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
64 @c common OR combinations of conditions
84 @set abnormal-separator
88 @settitle Using @value{AS}
91 @settitle Using @value{AS} (@value{TARGET})
93 @setchapternewpage odd
98 @c WARE! Some of the machine-dependent sections contain tables of machine
99 @c instructions. Except in multi-column format, these tables look silly.
100 @c Unfortunately, Texinfo doesn't have a general-purpose multi-col format, so
101 @c the multi-col format is faked within @example sections.
103 @c Again unfortunately, the natural size that fits on a page, for these tables,
104 @c is different depending on whether or not smallbook is turned on.
105 @c This matters, because of order: text flow switches columns at each page
108 @c The format faked in this source works reasonably well for smallbook,
109 @c not well for the default large-page format. This manual expects that if you
110 @c turn on @smallbook, you will also uncomment the "@set SMALL" to enable the
111 @c tables in question. You can turn on one without the other at your
112 @c discretion, of course.
115 @c the insn tables look just as silly in info files regardless of smallbook,
116 @c might as well show 'em anyways.
122 * As: (as). The GNU assembler.
123 * Gas: (as). The GNU assembler.
132 This file documents the GNU Assembler "@value{AS}".
134 @c man begin COPYRIGHT
135 Copyright (C) 1991, 92, 93, 94, 95, 96, 97, 98, 99, 2000, 2001, 2002 Free Software Foundation, Inc.
137 Permission is granted to copy, distribute and/or modify this document
138 under the terms of the GNU Free Documentation License, Version 1.1
139 or any later version published by the Free Software Foundation;
140 with no Invariant Sections, with no Front-Cover Texts, and with no
141 Back-Cover Texts. A copy of the license is included in the
142 section entitled "GNU Free Documentation License".
147 Permission is granted to process this file through Tex and print the
148 results, provided the printed document carries copying permission
149 notice identical to this one except for the removal of this paragraph
150 (this paragraph not being relevant to the printed manual).
156 @title Using @value{AS}
157 @subtitle The @sc{gnu} Assembler
159 @subtitle for the @value{TARGET} family
162 @subtitle Version @value{VERSION}
165 The Free Software Foundation Inc. thanks The Nice Computer
166 Company of Australia for loaning Dean Elsner to write the
167 first (Vax) version of @command{as} for Project @sc{gnu}.
168 The proprietors, management and staff of TNCCA thank FSF for
169 distracting the boss while they got some work
172 @author Dean Elsner, Jay Fenlason & friends
176 \hfill {\it Using {\tt @value{AS}}}\par
177 \hfill Edited by Cygnus Support\par
179 %"boxit" macro for figures:
180 %Modified from Knuth's ``boxit'' macro from TeXbook (answer to exercise 21.3)
181 \gdef\boxit#1#2{\vbox{\hrule\hbox{\vrule\kern3pt
182 \vbox{\parindent=0pt\parskip=0pt\hsize=#1\kern3pt\strut\hfil
183 #2\hfil\strut\kern3pt}\kern3pt\vrule}\hrule}}%box with visible outline
184 \gdef\ibox#1#2{\hbox to #1{#2\hfil}\kern8pt}% invisible box
187 @vskip 0pt plus 1filll
188 Copyright @copyright{} 1991, 92, 93, 94, 95, 96, 97, 98, 99, 2000, 2001, 2002 Free Software Foundation, Inc.
190 Permission is granted to copy, distribute and/or modify this document
191 under the terms of the GNU Free Documentation License, Version 1.1
192 or any later version published by the Free Software Foundation;
193 with no Invariant Sections, with no Front-Cover Texts, and with no
194 Back-Cover Texts. A copy of the license is included in the
195 section entitled "GNU Free Documentation License".
201 @top Using @value{AS}
203 This file is a user guide to the @sc{gnu} assembler @command{@value{AS}} version
206 This version of the file describes @command{@value{AS}} configured to generate
207 code for @value{TARGET} architectures.
210 This document is distributed under the terms of the GNU Free
211 Documentation License. A copy of the license is included in the
212 section entitled "GNU Free Documentation License".
215 * Overview:: Overview
216 * Invoking:: Command-Line Options
218 * Sections:: Sections and Relocation
220 * Expressions:: Expressions
221 * Pseudo Ops:: Assembler Directives
222 * Machine Dependencies:: Machine Dependent Features
223 * Reporting Bugs:: Reporting Bugs
224 * Acknowledgements:: Who Did What
225 * GNU Free Documentation License:: GNU Free Documentation License
233 This manual is a user guide to the @sc{gnu} assembler @command{@value{AS}}.
235 This version of the manual describes @command{@value{AS}} configured to generate
236 code for @value{TARGET} architectures.
240 @cindex invocation summary
241 @cindex option summary
242 @cindex summary of options
243 Here is a brief summary of how to invoke @command{@value{AS}}. For details,
244 @pxref{Invoking,,Command-Line Options}.
246 @c man title AS the portable GNU assembler.
250 gcc(1), ld(1), and the Info entries for @file{binutils} and @file{ld}.
254 @c We don't use deffn and friends for the following because they seem
255 @c to be limited to one line for the header.
257 @c man begin SYNOPSIS
258 @value{AS} [@b{-a}[@b{cdhlns}][=@var{file}]] [@b{-D}] [@b{--defsym} @var{sym}=@var{val}]
259 [@b{-f}] [@b{--gstabs}] [@b{--gdwarf2}] [@b{--help}] [@b{-I} @var{dir}]
260 [@b{-J}] [@b{-K}] [@b{-L}]
261 [@b{--listing-lhs-width}=@var{NUM}] [@b{--listing-lhs-width2}=@var{NUM}]
262 [@b{--listing-rhs-width}=@var{NUM}] [@b{--listing-cont-lines}=@var{NUM}]
263 [@b{--keep-locals}] [@b{-o} @var{objfile}] [@b{-R}] [@b{--statistics}] [@b{-v}]
264 [@b{-version}] [@b{--version}] [@b{-W}] [@b{--warn}] [@b{--fatal-warnings}]
265 [@b{-w}] [@b{-x}] [@b{-Z}] [@b{--target-help}] [@var{target-options}]
266 [@b{--}|@var{files} @dots{}]
268 @c Target dependent options are listed below. Keep the list sorted.
269 @c Add an empty line for separation.
271 @c am29k has no machine-dependent assembler options
275 @emph{Target Alpha options:}
277 [@b{-mdebug} | @b{-no-mdebug}]
278 [@b{-relax}] [@b{-g}] [@b{-G@var{size}}]
279 [@b{-F}] [@b{-32addr}]
283 @emph{Target ARC options:}
289 @emph{Target ARM options:}
290 @c Don't document the deprecated options
291 [@b{-mcpu}=@var{processor}[+@var{extension}@dots{}]]
292 [@b{-march}=@var{architecture}[+@var{extension}@dots{}]]
293 [@b{-mfpu}=@var{floating-point-fromat}]
296 [@b{-mapcs-32}|@b{-mapcs-26}|@b{-mapcs-float}|
297 @b{-mapcs-reentrant}]
298 [@b{-mthumb-interwork}] [@b{-moabi}] [@b{-k}]
302 @emph{Target CRIS options:}
303 [@b{--underscore} | @b{--no-underscore}]
305 [@b{--emulation=criself} | @b{--emulation=crisaout}]
306 @c Deprecated -- deliberately not documented.
311 @emph{Target D10V options:}
316 @emph{Target D30V options:}
317 [@b{-O}|@b{-n}|@b{-N}]
320 @c Hitachi family chips have no machine-dependent assembler options
323 @c HPPA has no machine-dependent assembler options (yet).
327 @emph{Target i386 options:}
332 @emph{Target i960 options:}
333 @c see md_parse_option in tc-i960.c
334 [@b{-ACA}|@b{-ACA_A}|@b{-ACB}|@b{-ACC}|@b{-AKA}|@b{-AKB}|
336 [@b{-b}] [@b{-no-relax}]
340 @emph{Target IA-64 options:}
341 [@b{-mconstant-gp}|@b{-mauto-pic}]
342 [@b{-milp32}|@b{-milp64}|@b{-mlp64}|@b{-mp64}]
344 [@b{-x}|@b{-xexplicit}] [@b{-xauto}] [@b{-xdebug}]
348 @emph{Target IP2K options:}
349 [@b{-mip2022}|@b{-mip2022ext}]
353 @emph{Target M32R options:}
354 [@b{--m32rx}|@b{--[no-]warn-explicit-parallel-conflicts}|
359 @emph{Target M680X0 options:}
360 [@b{-l}] [@b{-m68000}|@b{-m68010}|@b{-m68020}|@dots{}]
364 @emph{Target M68HC11 options:}
365 [@b{-m68hc11}|@b{-m68hc12}]
366 [@b{--force-long-branchs}] [@b{--short-branchs}]
367 [@b{--strict-direct-mode}] [@b{--print-insn-syntax}]
368 [@b{--print-opcodes}] [@b{--generate-example}]
372 @emph{Target MCORE options:}
373 [@b{-jsri2bsr}] [@b{-sifilter}] [@b{-relax}]
374 [@b{-mcpu=[210|340]}]
378 @emph{Target MIPS options:}
379 [@b{-nocpp}] [@b{-EL}] [@b{-EB}] [@b{-n}] [@b{-O}[@var{optimization level}]]
380 [@b{-g}[@var{debug level}]] [@b{-G} @var{num}] [@b{-KPIC}] [@b{-call_shared}]
381 [@b{-non_shared}] [@b{-xgot}] [@b{--membedded-pic}]
382 [@b{-mabi}=@var{ABI}] [@b{-32}] [@b{-n32}] [@b{-64}] [@b{-mfp32}] [@b{-mgp32}]
383 [@b{-march}=@var{CPU}] [@b{-mtune}=@var{CPU}] [@b{-mips1}] [@b{-mips2}]
384 [@b{-mips3}] [@b{-mips4}] [@b{-mips5}] [@b{-mips32}] [@b{-mips64}]
385 [@b{-construct-floats}] [@b{-no-construct-floats}]
386 [@b{-trap}] [@b{-no-break}] [@b{-break}] [@b{-no-trap}]
387 [@b{-mfix7000}] [@b{-mno-fix7000}]
388 [@b{-mips16}] [@b{-no-mips16}]
389 [@b{-mips3d}] [@b{-no-mips3d}]
390 [@b{-mdmx}] [@b{-no-mdmx}]
391 [@b{-mdebug}] [@b{-no-mdebug}]
395 @emph{Target MMIX options:}
396 [@b{--fixed-special-register-names}] [@b{--globalize-symbols}]
397 [@b{--gnu-syntax}] [@b{--relax}] [@b{--no-predefined-symbols}]
398 [@b{--no-expand}] [@b{--no-merge-gregs}] [@b{-x}]
399 [@b{--linker-allocated-gregs}]
403 @emph{Target PDP11 options:}
404 [@b{-mpic}|@b{-mno-pic}] [@b{-mall}] [@b{-mno-extensions}]
405 [@b{-m}@var{extension}|@b{-mno-}@var{extension}]
406 [@b{-m}@var{cpu}] [@b{-m}@var{machine}]
410 @emph{Target picoJava options:}
415 @emph{Target PowerPC options:}
416 [@b{-mpwrx}|@b{-mpwr2}|@b{-mpwr}|@b{-m601}|@b{-mppc}|@b{-mppc32}|@b{-m603}|@b{-m604}|
417 @b{-m403}|@b{-m405}|@b{-mppc64}|@b{-m620}|@b{-mppc64bridge}|@b{-mbooke}|
418 @b{-mbooke32}|@b{-mbooke64}]
419 [@b{-mcom}|@b{-many}|@b{-maltivec}] [@b{-memb}]
420 [@b{-mregnames}|@b{-mno-regnames}]
421 [@b{-mrelocatable}|@b{-mrelocatable-lib}]
422 [@b{-mlittle}|@b{-mlittle-endian}|@b{-mbig}|@b{-mbig-endian}]
423 [@b{-msolaris}|@b{-mno-solaris}]
427 @emph{Target SPARC options:}
428 @c The order here is important. See c-sparc.texi.
429 [@b{-Av6}|@b{-Av7}|@b{-Av8}|@b{-Asparclet}|@b{-Asparclite}
430 @b{-Av8plus}|@b{-Av8plusa}|@b{-Av9}|@b{-Av9a}]
431 [@b{-xarch=v8plus}|@b{-xarch=v8plusa}] [@b{-bump}]
436 @emph{Target TIC54X options:}
437 [@b{-mcpu=54[123589]}|@b{-mcpu=54[56]lp}] [@b{-mfar-mode}|@b{-mf}]
438 [@b{-merrors-to-file} @var{<filename>}|@b{-me} @var{<filename>}]
441 @c Z8000 has no machine-dependent assembler options
450 Turn on listings, in any of a variety of ways:
454 omit false conditionals
457 omit debugging directives
460 include high-level source
466 include macro expansions
469 omit forms processing
475 set the name of the listing file
478 You may combine these options; for example, use @samp{-aln} for assembly
479 listing without forms processing. The @samp{=file} option, if used, must be
480 the last one. By itself, @samp{-a} defaults to @samp{-ahls}.
483 Ignored. This option is accepted for script compatibility with calls to
486 @item --defsym @var{sym}=@var{value}
487 Define the symbol @var{sym} to be @var{value} before assembling the input file.
488 @var{value} must be an integer constant. As in C, a leading @samp{0x}
489 indicates a hexadecimal value, and a leading @samp{0} indicates an octal value.
492 ``fast''---skip whitespace and comment preprocessing (assume source is
496 Generate stabs debugging information for each assembler line. This
497 may help debugging assembler code, if the debugger can handle it.
500 Generate DWARF2 debugging information for each assembler line. This
501 may help debugging assembler code, if the debugger can handle it. Note - this
502 option is only supported by some targets, not all of them.
505 Print a summary of the command line options and exit.
508 Print a summary of all target specific options and exit.
511 Add directory @var{dir} to the search list for @code{.include} directives.
514 Don't warn about signed overflow.
517 @ifclear DIFF-TBL-KLUGE
518 This option is accepted but has no effect on the @value{TARGET} family.
520 @ifset DIFF-TBL-KLUGE
521 Issue warnings when difference tables altered for long displacements.
526 Keep (in the symbol table) local symbols. On traditional a.out systems
527 these start with @samp{L}, but different systems have different local
530 @item --listing-lhs-width=@var{number}
531 Set the maximum width, in words, of the output data column for an assembler
532 listing to @var{number}.
534 @item --listing-lhs-width2=@var{number}
535 Set the maximum width, in words, of the output data column for continuation
536 lines in an assembler listing to @var{number}.
538 @item --listing-rhs-width=@var{number}
539 Set the maximum width of an input source line, as displayed in a listing, to
542 @item --listing-cont-lines=@var{number}
543 Set the maximum number of lines printed in a listing for a single line of input
546 @item -o @var{objfile}
547 Name the object-file output from @command{@value{AS}} @var{objfile}.
550 Fold the data section into the text section.
553 Print the maximum space (in bytes) and total time (in seconds) used by
556 @item --strip-local-absolute
557 Remove local absolute symbols from the outgoing symbol table.
561 Print the @command{as} version.
564 Print the @command{as} version and exit.
568 Suppress warning messages.
570 @item --fatal-warnings
571 Treat warnings as errors.
574 Don't suppress warning messages or treat them as errors.
583 Generate an object file even after errors.
585 @item -- | @var{files} @dots{}
586 Standard input, or source files to assemble.
591 The following options are available when @value{AS} is configured for
596 This option selects the core processor variant.
598 Select either big-endian (-EB) or little-endian (-EL) output.
603 The following options are available when @value{AS} is configured for the ARM
607 @item -mcpu=@var{processor}[+@var{extension}@dots{}]
608 Specify which ARM processor variant is the target.
609 @item -march=@var{architecture}[+@var{extension}@dots{}]
610 Specify which ARM architecture variant is used by the target.
611 @item -mfpu=@var{floating-point-format}
612 Select which Floating Point architecture is the target.
614 Enable Thumb only instruction decoding.
615 @item -mapcs-32 | -mapcs-26 | -mapcs-float | -mapcs-reentrant | -moabi
616 Select which procedure calling convention is in use.
618 Select either big-endian (-EB) or little-endian (-EL) output.
619 @item -mthumb-interwork
620 Specify that the code has been generated with interworking between Thumb and
623 Specify that PIC code has been generated.
628 See the info pages for documentation of the CRIS-specific options.
632 The following options are available when @value{AS} is configured for
635 @cindex D10V optimization
636 @cindex optimization, D10V
638 Optimize output by parallelizing instructions.
643 The following options are available when @value{AS} is configured for a D30V
646 @cindex D30V optimization
647 @cindex optimization, D30V
649 Optimize output by parallelizing instructions.
653 Warn when nops are generated.
655 @cindex D30V nops after 32-bit multiply
657 Warn when a nop after a 32-bit multiply instruction is generated.
662 The following options are available when @value{AS} is configured for the
663 Intel 80960 processor.
666 @item -ACA | -ACA_A | -ACB | -ACC | -AKA | -AKB | -AKC | -AMC
667 Specify which variant of the 960 architecture is the target.
670 Add code to collect statistics about branches taken.
673 Do not alter compare-and-branch instructions for long displacements;
680 The following options are available when @value{AS} is configured for the
686 Specifies that the extended IP2022 instructions are allowed.
689 Restores the default behaviour, which restricts the permitted instructions to
690 just the basic IP2022 ones.
696 The following options are available when @value{AS} is configured for the
697 Mitsubishi M32R series.
702 Specify which processor in the M32R family is the target. The default
703 is normally the M32R, but this option changes it to the M32RX.
705 @item --warn-explicit-parallel-conflicts or --Wp
706 Produce warning messages when questionable parallel constructs are
709 @item --no-warn-explicit-parallel-conflicts or --Wnp
710 Do not produce warning messages when questionable parallel constructs are
717 The following options are available when @value{AS} is configured for the
718 Motorola 68000 series.
723 Shorten references to undefined symbols, to one word instead of two.
725 @item -m68000 | -m68008 | -m68010 | -m68020 | -m68030
726 @itemx | -m68040 | -m68060 | -m68302 | -m68331 | -m68332
727 @itemx | -m68333 | -m68340 | -mcpu32 | -m5200
728 Specify what processor in the 68000 family is the target. The default
729 is normally the 68020, but this can be changed at configuration time.
731 @item -m68881 | -m68882 | -mno-68881 | -mno-68882
732 The target machine does (or does not) have a floating-point coprocessor.
733 The default is to assume a coprocessor for 68020, 68030, and cpu32. Although
734 the basic 68000 is not compatible with the 68881, a combination of the
735 two can be specified, since it's possible to do emulation of the
736 coprocessor instructions with the main processor.
738 @item -m68851 | -mno-68851
739 The target machine does (or does not) have a memory-management
740 unit coprocessor. The default is to assume an MMU for 68020 and up.
747 For details about the PDP-11 machine dependent features options,
748 see @ref{PDP-11-Options}.
751 @item -mpic | -mno-pic
752 Generate position-independent (or position-dependent) code. The
753 default is @option{-mpic}.
756 @itemx -mall-extensions
757 Enable all instruction set extensions. This is the default.
759 @item -mno-extensions
760 Disable all instruction set extensions.
762 @item -m@var{extension} | -mno-@var{extension}
763 Enable (or disable) a particular instruction set extension.
766 Enable the instruction set extensions supported by a particular CPU, and
767 disable all other extensions.
769 @item -m@var{machine}
770 Enable the instruction set extensions supported by a particular machine
771 model, and disable all other extensions.
777 The following options are available when @value{AS} is configured for
778 a picoJava processor.
782 @cindex PJ endianness
783 @cindex endianness, PJ
784 @cindex big endian output, PJ
786 Generate ``big endian'' format output.
788 @cindex little endian output, PJ
790 Generate ``little endian'' format output.
796 The following options are available when @value{AS} is configured for the
797 Motorola 68HC11 or 68HC12 series.
801 @item -m68hc11 | -m68hc12
802 Specify what processor is the target. The default is
803 defined by the configuration option when building the assembler.
805 @item --force-long-branchs
806 Relative branches are turned into absolute ones. This concerns
807 conditional branches, unconditional branches and branches to a
810 @item -S | --short-branchs
811 Do not turn relative branchs into absolute ones
812 when the offset is out of range.
814 @item --strict-direct-mode
815 Do not turn the direct addressing mode into extended addressing mode
816 when the instruction does not support direct addressing mode.
818 @item --print-insn-syntax
819 Print the syntax of instruction in case of error.
821 @item --print-opcodes
822 print the list of instructions with syntax and then exit.
824 @item --generate-example
825 print an example of instruction for each possible instruction and then exit.
826 This option is only useful for testing @command{@value{AS}}.
832 The following options are available when @command{@value{AS}} is configured
833 for the SPARC architecture:
836 @item -Av6 | -Av7 | -Av8 | -Asparclet | -Asparclite
837 @itemx -Av8plus | -Av8plusa | -Av9 | -Av9a
838 Explicitly select a variant of the SPARC architecture.
840 @samp{-Av8plus} and @samp{-Av8plusa} select a 32 bit environment.
841 @samp{-Av9} and @samp{-Av9a} select a 64 bit environment.
843 @samp{-Av8plusa} and @samp{-Av9a} enable the SPARC V9 instruction set with
844 UltraSPARC extensions.
846 @item -xarch=v8plus | -xarch=v8plusa
847 For compatibility with the Solaris v9 assembler. These options are
848 equivalent to -Av8plus and -Av8plusa, respectively.
851 Warn when the assembler switches to another architecture.
856 The following options are available when @value{AS} is configured for the 'c54x
861 Enable extended addressing mode. All addresses and relocations will assume
862 extended addressing (usually 23 bits).
863 @item -mcpu=@var{CPU_VERSION}
864 Sets the CPU version being compiled for.
865 @item -merrors-to-file @var{FILENAME}
866 Redirect error output to a file, for broken systems which don't support such
867 behaviour in the shell.
872 The following options are available when @value{AS} is configured for
873 a @sc{mips} processor.
877 This option sets the largest size of an object that can be referenced
878 implicitly with the @code{gp} register. It is only accepted for targets that
879 use ECOFF format, such as a DECstation running Ultrix. The default value is 8.
881 @cindex MIPS endianness
882 @cindex endianness, MIPS
883 @cindex big endian output, MIPS
885 Generate ``big endian'' format output.
887 @cindex little endian output, MIPS
889 Generate ``little endian'' format output.
899 Generate code for a particular @sc{mips} Instruction Set Architecture level.
900 @samp{-mips1} is an alias for @samp{-march=r3000}, @samp{-mips2} is an
901 alias for @samp{-march=r6000}, @samp{-mips3} is an alias for
902 @samp{-march=r4000} and @samp{-mips4} is an alias for @samp{-march=r8000}.
903 @samp{-mips5}, @samp{-mips32}, and @samp{-mips64} correspond to generic
904 @samp{MIPS V}, @samp{MIPS32}, and @samp{MIPS64} ISA processors,
907 @item -march=@var{CPU}
908 Generate code for a particular @sc{mips} cpu.
910 @item -mtune=@var{cpu}
911 Schedule and tune for a particular @sc{mips} cpu.
915 Cause nops to be inserted if the read of the destination register
916 of an mfhi or mflo instruction occurs in the following two instructions.
920 Cause stabs-style debugging output to go into an ECOFF-style .mdebug
921 section instead of the standard ELF .stabs sections.
925 The register sizes are normally inferred from the ISA and ABI, but these
926 flags force a certain group of registers to be treated as 32 bits wide at
927 all times. @samp{-mgp32} controls the size of general-purpose registers
928 and @samp{-mfp32} controls the size of floating-point registers.
932 Generate code for the MIPS 16 processor. This is equivalent to putting
933 @code{.set mips16} at the start of the assembly file. @samp{-no-mips16}
934 turns off this option.
938 Generate code for the MIPS-3D Application Specific Extension.
939 This tells the assembler to accept MIPS-3D instructions.
940 @samp{-no-mips3d} turns off this option.
944 Generate code for the MDMX Application Specific Extension.
945 This tells the assembler to accept MDMX instructions.
946 @samp{-no-mdmx} turns off this option.
948 @item --construct-floats
949 @itemx --no-construct-floats
950 The @samp{--no-construct-floats} option disables the construction of
951 double width floating point constants by loading the two halves of the
952 value into the two single width floating point registers that make up
953 the double width register. By default @samp{--construct-floats} is
954 selected, allowing construction of these floating point constants.
957 @item --emulation=@var{name}
958 This option causes @command{@value{AS}} to emulate @command{@value{AS}} configured
959 for some other target, in all respects, including output format (choosing
960 between ELF and ECOFF only), handling of pseudo-opcodes which may generate
961 debugging information or store symbol table information, and default
962 endianness. The available configuration names are: @samp{mipsecoff},
963 @samp{mipself}, @samp{mipslecoff}, @samp{mipsbecoff}, @samp{mipslelf},
964 @samp{mipsbelf}. The first two do not alter the default endianness from that
965 of the primary target for which the assembler was configured; the others change
966 the default to little- or big-endian as indicated by the @samp{b} or @samp{l}
967 in the name. Using @samp{-EB} or @samp{-EL} will override the endianness
968 selection in any case.
