1 \input texinfo @c -*-Texinfo-*-
2 @c Copyright (c) 1991, 92, 93, 94, 95, 96, 97, 98, 2000
3 @c Free Software Foundation, Inc.
4 @c UPDATE!! On future updates--
5 @c (1) check for new machine-dep cmdline options in
6 @c md_parse_option definitions in config/tc-*.c
7 @c (2) for platform-specific directives, examine md_pseudo_op
9 @c (3) for object-format specific directives, examine obj_pseudo_op
11 @c (4) portable directives in potable[] in read.c
15 @c defaults, config file may override:
18 @include asconfig.texi
21 @c common OR combinations of conditions
41 @set abnormal-separator
45 @settitle Using @value{AS}
48 @settitle Using @value{AS} (@value{TARGET})
50 @setchapternewpage odd
55 @c WARE! Some of the machine-dependent sections contain tables of machine
56 @c instructions. Except in multi-column format, these tables look silly.
57 @c Unfortunately, Texinfo doesn't have a general-purpose multi-col format, so
58 @c the multi-col format is faked within @example sections.
60 @c Again unfortunately, the natural size that fits on a page, for these tables,
61 @c is different depending on whether or not smallbook is turned on.
62 @c This matters, because of order: text flow switches columns at each page
65 @c The format faked in this source works reasonably well for smallbook,
66 @c not well for the default large-page format. This manual expects that if you
67 @c turn on @smallbook, you will also uncomment the "@set SMALL" to enable the
68 @c tables in question. You can turn on one without the other at your
69 @c discretion, of course.
72 @c the insn tables look just as silly in info files regardless of smallbook,
73 @c might as well show 'em anyways.
79 * As: (as). The GNU assembler.
88 This file documents the GNU Assembler "@value{AS}".
90 Copyright (C) 1991, 92, 93, 94, 95, 96, 97, 98, 99, 2000 Free Software Foundation, Inc.
92 Permission is granted to make and distribute verbatim copies of
93 this manual provided the copyright notice and this permission notice
94 are preserved on all copies.
97 Permission is granted to process this file through Tex and print the
98 results, provided the printed document carries copying permission
99 notice identical to this one except for the removal of this paragraph
100 (this paragraph not being relevant to the printed manual).
103 Permission is granted to copy and distribute modified versions of this manual
104 under the conditions for verbatim copying, provided that the entire resulting
105 derived work is distributed under the terms of a permission notice identical to
108 Permission is granted to copy and distribute translations of this manual
109 into another language, under the above conditions for modified versions.
113 @title Using @value{AS}
114 @subtitle The @sc{gnu} Assembler
116 @subtitle for the @value{TARGET} family
119 @subtitle Version @value{VERSION}
122 The Free Software Foundation Inc. thanks The Nice Computer
123 Company of Australia for loaning Dean Elsner to write the
124 first (Vax) version of @code{as} for Project @sc{gnu}.
125 The proprietors, management and staff of TNCCA thank FSF for
126 distracting the boss while they got some work
129 @author Dean Elsner, Jay Fenlason & friends
133 \hfill {\it Using {\tt @value{AS}}}\par
134 \hfill Edited by Cygnus Support\par
136 %"boxit" macro for figures:
137 %Modified from Knuth's ``boxit'' macro from TeXbook (answer to exercise 21.3)
138 \gdef\boxit#1#2{\vbox{\hrule\hbox{\vrule\kern3pt
139 \vbox{\parindent=0pt\parskip=0pt\hsize=#1\kern3pt\strut\hfil
140 #2\hfil\strut\kern3pt}\kern3pt\vrule}\hrule}}%box with visible outline
141 \gdef\ibox#1#2{\hbox to #1{#2\hfil}\kern8pt}% invisible box
144 @vskip 0pt plus 1filll
145 Copyright @copyright{} 1991, 92, 93, 94, 95, 96, 97, 98, 99, 2000 Free Software Foundation, Inc.
147 Permission is granted to make and distribute verbatim copies of
148 this manual provided the copyright notice and this permission notice
149 are preserved on all copies.
151 Permission is granted to copy and distribute modified versions of this manual
152 under the conditions for verbatim copying, provided that the entire resulting
153 derived work is distributed under the terms of a permission notice identical to
156 Permission is granted to copy and distribute translations of this manual
157 into another language, under the above conditions for modified versions.
162 @top Using @value{AS}
164 This file is a user guide to the @sc{gnu} assembler @code{@value{AS}} version
167 This version of the file describes @code{@value{AS}} configured to generate
168 code for @value{TARGET} architectures.
171 * Overview:: Overview
172 * Invoking:: Command-Line Options
174 * Sections:: Sections and Relocation
176 * Expressions:: Expressions
177 * Pseudo Ops:: Assembler Directives
178 * Machine Dependencies:: Machine Dependent Features
179 * Reporting Bugs:: Reporting Bugs
180 * Acknowledgements:: Who Did What
188 This manual is a user guide to the @sc{gnu} assembler @code{@value{AS}}.
190 This version of the manual describes @code{@value{AS}} configured to generate
191 code for @value{TARGET} architectures.
195 @cindex invocation summary
196 @cindex option summary
197 @cindex summary of options
198 Here is a brief summary of how to invoke @code{@value{AS}}. For details,
199 @pxref{Invoking,,Comand-Line Options}.
201 @c We don't use deffn and friends for the following because they seem
202 @c to be limited to one line for the header.
204 @value{AS} [ -a[cdhlns][=file] ] [ -D ] [ --defsym @var{sym}=@var{val} ]
205 [ -f ] [ --gstabs ] [ --gdwarf2 ] [ --help ] [ -I @var{dir} ] [ -J ] [ -K ] [ -L ]
206 [ --keep-locals ] [ -o @var{objfile} ] [ -R ] [ --statistics ] [ -v ]
207 [ -version ] [ --version ] [ -W ] [ --warn ] [ --fatal-warnings ]
210 @c am29k has no machine-dependent assembler options
213 [ -mbig-endian | -mlittle-endian ]
216 [ -m[arm]1 | -m[arm]2 | -m[arm]250 | -m[arm]3 | -m[arm]6 | -m[arm]60 |
217 -m[arm]600 | -m[arm]610 | -m[arm]620 | -m[arm]7[t][[d]m[i]][fe] | -m[arm]70 |
218 -m[arm]700 | -m[arm]710[c] | -m[arm]7100 | -m[arm]7500 | -m[arm]8 |
219 -m[arm]810 | -m[arm]9 | -m[arm]920 | -m[arm]920t | -m[arm]9tdmi |
220 -mstrongarm | -mstrongarm110 | -mstrongarm1100 ]
221 [ -m[arm]v2 | -m[arm]v2a | -m[arm]v3 | -m[arm]v3m | -m[arm]v4 | -m[arm]v4t |
222 -m[arm]v5 | -[arm]v5t ]
224 [ -mfpa10 | -mfpa11 | -mfpe-old | -mno-fpu ]
226 [ -mapcs-32 | -mapcs-26 | -mapcs-float | -mapcs-reentrant ]
227 [ -mthumb-interwork ]
238 @c Hitachi family chips have no machine-dependent assembler options
241 @c HPPA has no machine-dependent assembler options (yet).
247 @c The order here is important. See c-sparc.texi.
248 [ -Av6 | -Av7 | -Av8 | -Asparclet | -Asparclite
249 -Av8plus | -Av8plusa | -Av9 | -Av9a ]
250 [ -xarch=v8plus | -xarch=v8plusa ] [ -bump ] [ -32 | -64 ]
253 [ -mcpu=54[123589] | -mcpu=54[56]lp ] [ -mfar-mode | -mf ]
254 [ -merrors-to-file <filename> | -me <filename> ]
257 @c Z8000 has no machine-dependent assembler options
260 @c see md_parse_option in tc-i960.c
261 [ -ACA | -ACA_A | -ACB | -ACC | -AKA | -AKB | -AKC | -AMC ]
265 [ --m32rx | --[no-]warn-explicit-parallel-conflicts | --W[n]p ]
268 [ -l ] [ -m68000 | -m68010 | -m68020 | ... ]
271 [ -jsri2bsr ] [ -sifilter ] [ -relax ]
275 [ -m68hc11 | -m68hc12 ]
276 [ --force-long-branchs ] [ --short-branchs ] [ --strict-direct-mode ]
277 [ --print-insn-syntax ] [ --print-opcodes ] [ --generate-example ]
280 [ -nocpp ] [ -EL ] [ -EB ] [ -G @var{num} ] [ -mcpu=@var{CPU} ]
281 [ -mips1 ] [ -mips2 ] [ -mips3 ] [ -m4650 ] [ -no-m4650 ] [ -mips32 ] [ -no-mips32 ]
282 [ --trap ] [ --break ]
283 [ --emulation=@var{name} ]
285 [ -- | @var{files} @dots{} ]
290 Turn on listings, in any of a variety of ways:
294 omit false conditionals
297 omit debugging directives
300 include high-level source
306 include macro expansions
309 omit forms processing
315 set the name of the listing file
318 You may combine these options; for example, use @samp{-aln} for assembly
319 listing without forms processing. The @samp{=file} option, if used, must be
320 the last one. By itself, @samp{-a} defaults to @samp{-ahls}.
323 Ignored. This option is accepted for script compatibility with calls to
326 @item --defsym @var{sym}=@var{value}
327 Define the symbol @var{sym} to be @var{value} before assembling the input file.
328 @var{value} must be an integer constant. As in C, a leading @samp{0x}
329 indicates a hexadecimal value, and a leading @samp{0} indicates an octal value.
332 ``fast''---skip whitespace and comment preprocessing (assume source is
336 Generate stabs debugging information for each assembler line. This
337 may help debugging assembler code, if the debugger can handle it.
340 Generate DWARF2 debugging information for each assembler line. This
341 may help debugging assembler code, if the debugger can handle it.
344 Print a summary of the command line options and exit.
347 Add directory @var{dir} to the search list for @code{.include} directives.
350 Don't warn about signed overflow.
353 @ifclear DIFF-TBL-KLUGE
354 This option is accepted but has no effect on the @value{TARGET} family.
356 @ifset DIFF-TBL-KLUGE
357 Issue warnings when difference tables altered for long displacements.
362 Keep (in the symbol table) local symbols. On traditional a.out systems
363 these start with @samp{L}, but different systems have different local
366 @item -o @var{objfile}
367 Name the object-file output from @code{@value{AS}} @var{objfile}.
370 Fold the data section into the text section.
373 Print the maximum space (in bytes) and total time (in seconds) used by
376 @item --strip-local-absolute
377 Remove local absolute symbols from the outgoing symbol table.
381 Print the @code{as} version.
384 Print the @code{as} version and exit.
388 Suppress warning messages.
390 @item --fatal-warnings
391 Treat warnings as errors.
394 Don't suppress warning messages or treat them as errors.
403 Generate an object file even after errors.
405 @item -- | @var{files} @dots{}
406 Standard input, or source files to assemble.
411 The following options are available when @value{AS} is configured for
416 @cindex ARC endianness
417 @cindex endianness, ARC
418 @cindex big endian output, ARC
420 Generate ``big endian'' format output.
422 @cindex little endian output, ARC
423 @item -mlittle-endian
424 Generate ``little endian'' format output.
430 The following options are available when @value{AS} is configured for the ARM
434 @item -m[arm][1|2|3|6|7|8|9][...]
435 Specify which ARM processor variant is the target.
436 @item -m[arm]v[2|2a|3|3m|4|4t|5|5t]
437 Specify which ARM architecture variant is used by the target.
438 @item -mthumb | -mall
439 Enable or disable Thumb only instruction decoding.
440 @item -mfpa10 | -mfpa11 | -mfpe-old | -mno-fpu
441 Select which Floating Point architcture is the target.
442 @item -mapcs-32 | -mapcs-26 | -mapcs-float | -mapcs-reentrant | -moabi
443 Select which procedure calling convention is in use.
445 Select either big-endian (-EB) or little-endian (-EL) output.
446 @item -mthumb-interwork
447 Specify that the code has been generated with interworking between Thumb and
450 Specify that PIC code has been generated.
455 The following options are available when @value{AS} is configured for
458 @cindex D10V optimization
459 @cindex optimization, D10V
461 Optimize output by parallelizing instructions.
466 The following options are available when @value{AS} is configured for a D30V
469 @cindex D30V optimization
470 @cindex optimization, D30V
472 Optimize output by parallelizing instructions.
476 Warn when nops are generated.
478 @cindex D30V nops after 32-bit multiply
480 Warn when a nop after a 32-bit multiply instruction is generated.
485 The following options are available when @value{AS} is configured for the
486 Intel 80960 processor.
489 @item -ACA | -ACA_A | -ACB | -ACC | -AKA | -AKB | -AKC | -AMC
490 Specify which variant of the 960 architecture is the target.
493 Add code to collect statistics about branches taken.
496 Do not alter compare-and-branch instructions for long displacements;
503 The following options are available when @value{AS} is configured for the
504 Mitsubishi M32R series.
509 Specify which processor in the M32R family is the target. The default
510 is normally the M32R, but this option changes it to the M32RX.
512 @item --warn-explicit-parallel-conflicts or --Wp
513 Produce warning messages when questionable parallel constructs are
516 @item --no-warn-explicit-parallel-conflicts or --Wnp
517 Do not produce warning messages when questionable parallel constructs are
524 The following options are available when @value{AS} is configured for the
525 Motorola 68000 series.
530 Shorten references to undefined symbols, to one word instead of two.
532 @item -m68000 | -m68008 | -m68010 | -m68020 | -m68030 | -m68040 | -m68060
533 @itemx | -m68302 | -m68331 | -m68332 | -m68333 | -m68340 | -mcpu32 | -m5200
534 Specify what processor in the 68000 family is the target. The default
535 is normally the 68020, but this can be changed at configuration time.
537 @item -m68881 | -m68882 | -mno-68881 | -mno-68882
538 The target machine does (or does not) have a floating-point coprocessor.
539 The default is to assume a coprocessor for 68020, 68030, and cpu32. Although
540 the basic 68000 is not compatible with the 68881, a combination of the
541 two can be specified, since it's possible to do emulation of the
542 coprocessor instructions with the main processor.
544 @item -m68851 | -mno-68851
545 The target machine does (or does not) have a memory-management
546 unit coprocessor. The default is to assume an MMU for 68020 and up.
552 The following options are available when @value{AS} is configured for
553 a picoJava processor.
557 @cindex PJ endianness
558 @cindex endianness, PJ
559 @cindex big endian output, PJ
561 Generate ``big endian'' format output.
563 @cindex little endian output, PJ
565 Generate ``little endian'' format output.
571 The following options are available when @value{AS} is configured for the
572 Motorola 68HC11 or 68HC12 series.
576 @item -m68hc11 | -m68hc12
577 Specify what processor is the target. The default is
578 defined by the configuration option when building the assembler.
580 @item --force-long-branchs
581 Relative branches are turned into absolute ones. This concerns
582 conditional branches, unconditional branches and branches to a
585 @item -S | --short-branchs
586 Do not turn relative branchs into absolute ones
587 when the offset is out of range.
589 @item --strict-direct-mode
590 Do not turn the direct addressing mode into extended addressing mode
591 when the instruction does not support direct addressing mode.
593 @item --print-insn-syntax
594 Print the syntax of instruction in case of error.
596 @item --print-opcodes
597 print the list of instructions with syntax and then exit.
599 @item --generate-example
600 print an example of instruction for each possible instruction and then exit.
601 This option is only useful for testing @code{@value{AS}}.
607 The following options are available when @code{@value{AS}} is configured
608 for the SPARC architecture:
611 @item -Av6 | -Av7 | -Av8 | -Asparclet | -Asparclite
612 @itemx -Av8plus | -Av8plusa | -Av9 | -Av9a
613 Explicitly select a variant of the SPARC architecture.
615 @samp{-Av8plus} and @samp{-Av8plusa} select a 32 bit environment.
616 @samp{-Av9} and @samp{-Av9a} select a 64 bit environment.
618 @samp{-Av8plusa} and @samp{-Av9a} enable the SPARC V9 instruction set with
619 UltraSPARC extensions.
621 @item -xarch=v8plus | -xarch=v8plusa
622 For compatibility with the Solaris v9 assembler. These options are
623 equivalent to -Av8plus and -Av8plusa, respectively.
626 Warn when the assembler switches to another architecture.
631 The following options are available when @value{AS} is configured for the 'c54x
636 Enable extended addressing mode. All addresses and relocations will assume
637 extended addressing (usually 23 bits).
638 @item -mcpu=@var{CPU_VERSION}
639 Sets the CPU version being compiled for.
640 @item -merrors-to-file @var{FILENAME}
641 Redirect error output to a file, for broken systems which don't support such
642 behaviour in the shell.
647 The following options are available when @value{AS} is configured for
652 This option sets the largest size of an object that can be referenced
653 implicitly with the @code{gp} register. It is only accepted for targets that
654 use ECOFF format, such as a DECstation running Ultrix. The default value is 8.
656 @cindex MIPS endianness
657 @cindex endianness, MIPS
658 @cindex big endian output, MIPS
660 Generate ``big endian'' format output.
662 @cindex little endian output, MIPS
664 Generate ``little endian'' format output.
670 Generate code for a particular MIPS Instruction Set Architecture level.
671 @samp{-mips1} corresponds to the @sc{r2000} and @sc{r3000} processors,
672 @samp{-mips2} to the @sc{r6000} processor, and @samp{-mips3} to the @sc{r4000}
677 Generate code for the MIPS @sc{r4650} chip. This tells the assembler to accept
678 the @samp{mad} and @samp{madu} instruction, and to not schedule @samp{nop}
679 instructions around accesses to the @samp{HI} and @samp{LO} registers.
680 @samp{-no-m4650} turns off this option.
684 Generate code for the @sc{MIPS32} architecture. This tells the assembler to
685 accept ISA level 2 instructions and MIPS32 extensions including some @sc{r4000}
688 @item -mcpu=@var{CPU}
689 Generate code for a particular MIPS cpu. This has little effect on the
690 assembler, but it is passed by @code{@value{GCC}}.
693 @item --emulation=@var{name}
694 This option causes @code{@value{AS}} to emulate @code{@value{AS}} configured
695 for some other target, in all respects, including output format (choosing
696 between ELF and ECOFF only), handling of pseudo-opcodes which may generate
697 debugging information or store symbol table information, and default
698 endianness. The available configuration names are: @samp{mipsecoff},
699 @samp{mipself}, @samp{mipslecoff}, @samp{mipsbecoff}, @samp{mipslelf},
700 @samp{mipsbelf}. The first two do not alter the default endianness from that
701 of the primary target for which the assembler was configured; the others change
702 the default to little- or big-endian as indicated by the @samp{b} or @samp{l}
703 in the name. Using @samp{-EB} or @samp{-EL} will override the endianness
704 selection in any case.
706 This option is currently supported only when the primary target
707 @code{@value{AS}} is configured for is a MIPS ELF or ECOFF target.
708 Furthermore, the primary target or others specified with
709 @samp{--enable-targets=@dots{}} at configuration time must include support for
710 the other format, if both are to be available. For example, the Irix 5
711 configuration includes support for both.
713 Eventually, this option will support more configurations, with more
714 fine-grained control over the assembler's behavior, and will be supported for
718 @code{@value{AS}} ignores this option. It is accepted for compatibility with
726 Control how to deal with multiplication overflow and division by zero.
727 @samp{--trap} or @samp{--no-break} (which are synonyms) take a trap exception
728 (and only work for Instruction Set Architecture level 2 and higher);
729 @samp{--break} or @samp{--no-trap} (also synonyms, and the default) take a
735 The following options are available when @value{AS} is configured for
741 Enable or disable the JSRI to BSR transformation. By default this is enabled.
742 The command line option @samp{-nojsri2bsr} can be used to disable it.
746 Enable or disable the silicon filter behaviour. By default this is disabled.
747 The default can be overidden by the @samp{-sifilter} command line option.
750 Alter jump instructions for long displacements.
752 @item -mcpu=[210|340]
753 Select the cpu type on the target hardware. This controls which instructions
757 Assemble for a big endian target.
760 Assemble for a little endian target.
766 * Manual:: Structure of this Manual
767 * GNU Assembler:: The GNU Assembler
768 * Object Formats:: Object File Formats
769 * Command Line:: Command Line
770 * Input Files:: Input Files
771 * Object:: Output (Object) File
772 * Errors:: Error and Warning Messages
776 @section Structure of this Manual
778 @cindex manual, structure and purpose
779 This manual is intended to describe what you need to know to use
780 @sc{gnu} @code{@value{AS}}. We cover the syntax expected in source files, including
781 notation for symbols, constants, and expressions; the directives that
782 @code{@value{AS}} understands; and of course how to invoke @code{@value{AS}}.
785 We also cover special features in the @value{TARGET}
786 configuration of @code{@value{AS}}, including assembler directives.
789 This manual also describes some of the machine-dependent features of
790 various flavors of the assembler.
793 @cindex machine instructions (not covered)
794 On the other hand, this manual is @emph{not} intended as an introduction
795 to programming in assembly language---let alone programming in general!
796 In a similar vein, we make no attempt to introduce the machine
797 architecture; we do @emph{not} describe the instruction set, standard
798 mnemonics, registers or addressing modes that are standard to a
799 particular architecture.
801 You may want to consult the manufacturer's
802 machine architecture manual for this information.
806 For information on the H8/300 machine instruction set, see @cite{H8/300
807 Series Programming Manual} (Hitachi ADE--602--025). For the H8/300H,
808 see @cite{H8/300H Series Programming Manual} (Hitachi).
811 For information on the H8/500 machine instruction set, see @cite{H8/500
812 Series Programming Manual} (Hitachi M21T001).
815 For information on the Hitachi SH machine instruction set, see
816 @cite{SH-Microcomputer User's Manual} (Hitachi Micro Systems, Inc.).
819 For information on the Z8000 machine instruction set, see @cite{Z8000 CPU Technical Manual}
823 @c I think this is premature---doc@cygnus.com, 17jan1991
825 Throughout this manual, we assume that you are running @dfn{GNU},
826 the portable operating system from the @dfn{Free Software
827 Foundation, Inc.}. This restricts our attention to certain kinds of
828 computer (in particular, the kinds of computers that @sc{gnu} can run on);
829 once this assumption is granted examples and definitions need less
832 @code{@value{AS}} is part of a team of programs that turn a high-level
833 human-readable series of instructions into a low-level
834 computer-readable series of instructions. Different versions of
835 @code{@value{AS}} are used for different kinds of computer.
