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 @c defaults, config file may override:
19 @include asconfig.texi
24 @c Configure for the generation of man pages
56 @c common OR combinations of conditions
76 @set abnormal-separator
80 @settitle Using @value{AS}
83 @settitle Using @value{AS} (@value{TARGET})
85 @setchapternewpage odd
90 @c WARE! Some of the machine-dependent sections contain tables of machine
91 @c instructions. Except in multi-column format, these tables look silly.
92 @c Unfortunately, Texinfo doesn't have a general-purpose multi-col format, so
93 @c the multi-col format is faked within @example sections.
95 @c Again unfortunately, the natural size that fits on a page, for these tables,
96 @c is different depending on whether or not smallbook is turned on.
97 @c This matters, because of order: text flow switches columns at each page
100 @c The format faked in this source works reasonably well for smallbook,
101 @c not well for the default large-page format. This manual expects that if you
102 @c turn on @smallbook, you will also uncomment the "@set SMALL" to enable the
103 @c tables in question. You can turn on one without the other at your
104 @c discretion, of course.
107 @c the insn tables look just as silly in info files regardless of smallbook,
108 @c might as well show 'em anyways.
114 * As: (as). The GNU assembler.
123 This file documents the GNU Assembler "@value{AS}".
125 @c man begin COPYRIGHT
126 Copyright (C) 1991, 92, 93, 94, 95, 96, 97, 98, 99, 2000, 2001 Free Software Foundation, Inc.
128 Permission is granted to copy, distribute and/or modify this document
129 under the terms of the GNU Free Documentation License, Version 1.1
130 or any later version published by the Free Software Foundation;
131 with no Invariant Sections, with no Front-Cover Texts, and with no
132 Back-Cover Texts. A copy of the license is included in the
133 section entitled "GNU Free Documentation License".
138 Permission is granted to process this file through Tex and print the
139 results, provided the printed document carries copying permission
140 notice identical to this one except for the removal of this paragraph
141 (this paragraph not being relevant to the printed manual).
147 @title Using @value{AS}
148 @subtitle The @sc{gnu} Assembler
150 @subtitle for the @value{TARGET} family
153 @subtitle Version @value{VERSION}
156 The Free Software Foundation Inc. thanks The Nice Computer
157 Company of Australia for loaning Dean Elsner to write the
158 first (Vax) version of @code{as} for Project @sc{gnu}.
159 The proprietors, management and staff of TNCCA thank FSF for
160 distracting the boss while they got some work
163 @author Dean Elsner, Jay Fenlason & friends
167 \hfill {\it Using {\tt @value{AS}}}\par
168 \hfill Edited by Cygnus Support\par
170 %"boxit" macro for figures:
171 %Modified from Knuth's ``boxit'' macro from TeXbook (answer to exercise 21.3)
172 \gdef\boxit#1#2{\vbox{\hrule\hbox{\vrule\kern3pt
173 \vbox{\parindent=0pt\parskip=0pt\hsize=#1\kern3pt\strut\hfil
174 #2\hfil\strut\kern3pt}\kern3pt\vrule}\hrule}}%box with visible outline
175 \gdef\ibox#1#2{\hbox to #1{#2\hfil}\kern8pt}% invisible box
178 @vskip 0pt plus 1filll
179 Copyright @copyright{} 1991, 92, 93, 94, 95, 96, 97, 98, 99, 2000, 2001 Free Software Foundation, Inc.
181 Permission is granted to copy, distribute and/or modify this document
182 under the terms of the GNU Free Documentation License, Version 1.1
183 or any later version published by the Free Software Foundation;
184 with no Invariant Sections, with no Front-Cover Texts, and with no
185 Back-Cover Texts. A copy of the license is included in the
186 section entitled "GNU Free Documentation License".
192 @top Using @value{AS}
194 This file is a user guide to the @sc{gnu} assembler @code{@value{AS}} version
197 This version of the file describes @code{@value{AS}} configured to generate
198 code for @value{TARGET} architectures.
201 This document is distributed under the terms of the GNU Free
202 Documentation License. A copy of the license is included in the
203 section entitled "GNU Free Documentation License".
206 * Overview:: Overview
207 * Invoking:: Command-Line Options
209 * Sections:: Sections and Relocation
211 * Expressions:: Expressions
212 * Pseudo Ops:: Assembler Directives
213 * Machine Dependencies:: Machine Dependent Features
214 * Reporting Bugs:: Reporting Bugs
215 * Acknowledgements:: Who Did What
216 * GNU Free Documentation License:: GNU Free Documentation License
224 This manual is a user guide to the @sc{gnu} assembler @code{@value{AS}}.
226 This version of the manual describes @code{@value{AS}} configured to generate
227 code for @value{TARGET} architectures.
231 @cindex invocation summary
232 @cindex option summary
233 @cindex summary of options
234 Here is a brief summary of how to invoke @code{@value{AS}}. For details,
235 @pxref{Invoking,,Comand-Line Options}.
237 @c man title AS the portable GNU assembler.
240 gcc(1), ld(1), and the Info entries for @file{binutils} and @file{ld}.
243 @c We don't use deffn and friends for the following because they seem
244 @c to be limited to one line for the header.
246 @c man begin SYNOPSIS
247 @value{AS} [ -a[cdhlns][=file] ] [ -D ] [ --defsym @var{sym}=@var{val} ]
248 [ -f ] [ --gstabs ] [ --gdwarf2 ] [ --help ] [ -I @var{dir} ]
250 [ --listing--lhs-width=NUM ][ --listing-lhs-width2=NUM ]
251 [ --listing-rhs-width=NUM ][ --listing-cont-lines=NUM ]
252 [ --keep-locals ] [ -o @var{objfile} ] [ -R ] [ --statistics ] [ -v ]
253 [ -version ] [ --version ] [ -W ] [ --warn ] [ --fatal-warnings ]
254 [ -w ] [ -x ] [ -Z ] [ --target-help ]
256 @c am29k has no machine-dependent assembler options
263 [ -m[arm]1 | -m[arm]2 | -m[arm]250 | -m[arm]3 |
264 -m[arm]6 | -m[arm]60 | -m[arm]600 | -m[arm]610 |
265 -m[arm]620 | -m[arm]7[t][[d]m[i]][fe] | -m[arm]70 |
266 -m[arm]700 | -m[arm]710[c] | -m[arm]7100 |
267 -m[arm]7500 | -m[arm]8 | -m[arm]810 | -m[arm]9 |
268 -m[arm]920 | -m[arm]920t | -m[arm]9tdmi |
269 -mstrongarm | -mstrongarm110 | -mstrongarm1100 ]
270 [ -m[arm]v2 | -m[arm]v2a | -m[arm]v3 | -m[arm]v3m |
271 -m[arm]v4 | -m[arm]v4t | -m[arm]v5 | -[arm]v5t |
274 [ -mfpa10 | -mfpa11 | -mfpe-old | -mno-fpu ]
276 [ -mapcs-32 | -mapcs-26 | -mapcs-float |
278 [ -mthumb-interwork ] [ -moabi ] [ -k ]
287 @c Hitachi family chips have no machine-dependent assembler options
290 @c HPPA has no machine-dependent assembler options (yet).
296 [ -mpwrx | -mpwr2 | -mpwr | -m601 | -mppc | -mppc32 | -m603 | -m604 |
297 -m403 | -m405 | -mppc64 | -m620 | -mppc64bridge | -mbooke |
298 -mbooke32 | -mbooke64 ]
299 [ -mcom | -many | -maltivec ] [ -memb ]
300 [ -mregnames | -mno-regnames ]
301 [ -mrelocatable | -mrelocatable-lib ]
302 [ -mlittle | -mlittle-endian | -mbig, -mbig-endian ]
303 [ -msolaris | -mno-solaris ]
306 @c The order here is important. See c-sparc.texi.
307 [ -Av6 | -Av7 | -Av8 | -Asparclet | -Asparclite
308 -Av8plus | -Av8plusa | -Av9 | -Av9a ]
309 [ -xarch=v8plus | -xarch=v8plusa ] [ -bump ]
313 [ -mcpu=54[123589] | -mcpu=54[56]lp ] [ -mfar-mode | -mf ]
314 [ -merrors-to-file <filename> | -me <filename> ]
317 @c Z8000 has no machine-dependent assembler options
320 @c see md_parse_option in tc-i960.c
321 [ -ACA | -ACA_A | -ACB | -ACC | -AKA | -AKB |
326 [ --m32rx | --[no-]warn-explicit-parallel-conflicts |
330 [ -l ] [ -m68000 | -m68010 | -m68020 | ... ]
333 [ -jsri2bsr ] [ -sifilter ] [ -relax ]
337 [ -m68hc11 | -m68hc12 ]
338 [ --force-long-branchs ] [ --short-branchs ]
339 [ --strict-direct-mode ] [ --print-insn-syntax ]
340 [ --print-opcodes ] [ --generate-example ]
343 [ -nocpp ] [ -EL ] [ -EB ] [ -G @var{num} ] [ -mcpu=@var{CPU} ]
344 [ -mips1 ] [ -mips2 ] [ -mips3 ] [ -mips4 ] [ -mips5 ]
345 [ -mips32 ] [ -mips64 ]
346 [ -m4650 ] [ -no-m4650 ]
347 [ --trap ] [ --break ] [ -n ]
348 [ --emulation=@var{name} ]
350 [ -- | @var{files} @dots{} ]
358 Turn on listings, in any of a variety of ways:
362 omit false conditionals
365 omit debugging directives
368 include high-level source
374 include macro expansions
377 omit forms processing
383 set the name of the listing file
386 You may combine these options; for example, use @samp{-aln} for assembly
387 listing without forms processing. The @samp{=file} option, if used, must be
388 the last one. By itself, @samp{-a} defaults to @samp{-ahls}.
391 Ignored. This option is accepted for script compatibility with calls to
394 @item --defsym @var{sym}=@var{value}
395 Define the symbol @var{sym} to be @var{value} before assembling the input file.
396 @var{value} must be an integer constant. As in C, a leading @samp{0x}
397 indicates a hexadecimal value, and a leading @samp{0} indicates an octal value.
400 ``fast''---skip whitespace and comment preprocessing (assume source is
404 Generate stabs debugging information for each assembler line. This
405 may help debugging assembler code, if the debugger can handle it.
408 Generate DWARF2 debugging information for each assembler line. This
409 may help debugging assembler code, if the debugger can handle it. Note - this
410 option is only supported by some targets, not all of them.
413 Print a summary of the command line options and exit.
416 Print a summary of all target specific options and exit.
419 Add directory @var{dir} to the search list for @code{.include} directives.
422 Don't warn about signed overflow.
425 @ifclear DIFF-TBL-KLUGE
426 This option is accepted but has no effect on the @value{TARGET} family.
428 @ifset DIFF-TBL-KLUGE
429 Issue warnings when difference tables altered for long displacements.
434 Keep (in the symbol table) local symbols. On traditional a.out systems
435 these start with @samp{L}, but different systems have different local
438 @item --listing-lhs-width=@var{number}
439 Set the maximum width, in words, of the output data column for an assembler
440 listing to @var{number}.
442 @item --listing-lhs-width2=@var{number}
443 Set the maximum width, in words, of the output data column for continuation
444 lines in an assembler listing to @var{number}.
446 @item --listing-rhs-width=@var{number}
447 Set the maximum width of an input source line, as displayed in a listing, to
450 @item --listing-cont-lines=@var{number}
451 Set the maximum number of lines printed in a listing for a single line of input
454 @item -o @var{objfile}
455 Name the object-file output from @code{@value{AS}} @var{objfile}.
458 Fold the data section into the text section.
461 Print the maximum space (in bytes) and total time (in seconds) used by
464 @item --strip-local-absolute
465 Remove local absolute symbols from the outgoing symbol table.
469 Print the @code{as} version.
472 Print the @code{as} version and exit.
476 Suppress warning messages.
478 @item --fatal-warnings
479 Treat warnings as errors.
482 Don't suppress warning messages or treat them as errors.
491 Generate an object file even after errors.
493 @item -- | @var{files} @dots{}
494 Standard input, or source files to assemble.
499 The following options are available when @value{AS} is configured for
504 This option selects the core processor variant.
506 Select either big-endian (-EB) or little-endian (-EL) output.
511 The following options are available when @value{AS} is configured for the ARM
515 @item -m[arm][1|2|3|6|7|8|9][...]
516 Specify which ARM processor variant is the target.
517 @item -m[arm]v[2|2a|3|3m|4|4t|5|5t]
518 Specify which ARM architecture variant is used by the target.
519 @item -mthumb | -mall
520 Enable or disable Thumb only instruction decoding.
521 @item -mfpa10 | -mfpa11 | -mfpe-old | -mno-fpu
522 Select which Floating Point architecture is the target.
523 @item -mapcs-32 | -mapcs-26 | -mapcs-float | -mapcs-reentrant | -moabi
524 Select which procedure calling convention is in use.
526 Select either big-endian (-EB) or little-endian (-EL) output.
527 @item -mthumb-interwork
528 Specify that the code has been generated with interworking between Thumb and
531 Specify that PIC code has been generated.
536 The following options are available when @value{AS} is configured for
539 @cindex D10V optimization
540 @cindex optimization, D10V
542 Optimize output by parallelizing instructions.
547 The following options are available when @value{AS} is configured for a D30V
550 @cindex D30V optimization
551 @cindex optimization, D30V
553 Optimize output by parallelizing instructions.
557 Warn when nops are generated.
559 @cindex D30V nops after 32-bit multiply
561 Warn when a nop after a 32-bit multiply instruction is generated.
566 The following options are available when @value{AS} is configured for the
567 Intel 80960 processor.
570 @item -ACA | -ACA_A | -ACB | -ACC | -AKA | -AKB | -AKC | -AMC
571 Specify which variant of the 960 architecture is the target.
574 Add code to collect statistics about branches taken.
577 Do not alter compare-and-branch instructions for long displacements;
584 The following options are available when @value{AS} is configured for the
585 Mitsubishi M32R series.
590 Specify which processor in the M32R family is the target. The default
591 is normally the M32R, but this option changes it to the M32RX.
593 @item --warn-explicit-parallel-conflicts or --Wp
594 Produce warning messages when questionable parallel constructs are
597 @item --no-warn-explicit-parallel-conflicts or --Wnp
598 Do not produce warning messages when questionable parallel constructs are
605 The following options are available when @value{AS} is configured for the
606 Motorola 68000 series.
611 Shorten references to undefined symbols, to one word instead of two.
613 @item -m68000 | -m68008 | -m68010 | -m68020 | -m68030
614 @itemx | -m68040 | -m68060 | -m68302 | -m68331 | -m68332
615 @itemx | -m68333 | -m68340 | -mcpu32 | -m5200
616 Specify what processor in the 68000 family is the target. The default
617 is normally the 68020, but this can be changed at configuration time.
619 @item -m68881 | -m68882 | -mno-68881 | -mno-68882
620 The target machine does (or does not) have a floating-point coprocessor.
621 The default is to assume a coprocessor for 68020, 68030, and cpu32. Although
622 the basic 68000 is not compatible with the 68881, a combination of the
623 two can be specified, since it's possible to do emulation of the
624 coprocessor instructions with the main processor.
626 @item -m68851 | -mno-68851
627 The target machine does (or does not) have a memory-management
628 unit coprocessor. The default is to assume an MMU for 68020 and up.
635 For details about the PDP-11 machine dependent features options,
636 see @ref{PDP-11-Options}.
639 @item -mpic | -mno-pic
640 Generate position-independent (or position-dependent) code. The
641 default is @code{-mpic}.
644 @itemx -mall-extensions
645 Enable all instruction set extensions. This is the default.
647 @item -mno-extensions
648 Disable all instruction set extensions.
650 @item -m@var{extension} | -mno-@var{extension}
651 Enable (or disable) a particular instruction set extension.
654 Enable the instruction set extensions supported by a particular CPU, and
655 disable all other extensions.
657 @item -m@var{machine}
658 Enable the instruction set extensions supported by a particular machine
659 model, and disable all other extensions.
665 The following options are available when @value{AS} is configured for
666 a picoJava processor.
670 @cindex PJ endianness
671 @cindex endianness, PJ
672 @cindex big endian output, PJ
674 Generate ``big endian'' format output.
676 @cindex little endian output, PJ
678 Generate ``little endian'' format output.
684 The following options are available when @value{AS} is configured for the
685 Motorola 68HC11 or 68HC12 series.
689 @item -m68hc11 | -m68hc12
690 Specify what processor is the target. The default is
691 defined by the configuration option when building the assembler.
693 @item --force-long-branchs
694 Relative branches are turned into absolute ones. This concerns
695 conditional branches, unconditional branches and branches to a
698 @item -S | --short-branchs
699 Do not turn relative branchs into absolute ones
700 when the offset is out of range.
702 @item --strict-direct-mode
703 Do not turn the direct addressing mode into extended addressing mode
704 when the instruction does not support direct addressing mode.
706 @item --print-insn-syntax
707 Print the syntax of instruction in case of error.
709 @item --print-opcodes
710 print the list of instructions with syntax and then exit.
712 @item --generate-example
713 print an example of instruction for each possible instruction and then exit.
714 This option is only useful for testing @code{@value{AS}}.
720 The following options are available when @code{@value{AS}} is configured
721 for the SPARC architecture:
724 @item -Av6 | -Av7 | -Av8 | -Asparclet | -Asparclite
725 @itemx -Av8plus | -Av8plusa | -Av9 | -Av9a
726 Explicitly select a variant of the SPARC architecture.
728 @samp{-Av8plus} and @samp{-Av8plusa} select a 32 bit environment.
729 @samp{-Av9} and @samp{-Av9a} select a 64 bit environment.
731 @samp{-Av8plusa} and @samp{-Av9a} enable the SPARC V9 instruction set with
732 UltraSPARC extensions.
734 @item -xarch=v8plus | -xarch=v8plusa
735 For compatibility with the Solaris v9 assembler. These options are
736 equivalent to -Av8plus and -Av8plusa, respectively.
739 Warn when the assembler switches to another architecture.
744 The following options are available when @value{AS} is configured for the 'c54x
749 Enable extended addressing mode. All addresses and relocations will assume
750 extended addressing (usually 23 bits).
751 @item -mcpu=@var{CPU_VERSION}
752 Sets the CPU version being compiled for.
753 @item -merrors-to-file @var{FILENAME}
754 Redirect error output to a file, for broken systems which don't support such
755 behaviour in the shell.
760 The following options are available when @value{AS} is configured for
765 This option sets the largest size of an object that can be referenced
766 implicitly with the @code{gp} register. It is only accepted for targets that
767 use ECOFF format, such as a DECstation running Ultrix. The default value is 8.
769 @cindex MIPS endianness
770 @cindex endianness, MIPS
771 @cindex big endian output, MIPS
773 Generate ``big endian'' format output.
775 @cindex little endian output, MIPS
777 Generate ``little endian'' format output.
786 Generate code for a particular MIPS Instruction Set Architecture level.
787 @samp{-mips1} corresponds to the @sc{r2000} and @sc{r3000} processors,
788 @samp{-mips2} to the @sc{r6000} processor, and @samp{-mips3} to the @sc{r4000}
790 @samp{-mips5}, @samp{-mips32}, and @samp{-mips64} correspond
791 to generic @sc{MIPS V}, @sc{MIPS32}, and @sc{MIPS64} ISA
792 processors, respectively.
796 Generate code for the MIPS @sc{r4650} chip. This tells the assembler to accept
797 the @samp{mad} and @samp{madu} instruction, and to not schedule @samp{nop}
798 instructions around accesses to the @samp{HI} and @samp{LO} registers.
799 @samp{-no-m4650} turns off this option.
801 @item -mcpu=@var{CPU}
802 Generate code for a particular MIPS cpu. It is exactly equivalent to
803 @samp{-m@var{cpu}}, except that there are more value of @var{cpu}
807 @item --emulation=@var{name}
808 This option causes @code{@value{AS}} to emulate @code{@value{AS}} configured
809 for some other target, in all respects, including output format (choosing
810 between ELF and ECOFF only), handling of pseudo-opcodes which may generate
811 debugging information or store symbol table information, and default
812 endianness. The available configuration names are: @samp{mipsecoff},
813 @samp{mipself}, @samp{mipslecoff}, @samp{mipsbecoff}, @samp{mipslelf},
814 @samp{mipsbelf}. The first two do not alter the default endianness from that
815 of the primary target for which the assembler was configured; the others change
816 the default to little- or big-endian as indicated by the @samp{b} or @samp{l}
817 in the name. Using @samp{-EB} or @samp{-EL} will override the endianness
818 selection in any case.
820 This option is currently supported only when the primary target
821 @code{@value{AS}} is configured for is a MIPS ELF or ECOFF target.
822 Furthermore, the primary target or others specified with
823 @samp{--enable-targets=@dots{}} at configuration time must include support for
824 the other format, if both are to be available. For example, the Irix 5
825 configuration includes support for both.
827 Eventually, this option will support more configurations, with more
828 fine-grained control over the assembler's behavior, and will be supported for
832 @code{@value{AS}} ignores this option. It is accepted for compatibility with
840 Control how to deal with multiplication overflow and division by zero.
841 @samp{--trap} or @samp{--no-break} (which are synonyms) take a trap exception
842 (and only work for Instruction Set Architecture level 2 and higher);
843 @samp{--break} or @samp{--no-trap} (also synonyms, and the default) take a
847 When this option is used, @code{@value{AS}} will issue a warning every
848 time it generates a nop instruction from a macro.
853 The following options are available when @value{AS} is configured for
859 Enable or disable the JSRI to BSR transformation. By default this is enabled.
860 The command line option @samp{-nojsri2bsr} can be used to disable it.
864 Enable or disable the silicon filter behaviour. By default this is disabled.
865 The default can be overridden by the @samp{-sifilter} command line option.
868 Alter jump instructions for long displacements.
870 @item -mcpu=[210|340]
871 Select the cpu type on the target hardware. This controls which instructions
875 Assemble for a big endian target.
878 Assemble for a little endian target.
886 * Manual:: Structure of this Manual
887 * GNU Assembler:: The GNU Assembler
888 * Object Formats:: Object File Formats
889 * Command Line:: Command Line
890 * Input Files:: Input Files
891 * Object:: Output (Object) File
892 * Errors:: Error and Warning Messages
896 @section Structure of this Manual
898 @cindex manual, structure and purpose
899 This manual is intended to describe what you need to know to use
900 @sc{gnu} @code{@value{AS}}. We cover the syntax expected in source files, including
901 notation for symbols, constants, and expressions; the directives that
902 @code{@value{AS}} understands; and of course how to invoke @code{@value{AS}}.
905 We also cover special features in the @value{TARGET}
906 configuration of @code{@value{AS}}, including assembler directives.
909 This manual also describes some of the machine-dependent features of
910 various flavors of the assembler.
913 @cindex machine instructions (not covered)
914 On the other hand, this manual is @emph{not} intended as an introduction
915 to programming in assembly language---let alone programming in general!
916 In a similar vein, we make no attempt to introduce the machine
917 architecture; we do @emph{not} describe the instruction set, standard
918 mnemonics, registers or addressing modes that are standard to a
919 particular architecture.
921 You may want to consult the manufacturer's
922 machine architecture manual for this information.
926 For information on the H8/300 machine instruction set, see @cite{H8/300
927 Series Programming Manual} (Hitachi ADE--602--025). For the H8/300H,
928 see @cite{H8/300H Series Programming Manual} (Hitachi).
931 For information on the H8/500 machine instruction set, see @cite{H8/500
932 Series Programming Manual} (Hitachi M21T001).
935 For information on the Hitachi SH machine instruction set, see
936 @cite{SH-Microcomputer User's Manual} (Hitachi Micro Systems, Inc.).
939 For information on the Z8000 machine instruction set, see @cite{Z8000 CPU Technical Manual}
943 @c I think this is premature---doc@cygnus.com, 17jan1991
945 Throughout this manual, we assume that you are running @dfn{GNU},
946 the portable operating system from the @dfn{Free Software
947 Foundation, Inc.}. This restricts our attention to certain kinds of
948 computer (in particular, the kinds of computers that @sc{gnu} can run on);
949 once this assumption is granted examples and definitions need less
952 @code{@value{AS}} is part of a team of programs that turn a high-level
953 human-readable series of instructions into a low-level
954 computer-readable series of instructions. Different versions of
955 @code{@value{AS}} are used for different kinds of computer.
958 @c There used to be a section "Terminology" here, which defined
959 @c "contents", "byte", "word", and "long". Defining "word" to any
960 @c particular size is confusing when the .word directive may generate 16
961 @c bits on one machine and 32 bits on another; in general, for the user
962 @c version of this manual, none of these terms seem essential to define.
963 @c They were used very little even in the former draft of the manual;
964 @c this draft makes an effort to avoid them (except in names of
968 @section The GNU Assembler
970 @c man begin DESCRIPTION
972 @sc{gnu} @code{as} is really a family of assemblers.
974 This manual describes @code{@value{AS}}, a member of that family which is
975 configured for the @value{TARGET} architectures.