970 This option is currently supported only when the primary target
971 @command{@value{AS}} is configured for is a @sc{mips} ELF or ECOFF target.
972 Furthermore, the primary target or others specified with
973 @samp{--enable-targets=@dots{}} at configuration time must include support for
974 the other format, if both are to be available. For example, the Irix 5
975 configuration includes support for both.
977 Eventually, this option will support more configurations, with more
978 fine-grained control over the assembler's behavior, and will be supported for
982 @command{@value{AS}} ignores this option. It is accepted for compatibility with
989 Control how to deal with multiplication overflow and division by zero.
990 @samp{--trap} or @samp{--no-break} (which are synonyms) take a trap exception
991 (and only work for Instruction Set Architecture level 2 and higher);
992 @samp{--break} or @samp{--no-trap} (also synonyms, and the default) take a
996 When this option is used, @command{@value{AS}} will issue a warning every
997 time it generates a nop instruction from a macro.
1002 The following options are available when @value{AS} is configured for
1008 Enable or disable the JSRI to BSR transformation. By default this is enabled.
1009 The command line option @samp{-nojsri2bsr} can be used to disable it.
1013 Enable or disable the silicon filter behaviour. By default this is disabled.
1014 The default can be overridden by the @samp{-sifilter} command line option.
1017 Alter jump instructions for long displacements.
1019 @item -mcpu=[210|340]
1020 Select the cpu type on the target hardware. This controls which instructions
1024 Assemble for a big endian target.
1027 Assemble for a little endian target.
1033 See the info pages for documentation of the MMIX-specific options.
1039 * Manual:: Structure of this Manual
1040 * GNU Assembler:: The GNU Assembler
1041 * Object Formats:: Object File Formats
1042 * Command Line:: Command Line
1043 * Input Files:: Input Files
1044 * Object:: Output (Object) File
1045 * Errors:: Error and Warning Messages
1049 @section Structure of this Manual
1051 @cindex manual, structure and purpose
1052 This manual is intended to describe what you need to know to use
1053 @sc{gnu} @command{@value{AS}}. We cover the syntax expected in source files, including
1054 notation for symbols, constants, and expressions; the directives that
1055 @command{@value{AS}} understands; and of course how to invoke @command{@value{AS}}.
1058 We also cover special features in the @value{TARGET}
1059 configuration of @command{@value{AS}}, including assembler directives.
1062 This manual also describes some of the machine-dependent features of
1063 various flavors of the assembler.
1066 @cindex machine instructions (not covered)
1067 On the other hand, this manual is @emph{not} intended as an introduction
1068 to programming in assembly language---let alone programming in general!
1069 In a similar vein, we make no attempt to introduce the machine
1070 architecture; we do @emph{not} describe the instruction set, standard
1071 mnemonics, registers or addressing modes that are standard to a
1072 particular architecture.
1074 You may want to consult the manufacturer's
1075 machine architecture manual for this information.
1079 For information on the H8/300 machine instruction set, see @cite{H8/300
1080 Series Programming Manual} (Hitachi ADE--602--025). For the H8/300H,
1081 see @cite{H8/300H Series Programming Manual} (Hitachi).
1084 For information on the H8/500 machine instruction set, see @cite{H8/500
1085 Series Programming Manual} (Hitachi M21T001).
1088 For information on the Hitachi SH machine instruction set, see
1089 @cite{SH-Microcomputer User's Manual} (Hitachi Micro Systems, Inc.).
1092 For information on the Z8000 machine instruction set, see @cite{Z8000 CPU Technical Manual}
1096 @c I think this is premature---doc@cygnus.com, 17jan1991
1098 Throughout this manual, we assume that you are running @dfn{GNU},
1099 the portable operating system from the @dfn{Free Software
1100 Foundation, Inc.}. This restricts our attention to certain kinds of
1101 computer (in particular, the kinds of computers that @sc{gnu} can run on);
1102 once this assumption is granted examples and definitions need less
1105 @command{@value{AS}} is part of a team of programs that turn a high-level
1106 human-readable series of instructions into a low-level
1107 computer-readable series of instructions. Different versions of
1108 @command{@value{AS}} are used for different kinds of computer.
1111 @c There used to be a section "Terminology" here, which defined
1112 @c "contents", "byte", "word", and "long". Defining "word" to any
1113 @c particular size is confusing when the .word directive may generate 16
1114 @c bits on one machine and 32 bits on another; in general, for the user
1115 @c version of this manual, none of these terms seem essential to define.
1116 @c They were used very little even in the former draft of the manual;
1117 @c this draft makes an effort to avoid them (except in names of
1121 @section The GNU Assembler
1123 @c man begin DESCRIPTION
1125 @sc{gnu} @command{as} is really a family of assemblers.
1127 This manual describes @command{@value{AS}}, a member of that family which is
1128 configured for the @value{TARGET} architectures.
1130 If you use (or have used) the @sc{gnu} assembler on one architecture, you
1131 should find a fairly similar environment when you use it on another
1132 architecture. Each version has much in common with the others,
1133 including object file formats, most assembler directives (often called
1134 @dfn{pseudo-ops}) and assembler syntax.@refill
1136 @cindex purpose of @sc{gnu} assembler
1137 @command{@value{AS}} is primarily intended to assemble the output of the
1138 @sc{gnu} C compiler @code{@value{GCC}} for use by the linker
1139 @code{@value{LD}}. Nevertheless, we've tried to make @command{@value{AS}}
1140 assemble correctly everything that other assemblers for the same
1141 machine would assemble.
1143 Any exceptions are documented explicitly (@pxref{Machine Dependencies}).
1146 @c This remark should appear in generic version of manual; assumption
1147 @c here is that generic version sets M680x0.
1148 This doesn't mean @command{@value{AS}} always uses the same syntax as another
1149 assembler for the same architecture; for example, we know of several
1150 incompatible versions of 680x0 assembly language syntax.
1155 Unlike older assemblers, @command{@value{AS}} is designed to assemble a source
1156 program in one pass of the source file. This has a subtle impact on the
1157 @kbd{.org} directive (@pxref{Org,,@code{.org}}).
1159 @node Object Formats
1160 @section Object File Formats
1162 @cindex object file format
1163 The @sc{gnu} assembler can be configured to produce several alternative
1164 object file formats. For the most part, this does not affect how you
1165 write assembly language programs; but directives for debugging symbols
1166 are typically different in different file formats. @xref{Symbol
1167 Attributes,,Symbol Attributes}.
1170 On the @value{TARGET}, @command{@value{AS}} is configured to produce
1171 @value{OBJ-NAME} format object files.
1173 @c The following should exhaust all configs that set MULTI-OBJ, ideally
1175 On the @value{TARGET}, @command{@value{AS}} can be configured to produce either
1176 @code{a.out} or COFF format object files.
1179 On the @value{TARGET}, @command{@value{AS}} can be configured to produce either
1180 @code{b.out} or COFF format object files.
1183 On the @value{TARGET}, @command{@value{AS}} can be configured to produce either
1184 SOM or ELF format object files.
1189 @section Command Line
1191 @cindex command line conventions
1193 After the program name @command{@value{AS}}, the command line may contain
1194 options and file names. Options may appear in any order, and may be
1195 before, after, or between file names. The order of file names is
1198 @cindex standard input, as input file
1200 @file{--} (two hyphens) by itself names the standard input file
1201 explicitly, as one of the files for @command{@value{AS}} to assemble.
1203 @cindex options, command line
1204 Except for @samp{--} any command line argument that begins with a
1205 hyphen (@samp{-}) is an option. Each option changes the behavior of
1206 @command{@value{AS}}. No option changes the way another option works. An
1207 option is a @samp{-} followed by one or more letters; the case of
1208 the letter is important. All options are optional.
1210 Some options expect exactly one file name to follow them. The file
1211 name may either immediately follow the option's letter (compatible
1212 with older assemblers) or it may be the next command argument (@sc{gnu}
1213 standard). These two command lines are equivalent:
1216 @value{AS} -o my-object-file.o mumble.s
1217 @value{AS} -omy-object-file.o mumble.s
1221 @section Input Files
1224 @cindex source program
1225 @cindex files, input
1226 We use the phrase @dfn{source program}, abbreviated @dfn{source}, to
1227 describe the program input to one run of @command{@value{AS}}. The program may
1228 be in one or more files; how the source is partitioned into files
1229 doesn't change the meaning of the source.
1231 @c I added "con" prefix to "catenation" just to prove I can overcome my
1232 @c APL training... doc@cygnus.com
1233 The source program is a concatenation of the text in all the files, in the
1236 @c man begin DESCRIPTION
1237 Each time you run @command{@value{AS}} it assembles exactly one source
1238 program. The source program is made up of one or more files.
1239 (The standard input is also a file.)
1241 You give @command{@value{AS}} a command line that has zero or more input file
1242 names. The input files are read (from left file name to right). A
1243 command line argument (in any position) that has no special meaning
1244 is taken to be an input file name.
1246 If you give @command{@value{AS}} no file names it attempts to read one input file
1247 from the @command{@value{AS}} standard input, which is normally your terminal. You
1248 may have to type @key{ctl-D} to tell @command{@value{AS}} there is no more program
1251 Use @samp{--} if you need to explicitly name the standard input file
1252 in your command line.
1254 If the source is empty, @command{@value{AS}} produces a small, empty object
1259 @subheading Filenames and Line-numbers
1261 @cindex input file linenumbers
1262 @cindex line numbers, in input files
1263 There are two ways of locating a line in the input file (or files) and
1264 either may be used in reporting error messages. One way refers to a line
1265 number in a physical file; the other refers to a line number in a
1266 ``logical'' file. @xref{Errors, ,Error and Warning Messages}.
1268 @dfn{Physical files} are those files named in the command line given
1269 to @command{@value{AS}}.
1271 @dfn{Logical files} are simply names declared explicitly by assembler
1272 directives; they bear no relation to physical files. Logical file names help
1273 error messages reflect the original source file, when @command{@value{AS}} source
1274 is itself synthesized from other files. @command{@value{AS}} understands the
1275 @samp{#} directives emitted by the @code{@value{GCC}} preprocessor. See also
1276 @ref{File,,@code{.file}}.
1279 @section Output (Object) File
1285 Every time you run @command{@value{AS}} it produces an output file, which is
1286 your assembly language program translated into numbers. This file
1287 is the object file. Its default name is
1295 @code{b.out} when @command{@value{AS}} is configured for the Intel 80960.
1297 You can give it another name by using the @option{-o} option. Conventionally,
1298 object file names end with @file{.o}. The default name is used for historical
1299 reasons: older assemblers were capable of assembling self-contained programs
1300 directly into a runnable program. (For some formats, this isn't currently
1301 possible, but it can be done for the @code{a.out} format.)
1305 The object file is meant for input to the linker @code{@value{LD}}. It contains
1306 assembled program code, information to help @code{@value{LD}} integrate
1307 the assembled program into a runnable file, and (optionally) symbolic
1308 information for the debugger.
1310 @c link above to some info file(s) like the description of a.out.
1311 @c don't forget to describe @sc{gnu} info as well as Unix lossage.
1314 @section Error and Warning Messages
1316 @c man begin DESCRIPTION
1318 @cindex error messages
1319 @cindex warning messages
1320 @cindex messages from assembler
1321 @command{@value{AS}} may write warnings and error messages to the standard error
1322 file (usually your terminal). This should not happen when a compiler
1323 runs @command{@value{AS}} automatically. Warnings report an assumption made so
1324 that @command{@value{AS}} could keep assembling a flawed program; errors report a
1325 grave problem that stops the assembly.
1329 @cindex format of warning messages
1330 Warning messages have the format
1333 file_name:@b{NNN}:Warning Message Text
1337 @cindex line numbers, in warnings/errors
1338 (where @b{NNN} is a line number). If a logical file name has been given
1339 (@pxref{File,,@code{.file}}) it is used for the filename, otherwise the name of
1340 the current input file is used. If a logical line number was given
1342 (@pxref{Line,,@code{.line}})
1346 (@pxref{Line,,@code{.line}})
1349 (@pxref{Ln,,@code{.ln}})
1352 then it is used to calculate the number printed,
1353 otherwise the actual line in the current source file is printed. The
1354 message text is intended to be self explanatory (in the grand Unix
1357 @cindex format of error messages
1358 Error messages have the format
1360 file_name:@b{NNN}:FATAL:Error Message Text
1362 The file name and line number are derived as for warning
1363 messages. The actual message text may be rather less explanatory
1364 because many of them aren't supposed to happen.
1367 @chapter Command-Line Options
1369 @cindex options, all versions of assembler
1370 This chapter describes command-line options available in @emph{all}
1371 versions of the @sc{gnu} assembler; @pxref{Machine Dependencies}, for options specific
1373 to the @value{TARGET}.
1376 to particular machine architectures.
1379 @c man begin DESCRIPTION
1381 If you are invoking @command{@value{AS}} via the @sc{gnu} C compiler (version 2),
1382 you can use the @samp{-Wa} option to pass arguments through to the assembler.
1383 The assembler arguments must be separated from each other (and the @samp{-Wa})
1384 by commas. For example:
1387 gcc -c -g -O -Wa,-alh,-L file.c
1391 This passes two options to the assembler: @samp{-alh} (emit a listing to
1392 standard output with with high-level and assembly source) and @samp{-L} (retain
1393 local symbols in the symbol table).
1395 Usually you do not need to use this @samp{-Wa} mechanism, since many compiler
1396 command-line options are automatically passed to the assembler by the compiler.
1397 (You can call the @sc{gnu} compiler driver with the @samp{-v} option to see
1398 precisely what options it passes to each compilation pass, including the
1404 * a:: -a[cdhlns] enable listings
1405 * D:: -D for compatibility
1406 * f:: -f to work faster
1407 * I:: -I for .include search path
1408 @ifclear DIFF-TBL-KLUGE
1409 * K:: -K for compatibility
1411 @ifset DIFF-TBL-KLUGE
1412 * K:: -K for difference tables
1415 * L:: -L to retain local labels
1416 * listing:: --listing-XXX to configure listing output
1417 * M:: -M or --mri to assemble in MRI compatibility mode
1418 * MD:: --MD for dependency tracking
1419 * o:: -o to name the object file
1420 * R:: -R to join data and text sections
1421 * statistics:: --statistics to see statistics about assembly
1422 * traditional-format:: --traditional-format for compatible output
1423 * v:: -v to announce version
1424 * W:: -W, --no-warn, --warn, --fatal-warnings to control warnings
1425 * Z:: -Z to make object file even after errors
1429 @section Enable Listings: @option{-a[cdhlns]}
1438 @cindex listings, enabling
1439 @cindex assembly listings, enabling
1441 These options enable listing output from the assembler. By itself,
1442 @samp{-a} requests high-level, assembly, and symbols listing.
1443 You can use other letters to select specific options for the list:
1444 @samp{-ah} requests a high-level language listing,
1445 @samp{-al} requests an output-program assembly listing, and
1446 @samp{-as} requests a symbol table listing.
1447 High-level listings require that a compiler debugging option like
1448 @samp{-g} be used, and that assembly listings (@samp{-al}) be requested
1451 Use the @samp{-ac} option to omit false conditionals from a listing. Any lines
1452 which are not assembled because of a false @code{.if} (or @code{.ifdef}, or any
1453 other conditional), or a true @code{.if} followed by an @code{.else}, will be
1454 omitted from the listing.
1456 Use the @samp{-ad} option to omit debugging directives from the
1459 Once you have specified one of these options, you can further control
1460 listing output and its appearance using the directives @code{.list},
1461 @code{.nolist}, @code{.psize}, @code{.eject}, @code{.title}, and
1463 The @samp{-an} option turns off all forms processing.
1464 If you do not request listing output with one of the @samp{-a} options, the
1465 listing-control directives have no effect.
1467 The letters after @samp{-a} may be combined into one option,
1468 @emph{e.g.}, @samp{-aln}.
1470 Note if the assembler source is coming from the standard input (eg because it
1471 is being created by @code{@value{GCC}} and the @samp{-pipe} command line switch
1472 is being used) then the listing will not contain any comments or preprocessor
1473 directives. This is because the listing code buffers input source lines from
1474 stdin only after they have been preprocessed by the assembler. This reduces
1475 memory usage and makes the code more efficient.
1478 @section @option{-D}
1481 This option has no effect whatsoever, but it is accepted to make it more
1482 likely that scripts written for other assemblers also work with
1483 @command{@value{AS}}.
1486 @section Work Faster: @option{-f}
1489 @cindex trusted compiler
1490 @cindex faster processing (@option{-f})
1491 @samp{-f} should only be used when assembling programs written by a
1492 (trusted) compiler. @samp{-f} stops the assembler from doing whitespace
1493 and comment preprocessing on
1494 the input file(s) before assembling them. @xref{Preprocessing,
1498 @emph{Warning:} if you use @samp{-f} when the files actually need to be
1499 preprocessed (if they contain comments, for example), @command{@value{AS}} does
1504 @section @code{.include} search path: @option{-I} @var{path}
1506 @kindex -I @var{path}
1507 @cindex paths for @code{.include}
1508 @cindex search path for @code{.include}
1509 @cindex @code{include} directive search path
1510 Use this option to add a @var{path} to the list of directories
1511 @command{@value{AS}} searches for files specified in @code{.include}
1512 directives (@pxref{Include,,@code{.include}}). You may use @option{-I} as
1513 many times as necessary to include a variety of paths. The current
1514 working directory is always searched first; after that, @command{@value{AS}}
1515 searches any @samp{-I} directories in the same order as they were
1516 specified (left to right) on the command line.
1519 @section Difference Tables: @option{-K}
1522 @ifclear DIFF-TBL-KLUGE
1523 On the @value{TARGET} family, this option is allowed, but has no effect. It is
1524 permitted for compatibility with the @sc{gnu} assembler on other platforms,
1525 where it can be used to warn when the assembler alters the machine code
1526 generated for @samp{.word} directives in difference tables. The @value{TARGET}
1527 family does not have the addressing limitations that sometimes lead to this
1528 alteration on other platforms.
1531 @ifset DIFF-TBL-KLUGE
1532 @cindex difference tables, warning
1533 @cindex warning for altered difference tables
1534 @command{@value{AS}} sometimes alters the code emitted for directives of the form
1535 @samp{.word @var{sym1}-@var{sym2}}; @pxref{Word,,@code{.word}}.
1536 You can use the @samp{-K} option if you want a warning issued when this
1541 @section Include Local Labels: @option{-L}
1544 @cindex local labels, retaining in output
1545 Labels beginning with @samp{L} (upper case only) are called @dfn{local
1546 labels}. @xref{Symbol Names}. Normally you do not see such labels when
1547 debugging, because they are intended for the use of programs (like
1548 compilers) that compose assembler programs, not for your notice.
1549 Normally both @command{@value{AS}} and @code{@value{LD}} discard such labels, so you do not
1550 normally debug with them.
1552 This option tells @command{@value{AS}} to retain those @samp{L@dots{}} symbols
1553 in the object file. Usually if you do this you also tell the linker
1554 @code{@value{LD}} to preserve symbols whose names begin with @samp{L}.
1556 By default, a local label is any label beginning with @samp{L}, but each
1557 target is allowed to redefine the local label prefix.
1559 On the HPPA local labels begin with @samp{L$}.
1563 @section Configuring listing output: @option{--listing}
1565 The listing feature of the assembler can be enabled via the command line switch
1566 @samp{-a} (@pxref{a}). This feature combines the input source file(s) with a
1567 hex dump of the corresponding locations in the output object file, and displays
1568 them as a listing file. The format of this listing can be controlled by pseudo
1569 ops inside the assembler source (@pxref{List} @pxref{Title} @pxref{Sbttl}
1570 @pxref{Psize} @pxref{Eject}) and also by the following switches:
1573 @item --listing-lhs-width=@samp{number}
1574 @kindex --listing-lhs-width
1575 @cindex Width of first line disassembly output
1576 Sets the maximum width, in words, of the first line of the hex byte dump. This
1577 dump appears on the left hand side of the listing output.
1579 @item --listing-lhs-width2=@samp{number}
1580 @kindex --listing-lhs-width2
1581 @cindex Width of continuation lines of disassembly output
1582 Sets the maximum width, in words, of any further lines of the hex byte dump for
1583 a given input source line. If this value is not specified, it defaults to being
1584 the same as the value specified for @samp{--listing-lhs-width}. If neither
1585 switch is used the default is to one.
1587 @item --listing-rhs-width=@samp{number}
1588 @kindex --listing-rhs-width
1589 @cindex Width of source line output
1590 Sets the maximum width, in characters, of the source line that is displayed
1591 alongside the hex dump. The default value for this parameter is 100. The
1592 source line is displayed on the right hand side of the listing output.
1594 @item --listing-cont-lines=@samp{number}
1595 @kindex --listing-cont-lines
1596 @cindex Maximum number of continuation lines
1597 Sets the maximum number of continuation lines of hex dump that will be
1598 displayed for a given single line of source input. The default value is 4.
1602 @section Assemble in MRI Compatibility Mode: @option{-M}
1605 @cindex MRI compatibility mode
1606 The @option{-M} or @option{--mri} option selects MRI compatibility mode. This
1607 changes the syntax and pseudo-op handling of @command{@value{AS}} to make it
1608 compatible with the @code{ASM68K} or the @code{ASM960} (depending upon the
1609 configured target) assembler from Microtec Research. The exact nature of the
1610 MRI syntax will not be documented here; see the MRI manuals for more
1611 information. Note in particular that the handling of macros and macro
1612 arguments is somewhat different. The purpose of this option is to permit
1613 assembling existing MRI assembler code using @command{@value{AS}}.
1615 The MRI compatibility is not complete. Certain operations of the MRI assembler
1616 depend upon its object file format, and can not be supported using other object
1617 file formats. Supporting these would require enhancing each object file format
1618 individually. These are:
1621 @item global symbols in common section
1623 The m68k MRI assembler supports common sections which are merged by the linker.
1624 Other object file formats do not support this. @command{@value{AS}} handles
1625 common sections by treating them as a single common symbol. It permits local
1626 symbols to be defined within a common section, but it can not support global
1627 symbols, since it has no way to describe them.
1629 @item complex relocations
1631 The MRI assemblers support relocations against a negated section address, and
1632 relocations which combine the start addresses of two or more sections. These
1633 are not support by other object file formats.
1635 @item @code{END} pseudo-op specifying start address
1637 The MRI @code{END} pseudo-op permits the specification of a start address.
1638 This is not supported by other object file formats. The start address may
1639 instead be specified using the @option{-e} option to the linker, or in a linker
1642 @item @code{IDNT}, @code{.ident} and @code{NAME} pseudo-ops
1644 The MRI @code{IDNT}, @code{.ident} and @code{NAME} pseudo-ops assign a module
1645 name to the output file. This is not supported by other object file formats.
1647 @item @code{ORG} pseudo-op
1649 The m68k MRI @code{ORG} pseudo-op begins an absolute section at a given
1650 address. This differs from the usual @command{@value{AS}} @code{.org} pseudo-op,
1651 which changes the location within the current section. Absolute sections are
1652 not supported by other object file formats. The address of a section may be
1653 assigned within a linker script.
1656 There are some other features of the MRI assembler which are not supported by
1657 @command{@value{AS}}, typically either because they are difficult or because they
1658 seem of little consequence. Some of these may be supported in future releases.
1662 @item EBCDIC strings
1664 EBCDIC strings are not supported.
1666 @item packed binary coded decimal
1668 Packed binary coded decimal is not supported. This means that the @code{DC.P}
1669 and @code{DCB.P} pseudo-ops are not supported.
1671 @item @code{FEQU} pseudo-op
1673 The m68k @code{FEQU} pseudo-op is not supported.
1675 @item @code{NOOBJ} pseudo-op
1677 The m68k @code{NOOBJ} pseudo-op is not supported.
1679 @item @code{OPT} branch control options
1681 The m68k @code{OPT} branch control options---@code{B}, @code{BRS}, @code{BRB},
1682 @code{BRL}, and @code{BRW}---are ignored. @command{@value{AS}} automatically
1683 relaxes all branches, whether forward or backward, to an appropriate size, so
1684 these options serve no purpose.
1686 @item @code{OPT} list control options
1688 The following m68k @code{OPT} list control options are ignored: @code{C},
1689 @code{CEX}, @code{CL}, @code{CRE}, @code{E}, @code{G}, @code{I}, @code{M},
1690 @code{MEX}, @code{MC}, @code{MD}, @code{X}.
1692 @item other @code{OPT} options
1694 The following m68k @code{OPT} options are ignored: @code{NEST}, @code{O},
1695 @code{OLD}, @code{OP}, @code{P}, @code{PCO}, @code{PCR}, @code{PCS}, @code{R}.
1697 @item @code{OPT} @code{D} option is default
1699 The m68k @code{OPT} @code{D} option is the default, unlike the MRI assembler.
1700 @code{OPT NOD} may be used to turn it off.
1702 @item @code{XREF} pseudo-op.
1704 The m68k @code{XREF} pseudo-op is ignored.
1706 @item @code{.debug} pseudo-op
1708 The i960 @code{.debug} pseudo-op is not supported.
1710 @item @code{.extended} pseudo-op
1712 The i960 @code{.extended} pseudo-op is not supported.
1714 @item @code{.list} pseudo-op.