838 @c There used to be a section "Terminology" here, which defined
839 @c "contents", "byte", "word", and "long". Defining "word" to any
840 @c particular size is confusing when the .word directive may generate 16
841 @c bits on one machine and 32 bits on another; in general, for the user
842 @c version of this manual, none of these terms seem essential to define.
843 @c They were used very little even in the former draft of the manual;
844 @c this draft makes an effort to avoid them (except in names of
848 @section The GNU Assembler
850 @sc{gnu} @code{as} is really a family of assemblers.
852 This manual describes @code{@value{AS}}, a member of that family which is
853 configured for the @value{TARGET} architectures.
855 If you use (or have used) the @sc{gnu} assembler on one architecture, you
856 should find a fairly similar environment when you use it on another
857 architecture. Each version has much in common with the others,
858 including object file formats, most assembler directives (often called
859 @dfn{pseudo-ops}) and assembler syntax.@refill
861 @cindex purpose of @sc{gnu} assembler
862 @code{@value{AS}} is primarily intended to assemble the output of the
863 @sc{gnu} C compiler @code{@value{GCC}} for use by the linker
864 @code{@value{LD}}. Nevertheless, we've tried to make @code{@value{AS}}
865 assemble correctly everything that other assemblers for the same
866 machine would assemble.
868 Any exceptions are documented explicitly (@pxref{Machine Dependencies}).
871 @c This remark should appear in generic version of manual; assumption
872 @c here is that generic version sets M680x0.
873 This doesn't mean @code{@value{AS}} always uses the same syntax as another
874 assembler for the same architecture; for example, we know of several
875 incompatible versions of 680x0 assembly language syntax.
878 Unlike older assemblers, @code{@value{AS}} is designed to assemble a source
879 program in one pass of the source file. This has a subtle impact on the
880 @kbd{.org} directive (@pxref{Org,,@code{.org}}).
883 @section Object File Formats
885 @cindex object file format
886 The @sc{gnu} assembler can be configured to produce several alternative
887 object file formats. For the most part, this does not affect how you
888 write assembly language programs; but directives for debugging symbols
889 are typically different in different file formats. @xref{Symbol
890 Attributes,,Symbol Attributes}.
893 On the @value{TARGET}, @code{@value{AS}} is configured to produce
894 @value{OBJ-NAME} format object files.
896 @c The following should exhaust all configs that set MULTI-OBJ, ideally
898 On the @value{TARGET}, @code{@value{AS}} can be configured to produce either
899 @code{a.out} or COFF format object files.
902 On the @value{TARGET}, @code{@value{AS}} can be configured to produce either
903 @code{b.out} or COFF format object files.
906 On the @value{TARGET}, @code{@value{AS}} can be configured to produce either
907 SOM or ELF format object files.
912 @section Command Line
914 @cindex command line conventions
915 After the program name @code{@value{AS}}, the command line may contain
916 options and file names. Options may appear in any order, and may be
917 before, after, or between file names. The order of file names is
920 @cindex standard input, as input file
922 @file{--} (two hyphens) by itself names the standard input file
923 explicitly, as one of the files for @code{@value{AS}} to assemble.
925 @cindex options, command line
926 Except for @samp{--} any command line argument that begins with a
927 hyphen (@samp{-}) is an option. Each option changes the behavior of
928 @code{@value{AS}}. No option changes the way another option works. An
929 option is a @samp{-} followed by one or more letters; the case of
930 the letter is important. All options are optional.
932 Some options expect exactly one file name to follow them. The file
933 name may either immediately follow the option's letter (compatible
934 with older assemblers) or it may be the next command argument (@sc{gnu}
935 standard). These two command lines are equivalent:
938 @value{AS} -o my-object-file.o mumble.s
939 @value{AS} -omy-object-file.o mumble.s
946 @cindex source program
948 We use the phrase @dfn{source program}, abbreviated @dfn{source}, to
949 describe the program input to one run of @code{@value{AS}}. The program may
950 be in one or more files; how the source is partitioned into files
951 doesn't change the meaning of the source.
953 @c I added "con" prefix to "catenation" just to prove I can overcome my
954 @c APL training... doc@cygnus.com
955 The source program is a concatenation of the text in all the files, in the
958 Each time you run @code{@value{AS}} it assembles exactly one source
959 program. The source program is made up of one or more files.
960 (The standard input is also a file.)
962 You give @code{@value{AS}} a command line that has zero or more input file
963 names. The input files are read (from left file name to right). A
964 command line argument (in any position) that has no special meaning
965 is taken to be an input file name.
967 If you give @code{@value{AS}} no file names it attempts to read one input file
968 from the @code{@value{AS}} standard input, which is normally your terminal. You
969 may have to type @key{ctl-D} to tell @code{@value{AS}} there is no more program
972 Use @samp{--} if you need to explicitly name the standard input file
973 in your command line.
975 If the source is empty, @code{@value{AS}} produces a small, empty object
978 @subheading Filenames and Line-numbers
980 @cindex input file linenumbers
981 @cindex line numbers, in input files
982 There are two ways of locating a line in the input file (or files) and
983 either may be used in reporting error messages. One way refers to a line
984 number in a physical file; the other refers to a line number in a
985 ``logical'' file. @xref{Errors, ,Error and Warning Messages}.
987 @dfn{Physical files} are those files named in the command line given
988 to @code{@value{AS}}.
990 @dfn{Logical files} are simply names declared explicitly by assembler
991 directives; they bear no relation to physical files. Logical file names help
992 error messages reflect the original source file, when @code{@value{AS}} source
993 is itself synthesized from other files. @code{@value{AS}} understands the
994 @samp{#} directives emitted by the @code{@value{GCC}} preprocessor. See also
995 @ref{File,,@code{.file}}.
998 @section Output (Object) File
1004 Every time you run @code{@value{AS}} it produces an output file, which is
1005 your assembly language program translated into numbers. This file
1006 is the object file. Its default name is
1014 @code{b.out} when @code{@value{AS}} is configured for the Intel 80960.
1016 You can give it another name by using the @code{-o} option. Conventionally,
1017 object file names end with @file{.o}. The default name is used for historical
1018 reasons: older assemblers were capable of assembling self-contained programs
1019 directly into a runnable program. (For some formats, this isn't currently
1020 possible, but it can be done for the @code{a.out} format.)
1024 The object file is meant for input to the linker @code{@value{LD}}. It contains
1025 assembled program code, information to help @code{@value{LD}} integrate
1026 the assembled program into a runnable file, and (optionally) symbolic
1027 information for the debugger.
1029 @c link above to some info file(s) like the description of a.out.
1030 @c don't forget to describe @sc{gnu} info as well as Unix lossage.
1033 @section Error and Warning Messages
1035 @cindex error messsages
1036 @cindex warning messages
1037 @cindex messages from assembler
1038 @code{@value{AS}} may write warnings and error messages to the standard error
1039 file (usually your terminal). This should not happen when a compiler
1040 runs @code{@value{AS}} automatically. Warnings report an assumption made so
1041 that @code{@value{AS}} could keep assembling a flawed program; errors report a
1042 grave problem that stops the assembly.
1044 @cindex format of warning messages
1045 Warning messages have the format
1048 file_name:@b{NNN}:Warning Message Text
1052 @cindex line numbers, in warnings/errors
1053 (where @b{NNN} is a line number). If a logical file name has been given
1054 (@pxref{File,,@code{.file}}) it is used for the filename, otherwise the name of
1055 the current input file is used. If a logical line number was given
1057 (@pxref{Line,,@code{.line}})
1061 (@pxref{Line,,@code{.line}})
1064 (@pxref{Ln,,@code{.ln}})
1067 then it is used to calculate the number printed,
1068 otherwise the actual line in the current source file is printed. The
1069 message text is intended to be self explanatory (in the grand Unix
1072 @cindex format of error messages
1073 Error messages have the format
1075 file_name:@b{NNN}:FATAL:Error Message Text
1077 The file name and line number are derived as for warning
1078 messages. The actual message text may be rather less explanatory
1079 because many of them aren't supposed to happen.
1082 @chapter Command-Line Options
1084 @cindex options, all versions of assembler
1085 This chapter describes command-line options available in @emph{all}
1086 versions of the @sc{gnu} assembler; @pxref{Machine Dependencies}, for options specific
1088 to the @value{TARGET}.
1091 to particular machine architectures.
1094 If you are invoking @code{@value{AS}} via the @sc{gnu} C compiler (version 2),
1095 you can use the @samp{-Wa} option to pass arguments through to the assembler.
1096 The assembler arguments must be separated from each other (and the @samp{-Wa})
1097 by commas. For example:
1100 gcc -c -g -O -Wa,-alh,-L file.c
1104 This passes two options to the assembler: @samp{-alh} (emit a listing to
1105 standard output with with high-level and assembly source) and @samp{-L} (retain
1106 local symbols in the symbol table).
1108 Usually you do not need to use this @samp{-Wa} mechanism, since many compiler
1109 command-line options are automatically passed to the assembler by the compiler.
1110 (You can call the @sc{gnu} compiler driver with the @samp{-v} option to see
1111 precisely what options it passes to each compilation pass, including the
1115 * a:: -a[cdhlns] enable listings
1116 * D:: -D for compatibility
1117 * f:: -f to work faster
1118 * I:: -I for .include search path
1119 @ifclear DIFF-TBL-KLUGE
1120 * K:: -K for compatibility
1122 @ifset DIFF-TBL-KLUGE
1123 * K:: -K for difference tables
1126 * L:: -L to retain local labels
1127 * M:: -M or --mri to assemble in MRI compatibility mode
1128 * MD:: --MD for dependency tracking
1129 * o:: -o to name the object file
1130 * R:: -R to join data and text sections
1131 * statistics:: --statistics to see statistics about assembly
1132 * traditional-format:: --traditional-format for compatible output
1133 * v:: -v to announce version
1134 * W:: -W, --no-warn, --warn, --fatal-warnings to control warnings
1135 * Z:: -Z to make object file even after errors
1139 @section Enable Listings: @code{-a[cdhlns]}
1148 @cindex listings, enabling
1149 @cindex assembly listings, enabling
1151 These options enable listing output from the assembler. By itself,
1152 @samp{-a} requests high-level, assembly, and symbols listing.
1153 You can use other letters to select specific options for the list:
1154 @samp{-ah} requests a high-level language listing,
1155 @samp{-al} requests an output-program assembly listing, and
1156 @samp{-as} requests a symbol table listing.
1157 High-level listings require that a compiler debugging option like
1158 @samp{-g} be used, and that assembly listings (@samp{-al}) be requested
1161 Use the @samp{-ac} option to omit false conditionals from a listing. Any lines
1162 which are not assembled because of a false @code{.if} (or @code{.ifdef}, or any
1163 other conditional), or a true @code{.if} followed by an @code{.else}, will be
1164 omitted from the listing.
1166 Use the @samp{-ad} option to omit debugging directives from the
1169 Once you have specified one of these options, you can further control
1170 listing output and its appearance using the directives @code{.list},
1171 @code{.nolist}, @code{.psize}, @code{.eject}, @code{.title}, and
1173 The @samp{-an} option turns off all forms processing.
1174 If you do not request listing output with one of the @samp{-a} options, the
1175 listing-control directives have no effect.
1177 The letters after @samp{-a} may be combined into one option,
1178 @emph{e.g.}, @samp{-aln}.
1184 This option has no effect whatsoever, but it is accepted to make it more
1185 likely that scripts written for other assemblers also work with
1189 @section Work Faster: @code{-f}
1192 @cindex trusted compiler
1193 @cindex faster processing (@code{-f})
1194 @samp{-f} should only be used when assembling programs written by a
1195 (trusted) compiler. @samp{-f} stops the assembler from doing whitespace
1196 and comment preprocessing on
1197 the input file(s) before assembling them. @xref{Preprocessing,
1201 @emph{Warning:} if you use @samp{-f} when the files actually need to be
1202 preprocessed (if they contain comments, for example), @code{@value{AS}} does
1207 @section @code{.include} search path: @code{-I} @var{path}
1209 @kindex -I @var{path}
1210 @cindex paths for @code{.include}
1211 @cindex search path for @code{.include}
1212 @cindex @code{include} directive search path
1213 Use this option to add a @var{path} to the list of directories
1214 @code{@value{AS}} searches for files specified in @code{.include}
1215 directives (@pxref{Include,,@code{.include}}). You may use @code{-I} as
1216 many times as necessary to include a variety of paths. The current
1217 working directory is always searched first; after that, @code{@value{AS}}
1218 searches any @samp{-I} directories in the same order as they were
1219 specified (left to right) on the command line.
1222 @section Difference Tables: @code{-K}
1225 @ifclear DIFF-TBL-KLUGE
1226 On the @value{TARGET} family, this option is allowed, but has no effect. It is
1227 permitted for compatibility with the @sc{gnu} assembler on other platforms,
1228 where it can be used to warn when the assembler alters the machine code
1229 generated for @samp{.word} directives in difference tables. The @value{TARGET}
1230 family does not have the addressing limitations that sometimes lead to this
1231 alteration on other platforms.
1234 @ifset DIFF-TBL-KLUGE
1235 @cindex difference tables, warning
1236 @cindex warning for altered difference tables
1237 @code{@value{AS}} sometimes alters the code emitted for directives of the form
1238 @samp{.word @var{sym1}-@var{sym2}}; @pxref{Word,,@code{.word}}.
1239 You can use the @samp{-K} option if you want a warning issued when this
1244 @section Include Local Labels: @code{-L}
1247 @cindex local labels, retaining in output
1248 Labels beginning with @samp{L} (upper case only) are called @dfn{local
1249 labels}. @xref{Symbol Names}. Normally you do not see such labels when
1250 debugging, because they are intended for the use of programs (like
1251 compilers) that compose assembler programs, not for your notice.
1252 Normally both @code{@value{AS}} and @code{@value{LD}} discard such labels, so you do not
1253 normally debug with them.
1255 This option tells @code{@value{AS}} to retain those @samp{L@dots{}} symbols
1256 in the object file. Usually if you do this you also tell the linker
1257 @code{@value{LD}} to preserve symbols whose names begin with @samp{L}.
1259 By default, a local label is any label beginning with @samp{L}, but each
1260 target is allowed to redefine the local label prefix.
1262 On the HPPA local labels begin with @samp{L$}.
1266 @section Assemble in MRI Compatibility Mode: @code{-M}
1269 @cindex MRI compatibility mode
1270 The @code{-M} or @code{--mri} option selects MRI compatibility mode. This
1271 changes the syntax and pseudo-op handling of @code{@value{AS}} to make it
1272 compatible with the @code{ASM68K} or the @code{ASM960} (depending upon the
1273 configured target) assembler from Microtec Research. The exact nature of the
1274 MRI syntax will not be documented here; see the MRI manuals for more
1275 information. Note in particular that the handling of macros and macro
1276 arguments is somewhat different. The purpose of this option is to permit
1277 assembling existing MRI assembler code using @code{@value{AS}}.
1279 The MRI compatibility is not complete. Certain operations of the MRI assembler
1280 depend upon its object file format, and can not be supported using other object
1281 file formats. Supporting these would require enhancing each object file format
1282 individually. These are:
1285 @item global symbols in common section
1287 The m68k MRI assembler supports common sections which are merged by the linker.
1288 Other object file formats do not support this. @code{@value{AS}} handles
1289 common sections by treating them as a single common symbol. It permits local
1290 symbols to be defined within a common section, but it can not support global
1291 symbols, since it has no way to describe them.
1293 @item complex relocations
1295 The MRI assemblers support relocations against a negated section address, and
1296 relocations which combine the start addresses of two or more sections. These
1297 are not support by other object file formats.
1299 @item @code{END} pseudo-op specifying start address
1301 The MRI @code{END} pseudo-op permits the specification of a start address.
1302 This is not supported by other object file formats. The start address may
1303 instead be specified using the @code{-e} option to the linker, or in a linker
1306 @item @code{IDNT}, @code{.ident} and @code{NAME} pseudo-ops
1308 The MRI @code{IDNT}, @code{.ident} and @code{NAME} pseudo-ops assign a module
1309 name to the output file. This is not supported by other object file formats.
1311 @item @code{ORG} pseudo-op
1313 The m68k MRI @code{ORG} pseudo-op begins an absolute section at a given
1314 address. This differs from the usual @code{@value{AS}} @code{.org} pseudo-op,
1315 which changes the location within the current section. Absolute sections are
1316 not supported by other object file formats. The address of a section may be
1317 assigned within a linker script.
1320 There are some other features of the MRI assembler which are not supported by
1321 @code{@value{AS}}, typically either because they are difficult or because they
1322 seem of little consequence. Some of these may be supported in future releases.
1326 @item EBCDIC strings
1328 EBCDIC strings are not supported.
1330 @item packed binary coded decimal
1332 Packed binary coded decimal is not supported. This means that the @code{DC.P}
1333 and @code{DCB.P} pseudo-ops are not supported.
1335 @item @code{FEQU} pseudo-op
1337 The m68k @code{FEQU} pseudo-op is not supported.
1339 @item @code{NOOBJ} pseudo-op
1341 The m68k @code{NOOBJ} pseudo-op is not supported.
1343 @item @code{OPT} branch control options
1345 The m68k @code{OPT} branch control options---@code{B}, @code{BRS}, @code{BRB},
1346 @code{BRL}, and @code{BRW}---are ignored. @code{@value{AS}} automatically
1347 relaxes all branches, whether forward or backward, to an appropriate size, so
1348 these options serve no purpose.
1350 @item @code{OPT} list control options
1352 The following m68k @code{OPT} list control options are ignored: @code{C},
1353 @code{CEX}, @code{CL}, @code{CRE}, @code{E}, @code{G}, @code{I}, @code{M},
1354 @code{MEX}, @code{MC}, @code{MD}, @code{X}.
1356 @item other @code{OPT} options
1358 The following m68k @code{OPT} options are ignored: @code{NEST}, @code{O},
1359 @code{OLD}, @code{OP}, @code{P}, @code{PCO}, @code{PCR}, @code{PCS}, @code{R}.
1361 @item @code{OPT} @code{D} option is default
1363 The m68k @code{OPT} @code{D} option is the default, unlike the MRI assembler.
1364 @code{OPT NOD} may be used to turn it off.
1366 @item @code{XREF} pseudo-op.
1368 The m68k @code{XREF} pseudo-op is ignored.
1370 @item @code{.debug} pseudo-op
1372 The i960 @code{.debug} pseudo-op is not supported.
1374 @item @code{.extended} pseudo-op
1376 The i960 @code{.extended} pseudo-op is not supported.
1378 @item @code{.list} pseudo-op.
1380 The various options of the i960 @code{.list} pseudo-op are not supported.
1382 @item @code{.optimize} pseudo-op
1384 The i960 @code{.optimize} pseudo-op is not supported.
1386 @item @code{.output} pseudo-op
1388 The i960 @code{.output} pseudo-op is not supported.
1390 @item @code{.setreal} pseudo-op
1392 The i960 @code{.setreal} pseudo-op is not supported.
1397 @section Dependency tracking: @code{--MD}
1400 @cindex dependency tracking
1403 @code{@value{AS}} can generate a dependency file for the file it creates. This
1404 file consists of a single rule suitable for @code{make} describing the
1405 dependencies of the main source file.
1407 The rule is written to the file named in its argument.
1409 This feature is used in the automatic updating of makefiles.
1412 @section Name the Object File: @code{-o}
1415 @cindex naming object file
1416 @cindex object file name
1417 There is always one object file output when you run @code{@value{AS}}. By
1418 default it has the name
1421 @file{a.out} (or @file{b.out}, for Intel 960 targets only).
1435 You use this option (which takes exactly one filename) to give the
1436 object file a different name.
1438 Whatever the object file is called, @code{@value{AS}} overwrites any
1439 existing file of the same name.
1442 @section Join Data and Text Sections: @code{-R}
1445 @cindex data and text sections, joining
1446 @cindex text and data sections, joining
1447 @cindex joining text and data sections
1448 @cindex merging text and data sections
1449 @code{-R} tells @code{@value{AS}} to write the object file as if all
1450 data-section data lives in the text section. This is only done at
1451 the very last moment: your binary data are the same, but data
1452 section parts are relocated differently. The data section part of
1453 your object file is zero bytes long because all its bytes are
1454 appended to the text section. (@xref{Sections,,Sections and Relocation}.)
1456 When you specify @code{-R} it would be possible to generate shorter
1457 address displacements (because we do not have to cross between text and
1458 data section). We refrain from doing this simply for compatibility with
1459 older versions of @code{@value{AS}}. In future, @code{-R} may work this way.
1462 When @code{@value{AS}} is configured for COFF output,
1463 this option is only useful if you use sections named @samp{.text} and
1468 @code{-R} is not supported for any of the HPPA targets. Using
1469 @code{-R} generates a warning from @code{@value{AS}}.
1473 @section Display Assembly Statistics: @code{--statistics}
1475 @kindex --statistics
1476 @cindex statistics, about assembly
1477 @cindex time, total for assembly
1478 @cindex space used, maximum for assembly
1479 Use @samp{--statistics} to display two statistics about the resources used by
1480 @code{@value{AS}}: the maximum amount of space allocated during the assembly
1481 (in bytes), and the total execution time taken for the assembly (in @sc{cpu}
1484 @node traditional-format
1485 @section Compatible output: @code{--traditional-format}
1487 @kindex --traditional-format
1488 For some targets, the output of @code{@value{AS}} is different in some ways
1489 from the output of some existing assembler. This switch requests
1490 @code{@value{AS}} to use the traditional format instead.
1492 For example, it disables the exception frame optimizations which
1493 @code{@value{AS}} normally does by default on @code{@value{GCC}} output.
1496 @section Announce Version: @code{-v}
1500 @cindex assembler version
1501 @cindex version of assembler
1502 You can find out what version of as is running by including the
1503 option @samp{-v} (which you can also spell as @samp{-version}) on the
1507 @section Control Warnings: @code{-W}, @code{--warn}, @code{--no-warn}, @code{--fatal-warnings}
1509 @code{@value{AS}} should never give a warning or error message when
1510 assembling compiler output. But programs written by people often
1511 cause @code{@value{AS}} to give a warning that a particular assumption was
1512 made. All such warnings are directed to the standard error file.
