
6240 machine-generated HTML produced by some word processors for output
6243 The "Title Page" means, for a printed book, the title page itself,
6244 plus such following pages as are needed to hold, legibly, the material
6245 this License requires to appear in the title page. For works in
6246 formats which do not have any title page as such, "Title Page" means
6247 the text near the most prominent appearance of the work's title,
6248 preceding the beginning of the body of the text.
6253 You may copy and distribute the Document in any medium, either
6254 commercially or noncommercially, provided that this License, the
6255 copyright notices, and the license notice saying this License applies
6256 to the Document are reproduced in all copies, and that you add no other
6257 conditions whatsoever to those of this License. You may not use
6258 technical measures to obstruct or control the reading or further
6259 copying of the copies you make or distribute. However, you may accept
6260 compensation in exchange for copies. If you distribute a large enough
6261 number of copies you must also follow the conditions in section 3.
6263 You may also lend copies, under the same conditions stated above, and
6264 you may publicly display copies.
6267 3. COPYING IN QUANTITY
6269 If you publish printed copies of the Document numbering more than 100,
6270 and the Document's license notice requires Cover Texts, you must enclose
6271 the copies in covers that carry, clearly and legibly, all these Cover
6272 Texts: Front-Cover Texts on the front cover, and Back-Cover Texts on
6273 the back cover. Both covers must also clearly and legibly identify
6274 you as the publisher of these copies. The front cover must present
6275 the full title with all words of the title equally prominent and
6276 visible. You may add other material on the covers in addition.
6277 Copying with changes limited to the covers, as long as they preserve
6278 the title of the Document and satisfy these conditions, can be treated
6279 as verbatim copying in other respects.
6281 If the required texts for either cover are too voluminous to fit
6282 legibly, you should put the first ones listed (as many as fit
6283 reasonably) on the actual cover, and continue the rest onto adjacent
6286 If you publish or distribute Opaque copies of the Document numbering
6287 more than 100, you must either include a machine-readable Transparent
6288 copy along with each Opaque copy, or state in or with each Opaque copy
6289 a publicly-accessible computer-network location containing a complete
6290 Transparent copy of the Document, free of added material, which the
6291 general network-using public has access to download anonymously at no
6292 charge using public-standard network protocols. If you use the latter
6293 option, you must take reasonably prudent steps, when you begin
6294 distribution of Opaque copies in quantity, to ensure that this
6295 Transparent copy will remain thus accessible at the stated location
6296 until at least one year after the last time you distribute an Opaque
6297 copy (directly or through your agents or retailers) of that edition to
6300 It is requested, but not required, that you contact the authors of the
6301 Document well before redistributing any large number of copies, to give
6302 them a chance to provide you with an updated version of the Document.
6307 You may copy and distribute a Modified Version of the Document under
6308 the conditions of sections 2 and 3 above, provided that you release
6309 the Modified Version under precisely this License, with the Modified
6310 Version filling the role of the Document, thus licensing distribution
6311 and modification of the Modified Version to whoever possesses a copy
6312 of it. In addition, you must do these things in the Modified Version:
6314 A. Use in the Title Page (and on the covers, if any) a title distinct
6315 from that of the Document, and from those of previous versions
6316 (which should, if there were any, be listed in the History section
6317 of the Document). You may use the same title as a previous version
6318 if the original publisher of that version gives permission.
6319 B. List on the Title Page, as authors, one or more persons or entities
6320 responsible for authorship of the modifications in the Modified
6321 Version, together with at least five of the principal authors of the
6322 Document (all of its principal authors, if it has less than five).
6323 C. State on the Title page the name of the publisher of the
6324 Modified Version, as the publisher.
6325 D. Preserve all the copyright notices of the Document.
6326 E. Add an appropriate copyright notice for your modifications
6327 adjacent to the other copyright notices.
6328 F. Include, immediately after the copyright notices, a license notice
6329 giving the public permission to use the Modified Version under the
6330 terms of this License, in the form shown in the Addendum below.