977 If you use (or have used) the @sc{gnu} assembler on one architecture, you
978 should find a fairly similar environment when you use it on another
979 architecture. Each version has much in common with the others,
980 including object file formats, most assembler directives (often called
981 @dfn{pseudo-ops}) and assembler syntax.@refill
983 @cindex purpose of @sc{gnu} assembler
984 @code{@value{AS}} is primarily intended to assemble the output of the
985 @sc{gnu} C compiler @code{@value{GCC}} for use by the linker
986 @code{@value{LD}}. Nevertheless, we've tried to make @code{@value{AS}}
987 assemble correctly everything that other assemblers for the same
988 machine would assemble.
990 Any exceptions are documented explicitly (@pxref{Machine Dependencies}).
993 @c This remark should appear in generic version of manual; assumption
994 @c here is that generic version sets M680x0.
995 This doesn't mean @code{@value{AS}} always uses the same syntax as another
996 assembler for the same architecture; for example, we know of several
997 incompatible versions of 680x0 assembly language syntax.
1002 Unlike older assemblers, @code{@value{AS}} is designed to assemble a source
1003 program in one pass of the source file. This has a subtle impact on the
1004 @kbd{.org} directive (@pxref{Org,,@code{.org}}).
1006 @node Object Formats
1007 @section Object File Formats
1009 @cindex object file format
1010 The @sc{gnu} assembler can be configured to produce several alternative
1011 object file formats. For the most part, this does not affect how you
1012 write assembly language programs; but directives for debugging symbols
1013 are typically different in different file formats. @xref{Symbol
1014 Attributes,,Symbol Attributes}.
1017 On the @value{TARGET}, @code{@value{AS}} is configured to produce
1018 @value{OBJ-NAME} format object files.
1020 @c The following should exhaust all configs that set MULTI-OBJ, ideally
1022 On the @value{TARGET}, @code{@value{AS}} can be configured to produce either
1023 @code{a.out} or COFF format object files.
1026 On the @value{TARGET}, @code{@value{AS}} can be configured to produce either
1027 @code{b.out} or COFF format object files.
1030 On the @value{TARGET}, @code{@value{AS}} can be configured to produce either
1031 SOM or ELF format object files.
1036 @section Command Line
1038 @cindex command line conventions
1040 After the program name @code{@value{AS}}, the command line may contain
1041 options and file names. Options may appear in any order, and may be
1042 before, after, or between file names. The order of file names is
1045 @cindex standard input, as input file
1047 @file{--} (two hyphens) by itself names the standard input file
1048 explicitly, as one of the files for @code{@value{AS}} to assemble.
1050 @cindex options, command line
1051 Except for @samp{--} any command line argument that begins with a
1052 hyphen (@samp{-}) is an option. Each option changes the behavior of
1053 @code{@value{AS}}. No option changes the way another option works. An
1054 option is a @samp{-} followed by one or more letters; the case of
1055 the letter is important. All options are optional.
1057 Some options expect exactly one file name to follow them. The file
1058 name may either immediately follow the option's letter (compatible
1059 with older assemblers) or it may be the next command argument (@sc{gnu}
1060 standard). These two command lines are equivalent:
1063 @value{AS} -o my-object-file.o mumble.s
1064 @value{AS} -omy-object-file.o mumble.s
1068 @section Input Files
1071 @cindex source program
1072 @cindex files, input
1073 We use the phrase @dfn{source program}, abbreviated @dfn{source}, to
1074 describe the program input to one run of @code{@value{AS}}. The program may
1075 be in one or more files; how the source is partitioned into files
1076 doesn't change the meaning of the source.
1078 @c I added "con" prefix to "catenation" just to prove I can overcome my
1079 @c APL training... doc@cygnus.com
1080 The source program is a concatenation of the text in all the files, in the
1083 @c man begin DESCRIPTION
1084 Each time you run @code{@value{AS}} it assembles exactly one source
1085 program. The source program is made up of one or more files.
1086 (The standard input is also a file.)
1088 You give @code{@value{AS}} a command line that has zero or more input file
1089 names. The input files are read (from left file name to right). A
1090 command line argument (in any position) that has no special meaning
1091 is taken to be an input file name.
1093 If you give @code{@value{AS}} no file names it attempts to read one input file
1094 from the @code{@value{AS}} standard input, which is normally your terminal. You
1095 may have to type @key{ctl-D} to tell @code{@value{AS}} there is no more program
1098 Use @samp{--} if you need to explicitly name the standard input file
1099 in your command line.
1101 If the source is empty, @code{@value{AS}} produces a small, empty object
1106 @subheading Filenames and Line-numbers
1108 @cindex input file linenumbers
1109 @cindex line numbers, in input files
1110 There are two ways of locating a line in the input file (or files) and
1111 either may be used in reporting error messages. One way refers to a line
1112 number in a physical file; the other refers to a line number in a
1113 ``logical'' file. @xref{Errors, ,Error and Warning Messages}.
1115 @dfn{Physical files} are those files named in the command line given
1116 to @code{@value{AS}}.
1118 @dfn{Logical files} are simply names declared explicitly by assembler
1119 directives; they bear no relation to physical files. Logical file names help
1120 error messages reflect the original source file, when @code{@value{AS}} source
1121 is itself synthesized from other files. @code{@value{AS}} understands the
1122 @samp{#} directives emitted by the @code{@value{GCC}} preprocessor. See also
1123 @ref{File,,@code{.file}}.
1126 @section Output (Object) File
1132 Every time you run @code{@value{AS}} it produces an output file, which is
1133 your assembly language program translated into numbers. This file
1134 is the object file. Its default name is
1142 @code{b.out} when @code{@value{AS}} is configured for the Intel 80960.
1144 You can give it another name by using the @code{-o} option. Conventionally,
1145 object file names end with @file{.o}. The default name is used for historical
1146 reasons: older assemblers were capable of assembling self-contained programs
1147 directly into a runnable program. (For some formats, this isn't currently
1148 possible, but it can be done for the @code{a.out} format.)
1152 The object file is meant for input to the linker @code{@value{LD}}. It contains
1153 assembled program code, information to help @code{@value{LD}} integrate
1154 the assembled program into a runnable file, and (optionally) symbolic
1155 information for the debugger.
1157 @c link above to some info file(s) like the description of a.out.
1158 @c don't forget to describe @sc{gnu} info as well as Unix lossage.
1161 @section Error and Warning Messages
1163 @c man begin DESCRIPTION
1165 @cindex error messages
1166 @cindex warning messages
1167 @cindex messages from assembler
1168 @code{@value{AS}} may write warnings and error messages to the standard error
1169 file (usually your terminal). This should not happen when a compiler
1170 runs @code{@value{AS}} automatically. Warnings report an assumption made so
1171 that @code{@value{AS}} could keep assembling a flawed program; errors report a
1172 grave problem that stops the assembly.
1176 @cindex format of warning messages
1177 Warning messages have the format
1180 file_name:@b{NNN}:Warning Message Text
1184 @cindex line numbers, in warnings/errors
1185 (where @b{NNN} is a line number). If a logical file name has been given
1186 (@pxref{File,,@code{.file}}) it is used for the filename, otherwise the name of
1187 the current input file is used. If a logical line number was given
1189 (@pxref{Line,,@code{.line}})
1193 (@pxref{Line,,@code{.line}})
1196 (@pxref{Ln,,@code{.ln}})
1199 then it is used to calculate the number printed,
1200 otherwise the actual line in the current source file is printed. The
1201 message text is intended to be self explanatory (in the grand Unix
1204 @cindex format of error messages
1205 Error messages have the format
1207 file_name:@b{NNN}:FATAL:Error Message Text
1209 The file name and line number are derived as for warning
1210 messages. The actual message text may be rather less explanatory
1211 because many of them aren't supposed to happen.
1214 @chapter Command-Line Options
1216 @cindex options, all versions of assembler
1217 This chapter describes command-line options available in @emph{all}
1218 versions of the @sc{gnu} assembler; @pxref{Machine Dependencies}, for options specific
1220 to the @value{TARGET}.
1223 to particular machine architectures.
1226 @c man begin DESCRIPTION
1228 If you are invoking @code{@value{AS}} via the @sc{gnu} C compiler (version 2),
1229 you can use the @samp{-Wa} option to pass arguments through to the assembler.
1230 The assembler arguments must be separated from each other (and the @samp{-Wa})
1231 by commas. For example:
1234 gcc -c -g -O -Wa,-alh,-L file.c
1238 This passes two options to the assembler: @samp{-alh} (emit a listing to
1239 standard output with with high-level and assembly source) and @samp{-L} (retain
1240 local symbols in the symbol table).
1242 Usually you do not need to use this @samp{-Wa} mechanism, since many compiler
1243 command-line options are automatically passed to the assembler by the compiler.
1244 (You can call the @sc{gnu} compiler driver with the @samp{-v} option to see
1245 precisely what options it passes to each compilation pass, including the
1251 * a:: -a[cdhlns] enable listings
1252 * D:: -D for compatibility
1253 * f:: -f to work faster
1254 * I:: -I for .include search path
1255 @ifclear DIFF-TBL-KLUGE
1256 * K:: -K for compatibility
1258 @ifset DIFF-TBL-KLUGE
1259 * K:: -K for difference tables
1262 * L:: -L to retain local labels
1263 * listing:: --listing-XXX to configure listing output
1264 * M:: -M or --mri to assemble in MRI compatibility mode
1265 * MD:: --MD for dependency tracking
1266 * o:: -o to name the object file
1267 * R:: -R to join data and text sections
1268 * statistics:: --statistics to see statistics about assembly
1269 * traditional-format:: --traditional-format for compatible output
1270 * v:: -v to announce version
1271 * W:: -W, --no-warn, --warn, --fatal-warnings to control warnings
1272 * Z:: -Z to make object file even after errors
1276 @section Enable Listings: @code{-a[cdhlns]}
1285 @cindex listings, enabling
1286 @cindex assembly listings, enabling
1288 These options enable listing output from the assembler. By itself,
1289 @samp{-a} requests high-level, assembly, and symbols listing.
1290 You can use other letters to select specific options for the list:
1291 @samp{-ah} requests a high-level language listing,
1292 @samp{-al} requests an output-program assembly listing, and
1293 @samp{-as} requests a symbol table listing.
1294 High-level listings require that a compiler debugging option like
1295 @samp{-g} be used, and that assembly listings (@samp{-al}) be requested
1298 Use the @samp{-ac} option to omit false conditionals from a listing. Any lines
1299 which are not assembled because of a false @code{.if} (or @code{.ifdef}, or any
1300 other conditional), or a true @code{.if} followed by an @code{.else}, will be
1301 omitted from the listing.
1303 Use the @samp{-ad} option to omit debugging directives from the
1306 Once you have specified one of these options, you can further control
1307 listing output and its appearance using the directives @code{.list},
1308 @code{.nolist}, @code{.psize}, @code{.eject}, @code{.title}, and
1310 The @samp{-an} option turns off all forms processing.
1311 If you do not request listing output with one of the @samp{-a} options, the
1312 listing-control directives have no effect.
1314 The letters after @samp{-a} may be combined into one option,
1315 @emph{e.g.}, @samp{-aln}.
1317 Note if the assembler source is coming from the standard input (eg because it
1318 is being created by @code{@value{GCC}} and the @samp{-pipe} command line switch
1319 is being used) then the listing will not contain any comments or preprocessor
1320 directives. This is because the listing code buffers input source lines from
1321 stdin only after they have been preprocessed by the assembler. This reduces
1322 memory usage and makes the code more efficient.
1328 This option has no effect whatsoever, but it is accepted to make it more
1329 likely that scripts written for other assemblers also work with
1333 @section Work Faster: @code{-f}
1336 @cindex trusted compiler
1337 @cindex faster processing (@code{-f})
1338 @samp{-f} should only be used when assembling programs written by a
1339 (trusted) compiler. @samp{-f} stops the assembler from doing whitespace
1340 and comment preprocessing on
1341 the input file(s) before assembling them. @xref{Preprocessing,
1345 @emph{Warning:} if you use @samp{-f} when the files actually need to be
1346 preprocessed (if they contain comments, for example), @code{@value{AS}} does
1351 @section @code{.include} search path: @code{-I} @var{path}
1353 @kindex -I @var{path}
1354 @cindex paths for @code{.include}
1355 @cindex search path for @code{.include}
1356 @cindex @code{include} directive search path
1357 Use this option to add a @var{path} to the list of directories
1358 @code{@value{AS}} searches for files specified in @code{.include}
1359 directives (@pxref{Include,,@code{.include}}). You may use @code{-I} as
1360 many times as necessary to include a variety of paths. The current
1361 working directory is always searched first; after that, @code{@value{AS}}
1362 searches any @samp{-I} directories in the same order as they were
1363 specified (left to right) on the command line.
1366 @section Difference Tables: @code{-K}
1369 @ifclear DIFF-TBL-KLUGE
1370 On the @value{TARGET} family, this option is allowed, but has no effect. It is
1371 permitted for compatibility with the @sc{gnu} assembler on other platforms,
1372 where it can be used to warn when the assembler alters the machine code
1373 generated for @samp{.word} directives in difference tables. The @value{TARGET}
1374 family does not have the addressing limitations that sometimes lead to this
1375 alteration on other platforms.
1378 @ifset DIFF-TBL-KLUGE
1379 @cindex difference tables, warning
1380 @cindex warning for altered difference tables
1381 @code{@value{AS}} sometimes alters the code emitted for directives of the form
1382 @samp{.word @var{sym1}-@var{sym2}}; @pxref{Word,,@code{.word}}.
1383 You can use the @samp{-K} option if you want a warning issued when this
1388 @section Include Local Labels: @code{-L}
1391 @cindex local labels, retaining in output
1392 Labels beginning with @samp{L} (upper case only) are called @dfn{local
1393 labels}. @xref{Symbol Names}. Normally you do not see such labels when
1394 debugging, because they are intended for the use of programs (like
1395 compilers) that compose assembler programs, not for your notice.
1396 Normally both @code{@value{AS}} and @code{@value{LD}} discard such labels, so you do not
1397 normally debug with them.
1399 This option tells @code{@value{AS}} to retain those @samp{L@dots{}} symbols
1400 in the object file. Usually if you do this you also tell the linker
1401 @code{@value{LD}} to preserve symbols whose names begin with @samp{L}.
1403 By default, a local label is any label beginning with @samp{L}, but each
1404 target is allowed to redefine the local label prefix.
1406 On the HPPA local labels begin with @samp{L$}.
1410 @section Configuring listing output: @code{--listing}
1412 The listing feature of the assembler can be enabled via the command line switch
1413 @samp{-a} (@pxref{a}). This feature combines the input source file(s) with a
1414 hex dump of the corresponding locations in the output object file, and displays
1415 them as a listing file. The format of this listing can be controlled by pseudo
1416 ops inside the assembler source (@pxref{List} @pxref{Title} @pxref{Sbttl}
1417 @pxref{Psize} @pxref{Eject}) and also by the following switches:
1420 @item --listing-lhs-width=@samp{number}
1421 @kindex --listing-lhs-width
1422 @cindex Width of first line disassembly output
1423 Sets the maximum width, in words, of the first line of the hex byte dump. This
1424 dump appears on the left hand side of the listing output.
1426 @item --listing-lhs-width2=@samp{number}
1427 @kindex --listing-lhs-width2
1428 @cindex Width of continuation lines of disassembly output
1429 Sets the maximum width, in words, of any further lines of the hex byte dump for
1430 a given inut source line. If this value is not specified, it defaults to being
1431 the same as the value specified for @samp{--listing-lhs-width}. If neither
1432 switch is used the default is to one.
1434 @item --listing-rhs-width=@samp{number}
1435 @kindex --listing-rhs-width
1436 @cindex Width of source line output
1437 Sets the maximum width, in characters, of the source line that is displayed
1438 alongside the hex dump. The default value for this parameter is 100. The
1439 source line is displayed on the right hand side of the listing output.
1441 @item --listing-cont-lines=@samp{number}
1442 @kindex --listing-cont-lines
1443 @cindex Maximum number of continuation lines
1444 Sets the maximum number of continuation lines of hex dump that will be
1445 displayed for a given single line of source input. The default value is 4.
1449 @section Assemble in MRI Compatibility Mode: @code{-M}
1452 @cindex MRI compatibility mode
1453 The @code{-M} or @code{--mri} option selects MRI compatibility mode. This
1454 changes the syntax and pseudo-op handling of @code{@value{AS}} to make it
1455 compatible with the @code{ASM68K} or the @code{ASM960} (depending upon the
1456 configured target) assembler from Microtec Research. The exact nature of the
1457 MRI syntax will not be documented here; see the MRI manuals for more
1458 information. Note in particular that the handling of macros and macro
1459 arguments is somewhat different. The purpose of this option is to permit
1460 assembling existing MRI assembler code using @code{@value{AS}}.
1462 The MRI compatibility is not complete. Certain operations of the MRI assembler
1463 depend upon its object file format, and can not be supported using other object
1464 file formats. Supporting these would require enhancing each object file format
1465 individually. These are:
1468 @item global symbols in common section
1470 The m68k MRI assembler supports common sections which are merged by the linker.
1471 Other object file formats do not support this. @code{@value{AS}} handles
1472 common sections by treating them as a single common symbol. It permits local
1473 symbols to be defined within a common section, but it can not support global
1474 symbols, since it has no way to describe them.
1476 @item complex relocations
1478 The MRI assemblers support relocations against a negated section address, and
1479 relocations which combine the start addresses of two or more sections. These
1480 are not support by other object file formats.
1482 @item @code{END} pseudo-op specifying start address
1484 The MRI @code{END} pseudo-op permits the specification of a start address.
1485 This is not supported by other object file formats. The start address may
1486 instead be specified using the @code{-e} option to the linker, or in a linker
1489 @item @code{IDNT}, @code{.ident} and @code{NAME} pseudo-ops
1491 The MRI @code{IDNT}, @code{.ident} and @code{NAME} pseudo-ops assign a module
1492 name to the output file. This is not supported by other object file formats.
1494 @item @code{ORG} pseudo-op
1496 The m68k MRI @code{ORG} pseudo-op begins an absolute section at a given
1497 address. This differs from the usual @code{@value{AS}} @code{.org} pseudo-op,
1498 which changes the location within the current section. Absolute sections are
1499 not supported by other object file formats. The address of a section may be
1500 assigned within a linker script.
1503 There are some other features of the MRI assembler which are not supported by
1504 @code{@value{AS}}, typically either because they are difficult or because they
1505 seem of little consequence. Some of these may be supported in future releases.
1509 @item EBCDIC strings
1511 EBCDIC strings are not supported.
1513 @item packed binary coded decimal
1515 Packed binary coded decimal is not supported. This means that the @code{DC.P}
1516 and @code{DCB.P} pseudo-ops are not supported.
1518 @item @code{FEQU} pseudo-op
1520 The m68k @code{FEQU} pseudo-op is not supported.
1522 @item @code{NOOBJ} pseudo-op
1524 The m68k @code{NOOBJ} pseudo-op is not supported.
1526 @item @code{OPT} branch control options
1528 The m68k @code{OPT} branch control options---@code{B}, @code{BRS}, @code{BRB},
1529 @code{BRL}, and @code{BRW}---are ignored. @code{@value{AS}} automatically
1530 relaxes all branches, whether forward or backward, to an appropriate size, so
1531 these options serve no purpose.
1533 @item @code{OPT} list control options
1535 The following m68k @code{OPT} list control options are ignored: @code{C},
1536 @code{CEX}, @code{CL}, @code{CRE}, @code{E}, @code{G}, @code{I}, @code{M},
1537 @code{MEX}, @code{MC}, @code{MD}, @code{X}.
1539 @item other @code{OPT} options
1541 The following m68k @code{OPT} options are ignored: @code{NEST}, @code{O},
1542 @code{OLD}, @code{OP}, @code{P}, @code{PCO}, @code{PCR}, @code{PCS}, @code{R}.
1544 @item @code{OPT} @code{D} option is default
1546 The m68k @code{OPT} @code{D} option is the default, unlike the MRI assembler.
1547 @code{OPT NOD} may be used to turn it off.
1549 @item @code{XREF} pseudo-op.
1551 The m68k @code{XREF} pseudo-op is ignored.
1553 @item @code{.debug} pseudo-op
1555 The i960 @code{.debug} pseudo-op is not supported.
1557 @item @code{.extended} pseudo-op
1559 The i960 @code{.extended} pseudo-op is not supported.
1561 @item @code{.list} pseudo-op.
1563 The various options of the i960 @code{.list} pseudo-op are not supported.
1565 @item @code{.optimize} pseudo-op
1567 The i960 @code{.optimize} pseudo-op is not supported.
1569 @item @code{.output} pseudo-op
1571 The i960 @code{.output} pseudo-op is not supported.
1573 @item @code{.setreal} pseudo-op
1575 The i960 @code{.setreal} pseudo-op is not supported.
1580 @section Dependency tracking: @code{--MD}
1583 @cindex dependency tracking
1586 @code{@value{AS}} can generate a dependency file for the file it creates. This
1587 file consists of a single rule suitable for @code{make} describing the
1588 dependencies of the main source file.
1590 The rule is written to the file named in its argument.
1592 This feature is used in the automatic updating of makefiles.
1595 @section Name the Object File: @code{-o}
1598 @cindex naming object file
1599 @cindex object file name
1600 There is always one object file output when you run @code{@value{AS}}. By
1601 default it has the name
1604 @file{a.out} (or @file{b.out}, for Intel 960 targets only).
1618 You use this option (which takes exactly one filename) to give the
1619 object file a different name.
1621 Whatever the object file is called, @code{@value{AS}} overwrites any
1622 existing file of the same name.
1625 @section Join Data and Text Sections: @code{-R}
1628 @cindex data and text sections, joining
1629 @cindex text and data sections, joining
1630 @cindex joining text and data sections
1631 @cindex merging text and data sections
1632 @code{-R} tells @code{@value{AS}} to write the object file as if all
1633 data-section data lives in the text section. This is only done at
1634 the very last moment: your binary data are the same, but data
1635 section parts are relocated differently. The data section part of
1636 your object file is zero bytes long because all its bytes are
1637 appended to the text section. (@xref{Sections,,Sections and Relocation}.)
1639 When you specify @code{-R} it would be possible to generate shorter
1640 address displacements (because we do not have to cross between text and
1641 data section). We refrain from doing this simply for compatibility with
1642 older versions of @code{@value{AS}}. In future, @code{-R} may work this way.
1645 When @code{@value{AS}} is configured for COFF output,
1646 this option is only useful if you use sections named @samp{.text} and
1651 @code{-R} is not supported for any of the HPPA targets. Using
1652 @code{-R} generates a warning from @code{@value{AS}}.
1656 @section Display Assembly Statistics: @code{--statistics}
1658 @kindex --statistics
1659 @cindex statistics, about assembly
1660 @cindex time, total for assembly
1661 @cindex space used, maximum for assembly
1662 Use @samp{--statistics} to display two statistics about the resources used by
1663 @code{@value{AS}}: the maximum amount of space allocated during the assembly
1664 (in bytes), and the total execution time taken for the assembly (in @sc{cpu}
1667 @node traditional-format
1668 @section Compatible output: @code{--traditional-format}
1670 @kindex --traditional-format
1671 For some targets, the output of @code{@value{AS}} is different in some ways
1672 from the output of some existing assembler. This switch requests
1673 @code{@value{AS}} to use the traditional format instead.
1675 For example, it disables the exception frame optimizations which
1676 @code{@value{AS}} normally does by default on @code{@value{GCC}} output.
1679 @section Announce Version: @code{-v}
1683 @cindex assembler version
1684 @cindex version of assembler
1685 You can find out what version of as is running by including the
1686 option @samp{-v} (which you can also spell as @samp{-version}) on the
1690 @section Control Warnings: @code{-W}, @code{--warn}, @code{--no-warn}, @code{--fatal-warnings}
1692 @code{@value{AS}} should never give a warning or error message when
1693 assembling compiler output. But programs written by people often
1694 cause @code{@value{AS}} to give a warning that a particular assumption was
1695 made. All such warnings are directed to the standard error file.
1698 @kindex @samp{--no-warn}
1699 @cindex suppressing warnings
1700 @cindex warnings, suppressing
1701 If you use the @code{-W} and @code{--no-warn} options, no warnings are issued.
1702 This only affects the warning messages: it does not change any particular of
1703 how @code{@value{AS}} assembles your file. Errors, which stop the assembly,
1706 @kindex @samp{--fatal-warnings}
1707 @cindex errors, caused by warnings
1708 @cindex warnings, causing error
1709 If you use the @code{--fatal-warnings} option, @code{@value{AS}} considers
1710 files that generate warnings to be in error.
1712 @kindex @samp{--warn}
1713 @cindex warnings, switching on
1714 You can switch these options off again by specifying @code{--warn}, which
1715 causes warnings to be output as usual.