1515 @kindex @samp{--no-warn}
1516 @cindex suppressing warnings
1517 @cindex warnings, suppressing
1518 If you use the @code{-W} and @code{--no-warn} options, no warnings are issued.
1519 This only affects the warning messages: it does not change any particular of
1520 how @code{@value{AS}} assembles your file. Errors, which stop the assembly,
1523 @kindex @samp{--fatal-warnings}
1524 @cindex errors, caused by warnings
1525 @cindex warnings, causing error
1526 If you use the @code{--fatal-warnings} option, @code{@value{AS}} considers
1527 files that generate warnings to be in error.
1529 @kindex @samp{--warn}
1530 @cindex warnings, switching on
1531 You can switch these options off again by specifying @code{--warn}, which
1532 causes warnings to be output as usual.
1535 @section Generate Object File in Spite of Errors: @code{-Z}
1536 @cindex object file, after errors
1537 @cindex errors, continuing after
1538 After an error message, @code{@value{AS}} normally produces no output. If for
1539 some reason you are interested in object file output even after
1540 @code{@value{AS}} gives an error message on your program, use the @samp{-Z}
1541 option. If there are any errors, @code{@value{AS}} continues anyways, and
1542 writes an object file after a final warning message of the form @samp{@var{n}
1543 errors, @var{m} warnings, generating bad object file.}
1548 @cindex machine-independent syntax
1549 @cindex syntax, machine-independent
1550 This chapter describes the machine-independent syntax allowed in a
1551 source file. @code{@value{AS}} syntax is similar to what many other
1552 assemblers use; it is inspired by the BSD 4.2
1557 assembler, except that @code{@value{AS}} does not assemble Vax bit-fields.
1561 * Preprocessing:: Preprocessing
1562 * Whitespace:: Whitespace
1563 * Comments:: Comments
1564 * Symbol Intro:: Symbols
1565 * Statements:: Statements
1566 * Constants:: Constants
1570 @section Preprocessing
1572 @cindex preprocessing
1573 The @code{@value{AS}} internal preprocessor:
1575 @cindex whitespace, removed by preprocessor
1577 adjusts and removes extra whitespace. It leaves one space or tab before
1578 the keywords on a line, and turns any other whitespace on the line into
1581 @cindex comments, removed by preprocessor
1583 removes all comments, replacing them with a single space, or an
1584 appropriate number of newlines.
1586 @cindex constants, converted by preprocessor
1588 converts character constants into the appropriate numeric values.
1591 It does not do macro processing, include file handling, or
1592 anything else you may get from your C compiler's preprocessor. You can
1593 do include file processing with the @code{.include} directive
1594 (@pxref{Include,,@code{.include}}). You can use the @sc{gnu} C compiler driver
1595 to get other ``CPP'' style preprocessing, by giving the input file a
1596 @samp{.S} suffix. @xref{Overall Options,, Options Controlling the Kind of
1597 Output, gcc.info, Using GNU CC}.
1599 Excess whitespace, comments, and character constants
1600 cannot be used in the portions of the input text that are not
1603 @cindex turning preprocessing on and off
1604 @cindex preprocessing, turning on and off
1607 If the first line of an input file is @code{#NO_APP} or if you use the
1608 @samp{-f} option, whitespace and comments are not removed from the input file.
1609 Within an input file, you can ask for whitespace and comment removal in
1610 specific portions of the by putting a line that says @code{#APP} before the
1611 text that may contain whitespace or comments, and putting a line that says
1612 @code{#NO_APP} after this text. This feature is mainly intend to support
1613 @code{asm} statements in compilers whose output is otherwise free of comments
1620 @dfn{Whitespace} is one or more blanks or tabs, in any order.
1621 Whitespace is used to separate symbols, and to make programs neater for
1622 people to read. Unless within character constants
1623 (@pxref{Characters,,Character Constants}), any whitespace means the same
1624 as exactly one space.
1630 There are two ways of rendering comments to @code{@value{AS}}. In both
1631 cases the comment is equivalent to one space.
1633 Anything from @samp{/*} through the next @samp{*/} is a comment.
1634 This means you may not nest these comments.
1638 The only way to include a newline ('\n') in a comment
1639 is to use this sort of comment.
1642 /* This sort of comment does not nest. */
1645 @cindex line comment character
1646 Anything from the @dfn{line comment} character to the next newline
1647 is considered a comment and is ignored. The line comment character is
1649 @samp{;} for the AMD 29K family;
1652 @samp{;} on the ARC;
1655 @samp{@@} on the ARM;
1658 @samp{;} for the H8/300 family;
1661 @samp{!} for the H8/500 family;
1664 @samp{;} for the HPPA;
1667 @samp{#} on the i960;
1670 @samp{;} for picoJava;
1673 @samp{!} for the Hitachi SH;
1676 @samp{!} on the SPARC;
1679 @samp{#} on the m32r;
1682 @samp{|} on the 680x0;
1685 @samp{#} on the 68HC11 and 68HC12;
1688 @samp{#} on the Vax;
1691 @samp{!} for the Z8000;
1694 @samp{#} on the V850;
1696 see @ref{Machine Dependencies}. @refill
1697 @c FIXME What about i386, m88k, i860?
1700 On some machines there are two different line comment characters. One
1701 character only begins a comment if it is the first non-whitespace character on
1702 a line, while the other always begins a comment.
1706 The V850 assembler also supports a double dash as starting a comment that
1707 extends to the end of the line.
1713 @cindex lines starting with @code{#}
1714 @cindex logical line numbers
1715 To be compatible with past assemblers, lines that begin with @samp{#} have a
1716 special interpretation. Following the @samp{#} should be an absolute
1717 expression (@pxref{Expressions}): the logical line number of the @emph{next}
1718 line. Then a string (@pxref{Strings,, Strings}) is allowed: if present it is a
1719 new logical file name. The rest of the line, if any, should be whitespace.
1721 If the first non-whitespace characters on the line are not numeric,
1722 the line is ignored. (Just like a comment.)
1725 # This is an ordinary comment.
1726 # 42-6 "new_file_name" # New logical file name
1727 # This is logical line # 36.
1729 This feature is deprecated, and may disappear from future versions
1730 of @code{@value{AS}}.
1735 @cindex characters used in symbols
1736 @ifclear SPECIAL-SYMS
1737 A @dfn{symbol} is one or more characters chosen from the set of all
1738 letters (both upper and lower case), digits and the three characters
1744 A @dfn{symbol} is one or more characters chosen from the set of all
1745 letters (both upper and lower case), digits and the three characters
1746 @samp{._$}. (Save that, on the H8/300 only, you may not use @samp{$} in
1752 On most machines, you can also use @code{$} in symbol names; exceptions
1753 are noted in @ref{Machine Dependencies}.
1755 No symbol may begin with a digit. Case is significant.
1756 There is no length limit: all characters are significant. Symbols are
1757 delimited by characters not in that set, or by the beginning of a file
1758 (since the source program must end with a newline, the end of a file is
1759 not a possible symbol delimiter). @xref{Symbols}.
1760 @cindex length of symbols
1765 @cindex statements, structure of
1766 @cindex line separator character
1767 @cindex statement separator character
1769 @ifclear abnormal-separator
1770 A @dfn{statement} ends at a newline character (@samp{\n}) or at a
1771 semicolon (@samp{;}). The newline or semicolon is considered part of
1772 the preceding statement. Newlines and semicolons within character
1773 constants are an exception: they do not end statements.
1775 @ifset abnormal-separator
1777 A @dfn{statement} ends at a newline character (@samp{\n}) or an ``at''
1778 sign (@samp{@@}). The newline or at sign is considered part of the
1779 preceding statement. Newlines and at signs within character constants
1780 are an exception: they do not end statements.
1783 A @dfn{statement} ends at a newline character (@samp{\n}) or an exclamation
1784 point (@samp{!}). The newline or exclamation point is considered part of the
1785 preceding statement. Newlines and exclamation points within character
1786 constants are an exception: they do not end statements.
1789 A @dfn{statement} ends at a newline character (@samp{\n}); or (for the
1790 H8/300) a dollar sign (@samp{$}); or (for the
1793 (@samp{;}). The newline or separator character is considered part of
1794 the preceding statement. Newlines and separators within character
1795 constants are an exception: they do not end statements.
1800 A @dfn{statement} ends at a newline character (@samp{\n}) or line
1801 separator character. (The line separator is usually @samp{;}, unless
1802 this conflicts with the comment character; @pxref{Machine Dependencies}.) The
1803 newline or separator character is considered part of the preceding
1804 statement. Newlines and separators within character constants are an
1805 exception: they do not end statements.
1808 @cindex newline, required at file end
1809 @cindex EOF, newline must precede
1810 It is an error to end any statement with end-of-file: the last
1811 character of any input file should be a newline.@refill
1813 An empty statement is allowed, and may include whitespace. It is ignored.
1815 @cindex instructions and directives
1816 @cindex directives and instructions
1817 @c "key symbol" is not used elsewhere in the document; seems pedantic to
1818 @c @defn{} it in that case, as was done previously... doc@cygnus.com,
1820 A statement begins with zero or more labels, optionally followed by a
1821 key symbol which determines what kind of statement it is. The key
1822 symbol determines the syntax of the rest of the statement. If the
1823 symbol begins with a dot @samp{.} then the statement is an assembler
1824 directive: typically valid for any computer. If the symbol begins with
1825 a letter the statement is an assembly language @dfn{instruction}: it
1826 assembles into a machine language instruction.
1828 Different versions of @code{@value{AS}} for different computers
1829 recognize different instructions. In fact, the same symbol may
1830 represent a different instruction in a different computer's assembly
1834 @cindex @code{:} (label)
1835 @cindex label (@code{:})
1836 A label is a symbol immediately followed by a colon (@code{:}).
1837 Whitespace before a label or after a colon is permitted, but you may not
1838 have whitespace between a label's symbol and its colon. @xref{Labels}.
1841 For HPPA targets, labels need not be immediately followed by a colon, but
1842 the definition of a label must begin in column zero. This also implies that
1843 only one label may be defined on each line.
1847 label: .directive followed by something
1848 another_label: # This is an empty statement.
1849 instruction operand_1, operand_2, @dots{}
1856 A constant is a number, written so that its value is known by
1857 inspection, without knowing any context. Like this:
1860 .byte 74, 0112, 092, 0x4A, 0X4a, 'J, '\J # All the same value.
1861 .ascii "Ring the bell\7" # A string constant.
1862 .octa 0x123456789abcdef0123456789ABCDEF0 # A bignum.
1863 .float 0f-314159265358979323846264338327\
1864 95028841971.693993751E-40 # - pi, a flonum.
1869 * Characters:: Character Constants
1870 * Numbers:: Number Constants
1874 @subsection Character Constants
1876 @cindex character constants
1877 @cindex constants, character
1878 There are two kinds of character constants. A @dfn{character} stands
1879 for one character in one byte and its value may be used in
1880 numeric expressions. String constants (properly called string
1881 @emph{literals}) are potentially many bytes and their values may not be
1882 used in arithmetic expressions.
1886 * Chars:: Characters
1890 @subsubsection Strings
1892 @cindex string constants
1893 @cindex constants, string
1894 A @dfn{string} is written between double-quotes. It may contain
1895 double-quotes or null characters. The way to get special characters
1896 into a string is to @dfn{escape} these characters: precede them with
1897 a backslash @samp{\} character. For example @samp{\\} represents
1898 one backslash: the first @code{\} is an escape which tells
1899 @code{@value{AS}} to interpret the second character literally as a backslash
1900 (which prevents @code{@value{AS}} from recognizing the second @code{\} as an
1901 escape character). The complete list of escapes follows.
1903 @cindex escape codes, character
1904 @cindex character escape codes
1907 @c Mnemonic for ACKnowledge; for ASCII this is octal code 007.
1909 @cindex @code{\b} (backspace character)
1910 @cindex backspace (@code{\b})
1912 Mnemonic for backspace; for ASCII this is octal code 010.
1915 @c Mnemonic for EOText; for ASCII this is octal code 004.
1917 @cindex @code{\f} (formfeed character)
1918 @cindex formfeed (@code{\f})
1920 Mnemonic for FormFeed; for ASCII this is octal code 014.
1922 @cindex @code{\n} (newline character)
1923 @cindex newline (@code{\n})
1925 Mnemonic for newline; for ASCII this is octal code 012.
1928 @c Mnemonic for prefix; for ASCII this is octal code 033, usually known as @code{escape}.
1930 @cindex @code{\r} (carriage return character)
1931 @cindex carriage return (@code{\r})
1933 Mnemonic for carriage-Return; for ASCII this is octal code 015.
1936 @c Mnemonic for space; for ASCII this is octal code 040. Included for compliance with
1937 @c other assemblers.
1939 @cindex @code{\t} (tab)
1940 @cindex tab (@code{\t})
1942 Mnemonic for horizontal Tab; for ASCII this is octal code 011.
1945 @c Mnemonic for Vertical tab; for ASCII this is octal code 013.
1946 @c @item \x @var{digit} @var{digit} @var{digit}
1947 @c A hexadecimal character code. The numeric code is 3 hexadecimal digits.
1949 @cindex @code{\@var{ddd}} (octal character code)
1950 @cindex octal character code (@code{\@var{ddd}})
1951 @item \ @var{digit} @var{digit} @var{digit}
1952 An octal character code. The numeric code is 3 octal digits.
1953 For compatibility with other Unix systems, 8 and 9 are accepted as digits:
1954 for example, @code{\008} has the value 010, and @code{\009} the value 011.
1956 @cindex @code{\@var{xd...}} (hex character code)
1957 @cindex hex character code (@code{\@var{xd...}})
1958 @item \@code{x} @var{hex-digits...}
1959 A hex character code. All trailing hex digits are combined. Either upper or
1960 lower case @code{x} works.
1962 @cindex @code{\\} (@samp{\} character)
1963 @cindex backslash (@code{\\})
1965 Represents one @samp{\} character.
1968 @c Represents one @samp{'} (accent acute) character.
1969 @c This is needed in single character literals
1970 @c (@xref{Characters,,Character Constants}.) to represent
1973 @cindex @code{\"} (doublequote character)
1974 @cindex doublequote (@code{\"})
1976 Represents one @samp{"} character. Needed in strings to represent
1977 this character, because an unescaped @samp{"} would end the string.
1979 @item \ @var{anything-else}
1980 Any other character when escaped by @kbd{\} gives a warning, but
1981 assembles as if the @samp{\} was not present. The idea is that if
1982 you used an escape sequence you clearly didn't want the literal
1983 interpretation of the following character. However @code{@value{AS}} has no
1984 other interpretation, so @code{@value{AS}} knows it is giving you the wrong
1985 code and warns you of the fact.
1988 Which characters are escapable, and what those escapes represent,
1989 varies widely among assemblers. The current set is what we think
1990 the BSD 4.2 assembler recognizes, and is a subset of what most C
1991 compilers recognize. If you are in doubt, do not use an escape
1995 @subsubsection Characters
1997 @cindex single character constant
1998 @cindex character, single
1999 @cindex constant, single character
2000 A single character may be written as a single quote immediately
2001 followed by that character. The same escapes apply to characters as
2002 to strings. So if you want to write the character backslash, you
2003 must write @kbd{'\\} where the first @code{\} escapes the second
2004 @code{\}. As you can see, the quote is an acute accent, not a
2005 grave accent. A newline
2007 @ifclear abnormal-separator
2008 (or semicolon @samp{;})
2010 @ifset abnormal-separator
2012 (or at sign @samp{@@})
2015 (or dollar sign @samp{$}, for the H8/300; or semicolon @samp{;} for the
2021 immediately following an acute accent is taken as a literal character
2022 and does not count as the end of a statement. The value of a character
2023 constant in a numeric expression is the machine's byte-wide code for
2024 that character. @code{@value{AS}} assumes your character code is ASCII:
2025 @kbd{'A} means 65, @kbd{'B} means 66, and so on. @refill
2028 @subsection Number Constants
2030 @cindex constants, number
2031 @cindex number constants
2032 @code{@value{AS}} distinguishes three kinds of numbers according to how they
2033 are stored in the target machine. @emph{Integers} are numbers that
2034 would fit into an @code{int} in the C language. @emph{Bignums} are
2035 integers, but they are stored in more than 32 bits. @emph{Flonums}
2036 are floating point numbers, described below.
2039 * Integers:: Integers
2044 * Bit Fields:: Bit Fields
2050 @subsubsection Integers
2052 @cindex constants, integer
2054 @cindex binary integers
2055 @cindex integers, binary
2056 A binary integer is @samp{0b} or @samp{0B} followed by zero or more of
2057 the binary digits @samp{01}.
2059 @cindex octal integers
2060 @cindex integers, octal
2061 An octal integer is @samp{0} followed by zero or more of the octal
2062 digits (@samp{01234567}).
2064 @cindex decimal integers
2065 @cindex integers, decimal
2066 A decimal integer starts with a non-zero digit followed by zero or
2067 more digits (@samp{0123456789}).
2069 @cindex hexadecimal integers
2070 @cindex integers, hexadecimal
2071 A hexadecimal integer is @samp{0x} or @samp{0X} followed by one or
2072 more hexadecimal digits chosen from @samp{0123456789abcdefABCDEF}.
2074 Integers have the usual values. To denote a negative integer, use
2075 the prefix operator @samp{-} discussed under expressions
2076 (@pxref{Prefix Ops,,Prefix Operators}).
2079 @subsubsection Bignums
2082 @cindex constants, bignum
2083 A @dfn{bignum} has the same syntax and semantics as an integer
2084 except that the number (or its negative) takes more than 32 bits to
2085 represent in binary. The distinction is made because in some places
2086 integers are permitted while bignums are not.
2089 @subsubsection Flonums
2091 @cindex floating point numbers
2092 @cindex constants, floating point
2094 @cindex precision, floating point
2095 A @dfn{flonum} represents a floating point number. The translation is
2096 indirect: a decimal floating point number from the text is converted by
2097 @code{@value{AS}} to a generic binary floating point number of more than
2098 sufficient precision. This generic floating point number is converted
2099 to a particular computer's floating point format (or formats) by a
2100 portion of @code{@value{AS}} specialized to that computer.
2102 A flonum is written by writing (in order)
2107 (@samp{0} is optional on the HPPA.)
2111 A letter, to tell @code{@value{AS}} the rest of the number is a flonum.
2113 @kbd{e} is recommended. Case is not important.
2115 @c FIXME: verify if flonum syntax really this vague for most cases
2116 (Any otherwise illegal letter works here, but that might be changed. Vax BSD
2117 4.2 assembler seems to allow any of @samp{defghDEFGH}.)
2120 On the H8/300, H8/500,
2122 and AMD 29K architectures, the letter must be
2123 one of the letters @samp{DFPRSX} (in upper or lower case).
2125 On the ARC, the letter must be one of the letters @samp{DFRS}
2126 (in upper or lower case).
2128 On the Intel 960 architecture, the letter must be
2129 one of the letters @samp{DFT} (in upper or lower case).
2131 On the HPPA architecture, the letter must be @samp{E} (upper case only).
2135 One of the letters @samp{DFPRSX} (in upper or lower case).
2138 One of the letters @samp{DFRS} (in upper or lower case).
2141 One of the letters @samp{DFPRSX} (in upper or lower case).
2144 The letter @samp{E} (upper case only).
2147 One of the letters @samp{DFT} (in upper or lower case).
2152 An optional sign: either @samp{+} or @samp{-}.
2155 An optional @dfn{integer part}: zero or more decimal digits.
2158 An optional @dfn{fractional part}: @samp{.} followed by zero
2159 or more decimal digits.
2162 An optional exponent, consisting of:
2166 An @samp{E} or @samp{e}.
2167 @c I can't find a config where "EXP_CHARS" is other than 'eE', but in
2168 @c principle this can perfectly well be different on different targets.
2170 Optional sign: either @samp{+} or @samp{-}.
2172 One or more decimal digits.
2177 At least one of the integer part or the fractional part must be
2178 present. The floating point number has the usual base-10 value.
2180 @code{@value{AS}} does all processing using integers. Flonums are computed
2181 independently of any floating point hardware in the computer running
2186 @c Bit fields are written as a general facility but are also controlled
2187 @c by a conditional-compilation flag---which is as of now (21mar91)
2188 @c turned on only by the i960 config of GAS.
2190 @subsubsection Bit Fields
2193 @cindex constants, bit field
2194 You can also define numeric constants as @dfn{bit fields}.
2195 specify two numbers separated by a colon---
2197 @var{mask}:@var{value}
2200 @code{@value{AS}} applies a bitwise @sc{and} between @var{mask} and
2203 The resulting number is then packed
2205 @c this conditional paren in case bit fields turned on elsewhere than 960
2206 (in host-dependent byte order)
2208 into a field whose width depends on which assembler directive has the
2209 bit-field as its argument. Overflow (a result from the bitwise and
2210 requiring more binary digits to represent) is not an error; instead,
2211 more constants are generated, of the specified width, beginning with the
2212 least significant digits.@refill
2214 The directives @code{.byte}, @code{.hword}, @code{.int}, @code{.long},
2215 @code{.short}, and @code{.word} accept bit-field arguments.
2220 @chapter Sections and Relocation
2225 * Secs Background:: Background
2226 * Ld Sections:: Linker Sections
2227 * As Sections:: Assembler Internal Sections
2228 * Sub-Sections:: Sub-Sections
2232 @node Secs Background
2235 Roughly, a section is a range of addresses, with no gaps; all data
2236 ``in'' those addresses is treated the same for some particular purpose.
2237 For example there may be a ``read only'' section.
2239 @cindex linker, and assembler
2240 @cindex assembler, and linker
2241 The linker @code{@value{LD}} reads many object files (partial programs) and
2242 combines their contents to form a runnable program. When @code{@value{AS}}
2243 emits an object file, the partial program is assumed to start at address 0.