1716 The various options of the i960 @code{.list} pseudo-op are not supported.
1718 @item @code{.optimize} pseudo-op
1720 The i960 @code{.optimize} pseudo-op is not supported.
1722 @item @code{.output} pseudo-op
1724 The i960 @code{.output} pseudo-op is not supported.
1726 @item @code{.setreal} pseudo-op
1728 The i960 @code{.setreal} pseudo-op is not supported.
1733 @section Dependency tracking: @option{--MD}
1736 @cindex dependency tracking
1739 @command{@value{AS}} can generate a dependency file for the file it creates. This
1740 file consists of a single rule suitable for @code{make} describing the
1741 dependencies of the main source file.
1743 The rule is written to the file named in its argument.
1745 This feature is used in the automatic updating of makefiles.
1748 @section Name the Object File: @option{-o}
1751 @cindex naming object file
1752 @cindex object file name
1753 There is always one object file output when you run @command{@value{AS}}. By
1754 default it has the name
1757 @file{a.out} (or @file{b.out}, for Intel 960 targets only).
1771 You use this option (which takes exactly one filename) to give the
1772 object file a different name.
1774 Whatever the object file is called, @command{@value{AS}} overwrites any
1775 existing file of the same name.
1778 @section Join Data and Text Sections: @option{-R}
1781 @cindex data and text sections, joining
1782 @cindex text and data sections, joining
1783 @cindex joining text and data sections
1784 @cindex merging text and data sections
1785 @option{-R} tells @command{@value{AS}} to write the object file as if all
1786 data-section data lives in the text section. This is only done at
1787 the very last moment: your binary data are the same, but data
1788 section parts are relocated differently. The data section part of
1789 your object file is zero bytes long because all its bytes are
1790 appended to the text section. (@xref{Sections,,Sections and Relocation}.)
1792 When you specify @option{-R} it would be possible to generate shorter
1793 address displacements (because we do not have to cross between text and
1794 data section). We refrain from doing this simply for compatibility with
1795 older versions of @command{@value{AS}}. In future, @option{-R} may work this way.
1798 When @command{@value{AS}} is configured for COFF output,
1799 this option is only useful if you use sections named @samp{.text} and
1804 @option{-R} is not supported for any of the HPPA targets. Using
1805 @option{-R} generates a warning from @command{@value{AS}}.
1809 @section Display Assembly Statistics: @option{--statistics}
1811 @kindex --statistics
1812 @cindex statistics, about assembly
1813 @cindex time, total for assembly
1814 @cindex space used, maximum for assembly
1815 Use @samp{--statistics} to display two statistics about the resources used by
1816 @command{@value{AS}}: the maximum amount of space allocated during the assembly
1817 (in bytes), and the total execution time taken for the assembly (in @sc{cpu}
1820 @node traditional-format
1821 @section Compatible output: @option{--traditional-format}
1823 @kindex --traditional-format
1824 For some targets, the output of @command{@value{AS}} is different in some ways
1825 from the output of some existing assembler. This switch requests
1826 @command{@value{AS}} to use the traditional format instead.
1828 For example, it disables the exception frame optimizations which
1829 @command{@value{AS}} normally does by default on @code{@value{GCC}} output.
1832 @section Announce Version: @option{-v}
1836 @cindex assembler version
1837 @cindex version of assembler
1838 You can find out what version of as is running by including the
1839 option @samp{-v} (which you can also spell as @samp{-version}) on the
1843 @section Control Warnings: @option{-W}, @option{--warn}, @option{--no-warn}, @option{--fatal-warnings}
1845 @command{@value{AS}} should never give a warning or error message when
1846 assembling compiler output. But programs written by people often
1847 cause @command{@value{AS}} to give a warning that a particular assumption was
1848 made. All such warnings are directed to the standard error file.
1851 @kindex @samp{--no-warn}
1852 @cindex suppressing warnings
1853 @cindex warnings, suppressing
1854 If you use the @option{-W} and @option{--no-warn} options, no warnings are issued.
1855 This only affects the warning messages: it does not change any particular of
1856 how @command{@value{AS}} assembles your file. Errors, which stop the assembly,
1859 @kindex @samp{--fatal-warnings}
1860 @cindex errors, caused by warnings
1861 @cindex warnings, causing error
1862 If you use the @option{--fatal-warnings} option, @command{@value{AS}} considers
1863 files that generate warnings to be in error.
1865 @kindex @samp{--warn}
1866 @cindex warnings, switching on
1867 You can switch these options off again by specifying @option{--warn}, which
1868 causes warnings to be output as usual.
1871 @section Generate Object File in Spite of Errors: @option{-Z}
1872 @cindex object file, after errors
1873 @cindex errors, continuing after
1874 After an error message, @command{@value{AS}} normally produces no output. If for
1875 some reason you are interested in object file output even after
1876 @command{@value{AS}} gives an error message on your program, use the @samp{-Z}
1877 option. If there are any errors, @command{@value{AS}} continues anyways, and
1878 writes an object file after a final warning message of the form @samp{@var{n}
1879 errors, @var{m} warnings, generating bad object file.}
1884 @cindex machine-independent syntax
1885 @cindex syntax, machine-independent
1886 This chapter describes the machine-independent syntax allowed in a
1887 source file. @command{@value{AS}} syntax is similar to what many other
1888 assemblers use; it is inspired by the BSD 4.2
1893 assembler, except that @command{@value{AS}} does not assemble Vax bit-fields.
1897 * Preprocessing:: Preprocessing
1898 * Whitespace:: Whitespace
1899 * Comments:: Comments
1900 * Symbol Intro:: Symbols
1901 * Statements:: Statements
1902 * Constants:: Constants
1906 @section Preprocessing
1908 @cindex preprocessing
1909 The @command{@value{AS}} internal preprocessor:
1911 @cindex whitespace, removed by preprocessor
1913 adjusts and removes extra whitespace. It leaves one space or tab before
1914 the keywords on a line, and turns any other whitespace on the line into
1917 @cindex comments, removed by preprocessor
1919 removes all comments, replacing them with a single space, or an
1920 appropriate number of newlines.
1922 @cindex constants, converted by preprocessor
1924 converts character constants into the appropriate numeric values.
1927 It does not do macro processing, include file handling, or
1928 anything else you may get from your C compiler's preprocessor. You can
1929 do include file processing with the @code{.include} directive
1930 (@pxref{Include,,@code{.include}}). You can use the @sc{gnu} C compiler driver
1931 to get other ``CPP'' style preprocessing, by giving the input file a
1932 @samp{.S} suffix. @xref{Overall Options,, Options Controlling the Kind of
1933 Output, gcc.info, Using GNU CC}.
1935 Excess whitespace, comments, and character constants
1936 cannot be used in the portions of the input text that are not
1939 @cindex turning preprocessing on and off
1940 @cindex preprocessing, turning on and off
1943 If the first line of an input file is @code{#NO_APP} or if you use the
1944 @samp{-f} option, whitespace and comments are not removed from the input file.
1945 Within an input file, you can ask for whitespace and comment removal in
1946 specific portions of the by putting a line that says @code{#APP} before the
1947 text that may contain whitespace or comments, and putting a line that says
1948 @code{#NO_APP} after this text. This feature is mainly intend to support
1949 @code{asm} statements in compilers whose output is otherwise free of comments
1956 @dfn{Whitespace} is one or more blanks or tabs, in any order.
1957 Whitespace is used to separate symbols, and to make programs neater for
1958 people to read. Unless within character constants
1959 (@pxref{Characters,,Character Constants}), any whitespace means the same
1960 as exactly one space.
1966 There are two ways of rendering comments to @command{@value{AS}}. In both
1967 cases the comment is equivalent to one space.
1969 Anything from @samp{/*} through the next @samp{*/} is a comment.
1970 This means you may not nest these comments.
1974 The only way to include a newline ('\n') in a comment
1975 is to use this sort of comment.
1978 /* This sort of comment does not nest. */
1981 @cindex line comment character
1982 Anything from the @dfn{line comment} character to the next newline
1983 is considered a comment and is ignored. The line comment character is
1985 @samp{;} for the AMD 29K family;
1988 @samp{;} on the ARC;
1991 @samp{@@} on the ARM;
1994 @samp{;} for the H8/300 family;
1997 @samp{!} for the H8/500 family;
2000 @samp{;} for the HPPA;
2003 @samp{#} on the i386 and x86-64;
2006 @samp{#} on the i960;
2009 @samp{;} for the PDP-11;
2012 @samp{;} for picoJava;
2015 @samp{;} for Motorola PowerPC;
2018 @samp{!} for the Hitachi SH;
2021 @samp{!} on the SPARC;
2024 @samp{#} on the ip2k;
2027 @samp{#} on the m32r;
2030 @samp{|} on the 680x0;
2033 @samp{#} on the 68HC11 and 68HC12;
2036 @samp{;} on the M880x0;
2039 @samp{#} on the Vax;
2042 @samp{!} for the Z8000;
2045 @samp{#} on the V850;
2047 see @ref{Machine Dependencies}. @refill
2048 @c FIXME What about i860?
2051 On some machines there are two different line comment characters. One
2052 character only begins a comment if it is the first non-whitespace character on
2053 a line, while the other always begins a comment.
2057 The V850 assembler also supports a double dash as starting a comment that
2058 extends to the end of the line.
2064 @cindex lines starting with @code{#}
2065 @cindex logical line numbers
2066 To be compatible with past assemblers, lines that begin with @samp{#} have a
2067 special interpretation. Following the @samp{#} should be an absolute
2068 expression (@pxref{Expressions}): the logical line number of the @emph{next}
2069 line. Then a string (@pxref{Strings,, Strings}) is allowed: if present it is a
2070 new logical file name. The rest of the line, if any, should be whitespace.
2072 If the first non-whitespace characters on the line are not numeric,
2073 the line is ignored. (Just like a comment.)
2076 # This is an ordinary comment.
2077 # 42-6 "new_file_name" # New logical file name
2078 # This is logical line # 36.
2080 This feature is deprecated, and may disappear from future versions
2081 of @command{@value{AS}}.
2086 @cindex characters used in symbols
2087 @ifclear SPECIAL-SYMS
2088 A @dfn{symbol} is one or more characters chosen from the set of all
2089 letters (both upper and lower case), digits and the three characters
2095 A @dfn{symbol} is one or more characters chosen from the set of all
2096 letters (both upper and lower case), digits and the three characters
2097 @samp{._$}. (Save that, on the H8/300 only, you may not use @samp{$} in
2103 On most machines, you can also use @code{$} in symbol names; exceptions
2104 are noted in @ref{Machine Dependencies}.
2106 No symbol may begin with a digit. Case is significant.
2107 There is no length limit: all characters are significant. Symbols are
2108 delimited by characters not in that set, or by the beginning of a file
2109 (since the source program must end with a newline, the end of a file is
2110 not a possible symbol delimiter). @xref{Symbols}.
2111 @cindex length of symbols
2116 @cindex statements, structure of
2117 @cindex line separator character
2118 @cindex statement separator character
2120 @ifclear abnormal-separator
2121 A @dfn{statement} ends at a newline character (@samp{\n}) or at a
2122 semicolon (@samp{;}). The newline or semicolon is considered part of
2123 the preceding statement. Newlines and semicolons within character
2124 constants are an exception: they do not end statements.
2126 @ifset abnormal-separator
2128 A @dfn{statement} ends at a newline character (@samp{\n}) or an ``at''
2129 sign (@samp{@@}). The newline or at sign is considered part of the
2130 preceding statement. Newlines and at signs within character constants
2131 are an exception: they do not end statements.
2134 A @dfn{statement} ends at a newline character (@samp{\n}) or an exclamation
2135 point (@samp{!}). The newline or exclamation point is considered part of the
2136 preceding statement. Newlines and exclamation points within character
2137 constants are an exception: they do not end statements.
2140 A @dfn{statement} ends at a newline character (@samp{\n}); or (for the
2141 H8/300) a dollar sign (@samp{$}); or (for the
2144 (@samp{;}). The newline or separator character is considered part of
2145 the preceding statement. Newlines and separators within character
2146 constants are an exception: they do not end statements.
2151 A @dfn{statement} ends at a newline character (@samp{\n}) or line
2152 separator character. (The line separator is usually @samp{;}, unless
2153 this conflicts with the comment character; @pxref{Machine Dependencies}.) The
2154 newline or separator character is considered part of the preceding
2155 statement. Newlines and separators within character constants are an
2156 exception: they do not end statements.
2159 @cindex newline, required at file end
2160 @cindex EOF, newline must precede
2161 It is an error to end any statement with end-of-file: the last
2162 character of any input file should be a newline.@refill
2164 An empty statement is allowed, and may include whitespace. It is ignored.
2166 @cindex instructions and directives
2167 @cindex directives and instructions
2168 @c "key symbol" is not used elsewhere in the document; seems pedantic to
2169 @c @defn{} it in that case, as was done previously... doc@cygnus.com,
2171 A statement begins with zero or more labels, optionally followed by a
2172 key symbol which determines what kind of statement it is. The key
2173 symbol determines the syntax of the rest of the statement. If the
2174 symbol begins with a dot @samp{.} then the statement is an assembler
2175 directive: typically valid for any computer. If the symbol begins with
2176 a letter the statement is an assembly language @dfn{instruction}: it
2177 assembles into a machine language instruction.
2179 Different versions of @command{@value{AS}} for different computers
2180 recognize different instructions. In fact, the same symbol may
2181 represent a different instruction in a different computer's assembly
2185 @cindex @code{:} (label)
2186 @cindex label (@code{:})
2187 A label is a symbol immediately followed by a colon (@code{:}).
2188 Whitespace before a label or after a colon is permitted, but you may not
2189 have whitespace between a label's symbol and its colon. @xref{Labels}.
2192 For HPPA targets, labels need not be immediately followed by a colon, but
2193 the definition of a label must begin in column zero. This also implies that
2194 only one label may be defined on each line.
2198 label: .directive followed by something
2199 another_label: # This is an empty statement.
2200 instruction operand_1, operand_2, @dots{}
2207 A constant is a number, written so that its value is known by
2208 inspection, without knowing any context. Like this:
2211 .byte 74, 0112, 092, 0x4A, 0X4a, 'J, '\J # All the same value.
2212 .ascii "Ring the bell\7" # A string constant.
2213 .octa 0x123456789abcdef0123456789ABCDEF0 # A bignum.
2214 .float 0f-314159265358979323846264338327\
2215 95028841971.693993751E-40 # - pi, a flonum.
2220 * Characters:: Character Constants
2221 * Numbers:: Number Constants
2225 @subsection Character Constants
2227 @cindex character constants
2228 @cindex constants, character
2229 There are two kinds of character constants. A @dfn{character} stands
2230 for one character in one byte and its value may be used in
2231 numeric expressions. String constants (properly called string
2232 @emph{literals}) are potentially many bytes and their values may not be
2233 used in arithmetic expressions.
2237 * Chars:: Characters
2241 @subsubsection Strings
2243 @cindex string constants
2244 @cindex constants, string
2245 A @dfn{string} is written between double-quotes. It may contain
2246 double-quotes or null characters. The way to get special characters
2247 into a string is to @dfn{escape} these characters: precede them with
2248 a backslash @samp{\} character. For example @samp{\\} represents
2249 one backslash: the first @code{\} is an escape which tells
2250 @command{@value{AS}} to interpret the second character literally as a backslash
2251 (which prevents @command{@value{AS}} from recognizing the second @code{\} as an
2252 escape character). The complete list of escapes follows.
2254 @cindex escape codes, character
2255 @cindex character escape codes
2258 @c Mnemonic for ACKnowledge; for ASCII this is octal code 007.
2260 @cindex @code{\b} (backspace character)
2261 @cindex backspace (@code{\b})
2263 Mnemonic for backspace; for ASCII this is octal code 010.
2266 @c Mnemonic for EOText; for ASCII this is octal code 004.
2268 @cindex @code{\f} (formfeed character)
2269 @cindex formfeed (@code{\f})
2271 Mnemonic for FormFeed; for ASCII this is octal code 014.
2273 @cindex @code{\n} (newline character)
2274 @cindex newline (@code{\n})
2276 Mnemonic for newline; for ASCII this is octal code 012.
2279 @c Mnemonic for prefix; for ASCII this is octal code 033, usually known as @code{escape}.
2281 @cindex @code{\r} (carriage return character)
2282 @cindex carriage return (@code{\r})
2284 Mnemonic for carriage-Return; for ASCII this is octal code 015.
2287 @c Mnemonic for space; for ASCII this is octal code 040. Included for compliance with
2288 @c other assemblers.
2290 @cindex @code{\t} (tab)
2291 @cindex tab (@code{\t})
2293 Mnemonic for horizontal Tab; for ASCII this is octal code 011.
2296 @c Mnemonic for Vertical tab; for ASCII this is octal code 013.
2297 @c @item \x @var{digit} @var{digit} @var{digit}
2298 @c A hexadecimal character code. The numeric code is 3 hexadecimal digits.
2300 @cindex @code{\@var{ddd}} (octal character code)
2301 @cindex octal character code (@code{\@var{ddd}})
2302 @item \ @var{digit} @var{digit} @var{digit}
2303 An octal character code. The numeric code is 3 octal digits.
2304 For compatibility with other Unix systems, 8 and 9 are accepted as digits:
2305 for example, @code{\008} has the value 010, and @code{\009} the value 011.
2307 @cindex @code{\@var{xd...}} (hex character code)
2308 @cindex hex character code (@code{\@var{xd...}})
2309 @item \@code{x} @var{hex-digits...}
2310 A hex character code. All trailing hex digits are combined. Either upper or
2311 lower case @code{x} works.
2313 @cindex @code{\\} (@samp{\} character)
2314 @cindex backslash (@code{\\})
2316 Represents one @samp{\} character.
2319 @c Represents one @samp{'} (accent acute) character.
2320 @c This is needed in single character literals
2321 @c (@xref{Characters,,Character Constants}.) to represent
2324 @cindex @code{\"} (doublequote character)
2325 @cindex doublequote (@code{\"})
2327 Represents one @samp{"} character. Needed in strings to represent
2328 this character, because an unescaped @samp{"} would end the string.
2330 @item \ @var{anything-else}
2331 Any other character when escaped by @kbd{\} gives a warning, but
2332 assembles as if the @samp{\} was not present. The idea is that if
2333 you used an escape sequence you clearly didn't want the literal
2334 interpretation of the following character. However @command{@value{AS}} has no
2335 other interpretation, so @command{@value{AS}} knows it is giving you the wrong
2336 code and warns you of the fact.
2339 Which characters are escapable, and what those escapes represent,
2340 varies widely among assemblers. The current set is what we think
2341 the BSD 4.2 assembler recognizes, and is a subset of what most C
2342 compilers recognize. If you are in doubt, do not use an escape
2346 @subsubsection Characters
2348 @cindex single character constant
2349 @cindex character, single
2350 @cindex constant, single character
2351 A single character may be written as a single quote immediately
2352 followed by that character. The same escapes apply to characters as
2353 to strings. So if you want to write the character backslash, you
2354 must write @kbd{'\\} where the first @code{\} escapes the second
2355 @code{\}. As you can see, the quote is an acute accent, not a
2356 grave accent. A newline
2358 @ifclear abnormal-separator
2359 (or semicolon @samp{;})
2361 @ifset abnormal-separator
2363 (or at sign @samp{@@})
2366 (or dollar sign @samp{$}, for the H8/300; or semicolon @samp{;} for the
2372 immediately following an acute accent is taken as a literal character
2373 and does not count as the end of a statement. The value of a character
2374 constant in a numeric expression is the machine's byte-wide code for
2375 that character. @command{@value{AS}} assumes your character code is ASCII:
2376 @kbd{'A} means 65, @kbd{'B} means 66, and so on. @refill
2379 @subsection Number Constants
2381 @cindex constants, number
2382 @cindex number constants
2383 @command{@value{AS}} distinguishes three kinds of numbers according to how they
2384 are stored in the target machine. @emph{Integers} are numbers that
2385 would fit into an @code{int} in the C language. @emph{Bignums} are
2386 integers, but they are stored in more than 32 bits. @emph{Flonums}
2387 are floating point numbers, described below.
2390 * Integers:: Integers
2395 * Bit Fields:: Bit Fields
2401 @subsubsection Integers
2403 @cindex constants, integer
2405 @cindex binary integers
2406 @cindex integers, binary
2407 A binary integer is @samp{0b} or @samp{0B} followed by zero or more of
2408 the binary digits @samp{01}.
2410 @cindex octal integers
2411 @cindex integers, octal
2412 An octal integer is @samp{0} followed by zero or more of the octal
2413 digits (@samp{01234567}).
2415 @cindex decimal integers
2416 @cindex integers, decimal
2417 A decimal integer starts with a non-zero digit followed by zero or
2418 more digits (@samp{0123456789}).
2420 @cindex hexadecimal integers
2421 @cindex integers, hexadecimal
2422 A hexadecimal integer is @samp{0x} or @samp{0X} followed by one or
2423 more hexadecimal digits chosen from @samp{0123456789abcdefABCDEF}.
2425 Integers have the usual values. To denote a negative integer, use
2426 the prefix operator @samp{-} discussed under expressions
2427 (@pxref{Prefix Ops,,Prefix Operators}).
2430 @subsubsection Bignums
2433 @cindex constants, bignum
2434 A @dfn{bignum} has the same syntax and semantics as an integer
2435 except that the number (or its negative) takes more than 32 bits to
2436 represent in binary. The distinction is made because in some places
2437 integers are permitted while bignums are not.
2440 @subsubsection Flonums
2442 @cindex floating point numbers
2443 @cindex constants, floating point
2445 @cindex precision, floating point
2446 A @dfn{flonum} represents a floating point number. The translation is
2447 indirect: a decimal floating point number from the text is converted by
2448 @command{@value{AS}} to a generic binary floating point number of more than
2449 sufficient precision. This generic floating point number is converted
2450 to a particular computer's floating point format (or formats) by a
2451 portion of @command{@value{AS}} specialized to that computer.
2453 A flonum is written by writing (in order)
2458 (@samp{0} is optional on the HPPA.)
2462 A letter, to tell @command{@value{AS}} the rest of the number is a flonum.
2464 @kbd{e} is recommended. Case is not important.
2466 @c FIXME: verify if flonum syntax really this vague for most cases
2467 (Any otherwise illegal letter works here, but that might be changed. Vax BSD
2468 4.2 assembler seems to allow any of @samp{defghDEFGH}.)
2471 On the H8/300, H8/500,
2473 and AMD 29K architectures, the letter must be
2474 one of the letters @samp{DFPRSX} (in upper or lower case).
2476 On the ARC, the letter must be one of the letters @samp{DFRS}
2477 (in upper or lower case).
2479 On the Intel 960 architecture, the letter must be
2480 one of the letters @samp{DFT} (in upper or lower case).
2482 On the HPPA architecture, the letter must be @samp{E} (upper case only).
2486 One of the letters @samp{DFPRSX} (in upper or lower case).
2489 One of the letters @samp{DFRS} (in upper or lower case).
2492 One of the letters @samp{DFPRSX} (in upper or lower case).
2495 The letter @samp{E} (upper case only).
2498 One of the letters @samp{DFT} (in upper or lower case).
2503 An optional sign: either @samp{+} or @samp{-}.
2506 An optional @dfn{integer part}: zero or more decimal digits.
2509 An optional @dfn{fractional part}: @samp{.} followed by zero
2510 or more decimal digits.
2513 An optional exponent, consisting of:
2517 An @samp{E} or @samp{e}.
2518 @c I can't find a config where "EXP_CHARS" is other than 'eE', but in
2519 @c principle this can perfectly well be different on different targets.
2521 Optional sign: either @samp{+} or @samp{-}.
2523 One or more decimal digits.
2528 At least one of the integer part or the fractional part must be
2529 present. The floating point number has the usual base-10 value.
2531 @command{@value{AS}} does all processing using integers. Flonums are computed
2532 independently of any floating point hardware in the computer running
2533 @command{@value{AS}}.
2537 @c Bit fields are written as a general facility but are also controlled
2538 @c by a conditional-compilation flag---which is as of now (21mar91)
2539 @c turned on only by the i960 config of GAS.
2541 @subsubsection Bit Fields
2544 @cindex constants, bit field
2545 You can also define numeric constants as @dfn{bit fields}.
2546 specify two numbers separated by a colon---
2548 @var{mask}:@var{value}
2551 @command{@value{AS}} applies a bitwise @sc{and} between @var{mask} and
2554 The resulting number is then packed
2556 @c this conditional paren in case bit fields turned on elsewhere than 960
2557 (in host-dependent byte order)
2559 into a field whose width depends on which assembler directive has the
2560 bit-field as its argument. Overflow (a result from the bitwise and
2561 requiring more binary digits to represent) is not an error; instead,
2562 more constants are generated, of the specified width, beginning with the
2563 least significant digits.@refill
2565 The directives @code{.byte}, @code{.hword}, @code{.int}, @code{.long},
2566 @code{.short}, and @code{.word} accept bit-field arguments.
2571 @chapter Sections and Relocation
2576 * Secs Background:: Background
2577 * Ld Sections:: Linker Sections
2578 * As Sections:: Assembler Internal Sections
2579 * Sub-Sections:: Sub-Sections
2583 @node Secs Background
2586 Roughly, a section is a range of addresses, with no gaps; all data
2587 ``in'' those addresses is treated the same for some particular purpose.