1718 @section Generate Object File in Spite of Errors: @code{-Z}
1719 @cindex object file, after errors
1720 @cindex errors, continuing after
1721 After an error message, @code{@value{AS}} normally produces no output. If for
1722 some reason you are interested in object file output even after
1723 @code{@value{AS}} gives an error message on your program, use the @samp{-Z}
1724 option. If there are any errors, @code{@value{AS}} continues anyways, and
1725 writes an object file after a final warning message of the form @samp{@var{n}
1726 errors, @var{m} warnings, generating bad object file.}
1731 @cindex machine-independent syntax
1732 @cindex syntax, machine-independent
1733 This chapter describes the machine-independent syntax allowed in a
1734 source file. @code{@value{AS}} syntax is similar to what many other
1735 assemblers use; it is inspired by the BSD 4.2
1740 assembler, except that @code{@value{AS}} does not assemble Vax bit-fields.
1744 * Preprocessing:: Preprocessing
1745 * Whitespace:: Whitespace
1746 * Comments:: Comments
1747 * Symbol Intro:: Symbols
1748 * Statements:: Statements
1749 * Constants:: Constants
1753 @section Preprocessing
1755 @cindex preprocessing
1756 The @code{@value{AS}} internal preprocessor:
1758 @cindex whitespace, removed by preprocessor
1760 adjusts and removes extra whitespace. It leaves one space or tab before
1761 the keywords on a line, and turns any other whitespace on the line into
1764 @cindex comments, removed by preprocessor
1766 removes all comments, replacing them with a single space, or an
1767 appropriate number of newlines.
1769 @cindex constants, converted by preprocessor
1771 converts character constants into the appropriate numeric values.
1774 It does not do macro processing, include file handling, or
1775 anything else you may get from your C compiler's preprocessor. You can
1776 do include file processing with the @code{.include} directive
1777 (@pxref{Include,,@code{.include}}). You can use the @sc{gnu} C compiler driver
1778 to get other ``CPP'' style preprocessing, by giving the input file a
1779 @samp{.S} suffix. @xref{Overall Options,, Options Controlling the Kind of
1780 Output, gcc.info, Using GNU CC}.
1782 Excess whitespace, comments, and character constants
1783 cannot be used in the portions of the input text that are not
1786 @cindex turning preprocessing on and off
1787 @cindex preprocessing, turning on and off
1790 If the first line of an input file is @code{#NO_APP} or if you use the
1791 @samp{-f} option, whitespace and comments are not removed from the input file.
1792 Within an input file, you can ask for whitespace and comment removal in
1793 specific portions of the by putting a line that says @code{#APP} before the
1794 text that may contain whitespace or comments, and putting a line that says
1795 @code{#NO_APP} after this text. This feature is mainly intend to support
1796 @code{asm} statements in compilers whose output is otherwise free of comments
1803 @dfn{Whitespace} is one or more blanks or tabs, in any order.
1804 Whitespace is used to separate symbols, and to make programs neater for
1805 people to read. Unless within character constants
1806 (@pxref{Characters,,Character Constants}), any whitespace means the same
1807 as exactly one space.
1813 There are two ways of rendering comments to @code{@value{AS}}. In both
1814 cases the comment is equivalent to one space.
1816 Anything from @samp{/*} through the next @samp{*/} is a comment.
1817 This means you may not nest these comments.
1821 The only way to include a newline ('\n') in a comment
1822 is to use this sort of comment.
1825 /* This sort of comment does not nest. */
1828 @cindex line comment character
1829 Anything from the @dfn{line comment} character to the next newline
1830 is considered a comment and is ignored. The line comment character is
1832 @samp{;} for the AMD 29K family;
1835 @samp{;} on the ARC;
1838 @samp{@@} on the ARM;
1841 @samp{;} for the H8/300 family;
1844 @samp{!} for the H8/500 family;
1847 @samp{;} for the HPPA;
1850 @samp{#} on the i386 and x86-64;
1853 @samp{#} on the i960;
1856 @samp{;} for the PDP-11;
1859 @samp{;} for picoJava;
1862 @samp{;} for Motorola PowerPC;
1865 @samp{!} for the Hitachi SH;
1868 @samp{!} on the SPARC;
1871 @samp{#} on the m32r;
1874 @samp{|} on the 680x0;
1877 @samp{#} on the 68HC11 and 68HC12;
1880 @samp{;} on the M880x0;
1883 @samp{#} on the Vax;
1886 @samp{!} for the Z8000;
1889 @samp{#} on the V850;
1891 see @ref{Machine Dependencies}. @refill
1892 @c FIXME What about i860?
1895 On some machines there are two different line comment characters. One
1896 character only begins a comment if it is the first non-whitespace character on
1897 a line, while the other always begins a comment.
1901 The V850 assembler also supports a double dash as starting a comment that
1902 extends to the end of the line.
1908 @cindex lines starting with @code{#}
1909 @cindex logical line numbers
1910 To be compatible with past assemblers, lines that begin with @samp{#} have a
1911 special interpretation. Following the @samp{#} should be an absolute
1912 expression (@pxref{Expressions}): the logical line number of the @emph{next}
1913 line. Then a string (@pxref{Strings,, Strings}) is allowed: if present it is a
1914 new logical file name. The rest of the line, if any, should be whitespace.
1916 If the first non-whitespace characters on the line are not numeric,
1917 the line is ignored. (Just like a comment.)
1920 # This is an ordinary comment.
1921 # 42-6 "new_file_name" # New logical file name
1922 # This is logical line # 36.
1924 This feature is deprecated, and may disappear from future versions
1925 of @code{@value{AS}}.
1930 @cindex characters used in symbols
1931 @ifclear SPECIAL-SYMS
1932 A @dfn{symbol} is one or more characters chosen from the set of all
1933 letters (both upper and lower case), digits and the three characters
1939 A @dfn{symbol} is one or more characters chosen from the set of all
1940 letters (both upper and lower case), digits and the three characters
1941 @samp{._$}. (Save that, on the H8/300 only, you may not use @samp{$} in
1947 On most machines, you can also use @code{$} in symbol names; exceptions
1948 are noted in @ref{Machine Dependencies}.
1950 No symbol may begin with a digit. Case is significant.
1951 There is no length limit: all characters are significant. Symbols are
1952 delimited by characters not in that set, or by the beginning of a file
1953 (since the source program must end with a newline, the end of a file is
1954 not a possible symbol delimiter). @xref{Symbols}.
1955 @cindex length of symbols
1960 @cindex statements, structure of
1961 @cindex line separator character
1962 @cindex statement separator character
1964 @ifclear abnormal-separator
1965 A @dfn{statement} ends at a newline character (@samp{\n}) or at a
1966 semicolon (@samp{;}). The newline or semicolon is considered part of
1967 the preceding statement. Newlines and semicolons within character
1968 constants are an exception: they do not end statements.
1970 @ifset abnormal-separator
1972 A @dfn{statement} ends at a newline character (@samp{\n}) or an ``at''
1973 sign (@samp{@@}). The newline or at sign is considered part of the
1974 preceding statement. Newlines and at signs within character constants
1975 are an exception: they do not end statements.
1978 A @dfn{statement} ends at a newline character (@samp{\n}) or an exclamation
1979 point (@samp{!}). The newline or exclamation point is considered part of the
1980 preceding statement. Newlines and exclamation points within character
1981 constants are an exception: they do not end statements.
1984 A @dfn{statement} ends at a newline character (@samp{\n}); or (for the
1985 H8/300) a dollar sign (@samp{$}); or (for the
1988 (@samp{;}). The newline or separator character is considered part of
1989 the preceding statement. Newlines and separators within character
1990 constants are an exception: they do not end statements.
1995 A @dfn{statement} ends at a newline character (@samp{\n}) or line
1996 separator character. (The line separator is usually @samp{;}, unless
1997 this conflicts with the comment character; @pxref{Machine Dependencies}.) The
1998 newline or separator character is considered part of the preceding
1999 statement. Newlines and separators within character constants are an
2000 exception: they do not end statements.
2003 @cindex newline, required at file end
2004 @cindex EOF, newline must precede
2005 It is an error to end any statement with end-of-file: the last
2006 character of any input file should be a newline.@refill
2008 An empty statement is allowed, and may include whitespace. It is ignored.
2010 @cindex instructions and directives
2011 @cindex directives and instructions
2012 @c "key symbol" is not used elsewhere in the document; seems pedantic to
2013 @c @defn{} it in that case, as was done previously... doc@cygnus.com,
2015 A statement begins with zero or more labels, optionally followed by a
2016 key symbol which determines what kind of statement it is. The key
2017 symbol determines the syntax of the rest of the statement. If the
2018 symbol begins with a dot @samp{.} then the statement is an assembler
2019 directive: typically valid for any computer. If the symbol begins with
2020 a letter the statement is an assembly language @dfn{instruction}: it
2021 assembles into a machine language instruction.
2023 Different versions of @code{@value{AS}} for different computers
2024 recognize different instructions. In fact, the same symbol may
2025 represent a different instruction in a different computer's assembly
2029 @cindex @code{:} (label)
2030 @cindex label (@code{:})
2031 A label is a symbol immediately followed by a colon (@code{:}).
2032 Whitespace before a label or after a colon is permitted, but you may not
2033 have whitespace between a label's symbol and its colon. @xref{Labels}.
2036 For HPPA targets, labels need not be immediately followed by a colon, but
2037 the definition of a label must begin in column zero. This also implies that
2038 only one label may be defined on each line.
2042 label: .directive followed by something
2043 another_label: # This is an empty statement.
2044 instruction operand_1, operand_2, @dots{}
2051 A constant is a number, written so that its value is known by
2052 inspection, without knowing any context. Like this:
2055 .byte 74, 0112, 092, 0x4A, 0X4a, 'J, '\J # All the same value.
2056 .ascii "Ring the bell\7" # A string constant.
2057 .octa 0x123456789abcdef0123456789ABCDEF0 # A bignum.
2058 .float 0f-314159265358979323846264338327\
2059 95028841971.693993751E-40 # - pi, a flonum.
2064 * Characters:: Character Constants
2065 * Numbers:: Number Constants
2069 @subsection Character Constants
2071 @cindex character constants
2072 @cindex constants, character
2073 There are two kinds of character constants. A @dfn{character} stands
2074 for one character in one byte and its value may be used in
2075 numeric expressions. String constants (properly called string
2076 @emph{literals}) are potentially many bytes and their values may not be
2077 used in arithmetic expressions.
2081 * Chars:: Characters
2085 @subsubsection Strings
2087 @cindex string constants
2088 @cindex constants, string
2089 A @dfn{string} is written between double-quotes. It may contain
2090 double-quotes or null characters. The way to get special characters
2091 into a string is to @dfn{escape} these characters: precede them with
2092 a backslash @samp{\} character. For example @samp{\\} represents
2093 one backslash: the first @code{\} is an escape which tells
2094 @code{@value{AS}} to interpret the second character literally as a backslash
2095 (which prevents @code{@value{AS}} from recognizing the second @code{\} as an
2096 escape character). The complete list of escapes follows.
2098 @cindex escape codes, character
2099 @cindex character escape codes
2102 @c Mnemonic for ACKnowledge; for ASCII this is octal code 007.
2104 @cindex @code{\b} (backspace character)
2105 @cindex backspace (@code{\b})
2107 Mnemonic for backspace; for ASCII this is octal code 010.
2110 @c Mnemonic for EOText; for ASCII this is octal code 004.
2112 @cindex @code{\f} (formfeed character)
2113 @cindex formfeed (@code{\f})
2115 Mnemonic for FormFeed; for ASCII this is octal code 014.
2117 @cindex @code{\n} (newline character)
2118 @cindex newline (@code{\n})
2120 Mnemonic for newline; for ASCII this is octal code 012.
2123 @c Mnemonic for prefix; for ASCII this is octal code 033, usually known as @code{escape}.
2125 @cindex @code{\r} (carriage return character)
2126 @cindex carriage return (@code{\r})
2128 Mnemonic for carriage-Return; for ASCII this is octal code 015.
2131 @c Mnemonic for space; for ASCII this is octal code 040. Included for compliance with
2132 @c other assemblers.
2134 @cindex @code{\t} (tab)
2135 @cindex tab (@code{\t})
2137 Mnemonic for horizontal Tab; for ASCII this is octal code 011.
2140 @c Mnemonic for Vertical tab; for ASCII this is octal code 013.
2141 @c @item \x @var{digit} @var{digit} @var{digit}
2142 @c A hexadecimal character code. The numeric code is 3 hexadecimal digits.
2144 @cindex @code{\@var{ddd}} (octal character code)
2145 @cindex octal character code (@code{\@var{ddd}})
2146 @item \ @var{digit} @var{digit} @var{digit}
2147 An octal character code. The numeric code is 3 octal digits.
2148 For compatibility with other Unix systems, 8 and 9 are accepted as digits:
2149 for example, @code{\008} has the value 010, and @code{\009} the value 011.
2151 @cindex @code{\@var{xd...}} (hex character code)
2152 @cindex hex character code (@code{\@var{xd...}})
2153 @item \@code{x} @var{hex-digits...}
2154 A hex character code. All trailing hex digits are combined. Either upper or
2155 lower case @code{x} works.
2157 @cindex @code{\\} (@samp{\} character)
2158 @cindex backslash (@code{\\})
2160 Represents one @samp{\} character.
2163 @c Represents one @samp{'} (accent acute) character.
2164 @c This is needed in single character literals
2165 @c (@xref{Characters,,Character Constants}.) to represent
2168 @cindex @code{\"} (doublequote character)
2169 @cindex doublequote (@code{\"})
2171 Represents one @samp{"} character. Needed in strings to represent
2172 this character, because an unescaped @samp{"} would end the string.
2174 @item \ @var{anything-else}
2175 Any other character when escaped by @kbd{\} gives a warning, but
2176 assembles as if the @samp{\} was not present. The idea is that if
2177 you used an escape sequence you clearly didn't want the literal
2178 interpretation of the following character. However @code{@value{AS}} has no
2179 other interpretation, so @code{@value{AS}} knows it is giving you the wrong
2180 code and warns you of the fact.
2183 Which characters are escapable, and what those escapes represent,
2184 varies widely among assemblers. The current set is what we think
2185 the BSD 4.2 assembler recognizes, and is a subset of what most C
2186 compilers recognize. If you are in doubt, do not use an escape
2190 @subsubsection Characters
2192 @cindex single character constant
2193 @cindex character, single
2194 @cindex constant, single character
2195 A single character may be written as a single quote immediately
2196 followed by that character. The same escapes apply to characters as
2197 to strings. So if you want to write the character backslash, you
2198 must write @kbd{'\\} where the first @code{\} escapes the second
2199 @code{\}. As you can see, the quote is an acute accent, not a
2200 grave accent. A newline
2202 @ifclear abnormal-separator
2203 (or semicolon @samp{;})
2205 @ifset abnormal-separator
2207 (or at sign @samp{@@})
2210 (or dollar sign @samp{$}, for the H8/300; or semicolon @samp{;} for the
2216 immediately following an acute accent is taken as a literal character
2217 and does not count as the end of a statement. The value of a character
2218 constant in a numeric expression is the machine's byte-wide code for
2219 that character. @code{@value{AS}} assumes your character code is ASCII:
2220 @kbd{'A} means 65, @kbd{'B} means 66, and so on. @refill
2223 @subsection Number Constants
2225 @cindex constants, number
2226 @cindex number constants
2227 @code{@value{AS}} distinguishes three kinds of numbers according to how they
2228 are stored in the target machine. @emph{Integers} are numbers that
2229 would fit into an @code{int} in the C language. @emph{Bignums} are
2230 integers, but they are stored in more than 32 bits. @emph{Flonums}
2231 are floating point numbers, described below.
2234 * Integers:: Integers
2239 * Bit Fields:: Bit Fields
2245 @subsubsection Integers
2247 @cindex constants, integer
2249 @cindex binary integers
2250 @cindex integers, binary
2251 A binary integer is @samp{0b} or @samp{0B} followed by zero or more of
2252 the binary digits @samp{01}.
2254 @cindex octal integers
2255 @cindex integers, octal
2256 An octal integer is @samp{0} followed by zero or more of the octal
2257 digits (@samp{01234567}).
2259 @cindex decimal integers
2260 @cindex integers, decimal
2261 A decimal integer starts with a non-zero digit followed by zero or
2262 more digits (@samp{0123456789}).
2264 @cindex hexadecimal integers
2265 @cindex integers, hexadecimal
2266 A hexadecimal integer is @samp{0x} or @samp{0X} followed by one or
2267 more hexadecimal digits chosen from @samp{0123456789abcdefABCDEF}.
2269 Integers have the usual values. To denote a negative integer, use
2270 the prefix operator @samp{-} discussed under expressions
2271 (@pxref{Prefix Ops,,Prefix Operators}).
2274 @subsubsection Bignums
2277 @cindex constants, bignum
2278 A @dfn{bignum} has the same syntax and semantics as an integer
2279 except that the number (or its negative) takes more than 32 bits to
2280 represent in binary. The distinction is made because in some places
2281 integers are permitted while bignums are not.
2284 @subsubsection Flonums
2286 @cindex floating point numbers
2287 @cindex constants, floating point
2289 @cindex precision, floating point
2290 A @dfn{flonum} represents a floating point number. The translation is
2291 indirect: a decimal floating point number from the text is converted by
2292 @code{@value{AS}} to a generic binary floating point number of more than
2293 sufficient precision. This generic floating point number is converted
2294 to a particular computer's floating point format (or formats) by a
2295 portion of @code{@value{AS}} specialized to that computer.
2297 A flonum is written by writing (in order)
2302 (@samp{0} is optional on the HPPA.)
2306 A letter, to tell @code{@value{AS}} the rest of the number is a flonum.
2308 @kbd{e} is recommended. Case is not important.
2310 @c FIXME: verify if flonum syntax really this vague for most cases
2311 (Any otherwise illegal letter works here, but that might be changed. Vax BSD
2312 4.2 assembler seems to allow any of @samp{defghDEFGH}.)
2315 On the H8/300, H8/500,
2317 and AMD 29K architectures, the letter must be
2318 one of the letters @samp{DFPRSX} (in upper or lower case).
2320 On the ARC, the letter must be one of the letters @samp{DFRS}
2321 (in upper or lower case).
2323 On the Intel 960 architecture, the letter must be
2324 one of the letters @samp{DFT} (in upper or lower case).
2326 On the HPPA architecture, the letter must be @samp{E} (upper case only).
2330 One of the letters @samp{DFPRSX} (in upper or lower case).
2333 One of the letters @samp{DFRS} (in upper or lower case).
2336 One of the letters @samp{DFPRSX} (in upper or lower case).
2339 The letter @samp{E} (upper case only).
2342 One of the letters @samp{DFT} (in upper or lower case).
2347 An optional sign: either @samp{+} or @samp{-}.
2350 An optional @dfn{integer part}: zero or more decimal digits.
2353 An optional @dfn{fractional part}: @samp{.} followed by zero
2354 or more decimal digits.
2357 An optional exponent, consisting of:
2361 An @samp{E} or @samp{e}.
2362 @c I can't find a config where "EXP_CHARS" is other than 'eE', but in
2363 @c principle this can perfectly well be different on different targets.
2365 Optional sign: either @samp{+} or @samp{-}.
2367 One or more decimal digits.
2372 At least one of the integer part or the fractional part must be
2373 present. The floating point number has the usual base-10 value.
2375 @code{@value{AS}} does all processing using integers. Flonums are computed
2376 independently of any floating point hardware in the computer running
2381 @c Bit fields are written as a general facility but are also controlled
2382 @c by a conditional-compilation flag---which is as of now (21mar91)
2383 @c turned on only by the i960 config of GAS.
2385 @subsubsection Bit Fields
2388 @cindex constants, bit field
2389 You can also define numeric constants as @dfn{bit fields}.
2390 specify two numbers separated by a colon---
2392 @var{mask}:@var{value}
2395 @code{@value{AS}} applies a bitwise @sc{and} between @var{mask} and
2398 The resulting number is then packed
2400 @c this conditional paren in case bit fields turned on elsewhere than 960
2401 (in host-dependent byte order)
2403 into a field whose width depends on which assembler directive has the
2404 bit-field as its argument. Overflow (a result from the bitwise and
2405 requiring more binary digits to represent) is not an error; instead,
2406 more constants are generated, of the specified width, beginning with the
2407 least significant digits.@refill
2409 The directives @code{.byte}, @code{.hword}, @code{.int}, @code{.long},
2410 @code{.short}, and @code{.word} accept bit-field arguments.
2415 @chapter Sections and Relocation
2420 * Secs Background:: Background
2421 * Ld Sections:: Linker Sections
2422 * As Sections:: Assembler Internal Sections
2423 * Sub-Sections:: Sub-Sections
2427 @node Secs Background
2430 Roughly, a section is a range of addresses, with no gaps; all data
2431 ``in'' those addresses is treated the same for some particular purpose.
2432 For example there may be a ``read only'' section.
2434 @cindex linker, and assembler
2435 @cindex assembler, and linker
2436 The linker @code{@value{LD}} reads many object files (partial programs) and
2437 combines their contents to form a runnable program. When @code{@value{AS}}
2438 emits an object file, the partial program is assumed to start at address 0.
2439 @code{@value{LD}} assigns the final addresses for the partial program, so that
2440 different partial programs do not overlap. This is actually an
2441 oversimplification, but it suffices to explain how @code{@value{AS}} uses
2444 @code{@value{LD}} moves blocks of bytes of your program to their run-time
2445 addresses. These blocks slide to their run-time addresses as rigid
2446 units; their length does not change and neither does the order of bytes
2447 within them. Such a rigid unit is called a @emph{section}. Assigning
2448 run-time addresses to sections is called @dfn{relocation}. It includes
2449 the task of adjusting mentions of object-file addresses so they refer to
2450 the proper run-time addresses.
2452 For the H8/300 and H8/500,
2453 and for the Hitachi SH,
2454 @code{@value{AS}} pads sections if needed to
2455 ensure they end on a word (sixteen bit) boundary.
2458 @cindex standard assembler sections
2459 An object file written by @code{@value{AS}} has at least three sections, any
2460 of which may be empty. These are named @dfn{text}, @dfn{data} and
2465 When it generates COFF output,
2467 @code{@value{AS}} can also generate whatever other named sections you specify
2468 using the @samp{.section} directive (@pxref{Section,,@code{.section}}).
2469 If you do not use any directives that place output in the @samp{.text}
2470 or @samp{.data} sections, these sections still exist, but are empty.
2475 When @code{@value{AS}} generates SOM or ELF output for the HPPA,
2477 @code{@value{AS}} can also generate whatever other named sections you
2478 specify using the @samp{.space} and @samp{.subspace} directives. See
2479 @cite{HP9000 Series 800 Assembly Language Reference Manual}
2480 (HP 92432-90001) for details on the @samp{.space} and @samp{.subspace}
2481 assembler directives.
2484 Additionally, @code{@value{AS}} uses different names for the standard
2485 text, data, and bss sections when generating SOM output. Program text
2486 is placed into the @samp{$CODE$} section, data into @samp{$DATA$}, and
2487 BSS into @samp{$BSS$}.
2491 Within the object file, the text section starts at address @code{0}, the
2492 data section follows, and the bss section follows the data section.
2495 When generating either SOM or ELF output files on the HPPA, the text
2496 section starts at address @code{0}, the data section at address
2497 @code{0x4000000}, and the bss section follows the data section.
2500 To let @code{@value{LD}} know which data changes when the sections are
2501 relocated, and how to change that data, @code{@value{AS}} also writes to the
2502 object file details of the relocation needed. To perform relocation
2503 @code{@value{LD}} must know, each time an address in the object
2507 Where in the object file is the beginning of this reference to
2510 How long (in bytes) is this reference?
2512 Which section does the address refer to? What is the numeric value of
2514 (@var{address}) @minus{} (@var{start-address of section})?
2517 Is the reference to an address ``Program-Counter relative''?
2520 @cindex addresses, format of
2521 @cindex section-relative addressing
2522 In fact, every address @code{@value{AS}} ever uses is expressed as
2524 (@var{section}) + (@var{offset into section})
2527 Further, most expressions @code{@value{AS}} computes have this section-relative
2530 (For some object formats, such as SOM for the HPPA, some expressions are
2531 symbol-relative instead.)
2534 In this manual we use the notation @{@var{secname} @var{N}@} to mean ``offset
2535 @var{N} into section @var{secname}.''
2537 Apart from text, data and bss sections you need to know about the
2538 @dfn{absolute} section. When @code{@value{LD}} mixes partial programs,
2539 addresses in the absolute section remain unchanged. For example, address
2540 @code{@{absolute 0@}} is ``relocated'' to run-time address 0 by
2541 @code{@value{LD}}. Although the linker never arranges two partial programs'
2542 data sections with overlapping addresses after linking, @emph{by definition}
2543 their absolute sections must overlap. Address @code{@{absolute@ 239@}} in one
2544 part of a program is always the same address when the program is running as
2545 address @code{@{absolute@ 239@}} in any other part of the program.
2547 The idea of sections is extended to the @dfn{undefined} section. Any
2548 address whose section is unknown at assembly time is by definition
2549 rendered @{undefined @var{U}@}---where @var{U} is filled in later.
2550 Since numbers are always defined, the only way to generate an undefined
2551 address is to mention an undefined symbol. A reference to a named
2552 common block would be such a symbol: its value is unknown at assembly
2553 time so it has section @emph{undefined}.
