This is as.info, produced by makeinfo version 4.3 from as.texinfo. START-INFO-DIR-ENTRY * As: (as). The GNU assembler. * Gas: (as). The GNU assembler. END-INFO-DIR-ENTRY This file documents the GNU Assembler "as". Copyright (C) 1991, 92, 93, 94, 95, 96, 97, 98, 99, 2000, 2001, 2002 Free Software Foundation, Inc. Permission is granted to copy, distribute and/or modify this document under the terms of the GNU Free Documentation License, Version 1.1 or any later version published by the Free Software Foundation; with no Invariant Sections, with no Front-Cover Texts, and with no Back-Cover Texts. A copy of the license is included in the section entitled "GNU Free Documentation License".  File: as.info, Node: Top, Next: Overview, Up: (dir) Using as ******** This file is a user guide to the GNU assembler `as' version 2.13. This document is distributed under the terms of the GNU Free Documentation License. A copy of the license is included in the section entitled "GNU Free Documentation License". * Menu: * Overview:: Overview * Invoking:: Command-Line Options * Syntax:: Syntax * Sections:: Sections and Relocation * Symbols:: Symbols * Expressions:: Expressions * Pseudo Ops:: Assembler Directives * Machine Dependencies:: Machine Dependent Features * Reporting Bugs:: Reporting Bugs * Acknowledgements:: Who Did What * GNU Free Documentation License:: GNU Free Documentation License * Index:: Index  File: as.info, Node: Overview, Next: Invoking, Prev: Top, Up: Top Overview ******** Here is a brief summary of how to invoke `as'. For details, *note Comand-Line Options: Invoking.. as [-a[cdhlns][=FILE]] [-D] [-defsym SYM=VAL] [-f] [-gstabs] [-gdwarf2] [-help] [-I DIR] [-J] [-K] [-L] [-listing-lhs-width=NUM] [-listing-lhs-width2=NUM] [-listing-rhs-width=NUM] [-listing-cont-lines=NUM] [-keep-locals] [-o OBJFILE] [-R] [-statistics] [-v] [-version] [-version] [-W] [-warn] [-fatal-warnings] [-w] [-x] [-Z] [-target-help] [TARGET-OPTIONS] [-|FILES ...] _Target Alpha options:_ [-mCPU] [-mdebug | -no-mdebug] [-relax] [-g] [-GSIZE] [-F] [-32addr] _Target ARC options:_ [-marc[5|6|7|8]] [-EB|-EL] _Target ARM options:_ [-mcpu=PROCESSOR[+EXTENSION...]] [-march=ARCHITECTURE[+EXTENSION...]] [-mfpu=FLOATING-POINT-FROMAT] [-mthumb] [-EB|-EL] [-mapcs-32|-mapcs-26|-mapcs-float| -mapcs-reentrant] [-mthumb-interwork] [-moabi] [-k] _Target CRIS options:_ [-underscore | -no-underscore] [-pic] [-N] [-emulation=criself | -emulation=crisaout] _Target D10V options:_ [-O] _Target D30V options:_ [-O|-n|-N] _Target i386 options:_ [-32|-64] _Target i960 options:_ [-ACA|-ACA_A|-ACB|-ACC|-AKA|-AKB| -AKC|-AMC] [-b] [-no-relax] _Target M32R options:_ [-m32rx|-[no-]warn-explicit-parallel-conflicts| -W[n]p] _Target M680X0 options:_ [-l] [-m68000|-m68010|-m68020|...] _Target M68HC11 options:_ [-m68hc11|-m68hc12] [-force-long-branchs] [-short-branchs] [-strict-direct-mode] [-print-insn-syntax] [-print-opcodes] [-generate-example] _Target MCORE options:_ [-jsri2bsr] [-sifilter] [-relax] [-mcpu=[210|340]] _Target MIPS options:_ [-nocpp] [-EL] [-EB] [-n] [-O[OPTIMIZATION LEVEL]] [-g[DEBUG LEVEL]] [-G NUM] [-KPIC] [-call_shared] [-non_shared] [-xgot] [-membedded-pic] [-mabi=ABI] [-32] [-n32] [-64] [-mfp32] [-mgp32] [-march=CPU] [-mtune=CPU] [-mips1] [-mips2] [-mips3] [-mips4] [-mips5] [-mips32] [-mips64] [-construct-floats] [-no-construct-floats] [-trap] [-no-break] [-break] [-no-trap] [-mfix7000] [-mno-fix7000] [-mips16] [-no-mips16] [-mips3d] [-no-mips3d] [-mdmx] [-no-mdmx] [-mdebug] [-no-mdebug] _Target MMIX options:_ [-fixed-special-register-names] [-globalize-symbols] [-gnu-syntax] [-relax] [-no-predefined-symbols] [-no-expand] [-no-merge-gregs] [-x] [-linker-allocated-gregs] _Target PDP11 options:_ [-mpic|-mno-pic] [-mall] [-mno-extensions] [-mEXTENSION|-mno-EXTENSION] [-mCPU] [-mMACHINE] _Target picoJava options:_ [-mb|-me] _Target PowerPC options:_ [-mpwrx|-mpwr2|-mpwr|-m601|-mppc|-mppc32|-m603|-m604| -m403|-m405|-mppc64|-m620|-mppc64bridge|-mbooke| -mbooke32|-mbooke64] [-mcom|-many|-maltivec] [-memb] [-mregnames|-mno-regnames] [-mrelocatable|-mrelocatable-lib] [-mlittle|-mlittle-endian|-mbig|-mbig-endian] [-msolaris|-mno-solaris] _Target SPARC options:_ [-Av6|-Av7|-Av8|-Asparclet|-Asparclite -Av8plus|-Av8plusa|-Av9|-Av9a] [-xarch=v8plus|-xarch=v8plusa] [-bump] [-32|-64] `-a[cdhlmns]' Turn on listings, in any of a variety of ways: `-ac' omit false conditionals `-ad' omit debugging directives `-ah' include high-level source `-al' include assembly `-am' include macro expansions `-an' omit forms processing `-as' include symbols `=file' set the name of the listing file You may combine these options; for example, use `-aln' for assembly listing without forms processing. The `=file' option, if used, must be the last one. By itself, `-a' defaults to `-ahls'. `-D' Ignored. This option is accepted for script compatibility with calls to other assemblers. `--defsym SYM=VALUE' Define the symbol SYM to be VALUE before assembling the input file. VALUE must be an integer constant. As in C, a leading `0x' indicates a hexadecimal value, and a leading `0' indicates an octal value. `-f' "fast"--skip whitespace and comment preprocessing (assume source is compiler output). `--gstabs' Generate stabs debugging information for each assembler line. This may help debugging assembler code, if the debugger can handle it. `--gdwarf2' Generate DWARF2 debugging information for each assembler line. This may help debugging assembler code, if the debugger can handle it. Note - this option is only supported by some targets, not all of them. `--help' Print a summary of the command line options and exit. `--target-help' Print a summary of all target specific options and exit. `-I DIR' Add directory DIR to the search list for `.include' directives. `-J' Don't warn about signed overflow. `-K' Issue warnings when difference tables altered for long displacements. `-L' `--keep-locals' Keep (in the symbol table) local symbols. On traditional a.out systems these start with `L', but different systems have different local label prefixes. `--listing-lhs-width=NUMBER' Set the maximum width, in words, of the output data column for an assembler listing to NUMBER. `--listing-lhs-width2=NUMBER' Set the maximum width, in words, of the output data column for continuation lines in an assembler listing to NUMBER. `--listing-rhs-width=NUMBER' Set the maximum width of an input source line, as displayed in a listing, to NUMBER bytes. `--listing-cont-lines=NUMBER' Set the maximum number of lines printed in a listing for a single line of input to NUMBER + 1. `-o OBJFILE' Name the object-file output from `as' OBJFILE. `-R' Fold the data section into the text section. `--statistics' Print the maximum space (in bytes) and total time (in seconds) used by assembly. `--strip-local-absolute' Remove local absolute symbols from the outgoing symbol table. `-v' `-version' Print the `as' version. `--version' Print the `as' version and exit. `-W' `--no-warn' Suppress warning messages. `--fatal-warnings' Treat warnings as errors. `--warn' Don't suppress warning messages or treat them as errors. `-w' Ignored. `-x' Ignored. `-Z' Generate an object file even after errors. `-- | FILES ...' Standard input, or source files to assemble. The following options are available when as is configured for an ARC processor. `-marc[5|6|7|8]' This option selects the core processor variant. `-EB | -EL' Select either big-endian (-EB) or little-endian (-EL) output. The following options are available when as is configured for the ARM processor family. `-mcpu=PROCESSOR[+EXTENSION...]' Specify which ARM processor variant is the target. `-march=ARCHITECTURE[+EXTENSION...]' Specify which ARM architecture variant is used by the target. `-mfpu=FLOATING-POINT-FORMAT' Select which Floating Point architecture is the target. `-mthumb' Enable Thumb only instruction decoding. `-mapcs-32 | -mapcs-26 | -mapcs-float | -mapcs-reentrant | -moabi' Select which procedure calling convention is in use. `-EB | -EL' Select either big-endian (-EB) or little-endian (-EL) output. `-mthumb-interwork' Specify that the code has been generated with interworking between Thumb and ARM code in mind. `-k' Specify that PIC code has been generated. See the info pages for documentation of the CRIS-specific options. The following options are available when as is configured for a D10V processor. `-O' Optimize output by parallelizing instructions. The following options are available when as is configured for a D30V processor. `-O' Optimize output by parallelizing instructions. `-n' Warn when nops are generated. `-N' Warn when a nop after a 32-bit multiply instruction is generated. The following options are available when as is configured for the Intel 80960 processor. `-ACA | -ACA_A | -ACB | -ACC | -AKA | -AKB | -AKC | -AMC' Specify which variant of the 960 architecture is the target. `-b' Add code to collect statistics about branches taken. `-no-relax' Do not alter compare-and-branch