2588 For example there may be a ``read only'' section.
2590 @cindex linker, and assembler
2591 @cindex assembler, and linker
2592 The linker @code{@value{LD}} reads many object files (partial programs) and
2593 combines their contents to form a runnable program. When @command{@value{AS}}
2594 emits an object file, the partial program is assumed to start at address 0.
2595 @code{@value{LD}} assigns the final addresses for the partial program, so that
2596 different partial programs do not overlap. This is actually an
2597 oversimplification, but it suffices to explain how @command{@value{AS}} uses
2600 @code{@value{LD}} moves blocks of bytes of your program to their run-time
2601 addresses. These blocks slide to their run-time addresses as rigid
2602 units; their length does not change and neither does the order of bytes
2603 within them. Such a rigid unit is called a @emph{section}. Assigning
2604 run-time addresses to sections is called @dfn{relocation}. It includes
2605 the task of adjusting mentions of object-file addresses so they refer to
2606 the proper run-time addresses.
2608 For the H8/300 and H8/500,
2609 and for the Hitachi SH,
2610 @command{@value{AS}} pads sections if needed to
2611 ensure they end on a word (sixteen bit) boundary.
2614 @cindex standard assembler sections
2615 An object file written by @command{@value{AS}} has at least three sections, any
2616 of which may be empty. These are named @dfn{text}, @dfn{data} and
2621 When it generates COFF output,
2623 @command{@value{AS}} can also generate whatever other named sections you specify
2624 using the @samp{.section} directive (@pxref{Section,,@code{.section}}).
2625 If you do not use any directives that place output in the @samp{.text}
2626 or @samp{.data} sections, these sections still exist, but are empty.
2631 When @command{@value{AS}} generates SOM or ELF output for the HPPA,
2633 @command{@value{AS}} can also generate whatever other named sections you
2634 specify using the @samp{.space} and @samp{.subspace} directives. See
2635 @cite{HP9000 Series 800 Assembly Language Reference Manual}
2636 (HP 92432-90001) for details on the @samp{.space} and @samp{.subspace}
2637 assembler directives.
2640 Additionally, @command{@value{AS}} uses different names for the standard
2641 text, data, and bss sections when generating SOM output. Program text
2642 is placed into the @samp{$CODE$} section, data into @samp{$DATA$}, and
2643 BSS into @samp{$BSS$}.
2647 Within the object file, the text section starts at address @code{0}, the
2648 data section follows, and the bss section follows the data section.
2651 When generating either SOM or ELF output files on the HPPA, the text
2652 section starts at address @code{0}, the data section at address
2653 @code{0x4000000}, and the bss section follows the data section.
2656 To let @code{@value{LD}} know which data changes when the sections are
2657 relocated, and how to change that data, @command{@value{AS}} also writes to the
2658 object file details of the relocation needed. To perform relocation
2659 @code{@value{LD}} must know, each time an address in the object
2663 Where in the object file is the beginning of this reference to
2666 How long (in bytes) is this reference?
2668 Which section does the address refer to? What is the numeric value of
2670 (@var{address}) @minus{} (@var{start-address of section})?
2673 Is the reference to an address ``Program-Counter relative''?
2676 @cindex addresses, format of
2677 @cindex section-relative addressing
2678 In fact, every address @command{@value{AS}} ever uses is expressed as
2680 (@var{section}) + (@var{offset into section})
2683 Further, most expressions @command{@value{AS}} computes have this section-relative
2686 (For some object formats, such as SOM for the HPPA, some expressions are
2687 symbol-relative instead.)
2690 In this manual we use the notation @{@var{secname} @var{N}@} to mean ``offset
2691 @var{N} into section @var{secname}.''
2693 Apart from text, data and bss sections you need to know about the
2694 @dfn{absolute} section. When @code{@value{LD}} mixes partial programs,
2695 addresses in the absolute section remain unchanged. For example, address
2696 @code{@{absolute 0@}} is ``relocated'' to run-time address 0 by
2697 @code{@value{LD}}. Although the linker never arranges two partial programs'
2698 data sections with overlapping addresses after linking, @emph{by definition}
2699 their absolute sections must overlap. Address @code{@{absolute@ 239@}} in one
2700 part of a program is always the same address when the program is running as
2701 address @code{@{absolute@ 239@}} in any other part of the program.
2703 The idea of sections is extended to the @dfn{undefined} section. Any
2704 address whose section is unknown at assembly time is by definition
2705 rendered @{undefined @var{U}@}---where @var{U} is filled in later.
2706 Since numbers are always defined, the only way to generate an undefined
2707 address is to mention an undefined symbol. A reference to a named
2708 common block would be such a symbol: its value is unknown at assembly
2709 time so it has section @emph{undefined}.
2711 By analogy the word @emph{section} is used to describe groups of sections in
2712 the linked program. @code{@value{LD}} puts all partial programs' text
2713 sections in contiguous addresses in the linked program. It is
2714 customary to refer to the @emph{text section} of a program, meaning all
2715 the addresses of all partial programs' text sections. Likewise for
2716 data and bss sections.
2718 Some sections are manipulated by @code{@value{LD}}; others are invented for
2719 use of @command{@value{AS}} and have no meaning except during assembly.
2722 @section Linker Sections
2723 @code{@value{LD}} deals with just four kinds of sections, summarized below.
2728 @cindex named sections
2729 @cindex sections, named
2730 @item named sections
2733 @cindex text section
2734 @cindex data section
2738 These sections hold your program. @command{@value{AS}} and @code{@value{LD}} treat them as
2739 separate but equal sections. Anything you can say of one section is
2742 When the program is running, however, it is
2743 customary for the text section to be unalterable. The
2744 text section is often shared among processes: it contains
2745 instructions, constants and the like. The data section of a running
2746 program is usually alterable: for example, C variables would be stored
2747 in the data section.
2752 This section contains zeroed bytes when your program begins running. It
2753 is used to hold uninitialized variables or common storage. The length of
2754 each partial program's bss section is important, but because it starts
2755 out containing zeroed bytes there is no need to store explicit zero
2756 bytes in the object file. The bss section was invented to eliminate
2757 those explicit zeros from object files.
2759 @cindex absolute section
2760 @item absolute section
2761 Address 0 of this section is always ``relocated'' to runtime address 0.
2762 This is useful if you want to refer to an address that @code{@value{LD}} must
2763 not change when relocating. In this sense we speak of absolute
2764 addresses being ``unrelocatable'': they do not change during relocation.
2766 @cindex undefined section
2767 @item undefined section
2768 This ``section'' is a catch-all for address references to objects not in
2769 the preceding sections.
2770 @c FIXME: ref to some other doc on obj-file formats could go here.
2773 @cindex relocation example
2774 An idealized example of three relocatable sections follows.
2776 The example uses the traditional section names @samp{.text} and @samp{.data}.
2778 Memory addresses are on the horizontal axis.
2782 @c END TEXI2ROFF-KILL
2785 partial program # 1: |ttttt|dddd|00|
2792 partial program # 2: |TTT|DDD|000|
2795 +--+---+-----+--+----+---+-----+~~
2796 linked program: | |TTT|ttttt| |dddd|DDD|00000|
2797 +--+---+-----+--+----+---+-----+~~
2799 addresses: 0 @dots{}
2806 \line{\it Partial program \#1: \hfil}
2807 \line{\ibox{2.5cm}{\tt text}\ibox{2cm}{\tt data}\ibox{1cm}{\tt bss}\hfil}
2808 \line{\boxit{2.5cm}{\tt ttttt}\boxit{2cm}{\tt dddd}\boxit{1cm}{\tt 00}\hfil}
2810 \line{\it Partial program \#2: \hfil}
2811 \line{\ibox{1cm}{\tt text}\ibox{1.5cm}{\tt data}\ibox{1cm}{\tt bss}\hfil}
2812 \line{\boxit{1cm}{\tt TTT}\boxit{1.5cm}{\tt DDDD}\boxit{1cm}{\tt 000}\hfil}
2814 \line{\it linked program: \hfil}
2815 \line{\ibox{.5cm}{}\ibox{1cm}{\tt text}\ibox{2.5cm}{}\ibox{.75cm}{}\ibox{2cm}{\tt data}\ibox{1.5cm}{}\ibox{2cm}{\tt bss}\hfil}
2816 \line{\boxit{.5cm}{}\boxit{1cm}{\tt TTT}\boxit{2.5cm}{\tt
2817 ttttt}\boxit{.75cm}{}\boxit{2cm}{\tt dddd}\boxit{1.5cm}{\tt
2818 DDDD}\boxit{2cm}{\tt 00000}\ \dots\hfil}
2820 \line{\it addresses: \hfil}
2824 @c END TEXI2ROFF-KILL
2827 @section Assembler Internal Sections
2829 @cindex internal assembler sections
2830 @cindex sections in messages, internal
2831 These sections are meant only for the internal use of @command{@value{AS}}. They
2832 have no meaning at run-time. You do not really need to know about these
2833 sections for most purposes; but they can be mentioned in @command{@value{AS}}
2834 warning messages, so it might be helpful to have an idea of their
2835 meanings to @command{@value{AS}}. These sections are used to permit the
2836 value of every expression in your assembly language program to be a
2837 section-relative address.
2840 @cindex assembler internal logic error
2841 @item ASSEMBLER-INTERNAL-LOGIC-ERROR!
2842 An internal assembler logic error has been found. This means there is a
2843 bug in the assembler.
2845 @cindex expr (internal section)
2847 The assembler stores complex expression internally as combinations of
2848 symbols. When it needs to represent an expression as a symbol, it puts
2849 it in the expr section.
2851 @c FIXME item transfer[t] vector preload
2852 @c FIXME item transfer[t] vector postload
2853 @c FIXME item register
2857 @section Sub-Sections
2859 @cindex numbered subsections
2860 @cindex grouping data
2866 fall into two sections: text and data.
2868 You may have separate groups of
2870 data in named sections
2874 data in named sections
2880 that you want to end up near to each other in the object file, even though they
2881 are not contiguous in the assembler source. @command{@value{AS}} allows you to
2882 use @dfn{subsections} for this purpose. Within each section, there can be
2883 numbered subsections with values from 0 to 8192. Objects assembled into the
2884 same subsection go into the object file together with other objects in the same
2885 subsection. For example, a compiler might want to store constants in the text
2886 section, but might not want to have them interspersed with the program being
2887 assembled. In this case, the compiler could issue a @samp{.text 0} before each
2888 section of code being output, and a @samp{.text 1} before each group of
2889 constants being output.
2891 Subsections are optional. If you do not use subsections, everything
2892 goes in subsection number zero.
2895 Each subsection is zero-padded up to a multiple of four bytes.
2896 (Subsections may be padded a different amount on different flavors
2897 of @command{@value{AS}}.)
2901 On the H8/300 and H8/500 platforms, each subsection is zero-padded to a word
2902 boundary (two bytes).
2903 The same is true on the Hitachi SH.
2906 @c FIXME section padding (alignment)?
2907 @c Rich Pixley says padding here depends on target obj code format; that
2908 @c doesn't seem particularly useful to say without further elaboration,
2909 @c so for now I say nothing about it. If this is a generic BFD issue,
2910 @c these paragraphs might need to vanish from this manual, and be
2911 @c discussed in BFD chapter of binutils (or some such).
2914 On the AMD 29K family, no particular padding is added to section or
2915 subsection sizes; @value{AS} forces no alignment on this platform.
2919 Subsections appear in your object file in numeric order, lowest numbered
2920 to highest. (All this to be compatible with other people's assemblers.)
2921 The object file contains no representation of subsections; @code{@value{LD}} and
2922 other programs that manipulate object files see no trace of them.
2923 They just see all your text subsections as a text section, and all your
2924 data subsections as a data section.
2926 To specify which subsection you want subsequent statements assembled
2927 into, use a numeric argument to specify it, in a @samp{.text
2928 @var{expression}} or a @samp{.data @var{expression}} statement.
2931 When generating COFF output, you
2936 can also use an extra subsection
2937 argument with arbitrary named sections: @samp{.section @var{name},
2940 @var{Expression} should be an absolute expression.
2941 (@xref{Expressions}.) If you just say @samp{.text} then @samp{.text 0}
2942 is assumed. Likewise @samp{.data} means @samp{.data 0}. Assembly
2943 begins in @code{text 0}. For instance:
2945 .text 0 # The default subsection is text 0 anyway.
2946 .ascii "This lives in the first text subsection. *"
2948 .ascii "But this lives in the second text subsection."
2950 .ascii "This lives in the data section,"
2951 .ascii "in the first data subsection."
2953 .ascii "This lives in the first text section,"
2954 .ascii "immediately following the asterisk (*)."
2957 Each section has a @dfn{location counter} incremented by one for every byte
2958 assembled into that section. Because subsections are merely a convenience
2959 restricted to @command{@value{AS}} there is no concept of a subsection location
2960 counter. There is no way to directly manipulate a location counter---but the
2961 @code{.align} directive changes it, and any label definition captures its
2962 current value. The location counter of the section where statements are being
2963 assembled is said to be the @dfn{active} location counter.
2966 @section bss Section
2969 @cindex common variable storage
2970 The bss section is used for local common variable storage.
2971 You may allocate address space in the bss section, but you may
2972 not dictate data to load into it before your program executes. When
2973 your program starts running, all the contents of the bss
2974 section are zeroed bytes.
2976 The @code{.lcomm} pseudo-op defines a symbol in the bss section; see
2977 @ref{Lcomm,,@code{.lcomm}}.
2979 The @code{.comm} pseudo-op may be used to declare a common symbol, which is
2980 another form of uninitialized symbol; see @xref{Comm,,@code{.comm}}.
2983 When assembling for a target which supports multiple sections, such as ELF or
2984 COFF, you may switch into the @code{.bss} section and define symbols as usual;
2985 see @ref{Section,,@code{.section}}. You may only assemble zero values into the
2986 section. Typically the section will only contain symbol definitions and
2987 @code{.skip} directives (@pxref{Skip,,@code{.skip}}).
2994 Symbols are a central concept: the programmer uses symbols to name
2995 things, the linker uses symbols to link, and the debugger uses symbols
2999 @cindex debuggers, and symbol order
3000 @emph{Warning:} @command{@value{AS}} does not place symbols in the object file in
3001 the same order they were declared. This may break some debuggers.
3006 * Setting Symbols:: Giving Symbols Other Values
3007 * Symbol Names:: Symbol Names
3008 * Dot:: The Special Dot Symbol
3009 * Symbol Attributes:: Symbol Attributes
3016 A @dfn{label} is written as a symbol immediately followed by a colon
3017 @samp{:}. The symbol then represents the current value of the
3018 active location counter, and is, for example, a suitable instruction
3019 operand. You are warned if you use the same symbol to represent two
3020 different locations: the first definition overrides any other
3024 On the HPPA, the usual form for a label need not be immediately followed by a
3025 colon, but instead must start in column zero. Only one label may be defined on
3026 a single line. To work around this, the HPPA version of @command{@value{AS}} also
3027 provides a special directive @code{.label} for defining labels more flexibly.
3030 @node Setting Symbols
3031 @section Giving Symbols Other Values
3033 @cindex assigning values to symbols
3034 @cindex symbol values, assigning
3035 A symbol can be given an arbitrary value by writing a symbol, followed
3036 by an equals sign @samp{=}, followed by an expression
3037 (@pxref{Expressions}). This is equivalent to using the @code{.set}
3038 directive. @xref{Set,,@code{.set}}.
3041 @section Symbol Names
3043 @cindex symbol names
3044 @cindex names, symbol
3045 @ifclear SPECIAL-SYMS
3046 Symbol names begin with a letter or with one of @samp{._}. On most
3047 machines, you can also use @code{$} in symbol names; exceptions are
3048 noted in @ref{Machine Dependencies}. That character may be followed by any
3049 string of digits, letters, dollar signs (unless otherwise noted in
3050 @ref{Machine Dependencies}), and underscores.
3053 For the AMD 29K family, @samp{?} is also allowed in the
3054 body of a symbol name, though not at its beginning.
3059 Symbol names begin with a letter or with one of @samp{._}. On the
3061 H8/500, you can also use @code{$} in symbol names. That character may
3062 be followed by any string of digits, letters, dollar signs (save on the
3063 H8/300), and underscores.
3067 Case of letters is significant: @code{foo} is a different symbol name
3070 Each symbol has exactly one name. Each name in an assembly language program
3071 refers to exactly one symbol. You may use that symbol name any number of times
3074 @subheading Local Symbol Names
3076 @cindex local symbol names
3077 @cindex symbol names, local
3078 @cindex temporary symbol names
3079 @cindex symbol names, temporary
3080 Local symbols help compilers and programmers use names temporarily.
3081 They create symbols which are guaranteed to be unique over the entire scope of
3082 the input source code and which can be referred to by a simple notation.
3083 To define a local symbol, write a label of the form @samp{@b{N}:} (where @b{N}
3084 represents any positive integer). To refer to the most recent previous
3085 definition of that symbol write @samp{@b{N}b}, using the same number as when
3086 you defined the label. To refer to the next definition of a local label, write
3087 @samp{@b{N}f}--- The @samp{b} stands for``backwards'' and the @samp{f} stands
3090 There is no restriction on how you can use these labels, and you can reuse them
3091 too. So that it is possible to repeatedly define the same local label (using
3092 the same number @samp{@b{N}}), although you can only refer to the most recently
3093 defined local label of that number (for a backwards reference) or the next
3094 definition of a specific local label for a forward reference. It is also worth
3095 noting that the first 10 local labels (@samp{@b{0:}}@dots{}@samp{@b{9:}}) are
3096 implemented in a slightly more efficient manner than the others.
3107 Which is the equivalent of:
3110 label_1: branch label_3
3111 label_2: branch label_1
3112 label_3: branch label_4
3113 label_4: branch label_3
3116 Local symbol names are only a notational device. They are immediately
3117 transformed into more conventional symbol names before the assembler uses them.
3118 The symbol names stored in the symbol table, appearing in error messages and
3119 optionally emitted to the object file. The names are constructed using these
3124 All local labels begin with @samp{L}. Normally both @command{@value{AS}} and
3125 @code{@value{LD}} forget symbols that start with @samp{L}. These labels are
3126 used for symbols you are never intended to see. If you use the
3127 @samp{-L} option then @command{@value{AS}} retains these symbols in the
3128 object file. If you also instruct @code{@value{LD}} to retain these symbols,
3129 you may use them in debugging.
3132 This is the number that was used in the local label definition. So if the
3133 label is written @samp{55:} then the number is @samp{55}.
3136 This unusual character is included so you do not accidentally invent a symbol
3137 of the same name. The character has ASCII value of @samp{\002} (control-B).
3139 @item @emph{ordinal number}
3140 This is a serial number to keep the labels distinct. The first definition of
3141 @samp{0:} gets the number @samp{1}. The 15th definition of @samp{0:} gets the
3142 number @samp{15}, and so on. Likewise the first definition of @samp{1:} gets
3143 the number @samp{1} and its 15th defintion gets @samp{15} as well.
3146 So for example, the first @code{1:} is named @code{L1@kbd{C-B}1}, the 44th
3147 @code{3:} is named @code{L3@kbd{C-B}44}.
3149 @subheading Dollar Local Labels
3150 @cindex dollar local symbols
3152 @code{@value{AS}} also supports an even more local form of local labels called
3153 dollar labels. These labels go out of scope (ie they become undefined) as soon
3154 as a non-local label is defined. Thus they remain valid for only a small
3155 region of the input source code. Normal local labels, by contrast, remain in
3156 scope for the entire file, or until they are redefined by another occurrence of
3157 the same local label.
3159 Dollar labels are defined in exactly the same way as ordinary local labels,
3160 except that instead of being terminated by a colon, they are terminated by a
3161 dollar sign. eg @samp{@b{55$}}.
3163 They can also be distinguished from ordinary local labels by their transformed
3164 name which uses ASCII character @samp{\001} (control-A) as the magic character
3165 to distinguish them from ordinary labels. Thus the 5th defintion of @samp{6$}
3166 is named @samp{L6@kbd{C-A}5}.
3169 @section The Special Dot Symbol
3171 @cindex dot (symbol)
3172 @cindex @code{.} (symbol)
3173 @cindex current address
3174 @cindex location counter
3175 The special symbol @samp{.} refers to the current address that
3176 @command{@value{AS}} is assembling into. Thus, the expression @samp{melvin:
3177 .long .} defines @code{melvin} to contain its own address.
3178 Assigning a value to @code{.} is treated the same as a @code{.org}
3179 directive. Thus, the expression @samp{.=.+4} is the same as saying
3180 @ifclear no-space-dir
3189 @node Symbol Attributes
3190 @section Symbol Attributes
3192 @cindex symbol attributes
3193 @cindex attributes, symbol
3194 Every symbol has, as well as its name, the attributes ``Value'' and
3195 ``Type''. Depending on output format, symbols can also have auxiliary
3198 The detailed definitions are in @file{a.out.h}.
3201 If you use a symbol without defining it, @command{@value{AS}} assumes zero for
3202 all these attributes, and probably won't warn you. This makes the
3203 symbol an externally defined symbol, which is generally what you
3207 * Symbol Value:: Value
3208 * Symbol Type:: Type
3211 * a.out Symbols:: Symbol Attributes: @code{a.out}
3215 * a.out Symbols:: Symbol Attributes: @code{a.out}
3218 * a.out Symbols:: Symbol Attributes: @code{a.out}, @code{b.out}
3223 * COFF Symbols:: Symbol Attributes for COFF
3226 * SOM Symbols:: Symbol Attributes for SOM
3233 @cindex value of a symbol
3234 @cindex symbol value
3235 The value of a symbol is (usually) 32 bits. For a symbol which labels a
3236 location in the text, data, bss or absolute sections the value is the
3237 number of addresses from the start of that section to the label.
3238 Naturally for text, data and bss sections the value of a symbol changes
3239 as @code{@value{LD}} changes section base addresses during linking. Absolute
3240 symbols' values do not change during linking: that is why they are
3243 The value of an undefined symbol is treated in a special way. If it is
3244 0 then the symbol is not defined in this assembler source file, and
3245 @code{@value{LD}} tries to determine its value from other files linked into the
3246 same program. You make this kind of symbol simply by mentioning a symbol
3247 name without defining it. A non-zero value represents a @code{.comm}
3248 common declaration. The value is how much common storage to reserve, in
3249 bytes (addresses). The symbol refers to the first address of the
3255 @cindex type of a symbol
3257 The type attribute of a symbol contains relocation (section)
3258 information, any flag settings indicating that a symbol is external, and
3259 (optionally), other information for linkers and debuggers. The exact
3260 format depends on the object-code output format in use.
3265 @c The following avoids a "widow" subsection title. @group would be
3266 @c better if it were available outside examples.
3269 @subsection Symbol Attributes: @code{a.out}, @code{b.out}
3271 @cindex @code{b.out} symbol attributes
3272 @cindex symbol attributes, @code{b.out}
3273 These symbol attributes appear only when @command{@value{AS}} is configured for
3274 one of the Berkeley-descended object output formats---@code{a.out} or
3280 @subsection Symbol Attributes: @code{a.out}
3282 @cindex @code{a.out} symbol attributes
3283 @cindex symbol attributes, @code{a.out}
3289 @subsection Symbol Attributes: @code{a.out}
3291 @cindex @code{a.out} symbol attributes
3292 @cindex symbol attributes, @code{a.out}
3296 * Symbol Desc:: Descriptor
3297 * Symbol Other:: Other
3301 @subsubsection Descriptor
3303 @cindex descriptor, of @code{a.out} symbol
3304 This is an arbitrary 16-bit value. You may establish a symbol's
3305 descriptor value by using a @code{.desc} statement
3306 (@pxref{Desc,,@code{.desc}}). A descriptor value means nothing to
3307 @command{@value{AS}}.
3310 @subsubsection Other
3312 @cindex other attribute, of @code{a.out} symbol
3313 This is an arbitrary 8-bit value. It means nothing to @command{@value{AS}}.
3318 @subsection Symbol Attributes for COFF
3320 @cindex COFF symbol attributes
3321 @cindex symbol attributes, COFF
3323 The COFF format supports a multitude of auxiliary symbol attributes;
3324 like the primary symbol attributes, they are set between @code{.def} and
3325 @code{.endef} directives.
3327 @subsubsection Primary Attributes
3329 @cindex primary attributes, COFF symbols
3330 The symbol name is set with @code{.def}; the value and type,
3331 respectively, with @code{.val} and @code{.type}.
3333 @subsubsection Auxiliary Attributes
3335 @cindex auxiliary attributes, COFF symbols
3336 The @command{@value{AS}} directives @code{.dim}, @code{.line}, @code{.scl},
3337 @code{.size}, and @code{.tag} can generate auxiliary symbol table
3338 information for COFF.
3343 @subsection Symbol Attributes for SOM
3345 @cindex SOM symbol attributes
3346 @cindex symbol attributes, SOM
3348 The SOM format for the HPPA supports a multitude of symbol attributes set with
3349 the @code{.EXPORT} and @code{.IMPORT} directives.
3351 The attributes are described in @cite{HP9000 Series 800 Assembly
3352 Language Reference Manual} (HP 92432-90001) under the @code{IMPORT} and
3353 @code{EXPORT} assembler directive documentation.