2555 By analogy the word @emph{section} is used to describe groups of sections in
2556 the linked program. @code{@value{LD}} puts all partial programs' text
2557 sections in contiguous addresses in the linked program. It is
2558 customary to refer to the @emph{text section} of a program, meaning all
2559 the addresses of all partial programs' text sections. Likewise for
2560 data and bss sections.
2562 Some sections are manipulated by @code{@value{LD}}; others are invented for
2563 use of @code{@value{AS}} and have no meaning except during assembly.
2566 @section Linker Sections
2567 @code{@value{LD}} deals with just four kinds of sections, summarized below.
2572 @cindex named sections
2573 @cindex sections, named
2574 @item named sections
2577 @cindex text section
2578 @cindex data section
2582 These sections hold your program. @code{@value{AS}} and @code{@value{LD}} treat them as
2583 separate but equal sections. Anything you can say of one section is
2586 When the program is running, however, it is
2587 customary for the text section to be unalterable. The
2588 text section is often shared among processes: it contains
2589 instructions, constants and the like. The data section of a running
2590 program is usually alterable: for example, C variables would be stored
2591 in the data section.
2596 This section contains zeroed bytes when your program begins running. It
2597 is used to hold uninitialized variables or common storage. The length of
2598 each partial program's bss section is important, but because it starts
2599 out containing zeroed bytes there is no need to store explicit zero
2600 bytes in the object file. The bss section was invented to eliminate
2601 those explicit zeros from object files.
2603 @cindex absolute section
2604 @item absolute section
2605 Address 0 of this section is always ``relocated'' to runtime address 0.
2606 This is useful if you want to refer to an address that @code{@value{LD}} must
2607 not change when relocating. In this sense we speak of absolute
2608 addresses being ``unrelocatable'': they do not change during relocation.
2610 @cindex undefined section
2611 @item undefined section
2612 This ``section'' is a catch-all for address references to objects not in
2613 the preceding sections.
2614 @c FIXME: ref to some other doc on obj-file formats could go here.
2617 @cindex relocation example
2618 An idealized example of three relocatable sections follows.
2620 The example uses the traditional section names @samp{.text} and @samp{.data}.
2622 Memory addresses are on the horizontal axis.
2626 @c END TEXI2ROFF-KILL
2629 partial program # 1: |ttttt|dddd|00|
2636 partial program # 2: |TTT|DDD|000|
2639 +--+---+-----+--+----+---+-----+~~
2640 linked program: | |TTT|ttttt| |dddd|DDD|00000|
2641 +--+---+-----+--+----+---+-----+~~
2643 addresses: 0 @dots{}
2650 \line{\it Partial program \#1: \hfil}
2651 \line{\ibox{2.5cm}{\tt text}\ibox{2cm}{\tt data}\ibox{1cm}{\tt bss}\hfil}
2652 \line{\boxit{2.5cm}{\tt ttttt}\boxit{2cm}{\tt dddd}\boxit{1cm}{\tt 00}\hfil}
2654 \line{\it Partial program \#2: \hfil}
2655 \line{\ibox{1cm}{\tt text}\ibox{1.5cm}{\tt data}\ibox{1cm}{\tt bss}\hfil}
2656 \line{\boxit{1cm}{\tt TTT}\boxit{1.5cm}{\tt DDDD}\boxit{1cm}{\tt 000}\hfil}
2658 \line{\it linked program: \hfil}
2659 \line{\ibox{.5cm}{}\ibox{1cm}{\tt text}\ibox{2.5cm}{}\ibox{.75cm}{}\ibox{2cm}{\tt data}\ibox{1.5cm}{}\ibox{2cm}{\tt bss}\hfil}
2660 \line{\boxit{.5cm}{}\boxit{1cm}{\tt TTT}\boxit{2.5cm}{\tt
2661 ttttt}\boxit{.75cm}{}\boxit{2cm}{\tt dddd}\boxit{1.5cm}{\tt
2662 DDDD}\boxit{2cm}{\tt 00000}\ \dots\hfil}
2664 \line{\it addresses: \hfil}
2668 @c END TEXI2ROFF-KILL
2671 @section Assembler Internal Sections
2673 @cindex internal assembler sections
2674 @cindex sections in messages, internal
2675 These sections are meant only for the internal use of @code{@value{AS}}. They
2676 have no meaning at run-time. You do not really need to know about these
2677 sections for most purposes; but they can be mentioned in @code{@value{AS}}
2678 warning messages, so it might be helpful to have an idea of their
2679 meanings to @code{@value{AS}}. These sections are used to permit the
2680 value of every expression in your assembly language program to be a
2681 section-relative address.
2684 @cindex assembler internal logic error
2685 @item ASSEMBLER-INTERNAL-LOGIC-ERROR!
2686 An internal assembler logic error has been found. This means there is a
2687 bug in the assembler.
2689 @cindex expr (internal section)
2691 The assembler stores complex expression internally as combinations of
2692 symbols. When it needs to represent an expression as a symbol, it puts
2693 it in the expr section.
2695 @c FIXME item transfer[t] vector preload
2696 @c FIXME item transfer[t] vector postload
2697 @c FIXME item register
2701 @section Sub-Sections
2703 @cindex numbered subsections
2704 @cindex grouping data
2710 fall into two sections: text and data.
2712 You may have separate groups of
2714 data in named sections
2718 data in named sections
2724 that you want to end up near to each other in the object file, even though they
2725 are not contiguous in the assembler source. @code{@value{AS}} allows you to
2726 use @dfn{subsections} for this purpose. Within each section, there can be
2727 numbered subsections with values from 0 to 8192. Objects assembled into the
2728 same subsection go into the object file together with other objects in the same
2729 subsection. For example, a compiler might want to store constants in the text
2730 section, but might not want to have them interspersed with the program being
2731 assembled. In this case, the compiler could issue a @samp{.text 0} before each
2732 section of code being output, and a @samp{.text 1} before each group of
2733 constants being output.
2735 Subsections are optional. If you do not use subsections, everything
2736 goes in subsection number zero.
2739 Each subsection is zero-padded up to a multiple of four bytes.
2740 (Subsections may be padded a different amount on different flavors
2741 of @code{@value{AS}}.)
2745 On the H8/300 and H8/500 platforms, each subsection is zero-padded to a word
2746 boundary (two bytes).
2747 The same is true on the Hitachi SH.
2750 @c FIXME section padding (alignment)?
2751 @c Rich Pixley says padding here depends on target obj code format; that
2752 @c doesn't seem particularly useful to say without further elaboration,
2753 @c so for now I say nothing about it. If this is a generic BFD issue,
2754 @c these paragraphs might need to vanish from this manual, and be
2755 @c discussed in BFD chapter of binutils (or some such).
2758 On the AMD 29K family, no particular padding is added to section or
2759 subsection sizes; @value{AS} forces no alignment on this platform.
2763 Subsections appear in your object file in numeric order, lowest numbered
2764 to highest. (All this to be compatible with other people's assemblers.)
2765 The object file contains no representation of subsections; @code{@value{LD}} and
2766 other programs that manipulate object files see no trace of them.
2767 They just see all your text subsections as a text section, and all your
2768 data subsections as a data section.
2770 To specify which subsection you want subsequent statements assembled
2771 into, use a numeric argument to specify it, in a @samp{.text
2772 @var{expression}} or a @samp{.data @var{expression}} statement.
2775 When generating COFF output, you
2780 can also use an extra subsection
2781 argument with arbitrary named sections: @samp{.section @var{name},
2784 @var{Expression} should be an absolute expression.
2785 (@xref{Expressions}.) If you just say @samp{.text} then @samp{.text 0}
2786 is assumed. Likewise @samp{.data} means @samp{.data 0}. Assembly
2787 begins in @code{text 0}. For instance:
2789 .text 0 # The default subsection is text 0 anyway.
2790 .ascii "This lives in the first text subsection. *"
2792 .ascii "But this lives in the second text subsection."
2794 .ascii "This lives in the data section,"
2795 .ascii "in the first data subsection."
2797 .ascii "This lives in the first text section,"
2798 .ascii "immediately following the asterisk (*)."
2801 Each section has a @dfn{location counter} incremented by one for every byte
2802 assembled into that section. Because subsections are merely a convenience
2803 restricted to @code{@value{AS}} there is no concept of a subsection location
2804 counter. There is no way to directly manipulate a location counter---but the
2805 @code{.align} directive changes it, and any label definition captures its
2806 current value. The location counter of the section where statements are being
2807 assembled is said to be the @dfn{active} location counter.
2810 @section bss Section
2813 @cindex common variable storage
2814 The bss section is used for local common variable storage.
2815 You may allocate address space in the bss section, but you may
2816 not dictate data to load into it before your program executes. When
2817 your program starts running, all the contents of the bss
2818 section are zeroed bytes.
2820 The @code{.lcomm} pseudo-op defines a symbol in the bss section; see
2821 @ref{Lcomm,,@code{.lcomm}}.
2823 The @code{.comm} pseudo-op may be used to declare a common symbol, which is
2824 another form of uninitialized symbol; see @xref{Comm,,@code{.comm}}.
2827 When assembling for a target which supports multiple sections, such as ELF or
2828 COFF, you may switch into the @code{.bss} section and define symbols as usual;
2829 see @ref{Section,,@code{.section}}. You may only assemble zero values into the
2830 section. Typically the section will only contain symbol definitions and
2831 @code{.skip} directives (@pxref{Skip,,@code{.skip}}).
2838 Symbols are a central concept: the programmer uses symbols to name
2839 things, the linker uses symbols to link, and the debugger uses symbols
2843 @cindex debuggers, and symbol order
2844 @emph{Warning:} @code{@value{AS}} does not place symbols in the object file in
2845 the same order they were declared. This may break some debuggers.
2850 * Setting Symbols:: Giving Symbols Other Values
2851 * Symbol Names:: Symbol Names
2852 * Dot:: The Special Dot Symbol
2853 * Symbol Attributes:: Symbol Attributes
2860 A @dfn{label} is written as a symbol immediately followed by a colon
2861 @samp{:}. The symbol then represents the current value of the
2862 active location counter, and is, for example, a suitable instruction
2863 operand. You are warned if you use the same symbol to represent two
2864 different locations: the first definition overrides any other
2868 On the HPPA, the usual form for a label need not be immediately followed by a
2869 colon, but instead must start in column zero. Only one label may be defined on
2870 a single line. To work around this, the HPPA version of @code{@value{AS}} also
2871 provides a special directive @code{.label} for defining labels more flexibly.
2874 @node Setting Symbols
2875 @section Giving Symbols Other Values
2877 @cindex assigning values to symbols
2878 @cindex symbol values, assigning
2879 A symbol can be given an arbitrary value by writing a symbol, followed
2880 by an equals sign @samp{=}, followed by an expression
2881 (@pxref{Expressions}). This is equivalent to using the @code{.set}
2882 directive. @xref{Set,,@code{.set}}.
2885 @section Symbol Names
2887 @cindex symbol names
2888 @cindex names, symbol
2889 @ifclear SPECIAL-SYMS
2890 Symbol names begin with a letter or with one of @samp{._}. On most
2891 machines, you can also use @code{$} in symbol names; exceptions are
2892 noted in @ref{Machine Dependencies}. That character may be followed by any
2893 string of digits, letters, dollar signs (unless otherwise noted in
2894 @ref{Machine Dependencies}), and underscores.
2897 For the AMD 29K family, @samp{?} is also allowed in the
2898 body of a symbol name, though not at its beginning.
2903 Symbol names begin with a letter or with one of @samp{._}. On the
2905 H8/500, you can also use @code{$} in symbol names. That character may
2906 be followed by any string of digits, letters, dollar signs (save on the
2907 H8/300), and underscores.
2911 Case of letters is significant: @code{foo} is a different symbol name
2914 Each symbol has exactly one name. Each name in an assembly language program
2915 refers to exactly one symbol. You may use that symbol name any number of times
2918 @subheading Local Symbol Names
2920 @cindex local symbol names
2921 @cindex symbol names, local
2922 @cindex temporary symbol names
2923 @cindex symbol names, temporary
2924 Local symbols help compilers and programmers use names temporarily.
2925 They create symbols which are guaranteed to be unique over the entire scope of
2926 the input source code and which can be referred to by a simple notation.
2927 To define a local symbol, write a label of the form @samp{@b{N}:} (where @b{N}
2928 represents any positive integer). To refer to the most recent previous
2929 definition of that symbol write @samp{@b{N}b}, using the same number as when
2930 you defined the label. To refer to the next definition of a local label, write
2931 @samp{@b{N}f}--- The @samp{b} stands for``backwards'' and the @samp{f} stands
2934 There is no restriction on how you can use these labels, and you can reuse them
2935 too. So that it is possible to repeatedly define the same local label (using
2936 the same number @samp{@b{N}}), although you can only refer to the most recently
2937 defined local label of that number (for a backwards reference) or the next
2938 definition of a specific local label for a forward reference. It is also worth
2939 noting that the first 10 local labels (@samp{@b{0:}}@dots{}@samp{@b{9:}}) are
2940 implemented in a slightly more efficient manner than the others.
2951 Which is the equivalent of:
2954 label_1: branch label_3
2955 label_2: branch label_1
2956 label_3: branch label_4
2957 label_4: branch label_3
2960 Local symbol names are only a notational device. They are immediately
2961 transformed into more conventional symbol names before the assembler uses them.
2962 The symbol names stored in the symbol table, appearing in error messages and
2963 optionally emitted to the object file. The names are constructed using these
2968 All local labels begin with @samp{L}. Normally both @code{@value{AS}} and
2969 @code{@value{LD}} forget symbols that start with @samp{L}. These labels are
2970 used for symbols you are never intended to see. If you use the
2971 @samp{-L} option then @code{@value{AS}} retains these symbols in the
2972 object file. If you also instruct @code{@value{LD}} to retain these symbols,
2973 you may use them in debugging.
2976 This is the number that was used in the local label definition. So if the
2977 label is written @samp{55:} then the number is @samp{55}.
2980 This unusual character is included so you do not accidentally invent a symbol
2981 of the same name. The character has ASCII value of @samp{\002} (control-B).
2983 @item @emph{ordinal number}
2984 This is a serial number to keep the labels distinct. The first definition of
2985 @samp{0:} gets the number @samp{1}. The 15th definition of @samp{0:} gets the
2986 number @samp{15}, and so on. Likewise the first definition of @samp{1:} gets
2987 the number @samp{1} and its 15th defintion gets @samp{15} as well.
2990 So for example, the first @code{1:} is named @code{L1@kbd{C-B}1}, the 44th
2991 @code{3:} is named @code{L3@kbd{C-B}44}.
2993 @subheading Dollar Local Labels
2994 @cindex dollar local symbols
2996 @code{@value{AS}} also supports an even more local form of local labels called
2997 dollar labels. These labels go out of scope (ie they become undefined) as soon
2998 as a non-local label is defined. Thus they remain valid for only a small
2999 region of the input source code. Normal local labels, by contrast, remain in
3000 scope for the entire file, or until they are redefined by another occurrence of
3001 the same local label.
3003 Dollar labels are defined in exactly the same way as ordinary local labels,
3004 except that instead of being terminated by a colon, they are terminated by a
3005 dollar sign. eg @samp{@b{55$}}.
3007 They can also be distinguished from ordinary local labels by their transformed
3008 name which uses ASCII character @samp{\001} (control-A) as the magic character
3009 to distinguish them from ordinary labels. Thus the 5th defintion of @samp{6$}
3010 is named @samp{L6@kbd{C-A}5}.
3013 @section The Special Dot Symbol
3015 @cindex dot (symbol)
3016 @cindex @code{.} (symbol)
3017 @cindex current address
3018 @cindex location counter
3019 The special symbol @samp{.} refers to the current address that
3020 @code{@value{AS}} is assembling into. Thus, the expression @samp{melvin:
3021 .long .} defines @code{melvin} to contain its own address.
3022 Assigning a value to @code{.} is treated the same as a @code{.org}
3023 directive. Thus, the expression @samp{.=.+4} is the same as saying
3024 @ifclear no-space-dir
3033 @node Symbol Attributes
3034 @section Symbol Attributes
3036 @cindex symbol attributes
3037 @cindex attributes, symbol
3038 Every symbol has, as well as its name, the attributes ``Value'' and
3039 ``Type''. Depending on output format, symbols can also have auxiliary
3042 The detailed definitions are in @file{a.out.h}.
3045 If you use a symbol without defining it, @code{@value{AS}} assumes zero for
3046 all these attributes, and probably won't warn you. This makes the
3047 symbol an externally defined symbol, which is generally what you
3051 * Symbol Value:: Value
3052 * Symbol Type:: Type
3055 * a.out Symbols:: Symbol Attributes: @code{a.out}
3059 * a.out Symbols:: Symbol Attributes: @code{a.out}
3062 * a.out Symbols:: Symbol Attributes: @code{a.out}, @code{b.out}
3067 * COFF Symbols:: Symbol Attributes for COFF
3070 * SOM Symbols:: Symbol Attributes for SOM
3077 @cindex value of a symbol
3078 @cindex symbol value
3079 The value of a symbol is (usually) 32 bits. For a symbol which labels a
3080 location in the text, data, bss or absolute sections the value is the
3081 number of addresses from the start of that section to the label.
3082 Naturally for text, data and bss sections the value of a symbol changes
3083 as @code{@value{LD}} changes section base addresses during linking. Absolute
3084 symbols' values do not change during linking: that is why they are
3087 The value of an undefined symbol is treated in a special way. If it is
3088 0 then the symbol is not defined in this assembler source file, and
3089 @code{@value{LD}} tries to determine its value from other files linked into the
3090 same program. You make this kind of symbol simply by mentioning a symbol
3091 name without defining it. A non-zero value represents a @code{.comm}
3092 common declaration. The value is how much common storage to reserve, in
3093 bytes (addresses). The symbol refers to the first address of the
3099 @cindex type of a symbol
3101 The type attribute of a symbol contains relocation (section)
3102 information, any flag settings indicating that a symbol is external, and
3103 (optionally), other information for linkers and debuggers. The exact
3104 format depends on the object-code output format in use.
3109 @c The following avoids a "widow" subsection title. @group would be
3110 @c better if it were available outside examples.
3113 @subsection Symbol Attributes: @code{a.out}, @code{b.out}
3115 @cindex @code{b.out} symbol attributes
3116 @cindex symbol attributes, @code{b.out}
3117 These symbol attributes appear only when @code{@value{AS}} is configured for
3118 one of the Berkeley-descended object output formats---@code{a.out} or
3124 @subsection Symbol Attributes: @code{a.out}
3126 @cindex @code{a.out} symbol attributes
3127 @cindex symbol attributes, @code{a.out}
3133 @subsection Symbol Attributes: @code{a.out}
3135 @cindex @code{a.out} symbol attributes
3136 @cindex symbol attributes, @code{a.out}
3140 * Symbol Desc:: Descriptor
3141 * Symbol Other:: Other
3145 @subsubsection Descriptor
3147 @cindex descriptor, of @code{a.out} symbol
3148 This is an arbitrary 16-bit value. You may establish a symbol's
3149 descriptor value by using a @code{.desc} statement
3150 (@pxref{Desc,,@code{.desc}}). A descriptor value means nothing to
3154 @subsubsection Other
3156 @cindex other attribute, of @code{a.out} symbol
3157 This is an arbitrary 8-bit value. It means nothing to @code{@value{AS}}.
3162 @subsection Symbol Attributes for COFF
3164 @cindex COFF symbol attributes
3165 @cindex symbol attributes, COFF
3167 The COFF format supports a multitude of auxiliary symbol attributes;
3168 like the primary symbol attributes, they are set between @code{.def} and
3169 @code{.endef} directives.
3171 @subsubsection Primary Attributes
3173 @cindex primary attributes, COFF symbols
3174 The symbol name is set with @code{.def}; the value and type,
3175 respectively, with @code{.val} and @code{.type}.
3177 @subsubsection Auxiliary Attributes
3179 @cindex auxiliary attributes, COFF symbols
3180 The @code{@value{AS}} directives @code{.dim}, @code{.line}, @code{.scl},
3181 @code{.size}, and @code{.tag} can generate auxiliary symbol table
3182 information for COFF.
3187 @subsection Symbol Attributes for SOM
3189 @cindex SOM symbol attributes
3190 @cindex symbol attributes, SOM
3192 The SOM format for the HPPA supports a multitude of symbol attributes set with
3193 the @code{.EXPORT} and @code{.IMPORT} directives.
3195 The attributes are described in @cite{HP9000 Series 800 Assembly
3196 Language Reference Manual} (HP 92432-90001) under the @code{IMPORT} and
3197 @code{EXPORT} assembler directive documentation.
3201 @chapter Expressions
3205 @cindex numeric values
3206 An @dfn{expression} specifies an address or numeric value.
3207 Whitespace may precede and/or follow an expression.
3209 The result of an expression must be an absolute number, or else an offset into
3210 a particular section. If an expression is not absolute, and there is not
3211 enough information when @code{@value{AS}} sees the expression to know its
3212 section, a second pass over the source program might be necessary to interpret
3213 the expression---but the second pass is currently not implemented.
3214 @code{@value{AS}} aborts with an error message in this situation.
3217 * Empty Exprs:: Empty Expressions
3218 * Integer Exprs:: Integer Expressions
3222 @section Empty Expressions
3224 @cindex empty expressions
3225 @cindex expressions, empty
3226 An empty expression has no value: it is just whitespace or null.
3227 Wherever an absolute expression is required, you may omit the
3228 expression, and @code{@value{AS}} assumes a value of (absolute) 0. This
3229 is compatible with other assemblers.
3232 @section Integer Expressions
3234 @cindex integer expressions
3235 @cindex expressions, integer
3236 An @dfn{integer expression} is one or more @emph{arguments} delimited
3237 by @emph{operators}.
3240 * Arguments:: Arguments
3241 * Operators:: Operators
3242 * Prefix Ops:: Prefix Operators
3243 * Infix Ops:: Infix Operators
3247 @subsection Arguments
3249 @cindex expression arguments
3250 @cindex arguments in expressions
3251 @cindex operands in expressions
3252 @cindex arithmetic operands
3253 @dfn{Arguments} are symbols, numbers or subexpressions. In other
3254 contexts arguments are sometimes called ``arithmetic operands''. In
3255 this manual, to avoid confusing them with the ``instruction operands'' of
3256 the machine language, we use the term ``argument'' to refer to parts of
3257 expressions only, reserving the word ``operand'' to refer only to machine
3258 instruction operands.
3260 Symbols are evaluated to yield @{@var{section} @var{NNN}@} where
3261 @var{section} is one of text, data, bss, absolute,
3262 or undefined. @var{NNN} is a signed, 2's complement 32 bit
3265 Numbers are usually integers.
3267 A number can be a flonum or bignum. In this case, you are warned
3268 that only the low order 32 bits are used, and @code{@value{AS}} pretends
3269 these 32 bits are an integer. You may write integer-manipulating
3270 instructions that act on exotic constants, compatible with other
3273 @cindex subexpressions
3274 Subexpressions are a left parenthesis @samp{(} followed by an integer
3275 expression, followed by a right parenthesis @samp{)}; or a prefix
3276 operator followed by an argument.
3279 @subsection Operators
3281 @cindex operators, in expressions
3282 @cindex arithmetic functions
3283 @cindex functions, in expressions
3284 @dfn{Operators} are arithmetic functions, like @code{+} or @code{%}. Prefix
3285 operators are followed by an argument. Infix operators appear
3286 between their arguments. Operators may be preceded and/or followed by
3290 @subsection Prefix Operator
3292 @cindex prefix operators
3293 @code{@value{AS}} has the following @dfn{prefix operators}. They each take
3294 one argument, which must be absolute.
3296 @c the tex/end tex stuff surrounding this small table is meant to make
3297 @c it align, on the printed page, with the similar table in the next
3298 @c section (which is inside an enumerate).
3300 \global\advance\leftskip by \itemindent
3305 @dfn{Negation}. Two's complement negation.
3307 @dfn{Complementation}. Bitwise not.
3311 \global\advance\leftskip by -\itemindent
3315 @subsection Infix Operators
3317 @cindex infix operators
3318 @cindex operators, permitted arguments
3319 @dfn{Infix operators} take two arguments, one on either side. Operators
3320 have precedence, but operations with equal precedence are performed left
3321 to right. Apart from @code{+} or @code{-}, both arguments must be
3322 absolute, and the result is absolute.
3325 @cindex operator precedence
3326 @cindex precedence of operators
3333 @dfn{Multiplication}.
3336 @dfn{Division}. Truncation is the same as the C operator @samp{/}
3343 @dfn{Shift Left}. Same as the C operator @samp{<<}.
3347 @dfn{Shift Right}. Same as the C operator @samp{>>}.
3351 Intermediate precedence
3356 @dfn{Bitwise Inclusive Or}.
3362 @dfn{Bitwise Exclusive Or}.
3365 @dfn{Bitwise Or Not}.