2244 @code{@value{LD}} assigns the final addresses for the partial program, so that
2245 different partial programs do not overlap. This is actually an
2246 oversimplification, but it suffices to explain how @code{@value{AS}} uses
2249 @code{@value{LD}} moves blocks of bytes of your program to their run-time
2250 addresses. These blocks slide to their run-time addresses as rigid
2251 units; their length does not change and neither does the order of bytes
2252 within them. Such a rigid unit is called a @emph{section}. Assigning
2253 run-time addresses to sections is called @dfn{relocation}. It includes
2254 the task of adjusting mentions of object-file addresses so they refer to
2255 the proper run-time addresses.
2257 For the H8/300 and H8/500,
2258 and for the Hitachi SH,
2259 @code{@value{AS}} pads sections if needed to
2260 ensure they end on a word (sixteen bit) boundary.
2263 @cindex standard assembler sections
2264 An object file written by @code{@value{AS}} has at least three sections, any
2265 of which may be empty. These are named @dfn{text}, @dfn{data} and
2270 When it generates COFF output,
2272 @code{@value{AS}} can also generate whatever other named sections you specify
2273 using the @samp{.section} directive (@pxref{Section,,@code{.section}}).
2274 If you do not use any directives that place output in the @samp{.text}
2275 or @samp{.data} sections, these sections still exist, but are empty.
2280 When @code{@value{AS}} generates SOM or ELF output for the HPPA,
2282 @code{@value{AS}} can also generate whatever other named sections you
2283 specify using the @samp{.space} and @samp{.subspace} directives. See
2284 @cite{HP9000 Series 800 Assembly Language Reference Manual}
2285 (HP 92432-90001) for details on the @samp{.space} and @samp{.subspace}
2286 assembler directives.
2289 Additionally, @code{@value{AS}} uses different names for the standard
2290 text, data, and bss sections when generating SOM output. Program text
2291 is placed into the @samp{$CODE$} section, data into @samp{$DATA$}, and
2292 BSS into @samp{$BSS$}.
2296 Within the object file, the text section starts at address @code{0}, the
2297 data section follows, and the bss section follows the data section.
2300 When generating either SOM or ELF output files on the HPPA, the text
2301 section starts at address @code{0}, the data section at address
2302 @code{0x4000000}, and the bss section follows the data section.
2305 To let @code{@value{LD}} know which data changes when the sections are
2306 relocated, and how to change that data, @code{@value{AS}} also writes to the
2307 object file details of the relocation needed. To perform relocation
2308 @code{@value{LD}} must know, each time an address in the object
2312 Where in the object file is the beginning of this reference to
2315 How long (in bytes) is this reference?
2317 Which section does the address refer to? What is the numeric value of
2319 (@var{address}) @minus{} (@var{start-address of section})?
2322 Is the reference to an address ``Program-Counter relative''?
2325 @cindex addresses, format of
2326 @cindex section-relative addressing
2327 In fact, every address @code{@value{AS}} ever uses is expressed as
2329 (@var{section}) + (@var{offset into section})
2332 Further, most expressions @code{@value{AS}} computes have this section-relative
2335 (For some object formats, such as SOM for the HPPA, some expressions are
2336 symbol-relative instead.)
2339 In this manual we use the notation @{@var{secname} @var{N}@} to mean ``offset
2340 @var{N} into section @var{secname}.''
2342 Apart from text, data and bss sections you need to know about the
2343 @dfn{absolute} section. When @code{@value{LD}} mixes partial programs,
2344 addresses in the absolute section remain unchanged. For example, address
2345 @code{@{absolute 0@}} is ``relocated'' to run-time address 0 by
2346 @code{@value{LD}}. Although the linker never arranges two partial programs'
2347 data sections with overlapping addresses after linking, @emph{by definition}
2348 their absolute sections must overlap. Address @code{@{absolute@ 239@}} in one
2349 part of a program is always the same address when the program is running as
2350 address @code{@{absolute@ 239@}} in any other part of the program.
2352 The idea of sections is extended to the @dfn{undefined} section. Any
2353 address whose section is unknown at assembly time is by definition
2354 rendered @{undefined @var{U}@}---where @var{U} is filled in later.
2355 Since numbers are always defined, the only way to generate an undefined
2356 address is to mention an undefined symbol. A reference to a named
2357 common block would be such a symbol: its value is unknown at assembly
2358 time so it has section @emph{undefined}.
2360 By analogy the word @emph{section} is used to describe groups of sections in
2361 the linked program. @code{@value{LD}} puts all partial programs' text
2362 sections in contiguous addresses in the linked program. It is
2363 customary to refer to the @emph{text section} of a program, meaning all
2364 the addresses of all partial programs' text sections. Likewise for
2365 data and bss sections.
2367 Some sections are manipulated by @code{@value{LD}}; others are invented for
2368 use of @code{@value{AS}} and have no meaning except during assembly.
2371 @section Linker Sections
2372 @code{@value{LD}} deals with just four kinds of sections, summarized below.
2377 @cindex named sections
2378 @cindex sections, named
2379 @item named sections
2382 @cindex text section
2383 @cindex data section
2387 These sections hold your program. @code{@value{AS}} and @code{@value{LD}} treat them as
2388 separate but equal sections. Anything you can say of one section is
2391 When the program is running, however, it is
2392 customary for the text section to be unalterable. The
2393 text section is often shared among processes: it contains
2394 instructions, constants and the like. The data section of a running
2395 program is usually alterable: for example, C variables would be stored
2396 in the data section.
2401 This section contains zeroed bytes when your program begins running. It
2402 is used to hold unitialized variables or common storage. The length of
2403 each partial program's bss section is important, but because it starts
2404 out containing zeroed bytes there is no need to store explicit zero
2405 bytes in the object file. The bss section was invented to eliminate
2406 those explicit zeros from object files.
2408 @cindex absolute section
2409 @item absolute section
2410 Address 0 of this section is always ``relocated'' to runtime address 0.
2411 This is useful if you want to refer to an address that @code{@value{LD}} must
2412 not change when relocating. In this sense we speak of absolute
2413 addresses being ``unrelocatable'': they do not change during relocation.
2415 @cindex undefined section
2416 @item undefined section
2417 This ``section'' is a catch-all for address references to objects not in
2418 the preceding sections.
2419 @c FIXME: ref to some other doc on obj-file formats could go here.
2422 @cindex relocation example
2423 An idealized example of three relocatable sections follows.
2425 The example uses the traditional section names @samp{.text} and @samp{.data}.
2427 Memory addresses are on the horizontal axis.
2431 @c END TEXI2ROFF-KILL
2434 partial program # 1: |ttttt|dddd|00|
2441 partial program # 2: |TTT|DDD|000|
2444 +--+---+-----+--+----+---+-----+~~
2445 linked program: | |TTT|ttttt| |dddd|DDD|00000|
2446 +--+---+-----+--+----+---+-----+~~
2448 addresses: 0 @dots{}
2455 \line{\it Partial program \#1: \hfil}
2456 \line{\ibox{2.5cm}{\tt text}\ibox{2cm}{\tt data}\ibox{1cm}{\tt bss}\hfil}
2457 \line{\boxit{2.5cm}{\tt ttttt}\boxit{2cm}{\tt dddd}\boxit{1cm}{\tt 00}\hfil}
2459 \line{\it Partial program \#2: \hfil}
2460 \line{\ibox{1cm}{\tt text}\ibox{1.5cm}{\tt data}\ibox{1cm}{\tt bss}\hfil}
2461 \line{\boxit{1cm}{\tt TTT}\boxit{1.5cm}{\tt DDDD}\boxit{1cm}{\tt 000}\hfil}
2463 \line{\it linked program: \hfil}
2464 \line{\ibox{.5cm}{}\ibox{1cm}{\tt text}\ibox{2.5cm}{}\ibox{.75cm}{}\ibox{2cm}{\tt data}\ibox{1.5cm}{}\ibox{2cm}{\tt bss}\hfil}
2465 \line{\boxit{.5cm}{}\boxit{1cm}{\tt TTT}\boxit{2.5cm}{\tt
2466 ttttt}\boxit{.75cm}{}\boxit{2cm}{\tt dddd}\boxit{1.5cm}{\tt
2467 DDDD}\boxit{2cm}{\tt 00000}\ \dots\hfil}
2469 \line{\it addresses: \hfil}
2473 @c END TEXI2ROFF-KILL
2476 @section Assembler Internal Sections
2478 @cindex internal assembler sections
2479 @cindex sections in messages, internal
2480 These sections are meant only for the internal use of @code{@value{AS}}. They
2481 have no meaning at run-time. You do not really need to know about these
2482 sections for most purposes; but they can be mentioned in @code{@value{AS}}
2483 warning messages, so it might be helpful to have an idea of their
2484 meanings to @code{@value{AS}}. These sections are used to permit the
2485 value of every expression in your assembly language program to be a
2486 section-relative address.
2489 @cindex assembler internal logic error
2490 @item ASSEMBLER-INTERNAL-LOGIC-ERROR!
2491 An internal assembler logic error has been found. This means there is a
2492 bug in the assembler.
2494 @cindex expr (internal section)
2496 The assembler stores complex expression internally as combinations of
2497 symbols. When it needs to represent an expression as a symbol, it puts
2498 it in the expr section.
2500 @c FIXME item transfer[t] vector preload
2501 @c FIXME item transfer[t] vector postload
2502 @c FIXME item register
2506 @section Sub-Sections
2508 @cindex numbered subsections
2509 @cindex grouping data
2515 fall into two sections: text and data.
2517 You may have separate groups of
2519 data in named sections
2523 data in named sections
2529 that you want to end up near to each other in the object file, even though they
2530 are not contiguous in the assembler source. @code{@value{AS}} allows you to
2531 use @dfn{subsections} for this purpose. Within each section, there can be
2532 numbered subsections with values from 0 to 8192. Objects assembled into the
2533 same subsection go into the object file together with other objects in the same
2534 subsection. For example, a compiler might want to store constants in the text
2535 section, but might not want to have them interspersed with the program being
2536 assembled. In this case, the compiler could issue a @samp{.text 0} before each
2537 section of code being output, and a @samp{.text 1} before each group of
2538 constants being output.
2540 Subsections are optional. If you do not use subsections, everything
2541 goes in subsection number zero.
2544 Each subsection is zero-padded up to a multiple of four bytes.
2545 (Subsections may be padded a different amount on different flavors
2546 of @code{@value{AS}}.)
2550 On the H8/300 and H8/500 platforms, each subsection is zero-padded to a word
2551 boundary (two bytes).
2552 The same is true on the Hitachi SH.
2555 @c FIXME section padding (alignment)?
2556 @c Rich Pixley says padding here depends on target obj code format; that
2557 @c doesn't seem particularly useful to say without further elaboration,
2558 @c so for now I say nothing about it. If this is a generic BFD issue,
2559 @c these paragraphs might need to vanish from this manual, and be
2560 @c discussed in BFD chapter of binutils (or some such).
2563 On the AMD 29K family, no particular padding is added to section or
2564 subsection sizes; @value{AS} forces no alignment on this platform.
2568 Subsections appear in your object file in numeric order, lowest numbered
2569 to highest. (All this to be compatible with other people's assemblers.)
2570 The object file contains no representation of subsections; @code{@value{LD}} and
2571 other programs that manipulate object files see no trace of them.
2572 They just see all your text subsections as a text section, and all your
2573 data subsections as a data section.
2575 To specify which subsection you want subsequent statements assembled
2576 into, use a numeric argument to specify it, in a @samp{.text
2577 @var{expression}} or a @samp{.data @var{expression}} statement.
2580 When generating COFF output, you
2585 can also use an extra subsection
2586 argument with arbitrary named sections: @samp{.section @var{name},
2589 @var{Expression} should be an absolute expression.
2590 (@xref{Expressions}.) If you just say @samp{.text} then @samp{.text 0}
2591 is assumed. Likewise @samp{.data} means @samp{.data 0}. Assembly
2592 begins in @code{text 0}. For instance:
2594 .text 0 # The default subsection is text 0 anyway.
2595 .ascii "This lives in the first text subsection. *"
2597 .ascii "But this lives in the second text subsection."
2599 .ascii "This lives in the data section,"
2600 .ascii "in the first data subsection."
2602 .ascii "This lives in the first text section,"
2603 .ascii "immediately following the asterisk (*)."
2606 Each section has a @dfn{location counter} incremented by one for every byte
2607 assembled into that section. Because subsections are merely a convenience
2608 restricted to @code{@value{AS}} there is no concept of a subsection location
2609 counter. There is no way to directly manipulate a location counter---but the
2610 @code{.align} directive changes it, and any label definition captures its
2611 current value. The location counter of the section where statements are being
2612 assembled is said to be the @dfn{active} location counter.
2615 @section bss Section
2618 @cindex common variable storage
2619 The bss section is used for local common variable storage.
2620 You may allocate address space in the bss section, but you may
2621 not dictate data to load into it before your program executes. When
2622 your program starts running, all the contents of the bss
2623 section are zeroed bytes.
2625 The @code{.lcomm} pseudo-op defines a symbol in the bss section; see
2626 @ref{Lcomm,,@code{.lcomm}}.
2628 The @code{.comm} pseudo-op may be used to declare a common symbol, which is
2629 another form of uninitialized symbol; see @xref{Comm,,@code{.comm}}.
2632 When assembling for a target which supports multiple sections, such as ELF or
2633 COFF, you may switch into the @code{.bss} section and define symbols as usual;
2634 see @ref{Section,,@code{.section}}. You may only assemble zero values into the
2635 section. Typically the section will only contain symbol definitions and
2636 @code{.skip} directives (@pxref{Skip,,@code{.skip}}).
2643 Symbols are a central concept: the programmer uses symbols to name
2644 things, the linker uses symbols to link, and the debugger uses symbols
2648 @cindex debuggers, and symbol order
2649 @emph{Warning:} @code{@value{AS}} does not place symbols in the object file in
2650 the same order they were declared. This may break some debuggers.
2655 * Setting Symbols:: Giving Symbols Other Values
2656 * Symbol Names:: Symbol Names
2657 * Dot:: The Special Dot Symbol
2658 * Symbol Attributes:: Symbol Attributes
2665 A @dfn{label} is written as a symbol immediately followed by a colon
2666 @samp{:}. The symbol then represents the current value of the
2667 active location counter, and is, for example, a suitable instruction
2668 operand. You are warned if you use the same symbol to represent two
2669 different locations: the first definition overrides any other
2673 On the HPPA, the usual form for a label need not be immediately followed by a
2674 colon, but instead must start in column zero. Only one label may be defined on
2675 a single line. To work around this, the HPPA version of @code{@value{AS}} also
2676 provides a special directive @code{.label} for defining labels more flexibly.
2679 @node Setting Symbols
2680 @section Giving Symbols Other Values
2682 @cindex assigning values to symbols
2683 @cindex symbol values, assigning
2684 A symbol can be given an arbitrary value by writing a symbol, followed
2685 by an equals sign @samp{=}, followed by an expression
2686 (@pxref{Expressions}). This is equivalent to using the @code{.set}
2687 directive. @xref{Set,,@code{.set}}.
2690 @section Symbol Names
2692 @cindex symbol names
2693 @cindex names, symbol
2694 @ifclear SPECIAL-SYMS
2695 Symbol names begin with a letter or with one of @samp{._}. On most
2696 machines, you can also use @code{$} in symbol names; exceptions are
2697 noted in @ref{Machine Dependencies}. That character may be followed by any
2698 string of digits, letters, dollar signs (unless otherwise noted in
2699 @ref{Machine Dependencies}), and underscores.
2702 For the AMD 29K family, @samp{?} is also allowed in the
2703 body of a symbol name, though not at its beginning.
2708 Symbol names begin with a letter or with one of @samp{._}. On the
2710 H8/500, you can also use @code{$} in symbol names. That character may
2711 be followed by any string of digits, letters, dollar signs (save on the
2712 H8/300), and underscores.
2716 Case of letters is significant: @code{foo} is a different symbol name
2719 Each symbol has exactly one name. Each name in an assembly language program
2720 refers to exactly one symbol. You may use that symbol name any number of times
2723 @subheading Local Symbol Names
2725 @cindex local symbol names
2726 @cindex symbol names, local
2727 @cindex temporary symbol names
2728 @cindex symbol names, temporary
2729 Local symbols help compilers and programmers use names temporarily.
2730 There are ten local symbol names, which are re-used throughout the
2731 program. You may refer to them using the names @samp{0} @samp{1}
2732 @dots{} @samp{9}. To define a local symbol, write a label of the form
2733 @samp{@b{N}:} (where @b{N} represents any digit). To refer to the most
2734 recent previous definition of that symbol write @samp{@b{N}b}, using the
2735 same digit as when you defined the label. To refer to the next
2736 definition of a local label, write @samp{@b{N}f}---where @b{N} gives you
2737 a choice of 10 forward references. The @samp{b} stands for
2738 ``backwards'' and the @samp{f} stands for ``forwards''.
2740 Local symbols are not emitted by the current @sc{gnu} C compiler.
2742 There is no restriction on how you can use these labels, but
2743 remember that at any point in the assembly you can refer to at most
2744 10 prior local labels and to at most 10 forward local labels.
2746 Local symbol names are only a notation device. They are immediately
2747 transformed into more conventional symbol names before the assembler
2748 uses them. The symbol names stored in the symbol table, appearing in
2749 error messages and optionally emitted to the object file have these
2754 All local labels begin with @samp{L}. Normally both @code{@value{AS}} and
2755 @code{@value{LD}} forget symbols that start with @samp{L}. These labels are
2756 used for symbols you are never intended to see. If you use the
2757 @samp{-L} option then @code{@value{AS}} retains these symbols in the
2758 object file. If you also instruct @code{@value{LD}} to retain these symbols,
2759 you may use them in debugging.
2762 If the label is written @samp{0:} then the digit is @samp{0}.
2763 If the label is written @samp{1:} then the digit is @samp{1}.
2764 And so on up through @samp{9:}.
2767 This unusual character is included so you do not accidentally invent
2768 a symbol of the same name. The character has ASCII value
2771 @item @emph{ordinal number}
2772 This is a serial number to keep the labels distinct. The first
2773 @samp{0:} gets the number @samp{1}; The 15th @samp{0:} gets the
2774 number @samp{15}; @emph{etc.}. Likewise for the other labels @samp{1:}
2778 For instance, the first @code{1:} is named @code{L1@kbd{C-A}1}, the 44th
2779 @code{3:} is named @code{L3@kbd{C-A}44}.
2782 @section The Special Dot Symbol
2784 @cindex dot (symbol)
2785 @cindex @code{.} (symbol)
2786 @cindex current address
2787 @cindex location counter
2788 The special symbol @samp{.} refers to the current address that
2789 @code{@value{AS}} is assembling into. Thus, the expression @samp{melvin:
2790 .long .} defines @code{melvin} to contain its own address.
2791 Assigning a value to @code{.} is treated the same as a @code{.org}
2792 directive. Thus, the expression @samp{.=.+4} is the same as saying
2793 @ifclear no-space-dir
2802 @node Symbol Attributes
2803 @section Symbol Attributes
2805 @cindex symbol attributes
2806 @cindex attributes, symbol
2807 Every symbol has, as well as its name, the attributes ``Value'' and
2808 ``Type''. Depending on output format, symbols can also have auxiliary
2811 The detailed definitions are in @file{a.out.h}.
2814 If you use a symbol without defining it, @code{@value{AS}} assumes zero for
2815 all these attributes, and probably won't warn you. This makes the
2816 symbol an externally defined symbol, which is generally what you
2820 * Symbol Value:: Value
2821 * Symbol Type:: Type
2824 * a.out Symbols:: Symbol Attributes: @code{a.out}
2828 * a.out Symbols:: Symbol Attributes: @code{a.out}
2831 * a.out Symbols:: Symbol Attributes: @code{a.out}, @code{b.out}
2836 * COFF Symbols:: Symbol Attributes for COFF
2839 * SOM Symbols:: Symbol Attributes for SOM
2846 @cindex value of a symbol
2847 @cindex symbol value
2848 The value of a symbol is (usually) 32 bits. For a symbol which labels a
2849 location in the text, data, bss or absolute sections the value is the
2850 number of addresses from the start of that section to the label.
2851 Naturally for text, data and bss sections the value of a symbol changes
2852 as @code{@value{LD}} changes section base addresses during linking. Absolute
2853 symbols' values do not change during linking: that is why they are
2856 The value of an undefined symbol is treated in a special way. If it is
2857 0 then the symbol is not defined in this assembler source file, and
2858 @code{@value{LD}} tries to determine its value from other files linked into the
2859 same program. You make this kind of symbol simply by mentioning a symbol
2860 name without defining it. A non-zero value represents a @code{.comm}
2861 common declaration. The value is how much common storage to reserve, in
2862 bytes (addresses). The symbol refers to the first address of the
2868 @cindex type of a symbol
2870 The type attribute of a symbol contains relocation (section)
2871 information, any flag settings indicating that a symbol is external, and
2872 (optionally), other information for linkers and debuggers. The exact
2873 format depends on the object-code output format in use.
2878 @c The following avoids a "widow" subsection title. @group would be
2879 @c better if it were available outside examples.
2882 @subsection Symbol Attributes: @code{a.out}, @code{b.out}
2884 @cindex @code{b.out} symbol attributes
2885 @cindex symbol attributes, @code{b.out}
2886 These symbol attributes appear only when @code{@value{AS}} is configured for
2887 one of the Berkeley-descended object output formats---@code{a.out} or
2893 @subsection Symbol Attributes: @code{a.out}
2895 @cindex @code{a.out} symbol attributes
2896 @cindex symbol attributes, @code{a.out}
2902 @subsection Symbol Attributes: @code{a.out}
2904 @cindex @code{a.out} symbol attributes
2905 @cindex symbol attributes, @code{a.out}
2909 * Symbol Desc:: Descriptor
2910 * Symbol Other:: Other
2914 @subsubsection Descriptor
2916 @cindex descriptor, of @code{a.out} symbol
2917 This is an arbitrary 16-bit value. You may establish a symbol's
2918 descriptor value by using a @code{.desc} statement
2919 (@pxref{Desc,,@code{.desc}}). A descriptor value means nothing to
2923 @subsubsection Other
2925 @cindex other attribute, of @code{a.out} symbol
2926 This is an arbitrary 8-bit value. It means nothing to @code{@value{AS}}.
2931 @subsection Symbol Attributes for COFF
2933 @cindex COFF symbol attributes
2934 @cindex symbol attributes, COFF
2936 The COFF format supports a multitude of auxiliary symbol attributes;
2937 like the primary symbol attributes, they are set between @code{.def} and
2938 @code{.endef} directives.