3357 @chapter Expressions
3361 @cindex numeric values
3362 An @dfn{expression} specifies an address or numeric value.
3363 Whitespace may precede and/or follow an expression.
3365 The result of an expression must be an absolute number, or else an offset into
3366 a particular section. If an expression is not absolute, and there is not
3367 enough information when @command{@value{AS}} sees the expression to know its
3368 section, a second pass over the source program might be necessary to interpret
3369 the expression---but the second pass is currently not implemented.
3370 @command{@value{AS}} aborts with an error message in this situation.
3373 * Empty Exprs:: Empty Expressions
3374 * Integer Exprs:: Integer Expressions
3378 @section Empty Expressions
3380 @cindex empty expressions
3381 @cindex expressions, empty
3382 An empty expression has no value: it is just whitespace or null.
3383 Wherever an absolute expression is required, you may omit the
3384 expression, and @command{@value{AS}} assumes a value of (absolute) 0. This
3385 is compatible with other assemblers.
3388 @section Integer Expressions
3390 @cindex integer expressions
3391 @cindex expressions, integer
3392 An @dfn{integer expression} is one or more @emph{arguments} delimited
3393 by @emph{operators}.
3396 * Arguments:: Arguments
3397 * Operators:: Operators
3398 * Prefix Ops:: Prefix Operators
3399 * Infix Ops:: Infix Operators
3403 @subsection Arguments
3405 @cindex expression arguments
3406 @cindex arguments in expressions
3407 @cindex operands in expressions
3408 @cindex arithmetic operands
3409 @dfn{Arguments} are symbols, numbers or subexpressions. In other
3410 contexts arguments are sometimes called ``arithmetic operands''. In
3411 this manual, to avoid confusing them with the ``instruction operands'' of
3412 the machine language, we use the term ``argument'' to refer to parts of
3413 expressions only, reserving the word ``operand'' to refer only to machine
3414 instruction operands.
3416 Symbols are evaluated to yield @{@var{section} @var{NNN}@} where
3417 @var{section} is one of text, data, bss, absolute,
3418 or undefined. @var{NNN} is a signed, 2's complement 32 bit
3421 Numbers are usually integers.
3423 A number can be a flonum or bignum. In this case, you are warned
3424 that only the low order 32 bits are used, and @command{@value{AS}} pretends
3425 these 32 bits are an integer. You may write integer-manipulating
3426 instructions that act on exotic constants, compatible with other
3429 @cindex subexpressions
3430 Subexpressions are a left parenthesis @samp{(} followed by an integer
3431 expression, followed by a right parenthesis @samp{)}; or a prefix
3432 operator followed by an argument.
3435 @subsection Operators
3437 @cindex operators, in expressions
3438 @cindex arithmetic functions
3439 @cindex functions, in expressions
3440 @dfn{Operators} are arithmetic functions, like @code{+} or @code{%}. Prefix
3441 operators are followed by an argument. Infix operators appear
3442 between their arguments. Operators may be preceded and/or followed by
3446 @subsection Prefix Operator
3448 @cindex prefix operators
3449 @command{@value{AS}} has the following @dfn{prefix operators}. They each take
3450 one argument, which must be absolute.
3452 @c the tex/end tex stuff surrounding this small table is meant to make
3453 @c it align, on the printed page, with the similar table in the next
3454 @c section (which is inside an enumerate).
3456 \global\advance\leftskip by \itemindent
3461 @dfn{Negation}. Two's complement negation.
3463 @dfn{Complementation}. Bitwise not.
3467 \global\advance\leftskip by -\itemindent
3471 @subsection Infix Operators
3473 @cindex infix operators
3474 @cindex operators, permitted arguments
3475 @dfn{Infix operators} take two arguments, one on either side. Operators
3476 have precedence, but operations with equal precedence are performed left
3477 to right. Apart from @code{+} or @option{-}, both arguments must be
3478 absolute, and the result is absolute.
3481 @cindex operator precedence
3482 @cindex precedence of operators
3489 @dfn{Multiplication}.
3492 @dfn{Division}. Truncation is the same as the C operator @samp{/}
3499 @dfn{Shift Left}. Same as the C operator @samp{<<}.
3503 @dfn{Shift Right}. Same as the C operator @samp{>>}.
3507 Intermediate precedence
3512 @dfn{Bitwise Inclusive Or}.
3518 @dfn{Bitwise Exclusive Or}.
3521 @dfn{Bitwise Or Not}.
3528 @cindex addition, permitted arguments
3529 @cindex plus, permitted arguments
3530 @cindex arguments for addition
3532 @dfn{Addition}. If either argument is absolute, the result has the section of
3533 the other argument. You may not add together arguments from different
3536 @cindex subtraction, permitted arguments
3537 @cindex minus, permitted arguments
3538 @cindex arguments for subtraction
3540 @dfn{Subtraction}. If the right argument is absolute, the
3541 result has the section of the left argument.
3542 If both arguments are in the same section, the result is absolute.
3543 You may not subtract arguments from different sections.
3544 @c FIXME is there still something useful to say about undefined - undefined ?
3546 @cindex comparison expressions
3547 @cindex expressions, comparison
3551 @dfn{Is Not Equal To}
3555 @dfn{Is Greater Than}
3557 @dfn{Is Greater Than Or Equal To}
3559 @dfn{Is Less Than Or Equal To}
3561 The comparison operators can be used as infix operators. A true results has a
3562 value of -1 whereas a false result has a value of 0. Note, these operators
3563 perform signed comparisons.
3566 @item Lowest Precedence
3575 These two logical operations can be used to combine the results of sub
3576 expressions. Note, unlike the comparison operators a true result returns a
3577 value of 1 but a false results does still return 0. Also note that the logical
3578 or operator has a slightly lower precedence than logical and.
3583 In short, it's only meaningful to add or subtract the @emph{offsets} in an
3584 address; you can only have a defined section in one of the two arguments.
3587 @chapter Assembler Directives
3589 @cindex directives, machine independent
3590 @cindex pseudo-ops, machine independent
3591 @cindex machine independent directives
3592 All assembler directives have names that begin with a period (@samp{.}).
3593 The rest of the name is letters, usually in lower case.
3595 This chapter discusses directives that are available regardless of the
3596 target machine configuration for the @sc{gnu} assembler.
3598 Some machine configurations provide additional directives.
3599 @xref{Machine Dependencies}.
3602 @ifset machine-directives
3603 @xref{Machine Dependencies} for additional directives.
3608 * Abort:: @code{.abort}
3610 * ABORT:: @code{.ABORT}
3613 * Align:: @code{.align @var{abs-expr} , @var{abs-expr}}
3614 * Ascii:: @code{.ascii "@var{string}"}@dots{}
3615 * Asciz:: @code{.asciz "@var{string}"}@dots{}
3616 * Balign:: @code{.balign @var{abs-expr} , @var{abs-expr}}
3617 * Byte:: @code{.byte @var{expressions}}
3618 * Comm:: @code{.comm @var{symbol} , @var{length} }
3619 * Data:: @code{.data @var{subsection}}
3621 * Def:: @code{.def @var{name}}
3624 * Desc:: @code{.desc @var{symbol}, @var{abs-expression}}
3630 * Double:: @code{.double @var{flonums}}
3631 * Eject:: @code{.eject}
3632 * Else:: @code{.else}
3633 * Elseif:: @code{.elseif}
3636 * Endef:: @code{.endef}
3639 * Endfunc:: @code{.endfunc}
3640 * Endif:: @code{.endif}
3641 * Equ:: @code{.equ @var{symbol}, @var{expression}}
3642 * Equiv:: @code{.equiv @var{symbol}, @var{expression}}
3644 * Exitm:: @code{.exitm}
3645 * Extern:: @code{.extern}
3646 * Fail:: @code{.fail}
3647 @ifclear no-file-dir
3648 * File:: @code{.file @var{string}}
3651 * Fill:: @code{.fill @var{repeat} , @var{size} , @var{value}}
3652 * Float:: @code{.float @var{flonums}}
3653 * Func:: @code{.func}
3654 * Global:: @code{.global @var{symbol}}, @code{.globl @var{symbol}}
3656 * Hidden:: @code{.hidden @var{names}}
3659 * hword:: @code{.hword @var{expressions}}
3660 * Ident:: @code{.ident}
3661 * If:: @code{.if @var{absolute expression}}
3662 * Incbin:: @code{.incbin "@var{file}"[,@var{skip}[,@var{count}]]}
3663 * Include:: @code{.include "@var{file}"}
3664 * Int:: @code{.int @var{expressions}}
3666 * Internal:: @code{.internal @var{names}}
3669 * Irp:: @code{.irp @var{symbol},@var{values}}@dots{}
3670 * Irpc:: @code{.irpc @var{symbol},@var{values}}@dots{}
3671 * Lcomm:: @code{.lcomm @var{symbol} , @var{length}}
3672 * Lflags:: @code{.lflags}
3673 @ifclear no-line-dir
3674 * Line:: @code{.line @var{line-number}}
3677 * Ln:: @code{.ln @var{line-number}}
3678 * Linkonce:: @code{.linkonce [@var{type}]}
3679 * List:: @code{.list}
3680 * Long:: @code{.long @var{expressions}}
3682 * Lsym:: @code{.lsym @var{symbol}, @var{expression}}
3685 * Macro:: @code{.macro @var{name} @var{args}}@dots{}
3686 * MRI:: @code{.mri @var{val}}
3687 * Nolist:: @code{.nolist}
3688 * Octa:: @code{.octa @var{bignums}}
3689 * Org:: @code{.org @var{new-lc} , @var{fill}}
3690 * P2align:: @code{.p2align @var{abs-expr} , @var{abs-expr}}
3692 * PopSection:: @code{.popsection}
3693 * Previous:: @code{.previous}
3696 * Print:: @code{.print @var{string}}
3698 * Protected:: @code{.protected @var{names}}
3701 * Psize:: @code{.psize @var{lines}, @var{columns}}
3702 * Purgem:: @code{.purgem @var{name}}
3704 * PushSection:: @code{.pushsection @var{name}}
3707 * Quad:: @code{.quad @var{bignums}}
3708 * Rept:: @code{.rept @var{count}}
3709 * Sbttl:: @code{.sbttl "@var{subheading}"}
3711 * Scl:: @code{.scl @var{class}}
3712 * Section:: @code{.section @var{name}, @var{subsection}}
3715 * Set:: @code{.set @var{symbol}, @var{expression}}
3716 * Short:: @code{.short @var{expressions}}
3717 * Single:: @code{.single @var{flonums}}
3718 * Size:: @code{.size [@var{name} , @var{expression}]}
3719 * Skip:: @code{.skip @var{size} , @var{fill}}
3720 * Sleb128:: @code{.sleb128 @var{expressions}}
3721 * Space:: @code{.space @var{size} , @var{fill}}
3723 * Stab:: @code{.stabd, .stabn, .stabs}
3726 * String:: @code{.string "@var{str}"}
3727 * Struct:: @code{.struct @var{expression}}
3729 * SubSection:: @code{.subsection}
3730 * Symver:: @code{.symver @var{name},@var{name2@@nodename}}
3734 * Tag:: @code{.tag @var{structname}}
3737 * Text:: @code{.text @var{subsection}}
3738 * Title:: @code{.title "@var{heading}"}
3739 * Type:: @code{.type <@var{int} | @var{name} , @var{type description}>}
3740 * Uleb128:: @code{.uleb128 @var{expressions}}
3742 * Val:: @code{.val @var{addr}}
3746 * Version:: @code{.version "@var{string}"}
3747 * VTableEntry:: @code{.vtable_entry @var{table}, @var{offset}}
3748 * VTableInherit:: @code{.vtable_inherit @var{child}, @var{parent}}
3749 * Weak:: @code{.weak @var{names}}
3752 * Word:: @code{.word @var{expressions}}
3753 * Deprecated:: Deprecated Directives
3757 @section @code{.abort}
3759 @cindex @code{abort} directive
3760 @cindex stopping the assembly
3761 This directive stops the assembly immediately. It is for
3762 compatibility with other assemblers. The original idea was that the
3763 assembly language source would be piped into the assembler. If the sender
3764 of the source quit, it could use this directive tells @command{@value{AS}} to
3765 quit also. One day @code{.abort} will not be supported.
3769 @section @code{.ABORT}
3771 @cindex @code{ABORT} directive
3772 When producing COFF output, @command{@value{AS}} accepts this directive as a
3773 synonym for @samp{.abort}.
3776 When producing @code{b.out} output, @command{@value{AS}} accepts this directive,
3782 @section @code{.align @var{abs-expr}, @var{abs-expr}, @var{abs-expr}}
3784 @cindex padding the location counter
3785 @cindex @code{align} directive
3786 Pad the location counter (in the current subsection) to a particular storage
3787 boundary. The first expression (which must be absolute) is the alignment
3788 required, as described below.
3790 The second expression (also absolute) gives the fill value to be stored in the
3791 padding bytes. It (and the comma) may be omitted. If it is omitted, the
3792 padding bytes are normally zero. However, on some systems, if the section is
3793 marked as containing code and the fill value is omitted, the space is filled
3794 with no-op instructions.
3796 The third expression is also absolute, and is also optional. If it is present,
3797 it is the maximum number of bytes that should be skipped by this alignment
3798 directive. If doing the alignment would require skipping more bytes than the
3799 specified maximum, then the alignment is not done at all. You can omit the
3800 fill value (the second argument) entirely by simply using two commas after the
3801 required alignment; this can be useful if you want the alignment to be filled
3802 with no-op instructions when appropriate.
3804 The way the required alignment is specified varies from system to system.
3805 For the a29k, hppa, m68k, m88k, w65, sparc, and Hitachi SH, and i386 using ELF
3807 the first expression is the
3808 alignment request in bytes. For example @samp{.align 8} advances
3809 the location counter until it is a multiple of 8. If the location counter
3810 is already a multiple of 8, no change is needed.
3812 For other systems, including the i386 using a.out format, and the arm and
3813 strongarm, it is the
3814 number of low-order zero bits the location counter must have after
3815 advancement. For example @samp{.align 3} advances the location
3816 counter until it a multiple of 8. If the location counter is already a
3817 multiple of 8, no change is needed.
3819 This inconsistency is due to the different behaviors of the various
3820 native assemblers for these systems which GAS must emulate.
3821 GAS also provides @code{.balign} and @code{.p2align} directives,
3822 described later, which have a consistent behavior across all
3823 architectures (but are specific to GAS).
3826 @section @code{.ascii "@var{string}"}@dots{}
3828 @cindex @code{ascii} directive
3829 @cindex string literals
3830 @code{.ascii} expects zero or more string literals (@pxref{Strings})
3831 separated by commas. It assembles each string (with no automatic
3832 trailing zero byte) into consecutive addresses.
3835 @section @code{.asciz "@var{string}"}@dots{}
3837 @cindex @code{asciz} directive
3838 @cindex zero-terminated strings
3839 @cindex null-terminated strings
3840 @code{.asciz} is just like @code{.ascii}, but each string is followed by
3841 a zero byte. The ``z'' in @samp{.asciz} stands for ``zero''.
3844 @section @code{.balign[wl] @var{abs-expr}, @var{abs-expr}, @var{abs-expr}}
3846 @cindex padding the location counter given number of bytes
3847 @cindex @code{balign} directive
3848 Pad the location counter (in the current subsection) to a particular
3849 storage boundary. The first expression (which must be absolute) is the
3850 alignment request in bytes. For example @samp{.balign 8} advances
3851 the location counter until it is a multiple of 8. If the location counter
3852 is already a multiple of 8, no change is needed.
3854 The second expression (also absolute) gives the fill value to be stored in the
3855 padding bytes. It (and the comma) may be omitted. If it is omitted, the
3856 padding bytes are normally zero. However, on some systems, if the section is
3857 marked as containing code and the fill value is omitted, the space is filled
3858 with no-op instructions.
3860 The third expression is also absolute, and is also optional. If it is present,
3861 it is the maximum number of bytes that should be skipped by this alignment
3862 directive. If doing the alignment would require skipping more bytes than the
3863 specified maximum, then the alignment is not done at all. You can omit the
3864 fill value (the second argument) entirely by simply using two commas after the
3865 required alignment; this can be useful if you want the alignment to be filled
3866 with no-op instructions when appropriate.
3868 @cindex @code{balignw} directive
3869 @cindex @code{balignl} directive
3870 The @code{.balignw} and @code{.balignl} directives are variants of the
3871 @code{.balign} directive. The @code{.balignw} directive treats the fill
3872 pattern as a two byte word value. The @code{.balignl} directives treats the
3873 fill pattern as a four byte longword value. For example, @code{.balignw
3874 4,0x368d} will align to a multiple of 4. If it skips two bytes, they will be
3875 filled in with the value 0x368d (the exact placement of the bytes depends upon
3876 the endianness of the processor). If it skips 1 or 3 bytes, the fill value is
3880 @section @code{.byte @var{expressions}}
3882 @cindex @code{byte} directive
3883 @cindex integers, one byte
3884 @code{.byte} expects zero or more expressions, separated by commas.
3885 Each expression is assembled into the next byte.
3888 @section @code{.comm @var{symbol} , @var{length} }
3890 @cindex @code{comm} directive
3891 @cindex symbol, common
3892 @code{.comm} declares a common symbol named @var{symbol}. When linking, a
3893 common symbol in one object file may be merged with a defined or common symbol
3894 of the same name in another object file. If @code{@value{LD}} does not see a
3895 definition for the symbol--just one or more common symbols--then it will
3896 allocate @var{length} bytes of uninitialized memory. @var{length} must be an
3897 absolute expression. If @code{@value{LD}} sees multiple common symbols with
3898 the same name, and they do not all have the same size, it will allocate space
3899 using the largest size.
3902 When using ELF, the @code{.comm} directive takes an optional third argument.
3903 This is the desired alignment of the symbol, specified as a byte boundary (for
3904 example, an alignment of 16 means that the least significant 4 bits of the
3905 address should be zero). The alignment must be an absolute expression, and it
3906 must be a power of two. If @code{@value{LD}} allocates uninitialized memory
3907 for the common symbol, it will use the alignment when placing the symbol. If
3908 no alignment is specified, @command{@value{AS}} will set the alignment to the
3909 largest power of two less than or equal to the size of the symbol, up to a
3914 The syntax for @code{.comm} differs slightly on the HPPA. The syntax is
3915 @samp{@var{symbol} .comm, @var{length}}; @var{symbol} is optional.
3919 @section @code{.data @var{subsection}}
3921 @cindex @code{data} directive
3922 @code{.data} tells @command{@value{AS}} to assemble the following statements onto the
3923 end of the data subsection numbered @var{subsection} (which is an
3924 absolute expression). If @var{subsection} is omitted, it defaults
3929 @section @code{.def @var{name}}
3931 @cindex @code{def} directive
3932 @cindex COFF symbols, debugging
3933 @cindex debugging COFF symbols
3934 Begin defining debugging information for a symbol @var{name}; the
3935 definition extends until the @code{.endef} directive is encountered.
3938 This directive is only observed when @command{@value{AS}} is configured for COFF
3939 format output; when producing @code{b.out}, @samp{.def} is recognized,
3946 @section @code{.desc @var{symbol}, @var{abs-expression}}
3948 @cindex @code{desc} directive
3949 @cindex COFF symbol descriptor
3950 @cindex symbol descriptor, COFF
3951 This directive sets the descriptor of the symbol (@pxref{Symbol Attributes})
3952 to the low 16 bits of an absolute expression.
3955 The @samp{.desc} directive is not available when @command{@value{AS}} is
3956 configured for COFF output; it is only for @code{a.out} or @code{b.out}
3957 object format. For the sake of compatibility, @command{@value{AS}} accepts
3958 it, but produces no output, when configured for COFF.
3964 @section @code{.dim}
3966 @cindex @code{dim} directive
3967 @cindex COFF auxiliary symbol information
3968 @cindex auxiliary symbol information, COFF
3969 This directive is generated by compilers to include auxiliary debugging
3970 information in the symbol table. It is only permitted inside
3971 @code{.def}/@code{.endef} pairs.
3974 @samp{.dim} is only meaningful when generating COFF format output; when
3975 @command{@value{AS}} is generating @code{b.out}, it accepts this directive but
3981 @section @code{.double @var{flonums}}
3983 @cindex @code{double} directive
3984 @cindex floating point numbers (double)
3985 @code{.double} expects zero or more flonums, separated by commas. It
3986 assembles floating point numbers.
3988 The exact kind of floating point numbers emitted depends on how
3989 @command{@value{AS}} is configured. @xref{Machine Dependencies}.
3993 On the @value{TARGET} family @samp{.double} emits 64-bit floating-point numbers
3994 in @sc{ieee} format.
3999 @section @code{.eject}
4001 @cindex @code{eject} directive
4002 @cindex new page, in listings
4003 @cindex page, in listings
4004 @cindex listing control: new page
4005 Force a page break at this point, when generating assembly listings.
4008 @section @code{.else}
4010 @cindex @code{else} directive
4011 @code{.else} is part of the @command{@value{AS}} support for conditional
4012 assembly; @pxref{If,,@code{.if}}. It marks the beginning of a section
4013 of code to be assembled if the condition for the preceding @code{.if}
4017 @section @code{.elseif}
4019 @cindex @code{elseif} directive
4020 @code{.elseif} is part of the @command{@value{AS}} support for conditional
4021 assembly; @pxref{If,,@code{.if}}. It is shorthand for beginning a new
4022 @code{.if} block that would otherwise fill the entire @code{.else} section.
4025 @section @code{.end}
4027 @cindex @code{end} directive
4028 @code{.end} marks the end of the assembly file. @command{@value{AS}} does not
4029 process anything in the file past the @code{.end} directive.
4033 @section @code{.endef}
4035 @cindex @code{endef} directive
4036 This directive flags the end of a symbol definition begun with
4040 @samp{.endef} is only meaningful when generating COFF format output; if
4041 @command{@value{AS}} is configured to generate @code{b.out}, it accepts this
4042 directive but ignores it.
4047 @section @code{.endfunc}
4048 @cindex @code{endfunc} directive
4049 @code{.endfunc} marks the end of a function specified with @code{.func}.
4052 @section @code{.endif}
4054 @cindex @code{endif} directive
4055 @code{.endif} is part of the @command{@value{AS}} support for conditional assembly;
4056 it marks the end of a block of code that is only assembled
4057 conditionally. @xref{If,,@code{.if}}.
4060 @section @code{.equ @var{symbol}, @var{expression}}
4062 @cindex @code{equ} directive
4063 @cindex assigning values to symbols
4064 @cindex symbols, assigning values to
4065 This directive sets the value of @var{symbol} to @var{expression}.
4066 It is synonymous with @samp{.set}; @pxref{Set,,@code{.set}}.
4069 The syntax for @code{equ} on the HPPA is
4070 @samp{@var{symbol} .equ @var{expression}}.
4074 @section @code{.equiv @var{symbol}, @var{expression}}
4075 @cindex @code{equiv} directive
4076 The @code{.equiv} directive is like @code{.equ} and @code{.set}, except that
4077 the assembler will signal an error if @var{symbol} is already defined. Note a
4078 symbol which has been referenced but not actually defined is considered to be
4081 Except for the contents of the error message, this is roughly equivalent to
4090 @section @code{.err}
4091 @cindex @code{err} directive
4092 If @command{@value{AS}} assembles a @code{.err} directive, it will print an error
4093 message and, unless the @option{-Z} option was used, it will not generate an
4094 object file. This can be used to signal error an conditionally compiled code.
4097 @section @code{.exitm}
4098 Exit early from the current macro definition. @xref{Macro}.
4101 @section @code{.extern}
4103 @cindex @code{extern} directive
4104 @code{.extern} is accepted in the source program---for compatibility
4105 with other assemblers---but it is ignored. @command{@value{AS}} treats
4106 all undefined symbols as external.
4109 @section @code{.fail @var{expression}}
4111 @cindex @code{fail} directive
4112 Generates an error or a warning. If the value of the @var{expression} is 500
4113 or more, @command{@value{AS}} will print a warning message. If the value is less
4114 than 500, @command{@value{AS}} will print an error message. The message will
4115 include the value of @var{expression}. This can occasionally be useful inside
4116 complex nested macros or conditional assembly.
4118 @ifclear no-file-dir
4120 @section @code{.file @var{string}}
4122 @cindex @code{file} directive
4123 @cindex logical file name
4124 @cindex file name, logical
4125 @code{.file} tells @command{@value{AS}} that we are about to start a new logical
4126 file. @var{string} is the new file name. In general, the filename is
4127 recognized whether or not it is surrounded by quotes @samp{"}; but if you wish
4128 to specify an empty file name, you must give the quotes--@code{""}. This
4129 statement may go away in future: it is only recognized to be compatible with
4130 old @command{@value{AS}} programs.
4132 In some configurations of @command{@value{AS}}, @code{.file} has already been
4133 removed to avoid conflicts with other assemblers. @xref{Machine Dependencies}.
4138 @section @code{.fill @var{repeat} , @var{size} , @var{value}}
4140 @cindex @code{fill} directive
4141 @cindex writing patterns in memory
4142 @cindex patterns, writing in memory
4143 @var{repeat}, @var{size} and @var{value} are absolute expressions.