instructions for long displacements; error if necessary. The following options are available when as is configured for the Mitsubishi M32R series. `--m32rx' Specify which processor in the M32R family is the target. The default is normally the M32R, but this option changes it to the M32RX. `--warn-explicit-parallel-conflicts or --Wp' Produce warning messages when questionable parallel constructs are encountered. `--no-warn-explicit-parallel-conflicts or --Wnp' Do not produce warning messages when questionable parallel constructs are encountered. The following options are available when as is configured for the Motorola 68000 series. `-l' Shorten references to undefined symbols, to one word instead of two. `-m68000 | -m68008 | -m68010 | -m68020 | -m68030' `| -m68040 | -m68060 | -m68302 | -m68331 | -m68332' `| -m68333 | -m68340 | -mcpu32 | -m5200' Specify what processor in the 68000 family is the target. The default is normally the 68020, but this can be changed at configuration time. `-m68881 | -m68882 | -mno-68881 | -mno-68882' The target machine does (or does not) have a floating-point coprocessor. The default is to assume a coprocessor for 68020, 68030, and cpu32. Although the basic 68000 is not compatible with the 68881, a combination of the two can be specified, since it's possible to do emulation of the coprocessor instructions with the main processor. `-m68851 | -mno-68851' The target machine does (or does not) have a memory-management unit coprocessor. The default is to assume an MMU for 68020 and up. For details about the PDP-11 machine dependent features options, see *Note PDP-11-Options::. `-mpic | -mno-pic' Generate position-independent (or position-dependent) code. The default is `-mpic'. `-mall' `-mall-extensions' Enable all instruction set extensions. This is the default. `-mno-extensions' Disable all instruction set extensions. `-mEXTENSION | -mno-EXTENSION' Enable (or disable) a particular instruction set extension. `-mCPU' Enable the instruction set extensions supported by a particular CPU, and disable all other extensions. `-mMACHINE' Enable the instruction set extensions supported by a particular machine model, and disable all other extensions. The following options are available when as is configured for a picoJava processor. `-mb' Generate "big endian" format output. `-ml' Generate "little endian" format output. The following options are available when as is configured for the Motorola 68HC11 or 68HC12 series. `-m68hc11 | -m68hc12' Specify what processor is the target. The default is defined by the configuration option when building the assembler. `--force-long-branchs' Relative branches are turned into absolute ones. This concerns conditional branches, unconditional branches and branches to a sub routine. `-S | --short-branchs' Do not turn relative branchs into absolute ones when the offset is out of range. `--strict-direct-mode' Do not turn the direct addressing mode into extended addressing mode when the instruction does not support direct addressing mode. `--print-insn-syntax' Print the syntax of instruction in case of error. `--print-opcodes' print the list of instructions with syntax and then exit. `--generate-example' print an example of instruction for each possible instruction and then exit. This option is only useful for testing `as'. The following options are available when `as' is configured for the SPARC architecture: `-Av6 | -Av7 | -Av8 | -Asparclet | -Asparclite' `-Av8plus | -Av8plusa | -Av9 | -Av9a' Explicitly select a variant of the SPARC architecture. `-Av8plus' and `-Av8plusa' select a 32 bit environment. `-Av9' and `-Av9a' select a 64 bit environment. `-Av8plusa' and `-Av9a' enable the SPARC V9 instruction set with UltraSPARC extensions. `-xarch=v8plus | -xarch=v8plusa' For compatibility with the Solaris v9 assembler. These options are equivalent to -Av8plus and -Av8plusa, respectively. `-bump' Warn when the assembler switches to another architecture. The following options are available when as is configured for a MIPS processor. `-G NUM' This option sets the largest size of an object that can be referenced implicitly with the `gp' register. It is only accepted for targets that use ECOFF format, such as a DECstation running Ultrix. The default value is 8. `-EB' Generate "big endian" format output. `-EL' Generate "little endian" format output. `-mips1' `-mips2' `-mips3' `-mips4' `-mips5' `-mips32' `-mips64' Generate code for a particular MIPS Instruction Set