2940 @subsubsection Primary Attributes
2942 @cindex primary attributes, COFF symbols
2943 The symbol name is set with @code{.def}; the value and type,
2944 respectively, with @code{.val} and @code{.type}.
2946 @subsubsection Auxiliary Attributes
2948 @cindex auxiliary attributes, COFF symbols
2949 The @code{@value{AS}} directives @code{.dim}, @code{.line}, @code{.scl},
2950 @code{.size}, and @code{.tag} can generate auxiliary symbol table
2951 information for COFF.
2956 @subsection Symbol Attributes for SOM
2958 @cindex SOM symbol attributes
2959 @cindex symbol attributes, SOM
2961 The SOM format for the HPPA supports a multitude of symbol attributes set with
2962 the @code{.EXPORT} and @code{.IMPORT} directives.
2964 The attributes are described in @cite{HP9000 Series 800 Assembly
2965 Language Reference Manual} (HP 92432-90001) under the @code{IMPORT} and
2966 @code{EXPORT} assembler directive documentation.
2970 @chapter Expressions
2974 @cindex numeric values
2975 An @dfn{expression} specifies an address or numeric value.
2976 Whitespace may precede and/or follow an expression.
2978 The result of an expression must be an absolute number, or else an offset into
2979 a particular section. If an expression is not absolute, and there is not
2980 enough information when @code{@value{AS}} sees the expression to know its
2981 section, a second pass over the source program might be necessary to interpret
2982 the expression---but the second pass is currently not implemented.
2983 @code{@value{AS}} aborts with an error message in this situation.
2986 * Empty Exprs:: Empty Expressions
2987 * Integer Exprs:: Integer Expressions
2991 @section Empty Expressions
2993 @cindex empty expressions
2994 @cindex expressions, empty
2995 An empty expression has no value: it is just whitespace or null.
2996 Wherever an absolute expression is required, you may omit the
2997 expression, and @code{@value{AS}} assumes a value of (absolute) 0. This
2998 is compatible with other assemblers.
3001 @section Integer Expressions
3003 @cindex integer expressions
3004 @cindex expressions, integer
3005 An @dfn{integer expression} is one or more @emph{arguments} delimited
3006 by @emph{operators}.
3009 * Arguments:: Arguments
3010 * Operators:: Operators
3011 * Prefix Ops:: Prefix Operators
3012 * Infix Ops:: Infix Operators
3016 @subsection Arguments
3018 @cindex expression arguments
3019 @cindex arguments in expressions
3020 @cindex operands in expressions
3021 @cindex arithmetic operands
3022 @dfn{Arguments} are symbols, numbers or subexpressions. In other
3023 contexts arguments are sometimes called ``arithmetic operands''. In
3024 this manual, to avoid confusing them with the ``instruction operands'' of
3025 the machine language, we use the term ``argument'' to refer to parts of
3026 expressions only, reserving the word ``operand'' to refer only to machine
3027 instruction operands.
3029 Symbols are evaluated to yield @{@var{section} @var{NNN}@} where
3030 @var{section} is one of text, data, bss, absolute,
3031 or undefined. @var{NNN} is a signed, 2's complement 32 bit
3034 Numbers are usually integers.
3036 A number can be a flonum or bignum. In this case, you are warned
3037 that only the low order 32 bits are used, and @code{@value{AS}} pretends
3038 these 32 bits are an integer. You may write integer-manipulating
3039 instructions that act on exotic constants, compatible with other
3042 @cindex subexpressions
3043 Subexpressions are a left parenthesis @samp{(} followed by an integer
3044 expression, followed by a right parenthesis @samp{)}; or a prefix
3045 operator followed by an argument.
3048 @subsection Operators
3050 @cindex operators, in expressions
3051 @cindex arithmetic functions
3052 @cindex functions, in expressions
3053 @dfn{Operators} are arithmetic functions, like @code{+} or @code{%}. Prefix
3054 operators are followed by an argument. Infix operators appear
3055 between their arguments. Operators may be preceded and/or followed by
3059 @subsection Prefix Operator
3061 @cindex prefix operators
3062 @code{@value{AS}} has the following @dfn{prefix operators}. They each take
3063 one argument, which must be absolute.
3065 @c the tex/end tex stuff surrounding this small table is meant to make
3066 @c it align, on the printed page, with the similar table in the next
3067 @c section (which is inside an enumerate).
3069 \global\advance\leftskip by \itemindent
3074 @dfn{Negation}. Two's complement negation.
3076 @dfn{Complementation}. Bitwise not.
3080 \global\advance\leftskip by -\itemindent
3084 @subsection Infix Operators
3086 @cindex infix operators
3087 @cindex operators, permitted arguments
3088 @dfn{Infix operators} take two arguments, one on either side. Operators
3089 have precedence, but operations with equal precedence are performed left
3090 to right. Apart from @code{+} or @code{-}, both arguments must be
3091 absolute, and the result is absolute.
3094 @cindex operator precedence
3095 @cindex precedence of operators
3102 @dfn{Multiplication}.
3105 @dfn{Division}. Truncation is the same as the C operator @samp{/}
3112 @dfn{Shift Left}. Same as the C operator @samp{<<}.
3116 @dfn{Shift Right}. Same as the C operator @samp{>>}.
3120 Intermediate precedence
3125 @dfn{Bitwise Inclusive Or}.
3131 @dfn{Bitwise Exclusive Or}.
3134 @dfn{Bitwise Or Not}.
3141 @cindex addition, permitted arguments
3142 @cindex plus, permitted arguments
3143 @cindex arguments for addition
3145 @dfn{Addition}. If either argument is absolute, the result has the section of
3146 the other argument. You may not add together arguments from different
3149 @cindex subtraction, permitted arguments
3150 @cindex minus, permitted arguments
3151 @cindex arguments for subtraction
3153 @dfn{Subtraction}. If the right argument is absolute, the
3154 result has the section of the left argument.
3155 If both arguments are in the same section, the result is absolute.
3156 You may not subtract arguments from different sections.
3157 @c FIXME is there still something useful to say about undefined - undefined ?
3161 In short, it's only meaningful to add or subtract the @emph{offsets} in an
3162 address; you can only have a defined section in one of the two arguments.
3165 @chapter Assembler Directives
3167 @cindex directives, machine independent
3168 @cindex pseudo-ops, machine independent
3169 @cindex machine independent directives
3170 All assembler directives have names that begin with a period (@samp{.}).
3171 The rest of the name is letters, usually in lower case.
3173 This chapter discusses directives that are available regardless of the
3174 target machine configuration for the @sc{gnu} assembler.
3176 Some machine configurations provide additional directives.
3177 @xref{Machine Dependencies}.
3180 @ifset machine-directives
3181 @xref{Machine Dependencies} for additional directives.
3186 * Abort:: @code{.abort}
3188 * ABORT:: @code{.ABORT}
3191 * Align:: @code{.align @var{abs-expr} , @var{abs-expr}}
3192 * Ascii:: @code{.ascii "@var{string}"}@dots{}
3193 * Asciz:: @code{.asciz "@var{string}"}@dots{}
3194 * Balign:: @code{.balign @var{abs-expr} , @var{abs-expr}}
3195 * Byte:: @code{.byte @var{expressions}}
3196 * Comm:: @code{.comm @var{symbol} , @var{length} }
3197 * Data:: @code{.data @var{subsection}}
3199 * Def:: @code{.def @var{name}}
3202 * Desc:: @code{.desc @var{symbol}, @var{abs-expression}}
3208 * Double:: @code{.double @var{flonums}}
3209 * Eject:: @code{.eject}
3210 * Else:: @code{.else}
3211 * Elseif:: @code{.elseif}
3214 * Endef:: @code{.endef}
3217 * Endfunc:: @code{.endfunc}
3218 * Endif:: @code{.endif}
3219 * Equ:: @code{.equ @var{symbol}, @var{expression}}
3220 * Equiv:: @code{.equiv @var{symbol}, @var{expression}}
3222 * Exitm:: @code{.exitm}
3223 * Extern:: @code{.extern}
3224 * Fail:: @code{.fail}
3225 @ifclear no-file-dir
3226 * File:: @code{.file @var{string}}
3229 * Fill:: @code{.fill @var{repeat} , @var{size} , @var{value}}
3230 * Float:: @code{.float @var{flonums}}
3231 * Func:: @code{.func}
3232 * Global:: @code{.global @var{symbol}}, @code{.globl @var{symbol}}
3234 * Hidden:: @code{.hidden @var{names}}
3237 * hword:: @code{.hword @var{expressions}}
3238 * Ident:: @code{.ident}
3239 * If:: @code{.if @var{absolute expression}}
3240 * Include:: @code{.include "@var{file}"}
3241 * Int:: @code{.int @var{expressions}}
3243 * Internal:: @code{.internal @var{names}}
3246 * Irp:: @code{.irp @var{symbol},@var{values}}@dots{}
3247 * Irpc:: @code{.irpc @var{symbol},@var{values}}@dots{}
3248 * Lcomm:: @code{.lcomm @var{symbol} , @var{length}}
3249 * Lflags:: @code{.lflags}
3250 @ifclear no-line-dir
3251 * Line:: @code{.line @var{line-number}}
3254 * Ln:: @code{.ln @var{line-number}}
3255 * Linkonce:: @code{.linkonce [@var{type}]}
3256 * List:: @code{.list}
3257 * Long:: @code{.long @var{expressions}}
3259 * Lsym:: @code{.lsym @var{symbol}, @var{expression}}
3262 * Macro:: @code{.macro @var{name} @var{args}}@dots{}
3263 * MRI:: @code{.mri @var{val}}
3264 * Nolist:: @code{.nolist}
3265 * Octa:: @code{.octa @var{bignums}}
3266 * Org:: @code{.org @var{new-lc} , @var{fill}}
3267 * P2align:: @code{.p2align @var{abs-expr} , @var{abs-expr}}
3269 * PopSection:: @code{.popsection}
3270 * Previous:: @code{.previous}
3273 * Print:: @code{.print @var{string}}
3275 * Protected:: @code{.protected @var{names}}
3278 * Psize:: @code{.psize @var{lines}, @var{columns}}
3279 * Purgem:: @code{.purgem @var{name}}
3281 * PushSection:: @code{.pushsection @var{name}}
3284 * Quad:: @code{.quad @var{bignums}}
3285 * Rept:: @code{.rept @var{count}}
3286 * Sbttl:: @code{.sbttl "@var{subheading}"}
3288 * Scl:: @code{.scl @var{class}}
3289 * Section:: @code{.section @var{name}, @var{subsection}}
3292 * Set:: @code{.set @var{symbol}, @var{expression}}
3293 * Short:: @code{.short @var{expressions}}
3294 * Single:: @code{.single @var{flonums}}
3295 * Size:: @code{.size [@var{name} , @var{expression}]}
3296 * Skip:: @code{.skip @var{size} , @var{fill}}
3297 * Sleb128:: @code{.sleb128 @var{expressions}}
3298 * Space:: @code{.space @var{size} , @var{fill}}
3300 * Stab:: @code{.stabd, .stabn, .stabs}
3303 * String:: @code{.string "@var{str}"}
3304 * Struct:: @code{.struct @var{expression}}
3306 * SubSection:: @code{.subsection}
3307 * Symver:: @code{.symver @var{name},@var{name2@@nodename}}
3311 * Tag:: @code{.tag @var{structname}}
3314 * Text:: @code{.text @var{subsection}}
3315 * Title:: @code{.title "@var{heading}"}
3316 * Type:: @code{.type <@var{int} | @var{name} , @var{type description}>}
3317 * Uleb128:: @code{.uleb128 @var{expressions}}
3319 * Val:: @code{.val @var{addr}}
3323 * Version:: @code{.version "@var{string}"}
3324 * VTableEntry:: @code{.vtable_entry @var{table}, @var{offset}}
3325 * VTableInherit:: @code{.vtable_inherit @var{child}, @var{parent}}
3326 * Weak:: @code{.weak @var{names}}
3329 * Word:: @code{.word @var{expressions}}
3330 * Deprecated:: Deprecated Directives
3334 @section @code{.abort}
3336 @cindex @code{abort} directive
3337 @cindex stopping the assembly
3338 This directive stops the assembly immediately. It is for
3339 compatibility with other assemblers. The original idea was that the
3340 assembly language source would be piped into the assembler. If the sender
3341 of the source quit, it could use this directive tells @code{@value{AS}} to
3342 quit also. One day @code{.abort} will not be supported.
3346 @section @code{.ABORT}
3348 @cindex @code{ABORT} directive
3349 When producing COFF output, @code{@value{AS}} accepts this directive as a
3350 synonym for @samp{.abort}.
3353 When producing @code{b.out} output, @code{@value{AS}} accepts this directive,
3359 @section @code{.align @var{abs-expr}, @var{abs-expr}, @var{abs-expr}}
3361 @cindex padding the location counter
3362 @cindex @code{align} directive
3363 Pad the location counter (in the current subsection) to a particular storage
3364 boundary. The first expression (which must be absolute) is the alignment
3365 required, as described below.
3367 The second expression (also absolute) gives the fill value to be stored in the
3368 padding bytes. It (and the comma) may be omitted. If it is omitted, the
3369 padding bytes are normally zero. However, on some systems, if the section is
3370 marked as containing code and the fill value is omitted, the space is filled
3371 with no-op instructions.
3373 The third expression is also absolute, and is also optional. If it is present,
3374 it is the maximum number of bytes that should be skipped by this alignment
3375 directive. If doing the alignment would require skipping more bytes than the
3376 specified maximum, then the alignment is not done at all. You can omit the
3377 fill value (the second argument) entirely by simply using two commas after the
3378 required alignment; this can be useful if you want the alignment to be filled
3379 with no-op instructions when appropriate.
3381 The way the required alignment is specified varies from system to system.
3382 For the a29k, hppa, m68k, m88k, w65, sparc, and Hitachi SH, and i386 using ELF
3384 the first expression is the
3385 alignment request in bytes. For example @samp{.align 8} advances
3386 the location counter until it is a multiple of 8. If the location counter
3387 is already a multiple of 8, no change is needed.
3389 For other systems, including the i386 using a.out format, and the arm and
3390 strongarm, it is the
3391 number of low-order zero bits the location counter must have after
3392 advancement. For example @samp{.align 3} advances the location
3393 counter until it a multiple of 8. If the location counter is already a
3394 multiple of 8, no change is needed.
3396 This inconsistency is due to the different behaviors of the various
3397 native assemblers for these systems which GAS must emulate.
3398 GAS also provides @code{.balign} and @code{.p2align} directives,
3399 described later, which have a consistent behavior across all
3400 architectures (but are specific to GAS).
3403 @section @code{.ascii "@var{string}"}@dots{}
3405 @cindex @code{ascii} directive
3406 @cindex string literals
3407 @code{.ascii} expects zero or more string literals (@pxref{Strings})
3408 separated by commas. It assembles each string (with no automatic
3409 trailing zero byte) into consecutive addresses.
3412 @section @code{.asciz "@var{string}"}@dots{}
3414 @cindex @code{asciz} directive
3415 @cindex zero-terminated strings
3416 @cindex null-terminated strings
3417 @code{.asciz} is just like @code{.ascii}, but each string is followed by
3418 a zero byte. The ``z'' in @samp{.asciz} stands for ``zero''.
3421 @section @code{.balign[wl] @var{abs-expr}, @var{abs-expr}, @var{abs-expr}}
3423 @cindex padding the location counter given number of bytes
3424 @cindex @code{balign} directive
3425 Pad the location counter (in the current subsection) to a particular
3426 storage boundary. The first expression (which must be absolute) is the
3427 alignment request in bytes. For example @samp{.balign 8} advances
3428 the location counter until it is a multiple of 8. If the location counter
3429 is already a multiple of 8, no change is needed.
3431 The second expression (also absolute) gives the fill value to be stored in the
3432 padding bytes. It (and the comma) may be omitted. If it is omitted, the
3433 padding bytes are normally zero. However, on some systems, if the section is
3434 marked as containing code and the fill value is omitted, the space is filled
3435 with no-op instructions.
3437 The third expression is also absolute, and is also optional. If it is present,
3438 it is the maximum number of bytes that should be skipped by this alignment
3439 directive. If doing the alignment would require skipping more bytes than the
3440 specified maximum, then the alignment is not done at all. You can omit the
3441 fill value (the second argument) entirely by simply using two commas after the
3442 required alignment; this can be useful if you want the alignment to be filled
3443 with no-op instructions when appropriate.
3445 @cindex @code{balignw} directive
3446 @cindex @code{balignl} directive
3447 The @code{.balignw} and @code{.balignl} directives are variants of the
3448 @code{.balign} directive. The @code{.balignw} directive treats the fill
3449 pattern as a two byte word value. The @code{.balignl} directives treats the
3450 fill pattern as a four byte longword value. For example, @code{.balignw
3451 4,0x368d} will align to a multiple of 4. If it skips two bytes, they will be
3452 filled in with the value 0x368d (the exact placement of the bytes depends upon
3453 the endianness of the processor). If it skips 1 or 3 bytes, the fill value is
3457 @section @code{.byte @var{expressions}}
3459 @cindex @code{byte} directive
3460 @cindex integers, one byte
3461 @code{.byte} expects zero or more expressions, separated by commas.
3462 Each expression is assembled into the next byte.
3465 @section @code{.comm @var{symbol} , @var{length} }
3467 @cindex @code{comm} directive
3468 @cindex symbol, common
3469 @code{.comm} declares a common symbol named @var{symbol}. When linking, a
3470 common symbol in one object file may be merged with a defined or common symbol
3471 of the same name in another object file. If @code{@value{LD}} does not see a
3472 definition for the symbol--just one or more common symbols--then it will
3473 allocate @var{length} bytes of uninitialized memory. @var{length} must be an
3474 absolute expression. If @code{@value{LD}} sees multiple common symbols with
3475 the same name, and they do not all have the same size, it will allocate space
3476 using the largest size.
3479 When using ELF, the @code{.comm} directive takes an optional third argument.
3480 This is the desired alignment of the symbol, specified as a byte boundary (for
3481 example, an alignment of 16 means that the least significant 4 bits of the
3482 address should be zero). The alignment must be an absolute expression, and it
3483 must be a power of two. If @code{@value{LD}} allocates uninitialized memory
3484 for the common symbol, it will use the alignment when placing the symbol. If
3485 no alignment is specified, @code{@value{AS}} will set the alignment to the
3486 largest power of two less than or equal to the size of the symbol, up to a
3491 The syntax for @code{.comm} differs slightly on the HPPA. The syntax is
3492 @samp{@var{symbol} .comm, @var{length}}; @var{symbol} is optional.
3496 @section @code{.data @var{subsection}}
3498 @cindex @code{data} directive
3499 @code{.data} tells @code{@value{AS}} to assemble the following statements onto the
3500 end of the data subsection numbered @var{subsection} (which is an
3501 absolute expression). If @var{subsection} is omitted, it defaults
3506 @section @code{.def @var{name}}
3508 @cindex @code{def} directive
3509 @cindex COFF symbols, debugging
3510 @cindex debugging COFF symbols
3511 Begin defining debugging information for a symbol @var{name}; the
3512 definition extends until the @code{.endef} directive is encountered.
3515 This directive is only observed when @code{@value{AS}} is configured for COFF
3516 format output; when producing @code{b.out}, @samp{.def} is recognized,
3523 @section @code{.desc @var{symbol}, @var{abs-expression}}
3525 @cindex @code{desc} directive
3526 @cindex COFF symbol descriptor
3527 @cindex symbol descriptor, COFF
3528 This directive sets the descriptor of the symbol (@pxref{Symbol Attributes})
3529 to the low 16 bits of an absolute expression.
3532 The @samp{.desc} directive is not available when @code{@value{AS}} is
3533 configured for COFF output; it is only for @code{a.out} or @code{b.out}
3534 object format. For the sake of compatibility, @code{@value{AS}} accepts
3535 it, but produces no output, when configured for COFF.
3541 @section @code{.dim}
3543 @cindex @code{dim} directive
3544 @cindex COFF auxiliary symbol information
3545 @cindex auxiliary symbol information, COFF
3546 This directive is generated by compilers to include auxiliary debugging
3547 information in the symbol table. It is only permitted inside
3548 @code{.def}/@code{.endef} pairs.
3551 @samp{.dim} is only meaningful when generating COFF format output; when
3552 @code{@value{AS}} is generating @code{b.out}, it accepts this directive but
3558 @section @code{.double @var{flonums}}
3560 @cindex @code{double} directive
3561 @cindex floating point numbers (double)
3562 @code{.double} expects zero or more flonums, separated by commas. It
3563 assembles floating point numbers.
3565 The exact kind of floating point numbers emitted depends on how
3566 @code{@value{AS}} is configured. @xref{Machine Dependencies}.
3570 On the @value{TARGET} family @samp{.double} emits 64-bit floating-point numbers
3571 in @sc{ieee} format.
3576 @section @code{.eject}
3578 @cindex @code{eject} directive
3579 @cindex new page, in listings
3580 @cindex page, in listings
3581 @cindex listing control: new page
3582 Force a page break at this point, when generating assembly listings.
3585 @section @code{.else}
3587 @cindex @code{else} directive
3588 @code{.else} is part of the @code{@value{AS}} support for conditional
3589 assembly; @pxref{If,,@code{.if}}. It marks the beginning of a section
3590 of code to be assembled if the condition for the preceding @code{.if}
3594 @section @code{.elseif}
3596 @cindex @code{elseif} directive
3597 @code{.elseif} is part of the @code{@value{AS}} support for conditional
3598 assembly; @pxref{If,,@code{.if}}. It is shorthand for beginning a new
3599 @code{.if} block that would otherwise fill the entire @code{.else} section.
3602 @section @code{.end}
3604 @cindex @code{end} directive
3605 @code{.end} marks the end of the assembly file. @code{@value{AS}} does not
3606 process anything in the file past the @code{.end} directive.
3610 @section @code{.endef}
3612 @cindex @code{endef} directive
3613 This directive flags the end of a symbol definition begun with
3617 @samp{.endef} is only meaningful when generating COFF format output; if
3618 @code{@value{AS}} is configured to generate @code{b.out}, it accepts this
3619 directive but ignores it.