6331 G. Preserve in that license notice the full lists of Invariant Sections
6332 and required Cover Texts given in the Document's license notice.
6333 H. Include an unaltered copy of this License.
6334 I. Preserve the section entitled "History", and its title, and add to
6335 it an item stating at least the title, year, new authors, and
6336 publisher of the Modified Version as given on the Title Page. If
6337 there is no section entitled "History" in the Document, create one
6338 stating the title, year, authors, and publisher of the Document as
6339 given on its Title Page, then add an item describing the Modified
6340 Version as stated in the previous sentence.
6341 J. Preserve the network location, if any, given in the Document for
6342 public access to a Transparent copy of the Document, and likewise
6343 the network locations given in the Document for previous versions
6344 it was based on. These may be placed in the "History" section.
6345 You may omit a network location for a work that was published at
6346 least four years before the Document itself, or if the original
6347 publisher of the version it refers to gives permission.
6348 K. In any section entitled "Acknowledgements" or "Dedications",
6349 preserve the section's title, and preserve in the section all the
6350 substance and tone of each of the contributor acknowledgements
6351 and/or dedications given therein.
6352 L. Preserve all the Invariant Sections of the Document,
6353 unaltered in their text and in their titles. Section numbers
6354 or the equivalent are not considered part of the section titles.
6355 M. Delete any section entitled "Endorsements". Such a section
6356 may not be included in the Modified Version.
6357 N. Do not retitle any existing section as "Endorsements"
6358 or to conflict in title with any Invariant Section.
6360 If the Modified Version includes new front-matter sections or
6361 appendices that qualify as Secondary Sections and contain no material
6362 copied from the Document, you may at your option designate some or all
6363 of these sections as invariant. To do this, add their titles to the
6364 list of Invariant Sections in the Modified Version's license notice.
6365 These titles must be distinct from any other section titles.
6367 You may add a section entitled "Endorsements", provided it contains
6368 nothing but endorsements of your Modified Version by various
6369 parties--for example, statements of peer review or that the text has
6370 been approved by an organization as the authoritative definition of a
6373 You may add a passage of up to five words as a Front-Cover Text, and a
6374 passage of up to 25 words as a Back-Cover Text, to the end of the list
6375 of Cover Texts in the Modified Version. Only one passage of
6376 Front-Cover Text and one of Back-Cover Text may be added by (or
6377 through arrangements made by) any one entity. If the Document already
6378 includes a cover text for the same cover, previously added by you or
6379 by arrangement made by the same entity you are acting on behalf of,
6380 you may not add another; but you may replace the old one, on explicit
6381 permission from the previous publisher that added the old one.
6383 The author(s) and publisher(s) of the Document do not by this License
6384 give permission to use their names for publicity for or to assert or
6385 imply endorsement of any Modified Version.
6388 5. COMBINING DOCUMENTS
6390 You may combine the Document with other documents released under this
6391 License, under the terms defined in section 4 above for modified
6392 versions, provided that you include in the combination all of the
6393 Invariant Sections of all of the original documents, unmodified, and
6394 list them all as Invariant Sections of your combined work in its
6397 The combined work need only contain one copy of this License, and
6398 multiple identical Invariant Sections may be replaced with a single
6399 copy. If there are multiple Invariant Sections with the same name but
6400 different contents, make the title of each such section unique by
6401 adding at the end of it, in parentheses, the name of the original
6402 author or publisher of that section if known, or else a unique number.
6403 Make the same adjustment to the section titles in the list of
6404 Invariant Sections in the license notice of the combined work.
6406 In the combination, you must combine any sections entitled "History"
6407 in the various original documents, forming one section entitled
6408 "History"; likewise combine any sections entitled "Acknowledgements",
6409 and any sections entitled "Dedications". You must delete all sections
6410 entitled "Endorsements."
6413 6. COLLECTIONS OF DOCUMENTS
6415 You may make a collection consisting of the Document and other documents
6416 released under this License, and replace the individual copies of this
6417 License in the various documents with a single copy that is included in
6418 the collection, provided that you follow the rules of this License for
6419 verbatim copying of each of the documents in all other respects.