4144 This emits @var{repeat} copies of @var{size} bytes. @var{Repeat}
4145 may be zero or more. @var{Size} may be zero or more, but if it is
4146 more than 8, then it is deemed to have the value 8, compatible with
4147 other people's assemblers. The contents of each @var{repeat} bytes
4148 is taken from an 8-byte number. The highest order 4 bytes are
4149 zero. The lowest order 4 bytes are @var{value} rendered in the
4150 byte-order of an integer on the computer @command{@value{AS}} is assembling for.
4151 Each @var{size} bytes in a repetition is taken from the lowest order
4152 @var{size} bytes of this number. Again, this bizarre behavior is
4153 compatible with other people's assemblers.
4155 @var{size} and @var{value} are optional.
4156 If the second comma and @var{value} are absent, @var{value} is
4157 assumed zero. If the first comma and following tokens are absent,
4158 @var{size} is assumed to be 1.
4161 @section @code{.float @var{flonums}}
4163 @cindex floating point numbers (single)
4164 @cindex @code{float} directive
4165 This directive assembles zero or more flonums, separated by commas. It
4166 has the same effect as @code{.single}.
4168 The exact kind of floating point numbers emitted depends on how
4169 @command{@value{AS}} is configured.
4170 @xref{Machine Dependencies}.
4174 On the @value{TARGET} family, @code{.float} emits 32-bit floating point numbers
4175 in @sc{ieee} format.
4180 @section @code{.func @var{name}[,@var{label}]}
4181 @cindex @code{func} directive
4182 @code{.func} emits debugging information to denote function @var{name}, and
4183 is ignored unless the file is assembled with debugging enabled.
4184 Only @samp{--gstabs} is currently supported.
4185 @var{label} is the entry point of the function and if omitted @var{name}
4186 prepended with the @samp{leading char} is used.
4187 @samp{leading char} is usually @code{_} or nothing, depending on the target.
4188 All functions are currently defined to have @code{void} return type.
4189 The function must be terminated with @code{.endfunc}.
4192 @section @code{.global @var{symbol}}, @code{.globl @var{symbol}}
4194 @cindex @code{global} directive
4195 @cindex symbol, making visible to linker
4196 @code{.global} makes the symbol visible to @code{@value{LD}}. If you define
4197 @var{symbol} in your partial program, its value is made available to
4198 other partial programs that are linked with it. Otherwise,
4199 @var{symbol} takes its attributes from a symbol of the same name
4200 from another file linked into the same program.
4202 Both spellings (@samp{.globl} and @samp{.global}) are accepted, for
4203 compatibility with other assemblers.
4206 On the HPPA, @code{.global} is not always enough to make it accessible to other
4207 partial programs. You may need the HPPA-only @code{.EXPORT} directive as well.
4208 @xref{HPPA Directives,, HPPA Assembler Directives}.
4213 @section @code{.hidden @var{names}}
4215 @cindex @code{.hidden} directive
4217 This one of the ELF visibility directives. The other two are
4218 @code{.internal} (@pxref{Internal,,@code{.internal}}) and
4219 @code{.protected} (@pxref{Protected,,@code{.protected}}).
4221 This directive overrides the named symbols default visibility (which is set by
4222 their binding: local, global or weak). The directive sets the visibility to
4223 @code{hidden} which means that the symbols are not visible to other components.
4224 Such symbols are always considered to be @code{protected} as well.
4228 @section @code{.hword @var{expressions}}
4230 @cindex @code{hword} directive
4231 @cindex integers, 16-bit
4232 @cindex numbers, 16-bit
4233 @cindex sixteen bit integers
4234 This expects zero or more @var{expressions}, and emits
4235 a 16 bit number for each.
4238 This directive is a synonym for @samp{.short}; depending on the target
4239 architecture, it may also be a synonym for @samp{.word}.
4243 This directive is a synonym for @samp{.short}.
4246 This directive is a synonym for both @samp{.short} and @samp{.word}.
4251 @section @code{.ident}
4253 @cindex @code{ident} directive
4254 This directive is used by some assemblers to place tags in object files.
4255 @command{@value{AS}} simply accepts the directive for source-file
4256 compatibility with such assemblers, but does not actually emit anything
4260 @section @code{.if @var{absolute expression}}
4262 @cindex conditional assembly
4263 @cindex @code{if} directive
4264 @code{.if} marks the beginning of a section of code which is only
4265 considered part of the source program being assembled if the argument
4266 (which must be an @var{absolute expression}) is non-zero. The end of
4267 the conditional section of code must be marked by @code{.endif}
4268 (@pxref{Endif,,@code{.endif}}); optionally, you may include code for the
4269 alternative condition, flagged by @code{.else} (@pxref{Else,,@code{.else}}).
4270 If you have several conditions to check, @code{.elseif} may be used to avoid
4271 nesting blocks if/else within each subsequent @code{.else} block.
4273 The following variants of @code{.if} are also supported:
4275 @cindex @code{ifdef} directive
4276 @item .ifdef @var{symbol}
4277 Assembles the following section of code if the specified @var{symbol}
4278 has been defined. Note a symbol which has been referenced but not yet defined
4279 is considered to be undefined.
4281 @cindex @code{ifc} directive
4282 @item .ifc @var{string1},@var{string2}
4283 Assembles the following section of code if the two strings are the same. The
4284 strings may be optionally quoted with single quotes. If they are not quoted,
4285 the first string stops at the first comma, and the second string stops at the
4286 end of the line. Strings which contain whitespace should be quoted. The
4287 string comparison is case sensitive.
4289 @cindex @code{ifeq} directive
4290 @item .ifeq @var{absolute expression}
4291 Assembles the following section of code if the argument is zero.
4293 @cindex @code{ifeqs} directive
4294 @item .ifeqs @var{string1},@var{string2}
4295 Another form of @code{.ifc}. The strings must be quoted using double quotes.
4297 @cindex @code{ifge} directive
4298 @item .ifge @var{absolute expression}
4299 Assembles the following section of code if the argument is greater than or
4302 @cindex @code{ifgt} directive
4303 @item .ifgt @var{absolute expression}
4304 Assembles the following section of code if the argument is greater than zero.
4306 @cindex @code{ifle} directive
4307 @item .ifle @var{absolute expression}
4308 Assembles the following section of code if the argument is less than or equal
4311 @cindex @code{iflt} directive
4312 @item .iflt @var{absolute expression}
4313 Assembles the following section of code if the argument is less than zero.
4315 @cindex @code{ifnc} directive
4316 @item .ifnc @var{string1},@var{string2}.
4317 Like @code{.ifc}, but the sense of the test is reversed: this assembles the
4318 following section of code if the two strings are not the same.
4320 @cindex @code{ifndef} directive
4321 @cindex @code{ifnotdef} directive
4322 @item .ifndef @var{symbol}
4323 @itemx .ifnotdef @var{symbol}
4324 Assembles the following section of code if the specified @var{symbol}
4325 has not been defined. Both spelling variants are equivalent. Note a symbol
4326 which has been referenced but not yet defined is considered to be undefined.
4328 @cindex @code{ifne} directive
4329 @item .ifne @var{absolute expression}
4330 Assembles the following section of code if the argument is not equal to zero
4331 (in other words, this is equivalent to @code{.if}).
4333 @cindex @code{ifnes} directive
4334 @item .ifnes @var{string1},@var{string2}
4335 Like @code{.ifeqs}, but the sense of the test is reversed: this assembles the
4336 following section of code if the two strings are not the same.
4340 @section @code{.incbin "@var{file}"[,@var{skip}[,@var{count}]]}
4342 @cindex @code{incbin} directive
4343 @cindex binary files, including
4344 The @code{incbin} directive includes @var{file} verbatim at the current
4345 location. You can control the search paths used with the @samp{-I} command-line
4346 option (@pxref{Invoking,,Command-Line Options}). Quotation marks are required
4349 The @var{skip} argument skips a number of bytes from the start of the
4350 @var{file}. The @var{count} argument indicates the maximum number of bytes to
4351 read. Note that the data is not aligned in any way, so it is the user's
4352 responsibility to make sure that proper alignment is provided both before and
4353 after the @code{incbin} directive.
4356 @section @code{.include "@var{file}"}
4358 @cindex @code{include} directive
4359 @cindex supporting files, including
4360 @cindex files, including
4361 This directive provides a way to include supporting files at specified
4362 points in your source program. The code from @var{file} is assembled as
4363 if it followed the point of the @code{.include}; when the end of the
4364 included file is reached, assembly of the original file continues. You
4365 can control the search paths used with the @samp{-I} command-line option
4366 (@pxref{Invoking,,Command-Line Options}). Quotation marks are required
4370 @section @code{.int @var{expressions}}
4372 @cindex @code{int} directive
4373 @cindex integers, 32-bit
4374 Expect zero or more @var{expressions}, of any section, separated by commas.
4375 For each expression, emit a number that, at run time, is the value of that
4376 expression. The byte order and bit size of the number depends on what kind
4377 of target the assembly is for.
4381 On the H8/500 and most forms of the H8/300, @code{.int} emits 16-bit
4382 integers. On the H8/300H and the Hitachi SH, however, @code{.int} emits
4389 @section @code{.internal @var{names}}
4391 @cindex @code{.internal} directive
4393 This one of the ELF visibility directives. The other two are
4394 @code{.hidden} (@pxref{Hidden,,@code{.hidden}}) and
4395 @code{.protected} (@pxref{Protected,,@code{.protected}}).
4397 This directive overrides the named symbols default visibility (which is set by
4398 their binding: local, global or weak). The directive sets the visibility to
4399 @code{internal} which means that the symbols are considered to be @code{hidden}
4400 (ie not visible to other components), and that some extra, processor specific
4401 processing must also be performed upon the symbols as well.
4405 @section @code{.irp @var{symbol},@var{values}}@dots{}
4407 @cindex @code{irp} directive
4408 Evaluate a sequence of statements assigning different values to @var{symbol}.
4409 The sequence of statements starts at the @code{.irp} directive, and is
4410 terminated by an @code{.endr} directive. For each @var{value}, @var{symbol} is
4411 set to @var{value}, and the sequence of statements is assembled. If no
4412 @var{value} is listed, the sequence of statements is assembled once, with
4413 @var{symbol} set to the null string. To refer to @var{symbol} within the
4414 sequence of statements, use @var{\symbol}.
4416 For example, assembling
4424 is equivalent to assembling
4433 @section @code{.irpc @var{symbol},@var{values}}@dots{}
4435 @cindex @code{irpc} directive
4436 Evaluate a sequence of statements assigning different values to @var{symbol}.
4437 The sequence of statements starts at the @code{.irpc} directive, and is
4438 terminated by an @code{.endr} directive. For each character in @var{value},
4439 @var{symbol} is set to the character, and the sequence of statements is
4440 assembled. If no @var{value} is listed, the sequence of statements is
4441 assembled once, with @var{symbol} set to the null string. To refer to
4442 @var{symbol} within the sequence of statements, use @var{\symbol}.
4444 For example, assembling
4452 is equivalent to assembling
4461 @section @code{.lcomm @var{symbol} , @var{length}}
4463 @cindex @code{lcomm} directive
4464 @cindex local common symbols
4465 @cindex symbols, local common
4466 Reserve @var{length} (an absolute expression) bytes for a local common
4467 denoted by @var{symbol}. The section and value of @var{symbol} are
4468 those of the new local common. The addresses are allocated in the bss
4469 section, so that at run-time the bytes start off zeroed. @var{Symbol}
4470 is not declared global (@pxref{Global,,@code{.global}}), so is normally
4471 not visible to @code{@value{LD}}.
4474 Some targets permit a third argument to be used with @code{.lcomm}. This
4475 argument specifies the desired alignment of the symbol in the bss section.
4479 The syntax for @code{.lcomm} differs slightly on the HPPA. The syntax is
4480 @samp{@var{symbol} .lcomm, @var{length}}; @var{symbol} is optional.
4484 @section @code{.lflags}
4486 @cindex @code{lflags} directive (ignored)
4487 @command{@value{AS}} accepts this directive, for compatibility with other
4488 assemblers, but ignores it.
4490 @ifclear no-line-dir
4492 @section @code{.line @var{line-number}}
4494 @cindex @code{line} directive
4498 @section @code{.ln @var{line-number}}
4500 @cindex @code{ln} directive
4502 @cindex logical line number
4504 Change the logical line number. @var{line-number} must be an absolute
4505 expression. The next line has that logical line number. Therefore any other
4506 statements on the current line (after a statement separator character) are
4507 reported as on logical line number @var{line-number} @minus{} 1. One day
4508 @command{@value{AS}} will no longer support this directive: it is recognized only
4509 for compatibility with existing assembler programs.
4513 @emph{Warning:} In the AMD29K configuration of @value{AS}, this command is
4514 not available; use the synonym @code{.ln} in that context.
4519 @ifclear no-line-dir
4520 Even though this is a directive associated with the @code{a.out} or
4521 @code{b.out} object-code formats, @command{@value{AS}} still recognizes it
4522 when producing COFF output, and treats @samp{.line} as though it
4523 were the COFF @samp{.ln} @emph{if} it is found outside a
4524 @code{.def}/@code{.endef} pair.
4526 Inside a @code{.def}, @samp{.line} is, instead, one of the directives
4527 used by compilers to generate auxiliary symbol information for
4532 @section @code{.linkonce [@var{type}]}
4534 @cindex @code{linkonce} directive
4535 @cindex common sections
4536 Mark the current section so that the linker only includes a single copy of it.
4537 This may be used to include the same section in several different object files,
4538 but ensure that the linker will only include it once in the final output file.
4539 The @code{.linkonce} pseudo-op must be used for each instance of the section.
4540 Duplicate sections are detected based on the section name, so it should be
4543 This directive is only supported by a few object file formats; as of this
4544 writing, the only object file format which supports it is the Portable
4545 Executable format used on Windows NT.
4547 The @var{type} argument is optional. If specified, it must be one of the
4548 following strings. For example:
4552 Not all types may be supported on all object file formats.
4556 Silently discard duplicate sections. This is the default.
4559 Warn if there are duplicate sections, but still keep only one copy.
4562 Warn if any of the duplicates have different sizes.
4565 Warn if any of the duplicates do not have exactly the same contents.
4569 @section @code{.ln @var{line-number}}
4571 @cindex @code{ln} directive
4572 @ifclear no-line-dir
4573 @samp{.ln} is a synonym for @samp{.line}.
4576 Tell @command{@value{AS}} to change the logical line number. @var{line-number}
4577 must be an absolute expression. The next line has that logical
4578 line number, so any other statements on the current line (after a
4579 statement separator character @code{;}) are reported as on logical
4580 line number @var{line-number} @minus{} 1.
4583 This directive is accepted, but ignored, when @command{@value{AS}} is
4584 configured for @code{b.out}; its effect is only associated with COFF
4590 @section @code{.mri @var{val}}
4592 @cindex @code{mri} directive
4593 @cindex MRI mode, temporarily
4594 If @var{val} is non-zero, this tells @command{@value{AS}} to enter MRI mode. If
4595 @var{val} is zero, this tells @command{@value{AS}} to exit MRI mode. This change
4596 affects code assembled until the next @code{.mri} directive, or until the end
4597 of the file. @xref{M, MRI mode, MRI mode}.
4600 @section @code{.list}
4602 @cindex @code{list} directive
4603 @cindex listing control, turning on
4604 Control (in conjunction with the @code{.nolist} directive) whether or
4605 not assembly listings are generated. These two directives maintain an
4606 internal counter (which is zero initially). @code{.list} increments the
4607 counter, and @code{.nolist} decrements it. Assembly listings are
4608 generated whenever the counter is greater than zero.
4610 By default, listings are disabled. When you enable them (with the
4611 @samp{-a} command line option; @pxref{Invoking,,Command-Line Options}),
4612 the initial value of the listing counter is one.
4615 @section @code{.long @var{expressions}}
4617 @cindex @code{long} directive
4618 @code{.long} is the same as @samp{.int}, @pxref{Int,,@code{.int}}.
4621 @c no one seems to know what this is for or whether this description is
4622 @c what it really ought to do
4624 @section @code{.lsym @var{symbol}, @var{expression}}
4626 @cindex @code{lsym} directive
4627 @cindex symbol, not referenced in assembly
4628 @code{.lsym} creates a new symbol named @var{symbol}, but does not put it in
4629 the hash table, ensuring it cannot be referenced by name during the
4630 rest of the assembly. This sets the attributes of the symbol to be
4631 the same as the expression value:
4633 @var{other} = @var{descriptor} = 0
4634 @var{type} = @r{(section of @var{expression})}
4635 @var{value} = @var{expression}
4638 The new symbol is not flagged as external.
4642 @section @code{.macro}
4645 The commands @code{.macro} and @code{.endm} allow you to define macros that
4646 generate assembly output. For example, this definition specifies a macro
4647 @code{sum} that puts a sequence of numbers into memory:
4650 .macro sum from=0, to=5
4659 With that definition, @samp{SUM 0,5} is equivalent to this assembly input:
4671 @item .macro @var{macname}
4672 @itemx .macro @var{macname} @var{macargs} @dots{}
4673 @cindex @code{macro} directive
4674 Begin the definition of a macro called @var{macname}. If your macro
4675 definition requires arguments, specify their names after the macro name,
4676 separated by commas or spaces. You can supply a default value for any
4677 macro argument by following the name with @samp{=@var{deflt}}. For
4678 example, these are all valid @code{.macro} statements:
4682 Begin the definition of a macro called @code{comm}, which takes no
4685 @item .macro plus1 p, p1
4686 @itemx .macro plus1 p p1
4687 Either statement begins the definition of a macro called @code{plus1},
4688 which takes two arguments; within the macro definition, write
4689 @samp{\p} or @samp{\p1} to evaluate the arguments.
4691 @item .macro reserve_str p1=0 p2
4692 Begin the definition of a macro called @code{reserve_str}, with two
4693 arguments. The first argument has a default value, but not the second.
4694 After the definition is complete, you can call the macro either as
4695 @samp{reserve_str @var{a},@var{b}} (with @samp{\p1} evaluating to
4696 @var{a} and @samp{\p2} evaluating to @var{b}), or as @samp{reserve_str
4697 ,@var{b}} (with @samp{\p1} evaluating as the default, in this case
4698 @samp{0}, and @samp{\p2} evaluating to @var{b}).
4701 When you call a macro, you can specify the argument values either by
4702 position, or by keyword. For example, @samp{sum 9,17} is equivalent to
4703 @samp{sum to=17, from=9}.
4706 @cindex @code{endm} directive
4707 Mark the end of a macro definition.
4710 @cindex @code{exitm} directive
4711 Exit early from the current macro definition.
4713 @cindex number of macros executed
4714 @cindex macros, count executed
4716 @command{@value{AS}} maintains a counter of how many macros it has
4717 executed in this pseudo-variable; you can copy that number to your
4718 output with @samp{\@@}, but @emph{only within a macro definition}.
4721 @item LOCAL @var{name} [ , @dots{} ]
4722 @emph{Warning: @code{LOCAL} is only available if you select ``alternate
4723 macro syntax'' with @samp{-a} or @samp{--alternate}.} @xref{Alternate,,
4724 Alternate macro syntax}.
4726 Generate a string replacement for each of the @var{name} arguments, and
4727 replace any instances of @var{name} in each macro expansion. The
4728 replacement string is unique in the assembly, and different for each
4729 separate macro expansion. @code{LOCAL} allows you to write macros that
4730 define symbols, without fear of conflict between separate macro expansions.
4735 @section @code{.nolist}
4737 @cindex @code{nolist} directive
4738 @cindex listing control, turning off
4739 Control (in conjunction with the @code{.list} directive) whether or
4740 not assembly listings are generated. These two directives maintain an
4741 internal counter (which is zero initially). @code{.list} increments the
4742 counter, and @code{.nolist} decrements it. Assembly listings are
4743 generated whenever the counter is greater than zero.
4746 @section @code{.octa @var{bignums}}
4748 @c FIXME: double size emitted for "octa" on i960, others? Or warn?
4749 @cindex @code{octa} directive
4750 @cindex integer, 16-byte
4751 @cindex sixteen byte integer
4752 This directive expects zero or more bignums, separated by commas. For each
4753 bignum, it emits a 16-byte integer.
4755 The term ``octa'' comes from contexts in which a ``word'' is two bytes;
4756 hence @emph{octa}-word for 16 bytes.
4759 @section @code{.org @var{new-lc} , @var{fill}}
4761 @cindex @code{org} directive
4762 @cindex location counter, advancing
4763 @cindex advancing location counter
4764 @cindex current address, advancing
4765 Advance the location counter of the current section to
4766 @var{new-lc}. @var{new-lc} is either an absolute expression or an
4767 expression with the same section as the current subsection. That is,
4768 you can't use @code{.org} to cross sections: if @var{new-lc} has the
4769 wrong section, the @code{.org} directive is ignored. To be compatible
4770 with former assemblers, if the section of @var{new-lc} is absolute,
4771 @command{@value{AS}} issues a warning, then pretends the section of @var{new-lc}
4772 is the same as the current subsection.
4774 @code{.org} may only increase the location counter, or leave it
4775 unchanged; you cannot use @code{.org} to move the location counter
4778 @c double negative used below "not undefined" because this is a specific
4779 @c reference to "undefined" (as SEG_UNKNOWN is called in this manual)
4780 @c section. doc@cygnus.com 18feb91
4781 Because @command{@value{AS}} tries to assemble programs in one pass, @var{new-lc}
4782 may not be undefined. If you really detest this restriction we eagerly await
4783 a chance to share your improved assembler.
4785 Beware that the origin is relative to the start of the section, not
4786 to the start of the subsection. This is compatible with other
4787 people's assemblers.
4789 When the location counter (of the current subsection) is advanced, the
4790 intervening bytes are filled with @var{fill} which should be an
4791 absolute expression. If the comma and @var{fill} are omitted,
4792 @var{fill} defaults to zero.
4795 @section @code{.p2align[wl] @var{abs-expr}, @var{abs-expr}, @var{abs-expr}}
4797 @cindex padding the location counter given a power of two
4798 @cindex @code{p2align} directive
4799 Pad the location counter (in the current subsection) to a particular
4800 storage boundary. The first expression (which must be absolute) is the
4801 number of low-order zero bits the location counter must have after
4802 advancement. For example @samp{.p2align 3} advances the location
4803 counter until it a multiple of 8. If the location counter is already a
4804 multiple of 8, no change is needed.
4806 The second expression (also absolute) gives the fill value to be stored in the
4807 padding bytes. It (and the comma) may be omitted. If it is omitted, the
4808 padding bytes are normally zero. However, on some systems, if the section is
4809 marked as containing code and the fill value is omitted, the space is filled
4810 with no-op instructions.
4812 The third expression is also absolute, and is also optional. If it is present,
4813 it is the maximum number of bytes that should be skipped by this alignment
4814 directive. If doing the alignment would require skipping more bytes than the
4815 specified maximum, then the alignment is not done at all. You can omit the
4816 fill value (the second argument) entirely by simply using two commas after the
4817 required alignment; this can be useful if you want the alignment to be filled
4818 with no-op instructions when appropriate.
4820 @cindex @code{p2alignw} directive
4821 @cindex @code{p2alignl} directive
4822 The @code{.p2alignw} and @code{.p2alignl} directives are variants of the
4823 @code{.p2align} directive. The @code{.p2alignw} directive treats the fill
4824 pattern as a two byte word value. The @code{.p2alignl} directives treats the
4825 fill pattern as a four byte longword value. For example, @code{.p2alignw
4826 2,0x368d} will align to a multiple of 4. If it skips two bytes, they will be
4827 filled in with the value 0x368d (the exact placement of the bytes depends upon
4828 the endianness of the processor). If it skips 1 or 3 bytes, the fill value is
4833 @section @code{.previous}
4835 @cindex @code{.previous} directive
4836 @cindex Section Stack
4837 This is one of the ELF section stack manipulation directives. The others are
4838 @code{.section} (@pxref{Section}), @code{.subsection} (@pxref{SubSection}),
4839 @code{.pushsection} (@pxref{PushSection}), and @code{.popsection}
4840 (@pxref{PopSection}).
4842 This directive swaps the current section (and subsection) with most recently
4843 referenced section (and subsection) prior to this one. Multiple
4844 @code{.previous} directives in a row will flip between two sections (and their
4847 In terms of the section stack, this directive swaps the current section with
4848 the top section on the section stack.
4853 @section @code{.popsection}
4855 @cindex @code{.popsection} directive
4856 @cindex Section Stack
4857 This is one of the ELF section stack manipulation directives. The others are
4858 @code{.section} (@pxref{Section}), @code{.subsection} (@pxref{SubSection}),
4859 @code{.pushsection} (@pxref{PushSection}), and @code{.previous}
4862 This directive replaces the current section (and subsection) with the top
4863 section (and subsection) on the section stack. This section is popped off the
4868 @section @code{.print @var{string}}
4870 @cindex @code{print} directive
4871 @command{@value{AS}} will print @var{string} on the standard output during
4872 assembly. You must put @var{string} in double quotes.
4876 @section @code{.protected @var{names}}
4878 @cindex @code{.protected} directive
4880 This one of the ELF visibility directives. The other two are
4881 @code{.hidden} (@pxref{Hidden}) and @code{.internal} (@pxref{Internal}).