3624 @section @code{.endfunc}
3625 @cindex @code{endfunc} directive
3626 @code{.endfunc} marks the end of a function specified with @code{.func}.
3629 @section @code{.endif}
3631 @cindex @code{endif} directive
3632 @code{.endif} is part of the @code{@value{AS}} support for conditional assembly;
3633 it marks the end of a block of code that is only assembled
3634 conditionally. @xref{If,,@code{.if}}.
3637 @section @code{.equ @var{symbol}, @var{expression}}
3639 @cindex @code{equ} directive
3640 @cindex assigning values to symbols
3641 @cindex symbols, assigning values to
3642 This directive sets the value of @var{symbol} to @var{expression}.
3643 It is synonymous with @samp{.set}; @pxref{Set,,@code{.set}}.
3646 The syntax for @code{equ} on the HPPA is
3647 @samp{@var{symbol} .equ @var{expression}}.
3651 @section @code{.equiv @var{symbol}, @var{expression}}
3652 @cindex @code{equiv} directive
3653 The @code{.equiv} directive is like @code{.equ} and @code{.set}, except that
3654 the assembler will signal an error if @var{symbol} is already defined.
3656 Except for the contents of the error message, this is roughly equivalent to
3665 @section @code{.err}
3666 @cindex @code{err} directive
3667 If @code{@value{AS}} assembles a @code{.err} directive, it will print an error
3668 message and, unless the @code{-Z} option was used, it will not generate an
3669 object file. This can be used to signal error an conditionally compiled code.
3672 @section @code{.exitm}
3673 Exit early from the current macro definition. @xref{Macro}.
3676 @section @code{.extern}
3678 @cindex @code{extern} directive
3679 @code{.extern} is accepted in the source program---for compatibility
3680 with other assemblers---but it is ignored. @code{@value{AS}} treats
3681 all undefined symbols as external.
3684 @section @code{.fail @var{expression}}
3686 @cindex @code{fail} directive
3687 Generates an error or a warning. If the value of the @var{expression} is 500
3688 or more, @code{@value{AS}} will print a warning message. If the value is less
3689 than 500, @code{@value{AS}} will print an error message. The message will
3690 include the value of @var{expression}. This can occasionally be useful inside
3691 complex nested macros or conditional assembly.
3693 @ifclear no-file-dir
3695 @section @code{.file @var{string}}
3697 @cindex @code{file} directive
3698 @cindex logical file name
3699 @cindex file name, logical
3700 @code{.file} tells @code{@value{AS}} that we are about to start a new logical
3701 file. @var{string} is the new file name. In general, the filename is
3702 recognized whether or not it is surrounded by quotes @samp{"}; but if you wish
3703 to specify an empty file name, you must give the quotes--@code{""}. This
3704 statement may go away in future: it is only recognized to be compatible with
3705 old @code{@value{AS}} programs.
3707 In some configurations of @code{@value{AS}}, @code{.file} has already been
3708 removed to avoid conflicts with other assemblers. @xref{Machine Dependencies}.
3713 @section @code{.fill @var{repeat} , @var{size} , @var{value}}
3715 @cindex @code{fill} directive
3716 @cindex writing patterns in memory
3717 @cindex patterns, writing in memory
3718 @var{result}, @var{size} and @var{value} are absolute expressions.
3719 This emits @var{repeat} copies of @var{size} bytes. @var{Repeat}
3720 may be zero or more. @var{Size} may be zero or more, but if it is
3721 more than 8, then it is deemed to have the value 8, compatible with
3722 other people's assemblers. The contents of each @var{repeat} bytes
3723 is taken from an 8-byte number. The highest order 4 bytes are
3724 zero. The lowest order 4 bytes are @var{value} rendered in the
3725 byte-order of an integer on the computer @code{@value{AS}} is assembling for.
3726 Each @var{size} bytes in a repetition is taken from the lowest order
3727 @var{size} bytes of this number. Again, this bizarre behavior is
3728 compatible with other people's assemblers.
3730 @var{size} and @var{value} are optional.
3731 If the second comma and @var{value} are absent, @var{value} is
3732 assumed zero. If the first comma and following tokens are absent,
3733 @var{size} is assumed to be 1.
3736 @section @code{.float @var{flonums}}
3738 @cindex floating point numbers (single)
3739 @cindex @code{float} directive
3740 This directive assembles zero or more flonums, separated by commas. It
3741 has the same effect as @code{.single}.
3743 The exact kind of floating point numbers emitted depends on how
3744 @code{@value{AS}} is configured.
3745 @xref{Machine Dependencies}.
3749 On the @value{TARGET} family, @code{.float} emits 32-bit floating point numbers
3750 in @sc{ieee} format.
3755 @section @code{.func @var{name}[,@var{label}]}
3756 @cindex @code{func} directive
3757 @code{.func} emits debugging information to denote function @var{name}, and
3758 is ignored unless the file is assembled with debugging enabled.
3759 Only @samp{--gstabs} is currently supported.
3760 @var{label} is the entry point of the function and if omitted @var{name}
3761 prepended with the @samp{leading char} is used.
3762 @samp{leading char} is usually @code{_} or nothing, depending on the target.
3763 All functions are currently defined to have @code{void} return type.
3764 The function must be terminated with @code{.endfunc}.
3767 @section @code{.global @var{symbol}}, @code{.globl @var{symbol}}
3769 @cindex @code{global} directive
3770 @cindex symbol, making visible to linker
3771 @code{.global} makes the symbol visible to @code{@value{LD}}. If you define
3772 @var{symbol} in your partial program, its value is made available to
3773 other partial programs that are linked with it. Otherwise,
3774 @var{symbol} takes its attributes from a symbol of the same name
3775 from another file linked into the same program.
3777 Both spellings (@samp{.globl} and @samp{.global}) are accepted, for
3778 compatibility with other assemblers.
3781 On the HPPA, @code{.global} is not always enough to make it accessible to other
3782 partial programs. You may need the HPPA-only @code{.EXPORT} directive as well.
3783 @xref{HPPA Directives,, HPPA Assembler Directives}.
3788 @section @code{.hidden @var{names}}
3790 @cindex @code{.hidden} directive
3792 This one of the ELF visibility directives. The other two are
3793 @pxref{Internal,,@code{.internal}} and @pxref{Protected,,@code{.protected}}
3795 This directive overrides the named symbols default visibility (which is set by
3796 their binding: local, global or weak). The directive sets the visibility to
3797 @code{hidden} which means that the symbols are not visible to other components.
3798 Such symbols are always considered to be @code{protected} as well.
3802 @section @code{.hword @var{expressions}}
3804 @cindex @code{hword} directive
3805 @cindex integers, 16-bit
3806 @cindex numbers, 16-bit
3807 @cindex sixteen bit integers
3808 This expects zero or more @var{expressions}, and emits
3809 a 16 bit number for each.
3812 This directive is a synonym for @samp{.short}; depending on the target
3813 architecture, it may also be a synonym for @samp{.word}.
3817 This directive is a synonym for @samp{.short}.
3820 This directive is a synonym for both @samp{.short} and @samp{.word}.
3825 @section @code{.ident}
3827 @cindex @code{ident} directive
3828 This directive is used by some assemblers to place tags in object files.
3829 @code{@value{AS}} simply accepts the directive for source-file
3830 compatibility with such assemblers, but does not actually emit anything
3834 @section @code{.if @var{absolute expression}}
3836 @cindex conditional assembly
3837 @cindex @code{if} directive
3838 @code{.if} marks the beginning of a section of code which is only
3839 considered part of the source program being assembled if the argument
3840 (which must be an @var{absolute expression}) is non-zero. The end of
3841 the conditional section of code must be marked by @code{.endif}
3842 (@pxref{Endif,,@code{.endif}}); optionally, you may include code for the
3843 alternative condition, flagged by @code{.else} (@pxref{Else,,@code{.else}}).
3844 If you have several conditions to check, @code{.elseif} may be used to avoid
3845 nesting blocks if/else within each subsequent @code{.else} block.
3847 The following variants of @code{.if} are also supported:
3849 @cindex @code{ifdef} directive
3850 @item .ifdef @var{symbol}
3851 Assembles the following section of code if the specified @var{symbol}
3854 @cindex @code{ifc} directive
3855 @item .ifc @var{string1},@var{string2}
3856 Assembles the following section of code if the two strings are the same. The
3857 strings may be optionally quoted with single quotes. If they are not quoted,
3858 the first string stops at the first comma, and the second string stops at the
3859 end of the line. Strings which contain whitespace should be quoted. The
3860 string comparison is case sensitive.
3862 @cindex @code{ifeq} directive
3863 @item .ifeq @var{absolute expression}
3864 Assembles the following section of code if the argument is zero.
3866 @cindex @code{ifeqs} directive
3867 @item .ifeqs @var{string1},@var{string2}
3868 Another form of @code{.ifc}. The strings must be quoted using double quotes.
3870 @cindex @code{ifge} directive
3871 @item .ifge @var{absolute expression}
3872 Assembles the following section of code if the argument is greater than or
3875 @cindex @code{ifgt} directive
3876 @item .ifgt @var{absolute expression}
3877 Assembles the following section of code if the argument is greater than zero.
3879 @cindex @code{ifle} directive
3880 @item .ifle @var{absolute expression}
3881 Assembles the following section of code if the argument is less than or equal
3884 @cindex @code{iflt} directive
3885 @item .iflt @var{absolute expression}
3886 Assembles the following section of code if the argument is less than zero.
3888 @cindex @code{ifnc} directive
3889 @item .ifnc @var{string1},@var{string2}.
3890 Like @code{.ifc}, but the sense of the test is reversed: this assembles the
3891 following section of code if the two strings are not the same.
3893 @cindex @code{ifndef} directive
3894 @cindex @code{ifnotdef} directive
3895 @item .ifndef @var{symbol}
3896 @itemx .ifnotdef @var{symbol}
3897 Assembles the following section of code if the specified @var{symbol}
3898 has not been defined. Both spelling variants are equivalent.
3900 @cindex @code{ifne} directive
3901 @item .ifne @var{absolute expression}
3902 Assembles the following section of code if the argument is not equal to zero
3903 (in other words, this is equivalent to @code{.if}).
3905 @cindex @code{ifnes} directive
3906 @item .ifnes @var{string1},@var{string2}
3907 Like @code{.ifeqs}, but the sense of the test is reversed: this assembles the
3908 following section of code if the two strings are not the same.
3912 @section @code{.include "@var{file}"}
3914 @cindex @code{include} directive
3915 @cindex supporting files, including
3916 @cindex files, including
3917 This directive provides a way to include supporting files at specified
3918 points in your source program. The code from @var{file} is assembled as
3919 if it followed the point of the @code{.include}; when the end of the
3920 included file is reached, assembly of the original file continues. You
3921 can control the search paths used with the @samp{-I} command-line option
3922 (@pxref{Invoking,,Command-Line Options}). Quotation marks are required
3926 @section @code{.int @var{expressions}}
3928 @cindex @code{int} directive
3929 @cindex integers, 32-bit
3930 Expect zero or more @var{expressions}, of any section, separated by commas.
3931 For each expression, emit a number that, at run time, is the value of that
3932 expression. The byte order and bit size of the number depends on what kind
3933 of target the assembly is for.
3937 On the H8/500 and most forms of the H8/300, @code{.int} emits 16-bit
3938 integers. On the H8/300H and the Hitachi SH, however, @code{.int} emits
3945 @section @code{.internal @var{names}}
3947 @cindex @code{.internal} directive
3949 This one of the ELF visibility directives. The other two are
3950 @pxref{Hidden,,@code{.hidden}} and @pxref{Protected,,@code{.protected}}
3952 This directive overrides the named symbols default visibility (which is set by
3953 their binding: local, global or weak). The directive sets the visibility to
3954 @code{internal} which means that the symbols are considered to be @code{hidden}
3955 (ie not visible to other components), and that some extra, processor specific
3956 processing must also be performed upon the symbols as well.
3960 @section @code{.irp @var{symbol},@var{values}}@dots{}
3962 @cindex @code{irp} directive
3963 Evaluate a sequence of statements assigning different values to @var{symbol}.
3964 The sequence of statements starts at the @code{.irp} directive, and is
3965 terminated by an @code{.endr} directive. For each @var{value}, @var{symbol} is
3966 set to @var{value}, and the sequence of statements is assembled. If no
3967 @var{value} is listed, the sequence of statements is assembled once, with
3968 @var{symbol} set to the null string. To refer to @var{symbol} within the
3969 sequence of statements, use @var{\symbol}.
3971 For example, assembling
3979 is equivalent to assembling
3988 @section @code{.irpc @var{symbol},@var{values}}@dots{}
3990 @cindex @code{irpc} directive
3991 Evaluate a sequence of statements assigning different values to @var{symbol}.
3992 The sequence of statements starts at the @code{.irpc} directive, and is
3993 terminated by an @code{.endr} directive. For each character in @var{value},
3994 @var{symbol} is set to the character, and the sequence of statements is
3995 assembled. If no @var{value} is listed, the sequence of statements is
3996 assembled once, with @var{symbol} set to the null string. To refer to
3997 @var{symbol} within the sequence of statements, use @var{\symbol}.
3999 For example, assembling
4007 is equivalent to assembling
4016 @section @code{.lcomm @var{symbol} , @var{length}}
4018 @cindex @code{lcomm} directive
4019 @cindex local common symbols
4020 @cindex symbols, local common
4021 Reserve @var{length} (an absolute expression) bytes for a local common
4022 denoted by @var{symbol}. The section and value of @var{symbol} are
4023 those of the new local common. The addresses are allocated in the bss
4024 section, so that at run-time the bytes start off zeroed. @var{Symbol}
4025 is not declared global (@pxref{Global,,@code{.global}}), so is normally
4026 not visible to @code{@value{LD}}.
4029 Some targets permit a third argument to be used with @code{.lcomm}. This
4030 argument specifies the desired alignment of the symbol in the bss section.
4034 The syntax for @code{.lcomm} differs slightly on the HPPA. The syntax is
4035 @samp{@var{symbol} .lcomm, @var{length}}; @var{symbol} is optional.
4039 @section @code{.lflags}
4041 @cindex @code{lflags} directive (ignored)
4042 @code{@value{AS}} accepts this directive, for compatibility with other
4043 assemblers, but ignores it.
4045 @ifclear no-line-dir
4047 @section @code{.line @var{line-number}}
4049 @cindex @code{line} directive
4053 @section @code{.ln @var{line-number}}
4055 @cindex @code{ln} directive
4057 @cindex logical line number
4059 Change the logical line number. @var{line-number} must be an absolute
4060 expression. The next line has that logical line number. Therefore any other
4061 statements on the current line (after a statement separator character) are
4062 reported as on logical line number @var{line-number} @minus{} 1. One day
4063 @code{@value{AS}} will no longer support this directive: it is recognized only
4064 for compatibility with existing assembler programs.
4068 @emph{Warning:} In the AMD29K configuration of @value{AS}, this command is
4069 not available; use the synonym @code{.ln} in that context.
4074 @ifclear no-line-dir
4075 Even though this is a directive associated with the @code{a.out} or
4076 @code{b.out} object-code formats, @code{@value{AS}} still recognizes it
4077 when producing COFF output, and treats @samp{.line} as though it
4078 were the COFF @samp{.ln} @emph{if} it is found outside a
4079 @code{.def}/@code{.endef} pair.
4081 Inside a @code{.def}, @samp{.line} is, instead, one of the directives
4082 used by compilers to generate auxiliary symbol information for
4087 @section @code{.linkonce [@var{type}]}
4089 @cindex @code{linkonce} directive
4090 @cindex common sections
4091 Mark the current section so that the linker only includes a single copy of it.
4092 This may be used to include the same section in several different object files,
4093 but ensure that the linker will only include it once in the final output file.
4094 The @code{.linkonce} pseudo-op must be used for each instance of the section.
4095 Duplicate sections are detected based on the section name, so it should be
4098 This directive is only supported by a few object file formats; as of this
4099 writing, the only object file format which supports it is the Portable
4100 Executable format used on Windows NT.
4102 The @var{type} argument is optional. If specified, it must be one of the
4103 following strings. For example:
4107 Not all types may be supported on all object file formats.
4111 Silently discard duplicate sections. This is the default.
4114 Warn if there are duplicate sections, but still keep only one copy.
4117 Warn if any of the duplicates have different sizes.
4120 Warn if any of the duplicates do not have exactly the same contents.
4124 @section @code{.ln @var{line-number}}
4126 @cindex @code{ln} directive
4127 @ifclear no-line-dir
4128 @samp{.ln} is a synonym for @samp{.line}.
4131 Tell @code{@value{AS}} to change the logical line number. @var{line-number}
4132 must be an absolute expression. The next line has that logical
4133 line number, so any other statements on the current line (after a
4134 statement separator character @code{;}) are reported as on logical
4135 line number @var{line-number} @minus{} 1.
4138 This directive is accepted, but ignored, when @code{@value{AS}} is
4139 configured for @code{b.out}; its effect is only associated with COFF
4145 @section @code{.mri @var{val}}
4147 @cindex @code{mri} directive
4148 @cindex MRI mode, temporarily
4149 If @var{val} is non-zero, this tells @code{@value{AS}} to enter MRI mode. If
4150 @var{val} is zero, this tells @code{@value{AS}} to exit MRI mode. This change
4151 affects code assembled until the next @code{.mri} directive, or until the end
4152 of the file. @xref{M, MRI mode, MRI mode}.
4155 @section @code{.list}
4157 @cindex @code{list} directive
4158 @cindex listing control, turning on
4159 Control (in conjunction with the @code{.nolist} directive) whether or
4160 not assembly listings are generated. These two directives maintain an
4161 internal counter (which is zero initially). @code{.list} increments the
4162 counter, and @code{.nolist} decrements it. Assembly listings are
4163 generated whenever the counter is greater than zero.
4165 By default, listings are disabled. When you enable them (with the
4166 @samp{-a} command line option; @pxref{Invoking,,Command-Line Options}),
4167 the initial value of the listing counter is one.
4170 @section @code{.long @var{expressions}}
4172 @cindex @code{long} directive
4173 @code{.long} is the same as @samp{.int}, @pxref{Int,,@code{.int}}.
4176 @c no one seems to know what this is for or whether this description is
4177 @c what it really ought to do
4179 @section @code{.lsym @var{symbol}, @var{expression}}
4181 @cindex @code{lsym} directive
4182 @cindex symbol, not referenced in assembly
4183 @code{.lsym} creates a new symbol named @var{symbol}, but does not put it in
4184 the hash table, ensuring it cannot be referenced by name during the
4185 rest of the assembly. This sets the attributes of the symbol to be
4186 the same as the expression value:
4188 @var{other} = @var{descriptor} = 0
4189 @var{type} = @r{(section of @var{expression})}
4190 @var{value} = @var{expression}
4193 The new symbol is not flagged as external.
4197 @section @code{.macro}
4200 The commands @code{.macro} and @code{.endm} allow you to define macros that
4201 generate assembly output. For example, this definition specifies a macro
4202 @code{sum} that puts a sequence of numbers into memory:
4205 .macro sum from=0, to=5
4214 With that definition, @samp{SUM 0,5} is equivalent to this assembly input:
4226 @item .macro @var{macname}
4227 @itemx .macro @var{macname} @var{macargs} @dots{}
4228 @cindex @code{macro} directive
4229 Begin the definition of a macro called @var{macname}. If your macro
4230 definition requires arguments, specify their names after the macro name,
4231 separated by commas or spaces. You can supply a default value for any
4232 macro argument by following the name with @samp{=@var{deflt}}. For
4233 example, these are all valid @code{.macro} statements:
4237 Begin the definition of a macro called @code{comm}, which takes no
4240 @item .macro plus1 p, p1
4241 @itemx .macro plus1 p p1
4242 Either statement begins the definition of a macro called @code{plus1},
4243 which takes two arguments; within the macro definition, write
4244 @samp{\p} or @samp{\p1} to evaluate the arguments.
4246 @item .macro reserve_str p1=0 p2
4247 Begin the definition of a macro called @code{reserve_str}, with two
4248 arguments. The first argument has a default value, but not the second.
4249 After the definition is complete, you can call the macro either as
4250 @samp{reserve_str @var{a},@var{b}} (with @samp{\p1} evaluating to
4251 @var{a} and @samp{\p2} evaluating to @var{b}), or as @samp{reserve_str
4252 ,@var{b}} (with @samp{\p1} evaluating as the default, in this case
4253 @samp{0}, and @samp{\p2} evaluating to @var{b}).
4256 When you call a macro, you can specify the argument values either by
4257 position, or by keyword. For example, @samp{sum 9,17} is equivalent to
4258 @samp{sum to=17, from=9}.
4261 @cindex @code{endm} directive
4262 Mark the end of a macro definition.
4265 @cindex @code{exitm} directive
4266 Exit early from the current macro definition.
4268 @cindex number of macros executed
4269 @cindex macros, count executed
4271 @code{@value{AS}} maintains a counter of how many macros it has
4272 executed in this pseudo-variable; you can copy that number to your
4273 output with @samp{\@@}, but @emph{only within a macro definition}.
4276 @item LOCAL @var{name} [ , @dots{} ]
4277 @emph{Warning: @code{LOCAL} is only available if you select ``alternate
4278 macro syntax'' with @samp{-a} or @samp{--alternate}.} @xref{Alternate,,
4279 Alternate macro syntax}.
4281 Generate a string replacement for each of the @var{name} arguments, and
4282 replace any instances of @var{name} in each macro expansion. The
4283 replacement string is unique in the assembly, and different for each
4284 separate macro expansion. @code{LOCAL} allows you to write macros that
4285 define symbols, without fear of conflict between separate macro expansions.
4290 @section @code{.nolist}
4292 @cindex @code{nolist} directive
4293 @cindex listing control, turning off
4294 Control (in conjunction with the @code{.list} directive) whether or
4295 not assembly listings are generated. These two directives maintain an
4296 internal counter (which is zero initially). @code{.list} increments the
4297 counter, and @code{.nolist} decrements it. Assembly listings are
4298 generated whenever the counter is greater than zero.
4301 @section @code{.octa @var{bignums}}
4303 @c FIXME: double size emitted for "octa" on i960, others? Or warn?