3372 @cindex addition, permitted arguments
3373 @cindex plus, permitted arguments
3374 @cindex arguments for addition
3376 @dfn{Addition}. If either argument is absolute, the result has the section of
3377 the other argument. You may not add together arguments from different
3380 @cindex subtraction, permitted arguments
3381 @cindex minus, permitted arguments
3382 @cindex arguments for subtraction
3384 @dfn{Subtraction}. If the right argument is absolute, the
3385 result has the section of the left argument.
3386 If both arguments are in the same section, the result is absolute.
3387 You may not subtract arguments from different sections.
3388 @c FIXME is there still something useful to say about undefined - undefined ?
3390 @cindex comparison expressions
3391 @cindex expressions, comparison
3395 @dfn{Is Not Equal To}
3399 @dfn{Is Greater Than}
3401 @dfn{Is Greater Than Or Equal To}
3403 @dfn{Is Less Than Or Equal To}
3405 The comparison operators can be used as infix operators. A true results has a
3406 value of -1 whereas a false result has a value of 0. Note, these operators
3407 perform signed comparisons.
3410 @item Lowest Precedence
3419 These two logical operations can be used to combine the results of sub
3420 expressions. Note, unlike the comparison operators a true result returns a
3421 value of 1 but a false results does still return 0. Also note that the logical
3422 or operator has a slightly lower precedence than logical and.
3427 In short, it's only meaningful to add or subtract the @emph{offsets} in an
3428 address; you can only have a defined section in one of the two arguments.
3431 @chapter Assembler Directives
3433 @cindex directives, machine independent
3434 @cindex pseudo-ops, machine independent
3435 @cindex machine independent directives
3436 All assembler directives have names that begin with a period (@samp{.}).
3437 The rest of the name is letters, usually in lower case.
3439 This chapter discusses directives that are available regardless of the
3440 target machine configuration for the @sc{gnu} assembler.
3442 Some machine configurations provide additional directives.
3443 @xref{Machine Dependencies}.
3446 @ifset machine-directives
3447 @xref{Machine Dependencies} for additional directives.
3452 * Abort:: @code{.abort}
3454 * ABORT:: @code{.ABORT}
3457 * Align:: @code{.align @var{abs-expr} , @var{abs-expr}}
3458 * Ascii:: @code{.ascii "@var{string}"}@dots{}
3459 * Asciz:: @code{.asciz "@var{string}"}@dots{}
3460 * Balign:: @code{.balign @var{abs-expr} , @var{abs-expr}}
3461 * Byte:: @code{.byte @var{expressions}}
3462 * Comm:: @code{.comm @var{symbol} , @var{length} }
3463 * Data:: @code{.data @var{subsection}}
3465 * Def:: @code{.def @var{name}}
3468 * Desc:: @code{.desc @var{symbol}, @var{abs-expression}}
3474 * Double:: @code{.double @var{flonums}}
3475 * Eject:: @code{.eject}
3476 * Else:: @code{.else}
3477 * Elseif:: @code{.elseif}
3480 * Endef:: @code{.endef}
3483 * Endfunc:: @code{.endfunc}
3484 * Endif:: @code{.endif}
3485 * Equ:: @code{.equ @var{symbol}, @var{expression}}
3486 * Equiv:: @code{.equiv @var{symbol}, @var{expression}}
3488 * Exitm:: @code{.exitm}
3489 * Extern:: @code{.extern}
3490 * Fail:: @code{.fail}
3491 @ifclear no-file-dir
3492 * File:: @code{.file @var{string}}
3495 * Fill:: @code{.fill @var{repeat} , @var{size} , @var{value}}
3496 * Float:: @code{.float @var{flonums}}
3497 * Func:: @code{.func}
3498 * Global:: @code{.global @var{symbol}}, @code{.globl @var{symbol}}
3500 * Hidden:: @code{.hidden @var{names}}
3503 * hword:: @code{.hword @var{expressions}}
3504 * Ident:: @code{.ident}
3505 * If:: @code{.if @var{absolute expression}}
3506 * Incbin:: @code{.incbin "@var{file}"[,@var{skip}[,@var{count}]]}
3507 * Include:: @code{.include "@var{file}"}
3508 * Int:: @code{.int @var{expressions}}
3510 * Internal:: @code{.internal @var{names}}
3513 * Irp:: @code{.irp @var{symbol},@var{values}}@dots{}
3514 * Irpc:: @code{.irpc @var{symbol},@var{values}}@dots{}
3515 * Lcomm:: @code{.lcomm @var{symbol} , @var{length}}
3516 * Lflags:: @code{.lflags}
3517 @ifclear no-line-dir
3518 * Line:: @code{.line @var{line-number}}
3521 * Ln:: @code{.ln @var{line-number}}
3522 * Linkonce:: @code{.linkonce [@var{type}]}
3523 * List:: @code{.list}
3524 * Long:: @code{.long @var{expressions}}
3526 * Lsym:: @code{.lsym @var{symbol}, @var{expression}}
3529 * Macro:: @code{.macro @var{name} @var{args}}@dots{}
3530 * MRI:: @code{.mri @var{val}}
3531 * Nolist:: @code{.nolist}
3532 * Octa:: @code{.octa @var{bignums}}
3533 * Org:: @code{.org @var{new-lc} , @var{fill}}
3534 * P2align:: @code{.p2align @var{abs-expr} , @var{abs-expr}}
3536 * PopSection:: @code{.popsection}
3537 * Previous:: @code{.previous}
3540 * Print:: @code{.print @var{string}}
3542 * Protected:: @code{.protected @var{names}}
3545 * Psize:: @code{.psize @var{lines}, @var{columns}}
3546 * Purgem:: @code{.purgem @var{name}}
3548 * PushSection:: @code{.pushsection @var{name}}
3551 * Quad:: @code{.quad @var{bignums}}
3552 * Rept:: @code{.rept @var{count}}
3553 * Sbttl:: @code{.sbttl "@var{subheading}"}
3555 * Scl:: @code{.scl @var{class}}
3556 * Section:: @code{.section @var{name}, @var{subsection}}
3559 * Set:: @code{.set @var{symbol}, @var{expression}}
3560 * Short:: @code{.short @var{expressions}}
3561 * Single:: @code{.single @var{flonums}}
3562 * Size:: @code{.size [@var{name} , @var{expression}]}
3563 * Skip:: @code{.skip @var{size} , @var{fill}}
3564 * Sleb128:: @code{.sleb128 @var{expressions}}
3565 * Space:: @code{.space @var{size} , @var{fill}}
3567 * Stab:: @code{.stabd, .stabn, .stabs}
3570 * String:: @code{.string "@var{str}"}
3571 * Struct:: @code{.struct @var{expression}}
3573 * SubSection:: @code{.subsection}
3574 * Symver:: @code{.symver @var{name},@var{name2@@nodename}}
3578 * Tag:: @code{.tag @var{structname}}
3581 * Text:: @code{.text @var{subsection}}
3582 * Title:: @code{.title "@var{heading}"}
3583 * Type:: @code{.type <@var{int} | @var{name} , @var{type description}>}
3584 * Uleb128:: @code{.uleb128 @var{expressions}}
3586 * Val:: @code{.val @var{addr}}
3590 * Version:: @code{.version "@var{string}"}
3591 * VTableEntry:: @code{.vtable_entry @var{table}, @var{offset}}
3592 * VTableInherit:: @code{.vtable_inherit @var{child}, @var{parent}}
3593 * Weak:: @code{.weak @var{names}}
3596 * Word:: @code{.word @var{expressions}}
3597 * Deprecated:: Deprecated Directives
3601 @section @code{.abort}
3603 @cindex @code{abort} directive
3604 @cindex stopping the assembly
3605 This directive stops the assembly immediately. It is for
3606 compatibility with other assemblers. The original idea was that the
3607 assembly language source would be piped into the assembler. If the sender
3608 of the source quit, it could use this directive tells @code{@value{AS}} to
3609 quit also. One day @code{.abort} will not be supported.
3613 @section @code{.ABORT}
3615 @cindex @code{ABORT} directive
3616 When producing COFF output, @code{@value{AS}} accepts this directive as a
3617 synonym for @samp{.abort}.
3620 When producing @code{b.out} output, @code{@value{AS}} accepts this directive,
3626 @section @code{.align @var{abs-expr}, @var{abs-expr}, @var{abs-expr}}
3628 @cindex padding the location counter
3629 @cindex @code{align} directive
3630 Pad the location counter (in the current subsection) to a particular storage
3631 boundary. The first expression (which must be absolute) is the alignment
3632 required, as described below.
3634 The second expression (also absolute) gives the fill value to be stored in the
3635 padding bytes. It (and the comma) may be omitted. If it is omitted, the
3636 padding bytes are normally zero. However, on some systems, if the section is
3637 marked as containing code and the fill value is omitted, the space is filled
3638 with no-op instructions.
3640 The third expression is also absolute, and is also optional. If it is present,
3641 it is the maximum number of bytes that should be skipped by this alignment
3642 directive. If doing the alignment would require skipping more bytes than the
3643 specified maximum, then the alignment is not done at all. You can omit the
3644 fill value (the second argument) entirely by simply using two commas after the
3645 required alignment; this can be useful if you want the alignment to be filled
3646 with no-op instructions when appropriate.
3648 The way the required alignment is specified varies from system to system.
3649 For the a29k, hppa, m68k, m88k, w65, sparc, and Hitachi SH, and i386 using ELF
3651 the first expression is the
3652 alignment request in bytes. For example @samp{.align 8} advances
3653 the location counter until it is a multiple of 8. If the location counter
3654 is already a multiple of 8, no change is needed.
3656 For other systems, including the i386 using a.out format, and the arm and
3657 strongarm, it is the
3658 number of low-order zero bits the location counter must have after
3659 advancement. For example @samp{.align 3} advances the location
3660 counter until it a multiple of 8. If the location counter is already a
3661 multiple of 8, no change is needed.
3663 This inconsistency is due to the different behaviors of the various
3664 native assemblers for these systems which GAS must emulate.
3665 GAS also provides @code{.balign} and @code{.p2align} directives,
3666 described later, which have a consistent behavior across all
3667 architectures (but are specific to GAS).
3670 @section @code{.ascii "@var{string}"}@dots{}
3672 @cindex @code{ascii} directive
3673 @cindex string literals
3674 @code{.ascii} expects zero or more string literals (@pxref{Strings})
3675 separated by commas. It assembles each string (with no automatic
3676 trailing zero byte) into consecutive addresses.
3679 @section @code{.asciz "@var{string}"}@dots{}
3681 @cindex @code{asciz} directive
3682 @cindex zero-terminated strings
3683 @cindex null-terminated strings
3684 @code{.asciz} is just like @code{.ascii}, but each string is followed by
3685 a zero byte. The ``z'' in @samp{.asciz} stands for ``zero''.
3688 @section @code{.balign[wl] @var{abs-expr}, @var{abs-expr}, @var{abs-expr}}
3690 @cindex padding the location counter given number of bytes
3691 @cindex @code{balign} directive
3692 Pad the location counter (in the current subsection) to a particular
3693 storage boundary. The first expression (which must be absolute) is the
3694 alignment request in bytes. For example @samp{.balign 8} advances
3695 the location counter until it is a multiple of 8. If the location counter
3696 is already a multiple of 8, no change is needed.
3698 The second expression (also absolute) gives the fill value to be stored in the
3699 padding bytes. It (and the comma) may be omitted. If it is omitted, the
3700 padding bytes are normally zero. However, on some systems, if the section is
3701 marked as containing code and the fill value is omitted, the space is filled
3702 with no-op instructions.
3704 The third expression is also absolute, and is also optional. If it is present,
3705 it is the maximum number of bytes that should be skipped by this alignment
3706 directive. If doing the alignment would require skipping more bytes than the
3707 specified maximum, then the alignment is not done at all. You can omit the
3708 fill value (the second argument) entirely by simply using two commas after the
3709 required alignment; this can be useful if you want the alignment to be filled
3710 with no-op instructions when appropriate.
3712 @cindex @code{balignw} directive
3713 @cindex @code{balignl} directive
3714 The @code{.balignw} and @code{.balignl} directives are variants of the
3715 @code{.balign} directive. The @code{.balignw} directive treats the fill
3716 pattern as a two byte word value. The @code{.balignl} directives treats the
3717 fill pattern as a four byte longword value. For example, @code{.balignw
3718 4,0x368d} will align to a multiple of 4. If it skips two bytes, they will be
3719 filled in with the value 0x368d (the exact placement of the bytes depends upon
3720 the endianness of the processor). If it skips 1 or 3 bytes, the fill value is
3724 @section @code{.byte @var{expressions}}
3726 @cindex @code{byte} directive
3727 @cindex integers, one byte
3728 @code{.byte} expects zero or more expressions, separated by commas.
3729 Each expression is assembled into the next byte.
3732 @section @code{.comm @var{symbol} , @var{length} }
3734 @cindex @code{comm} directive
3735 @cindex symbol, common
3736 @code{.comm} declares a common symbol named @var{symbol}. When linking, a
3737 common symbol in one object file may be merged with a defined or common symbol
3738 of the same name in another object file. If @code{@value{LD}} does not see a
3739 definition for the symbol--just one or more common symbols--then it will
3740 allocate @var{length} bytes of uninitialized memory. @var{length} must be an
3741 absolute expression. If @code{@value{LD}} sees multiple common symbols with
3742 the same name, and they do not all have the same size, it will allocate space
3743 using the largest size.
3746 When using ELF, the @code{.comm} directive takes an optional third argument.
3747 This is the desired alignment of the symbol, specified as a byte boundary (for
3748 example, an alignment of 16 means that the least significant 4 bits of the
3749 address should be zero). The alignment must be an absolute expression, and it
3750 must be a power of two. If @code{@value{LD}} allocates uninitialized memory
3751 for the common symbol, it will use the alignment when placing the symbol. If
3752 no alignment is specified, @code{@value{AS}} will set the alignment to the
3753 largest power of two less than or equal to the size of the symbol, up to a
3758 The syntax for @code{.comm} differs slightly on the HPPA. The syntax is
3759 @samp{@var{symbol} .comm, @var{length}}; @var{symbol} is optional.
3763 @section @code{.data @var{subsection}}
3765 @cindex @code{data} directive
3766 @code{.data} tells @code{@value{AS}} to assemble the following statements onto the
3767 end of the data subsection numbered @var{subsection} (which is an
3768 absolute expression). If @var{subsection} is omitted, it defaults
3773 @section @code{.def @var{name}}
3775 @cindex @code{def} directive
3776 @cindex COFF symbols, debugging
3777 @cindex debugging COFF symbols
3778 Begin defining debugging information for a symbol @var{name}; the
3779 definition extends until the @code{.endef} directive is encountered.
3782 This directive is only observed when @code{@value{AS}} is configured for COFF
3783 format output; when producing @code{b.out}, @samp{.def} is recognized,
3790 @section @code{.desc @var{symbol}, @var{abs-expression}}
3792 @cindex @code{desc} directive
3793 @cindex COFF symbol descriptor
3794 @cindex symbol descriptor, COFF
3795 This directive sets the descriptor of the symbol (@pxref{Symbol Attributes})
3796 to the low 16 bits of an absolute expression.
3799 The @samp{.desc} directive is not available when @code{@value{AS}} is
3800 configured for COFF output; it is only for @code{a.out} or @code{b.out}
3801 object format. For the sake of compatibility, @code{@value{AS}} accepts
3802 it, but produces no output, when configured for COFF.
3808 @section @code{.dim}
3810 @cindex @code{dim} directive
3811 @cindex COFF auxiliary symbol information
3812 @cindex auxiliary symbol information, COFF
3813 This directive is generated by compilers to include auxiliary debugging
3814 information in the symbol table. It is only permitted inside
3815 @code{.def}/@code{.endef} pairs.
3818 @samp{.dim} is only meaningful when generating COFF format output; when
3819 @code{@value{AS}} is generating @code{b.out}, it accepts this directive but
3825 @section @code{.double @var{flonums}}
3827 @cindex @code{double} directive
3828 @cindex floating point numbers (double)
3829 @code{.double} expects zero or more flonums, separated by commas. It
3830 assembles floating point numbers.
3832 The exact kind of floating point numbers emitted depends on how
3833 @code{@value{AS}} is configured. @xref{Machine Dependencies}.
3837 On the @value{TARGET} family @samp{.double} emits 64-bit floating-point numbers
3838 in @sc{ieee} format.
3843 @section @code{.eject}
3845 @cindex @code{eject} directive
3846 @cindex new page, in listings
3847 @cindex page, in listings
3848 @cindex listing control: new page
3849 Force a page break at this point, when generating assembly listings.
3852 @section @code{.else}
3854 @cindex @code{else} directive
3855 @code{.else} is part of the @code{@value{AS}} support for conditional
3856 assembly; @pxref{If,,@code{.if}}. It marks the beginning of a section
3857 of code to be assembled if the condition for the preceding @code{.if}
3861 @section @code{.elseif}
3863 @cindex @code{elseif} directive
3864 @code{.elseif} is part of the @code{@value{AS}} support for conditional
3865 assembly; @pxref{If,,@code{.if}}. It is shorthand for beginning a new
3866 @code{.if} block that would otherwise fill the entire @code{.else} section.
3869 @section @code{.end}
3871 @cindex @code{end} directive
3872 @code{.end} marks the end of the assembly file. @code{@value{AS}} does not
3873 process anything in the file past the @code{.end} directive.
3877 @section @code{.endef}
3879 @cindex @code{endef} directive
3880 This directive flags the end of a symbol definition begun with
3884 @samp{.endef} is only meaningful when generating COFF format output; if
3885 @code{@value{AS}} is configured to generate @code{b.out}, it accepts this
3886 directive but ignores it.
3891 @section @code{.endfunc}
3892 @cindex @code{endfunc} directive
3893 @code{.endfunc} marks the end of a function specified with @code{.func}.
3896 @section @code{.endif}
3898 @cindex @code{endif} directive
3899 @code{.endif} is part of the @code{@value{AS}} support for conditional assembly;
3900 it marks the end of a block of code that is only assembled
3901 conditionally. @xref{If,,@code{.if}}.
3904 @section @code{.equ @var{symbol}, @var{expression}}
3906 @cindex @code{equ} directive
3907 @cindex assigning values to symbols
3908 @cindex symbols, assigning values to
3909 This directive sets the value of @var{symbol} to @var{expression}.
3910 It is synonymous with @samp{.set}; @pxref{Set,,@code{.set}}.
3913 The syntax for @code{equ} on the HPPA is
3914 @samp{@var{symbol} .equ @var{expression}}.
3918 @section @code{.equiv @var{symbol}, @var{expression}}
3919 @cindex @code{equiv} directive
3920 The @code{.equiv} directive is like @code{.equ} and @code{.set}, except that
3921 the assembler will signal an error if @var{symbol} is already defined.
3923 Except for the contents of the error message, this is roughly equivalent to
3932 @section @code{.err}
3933 @cindex @code{err} directive
3934 If @code{@value{AS}} assembles a @code{.err} directive, it will print an error
3935 message and, unless the @code{-Z} option was used, it will not generate an
3936 object file. This can be used to signal error an conditionally compiled code.
3939 @section @code{.exitm}
3940 Exit early from the current macro definition. @xref{Macro}.
3943 @section @code{.extern}
3945 @cindex @code{extern} directive
3946 @code{.extern} is accepted in the source program---for compatibility
3947 with other assemblers---but it is ignored. @code{@value{AS}} treats
3948 all undefined symbols as external.
3951 @section @code{.fail @var{expression}}
3953 @cindex @code{fail} directive
3954 Generates an error or a warning. If the value of the @var{expression} is 500
3955 or more, @code{@value{AS}} will print a warning message. If the value is less
3956 than 500, @code{@value{AS}} will print an error message. The message will
3957 include the value of @var{expression}. This can occasionally be useful inside
3958 complex nested macros or conditional assembly.
3960 @ifclear no-file-dir
3962 @section @code{.file @var{string}}
3964 @cindex @code{file} directive
3965 @cindex logical file name
3966 @cindex file name, logical
3967 @code{.file} tells @code{@value{AS}} that we are about to start a new logical
3968 file. @var{string} is the new file name. In general, the filename is
3969 recognized whether or not it is surrounded by quotes @samp{"}; but if you wish
3970 to specify an empty file name, you must give the quotes--@code{""}. This
3971 statement may go away in future: it is only recognized to be compatible with
3972 old @code{@value{AS}} programs.
3974 In some configurations of @code{@value{AS}}, @code{.file} has already been
3975 removed to avoid conflicts with other assemblers. @xref{Machine Dependencies}.
3980 @section @code{.fill @var{repeat} , @var{size} , @var{value}}
3982 @cindex @code{fill} directive
3983 @cindex writing patterns in memory
3984 @cindex patterns, writing in memory
3985 @var{repeat}, @var{size} and @var{value} are absolute expressions.
3986 This emits @var{repeat} copies of @var{size} bytes. @var{Repeat}
3987 may be zero or more. @var{Size} may be zero or more, but if it is
3988 more than 8, then it is deemed to have the value 8, compatible with
3989 other people's assemblers. The contents of each @var{repeat} bytes
3990 is taken from an 8-byte number. The highest order 4 bytes are
3991 zero. The lowest order 4 bytes are @var{value} rendered in the
3992 byte-order of an integer on the computer @code{@value{AS}} is assembling for.
3993 Each @var{size} bytes in a repetition is taken from the lowest order
3994 @var{size} bytes of this number. Again, this bizarre behavior is
3995 compatible with other people's assemblers.
3997 @var{size} and @var{value} are optional.
3998 If the second comma and @var{value} are absent, @var{value} is
3999 assumed zero. If the first comma and following tokens are absent,
4000 @var{size} is assumed to be 1.
4003 @section @code{.float @var{flonums}}
4005 @cindex floating point numbers (single)
4006 @cindex @code{float} directive
4007 This directive assembles zero or more flonums, separated by commas. It
4008 has the same effect as @code{.single}.
4010 The exact kind of floating point numbers emitted depends on how
4011 @code{@value{AS}} is configured.
4012 @xref{Machine Dependencies}.
4016 On the @value{TARGET} family, @code{.float} emits 32-bit floating point numbers
4017 in @sc{ieee} format.
4022 @section @code{.func @var{name}[,@var{label}]}
4023 @cindex @code{func} directive
4024 @code{.func} emits debugging information to denote function @var{name}, and
4025 is ignored unless the file is assembled with debugging enabled.
4026 Only @samp{--gstabs} is currently supported.
4027 @var{label} is the entry point of the function and if omitted @var{name}
4028 prepended with the @samp{leading char} is used.
4029 @samp{leading char} is usually @code{_} or nothing, depending on the target.
4030 All functions are currently defined to have @code{void} return type.
4031 The function must be terminated with @code{.endfunc}.
4034 @section @code{.global @var{symbol}}, @code{.globl @var{symbol}}
4036 @cindex @code{global} directive
4037 @cindex symbol, making visible to linker
4038 @code{.global} makes the symbol visible to @code{@value{LD}}. If you define
4039 @var{symbol} in your partial program, its value is made available to
4040 other partial programs that are linked with it. Otherwise,
4041 @var{symbol} takes its attributes from a symbol of the same name
4042 from another file linked into the same program.
4044 Both spellings (@samp{.globl} and @samp{.global}) are accepted, for
4045 compatibility with other assemblers.
4048 On the HPPA, @code{.global} is not always enough to make it accessible to other
4049 partial programs. You may need the HPPA-only @code{.EXPORT} directive as well.
4050 @xref{HPPA Directives,, HPPA Assembler Directives}.
4055 @section @code{.hidden @var{names}}
4057 @cindex @code{.hidden} directive
4059 This one of the ELF visibility directives. The other two are
4060 @code{.internal} (@pxref{Internal,,@code{.internal}}) and
4061 @code{.protected} (@pxref{Protected,,@code{.protected}}).
4063 This directive overrides the named symbols default visibility (which is set by
4064 their binding: local, global or weak). The directive sets the visibility to
4065 @code{hidden} which means that the symbols are not visible to other components.
4066 Such symbols are always considered to be @code{protected} as well.
4070 @section @code{.hword @var{expressions}}
4072 @cindex @code{hword} directive
4073 @cindex integers, 16-bit
4074 @cindex numbers, 16-bit
4075 @cindex sixteen bit integers
4076 This expects zero or more @var{expressions}, and emits
4077 a 16 bit number for each.
4080 This directive is a synonym for @samp{.short}; depending on the target
4081 architecture, it may also be a synonym for @samp{.word}.
4085 This directive is a synonym for @samp{.short}.
4088 This directive is a synonym for both @samp{.short} and @samp{.word}.
4093 @section @code{.ident}
4095 @cindex @code{ident} directive
4096 This directive is used by some assemblers to place tags in object files.
4097 @code{@value{AS}} simply accepts the directive for source-file
4098 compatibility with such assemblers, but does not actually emit anything
4102 @section @code{.if @var{absolute expression}}
4104 @cindex conditional assembly
4105 @cindex @code{if} directive
4106 @code{.if} marks the beginning of a section of code which is only
4107 considered part of the source program being assembled if the argument
4108 (which must be an @var{absolute expression}) is non-zero. The end of
4109 the conditional section of code must be marked by @code{.endif}
4110 (@pxref{Endif,,@code{.endif}}); optionally, you may include code for the
4111 alternative condition, flagged by @code{.else} (@pxref{Else,,@code{.else}}).