4883 This directive overrides the named symbols default visibility (which is set by
4884 their binding: local, global or weak). The directive sets the visibility to
4885 @code{protected} which means that any references to the symbols from within the
4886 components that defines them must be resolved to the definition in that
4887 component, even if a definition in another component would normally preempt
4892 @section @code{.psize @var{lines} , @var{columns}}
4894 @cindex @code{psize} directive
4895 @cindex listing control: paper size
4896 @cindex paper size, for listings
4897 Use this directive to declare the number of lines---and, optionally, the
4898 number of columns---to use for each page, when generating listings.
4900 If you do not use @code{.psize}, listings use a default line-count
4901 of 60. You may omit the comma and @var{columns} specification; the
4902 default width is 200 columns.
4904 @command{@value{AS}} generates formfeeds whenever the specified number of
4905 lines is exceeded (or whenever you explicitly request one, using
4908 If you specify @var{lines} as @code{0}, no formfeeds are generated save
4909 those explicitly specified with @code{.eject}.
4912 @section @code{.purgem @var{name}}
4914 @cindex @code{purgem} directive
4915 Undefine the macro @var{name}, so that later uses of the string will not be
4916 expanded. @xref{Macro}.
4920 @section @code{.pushsection @var{name} , @var{subsection}}
4922 @cindex @code{.pushsection} directive
4923 @cindex Section Stack
4924 This is one of the ELF section stack manipulation directives. The others are
4925 @code{.section} (@pxref{Section}), @code{.subsection} (@pxref{SubSection}),
4926 @code{.popsection} (@pxref{PopSection}), and @code{.previous}
4929 This directive is a synonym for @code{.section}. It pushes the current section
4930 (and subsection) onto the top of the section stack, and then replaces the
4931 current section and subsection with @code{name} and @code{subsection}.
4935 @section @code{.quad @var{bignums}}
4937 @cindex @code{quad} directive
4938 @code{.quad} expects zero or more bignums, separated by commas. For
4939 each bignum, it emits
4941 an 8-byte integer. If the bignum won't fit in 8 bytes, it prints a
4942 warning message; and just takes the lowest order 8 bytes of the bignum.
4943 @cindex eight-byte integer
4944 @cindex integer, 8-byte
4946 The term ``quad'' comes from contexts in which a ``word'' is two bytes;
4947 hence @emph{quad}-word for 8 bytes.
4950 a 16-byte integer. If the bignum won't fit in 16 bytes, it prints a
4951 warning message; and just takes the lowest order 16 bytes of the bignum.
4952 @cindex sixteen-byte integer
4953 @cindex integer, 16-byte
4957 @section @code{.rept @var{count}}
4959 @cindex @code{rept} directive
4960 Repeat the sequence of lines between the @code{.rept} directive and the next
4961 @code{.endr} directive @var{count} times.
4963 For example, assembling
4971 is equivalent to assembling
4980 @section @code{.sbttl "@var{subheading}"}
4982 @cindex @code{sbttl} directive
4983 @cindex subtitles for listings
4984 @cindex listing control: subtitle
4985 Use @var{subheading} as the title (third line, immediately after the
4986 title line) when generating assembly listings.
4988 This directive affects subsequent pages, as well as the current page if
4989 it appears within ten lines of the top of a page.
4993 @section @code{.scl @var{class}}
4995 @cindex @code{scl} directive
4996 @cindex symbol storage class (COFF)
4997 @cindex COFF symbol storage class
4998 Set the storage-class value for a symbol. This directive may only be
4999 used inside a @code{.def}/@code{.endef} pair. Storage class may flag
5000 whether a symbol is static or external, or it may record further
5001 symbolic debugging information.
5004 The @samp{.scl} directive is primarily associated with COFF output; when
5005 configured to generate @code{b.out} output format, @command{@value{AS}}
5006 accepts this directive but ignores it.
5011 @section @code{.section @var{name}} (COFF version)
5013 @cindex @code{section} directive
5014 @cindex named section
5015 Use the @code{.section} directive to assemble the following code into a section
5018 This directive is only supported for targets that actually support arbitrarily
5019 named sections; on @code{a.out} targets, for example, it is not accepted, even
5020 with a standard @code{a.out} section name.
5022 For COFF targets, the @code{.section} directive is used in one of the following
5026 .section @var{name}[, "@var{flags}"]
5027 .section @var{name}[, @var{subsegment}]
5030 If the optional argument is quoted, it is taken as flags to use for the
5031 section. Each flag is a single character. The following flags are recognized:
5034 bss section (uninitialized data)
5036 section is not loaded
5046 shared section (meaningful for PE targets)
5048 ignored. (For compatibility with the ELF version)
5051 If no flags are specified, the default flags depend upon the section name. If
5052 the section name is not recognized, the default will be for the section to be
5053 loaded and writable. Note the @code{n} and @code{w} flags remove attributes
5054 from the section, rather than adding them, so if they are used on their own it
5055 will be as if no flags had been specified at all.
5057 If the optional argument to the @code{.section} directive is not quoted, it is
5058 taken as a subsegment number (@pxref{Sub-Sections}).
5061 @section @code{.section @var{name}} (ELF version)
5063 @cindex @code{section} directive
5064 @cindex named section
5066 @cindex Section Stack
5067 This is one of the ELF section stack manipulation directives. The others are
5068 @code{.subsection} (@pxref{SubSection}), @code{.pushsection}
5069 (@pxref{PushSection}), @code{.popsection} (@pxref{PopSection}), and
5070 @code{.previous} (@pxref{Previous}).
5073 For ELF targets, the @code{.section} directive is used like this:
5076 .section @var{name} [, "@var{flags}"[, @@@var{type}[, @@@var{entsize}]]]
5079 The optional @var{flags} argument is a quoted string which may contain any
5080 combination of the following characters:
5083 section is allocatable
5087 section is executable
5089 section is mergeable
5091 section contains zero terminated strings
5094 The optional @var{type} argument may contain one of the following constants:
5097 section contains data
5099 section does not contain data (i.e., section only occupies space)
5102 If @var{flags} contains @code{M} flag, @var{type} argument must be specified
5103 as well as @var{entsize} argument. Sections with @code{M} flag but not
5104 @code{S} flag must contain fixed size constants, each @var{entsize} octets
5105 long. Sections with both @code{M} and @code{S} must contain zero terminated
5106 strings where each character is @var{entsize} bytes long. The linker may remove
5107 duplicates within sections with the same name, same entity size and same flags.
5109 If no flags are specified, the default flags depend upon the section name. If
5110 the section name is not recognized, the default will be for the section to have
5111 none of the above flags: it will not be allocated in memory, nor writable, nor
5112 executable. The section will contain data.
5114 For ELF targets, the assembler supports another type of @code{.section}
5115 directive for compatibility with the Solaris assembler:
5118 .section "@var{name}"[, @var{flags}...]
5121 Note that the section name is quoted. There may be a sequence of comma
5125 section is allocatable
5129 section is executable
5132 This directive replaces the current section and subsection. The replaced
5133 section and subsection are pushed onto the section stack. See the contents of
5134 the gas testsuite directory @code{gas/testsuite/gas/elf} for some examples of
5135 how this directive and the other section stack directives work.
5138 @section @code{.set @var{symbol}, @var{expression}}
5140 @cindex @code{set} directive
5141 @cindex symbol value, setting
5142 Set the value of @var{symbol} to @var{expression}. This
5143 changes @var{symbol}'s value and type to conform to
5144 @var{expression}. If @var{symbol} was flagged as external, it remains
5145 flagged (@pxref{Symbol Attributes}).
5147 You may @code{.set} a symbol many times in the same assembly.
5149 If you @code{.set} a global symbol, the value stored in the object
5150 file is the last value stored into it.
5153 The syntax for @code{set} on the HPPA is
5154 @samp{@var{symbol} .set @var{expression}}.
5158 @section @code{.short @var{expressions}}
5160 @cindex @code{short} directive
5162 @code{.short} is normally the same as @samp{.word}.
5163 @xref{Word,,@code{.word}}.
5165 In some configurations, however, @code{.short} and @code{.word} generate
5166 numbers of different lengths; @pxref{Machine Dependencies}.
5170 @code{.short} is the same as @samp{.word}. @xref{Word,,@code{.word}}.
5173 This expects zero or more @var{expressions}, and emits
5174 a 16 bit number for each.
5179 @section @code{.single @var{flonums}}
5181 @cindex @code{single} directive
5182 @cindex floating point numbers (single)
5183 This directive assembles zero or more flonums, separated by commas. It
5184 has the same effect as @code{.float}.
5186 The exact kind of floating point numbers emitted depends on how
5187 @command{@value{AS}} is configured. @xref{Machine Dependencies}.
5191 On the @value{TARGET} family, @code{.single} emits 32-bit floating point
5192 numbers in @sc{ieee} format.
5197 @section @code{.size} (COFF version)
5199 @cindex @code{size} directive
5200 This directive is generated by compilers to include auxiliary debugging
5201 information in the symbol table. It is only permitted inside
5202 @code{.def}/@code{.endef} pairs.
5205 @samp{.size} is only meaningful when generating COFF format output; when
5206 @command{@value{AS}} is generating @code{b.out}, it accepts this directive but
5210 @section @code{.size @var{name} , @var{expression}} (ELF version)
5211 @cindex @code{size} directive
5213 This directive is used to set the size associated with a symbol @var{name}.
5214 The size in bytes is computed from @var{expression} which can make use of label
5215 arithmetic. This directive is typically used to set the size of function
5219 @section @code{.sleb128 @var{expressions}}
5221 @cindex @code{sleb128} directive
5222 @var{sleb128} stands for ``signed little endian base 128.'' This is a
5223 compact, variable length representation of numbers used by the DWARF
5224 symbolic debugging format. @xref{Uleb128,@code{.uleb128}}.
5226 @ifclear no-space-dir
5228 @section @code{.skip @var{size} , @var{fill}}
5230 @cindex @code{skip} directive
5231 @cindex filling memory
5232 This directive emits @var{size} bytes, each of value @var{fill}. Both
5233 @var{size} and @var{fill} are absolute expressions. If the comma and
5234 @var{fill} are omitted, @var{fill} is assumed to be zero. This is the same as
5238 @section @code{.space @var{size} , @var{fill}}
5240 @cindex @code{space} directive
5241 @cindex filling memory
5242 This directive emits @var{size} bytes, each of value @var{fill}. Both
5243 @var{size} and @var{fill} are absolute expressions. If the comma
5244 and @var{fill} are omitted, @var{fill} is assumed to be zero. This is the same
5249 @emph{Warning:} @code{.space} has a completely different meaning for HPPA
5250 targets; use @code{.block} as a substitute. See @cite{HP9000 Series 800
5251 Assembly Language Reference Manual} (HP 92432-90001) for the meaning of the
5252 @code{.space} directive. @xref{HPPA Directives,,HPPA Assembler Directives},
5261 @section @code{.space}
5262 @cindex @code{space} directive
5264 On the AMD 29K, this directive is ignored; it is accepted for
5265 compatibility with other AMD 29K assemblers.
5268 @emph{Warning:} In most versions of the @sc{gnu} assembler, the directive
5269 @code{.space} has the effect of @code{.block} @xref{Machine Dependencies}.
5275 @section @code{.stabd, .stabn, .stabs}
5277 @cindex symbolic debuggers, information for
5278 @cindex @code{stab@var{x}} directives
5279 There are three directives that begin @samp{.stab}.
5280 All emit symbols (@pxref{Symbols}), for use by symbolic debuggers.
5281 The symbols are not entered in the @command{@value{AS}} hash table: they
5282 cannot be referenced elsewhere in the source file.
5283 Up to five fields are required:
5287 This is the symbol's name. It may contain any character except
5288 @samp{\000}, so is more general than ordinary symbol names. Some
5289 debuggers used to code arbitrarily complex structures into symbol names
5293 An absolute expression. The symbol's type is set to the low 8 bits of
5294 this expression. Any bit pattern is permitted, but @code{@value{LD}}
5295 and debuggers choke on silly bit patterns.
5298 An absolute expression. The symbol's ``other'' attribute is set to the
5299 low 8 bits of this expression.
5302 An absolute expression. The symbol's descriptor is set to the low 16
5303 bits of this expression.
5306 An absolute expression which becomes the symbol's value.
5309 If a warning is detected while reading a @code{.stabd}, @code{.stabn},
5310 or @code{.stabs} statement, the symbol has probably already been created;
5311 you get a half-formed symbol in your object file. This is
5312 compatible with earlier assemblers!
5315 @cindex @code{stabd} directive
5316 @item .stabd @var{type} , @var{other} , @var{desc}
5318 The ``name'' of the symbol generated is not even an empty string.
5319 It is a null pointer, for compatibility. Older assemblers used a
5320 null pointer so they didn't waste space in object files with empty
5323 The symbol's value is set to the location counter,
5324 relocatably. When your program is linked, the value of this symbol
5325 is the address of the location counter when the @code{.stabd} was
5328 @cindex @code{stabn} directive
5329 @item .stabn @var{type} , @var{other} , @var{desc} , @var{value}
5330 The name of the symbol is set to the empty string @code{""}.
5332 @cindex @code{stabs} directive
5333 @item .stabs @var{string} , @var{type} , @var{other} , @var{desc} , @var{value}
5334 All five fields are specified.
5340 @section @code{.string} "@var{str}"
5342 @cindex string, copying to object file
5343 @cindex @code{string} directive
5345 Copy the characters in @var{str} to the object file. You may specify more than
5346 one string to copy, separated by commas. Unless otherwise specified for a
5347 particular machine, the assembler marks the end of each string with a 0 byte.
5348 You can use any of the escape sequences described in @ref{Strings,,Strings}.
5351 @section @code{.struct @var{expression}}
5353 @cindex @code{struct} directive
5354 Switch to the absolute section, and set the section offset to @var{expression},
5355 which must be an absolute expression. You might use this as follows:
5364 This would define the symbol @code{field1} to have the value 0, the symbol
5365 @code{field2} to have the value 4, and the symbol @code{field3} to have the
5366 value 8. Assembly would be left in the absolute section, and you would need to
5367 use a @code{.section} directive of some sort to change to some other section
5368 before further assembly.
5372 @section @code{.subsection @var{name}}
5374 @cindex @code{.subsection} directive
5375 @cindex Section Stack
5376 This is one of the ELF section stack manipulation directives. The others are
5377 @code{.section} (@pxref{Section}), @code{.pushsection} (@pxref{PushSection}),
5378 @code{.popsection} (@pxref{PopSection}), and @code{.previous}
5381 This directive replaces the current subsection with @code{name}. The current
5382 section is not changed. The replaced subsection is put onto the section stack
5383 in place of the then current top of stack subsection.
5388 @section @code{.symver}
5389 @cindex @code{symver} directive
5390 @cindex symbol versioning
5391 @cindex versions of symbols
5392 Use the @code{.symver} directive to bind symbols to specific version nodes
5393 within a source file. This is only supported on ELF platforms, and is
5394 typically used when assembling files to be linked into a shared library.
5395 There are cases where it may make sense to use this in objects to be bound
5396 into an application itself so as to override a versioned symbol from a
5399 For ELF targets, the @code{.symver} directive can be used like this:
5401 .symver @var{name}, @var{name2@@nodename}
5403 If the symbol @var{name} is defined within the file
5404 being assembled, the @code{.symver} directive effectively creates a symbol
5405 alias with the name @var{name2@@nodename}, and in fact the main reason that we
5406 just don't try and create a regular alias is that the @var{@@} character isn't
5407 permitted in symbol names. The @var{name2} part of the name is the actual name
5408 of the symbol by which it will be externally referenced. The name @var{name}
5409 itself is merely a name of convenience that is used so that it is possible to
5410 have definitions for multiple versions of a function within a single source
5411 file, and so that the compiler can unambiguously know which version of a
5412 function is being mentioned. The @var{nodename} portion of the alias should be
5413 the name of a node specified in the version script supplied to the linker when
5414 building a shared library. If you are attempting to override a versioned
5415 symbol from a shared library, then @var{nodename} should correspond to the
5416 nodename of the symbol you are trying to override.
5418 If the symbol @var{name} is not defined within the file being assembled, all
5419 references to @var{name} will be changed to @var{name2@@nodename}. If no
5420 reference to @var{name} is made, @var{name2@@nodename} will be removed from the
5423 Another usage of the @code{.symver} directive is:
5425 .symver @var{name}, @var{name2@@@@nodename}
5427 In this case, the symbol @var{name} must exist and be defined within
5428 the file being assembled. It is similar to @var{name2@@nodename}. The
5429 difference is @var{name2@@@@nodename} will also be used to resolve
5430 references to @var{name2} by the linker.
5432 The third usage of the @code{.symver} directive is:
5434 .symver @var{name}, @var{name2@@@@@@nodename}
5436 When @var{name} is not defined within the
5437 file being assembled, it is treated as @var{name2@@nodename}. When
5438 @var{name} is defined within the file being assembled, the symbol
5439 name, @var{name}, will be changed to @var{name2@@@@nodename}.
5444 @section @code{.tag @var{structname}}
5446 @cindex COFF structure debugging
5447 @cindex structure debugging, COFF
5448 @cindex @code{tag} directive
5449 This directive is generated by compilers to include auxiliary debugging
5450 information in the symbol table. It is only permitted inside
5451 @code{.def}/@code{.endef} pairs. Tags are used to link structure
5452 definitions in the symbol table with instances of those structures.
5455 @samp{.tag} is only used when generating COFF format output; when
5456 @command{@value{AS}} is generating @code{b.out}, it accepts this directive but
5462 @section @code{.text @var{subsection}}
5464 @cindex @code{text} directive
5465 Tells @command{@value{AS}} to assemble the following statements onto the end of
5466 the text subsection numbered @var{subsection}, which is an absolute
5467 expression. If @var{subsection} is omitted, subsection number zero
5471 @section @code{.title "@var{heading}"}
5473 @cindex @code{title} directive
5474 @cindex listing control: title line
5475 Use @var{heading} as the title (second line, immediately after the
5476 source file name and pagenumber) when generating assembly listings.
5478 This directive affects subsequent pages, as well as the current page if
5479 it appears within ten lines of the top of a page.
5482 @section @code{.type @var{int}} (COFF version)
5484 @cindex COFF symbol type
5485 @cindex symbol type, COFF
5486 @cindex @code{type} directive
5487 This directive, permitted only within @code{.def}/@code{.endef} pairs,
5488 records the integer @var{int} as the type attribute of a symbol table entry.
5491 @samp{.type} is associated only with COFF format output; when
5492 @command{@value{AS}} is configured for @code{b.out} output, it accepts this
5493 directive but ignores it.
5496 @section @code{.type @var{name} , @var{type description}} (ELF version)
5498 @cindex ELF symbol type
5499 @cindex symbol type, ELF
5500 @cindex @code{type} directive
5501 This directive is used to set the type of symbol @var{name} to be either a
5502 function symbol or an object symbol. There are five different syntaxes
5503 supported for the @var{type description} field, in order to provide
5504 compatibility with various other assemblers. The syntaxes supported are:
5507 .type <name>,#function
5508 .type <name>,#object
5510 .type <name>,@@function
5511 .type <name>,@@object
5513 .type <name>,%function
5514 .type <name>,%object
5516 .type <name>,"function"
5517 .type <name>,"object"
5519 .type <name> STT_FUNCTION
5520 .type <name> STT_OBJECT
5524 @section @code{.uleb128 @var{expressions}}
5526 @cindex @code{uleb128} directive
5527 @var{uleb128} stands for ``unsigned little endian base 128.'' This is a
5528 compact, variable length representation of numbers used by the DWARF
5529 symbolic debugging format. @xref{Sleb128,@code{.sleb128}}.
5533 @section @code{.val @var{addr}}
5535 @cindex @code{val} directive
5536 @cindex COFF value attribute
5537 @cindex value attribute, COFF
5538 This directive, permitted only within @code{.def}/@code{.endef} pairs,
5539 records the address @var{addr} as the value attribute of a symbol table
5543 @samp{.val} is used only for COFF output; when @command{@value{AS}} is
5544 configured for @code{b.out}, it accepts this directive but ignores it.
5550 @section @code{.version "@var{string}"}
5552 @cindex @code{.version}
5553 This directive creates a @code{.note} section and places into it an ELF
5554 formatted note of type NT_VERSION. The note's name is set to @code{string}.
5559 @section @code{.vtable_entry @var{table}, @var{offset}}
5561 @cindex @code{.vtable_entry}
5562 This directive finds or creates a symbol @code{table} and creates a
5563 @code{VTABLE_ENTRY} relocation for it with an addend of @code{offset}.
5566 @section @code{.vtable_inherit @var{child}, @var{parent}}
5568 @cindex @code{.vtable_inherit}
5569 This directive finds the symbol @code{child} and finds or creates the symbol
5570 @code{parent} and then creates a @code{VTABLE_INHERIT} relocation for the
5571 parent whose addend is the value of the child symbol. As a special case the
5572 parent name of @code{0} is treated as refering the @code{*ABS*} section.
5577 @section @code{.weak @var{names}}
5579 @cindex @code{.weak}
5580 This directive sets the weak attribute on the comma separated list of symbol
5581 @code{names}. If the symbols do not already exist, they will be created.
5585 @section @code{.word @var{expressions}}
5587 @cindex @code{word} directive
5588 This directive expects zero or more @var{expressions}, of any section,
5589 separated by commas.
5592 For each expression, @command{@value{AS}} emits a 32-bit number.
5595 For each expression, @command{@value{AS}} emits a 16-bit number.
5600 The size of the number emitted, and its byte order,
5601 depend on what target computer the assembly is for.
5604 @c on amd29k, i960, sparc the "special treatment to support compilers" doesn't
5605 @c happen---32-bit addressability, period; no long/short jumps.
5606 @ifset DIFF-TBL-KLUGE
5607 @cindex difference tables altered
5608 @cindex altered difference tables
5610 @emph{Warning: Special Treatment to support Compilers}
5614 Machines with a 32-bit address space, but that do less than 32-bit
5615 addressing, require the following special treatment. If the machine of
5616 interest to you does 32-bit addressing (or doesn't require it;
5617 @pxref{Machine Dependencies}), you can ignore this issue.
5620 In order to assemble compiler output into something that works,
5621 @command{@value{AS}} occasionally does strange things to @samp{.word} directives.
5622 Directives of the form @samp{.word sym1-sym2} are often emitted by
5623 compilers as part of jump tables. Therefore, when @command{@value{AS}} assembles a
5624 directive of the form @samp{.word sym1-sym2}, and the difference between
5625 @code{sym1} and @code{sym2} does not fit in 16 bits, @command{@value{AS}}
5626 creates a @dfn{secondary jump table}, immediately before the next label.
5627 This secondary jump table is preceded by a short-jump to the
5628 first byte after the secondary table. This short-jump prevents the flow
5629 of control from accidentally falling into the new table. Inside the
5630 table is a long-jump to @code{sym2}. The original @samp{.word}
5631 contains @code{sym1} minus the address of the long-jump to
5634 If there were several occurrences of @samp{.word sym1-sym2} before the
5635 secondary jump table, all of them are adjusted. If there was a
5636 @samp{.word sym3-sym4}, that also did not fit in sixteen bits, a
5637 long-jump to @code{sym4} is included in the secondary jump table,
5638 and the @code{.word} directives are adjusted to contain @code{sym3}
5639 minus the address of the long-jump to @code{sym4}; and so on, for as many
5640 entries in the original jump table as necessary.
5643 @emph{This feature may be disabled by compiling @command{@value{AS}} with the
5644 @samp{-DWORKING_DOT_WORD} option.} This feature is likely to confuse
5645 assembly language programmers.
5648 @c end DIFF-TBL-KLUGE
5651 @section Deprecated Directives
5653 @cindex deprecated directives
5654 @cindex obsolescent directives
5655 One day these directives won't work.
5656 They are included for compatibility with older assemblers.
5663 @node Machine Dependencies
5664 @chapter Machine Dependent Features
5666 @cindex machine dependencies
5667 The machine instruction sets are (almost by definition) different on
5668 each machine where @command{@value{AS}} runs. Floating point representations
5669 vary as well, and @command{@value{AS}} often supports a few additional
5670 directives or command-line options for compatibility with other
5671 assemblers on a particular platform. Finally, some versions of
5672 @command{@value{AS}} support special pseudo-instructions for branch
5675 This chapter discusses most of these differences, though it does not
5676 include details on any machine's instruction set. For details on that
5677 subject, see the hardware manufacturer's manual.