4304 @cindex @code{octa} directive
4305 @cindex integer, 16-byte
4306 @cindex sixteen byte integer
4307 This directive expects zero or more bignums, separated by commas. For each
4308 bignum, it emits a 16-byte integer.
4310 The term ``octa'' comes from contexts in which a ``word'' is two bytes;
4311 hence @emph{octa}-word for 16 bytes.
4314 @section @code{.org @var{new-lc} , @var{fill}}
4316 @cindex @code{org} directive
4317 @cindex location counter, advancing
4318 @cindex advancing location counter
4319 @cindex current address, advancing
4320 Advance the location counter of the current section to
4321 @var{new-lc}. @var{new-lc} is either an absolute expression or an
4322 expression with the same section as the current subsection. That is,
4323 you can't use @code{.org} to cross sections: if @var{new-lc} has the
4324 wrong section, the @code{.org} directive is ignored. To be compatible
4325 with former assemblers, if the section of @var{new-lc} is absolute,
4326 @code{@value{AS}} issues a warning, then pretends the section of @var{new-lc}
4327 is the same as the current subsection.
4329 @code{.org} may only increase the location counter, or leave it
4330 unchanged; you cannot use @code{.org} to move the location counter
4333 @c double negative used below "not undefined" because this is a specific
4334 @c reference to "undefined" (as SEG_UNKNOWN is called in this manual)
4335 @c section. doc@cygnus.com 18feb91
4336 Because @code{@value{AS}} tries to assemble programs in one pass, @var{new-lc}
4337 may not be undefined. If you really detest this restriction we eagerly await
4338 a chance to share your improved assembler.
4340 Beware that the origin is relative to the start of the section, not
4341 to the start of the subsection. This is compatible with other
4342 people's assemblers.
4344 When the location counter (of the current subsection) is advanced, the
4345 intervening bytes are filled with @var{fill} which should be an
4346 absolute expression. If the comma and @var{fill} are omitted,
4347 @var{fill} defaults to zero.
4350 @section @code{.p2align[wl] @var{abs-expr}, @var{abs-expr}, @var{abs-expr}}
4352 @cindex padding the location counter given a power of two
4353 @cindex @code{p2align} directive
4354 Pad the location counter (in the current subsection) to a particular
4355 storage boundary. The first expression (which must be absolute) is the
4356 number of low-order zero bits the location counter must have after
4357 advancement. For example @samp{.p2align 3} advances the location
4358 counter until it a multiple of 8. If the location counter is already a
4359 multiple of 8, no change is needed.
4361 The second expression (also absolute) gives the fill value to be stored in the
4362 padding bytes. It (and the comma) may be omitted. If it is omitted, the
4363 padding bytes are normally zero. However, on some systems, if the section is
4364 marked as containing code and the fill value is omitted, the space is filled
4365 with no-op instructions.
4367 The third expression is also absolute, and is also optional. If it is present,
4368 it is the maximum number of bytes that should be skipped by this alignment
4369 directive. If doing the alignment would require skipping more bytes than the
4370 specified maximum, then the alignment is not done at all. You can omit the
4371 fill value (the second argument) entirely by simply using two commas after the
4372 required alignment; this can be useful if you want the alignment to be filled
4373 with no-op instructions when appropriate.
4375 @cindex @code{p2alignw} directive
4376 @cindex @code{p2alignl} directive
4377 The @code{.p2alignw} and @code{.p2alignl} directives are variants of the
4378 @code{.p2align} directive. The @code{.p2alignw} directive treats the fill
4379 pattern as a two byte word value. The @code{.p2alignl} directives treats the
4380 fill pattern as a four byte longword value. For example, @code{.p2alignw
4381 2,0x368d} will align to a multiple of 4. If it skips two bytes, they will be
4382 filled in with the value 0x368d (the exact placement of the bytes depends upon
4383 the endianness of the processor). If it skips 1 or 3 bytes, the fill value is
4388 @section @code{.previous}
4390 @cindex @code{.previous} directive
4391 @cindex Section Stack
4392 This is one of the ELF section stack manipulation directives. The others are
4393 @pxref{Section}, @xref{SubSection}, @pxref{PushSection}, and
4396 This directive swaps the current section (and subsection) with most recently
4397 referenced section (and subsection) prior to this one. Multiple
4398 @code{.previous} directives in a row will flip between two sections (and their
4401 In terms of the section stack, this directive swaps the current section with
4402 the top section on the section stack.
4407 @section @code{.popsection}
4409 @cindex @code{.popsection} directive
4410 @cindex Section Stack
4411 This is one of the ELF section stack manipulation directives. The others are
4412 @pxref{Section}, @xref{SubSection}, @pxref{PushSection}, and
4415 This directive replaces the current section (and subsection) with the top
4416 section (and subsection) on the section stack. This section is popped off the
4421 @section @code{.print @var{string}}
4423 @cindex @code{print} directive
4424 @code{@value{AS}} will print @var{string} on the standard output during
4425 assembly. You must put @var{string} in double quotes.
4429 @section @code{.protected @var{names}}
4431 @cindex @code{.protected} directive
4433 This one of the ELF visibility directives. The other two are
4434 @pxref{Hidden} and @pxref{Internal}
4436 This directive overrides the named symbols default visibility (which is set by
4437 their binding: local, global or weak). The directive sets the visibility to
4438 @code{protected} which means that any references to the symbols from within the
4439 components that defines them must be resolved to the definition in that
4440 component, even if a definition in another component would normally preempt
4445 @section @code{.psize @var{lines} , @var{columns}}
4447 @cindex @code{psize} directive
4448 @cindex listing control: paper size
4449 @cindex paper size, for listings
4450 Use this directive to declare the number of lines---and, optionally, the
4451 number of columns---to use for each page, when generating listings.
4453 If you do not use @code{.psize}, listings use a default line-count
4454 of 60. You may omit the comma and @var{columns} specification; the
4455 default width is 200 columns.
4457 @code{@value{AS}} generates formfeeds whenever the specified number of
4458 lines is exceeded (or whenever you explicitly request one, using
4461 If you specify @var{lines} as @code{0}, no formfeeds are generated save
4462 those explicitly specified with @code{.eject}.
4465 @section @code{.purgem @var{name}}
4467 @cindex @code{purgem} directive
4468 Undefine the macro @var{name}, so that later uses of the string will not be
4469 expanded. @xref{Macro}.
4473 @section @code{.pushsection @var{name} , @var{subsection}}
4475 @cindex @code{.pushsection} directive
4476 @cindex Section Stack
4477 This is one of the ELF section stack manipulation directives. The others are
4478 @pxref{Section}, @xref{SubSection}, @pxref{PopSection}, and
4481 This directive is a synonym for @code{.section}. It psuhes the current section
4482 (and subsection) onto the top of the section stack, and then replaces the
4483 current section and subsection with @code{name} and @code{subsection}.
4487 @section @code{.quad @var{bignums}}
4489 @cindex @code{quad} directive
4490 @code{.quad} expects zero or more bignums, separated by commas. For
4491 each bignum, it emits
4493 an 8-byte integer. If the bignum won't fit in 8 bytes, it prints a
4494 warning message; and just takes the lowest order 8 bytes of the bignum.
4495 @cindex eight-byte integer
4496 @cindex integer, 8-byte
4498 The term ``quad'' comes from contexts in which a ``word'' is two bytes;
4499 hence @emph{quad}-word for 8 bytes.
4502 a 16-byte integer. If the bignum won't fit in 16 bytes, it prints a
4503 warning message; and just takes the lowest order 16 bytes of the bignum.
4504 @cindex sixteen-byte integer
4505 @cindex integer, 16-byte
4509 @section @code{.rept @var{count}}
4511 @cindex @code{rept} directive
4512 Repeat the sequence of lines between the @code{.rept} directive and the next
4513 @code{.endr} directive @var{count} times.
4515 For example, assembling
4523 is equivalent to assembling
4532 @section @code{.sbttl "@var{subheading}"}
4534 @cindex @code{sbttl} directive
4535 @cindex subtitles for listings
4536 @cindex listing control: subtitle
4537 Use @var{subheading} as the title (third line, immediately after the
4538 title line) when generating assembly listings.
4540 This directive affects subsequent pages, as well as the current page if
4541 it appears within ten lines of the top of a page.
4545 @section @code{.scl @var{class}}
4547 @cindex @code{scl} directive
4548 @cindex symbol storage class (COFF)
4549 @cindex COFF symbol storage class
4550 Set the storage-class value for a symbol. This directive may only be
4551 used inside a @code{.def}/@code{.endef} pair. Storage class may flag
4552 whether a symbol is static or external, or it may record further
4553 symbolic debugging information.
4556 The @samp{.scl} directive is primarily associated with COFF output; when
4557 configured to generate @code{b.out} output format, @code{@value{AS}}
4558 accepts this directive but ignores it.
4563 @section @code{.section @var{name}} (COFF version)
4565 @cindex @code{section} directive
4566 @cindex named section
4567 Use the @code{.section} directive to assemble the following code into a section
4570 This directive is only supported for targets that actually support arbitrarily
4571 named sections; on @code{a.out} targets, for example, it is not accepted, even
4572 with a standard @code{a.out} section name.
4574 For COFF targets, the @code{.section} directive is used in one of the following
4578 .section @var{name}[, "@var{flags}"]
4579 .section @var{name}[, @var{subsegment}]
4582 If the optional argument is quoted, it is taken as flags to use for the
4583 section. Each flag is a single character. The following flags are recognized:
4586 bss section (uninitialized data)
4588 section is not loaded
4598 shared section (meaningful for PE targets)
4601 If no flags are specified, the default flags depend upon the section name. If
4602 the section name is not recognized, the default will be for the section to be
4603 loaded and writable.
4605 If the optional argument to the @code{.section} directive is not quoted, it is
4606 taken as a subsegment number (@pxref{Sub-Sections}).
4609 @section @code{.section @var{name}} (ELF version)
4611 @cindex @code{section} directive
4612 @cindex named section
4614 @cindex Section Stack
4615 This is one of the ELF section stack manipulation directives. The others are
4616 @xref{SubSection}, @pxref{PushSection}@pxref{PopSection}, and
4620 For ELF targets, the @code{.section} directive is used like this:
4623 .section @var{name} [, "@var{flags}"[, @@@var{type}]]
4626 The optional @var{flags} argument is a quoted string which may contain any
4627 combintion of the following characters:
4630 section is allocatable
4634 section is executable
4637 The optional @var{type} argument may contain one of the following constants:
4640 section contains data
4642 section does not contain data (i.e., section only occupies space)
4645 If no flags are specified, the default flags depend upon the section name. If
4646 the section name is not recognized, the default will be for the section to have
4647 none of the above flags: it will not be allocated in memory, nor writable, nor
4648 executable. The section will contain data.
4650 For ELF targets, the assembler supports another type of @code{.section}
4651 directive for compatibility with the Solaris assembler:
4654 .section "@var{name}"[, @var{flags}...]
4657 Note that the section name is quoted. There may be a sequence of comma
4661 section is allocatable
4665 section is executable
4668 This directive replaces the current section and subsection. The replaced
4669 section and subsection are pushed onto the section stack. See the contents of
4670 the gas testsuite directory @code{gas/testsuite/gas/elf} for some examples of
4671 how this directive and the other section stack directives work.
4674 @section @code{.set @var{symbol}, @var{expression}}
4676 @cindex @code{set} directive
4677 @cindex symbol value, setting
4678 Set the value of @var{symbol} to @var{expression}. This
4679 changes @var{symbol}'s value and type to conform to
4680 @var{expression}. If @var{symbol} was flagged as external, it remains
4681 flagged (@pxref{Symbol Attributes}).
4683 You may @code{.set} a symbol many times in the same assembly.
4685 If you @code{.set} a global symbol, the value stored in the object
4686 file is the last value stored into it.
4689 The syntax for @code{set} on the HPPA is
4690 @samp{@var{symbol} .set @var{expression}}.
4694 @section @code{.short @var{expressions}}
4696 @cindex @code{short} directive
4698 @code{.short} is normally the same as @samp{.word}.
4699 @xref{Word,,@code{.word}}.
4701 In some configurations, however, @code{.short} and @code{.word} generate
4702 numbers of different lengths; @pxref{Machine Dependencies}.
4706 @code{.short} is the same as @samp{.word}. @xref{Word,,@code{.word}}.
4709 This expects zero or more @var{expressions}, and emits
4710 a 16 bit number for each.
4715 @section @code{.single @var{flonums}}
4717 @cindex @code{single} directive
4718 @cindex floating point numbers (single)
4719 This directive assembles zero or more flonums, separated by commas. It
4720 has the same effect as @code{.float}.
4722 The exact kind of floating point numbers emitted depends on how
4723 @code{@value{AS}} is configured. @xref{Machine Dependencies}.
4727 On the @value{TARGET} family, @code{.single} emits 32-bit floating point
4728 numbers in @sc{ieee} format.
4733 @section @code{.size} (COFF version)
4735 @cindex @code{size} directive
4736 This directive is generated by compilers to include auxiliary debugging
4737 information in the symbol table. It is only permitted inside
4738 @code{.def}/@code{.endef} pairs.
4741 @samp{.size} is only meaningful when generating COFF format output; when
4742 @code{@value{AS}} is generating @code{b.out}, it accepts this directive but
4746 @section @code{.size @var{name} , @var{expression}} (ELF version)
4747 @cindex @code{size} directive
4749 This directive is used to set the size associated with a symbol @var{name}.
4750 The size in bytes is computed from @var{expression} which can make use of label
4751 arithmetic. This directive is typically used to set the size of function
4755 @section @code{.sleb128 @var{expressions}}
4757 @cindex @code{sleb128} directive
4758 @var{sleb128} stands for ``signed little endian base 128.'' This is a
4759 compact, variable length representation of numbers used by the DWARF
4760 symbolic debugging format. @xref{Uleb128,@code{.uleb128}}.
4762 @ifclear no-space-dir
4764 @section @code{.skip @var{size} , @var{fill}}
4766 @cindex @code{skip} directive
4767 @cindex filling memory
4768 This directive emits @var{size} bytes, each of value @var{fill}. Both
4769 @var{size} and @var{fill} are absolute expressions. If the comma and
4770 @var{fill} are omitted, @var{fill} is assumed to be zero. This is the same as
4774 @section @code{.space @var{size} , @var{fill}}
4776 @cindex @code{space} directive
4777 @cindex filling memory
4778 This directive emits @var{size} bytes, each of value @var{fill}. Both
4779 @var{size} and @var{fill} are absolute expressions. If the comma
4780 and @var{fill} are omitted, @var{fill} is assumed to be zero. This is the same
4785 @emph{Warning:} @code{.space} has a completely different meaning for HPPA
4786 targets; use @code{.block} as a substitute. See @cite{HP9000 Series 800
4787 Assembly Language Reference Manual} (HP 92432-90001) for the meaning of the
4788 @code{.space} directive. @xref{HPPA Directives,,HPPA Assembler Directives},
4797 @section @code{.space}
4798 @cindex @code{space} directive
4800 On the AMD 29K, this directive is ignored; it is accepted for
4801 compatibility with other AMD 29K assemblers.
4804 @emph{Warning:} In most versions of the @sc{gnu} assembler, the directive
4805 @code{.space} has the effect of @code{.block} @xref{Machine Dependencies}.
4811 @section @code{.stabd, .stabn, .stabs}
4813 @cindex symbolic debuggers, information for
4814 @cindex @code{stab@var{x}} directives
4815 There are three directives that begin @samp{.stab}.
4816 All emit symbols (@pxref{Symbols}), for use by symbolic debuggers.
4817 The symbols are not entered in the @code{@value{AS}} hash table: they
4818 cannot be referenced elsewhere in the source file.
4819 Up to five fields are required:
4823 This is the symbol's name. It may contain any character except
4824 @samp{\000}, so is more general than ordinary symbol names. Some
4825 debuggers used to code arbitrarily complex structures into symbol names
4829 An absolute expression. The symbol's type is set to the low 8 bits of
4830 this expression. Any bit pattern is permitted, but @code{@value{LD}}
4831 and debuggers choke on silly bit patterns.
4834 An absolute expression. The symbol's ``other'' attribute is set to the
4835 low 8 bits of this expression.
4838 An absolute expression. The symbol's descriptor is set to the low 16
4839 bits of this expression.
4842 An absolute expression which becomes the symbol's value.
4845 If a warning is detected while reading a @code{.stabd}, @code{.stabn},
4846 or @code{.stabs} statement, the symbol has probably already been created;
4847 you get a half-formed symbol in your object file. This is
4848 compatible with earlier assemblers!
4851 @cindex @code{stabd} directive
4852 @item .stabd @var{type} , @var{other} , @var{desc}
4854 The ``name'' of the symbol generated is not even an empty string.
4855 It is a null pointer, for compatibility. Older assemblers used a
4856 null pointer so they didn't waste space in object files with empty
4859 The symbol's value is set to the location counter,
4860 relocatably. When your program is linked, the value of this symbol
4861 is the address of the location counter when the @code{.stabd} was
4864 @cindex @code{stabn} directive
4865 @item .stabn @var{type} , @var{other} , @var{desc} , @var{value}
4866 The name of the symbol is set to the empty string @code{""}.
4868 @cindex @code{stabs} directive
4869 @item .stabs @var{string} , @var{type} , @var{other} , @var{desc} , @var{value}
4870 All five fields are specified.
4876 @section @code{.string} "@var{str}"
4878 @cindex string, copying to object file
4879 @cindex @code{string} directive
4881 Copy the characters in @var{str} to the object file. You may specify more than
4882 one string to copy, separated by commas. Unless otherwise specified for a
4883 particular machine, the assembler marks the end of each string with a 0 byte.
4884 You can use any of the escape sequences described in @ref{Strings,,Strings}.
4887 @section @code{.struct @var{expression}}
4889 @cindex @code{struct} directive
4890 Switch to the absolute section, and set the section offset to @var{expression},
4891 which must be an absolute expression. You might use this as follows:
4900 This would define the symbol @code{field1} to have the value 0, the symbol
4901 @code{field2} to have the value 4, and the symbol @code{field3} to have the
4902 value 8. Assembly would be left in the absolute section, and you would need to
4903 use a @code{.section} directive of some sort to change to some other section
4904 before further assembly.
4908 @section @code{.subsection @var{name}}
4910 @cindex @code{.subsection} directive
4911 @cindex Section Stack
4912 This is one of the ELF section stack manipulation directives. The others are
4913 @pxref{Section}, @xref{PushSection}, @pxref{PopSection}, and
4916 This directive replaces the current subsection with @code{name}. The current
4917 section is not changed. The replaced subsection is put onto the section stack
4918 in place of the then current top of stack subsection.
4923 @section @code{.symver}
4924 @cindex @code{symver} directive
4925 @cindex symbol versioning
4926 @cindex versions of symbols
4927 Use the @code{.symver} directive to bind symbols to specific version nodes
4928 within a source file. This is only supported on ELF platforms, and is
4929 typically used when assembling files to be linked into a shared library.
4930 There are cases where it may make sense to use this in objects to be bound
4931 into an application itself so as to override a versioned symbol from a
4934 For ELF targets, the @code{.symver} directive is used like this:
4936 .symver @var{name}, @var{name2@@nodename}
4938 In this case, the symbol @var{name} must exist and be defined within the file
4939 being assembled. The @code{.versym} directive effectively creates a symbol
4940 alias with the name @var{name2@@nodename}, and in fact the main reason that we
4941 just don't try and create a regular alias is that the @var{@@} character isn't
4942 permitted in symbol names. The @var{name2} part of the name is the actual name
4943 of the symbol by which it will be externally referenced. The name @var{name}
4944 itself is merely a name of convenience that is used so that it is possible to
4945 have definitions for multiple versions of a function within a single source
4946 file, and so that the compiler can unambiguously know which version of a
4947 function is being mentioned. The @var{nodename} portion of the alias should be
4948 the name of a node specified in the version script supplied to the linker when
4949 building a shared library. If you are attempting to override a versioned
4950 symbol from a shared library, then @var{nodename} should correspond to the
4951 nodename of the symbol you are trying to override.
4956 @section @code{.tag @var{structname}}
4958 @cindex COFF structure debugging
4959 @cindex structure debugging, COFF
4960 @cindex @code{tag} directive
4961 This directive is generated by compilers to include auxiliary debugging
4962 information in the symbol table. It is only permitted inside
4963 @code{.def}/@code{.endef} pairs. Tags are used to link structure
4964 definitions in the symbol table with instances of those structures.
4967 @samp{.tag} is only used when generating COFF format output; when
4968 @code{@value{AS}} is generating @code{b.out}, it accepts this directive but
4974 @section @code{.text @var{subsection}}
4976 @cindex @code{text} directive
4977 Tells @code{@value{AS}} to assemble the following statements onto the end of
4978 the text subsection numbered @var{subsection}, which is an absolute
4979 expression. If @var{subsection} is omitted, subsection number zero
4983 @section @code{.title "@var{heading}"}
4985 @cindex @code{title} directive
4986 @cindex listing control: title line
4987 Use @var{heading} as the title (second line, immediately after the
4988 source file name and pagenumber) when generating assembly listings.
4990 This directive affects subsequent pages, as well as the current page if
4991 it appears within ten lines of the top of a page.
4994 @section @code{.type @var{int}} (COFF version)
4996 @cindex COFF symbol type
4997 @cindex symbol type, COFF
4998 @cindex @code{type} directive
4999 This directive, permitted only within @code{.def}/@code{.endef} pairs,
5000 records the integer @var{int} as the type attribute of a symbol table entry.
5003 @samp{.type} is associated only with COFF format output; when
5004 @code{@value{AS}} is configured for @code{b.out} output, it accepts this
5005 directive but ignores it.
5008 @section @code{.type @var{name} , @var{type description}} (ELF version)
5010 @cindex ELF symbol type
5011 @cindex symbol type, ELF
5012 @cindex @code{type} directive
5013 This directive is used to set the type of symbol @var{name} to be either a
5014 function symbol or an ojbect symbol. There are five different syntaxes
5015 supported for the @var{type description} field, in order to provide
5016 comptability with various other assemblers. The syntaxes supported are:
5019 .type <name>,#function
5020 .type <name>,#object
5022 .type <name>,@@function
5023 .type <name>,@@object
5025 .type <name>,%function
5026 .type <name>,%object
5028 .type <name>,"function"
5029 .type <name>,"object"
5031 .type <name> STT_FUNCTION
5032 .type <name> STT_OBJECT
5036 @section @code{.uleb128 @var{expressions}}
5038 @cindex @code{uleb128} directive
5039 @var{uleb128} stands for ``unsigned little endian base 128.'' This is a
5040 compact, variable length representation of numbers used by the DWARF
5041 symbolic debugging format. @xref{Sleb128,@code{.sleb128}}.