4112 If you have several conditions to check, @code{.elseif} may be used to avoid
4113 nesting blocks if/else within each subsequent @code{.else} block.
4115 The following variants of @code{.if} are also supported:
4117 @cindex @code{ifdef} directive
4118 @item .ifdef @var{symbol}
4119 Assembles the following section of code if the specified @var{symbol}
4122 @cindex @code{ifc} directive
4123 @item .ifc @var{string1},@var{string2}
4124 Assembles the following section of code if the two strings are the same. The
4125 strings may be optionally quoted with single quotes. If they are not quoted,
4126 the first string stops at the first comma, and the second string stops at the
4127 end of the line. Strings which contain whitespace should be quoted. The
4128 string comparison is case sensitive.
4130 @cindex @code{ifeq} directive
4131 @item .ifeq @var{absolute expression}
4132 Assembles the following section of code if the argument is zero.
4134 @cindex @code{ifeqs} directive
4135 @item .ifeqs @var{string1},@var{string2}
4136 Another form of @code{.ifc}. The strings must be quoted using double quotes.
4138 @cindex @code{ifge} directive
4139 @item .ifge @var{absolute expression}
4140 Assembles the following section of code if the argument is greater than or
4143 @cindex @code{ifgt} directive
4144 @item .ifgt @var{absolute expression}
4145 Assembles the following section of code if the argument is greater than zero.
4147 @cindex @code{ifle} directive
4148 @item .ifle @var{absolute expression}
4149 Assembles the following section of code if the argument is less than or equal
4152 @cindex @code{iflt} directive
4153 @item .iflt @var{absolute expression}
4154 Assembles the following section of code if the argument is less than zero.
4156 @cindex @code{ifnc} directive
4157 @item .ifnc @var{string1},@var{string2}.
4158 Like @code{.ifc}, but the sense of the test is reversed: this assembles the
4159 following section of code if the two strings are not the same.
4161 @cindex @code{ifndef} directive
4162 @cindex @code{ifnotdef} directive
4163 @item .ifndef @var{symbol}
4164 @itemx .ifnotdef @var{symbol}
4165 Assembles the following section of code if the specified @var{symbol}
4166 has not been defined. Both spelling variants are equivalent.
4168 @cindex @code{ifne} directive
4169 @item .ifne @var{absolute expression}
4170 Assembles the following section of code if the argument is not equal to zero
4171 (in other words, this is equivalent to @code{.if}).
4173 @cindex @code{ifnes} directive
4174 @item .ifnes @var{string1},@var{string2}
4175 Like @code{.ifeqs}, but the sense of the test is reversed: this assembles the
4176 following section of code if the two strings are not the same.
4180 @section @code{.incbin "@var{file}"[,@var{skip}[,@var{count}]]}
4182 @cindex @code{incbin} directive
4183 @cindex binary files, including
4184 The @code{incbin} directive includes @var{file} verbatim at the current
4185 location. You can control the search paths used with the @samp{-I} command-line
4186 option (@pxref{Invoking,,Command-Line Options}). Quotation marks are required
4189 The @var{skip} argument skips a number of bytes from the start of the
4190 @var{file}. The @var{count} argument indicates the maximum number of bytes to
4191 read. Note that the data is not aligned in any way, so it is the user's
4192 responsibility to make sure that proper alignment is provided both before and
4193 after the @code{incbin} directive.
4196 @section @code{.include "@var{file}"}
4198 @cindex @code{include} directive
4199 @cindex supporting files, including
4200 @cindex files, including
4201 This directive provides a way to include supporting files at specified
4202 points in your source program. The code from @var{file} is assembled as
4203 if it followed the point of the @code{.include}; when the end of the
4204 included file is reached, assembly of the original file continues. You
4205 can control the search paths used with the @samp{-I} command-line option
4206 (@pxref{Invoking,,Command-Line Options}). Quotation marks are required
4210 @section @code{.int @var{expressions}}
4212 @cindex @code{int} directive
4213 @cindex integers, 32-bit
4214 Expect zero or more @var{expressions}, of any section, separated by commas.
4215 For each expression, emit a number that, at run time, is the value of that
4216 expression. The byte order and bit size of the number depends on what kind
4217 of target the assembly is for.
4221 On the H8/500 and most forms of the H8/300, @code{.int} emits 16-bit
4222 integers. On the H8/300H and the Hitachi SH, however, @code{.int} emits
4229 @section @code{.internal @var{names}}
4231 @cindex @code{.internal} directive
4233 This one of the ELF visibility directives. The other two are
4234 @code{.hidden} (@pxref{Hidden,,@code{.hidden}}) and
4235 @code{.protected} (@pxref{Protected,,@code{.protected}}).
4237 This directive overrides the named symbols default visibility (which is set by
4238 their binding: local, global or weak). The directive sets the visibility to
4239 @code{internal} which means that the symbols are considered to be @code{hidden}
4240 (ie not visible to other components), and that some extra, processor specific
4241 processing must also be performed upon the symbols as well.
4245 @section @code{.irp @var{symbol},@var{values}}@dots{}
4247 @cindex @code{irp} directive
4248 Evaluate a sequence of statements assigning different values to @var{symbol}.
4249 The sequence of statements starts at the @code{.irp} directive, and is
4250 terminated by an @code{.endr} directive. For each @var{value}, @var{symbol} is
4251 set to @var{value}, and the sequence of statements is assembled. If no
4252 @var{value} is listed, the sequence of statements is assembled once, with
4253 @var{symbol} set to the null string. To refer to @var{symbol} within the
4254 sequence of statements, use @var{\symbol}.
4256 For example, assembling
4264 is equivalent to assembling
4273 @section @code{.irpc @var{symbol},@var{values}}@dots{}
4275 @cindex @code{irpc} directive
4276 Evaluate a sequence of statements assigning different values to @var{symbol}.
4277 The sequence of statements starts at the @code{.irpc} directive, and is
4278 terminated by an @code{.endr} directive. For each character in @var{value},
4279 @var{symbol} is set to the character, and the sequence of statements is
4280 assembled. If no @var{value} is listed, the sequence of statements is
4281 assembled once, with @var{symbol} set to the null string. To refer to
4282 @var{symbol} within the sequence of statements, use @var{\symbol}.
4284 For example, assembling
4292 is equivalent to assembling
4301 @section @code{.lcomm @var{symbol} , @var{length}}
4303 @cindex @code{lcomm} directive
4304 @cindex local common symbols
4305 @cindex symbols, local common
4306 Reserve @var{length} (an absolute expression) bytes for a local common
4307 denoted by @var{symbol}. The section and value of @var{symbol} are
4308 those of the new local common. The addresses are allocated in the bss
4309 section, so that at run-time the bytes start off zeroed. @var{Symbol}
4310 is not declared global (@pxref{Global,,@code{.global}}), so is normally
4311 not visible to @code{@value{LD}}.
4314 Some targets permit a third argument to be used with @code{.lcomm}. This
4315 argument specifies the desired alignment of the symbol in the bss section.
4319 The syntax for @code{.lcomm} differs slightly on the HPPA. The syntax is
4320 @samp{@var{symbol} .lcomm, @var{length}}; @var{symbol} is optional.
4324 @section @code{.lflags}
4326 @cindex @code{lflags} directive (ignored)
4327 @code{@value{AS}} accepts this directive, for compatibility with other
4328 assemblers, but ignores it.
4330 @ifclear no-line-dir
4332 @section @code{.line @var{line-number}}
4334 @cindex @code{line} directive
4338 @section @code{.ln @var{line-number}}
4340 @cindex @code{ln} directive
4342 @cindex logical line number
4344 Change the logical line number. @var{line-number} must be an absolute
4345 expression. The next line has that logical line number. Therefore any other
4346 statements on the current line (after a statement separator character) are
4347 reported as on logical line number @var{line-number} @minus{} 1. One day
4348 @code{@value{AS}} will no longer support this directive: it is recognized only
4349 for compatibility with existing assembler programs.
4353 @emph{Warning:} In the AMD29K configuration of @value{AS}, this command is
4354 not available; use the synonym @code{.ln} in that context.
4359 @ifclear no-line-dir
4360 Even though this is a directive associated with the @code{a.out} or
4361 @code{b.out} object-code formats, @code{@value{AS}} still recognizes it
4362 when producing COFF output, and treats @samp{.line} as though it
4363 were the COFF @samp{.ln} @emph{if} it is found outside a
4364 @code{.def}/@code{.endef} pair.
4366 Inside a @code{.def}, @samp{.line} is, instead, one of the directives
4367 used by compilers to generate auxiliary symbol information for
4372 @section @code{.linkonce [@var{type}]}
4374 @cindex @code{linkonce} directive
4375 @cindex common sections
4376 Mark the current section so that the linker only includes a single copy of it.
4377 This may be used to include the same section in several different object files,
4378 but ensure that the linker will only include it once in the final output file.
4379 The @code{.linkonce} pseudo-op must be used for each instance of the section.
4380 Duplicate sections are detected based on the section name, so it should be
4383 This directive is only supported by a few object file formats; as of this
4384 writing, the only object file format which supports it is the Portable
4385 Executable format used on Windows NT.
4387 The @var{type} argument is optional. If specified, it must be one of the
4388 following strings. For example:
4392 Not all types may be supported on all object file formats.
4396 Silently discard duplicate sections. This is the default.
4399 Warn if there are duplicate sections, but still keep only one copy.
4402 Warn if any of the duplicates have different sizes.
4405 Warn if any of the duplicates do not have exactly the same contents.
4409 @section @code{.ln @var{line-number}}
4411 @cindex @code{ln} directive
4412 @ifclear no-line-dir
4413 @samp{.ln} is a synonym for @samp{.line}.
4416 Tell @code{@value{AS}} to change the logical line number. @var{line-number}
4417 must be an absolute expression. The next line has that logical
4418 line number, so any other statements on the current line (after a
4419 statement separator character @code{;}) are reported as on logical
4420 line number @var{line-number} @minus{} 1.
4423 This directive is accepted, but ignored, when @code{@value{AS}} is
4424 configured for @code{b.out}; its effect is only associated with COFF
4430 @section @code{.mri @var{val}}
4432 @cindex @code{mri} directive
4433 @cindex MRI mode, temporarily
4434 If @var{val} is non-zero, this tells @code{@value{AS}} to enter MRI mode. If
4435 @var{val} is zero, this tells @code{@value{AS}} to exit MRI mode. This change
4436 affects code assembled until the next @code{.mri} directive, or until the end
4437 of the file. @xref{M, MRI mode, MRI mode}.
4440 @section @code{.list}
4442 @cindex @code{list} directive
4443 @cindex listing control, turning on
4444 Control (in conjunction with the @code{.nolist} directive) whether or
4445 not assembly listings are generated. These two directives maintain an
4446 internal counter (which is zero initially). @code{.list} increments the
4447 counter, and @code{.nolist} decrements it. Assembly listings are
4448 generated whenever the counter is greater than zero.
4450 By default, listings are disabled. When you enable them (with the
4451 @samp{-a} command line option; @pxref{Invoking,,Command-Line Options}),
4452 the initial value of the listing counter is one.
4455 @section @code{.long @var{expressions}}
4457 @cindex @code{long} directive
4458 @code{.long} is the same as @samp{.int}, @pxref{Int,,@code{.int}}.
4461 @c no one seems to know what this is for or whether this description is
4462 @c what it really ought to do
4464 @section @code{.lsym @var{symbol}, @var{expression}}
4466 @cindex @code{lsym} directive
4467 @cindex symbol, not referenced in assembly
4468 @code{.lsym} creates a new symbol named @var{symbol}, but does not put it in
4469 the hash table, ensuring it cannot be referenced by name during the
4470 rest of the assembly. This sets the attributes of the symbol to be
4471 the same as the expression value:
4473 @var{other} = @var{descriptor} = 0
4474 @var{type} = @r{(section of @var{expression})}
4475 @var{value} = @var{expression}
4478 The new symbol is not flagged as external.
4482 @section @code{.macro}
4485 The commands @code{.macro} and @code{.endm} allow you to define macros that
4486 generate assembly output. For example, this definition specifies a macro
4487 @code{sum} that puts a sequence of numbers into memory:
4490 .macro sum from=0, to=5
4499 With that definition, @samp{SUM 0,5} is equivalent to this assembly input:
4511 @item .macro @var{macname}
4512 @itemx .macro @var{macname} @var{macargs} @dots{}
4513 @cindex @code{macro} directive
4514 Begin the definition of a macro called @var{macname}. If your macro
4515 definition requires arguments, specify their names after the macro name,
4516 separated by commas or spaces. You can supply a default value for any
4517 macro argument by following the name with @samp{=@var{deflt}}. For
4518 example, these are all valid @code{.macro} statements:
4522 Begin the definition of a macro called @code{comm}, which takes no
4525 @item .macro plus1 p, p1
4526 @itemx .macro plus1 p p1
4527 Either statement begins the definition of a macro called @code{plus1},
4528 which takes two arguments; within the macro definition, write
4529 @samp{\p} or @samp{\p1} to evaluate the arguments.
4531 @item .macro reserve_str p1=0 p2
4532 Begin the definition of a macro called @code{reserve_str}, with two
4533 arguments. The first argument has a default value, but not the second.
4534 After the definition is complete, you can call the macro either as
4535 @samp{reserve_str @var{a},@var{b}} (with @samp{\p1} evaluating to
4536 @var{a} and @samp{\p2} evaluating to @var{b}), or as @samp{reserve_str
4537 ,@var{b}} (with @samp{\p1} evaluating as the default, in this case
4538 @samp{0}, and @samp{\p2} evaluating to @var{b}).
4541 When you call a macro, you can specify the argument values either by
4542 position, or by keyword. For example, @samp{sum 9,17} is equivalent to
4543 @samp{sum to=17, from=9}.
4546 @cindex @code{endm} directive
4547 Mark the end of a macro definition.
4550 @cindex @code{exitm} directive
4551 Exit early from the current macro definition.
4553 @cindex number of macros executed
4554 @cindex macros, count executed
4556 @code{@value{AS}} maintains a counter of how many macros it has
4557 executed in this pseudo-variable; you can copy that number to your
4558 output with @samp{\@@}, but @emph{only within a macro definition}.
4561 @item LOCAL @var{name} [ , @dots{} ]
4562 @emph{Warning: @code{LOCAL} is only available if you select ``alternate
4563 macro syntax'' with @samp{-a} or @samp{--alternate}.} @xref{Alternate,,
4564 Alternate macro syntax}.
4566 Generate a string replacement for each of the @var{name} arguments, and
4567 replace any instances of @var{name} in each macro expansion. The
4568 replacement string is unique in the assembly, and different for each
4569 separate macro expansion. @code{LOCAL} allows you to write macros that
4570 define symbols, without fear of conflict between separate macro expansions.
4575 @section @code{.nolist}
4577 @cindex @code{nolist} directive
4578 @cindex listing control, turning off
4579 Control (in conjunction with the @code{.list} directive) whether or
4580 not assembly listings are generated. These two directives maintain an
4581 internal counter (which is zero initially). @code{.list} increments the
4582 counter, and @code{.nolist} decrements it. Assembly listings are
4583 generated whenever the counter is greater than zero.
4586 @section @code{.octa @var{bignums}}
4588 @c FIXME: double size emitted for "octa" on i960, others? Or warn?
4589 @cindex @code{octa} directive
4590 @cindex integer, 16-byte
4591 @cindex sixteen byte integer
4592 This directive expects zero or more bignums, separated by commas. For each
4593 bignum, it emits a 16-byte integer.
4595 The term ``octa'' comes from contexts in which a ``word'' is two bytes;
4596 hence @emph{octa}-word for 16 bytes.
4599 @section @code{.org @var{new-lc} , @var{fill}}
4601 @cindex @code{org} directive
4602 @cindex location counter, advancing
4603 @cindex advancing location counter
4604 @cindex current address, advancing
4605 Advance the location counter of the current section to
4606 @var{new-lc}. @var{new-lc} is either an absolute expression or an
4607 expression with the same section as the current subsection. That is,
4608 you can't use @code{.org} to cross sections: if @var{new-lc} has the
4609 wrong section, the @code{.org} directive is ignored. To be compatible
4610 with former assemblers, if the section of @var{new-lc} is absolute,
4611 @code{@value{AS}} issues a warning, then pretends the section of @var{new-lc}
4612 is the same as the current subsection.
4614 @code{.org} may only increase the location counter, or leave it
4615 unchanged; you cannot use @code{.org} to move the location counter
4618 @c double negative used below "not undefined" because this is a specific
4619 @c reference to "undefined" (as SEG_UNKNOWN is called in this manual)
4620 @c section. doc@cygnus.com 18feb91
4621 Because @code{@value{AS}} tries to assemble programs in one pass, @var{new-lc}
4622 may not be undefined. If you really detest this restriction we eagerly await
4623 a chance to share your improved assembler.
4625 Beware that the origin is relative to the start of the section, not
4626 to the start of the subsection. This is compatible with other
4627 people's assemblers.
4629 When the location counter (of the current subsection) is advanced, the
4630 intervening bytes are filled with @var{fill} which should be an
4631 absolute expression. If the comma and @var{fill} are omitted,
4632 @var{fill} defaults to zero.
4635 @section @code{.p2align[wl] @var{abs-expr}, @var{abs-expr}, @var{abs-expr}}
4637 @cindex padding the location counter given a power of two
4638 @cindex @code{p2align} directive
4639 Pad the location counter (in the current subsection) to a particular
4640 storage boundary. The first expression (which must be absolute) is the
4641 number of low-order zero bits the location counter must have after
4642 advancement. For example @samp{.p2align 3} advances the location
4643 counter until it a multiple of 8. If the location counter is already a
4644 multiple of 8, no change is needed.
4646 The second expression (also absolute) gives the fill value to be stored in the
4647 padding bytes. It (and the comma) may be omitted. If it is omitted, the
4648 padding bytes are normally zero. However, on some systems, if the section is
4649 marked as containing code and the fill value is omitted, the space is filled
4650 with no-op instructions.
4652 The third expression is also absolute, and is also optional. If it is present,
4653 it is the maximum number of bytes that should be skipped by this alignment
4654 directive. If doing the alignment would require skipping more bytes than the
4655 specified maximum, then the alignment is not done at all. You can omit the
4656 fill value (the second argument) entirely by simply using two commas after the
4657 required alignment; this can be useful if you want the alignment to be filled
4658 with no-op instructions when appropriate.
4660 @cindex @code{p2alignw} directive
4661 @cindex @code{p2alignl} directive
4662 The @code{.p2alignw} and @code{.p2alignl} directives are variants of the
4663 @code{.p2align} directive. The @code{.p2alignw} directive treats the fill
4664 pattern as a two byte word value. The @code{.p2alignl} directives treats the
4665 fill pattern as a four byte longword value. For example, @code{.p2alignw
4666 2,0x368d} will align to a multiple of 4. If it skips two bytes, they will be
4667 filled in with the value 0x368d (the exact placement of the bytes depends upon
4668 the endianness of the processor). If it skips 1 or 3 bytes, the fill value is
4673 @section @code{.previous}
4675 @cindex @code{.previous} directive
4676 @cindex Section Stack
4677 This is one of the ELF section stack manipulation directives. The others are
4678 @code{.section} (@pxref{Section}), @code{.subsection} (@pxref{SubSection}),
4679 @code{.pushsection} (@pxref{PushSection}), and @code{.popsection}
4680 (@pxref{PopSection}).
4682 This directive swaps the current section (and subsection) with most recently
4683 referenced section (and subsection) prior to this one. Multiple
4684 @code{.previous} directives in a row will flip between two sections (and their
4687 In terms of the section stack, this directive swaps the current section with
4688 the top section on the section stack.
4693 @section @code{.popsection}
4695 @cindex @code{.popsection} directive
4696 @cindex Section Stack
4697 This is one of the ELF section stack manipulation directives. The others are
4698 @code{.section} (@pxref{Section}), @code{.subsection} (@pxref{SubSection}),
4699 @code{.pushsection} (@pxref{PushSection}), and @code{.previous}
4702 This directive replaces the current section (and subsection) with the top
4703 section (and subsection) on the section stack. This section is popped off the
4708 @section @code{.print @var{string}}
4710 @cindex @code{print} directive
4711 @code{@value{AS}} will print @var{string} on the standard output during
4712 assembly. You must put @var{string} in double quotes.
4716 @section @code{.protected @var{names}}
4718 @cindex @code{.protected} directive
4720 This one of the ELF visibility directives. The other two are
4721 @code{.hidden} (@pxref{Hidden}) and @code{.internal} (@pxref{Internal}).
4723 This directive overrides the named symbols default visibility (which is set by
4724 their binding: local, global or weak). The directive sets the visibility to
4725 @code{protected} which means that any references to the symbols from within the
4726 components that defines them must be resolved to the definition in that
4727 component, even if a definition in another component would normally preempt
4732 @section @code{.psize @var{lines} , @var{columns}}
4734 @cindex @code{psize} directive
4735 @cindex listing control: paper size
4736 @cindex paper size, for listings
4737 Use this directive to declare the number of lines---and, optionally, the
4738 number of columns---to use for each page, when generating listings.
4740 If you do not use @code{.psize}, listings use a default line-count
4741 of 60. You may omit the comma and @var{columns} specification; the
4742 default width is 200 columns.
4744 @code{@value{AS}} generates formfeeds whenever the specified number of
4745 lines is exceeded (or whenever you explicitly request one, using
4748 If you specify @var{lines} as @code{0}, no formfeeds are generated save
4749 those explicitly specified with @code{.eject}.
4752 @section @code{.purgem @var{name}}
4754 @cindex @code{purgem} directive
4755 Undefine the macro @var{name}, so that later uses of the string will not be
4756 expanded. @xref{Macro}.
4760 @section @code{.pushsection @var{name} , @var{subsection}}
4762 @cindex @code{.pushsection} directive
4763 @cindex Section Stack
4764 This is one of the ELF section stack manipulation directives. The others are
4765 @code{.section} (@pxref{Section}), @code{.subsection} (@pxref{SubSection}),
4766 @code{.popsection} (@pxref{PopSection}), and @code{.previous}
4769 This directive is a synonym for @code{.section}. It pushes the current section
4770 (and subsection) onto the top of the section stack, and then replaces the
4771 current section and subsection with @code{name} and @code{subsection}.
4775 @section @code{.quad @var{bignums}}
4777 @cindex @code{quad} directive
4778 @code{.quad} expects zero or more bignums, separated by commas. For
4779 each bignum, it emits
4781 an 8-byte integer. If the bignum won't fit in 8 bytes, it prints a
4782 warning message; and just takes the lowest order 8 bytes of the bignum.
4783 @cindex eight-byte integer
4784 @cindex integer, 8-byte
4786 The term ``quad'' comes from contexts in which a ``word'' is two bytes;
4787 hence @emph{quad}-word for 8 bytes.
4790 a 16-byte integer. If the bignum won't fit in 16 bytes, it prints a
4791 warning message; and just takes the lowest order 16 bytes of the bignum.
4792 @cindex sixteen-byte integer
4793 @cindex integer, 16-byte
4797 @section @code{.rept @var{count}}
4799 @cindex @code{rept} directive
4800 Repeat the sequence of lines between the @code{.rept} directive and the next
4801 @code{.endr} directive @var{count} times.
4803 For example, assembling
4811 is equivalent to assembling
4820 @section @code{.sbttl "@var{subheading}"}
4822 @cindex @code{sbttl} directive
4823 @cindex subtitles for listings
4824 @cindex listing control: subtitle
4825 Use @var{subheading} as the title (third line, immediately after the
4826 title line) when generating assembly listings.
4828 This directive affects subsequent pages, as well as the current page if
4829 it appears within ten lines of the top of a page.
4833 @section @code{.scl @var{class}}
4835 @cindex @code{scl} directive
4836 @cindex symbol storage class (COFF)
4837 @cindex COFF symbol storage class
4838 Set the storage-class value for a symbol. This directive may only be
4839 used inside a @code{.def}/@code{.endef} pair. Storage class may flag
4840 whether a symbol is static or external, or it may record further
4841 symbolic debugging information.
4844 The @samp{.scl} directive is primarily associated with COFF output; when
4845 configured to generate @code{b.out} output format, @code{@value{AS}}
4846 accepts this directive but ignores it.
4851 @section @code{.section @var{name}} (COFF version)
4853 @cindex @code{section} directive
4854 @cindex named section
4855 Use the @code{.section} directive to assemble the following code into a section
4858 This directive is only supported for targets that actually support arbitrarily
4859 named sections; on @code{a.out} targets, for example, it is not accepted, even
4860 with a standard @code{a.out} section name.
4862 For COFF targets, the @code{.section} directive is used in one of the following
4866 .section @var{name}[, "@var{flags}"]
4867 .section @var{name}[, @var{subsegment}]
4870 If the optional argument is quoted, it is taken as flags to use for the
4871 section. Each flag is a single character. The following flags are recognized:
4874 bss section (uninitialized data)
4876 section is not loaded
4886 shared section (meaningful for PE targets)
4889 If no flags are specified, the default flags depend upon the section name. If
4890 the section name is not recognized, the default will be for the section to be
4891 loaded and writable. Note the @code{n} and @code{w} flags remove attributes
4892 from the section, rather than adding them, so if they are used on their own it
4893 will be as if no flags had been specified at all.