6421 You may extract a single document from such a collection, and distribute
6422 it individually under this License, provided you insert a copy of this
6423 License into the extracted document, and follow this License in all
6424 other respects regarding verbatim copying of that document.
6427 7. AGGREGATION WITH INDEPENDENT WORKS
6429 A compilation of the Document or its derivatives with other separate
6430 and independent documents or works, in or on a volume of a storage or
6431 distribution medium, does not as a whole count as a Modified Version
6432 of the Document, provided no compilation copyright is claimed for the
6433 compilation. Such a compilation is called an "aggregate", and this
6434 License does not apply to the other self-contained works thus compiled
6435 with the Document, on account of their being thus compiled, if they
6436 are not themselves derivative works of the Document.
6438 If the Cover Text requirement of section 3 is applicable to these
6439 copies of the Document, then if the Document is less than one quarter
6440 of the entire aggregate, the Document's Cover Texts may be placed on
6441 covers that surround only the Document within the aggregate.
6442 Otherwise they must appear on covers around the whole aggregate.
6447 Translation is considered a kind of modification, so you may
6448 distribute translations of the Document under the terms of section 4.
6449 Replacing Invariant Sections with translations requires special
6450 permission from their copyright holders, but you may include
6451 translations of some or all Invariant Sections in addition to the
6452 original versions of these Invariant Sections. You may include a
6453 translation of this License provided that you also include the
6454 original English version of this License. In case of a disagreement
6455 between the translation and the original English version of this
6456 License, the original English version will prevail.
6461 You may not copy, modify, sublicense, or distribute the Document except
6462 as expressly provided for under this License. Any other attempt to
6463 copy, modify, sublicense or distribute the Document is void, and will
6464 automatically terminate your rights under this License. However,
6465 parties who have received copies, or rights, from you under this
6466 License will not have their licenses terminated so long as such
6467 parties remain in full compliance.
6470 10. FUTURE REVISIONS OF THIS LICENSE
6472 The Free Software Foundation may publish new, revised versions
6473 of the GNU Free Documentation License from time to time. Such new
6474 versions will be similar in spirit to the present version, but may
6475 differ in detail to address new problems or concerns. See
6476 http://www.gnu.org/copyleft/.
6478 Each version of the License is given a distinguishing version number.
6479 If the Document specifies that a particular numbered version of this
6480 License "or any later version" applies to it, you have the option of
6481 following the terms and conditions either of that specified version or
6482 of any later version that has been published (not as a draft) by the
6483 Free Software Foundation. If the Document does not specify a version
6484 number of this License, you may choose any version ever published (not
6485 as a draft) by the Free Software Foundation.
6488 ADDENDUM: How to use this License for your documents
6490 To use this License in a document you have written, include a copy of
6491 the License in the document and put the following copyright and
6492 license notices just after the title page:
6495 Copyright (c) YEAR YOUR NAME.
6496 Permission is granted to copy, distribute and/or modify this document
6497 under the terms of the GNU Free Documentation License, Version 1.1
6498 or any later version published by the Free Software Foundation;
6499 with the Invariant Sections being LIST THEIR TITLES, with the
6500 Front-Cover Texts being LIST, and with the Back-Cover Texts being LIST.
6501 A copy of the license is included in the section entitled "GNU
6502 Free Documentation License".
6505 If you have no Invariant Sections, write "with no Invariant Sections"
6506 instead of saying which ones are invariant. If you have no
6507 Front-Cover Texts, write "no Front-Cover Texts" instead of
6508 "Front-Cover Texts being LIST"; likewise for Back-Cover Texts.
6510 If your document contains nontrivial examples of program code, we
6511 recommend releasing these examples in parallel under your choice of
6512 free software license, such as the GNU General Public License,
6513 to permit their use in free software.
projects / deliverable / binutils-gdb.git / blob