5681 * AMD29K-Dependent:: AMD 29K Dependent Features
5684 * Alpha-Dependent:: Alpha Dependent Features
5687 * ARC-Dependent:: ARC Dependent Features
5690 * ARM-Dependent:: ARM Dependent Features
5693 * CRIS-Dependent:: CRIS Dependent Features
5696 * D10V-Dependent:: D10V Dependent Features
5699 * D30V-Dependent:: D30V Dependent Features
5702 * H8/300-Dependent:: Hitachi H8/300 Dependent Features
5705 * H8/500-Dependent:: Hitachi H8/500 Dependent Features
5708 * HPPA-Dependent:: HPPA Dependent Features
5711 * ESA/390-Dependent:: IBM ESA/390 Dependent Features
5714 * i386-Dependent:: Intel 80386 and AMD x86-64 Dependent Features
5717 * i860-Dependent:: Intel 80860 Dependent Features
5720 * i960-Dependent:: Intel 80960 Dependent Features
5723 * IP2K-Dependent:: IP2K Dependent Features
5726 * M32R-Dependent:: M32R Dependent Features
5729 * M68K-Dependent:: M680x0 Dependent Features
5732 * M68HC11-Dependent:: M68HC11 and 68HC12 Dependent Features
5735 * M88K-Dependent:: M880x0 Dependent Features
5738 * MIPS-Dependent:: MIPS Dependent Features
5741 * MMIX-Dependent:: MMIX Dependent Features
5744 * SH-Dependent:: Hitachi SH Dependent Features
5745 * SH64-Dependent:: Hitachi SH64 Dependent Features
5748 * PDP-11-Dependent:: PDP-11 Dependent Features
5751 * PJ-Dependent:: picoJava Dependent Features
5754 * PPC-Dependent:: PowerPC Dependent Features
5757 * Sparc-Dependent:: SPARC Dependent Features
5760 * TIC54X-Dependent:: TI TMS320C54x Dependent Features
5763 * V850-Dependent:: V850 Dependent Features
5766 * Z8000-Dependent:: Z8000 Dependent Features
5769 * Vax-Dependent:: VAX Dependent Features
5776 @c The following major nodes are *sections* in the GENERIC version, *chapters*
5777 @c in single-cpu versions. This is mainly achieved by @lowersections. There is a
5778 @c peculiarity: to preserve cross-references, there must be a node called
5779 @c "Machine Dependencies". Hence the conditional nodenames in each
5780 @c major node below. Node defaulting in makeinfo requires adjacency of
5781 @c node and sectioning commands; hence the repetition of @chapter BLAH
5782 @c in both conditional blocks.
5785 @include c-a29k.texi
5789 @include c-alpha.texi
5801 @include c-cris.texi
5806 @node Machine Dependencies
5807 @chapter Machine Dependent Features
5809 The machine instruction sets are different on each Hitachi chip family,
5810 and there are also some syntax differences among the families. This
5811 chapter describes the specific @command{@value{AS}} features for each
5815 * H8/300-Dependent:: Hitachi H8/300 Dependent Features
5816 * H8/500-Dependent:: Hitachi H8/500 Dependent Features
5817 * SH-Dependent:: Hitachi SH Dependent Features
5824 @include c-d10v.texi
5828 @include c-d30v.texi
5832 @include c-h8300.texi
5836 @include c-h8500.texi
5840 @include c-hppa.texi
5844 @include c-i370.texi
5848 @include c-i386.texi
5852 @include c-i860.texi
5856 @include c-i960.texi
5860 @include c-ia64.texi
5864 @include c-ip2k.texi
5868 @include c-m32r.texi
5872 @include c-m68k.texi
5876 @include c-m68hc11.texi
5880 @include c-m88k.texi
5884 @include c-mips.texi
5888 @include c-mmix.texi
5892 @include c-ns32k.texi
5896 @include c-pdp11.texi
5909 @include c-sh64.texi
5913 @include c-sparc.texi
5917 @include c-tic54x.texi
5929 @include c-v850.texi
5933 @c reverse effect of @down at top of generic Machine-Dep chapter
5937 @node Reporting Bugs
5938 @chapter Reporting Bugs
5939 @cindex bugs in assembler
5940 @cindex reporting bugs in assembler
5942 Your bug reports play an essential role in making @command{@value{AS}} reliable.
5944 Reporting a bug may help you by bringing a solution to your problem, or it may
5945 not. But in any case the principal function of a bug report is to help the
5946 entire community by making the next version of @command{@value{AS}} work better.
5947 Bug reports are your contribution to the maintenance of @command{@value{AS}}.
5949 In order for a bug report to serve its purpose, you must include the
5950 information that enables us to fix the bug.
5953 * Bug Criteria:: Have you found a bug?
5954 * Bug Reporting:: How to report bugs
5958 @section Have you found a bug?
5959 @cindex bug criteria
5961 If you are not sure whether you have found a bug, here are some guidelines:
5964 @cindex fatal signal
5965 @cindex assembler crash
5966 @cindex crash of assembler
5968 If the assembler gets a fatal signal, for any input whatever, that is a
5969 @command{@value{AS}} bug. Reliable assemblers never crash.
5971 @cindex error on valid input
5973 If @command{@value{AS}} produces an error message for valid input, that is a bug.
5975 @cindex invalid input
5977 If @command{@value{AS}} does not produce an error message for invalid input, that
5978 is a bug. However, you should note that your idea of ``invalid input'' might
5979 be our idea of ``an extension'' or ``support for traditional practice''.
5982 If you are an experienced user of assemblers, your suggestions for improvement
5983 of @command{@value{AS}} are welcome in any case.
5987 @section How to report bugs
5989 @cindex assembler bugs, reporting
5991 A number of companies and individuals offer support for @sc{gnu} products. If
5992 you obtained @command{@value{AS}} from a support organization, we recommend you
5993 contact that organization first.
5995 You can find contact information for many support companies and
5996 individuals in the file @file{etc/SERVICE} in the @sc{gnu} Emacs
5999 In any event, we also recommend that you send bug reports for @command{@value{AS}}
6000 to @samp{bug-binutils@@gnu.org}.
6002 The fundamental principle of reporting bugs usefully is this:
6003 @strong{report all the facts}. If you are not sure whether to state a
6004 fact or leave it out, state it!
6006 Often people omit facts because they think they know what causes the problem
6007 and assume that some details do not matter. Thus, you might assume that the
6008 name of a symbol you use in an example does not matter. Well, probably it does
6009 not, but one cannot be sure. Perhaps the bug is a stray memory reference which
6010 happens to fetch from the location where that name is stored in memory;
6011 perhaps, if the name were different, the contents of that location would fool
6012 the assembler into doing the right thing despite the bug. Play it safe and
6013 give a specific, complete example. That is the easiest thing for you to do,
6014 and the most helpful.
6016 Keep in mind that the purpose of a bug report is to enable us to fix the bug if
6017 it is new to us. Therefore, always write your bug reports on the assumption
6018 that the bug has not been reported previously.
6020 Sometimes people give a few sketchy facts and ask, ``Does this ring a
6021 bell?'' Those bug reports are useless, and we urge everyone to
6022 @emph{refuse to respond to them} except to chide the sender to report
6025 To enable us to fix the bug, you should include all these things:
6029 The version of @command{@value{AS}}. @command{@value{AS}} announces it if you start
6030 it with the @samp{--version} argument.
6032 Without this, we will not know whether there is any point in looking for
6033 the bug in the current version of @command{@value{AS}}.
6036 Any patches you may have applied to the @command{@value{AS}} source.
6039 The type of machine you are using, and the operating system name and
6043 What compiler (and its version) was used to compile @command{@value{AS}}---e.g.
6047 The command arguments you gave the assembler to assemble your example and
6048 observe the bug. To guarantee you will not omit something important, list them
6049 all. A copy of the Makefile (or the output from make) is sufficient.
6051 If we were to try to guess the arguments, we would probably guess wrong
6052 and then we might not encounter the bug.
6055 A complete input file that will reproduce the bug. If the bug is observed when
6056 the assembler is invoked via a compiler, send the assembler source, not the
6057 high level language source. Most compilers will produce the assembler source
6058 when run with the @samp{-S} option. If you are using @code{@value{GCC}}, use
6059 the options @samp{-v --save-temps}; this will save the assembler source in a
6060 file with an extension of @file{.s}, and also show you exactly how
6061 @command{@value{AS}} is being run.
6064 A description of what behavior you observe that you believe is
6065 incorrect. For example, ``It gets a fatal signal.''
6067 Of course, if the bug is that @command{@value{AS}} gets a fatal signal, then we
6068 will certainly notice it. But if the bug is incorrect output, we might not
6069 notice unless it is glaringly wrong. You might as well not give us a chance to
6072 Even if the problem you experience is a fatal signal, you should still say so
6073 explicitly. Suppose something strange is going on, such as, your copy of
6074 @command{@value{AS}} is out of synch, or you have encountered a bug in the C
6075 library on your system. (This has happened!) Your copy might crash and ours
6076 would not. If you told us to expect a crash, then when ours fails to crash, we
6077 would know that the bug was not happening for us. If you had not told us to
6078 expect a crash, then we would not be able to draw any conclusion from our
6082 If you wish to suggest changes to the @command{@value{AS}} source, send us context
6083 diffs, as generated by @code{diff} with the @samp{-u}, @samp{-c}, or @samp{-p}
6084 option. Always send diffs from the old file to the new file. If you even
6085 discuss something in the @command{@value{AS}} source, refer to it by context, not
6088 The line numbers in our development sources will not match those in your
6089 sources. Your line numbers would convey no useful information to us.
6092 Here are some things that are not necessary:
6096 A description of the envelope of the bug.
6098 Often people who encounter a bug spend a lot of time investigating
6099 which changes to the input file will make the bug go away and which
6100 changes will not affect it.
6102 This is often time consuming and not very useful, because the way we
6103 will find the bug is by running a single example under the debugger
6104 with breakpoints, not by pure deduction from a series of examples.
6105 We recommend that you save your time for something else.
6107 Of course, if you can find a simpler example to report @emph{instead}
6108 of the original one, that is a convenience for us. Errors in the
6109 output will be easier to spot, running under the debugger will take
6110 less time, and so on.
6112 However, simplification is not vital; if you do not want to do this,
6113 report the bug anyway and send us the entire test case you used.
6116 A patch for the bug.
6118 A patch for the bug does help us if it is a good one. But do not omit
6119 the necessary information, such as the test case, on the assumption that
6120 a patch is all we need. We might see problems with your patch and decide
6121 to fix the problem another way, or we might not understand it at all.
6123 Sometimes with a program as complicated as @command{@value{AS}} it is very hard to
6124 construct an example that will make the program follow a certain path through
6125 the code. If you do not send us the example, we will not be able to construct
6126 one, so we will not be able to verify that the bug is fixed.
6128 And if we cannot understand what bug you are trying to fix, or why your
6129 patch should be an improvement, we will not install it. A test case will
6130 help us to understand.
6133 A guess about what the bug is or what it depends on.
6135 Such guesses are usually wrong. Even we cannot guess right about such
6136 things without first using the debugger to find the facts.
6139 @node Acknowledgements
6140 @chapter Acknowledgements
6142 If you have contributed to @command{@value{AS}} and your name isn't listed here,
6143 it is not meant as a slight. We just don't know about it. Send mail to the
6144 maintainer, and we'll correct the situation. Currently
6146 the maintainer is Ken Raeburn (email address @code{raeburn@@cygnus.com}).
6148 Dean Elsner wrote the original @sc{gnu} assembler for the VAX.@footnote{Any
6151 Jay Fenlason maintained GAS for a while, adding support for GDB-specific debug
6152 information and the 68k series machines, most of the preprocessing pass, and
6153 extensive changes in @file{messages.c}, @file{input-file.c}, @file{write.c}.
6155 K. Richard Pixley maintained GAS for a while, adding various enhancements and
6156 many bug fixes, including merging support for several processors, breaking GAS
6157 up to handle multiple object file format back ends (including heavy rewrite,
6158 testing, an integration of the coff and b.out back ends), adding configuration
6159 including heavy testing and verification of cross assemblers and file splits
6160 and renaming, converted GAS to strictly ANSI C including full prototypes, added
6161 support for m680[34]0 and cpu32, did considerable work on i960 including a COFF
6162 port (including considerable amounts of reverse engineering), a SPARC opcode
6163 file rewrite, DECstation, rs6000, and hp300hpux host ports, updated ``know''
6164 assertions and made them work, much other reorganization, cleanup, and lint.
6166 Ken Raeburn wrote the high-level BFD interface code to replace most of the code
6167 in format-specific I/O modules.
6169 The original VMS support was contributed by David L. Kashtan. Eric Youngdale
6170 has done much work with it since.
6172 The Intel 80386 machine description was written by Eliot Dresselhaus.
6174 Minh Tran-Le at IntelliCorp contributed some AIX 386 support.
6176 The Motorola 88k machine description was contributed by Devon Bowen of Buffalo
6177 University and Torbjorn Granlund of the Swedish Institute of Computer Science.
6179 Keith Knowles at the Open Software Foundation wrote the original MIPS back end
6180 (@file{tc-mips.c}, @file{tc-mips.h}), and contributed Rose format support
6181 (which hasn't been merged in yet). Ralph Campbell worked with the MIPS code to
6182 support a.out format.
6184 Support for the Zilog Z8k and Hitachi H8/300 and H8/500 processors (tc-z8k,
6185 tc-h8300, tc-h8500), and IEEE 695 object file format (obj-ieee), was written by
6186 Steve Chamberlain of Cygnus Support. Steve also modified the COFF back end to
6187 use BFD for some low-level operations, for use with the H8/300 and AMD 29k
6190 John Gilmore built the AMD 29000 support, added @code{.include} support, and
6191 simplified the configuration of which versions accept which directives. He
6192 updated the 68k machine description so that Motorola's opcodes always produced
6193 fixed-size instructions (e.g. @code{jsr}), while synthetic instructions
6194 remained shrinkable (@code{jbsr}). John fixed many bugs, including true tested
6195 cross-compilation support, and one bug in relaxation that took a week and
6196 required the proverbial one-bit fix.
6198 Ian Lance Taylor of Cygnus Support merged the Motorola and MIT syntax for the
6199 68k, completed support for some COFF targets (68k, i386 SVR3, and SCO Unix),
6200 added support for MIPS ECOFF and ELF targets, wrote the initial RS/6000 and
6201 PowerPC assembler, and made a few other minor patches.
6203 Steve Chamberlain made @command{@value{AS}} able to generate listings.
6205 Hewlett-Packard contributed support for the HP9000/300.
6207 Jeff Law wrote GAS and BFD support for the native HPPA object format (SOM)
6208 along with a fairly extensive HPPA testsuite (for both SOM and ELF object
6209 formats). This work was supported by both the Center for Software Science at
6210 the University of Utah and Cygnus Support.
6212 Support for ELF format files has been worked on by Mark Eichin of Cygnus
6213 Support (original, incomplete implementation for SPARC), Pete Hoogenboom and
6214 Jeff Law at the University of Utah (HPPA mainly), Michael Meissner of the Open
6215 Software Foundation (i386 mainly), and Ken Raeburn of Cygnus Support (sparc,
6216 and some initial 64-bit support).
6218 Linas Vepstas added GAS support for the ESA/390 "IBM 370" architecture.
6220 Richard Henderson rewrote the Alpha assembler. Klaus Kaempf wrote GAS and BFD
6221 support for openVMS/Alpha.
6223 Timothy Wall, Michael Hayes, and Greg Smart contributed to the various tic*
6226 Several engineers at Cygnus Support have also provided many small bug fixes and
6227 configuration enhancements.
6229 Many others have contributed large or small bugfixes and enhancements. If
6230 you have contributed significant work and are not mentioned on this list, and
6231 want to be, let us know. Some of the history has been lost; we are not
6232 intentionally leaving anyone out.
6234 @node GNU Free Documentation License
6235 @chapter GNU Free Documentation License
6237 GNU Free Documentation License
6239 Version 1.1, March 2000
6241 Copyright (C) 2000 Free Software Foundation, Inc.
6242 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
6244 Everyone is permitted to copy and distribute verbatim copies
6245 of this license document, but changing it is not allowed.
6250 The purpose of this License is to make a manual, textbook, or other
6251 written document "free" in the sense of freedom: to assure everyone
6252 the effective freedom to copy and redistribute it, with or without
6253 modifying it, either commercially or noncommercially. Secondarily,
6254 this License preserves for the author and publisher a way to get
6255 credit for their work, while not being considered responsible for
6256 modifications made by others.
6258 This License is a kind of "copyleft", which means that derivative
6259 works of the document must themselves be free in the same sense. It
6260 complements the GNU General Public License, which is a copyleft
6261 license designed for free software.
6263 We have designed this License in order to use it for manuals for free
6264 software, because free software needs free documentation: a free
6265 program should come with manuals providing the same freedoms that the
6266 software does. But this License is not limited to software manuals;
6267 it can be used for any textual work, regardless of subject matter or
6268 whether it is published as a printed book. We recommend this License
6269 principally for works whose purpose is instruction or reference.
6272 1. APPLICABILITY AND DEFINITIONS
6274 This License applies to any manual or other work that contains a
6275 notice placed by the copyright holder saying it can be distributed
6276 under the terms of this License. The "Document", below, refers to any
6277 such manual or work. Any member of the public is a licensee, and is
6280 A "Modified Version" of the Document means any work containing the
6281 Document or a portion of it, either copied verbatim, or with
6282 modifications and/or translated into another language.
6284 A "Secondary Section" is a named appendix or a front-matter section of
6285 the Document that deals exclusively with the relationship of the
6286 publishers or authors of the Document to the Document's overall subject
6287 (or to related matters) and contains nothing that could fall directly
6288 within that overall subject. (For example, if the Document is in part a
6289 textbook of mathematics, a Secondary Section may not explain any
6290 mathematics.) The relationship could be a matter of historical
6291 connection with the subject or with related matters, or of legal,
6292 commercial, philosophical, ethical or political position regarding
6295 The "Invariant Sections" are certain Secondary Sections whose titles
6296 are designated, as being those of Invariant Sections, in the notice
6297 that says that the Document is released under this License.
6299 The "Cover Texts" are certain short passages of text that are listed,
6300 as Front-Cover Texts or Back-Cover Texts, in the notice that says that
6301 the Document is released under this License.
6303 A "Transparent" copy of the Document means a machine-readable copy,
6304 represented in a format whose specification is available to the
6305 general public, whose contents can be viewed and edited directly and
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6310 to text formatters. A copy made in an otherwise Transparent file
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6315 Examples of suitable formats for Transparent copies include plain
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6322 machine-generated HTML produced by some word processors for output
6325 The "Title Page" means, for a printed book, the title page itself,
6326 plus such following pages as are needed to hold, legibly, the material
6327 this License requires to appear in the title page. For works in
6328 formats which do not have any title page as such, "Title Page" means
6329 the text near the most prominent appearance of the work's title,
6330 preceding the beginning of the body of the text.
6335 You may copy and distribute the Document in any medium, either
6336 commercially or noncommercially, provided that this License, the
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6338 to the Document are reproduced in all copies, and that you add no other
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6340 technical measures to obstruct or control the reading or further
6341 copying of the copies you make or distribute. However, you may accept
6342 compensation in exchange for copies. If you distribute a large enough
6343 number of copies you must also follow the conditions in section 3.
6345 You may also lend copies, under the same conditions stated above, and
6346 you may publicly display copies.
6349 3. COPYING IN QUANTITY
6351 If you publish printed copies of the Document numbering more than 100,
6352 and the Document's license notice requires Cover Texts, you must enclose
6353 the copies in covers that carry, clearly and legibly, all these Cover
6354 Texts: Front-Cover Texts on the front cover, and Back-Cover Texts on
6355 the back cover. Both covers must also clearly and legibly identify
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6359 Copying with changes limited to the covers, as long as they preserve
6360 the title of the Document and satisfy these conditions, can be treated
6361 as verbatim copying in other respects.
6363 If the required texts for either cover are too voluminous to fit
6364 legibly, you should put the first ones listed (as many as fit
6365 reasonably) on the actual cover, and continue the rest onto adjacent
6368 If you publish or distribute Opaque copies of the Document numbering
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6371 a publicly-accessible computer-network location containing a complete
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6373 general network-using public has access to download anonymously at no
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6376 distribution of Opaque copies in quantity, to ensure that this
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6378 until at least one year after the last time you distribute an Opaque
6379 copy (directly or through your agents or retailers) of that edition to
6382 It is requested, but not required, that you contact the authors of the
6383 Document well before redistributing any large number of copies, to give
6384 them a chance to provide you with an updated version of the Document.
6389 You may copy and distribute a Modified Version of the Document under
6390 the conditions of sections 2 and 3 above, provided that you release
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6396 A. Use in the Title Page (and on the covers, if any) a title distinct
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6401 B. List on the Title Page, as authors, one or more persons or entities
6402 responsible for authorship of the modifications in the Modified
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6404 Document (all of its principal authors, if it has less than five).
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6407 D. Preserve all the copyright notices of the Document.
6408 E. Add an appropriate copyright notice for your modifications
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6410 F. Include, immediately after the copyright notices, a license notice
6411 giving the public permission to use the Modified Version under the
6412 terms of this License, in the form shown in the Addendum below.
6413 G. Preserve in that license notice the full lists of Invariant Sections
6414 and required Cover Texts given in the Document's license notice.
6415 H. Include an unaltered copy of this License.
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6417 it an item stating at least the title, year, new authors, and
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6430 K. In any section entitled "Acknowledgements" or "Dedications",
6431 preserve the section's title, and preserve in the section all the
6432 substance and tone of each of the contributor acknowledgements
6433 and/or dedications given therein.
6434 L. Preserve all the Invariant Sections of the Document,
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6437 M. Delete any section entitled "Endorsements". Such a section
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6439 N. Do not retitle any existing section as "Endorsements"
6440 or to conflict in title with any Invariant Section.
6442 If the Modified Version includes new front-matter sections or
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6445 of these sections as invariant. To do this, add their titles to the
6446 list of Invariant Sections in the Modified Version's license notice.
6447 These titles must be distinct from any other section titles.
6449 You may add a section entitled "Endorsements", provided it contains
6450 nothing but endorsements of your Modified Version by various
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6456 passage of up to 25 words as a Back-Cover Text, to the end of the list
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6465 The author(s) and publisher(s) of the Document do not by this License
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6470 5. COMBINING DOCUMENTS
6472 You may combine the Document with other documents released under this
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6475 Invariant Sections of all of the original documents, unmodified, and
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6485 Make the same adjustment to the section titles in the list of
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6488 In the combination, you must combine any sections entitled "History"
6489 in the various original documents, forming one section entitled
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6492 entitled "Endorsements."
6495 6. COLLECTIONS OF DOCUMENTS
6497 You may make a collection consisting of the Document and other documents
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6501 verbatim copying of each of the documents in all other respects.
6503 You may extract a single document from such a collection, and distribute
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6505 License into the extracted document, and follow this License in all
6506 other respects regarding verbatim copying of that document.
6509 7. AGGREGATION WITH INDEPENDENT WORKS
6511 A compilation of the Document or its derivatives with other separate
6512 and independent documents or works, in or on a volume of a storage or
6513 distribution medium, does not as a whole count as a Modified Version
6514 of the Document, provided no compilation copyright is claimed for the
6515 compilation. Such a compilation is called an "aggregate", and this
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6518 are not themselves derivative works of the Document.
6520 If the Cover Text requirement of section 3 is applicable to these
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6522 of the entire aggregate, the Document's Cover Texts may be placed on
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6524 Otherwise they must appear on covers around the whole aggregate.
6529 Translation is considered a kind of modification, so you may
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6531 Replacing Invariant Sections with translations requires special
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6533 translations of some or all Invariant Sections in addition to the
6534 original versions of these Invariant Sections. You may include a
6535 translation of this License provided that you also include the
6536 original English version of this License. In case of a disagreement
6537 between the translation and the original English version of this
6538 License, the original English version will prevail.
6543 You may not copy, modify, sublicense, or distribute the Document except
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6546 automatically terminate your rights under this License. However,
6547 parties who have received copies, or rights, from you under this
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6549 parties remain in full compliance.
6552 10. FUTURE REVISIONS OF THIS LICENSE
6554 The Free Software Foundation may publish new, revised versions
6555 of the GNU Free Documentation License from time to time. Such new
6556 versions will be similar in spirit to the present version, but may
6557 differ in detail to address new problems or concerns. See
6558 http://www.gnu.org/copyleft/.
6560 Each version of the License is given a distinguishing version number.
6561 If the Document specifies that a particular numbered version of this
6562 License "or any later version" applies to it, you have the option of
6563 following the terms and conditions either of that specified version or
6564 of any later version that has been published (not as a draft) by the
6565 Free Software Foundation. If the Document does not specify a version
6566 number of this License, you may choose any version ever published (not
6567 as a draft) by the Free Software Foundation.
6570 ADDENDUM: How to use this License for your documents
6572 To use this License in a document you have written, include a copy of
6573 the License in the document and put the following copyright and
6574 license notices just after the title page:
6577 Copyright (c) YEAR YOUR NAME.
6578 Permission is granted to copy, distribute and/or modify this document
6579 under the terms of the GNU Free Documentation License, Version 1.1
6580 or any later version published by the Free Software Foundation;
6581 with the Invariant Sections being LIST THEIR TITLES, with the
6582 Front-Cover Texts being LIST, and with the Back-Cover Texts being LIST.
6583 A copy of the license is included in the section entitled "GNU
6584 Free Documentation License".
6587 If you have no Invariant Sections, write "with no Invariant Sections"
6588 instead of saying which ones are invariant. If you have no
6589 Front-Cover Texts, write "no Front-Cover Texts" instead of
6590 "Front-Cover Texts being LIST"; likewise for Back-Cover Texts.
6592 If your document contains nontrivial examples of program code, we
6593 recommend releasing these examples in parallel under your choice of
6594 free software license, such as the GNU General Public License,
6595 to permit their use in free software.
projects / external / binutils.git / blob