5045 @section @code{.val @var{addr}}
5047 @cindex @code{val} directive
5048 @cindex COFF value attribute
5049 @cindex value attribute, COFF
5050 This directive, permitted only within @code{.def}/@code{.endef} pairs,
5051 records the address @var{addr} as the value attribute of a symbol table
5055 @samp{.val} is used only for COFF output; when @code{@value{AS}} is
5056 configured for @code{b.out}, it accepts this directive but ignores it.
5062 @section @code{.version "@var{string}"}
5064 @cindex @code{.version}
5065 This directive creates a @code{.note} section and places into it an ELF
5066 formatted note of type NT_VERSION. The note's name is set to @code{string}.
5071 @section @code{.vtable_entry @var{table}, @var{offset}}
5073 @cindex @code{.vtable_entry}
5074 This directive finds or creates a symbol @code{table} and creates a
5075 @code{VTABLE_ENTRY} relocation for it with an addend of @code{offset}.
5078 @section @code{.vtable_inherit @var{child}, @var{parent}}
5080 @cindex @code{.vtable_inherit}
5081 This directive finds the symbol @code{child} and finds or creates the symbol
5082 @code{parent} and then creates a @code{VTABLE_INHERIT} relocation for the
5083 parent whoes addend is the value of the child symbol. As a special case the
5084 parent name of @code{0} is treated as refering the @code{*ABS*} section.
5089 @section @code{.weak @var{names}}
5091 @cindex @code{.weak}
5092 This directive sets the weak attribute on the comma seperated list of symbol
5093 @code{names}. If the symbols do not already exist, they will be created.
5097 @section @code{.word @var{expressions}}
5099 @cindex @code{word} directive
5100 This directive expects zero or more @var{expressions}, of any section,
5101 separated by commas.
5104 For each expression, @code{@value{AS}} emits a 32-bit number.
5107 For each expression, @code{@value{AS}} emits a 16-bit number.
5112 The size of the number emitted, and its byte order,
5113 depend on what target computer the assembly is for.
5116 @c on amd29k, i960, sparc the "special treatment to support compilers" doesn't
5117 @c happen---32-bit addressability, period; no long/short jumps.
5118 @ifset DIFF-TBL-KLUGE
5119 @cindex difference tables altered
5120 @cindex altered difference tables
5122 @emph{Warning: Special Treatment to support Compilers}
5126 Machines with a 32-bit address space, but that do less than 32-bit
5127 addressing, require the following special treatment. If the machine of
5128 interest to you does 32-bit addressing (or doesn't require it;
5129 @pxref{Machine Dependencies}), you can ignore this issue.
5132 In order to assemble compiler output into something that works,
5133 @code{@value{AS}} occasionlly does strange things to @samp{.word} directives.
5134 Directives of the form @samp{.word sym1-sym2} are often emitted by
5135 compilers as part of jump tables. Therefore, when @code{@value{AS}} assembles a
5136 directive of the form @samp{.word sym1-sym2}, and the difference between
5137 @code{sym1} and @code{sym2} does not fit in 16 bits, @code{@value{AS}}
5138 creates a @dfn{secondary jump table}, immediately before the next label.
5139 This secondary jump table is preceded by a short-jump to the
5140 first byte after the secondary table. This short-jump prevents the flow
5141 of control from accidentally falling into the new table. Inside the
5142 table is a long-jump to @code{sym2}. The original @samp{.word}
5143 contains @code{sym1} minus the address of the long-jump to
5146 If there were several occurrences of @samp{.word sym1-sym2} before the
5147 secondary jump table, all of them are adjusted. If there was a
5148 @samp{.word sym3-sym4}, that also did not fit in sixteen bits, a
5149 long-jump to @code{sym4} is included in the secondary jump table,
5150 and the @code{.word} directives are adjusted to contain @code{sym3}
5151 minus the address of the long-jump to @code{sym4}; and so on, for as many
5152 entries in the original jump table as necessary.
5155 @emph{This feature may be disabled by compiling @code{@value{AS}} with the
5156 @samp{-DWORKING_DOT_WORD} option.} This feature is likely to confuse
5157 assembly language programmers.
5160 @c end DIFF-TBL-KLUGE
5163 @section Deprecated Directives
5165 @cindex deprecated directives
5166 @cindex obsolescent directives
5167 One day these directives won't work.
5168 They are included for compatibility with older assemblers.
5175 @node Machine Dependencies
5176 @chapter Machine Dependent Features
5178 @cindex machine dependencies
5179 The machine instruction sets are (almost by definition) different on
5180 each machine where @code{@value{AS}} runs. Floating point representations
5181 vary as well, and @code{@value{AS}} often supports a few additional
5182 directives or command-line options for compatibility with other
5183 assemblers on a particular platform. Finally, some versions of
5184 @code{@value{AS}} support special pseudo-instructions for branch
5187 This chapter discusses most of these differences, though it does not
5188 include details on any machine's instruction set. For details on that
5189 subject, see the hardware manufacturer's manual.
5193 * AMD29K-Dependent:: AMD 29K Dependent Features
5196 * ARC-Dependent:: ARC Dependent Features
5199 * ARM-Dependent:: ARM Dependent Features
5202 * D10V-Dependent:: D10V Dependent Features
5205 * D30V-Dependent:: D30V Dependent Features
5208 * H8/300-Dependent:: Hitachi H8/300 Dependent Features
5211 * H8/500-Dependent:: Hitachi H8/500 Dependent Features
5214 * HPPA-Dependent:: HPPA Dependent Features
5217 * ESA/390-Dependent:: IBM ESA/390 Dependent Features
5220 * i386-Dependent:: Intel 80386 Dependent Features
5223 * i860-Dependent:: Intel 80860 Dependent Features
5226 * i960-Dependent:: Intel 80960 Dependent Features
5229 * M32R-Dependent:: M32R Dependent Features
5232 * M68K-Dependent:: M680x0 Dependent Features
5235 * M68HC11-Dependent:: M68HC11 and 68HC12 Dependent Features
5238 * MIPS-Dependent:: MIPS Dependent Features
5241 * SH-Dependent:: Hitachi SH Dependent Features
5244 * PJ-Dependent:: picoJava Dependent Features
5247 * Sparc-Dependent:: SPARC Dependent Features
5250 * TIC54X-Dependent:: TI TMS320C54x Dependent Features
5253 * V850-Dependent:: V850 Dependent Features
5256 * Z8000-Dependent:: Z8000 Dependent Features
5259 * Vax-Dependent:: VAX Dependent Features
5266 @c The following major nodes are *sections* in the GENERIC version, *chapters*
5267 @c in single-cpu versions. This is mainly achieved by @lowersections. There is a
5268 @c peculiarity: to preserve cross-references, there must be a node called
5269 @c "Machine Dependencies". Hence the conditional nodenames in each
5270 @c major node below. Node defaulting in makeinfo requires adjacency of
5271 @c node and sectioning commands; hence the repetition of @chapter BLAH
5272 @c in both conditional blocks.
5278 @chapter ARC Dependent Features
5281 @node Machine Dependencies
5282 @chapter ARC Dependent Features
5287 * ARC-Opts:: Options
5288 * ARC-Float:: Floating Point
5289 * ARC-Directives:: Sparc Machine Directives
5295 @cindex options for ARC
5297 @cindex architectures, ARC
5298 @cindex ARC architectures
5299 The ARC chip family includes several successive levels (or other
5300 variants) of chip, using the same core instruction set, but including
5301 a few additional instructions at each level.
5303 By default, @code{@value{AS}} assumes the core instruction set (ARC
5304 base). The @code{.cpu} pseudo-op is intended to be used to select
5308 @cindex @code{-mbig-endian} option (ARC)
5309 @cindex @code{-mlittle-endian} option (ARC)
5310 @cindex ARC big-endian output
5311 @cindex ARC little-endian output
5312 @cindex big-endian output, ARC
5313 @cindex little-endian output, ARC
5315 @itemx -mlittle-endian
5316 Any @sc{arc} configuration of @code{@value{AS}} can select big-endian or
5317 little-endian output at run time (unlike most other @sc{gnu} development
5318 tools, which must be configured for one or the other). Use
5319 @samp{-mbig-endian} to select big-endian output, and @samp{-mlittle-endian}
5324 @section Floating Point
5326 @cindex floating point, ARC (@sc{ieee})
5327 @cindex ARC floating point (@sc{ieee})
5328 The ARC cpu family currently does not have hardware floating point
5329 support. Software floating point support is provided by @code{GCC}
5330 and uses @sc{ieee} floating-point numbers.
5332 @node ARC-Directives
5333 @section ARC Machine Directives
5335 @cindex ARC machine directives
5336 @cindex machine directives, ARC
5337 The ARC version of @code{@value{AS}} supports the following additional
5342 @cindex @code{cpu} directive, SPARC
5343 This must be followed by the desired cpu.
5344 The ARC is intended to be customizable, @code{.cpu} is used to
5345 select the desired variant [though currently there are none].
5352 @include c-a29k.texi
5361 @node Machine Dependencies
5362 @chapter Machine Dependent Features
5364 The machine instruction sets are different on each Hitachi chip family,
5365 and there are also some syntax differences among the families. This
5366 chapter describes the specific @code{@value{AS}} features for each
5370 * H8/300-Dependent:: Hitachi H8/300 Dependent Features
5371 * H8/500-Dependent:: Hitachi H8/500 Dependent Features
5372 * SH-Dependent:: Hitachi SH Dependent Features
5379 @include c-d10v.texi
5383 @include c-d30v.texi
5387 @include c-h8300.texi
5391 @include c-h8500.texi
5395 @include c-hppa.texi
5399 @include c-i370.texi
5403 @include c-i386.texi
5407 @include c-i860.texi
5411 @include c-i960.texi
5415 @include c-m32r.texi
5419 @include c-m68k.texi
5423 @include c-m68hc11.texi
5427 @include c-mips.texi
5431 @include c-ns32k.texi
5443 @include c-sparc.texi
5447 @include c-tic54x.texi
5459 @include c-v850.texi
5463 @c reverse effect of @down at top of generic Machine-Dep chapter
5467 @node Reporting Bugs
5468 @chapter Reporting Bugs
5469 @cindex bugs in assembler
5470 @cindex reporting bugs in assembler
5472 Your bug reports play an essential role in making @code{@value{AS}} reliable.
5474 Reporting a bug may help you by bringing a solution to your problem, or it may
5475 not. But in any case the principal function of a bug report is to help the
5476 entire community by making the next version of @code{@value{AS}} work better.
5477 Bug reports are your contribution to the maintenance of @code{@value{AS}}.
5479 In order for a bug report to serve its purpose, you must include the
5480 information that enables us to fix the bug.
5483 * Bug Criteria:: Have you found a bug?
5484 * Bug Reporting:: How to report bugs
5488 @section Have you found a bug?
5489 @cindex bug criteria
5491 If you are not sure whether you have found a bug, here are some guidelines:
5494 @cindex fatal signal
5495 @cindex assembler crash
5496 @cindex crash of assembler
5498 If the assembler gets a fatal signal, for any input whatever, that is a
5499 @code{@value{AS}} bug. Reliable assemblers never crash.
5501 @cindex error on valid input
5503 If @code{@value{AS}} produces an error message for valid input, that is a bug.
5505 @cindex invalid input
5507 If @code{@value{AS}} does not produce an error message for invalid input, that
5508 is a bug. However, you should note that your idea of ``invalid input'' might
5509 be our idea of ``an extension'' or ``support for traditional practice''.
5512 If you are an experienced user of assemblers, your suggestions for improvement
5513 of @code{@value{AS}} are welcome in any case.
5517 @section How to report bugs
5519 @cindex assembler bugs, reporting
5521 A number of companies and individuals offer support for @sc{gnu} products. If
5522 you obtained @code{@value{AS}} from a support organization, we recommend you
5523 contact that organization first.
5525 You can find contact information for many support companies and
5526 individuals in the file @file{etc/SERVICE} in the @sc{gnu} Emacs
5529 In any event, we also recommend that you send bug reports for @code{@value{AS}}
5530 to @samp{bug-gnu-utils@@gnu.org}.
5532 The fundamental principle of reporting bugs usefully is this:
5533 @strong{report all the facts}. If you are not sure whether to state a
5534 fact or leave it out, state it!
5536 Often people omit facts because they think they know what causes the problem
5537 and assume that some details do not matter. Thus, you might assume that the
5538 name of a symbol you use in an example does not matter. Well, probably it does
5539 not, but one cannot be sure. Perhaps the bug is a stray memory reference which
5540 happens to fetch from the location where that name is stored in memory;
5541 perhaps, if the name were different, the contents of that location would fool
5542 the assembler into doing the right thing despite the bug. Play it safe and
5543 give a specific, complete example. That is the easiest thing for you to do,
5544 and the most helpful.
5546 Keep in mind that the purpose of a bug report is to enable us to fix the bug if
5547 it is new to us. Therefore, always write your bug reports on the assumption
5548 that the bug has not been reported previously.
5550 Sometimes people give a few sketchy facts and ask, ``Does this ring a
5551 bell?'' Those bug reports are useless, and we urge everyone to
5552 @emph{refuse to respond to them} except to chide the sender to report
5555 To enable us to fix the bug, you should include all these things:
5559 The version of @code{@value{AS}}. @code{@value{AS}} announces it if you start
5560 it with the @samp{--version} argument.
5562 Without this, we will not know whether there is any point in looking for
5563 the bug in the current version of @code{@value{AS}}.
5566 Any patches you may have applied to the @code{@value{AS}} source.
5569 The type of machine you are using, and the operating system name and
5573 What compiler (and its version) was used to compile @code{@value{AS}}---e.g.
5577 The command arguments you gave the assembler to assemble your example and
5578 observe the bug. To guarantee you will not omit something important, list them
5579 all. A copy of the Makefile (or the output from make) is sufficient.
5581 If we were to try to guess the arguments, we would probably guess wrong
5582 and then we might not encounter the bug.
5585 A complete input file that will reproduce the bug. If the bug is observed when
5586 the assembler is invoked via a compiler, send the assembler source, not the
5587 high level language source. Most compilers will produce the assembler source
5588 when run with the @samp{-S} option. If you are using @code{@value{GCC}}, use
5589 the options @samp{-v --save-temps}; this will save the assembler source in a
5590 file with an extension of @file{.s}, and also show you exactly how
5591 @code{@value{AS}} is being run.
5594 A description of what behavior you observe that you believe is
5595 incorrect. For example, ``It gets a fatal signal.''
5597 Of course, if the bug is that @code{@value{AS}} gets a fatal signal, then we
5598 will certainly notice it. But if the bug is incorrect output, we might not
5599 notice unless it is glaringly wrong. You might as well not give us a chance to
5602 Even if the problem you experience is a fatal signal, you should still say so
5603 explicitly. Suppose something strange is going on, such as, your copy of
5604 @code{@value{AS}} is out of synch, or you have encountered a bug in the C
5605 library on your system. (This has happened!) Your copy might crash and ours
5606 would not. If you told us to expect a crash, then when ours fails to crash, we
5607 would know that the bug was not happening for us. If you had not told us to
5608 expect a crash, then we would not be able to draw any conclusion from our
5612 If you wish to suggest changes to the @code{@value{AS}} source, send us context
5613 diffs, as generated by @code{diff} with the @samp{-u}, @samp{-c}, or @samp{-p}
5614 option. Always send diffs from the old file to the new file. If you even
5615 discuss something in the @code{@value{AS}} source, refer to it by context, not
5618 The line numbers in our development sources will not match those in your
5619 sources. Your line numbers would convey no useful information to us.
5622 Here are some things that are not necessary:
5626 A description of the envelope of the bug.
5628 Often people who encounter a bug spend a lot of time investigating
5629 which changes to the input file will make the bug go away and which
5630 changes will not affect it.
5632 This is often time consuming and not very useful, because the way we
5633 will find the bug is by running a single example under the debugger
5634 with breakpoints, not by pure deduction from a series of examples.
5635 We recommend that you save your time for something else.
5637 Of course, if you can find a simpler example to report @emph{instead}
5638 of the original one, that is a convenience for us. Errors in the
5639 output will be easier to spot, running under the debugger will take
5640 less time, and so on.
5642 However, simplification is not vital; if you do not want to do this,
5643 report the bug anyway and send us the entire test case you used.
5646 A patch for the bug.
5648 A patch for the bug does help us if it is a good one. But do not omit
5649 the necessary information, such as the test case, on the assumption that
5650 a patch is all we need. We might see problems with your patch and decide
5651 to fix the problem another way, or we might not understand it at all.
5653 Sometimes with a program as complicated as @code{@value{AS}} it is very hard to
5654 construct an example that will make the program follow a certain path through
5655 the code. If you do not send us the example, we will not be able to construct
5656 one, so we will not be able to verify that the bug is fixed.
5658 And if we cannot understand what bug you are trying to fix, or why your
5659 patch should be an improvement, we will not install it. A test case will
5660 help us to understand.
5663 A guess about what the bug is or what it depends on.
5665 Such guesses are usually wrong. Even we cannot guess right about such
5666 things without first using the debugger to find the facts.
5669 @node Acknowledgements
5670 @chapter Acknowledgements
5672 If you have contributed to @code{@value{AS}} and your name isn't listed here,
5673 it is not meant as a slight. We just don't know about it. Send mail to the
5674 maintainer, and we'll correct the situation. Currently
5676 the maintainer is Ken Raeburn (email address @code{raeburn@@cygnus.com}).
5678 Dean Elsner wrote the original @sc{gnu} assembler for the VAX.@footnote{Any
5681 Jay Fenlason maintained GAS for a while, adding support for GDB-specific debug
5682 information and the 68k series machines, most of the preprocessing pass, and
5683 extensive changes in @file{messages.c}, @file{input-file.c}, @file{write.c}.
5685 K. Richard Pixley maintained GAS for a while, adding various enhancements and
5686 many bug fixes, including merging support for several processors, breaking GAS
5687 up to handle multiple object file format back ends (including heavy rewrite,
5688 testing, an integration of the coff and b.out back ends), adding configuration
5689 including heavy testing and verification of cross assemblers and file splits
5690 and renaming, converted GAS to strictly ANSI C including full prototypes, added
5691 support for m680[34]0 and cpu32, did considerable work on i960 including a COFF
5692 port (including considerable amounts of reverse engineering), a SPARC opcode
5693 file rewrite, DECstation, rs6000, and hp300hpux host ports, updated ``know''
5694 assertions and made them work, much other reorganization, cleanup, and lint.
5696 Ken Raeburn wrote the high-level BFD interface code to replace most of the code
5697 in format-specific I/O modules.
5699 The original VMS support was contributed by David L. Kashtan. Eric Youngdale
5700 has done much work with it since.
5702 The Intel 80386 machine description was written by Eliot Dresselhaus.
5704 Minh Tran-Le at IntelliCorp contributed some AIX 386 support.
5706 The Motorola 88k machine description was contributed by Devon Bowen of Buffalo
5707 University and Torbjorn Granlund of the Swedish Institute of Computer Science.
5709 Keith Knowles at the Open Software Foundation wrote the original MIPS back end
5710 (@file{tc-mips.c}, @file{tc-mips.h}), and contributed Rose format support
5711 (which hasn't been merged in yet). Ralph Campbell worked with the MIPS code to
5712 support a.out format.
5714 Support for the Zilog Z8k and Hitachi H8/300 and H8/500 processors (tc-z8k,
5715 tc-h8300, tc-h8500), and IEEE 695 object file format (obj-ieee), was written by
5716 Steve Chamberlain of Cygnus Support. Steve also modified the COFF back end to
5717 use BFD for some low-level operations, for use with the H8/300 and AMD 29k
5720 John Gilmore built the AMD 29000 support, added @code{.include} support, and
5721 simplified the configuration of which versions accept which directives. He
5722 updated the 68k machine description so that Motorola's opcodes always produced
5723 fixed-size instructions (e.g. @code{jsr}), while synthetic instructions
5724 remained shrinkable (@code{jbsr}). John fixed many bugs, including true tested
5725 cross-compilation support, and one bug in relaxation that took a week and
5726 required the proverbial one-bit fix.
5728 Ian Lance Taylor of Cygnus Support merged the Motorola and MIT syntax for the
5729 68k, completed support for some COFF targets (68k, i386 SVR3, and SCO Unix),
5730 added support for MIPS ECOFF and ELF targets, wrote the initial RS/6000 and
5731 PowerPC assembler, and made a few other minor patches.
5733 Steve Chamberlain made @code{@value{AS}} able to generate listings.
5735 Hewlett-Packard contributed support for the HP9000/300.
5737 Jeff Law wrote GAS and BFD support for the native HPPA object format (SOM)
5738 along with a fairly extensive HPPA testsuite (for both SOM and ELF object
5739 formats). This work was supported by both the Center for Software Science at
5740 the University of Utah and Cygnus Support.
5742 Support for ELF format files has been worked on by Mark Eichin of Cygnus
5743 Support (original, incomplete implementation for SPARC), Pete Hoogenboom and
5744 Jeff Law at the University of Utah (HPPA mainly), Michael Meissner of the Open
5745 Software Foundation (i386 mainly), and Ken Raeburn of Cygnus Support (sparc,
5746 and some initial 64-bit support).
5748 Linas Vepstas added GAS support for the ESA/390 "IBM 370" architecture.
5750 Richard Henderson rewrote the Alpha assembler. Klaus Kaempf wrote GAS and BFD
5751 support for openVMS/Alpha.
5753 Timothy Wall, Michael Hayes, and Greg Smart contributed to the various tic*
5756 Several engineers at Cygnus Support have also provided many small bug fixes and
5757 configuration enhancements.
5759 Many others have contributed large or small bugfixes and enhancements. If
5760 you have contributed significant work and are not mentioned on this list, and
5761 want to be, let us know. Some of the history has been lost; we are not
5762 intentionally leaving anyone out.
projects / deliverable / binutils-gdb.git / blob