4895 If the optional argument to the @code{.section} directive is not quoted, it is
4896 taken as a subsegment number (@pxref{Sub-Sections}).
4899 @section @code{.section @var{name}} (ELF version)
4901 @cindex @code{section} directive
4902 @cindex named section
4904 @cindex Section Stack
4905 This is one of the ELF section stack manipulation directives. The others are
4906 @code{.subsection} (@pxref{SubSection}), @code{.pushsection}
4907 (@pxref{PushSection}), @code{.popsection} (@pxref{PopSection}), and
4908 @code{.previous} (@pxref{Previous}).
4911 For ELF targets, the @code{.section} directive is used like this:
4914 .section @var{name} [, "@var{flags}"[, @@@var{type}[, @@@var{entsize}]]]
4917 The optional @var{flags} argument is a quoted string which may contain any
4918 combination of the following characters:
4921 section is allocatable
4925 section is executable
4927 section is mergeable
4929 section contains zero terminated strings
4932 The optional @var{type} argument may contain one of the following constants:
4935 section contains data
4937 section does not contain data (i.e., section only occupies space)
4940 If @var{flags} contains @code{M} flag, @var{type} argument must be specified
4941 as well as @var{entsize} argument. Sections with @code{M} flag but not
4942 @code{S} flag must contain fixed size constants, each @var{entsize} octets
4943 long. Sections with both @code{M} and @code{S} must contain zero terminated
4944 strings where each character is @var{entsize} bytes long. The linker may remove
4945 duplicates within sections with the same name, same entity size and same flags.
4947 If no flags are specified, the default flags depend upon the section name. If
4948 the section name is not recognized, the default will be for the section to have
4949 none of the above flags: it will not be allocated in memory, nor writable, nor
4950 executable. The section will contain data.
4952 For ELF targets, the assembler supports another type of @code{.section}
4953 directive for compatibility with the Solaris assembler:
4956 .section "@var{name}"[, @var{flags}...]
4959 Note that the section name is quoted. There may be a sequence of comma
4963 section is allocatable
4967 section is executable
4970 This directive replaces the current section and subsection. The replaced
4971 section and subsection are pushed onto the section stack. See the contents of
4972 the gas testsuite directory @code{gas/testsuite/gas/elf} for some examples of
4973 how this directive and the other section stack directives work.
4976 @section @code{.set @var{symbol}, @var{expression}}
4978 @cindex @code{set} directive
4979 @cindex symbol value, setting
4980 Set the value of @var{symbol} to @var{expression}. This
4981 changes @var{symbol}'s value and type to conform to
4982 @var{expression}. If @var{symbol} was flagged as external, it remains
4983 flagged (@pxref{Symbol Attributes}).
4985 You may @code{.set} a symbol many times in the same assembly.
4987 If you @code{.set} a global symbol, the value stored in the object
4988 file is the last value stored into it.
4991 The syntax for @code{set} on the HPPA is
4992 @samp{@var{symbol} .set @var{expression}}.
4996 @section @code{.short @var{expressions}}
4998 @cindex @code{short} directive
5000 @code{.short} is normally the same as @samp{.word}.
5001 @xref{Word,,@code{.word}}.
5003 In some configurations, however, @code{.short} and @code{.word} generate
5004 numbers of different lengths; @pxref{Machine Dependencies}.
5008 @code{.short} is the same as @samp{.word}. @xref{Word,,@code{.word}}.
5011 This expects zero or more @var{expressions}, and emits
5012 a 16 bit number for each.
5017 @section @code{.single @var{flonums}}
5019 @cindex @code{single} directive
5020 @cindex floating point numbers (single)
5021 This directive assembles zero or more flonums, separated by commas. It
5022 has the same effect as @code{.float}.
5024 The exact kind of floating point numbers emitted depends on how
5025 @code{@value{AS}} is configured. @xref{Machine Dependencies}.
5029 On the @value{TARGET} family, @code{.single} emits 32-bit floating point
5030 numbers in @sc{ieee} format.
5035 @section @code{.size} (COFF version)
5037 @cindex @code{size} directive
5038 This directive is generated by compilers to include auxiliary debugging
5039 information in the symbol table. It is only permitted inside
5040 @code{.def}/@code{.endef} pairs.
5043 @samp{.size} is only meaningful when generating COFF format output; when
5044 @code{@value{AS}} is generating @code{b.out}, it accepts this directive but
5048 @section @code{.size @var{name} , @var{expression}} (ELF version)
5049 @cindex @code{size} directive
5051 This directive is used to set the size associated with a symbol @var{name}.
5052 The size in bytes is computed from @var{expression} which can make use of label
5053 arithmetic. This directive is typically used to set the size of function
5057 @section @code{.sleb128 @var{expressions}}
5059 @cindex @code{sleb128} directive
5060 @var{sleb128} stands for ``signed little endian base 128.'' This is a
5061 compact, variable length representation of numbers used by the DWARF
5062 symbolic debugging format. @xref{Uleb128,@code{.uleb128}}.
5064 @ifclear no-space-dir
5066 @section @code{.skip @var{size} , @var{fill}}
5068 @cindex @code{skip} directive
5069 @cindex filling memory
5070 This directive emits @var{size} bytes, each of value @var{fill}. Both
5071 @var{size} and @var{fill} are absolute expressions. If the comma and
5072 @var{fill} are omitted, @var{fill} is assumed to be zero. This is the same as
5076 @section @code{.space @var{size} , @var{fill}}
5078 @cindex @code{space} directive
5079 @cindex filling memory
5080 This directive emits @var{size} bytes, each of value @var{fill}. Both
5081 @var{size} and @var{fill} are absolute expressions. If the comma
5082 and @var{fill} are omitted, @var{fill} is assumed to be zero. This is the same
5087 @emph{Warning:} @code{.space} has a completely different meaning for HPPA
5088 targets; use @code{.block} as a substitute. See @cite{HP9000 Series 800
5089 Assembly Language Reference Manual} (HP 92432-90001) for the meaning of the
5090 @code{.space} directive. @xref{HPPA Directives,,HPPA Assembler Directives},
5099 @section @code{.space}
5100 @cindex @code{space} directive
5102 On the AMD 29K, this directive is ignored; it is accepted for
5103 compatibility with other AMD 29K assemblers.
5106 @emph{Warning:} In most versions of the @sc{gnu} assembler, the directive
5107 @code{.space} has the effect of @code{.block} @xref{Machine Dependencies}.
5113 @section @code{.stabd, .stabn, .stabs}
5115 @cindex symbolic debuggers, information for
5116 @cindex @code{stab@var{x}} directives
5117 There are three directives that begin @samp{.stab}.
5118 All emit symbols (@pxref{Symbols}), for use by symbolic debuggers.
5119 The symbols are not entered in the @code{@value{AS}} hash table: they
5120 cannot be referenced elsewhere in the source file.
5121 Up to five fields are required:
5125 This is the symbol's name. It may contain any character except
5126 @samp{\000}, so is more general than ordinary symbol names. Some
5127 debuggers used to code arbitrarily complex structures into symbol names
5131 An absolute expression. The symbol's type is set to the low 8 bits of
5132 this expression. Any bit pattern is permitted, but @code{@value{LD}}
5133 and debuggers choke on silly bit patterns.
5136 An absolute expression. The symbol's ``other'' attribute is set to the
5137 low 8 bits of this expression.
5140 An absolute expression. The symbol's descriptor is set to the low 16
5141 bits of this expression.
5144 An absolute expression which becomes the symbol's value.
5147 If a warning is detected while reading a @code{.stabd}, @code{.stabn},
5148 or @code{.stabs} statement, the symbol has probably already been created;
5149 you get a half-formed symbol in your object file. This is
5150 compatible with earlier assemblers!
5153 @cindex @code{stabd} directive
5154 @item .stabd @var{type} , @var{other} , @var{desc}
5156 The ``name'' of the symbol generated is not even an empty string.
5157 It is a null pointer, for compatibility. Older assemblers used a
5158 null pointer so they didn't waste space in object files with empty
5161 The symbol's value is set to the location counter,
5162 relocatably. When your program is linked, the value of this symbol
5163 is the address of the location counter when the @code{.stabd} was
5166 @cindex @code{stabn} directive
5167 @item .stabn @var{type} , @var{other} , @var{desc} , @var{value}
5168 The name of the symbol is set to the empty string @code{""}.
5170 @cindex @code{stabs} directive
5171 @item .stabs @var{string} , @var{type} , @var{other} , @var{desc} , @var{value}
5172 All five fields are specified.
5178 @section @code{.string} "@var{str}"
5180 @cindex string, copying to object file
5181 @cindex @code{string} directive
5183 Copy the characters in @var{str} to the object file. You may specify more than
5184 one string to copy, separated by commas. Unless otherwise specified for a
5185 particular machine, the assembler marks the end of each string with a 0 byte.
5186 You can use any of the escape sequences described in @ref{Strings,,Strings}.
5189 @section @code{.struct @var{expression}}
5191 @cindex @code{struct} directive
5192 Switch to the absolute section, and set the section offset to @var{expression},
5193 which must be an absolute expression. You might use this as follows:
5202 This would define the symbol @code{field1} to have the value 0, the symbol
5203 @code{field2} to have the value 4, and the symbol @code{field3} to have the
5204 value 8. Assembly would be left in the absolute section, and you would need to
5205 use a @code{.section} directive of some sort to change to some other section
5206 before further assembly.
5210 @section @code{.subsection @var{name}}
5212 @cindex @code{.subsection} directive
5213 @cindex Section Stack
5214 This is one of the ELF section stack manipulation directives. The others are
5215 @code{.section} (@pxref{Section}), @code{.pushsection} (@pxref{PushSection}),
5216 @code{.popsection} (@pxref{PopSection}), and @code{.previous}
5219 This directive replaces the current subsection with @code{name}. The current
5220 section is not changed. The replaced subsection is put onto the section stack
5221 in place of the then current top of stack subsection.
5226 @section @code{.symver}
5227 @cindex @code{symver} directive
5228 @cindex symbol versioning
5229 @cindex versions of symbols
5230 Use the @code{.symver} directive to bind symbols to specific version nodes
5231 within a source file. This is only supported on ELF platforms, and is
5232 typically used when assembling files to be linked into a shared library.
5233 There are cases where it may make sense to use this in objects to be bound
5234 into an application itself so as to override a versioned symbol from a
5237 For ELF targets, the @code{.symver} directive can be used like this:
5239 .symver @var{name}, @var{name2@@nodename}
5241 If the symbol @var{name} is defined within the file
5242 being assembled, the @code{.symver} directive effectively creates a symbol
5243 alias with the name @var{name2@@nodename}, and in fact the main reason that we
5244 just don't try and create a regular alias is that the @var{@@} character isn't
5245 permitted in symbol names. The @var{name2} part of the name is the actual name
5246 of the symbol by which it will be externally referenced. The name @var{name}
5247 itself is merely a name of convenience that is used so that it is possible to
5248 have definitions for multiple versions of a function within a single source
5249 file, and so that the compiler can unambiguously know which version of a
5250 function is being mentioned. The @var{nodename} portion of the alias should be
5251 the name of a node specified in the version script supplied to the linker when
5252 building a shared library. If you are attempting to override a versioned
5253 symbol from a shared library, then @var{nodename} should correspond to the
5254 nodename of the symbol you are trying to override.
5256 If the symbol @var{name} is not defined within the file being assembled, all
5257 references to @var{name} will be changed to @var{name2@@nodename}. If no
5258 reference to @var{name} is made, @var{name2@@nodename} will be removed from the
5261 Another usage of the @code{.symver} directive is:
5263 .symver @var{name}, @var{name2@@@@nodename}
5265 In this case, the symbol @var{name} must exist and be defined within
5266 the file being assembled. It is similar to @var{name2@@nodename}. The
5267 difference is @var{name2@@@@nodename} will also be used to resolve
5268 references to @var{name2} by the linker.
5270 The third usage of the @code{.symver} directive is:
5272 .symver @var{name}, @var{name2@@@@@@nodename}
5274 When @var{name} is not defined within the
5275 file being assembled, it is treated as @var{name2@@nodename}. When
5276 @var{name} is defined within the file being assembled, the symbol
5277 name, @var{name}, will be changed to @var{name2@@@@nodename}.
5282 @section @code{.tag @var{structname}}
5284 @cindex COFF structure debugging
5285 @cindex structure debugging, COFF
5286 @cindex @code{tag} directive
5287 This directive is generated by compilers to include auxiliary debugging
5288 information in the symbol table. It is only permitted inside
5289 @code{.def}/@code{.endef} pairs. Tags are used to link structure
5290 definitions in the symbol table with instances of those structures.
5293 @samp{.tag} is only used when generating COFF format output; when
5294 @code{@value{AS}} is generating @code{b.out}, it accepts this directive but
5300 @section @code{.text @var{subsection}}
5302 @cindex @code{text} directive
5303 Tells @code{@value{AS}} to assemble the following statements onto the end of
5304 the text subsection numbered @var{subsection}, which is an absolute
5305 expression. If @var{subsection} is omitted, subsection number zero
5309 @section @code{.title "@var{heading}"}
5311 @cindex @code{title} directive
5312 @cindex listing control: title line
5313 Use @var{heading} as the title (second line, immediately after the
5314 source file name and pagenumber) when generating assembly listings.
5316 This directive affects subsequent pages, as well as the current page if
5317 it appears within ten lines of the top of a page.
5320 @section @code{.type @var{int}} (COFF version)
5322 @cindex COFF symbol type
5323 @cindex symbol type, COFF
5324 @cindex @code{type} directive
5325 This directive, permitted only within @code{.def}/@code{.endef} pairs,
5326 records the integer @var{int} as the type attribute of a symbol table entry.
5329 @samp{.type} is associated only with COFF format output; when
5330 @code{@value{AS}} is configured for @code{b.out} output, it accepts this
5331 directive but ignores it.
5334 @section @code{.type @var{name} , @var{type description}} (ELF version)
5336 @cindex ELF symbol type
5337 @cindex symbol type, ELF
5338 @cindex @code{type} directive
5339 This directive is used to set the type of symbol @var{name} to be either a
5340 function symbol or an object symbol. There are five different syntaxes
5341 supported for the @var{type description} field, in order to provide
5342 compatibility with various other assemblers. The syntaxes supported are:
5345 .type <name>,#function
5346 .type <name>,#object
5348 .type <name>,@@function
5349 .type <name>,@@object
5351 .type <name>,%function
5352 .type <name>,%object
5354 .type <name>,"function"
5355 .type <name>,"object"
5357 .type <name> STT_FUNCTION
5358 .type <name> STT_OBJECT
5362 @section @code{.uleb128 @var{expressions}}
5364 @cindex @code{uleb128} directive
5365 @var{uleb128} stands for ``unsigned little endian base 128.'' This is a
5366 compact, variable length representation of numbers used by the DWARF
5367 symbolic debugging format. @xref{Sleb128,@code{.sleb128}}.
5371 @section @code{.val @var{addr}}
5373 @cindex @code{val} directive
5374 @cindex COFF value attribute
5375 @cindex value attribute, COFF
5376 This directive, permitted only within @code{.def}/@code{.endef} pairs,
5377 records the address @var{addr} as the value attribute of a symbol table
5381 @samp{.val} is used only for COFF output; when @code{@value{AS}} is
5382 configured for @code{b.out}, it accepts this directive but ignores it.
5388 @section @code{.version "@var{string}"}
5390 @cindex @code{.version}
5391 This directive creates a @code{.note} section and places into it an ELF
5392 formatted note of type NT_VERSION. The note's name is set to @code{string}.
5397 @section @code{.vtable_entry @var{table}, @var{offset}}
5399 @cindex @code{.vtable_entry}
5400 This directive finds or creates a symbol @code{table} and creates a
5401 @code{VTABLE_ENTRY} relocation for it with an addend of @code{offset}.
5404 @section @code{.vtable_inherit @var{child}, @var{parent}}
5406 @cindex @code{.vtable_inherit}
5407 This directive finds the symbol @code{child} and finds or creates the symbol
5408 @code{parent} and then creates a @code{VTABLE_INHERIT} relocation for the
5409 parent whose addend is the value of the child symbol. As a special case the
5410 parent name of @code{0} is treated as refering the @code{*ABS*} section.
5415 @section @code{.weak @var{names}}
5417 @cindex @code{.weak}
5418 This directive sets the weak attribute on the comma separated list of symbol
5419 @code{names}. If the symbols do not already exist, they will be created.
5423 @section @code{.word @var{expressions}}
5425 @cindex @code{word} directive
5426 This directive expects zero or more @var{expressions}, of any section,
5427 separated by commas.
5430 For each expression, @code{@value{AS}} emits a 32-bit number.
5433 For each expression, @code{@value{AS}} emits a 16-bit number.
5438 The size of the number emitted, and its byte order,
5439 depend on what target computer the assembly is for.
5442 @c on amd29k, i960, sparc the "special treatment to support compilers" doesn't
5443 @c happen---32-bit addressability, period; no long/short jumps.
5444 @ifset DIFF-TBL-KLUGE
5445 @cindex difference tables altered
5446 @cindex altered difference tables
5448 @emph{Warning: Special Treatment to support Compilers}
5452 Machines with a 32-bit address space, but that do less than 32-bit
5453 addressing, require the following special treatment. If the machine of
5454 interest to you does 32-bit addressing (or doesn't require it;
5455 @pxref{Machine Dependencies}), you can ignore this issue.
5458 In order to assemble compiler output into something that works,
5459 @code{@value{AS}} occasionally does strange things to @samp{.word} directives.
5460 Directives of the form @samp{.word sym1-sym2} are often emitted by
5461 compilers as part of jump tables. Therefore, when @code{@value{AS}} assembles a
5462 directive of the form @samp{.word sym1-sym2}, and the difference between
5463 @code{sym1} and @code{sym2} does not fit in 16 bits, @code{@value{AS}}
5464 creates a @dfn{secondary jump table}, immediately before the next label.
5465 This secondary jump table is preceded by a short-jump to the
5466 first byte after the secondary table. This short-jump prevents the flow
5467 of control from accidentally falling into the new table. Inside the
5468 table is a long-jump to @code{sym2}. The original @samp{.word}
5469 contains @code{sym1} minus the address of the long-jump to
5472 If there were several occurrences of @samp{.word sym1-sym2} before the
5473 secondary jump table, all of them are adjusted. If there was a
5474 @samp{.word sym3-sym4}, that also did not fit in sixteen bits, a
5475 long-jump to @code{sym4} is included in the secondary jump table,
5476 and the @code{.word} directives are adjusted to contain @code{sym3}
5477 minus the address of the long-jump to @code{sym4}; and so on, for as many
5478 entries in the original jump table as necessary.
5481 @emph{This feature may be disabled by compiling @code{@value{AS}} with the
5482 @samp{-DWORKING_DOT_WORD} option.} This feature is likely to confuse
5483 assembly language programmers.
5486 @c end DIFF-TBL-KLUGE
5489 @section Deprecated Directives
5491 @cindex deprecated directives
5492 @cindex obsolescent directives
5493 One day these directives won't work.
5494 They are included for compatibility with older assemblers.
5501 @node Machine Dependencies
5502 @chapter Machine Dependent Features
5504 @cindex machine dependencies
5505 The machine instruction sets are (almost by definition) different on
5506 each machine where @code{@value{AS}} runs. Floating point representations
5507 vary as well, and @code{@value{AS}} often supports a few additional
5508 directives or command-line options for compatibility with other
5509 assemblers on a particular platform. Finally, some versions of
5510 @code{@value{AS}} support special pseudo-instructions for branch
5513 This chapter discusses most of these differences, though it does not
5514 include details on any machine's instruction set. For details on that
5515 subject, see the hardware manufacturer's manual.
5519 * AMD29K-Dependent:: AMD 29K Dependent Features
5522 * ARC-Dependent:: ARC Dependent Features
5525 * ARM-Dependent:: ARM Dependent Features
5528 * D10V-Dependent:: D10V Dependent Features
5531 * D30V-Dependent:: D30V Dependent Features
5534 * H8/300-Dependent:: Hitachi H8/300 Dependent Features
5537 * H8/500-Dependent:: Hitachi H8/500 Dependent Features
5540 * HPPA-Dependent:: HPPA Dependent Features
5543 * ESA/390-Dependent:: IBM ESA/390 Dependent Features
5546 * i386-Dependent:: Intel 80386 and AMD x86-64 Dependent Features
5549 * i860-Dependent:: Intel 80860 Dependent Features
5552 * i960-Dependent:: Intel 80960 Dependent Features
5555 * M32R-Dependent:: M32R Dependent Features
5558 * M68K-Dependent:: M680x0 Dependent Features
5561 * M68HC11-Dependent:: M68HC11 and 68HC12 Dependent Features
5564 * M88K-Dependent:: M880x0 Dependent Features
5567 * MIPS-Dependent:: MIPS Dependent Features
5570 * SH-Dependent:: Hitachi SH Dependent Features
5573 * PDP-11-Dependent:: PDP-11 Dependent Features
5576 * PJ-Dependent:: picoJava Dependent Features
5579 * PPC-Dependent:: PowerPC Dependent Features
5582 * Sparc-Dependent:: SPARC Dependent Features
5585 * TIC54X-Dependent:: TI TMS320C54x Dependent Features
5588 * V850-Dependent:: V850 Dependent Features
5591 * Z8000-Dependent:: Z8000 Dependent Features
5594 * Vax-Dependent:: VAX Dependent Features
5601 @c The following major nodes are *sections* in the GENERIC version, *chapters*
5602 @c in single-cpu versions. This is mainly achieved by @lowersections. There is a
5603 @c peculiarity: to preserve cross-references, there must be a node called
5604 @c "Machine Dependencies". Hence the conditional nodenames in each
5605 @c major node below. Node defaulting in makeinfo requires adjacency of
5606 @c node and sectioning commands; hence the repetition of @chapter BLAH
5607 @c in both conditional blocks.
5614 @include c-a29k.texi
5623 @node Machine Dependencies
5624 @chapter Machine Dependent Features
5626 The machine instruction sets are different on each Hitachi chip family,
5627 and there are also some syntax differences among the families. This
5628 chapter describes the specific @code{@value{AS}} features for each
5632 * H8/300-Dependent:: Hitachi H8/300 Dependent Features
5633 * H8/500-Dependent:: Hitachi H8/500 Dependent Features
5634 * SH-Dependent:: Hitachi SH Dependent Features
5641 @include c-d10v.texi
5645 @include c-d30v.texi
5649 @include c-h8300.texi
5653 @include c-h8500.texi
5657 @include c-hppa.texi
5661 @include c-i370.texi
5665 @include c-i386.texi
5669 @include c-i860.texi
5673 @include c-i960.texi
5677 @include c-m32r.texi
5681 @include c-m68k.texi
5685 @include c-m68hc11.texi
5689 @include c-m88k.texi
5693 @include c-mips.texi
5697 @include c-ns32k.texi
5701 @include c-pdp11.texi
5717 @include c-sparc.texi
5721 @include c-tic54x.texi
5733 @include c-v850.texi
5737 @c reverse effect of @down at top of generic Machine-Dep chapter
5741 @node Reporting Bugs
5742 @chapter Reporting Bugs
5743 @cindex bugs in assembler
5744 @cindex reporting bugs in assembler
5746 Your bug reports play an essential role in making @code{@value{AS}} reliable.
5748 Reporting a bug may help you by bringing a solution to your problem, or it may
5749 not. But in any case the principal function of a bug report is to help the
5750 entire community by making the next version of @code{@value{AS}} work better.
5751 Bug reports are your contribution to the maintenance of @code{@value{AS}}.
5753 In order for a bug report to serve its purpose, you must include the
5754 information that enables us to fix the bug.
5757 * Bug Criteria:: Have you found a bug?
5758 * Bug Reporting:: How to report bugs
5762 @section Have you found a bug?
5763 @cindex bug criteria
5765 If you are not sure whether you have found a bug, here are some guidelines:
5768 @cindex fatal signal
5769 @cindex assembler crash
5770 @cindex crash of assembler
5772 If the assembler gets a fatal signal, for any input whatever, that is a
5773 @code{@value{AS}} bug. Reliable assemblers never crash.
5775 @cindex error on valid input
5777 If @code{@value{AS}} produces an error message for valid input, that is a bug.
5779 @cindex invalid input
5781 If @code{@value{AS}} does not produce an error message for invalid input, that
5782 is a bug. However, you should note that your idea of ``invalid input'' might
5783 be our idea of ``an extension'' or ``support for traditional practice''.
5786 If you are an experienced user of assemblers, your suggestions for improvement
5787 of @code{@value{AS}} are welcome in any case.
5791 @section How to report bugs
5793 @cindex assembler bugs, reporting
5795 A number of companies and individuals offer support for @sc{gnu} products. If
5796 you obtained @code{@value{AS}} from a support organization, we recommend you
5797 contact that organization first.
5799 You can find contact information for many support companies and
5800 individuals in the file @file{etc/SERVICE} in the @sc{gnu} Emacs
5803 In any event, we also recommend that you send bug reports for @code{@value{AS}}
5804 to @samp{bug-binutils@@gnu.org}.
5806 The fundamental principle of reporting bugs usefully is this:
5807 @strong{report all the facts}. If you are not sure whether to state a
5808 fact or leave it out, state it!
5810 Often people omit facts because they think they know what causes the problem
5811 and assume that some details do not matter. Thus, you might assume that the
5812 name of a symbol you use in an example does not matter. Well, probably it does
5813 not, but one cannot be sure. Perhaps the bug is a stray memory reference which
5814 happens to fetch from the location where that name is stored in memory;
5815 perhaps, if the name were different, the contents of that location would fool
5816 the assembler into doing the right thing despite the bug. Play it safe and
5817 give a specific, complete example. That is the easiest thing for you to do,
5818 and the most helpful.
5820 Keep in mind that the purpose of a bug report is to enable us to fix the bug if
5821 it is new to us. Therefore, always write your bug reports on the assumption
5822 that the bug has not been reported previously.
5824 Sometimes people give a few sketchy facts and ask, ``Does this ring a
5825 bell?'' Those bug reports are useless, and we urge everyone to
5826 @emph{refuse to respond to them} except to chide the sender to report
5829 To enable us to fix the bug, you should include all these things:
5833 The version of @code{@value{AS}}. @code{@value{AS}} announces it if you start
5834 it with the @samp{--version} argument.
5836 Without this, we will not know whether there is any point in looking for
5837 the bug in the current version of @code{@value{AS}}.
5840 Any patches you may have applied to the @code{@value{AS}} source.
5843 The type of machine you are using, and the operating system name and
5847 What compiler (and its version) was used to compile @code{@value{AS}}---e.g.
5851 The command arguments you gave the assembler to assemble your example and
5852 observe the bug. To guarantee you will not omit something important, list them
5853 all. A copy of the Makefile (or the output from make) is sufficient.
5855 If we were to try to guess the arguments, we would probably guess wrong
5856 and then we might not encounter the bug.
5859 A complete input file that will reproduce the bug. If the bug is observed when
5860 the assembler is invoked via a compiler, send the assembler source, not the
5861 high level language source. Most compilers will produce the assembler source
5862 when run with the @samp{-S} option. If you are using @code{@value{GCC}}, use
5863 the options @samp{-v --save-temps}; this will save the assembler source in a
5864 file with an extension of @file{.s}, and also show you exactly how
5865 @code{@value{AS}} is being run.
5868 A description of what behavior you observe that you believe is
5869 incorrect. For example, ``It gets a fatal signal.''
5871 Of course, if the bug is that @code{@value{AS}} gets a fatal signal, then we
5872 will certainly notice it. But if the bug is incorrect output, we might not
5873 notice unless it is glaringly wrong. You might as well not give us a chance to
5876 Even if the problem you experience is a fatal signal, you should still say so
5877 explicitly. Suppose something strange is going on, such as, your copy of
5878 @code{@value{AS}} is out of synch, or you have encountered a bug in the C
5879 library on your system. (This has happened!) Your copy might crash and ours
5880 would not. If you told us to expect a crash, then when ours fails to crash, we
5881 would know that the bug was not happening for us. If you had not told us to
5882 expect a crash, then we would not be able to draw any conclusion from our
5886 If you wish to suggest changes to the @code{@value{AS}} source, send us context
5887 diffs, as generated by @code{diff} with the @samp{-u}, @samp{-c}, or @samp{-p}
5888 option. Always send diffs from the old file to the new file. If you even
5889 discuss something in the @code{@value{AS}} source, refer to it by context, not
5892 The line numbers in our development sources will not match those in your
5893 sources. Your line numbers would convey no useful information to us.
5896 Here are some things that are not necessary:
5900 A description of the envelope of the bug.
5902 Often people who encounter a bug spend a lot of time investigating
5903 which changes to the input file will make the bug go away and which
5904 changes will not affect it.
5906 This is often time consuming and not very useful, because the way we
5907 will find the bug is by running a single example under the debugger
5908 with breakpoints, not by pure deduction from a series of examples.
5909 We recommend that you save your time for something else.
5911 Of course, if you can find a simpler example to report @emph{instead}
5912 of the original one, that is a convenience for us. Errors in the
5913 output will be easier to spot, running under the debugger will take
5914 less time, and so on.
5916 However, simplification is not vital; if you do not want to do this,
5917 report the bug anyway and send us the entire test case you used.
5920 A patch for the bug.
5922 A patch for the bug does help us if it is a good one. But do not omit
5923 the necessary information, such as the test case, on the assumption that
5924 a patch is all we need. We might see problems with your patch and decide
5925 to fix the problem another way, or we might not understand it at all.
5927 Sometimes with a program as complicated as @code{@value{AS}} it is very hard to
5928 construct an example that will make the program follow a certain path through
5929 the code. If you do not send us the example, we will not be able to construct
5930 one, so we will not be able to verify that the bug is fixed.
5932 And if we cannot understand what bug you are trying to fix, or why your
5933 patch should be an improvement, we will not install it. A test case will
5934 help us to understand.
5937 A guess about what the bug is or what it depends on.
5939 Such guesses are usually wrong. Even we cannot guess right about such
5940 things without first using the debugger to find the facts.
5943 @node Acknowledgements
5944 @chapter Acknowledgements
5946 If you have contributed to @code{@value{AS}} and your name isn't listed here,
5947 it is not meant as a slight. We just don't know about it. Send mail to the
5948 maintainer, and we'll correct the situation. Currently
5950 the maintainer is Ken Raeburn (email address @code{raeburn@@cygnus.com}).
5952 Dean Elsner wrote the original @sc{gnu} assembler for the VAX.@footnote{Any
5955 Jay Fenlason maintained GAS for a while, adding support for GDB-specific debug
5956 information and the 68k series machines, most of the preprocessing pass, and
5957 extensive changes in @file{messages.c}, @file{input-file.c}, @file{write.c}.
5959 K. Richard Pixley maintained GAS for a while, adding various enhancements and
5960 many bug fixes, including merging support for several processors, breaking GAS
5961 up to handle multiple object file format back ends (including heavy rewrite,
5962 testing, an integration of the coff and b.out back ends), adding configuration
5963 including heavy testing and verification of cross assemblers and file splits
5964 and renaming, converted GAS to strictly ANSI C including full prototypes, added
5965 support for m680[34]0 and cpu32, did considerable work on i960 including a COFF
5966 port (including considerable amounts of reverse engineering), a SPARC opcode
5967 file rewrite, DECstation, rs6000, and hp300hpux host ports, updated ``know''
5968 assertions and made them work, much other reorganization, cleanup, and lint.
5970 Ken Raeburn wrote the high-level BFD interface code to replace most of the code
5971 in format-specific I/O modules.
5973 The original VMS support was contributed by David L. Kashtan. Eric Youngdale
5974 has done much work with it since.
5976 The Intel 80386 machine description was written by Eliot Dresselhaus.
5978 Minh Tran-Le at IntelliCorp contributed some AIX 386 support.
5980 The Motorola 88k machine description was contributed by Devon Bowen of Buffalo
5981 University and Torbjorn Granlund of the Swedish Institute of Computer Science.
5983 Keith Knowles at the Open Software Foundation wrote the original MIPS back end
5984 (@file{tc-mips.c}, @file{tc-mips.h}), and contributed Rose format support
5985 (which hasn't been merged in yet). Ralph Campbell worked with the MIPS code to
5986 support a.out format.
5988 Support for the Zilog Z8k and Hitachi H8/300 and H8/500 processors (tc-z8k,
5989 tc-h8300, tc-h8500), and IEEE 695 object file format (obj-ieee), was written by
5990 Steve Chamberlain of Cygnus Support. Steve also modified the COFF back end to
5991 use BFD for some low-level operations, for use with the H8/300 and AMD 29k
5994 John Gilmore built the AMD 29000 support, added @code{.include} support, and
5995 simplified the configuration of which versions accept which directives. He
5996 updated the 68k machine description so that Motorola's opcodes always produced
5997 fixed-size instructions (e.g. @code{jsr}), while synthetic instructions
5998 remained shrinkable (@code{jbsr}). John fixed many bugs, including true tested
5999 cross-compilation support, and one bug in relaxation that took a week and
6000 required the proverbial one-bit fix.
6002 Ian Lance Taylor of Cygnus Support merged the Motorola and MIT syntax for the
6003 68k, completed support for some COFF targets (68k, i386 SVR3, and SCO Unix),
6004 added support for MIPS ECOFF and ELF targets, wrote the initial RS/6000 and
6005 PowerPC assembler, and made a few other minor patches.
6007 Steve Chamberlain made @code{@value{AS}} able to generate listings.
6009 Hewlett-Packard contributed support for the HP9000/300.
6011 Jeff Law wrote GAS and BFD support for the native HPPA object format (SOM)
6012 along with a fairly extensive HPPA testsuite (for both SOM and ELF object
6013 formats). This work was supported by both the Center for Software Science at
6014 the University of Utah and Cygnus Support.
6016 Support for ELF format files has been worked on by Mark Eichin of Cygnus
6017 Support (original, incomplete implementation for SPARC), Pete Hoogenboom and
6018 Jeff Law at the University of Utah (HPPA mainly), Michael Meissner of the Open
6019 Software Foundation (i386 mainly), and Ken Raeburn of Cygnus Support (sparc,
6020 and some initial 64-bit support).
6022 Linas Vepstas added GAS support for the ESA/390 "IBM 370" architecture.
6024 Richard Henderson rewrote the Alpha assembler. Klaus Kaempf wrote GAS and BFD
6025 support for openVMS/Alpha.
6027 Timothy Wall, Michael Hayes, and Greg Smart contributed to the various tic*
6030 Several engineers at Cygnus Support have also provided many small bug fixes and
6031 configuration enhancements.
6033 Many others have contributed large or small bugfixes and enhancements. If
6034 you have contributed significant work and are not mentioned on this list, and
6035 want to be, let us know. Some of the history has been lost; we are not
6036 intentionally leaving anyone out.
6038 @node GNU Free Documentation License
6039 @chapter GNU Free Documentation License
6041 GNU Free Documentation License
6043 Version 1.1, March 2000
6045 Copyright (C) 2000 Free Software Foundation, Inc.
6046 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
6048 Everyone is permitted to copy and distribute verbatim copies
6049 of this license document, but changing it is not allowed.
6054 The purpose of this License is to make a manual, textbook, or other
6055 written document "free" in the sense of freedom: to assure everyone
6056 the effective freedom to copy and redistribute it, with or without
6057 modifying it, either commercially or noncommercially. Secondarily,
6058 this License preserves for the author and publisher a way to get
6059 credit for their work, while not being considered responsible for
6060 modifications made by others.
6062 This License is a kind of "copyleft", which means that derivative
6063 works of the document must themselves be free in the same sense. It
6064 complements the GNU General Public License, which is a copyleft
6065 license designed for free software.
6067 We have designed this License in order to use it for manuals for free
6068 software, because free software needs free documentation: a free
6069 program should come with manuals providing the same freedoms that the
6070 software does. But this License is not limited to software manuals;
6071 it can be used for any textual work, regardless of subject matter or
6072 whether it is published as a printed book. We recommend this License
6073 principally for works whose purpose is instruction or reference.
6076 1. APPLICABILITY AND DEFINITIONS
6078 This License applies to any manual or other work that contains a
6079 notice placed by the copyright holder saying it can be distributed
6080 under the terms of this License. The "Document", below, refers to any
6081 such manual or work. Any member of the public is a licensee, and is
6084 A "Modified Version" of the Document means any work containing the
6085 Document or a portion of it, either copied verbatim, or with
6086 modifications and/or translated into another language.
6088 A "Secondary Section" is a named appendix or a front-matter section of
6089 the Document that deals exclusively with the relationship of the
6090 publishers or authors of the Document to the Document's overall subject
6091 (or to related matters) and contains nothing that could fall directly
6092 within that overall subject. (For example, if the Document is in part a
6093 textbook of mathematics, a Secondary Section may not explain any
6094 mathematics.) The relationship could be a matter of historical
6095 connection with the subject or with related matters, or of legal,
6096 commercial, philosophical, ethical or political position regarding
6099 The "Invariant Sections" are certain Secondary Sections whose titles
6100 are designated, as being those of Invariant Sections, in the notice
6101 that says that the Document is released under this License.
6103 The "Cover Texts" are certain short passages of text that are listed,
6104 as Front-Cover Texts or Back-Cover Texts, in the notice that says that
6105 the Document is released under this License.
6107 A "Transparent" copy of the Document means a machine-readable copy,
6108 represented in a format whose specification is available to the
6109 general public, whose contents can be viewed and edited directly and
6110 straightforwardly with generic text editors or (for images composed of
6111 pixels) generic paint programs or (for drawings) some widely available
6112 drawing editor, and that is suitable for input to text formatters or
6113 for automatic translation to a variety of formats suitable for input
6114 to text formatters. A copy made in an otherwise Transparent file
6115 format whose markup has been designed to thwart or discourage
6116 subsequent modification by readers is not Transparent. A copy that is
6117 not "Transparent" is called "Opaque".
6119 Examples of suitable formats for Transparent copies include plain
6120 ASCII without markup, Texinfo input format, LaTeX input format, SGML
6121 or XML using a publicly available DTD, and standard-conforming simple
6122 HTML designed for human modification. Opaque formats include
6123 PostScript, PDF, proprietary formats that can be read and edited only
6124 by proprietary word processors, SGML or XML for which the DTD and/or
6125 processing tools are not generally available, and the
6126 machine-generated HTML produced by some word processors for output
6129 The "Title Page" means, for a printed book, the title page itself,
6130 plus such following pages as are needed to hold, legibly, the material
6131 this License requires to appear in the title page. For works in
6132 formats which do not have any title page as such, "Title Page" means
6133 the text near the most prominent appearance of the work's title,
6134 preceding the beginning of the body of the text.
6139 You may copy and distribute the Document in any medium, either
6140 commercially or noncommercially, provided that this License, the
6141 copyright notices, and the license notice saying this License applies
6142 to the Document are reproduced in all copies, and that you add no other
6143 conditions whatsoever to those of this License. You may not use
6144 technical measures to obstruct or control the reading or further
6145 copying of the copies you make or distribute. However, you may accept
6146 compensation in exchange for copies. If you distribute a large enough
6147 number of copies you must also follow the conditions in section 3.
6149 You may also lend copies, under the same conditions stated above, and
6150 you may publicly display copies.
6153 3. COPYING IN QUANTITY
6155 If you publish printed copies of the Document numbering more than 100,
6156 and the Document's license notice requires Cover Texts, you must enclose
6157 the copies in covers that carry, clearly and legibly, all these Cover
6158 Texts: Front-Cover Texts on the front cover, and Back-Cover Texts on
6159 the back cover. Both covers must also clearly and legibly identify
6160 you as the publisher of these copies. The front cover must present
6161 the full title with all words of the title equally prominent and
6162 visible. You may add other material on the covers in addition.
6163 Copying with changes limited to the covers, as long as they preserve
6164 the title of the Document and satisfy these conditions, can be treated
6165 as verbatim copying in other respects.
6167 If the required texts for either cover are too voluminous to fit
6168 legibly, you should put the first ones listed (as many as fit
6169 reasonably) on the actual cover, and continue the rest onto adjacent
6172 If you publish or distribute Opaque copies of the Document numbering
6173 more than 100, you must either include a machine-readable Transparent
6174 copy along with each Opaque copy, or state in or with each Opaque copy
6175 a publicly-accessible computer-network location containing a complete
6176 Transparent copy of the Document, free of added material, which the
6177 general network-using public has access to download anonymously at no
6178 charge using public-standard network protocols. If you use the latter
6179 option, you must take reasonably prudent steps, when you begin
6180 distribution of Opaque copies in quantity, to ensure that this
6181 Transparent copy will remain thus accessible at the stated location
6182 until at least one year after the last time you distribute an Opaque
6183 copy (directly or through your agents or retailers) of that edition to
6186 It is requested, but not required, that you contact the authors of the
6187 Document well before redistributing any large number of copies, to give
6188 them a chance to provide you with an updated version of the Document.
6193 You may copy and distribute a Modified Version of the Document under
6194 the conditions of sections 2 and 3 above, provided that you release
6195 the Modified Version under precisely this License, with the Modified
6196 Version filling the role of the Document, thus licensing distribution
6197 and modification of the Modified Version to whoever possesses a copy
6198 of it. In addition, you must do these things in the Modified Version:
6200 A. Use in the Title Page (and on the covers, if any) a title distinct
6201 from that of the Document, and from those of previous versions
6202 (which should, if there were any, be listed in the History section
6203 of the Document). You may use the same title as a previous version
6204 if the original publisher of that version gives permission.
6205 B. List on the Title Page, as authors, one or more persons or entities
6206 responsible for authorship of the modifications in the Modified
6207 Version, together with at least five of the principal authors of the
6208 Document (all of its principal authors, if it has less than five).
6209 C. State on the Title page the name of the publisher of the
6210 Modified Version, as the publisher.
6211 D. Preserve all the copyright notices of the Document.
6212 E. Add an appropriate copyright notice for your modifications
6213 adjacent to the other copyright notices.
6214 F. Include, immediately after the copyright notices, a license notice
6215 giving the public permission to use the Modified Version under the
6216 terms of this License, in the form shown in the Addendum below.
6217 G. Preserve in that license notice the full lists of Invariant Sections
6218 and required Cover Texts given in the Document's license notice.
6219 H. Include an unaltered copy of this License.
6220 I. Preserve the section entitled "History", and its title, and add to
6221 it an item stating at least the title, year, new authors, and
6222 publisher of the Modified Version as given on the Title Page. If
6223 there is no section entitled "History" in the Document, create one
6224 stating the title, year, authors, and publisher of the Document as
6225 given on its Title Page, then add an item describing the Modified
6226 Version as stated in the previous sentence.
6227 J. Preserve the network location, if any, given in the Document for
6228 public access to a Transparent copy of the Document, and likewise
6229 the network locations given in the Document for previous versions
6230 it was based on. These may be placed in the "History" section.
6231 You may omit a network location for a work that was published at
6232 least four years before the Document itself, or if the original
6233 publisher of the version it refers to gives permission.
6234 K. In any section entitled "Acknowledgements" or "Dedications",
6235 preserve the section's title, and preserve in the section all the
6236 substance and tone of each of the contributor acknowledgements
6237 and/or dedications given therein.
6238 L. Preserve all the Invariant Sections of the Document,
6239 unaltered in their text and in their titles. Section numbers
6240 or the equivalent are not considered part of the section titles.
6241 M. Delete any section entitled "Endorsements". Such a section
6242 may not be included in the Modified Version.
6243 N. Do not retitle any existing section as "Endorsements"
6244 or to conflict in title with any Invariant Section.
6246 If the Modified Version includes new front-matter sections or
6247 appendices that qualify as Secondary Sections and contain no material
6248 copied from the Document, you may at your option designate some or all
6249 of these sections as invariant. To do this, add their titles to the
6250 list of Invariant Sections in the Modified Version's license notice.
6251 These titles must be distinct from any other section titles.
6253 You may add a section entitled "Endorsements", provided it contains
6254 nothing but endorsements of your Modified Version by various
6255 parties--for example, statements of peer review or that the text has
6256 been approved by an organization as the authoritative definition of a
6259 You may add a passage of up to five words as a Front-Cover Text, and a
6260 passage of up to 25 words as a Back-Cover Text, to the end of the list
6261 of Cover Texts in the Modified Version. Only one passage of
6262 Front-Cover Text and one of Back-Cover Text may be added by (or
6263 through arrangements made by) any one entity. If the Document already
6264 includes a cover text for the same cover, previously added by you or
6265 by arrangement made by the same entity you are acting on behalf of,
6266 you may not add another; but you may replace the old one, on explicit
6267 permission from the previous publisher that added the old one.
6269 The author(s) and publisher(s) of the Document do not by this License
6270 give permission to use their names for publicity for or to assert or
6271 imply endorsement of any Modified Version.
6274 5. COMBINING DOCUMENTS
6276 You may combine the Document with other documents released under this
6277 License, under the terms defined in section 4 above for modified
6278 versions, provided that you include in the combination all of the
6279 Invariant Sections of all of the original documents, unmodified, and
6280 list them all as Invariant Sections of your combined work in its
6283 The combined work need only contain one copy of this License, and
6284 multiple identical Invariant Sections may be replaced with a single
6285 copy. If there are multiple Invariant Sections with the same name but
6286 different contents, make the title of each such section unique by
6287 adding at the end of it, in parentheses, the name of the original
6288 author or publisher of that section if known, or else a unique number.
6289 Make the same adjustment to the section titles in the list of
6290 Invariant Sections in the license notice of the combined work.
6292 In the combination, you must combine any sections entitled "History"
6293 in the various original documents, forming one section entitled
6294 "History"; likewise combine any sections entitled "Acknowledgements",
6295 and any sections entitled "Dedications". You must delete all sections
6296 entitled "Endorsements."
6299 6. COLLECTIONS OF DOCUMENTS
6301 You may make a collection consisting of the Document and other documents
6302 released under this License, and replace the individual copies of this
6303 License in the various documents with a single copy that is included in
6304 the collection, provided that you follow the rules of this License for
6305 verbatim copying of each of the documents in all other respects.
6307 You may extract a single document from such a collection, and distribute
6308 it individually under this License, provided you insert a copy of this
6309 License into the extracted document, and follow this License in all
6310 other respects regarding verbatim copying of that document.
6313 7. AGGREGATION WITH INDEPENDENT WORKS
6315 A compilation of the Document or its derivatives with other separate
6316 and independent documents or works, in or on a volume of a storage or
6317 distribution medium, does not as a whole count as a Modified Version
6318 of the Document, provided no compilation copyright is claimed for the
6319 compilation. Such a compilation is called an "aggregate", and this
6320 License does not apply to the other self-contained works thus compiled
6321 with the Document, on account of their being thus compiled, if they
6322 are not themselves derivative works of the Document.
6324 If the Cover Text requirement of section 3 is applicable to these
6325 copies of the Document, then if the Document is less than one quarter
6326 of the entire aggregate, the Document's Cover Texts may be placed on
6327 covers that surround only the Document within the aggregate.
6328 Otherwise they must appear on covers around the whole aggregate.
6333 Translation is considered a kind of modification, so you may
6334 distribute translations of the Document under the terms of section 4.
6335 Replacing Invariant Sections with translations requires special
6336 permission from their copyright holders, but you may include
6337 translations of some or all Invariant Sections in addition to the
6338 original versions of these Invariant Sections. You may include a
6339 translation of this License provided that you also include the
6340 original English version of this License. In case of a disagreement
6341 between the translation and the original English version of this
6342 License, the original English version will prevail.
6347 You may not copy, modify, sublicense, or distribute the Document except
6348 as expressly provided for under this License. Any other attempt to
6349 copy, modify, sublicense or distribute the Document is void, and will
6350 automatically terminate your rights under this License. However,
6351 parties who have received copies, or rights, from you under this
6352 License will not have their licenses terminated so long as such
6353 parties remain in full compliance.
6356 10. FUTURE REVISIONS OF THIS LICENSE
6358 The Free Software Foundation may publish new, revised versions
6359 of the GNU Free Documentation License from time to time. Such new
6360 versions will be similar in spirit to the present version, but may
6361 differ in detail to address new problems or concerns. See
6362 http://www.gnu.org/copyleft/.
6364 Each version of the License is given a distinguishing version number.
6365 If the Document specifies that a particular numbered version of this
6366 License "or any later version" applies to it, you have the option of
6367 following the terms and conditions either of that specified version or
6368 of any later version that has been published (not as a draft) by the
6369 Free Software Foundation. If the Document does not specify a version
6370 number of this License, you may choose any version ever published (not
6371 as a draft) by the Free Software Foundation.
6374 ADDENDUM: How to use this License for your documents
6376 To use this License in a document you have written, include a copy of
6377 the License in the document and put the following copyright and
6378 license notices just after the title page:
6381 Copyright (c) YEAR YOUR NAME.
6382 Permission is granted to copy, distribute and/or modify this document
6383 under the terms of the GNU Free Documentation License, Version 1.1
6384 or any later version published by the Free Software Foundation;
6385 with the Invariant Sections being LIST THEIR TITLES, with the
6386 Front-Cover Texts being LIST, and with the Back-Cover Texts being LIST.
6387 A copy of the license is included in the section entitled "GNU
6388 Free Documentation License".
6391 If you have no Invariant Sections, write "with no Invariant Sections"
6392 instead of saying which ones are invariant. If you have no
6393 Front-Cover Texts, write "no Front-Cover Texts" instead of
6394 "Front-Cover Texts being LIST"; likewise for Back-Cover Texts.
6396 If your document contains nontrivial examples of program code, we
6397 recommend releasing these examples in parallel under your choice of
6398 free software license, such as the GNU General Public License,
6399 to permit their use in free software.
projects / external / binutils.git / blob