Architecture level. `-mips1' is an alias for `-march=r3000', `-mips2' is an alias for `-march=r6000', `-mips3' is an alias for `-march=r4000' and `-mips4' is an alias for `-march=r8000'. `-mips5', `-mips32', and `-mips64' correspond to generic `MIPS V', `MIPS32', and `MIPS64' ISA processors, respectively. `-march=CPU' Generate code for a particular MIPS cpu. `-mtune=CPU' Schedule and tune for a particular MIPS cpu. `-mfix7000' `-mno-fix7000' Cause nops to be inserted if the read of the destination register of an mfhi or mflo instruction occurs in the following two instructions. `-mdebug' `-no-mdebug' Cause stabs-style debugging output to go into an ECOFF-style .mdebug section instead of the standard ELF .stabs sections. `-mgp32' `-mfp32' The register sizes are normally inferred from the ISA and ABI, but these flags force a certain group of registers to be treated as 32 bits wide at all times. `-mgp32' controls the size of general-purpose registers and `-mfp32' controls the size of floating-point registers. `-mips16' `-no-mips16' Generate code for the MIPS 16 processor. This is equivalent to putting `.set mips16' at the start of the assembly file. `-no-mips16' turns off this option. `-mips3d' `-no-mips3d' Generate code for the MIPS-3D Application Specific Extension. This tells the assembler to accept MIPS-3D instructions. `-no-mips3d' turns off this option. `-mdmx' `-no-mdmx' Generate code for the MDMX Application Specific Extension. This tells the assembler to accept MDMX instructions. `-no-mdmx' turns off this option. `--construct-floats' `--no-construct-floats' The `--no-construct-floats' option disables the construction of double width floating point constants by loading the two halves of the value into the two single width floating point registers that make up the double width register. By default `--construct-floats' is selected, allowing construction of these floating point constants. `--emulation=NAME' This option causes `as' to emulate `as' configured for some other target, in all respects, including output format (choosing between ELF and ECOFF only), handling of pseudo-opcodes which may generate debugging information or store symbol table information, and default endianness. The available configuration names are: `mipsecoff', `mipself', `mipslecoff', `mipsbecoff', `mipslelf', `mipsbelf'. The first two do not alter the default endianness from that of the primary target for which the assembler was configured; the others change the default to little- or big-endian as indicated by the `b' or `l' in the name. Using `-EB' or `-EL' will override the endianness selection in any case. This option is currently supported only when the primary target `as' is configured for is a MIPS ELF or ECOFF target. Furthermore, the primary target or others specified with `--enable-targets=...' at configuration time must include support for the other format, if both are to be available. For example, the Irix 5 configuration includes support for both. Eventually, this option will support more configurations, with more fine-grained control over the assembler's behavior, and will be supported for more processors. `-nocpp' `as' ignores this option. It is accepted for compatibility with the native tools. `--trap' `--no-trap' `--break' `--no-break' Control how to deal with multiplication overflow and division by zero. `--trap' or `--no-break' (which are synonyms) take a trap exception (and only work for Instruction Set Architecture level 2 and higher); `--break' or `--no-trap' (also synonyms, and the default) take a break exception. `-n' When this option is used, `as' will issue a warning every time it generates a nop instruction from a macro. The following options are available when as is configured for an MCore processor. `-jsri2bsr' `-nojsri2bsr' Enable or disable the JSRI to BSR transformation. By default this is enabled. The command line option `-nojsri2bsr' can be used to disable it. `-sifilter' `-nosifilter' Enable or disable the silicon filter behaviour. By default this is disabled. The default can be overridden by the `-sifilter' command line option. `-relax' Alter jump instructions for long displacements. `-mcpu=[210|340]' Select the cpu type on the target hardware. This controls which instructions can be assembled. `-EB' Assemble for a big endian target. `-EL' Assemble for a little endian target. See the info pages for documentation of the MMIX-specific options. * Menu: * Manual:: Structure of this Manual * GNU Assembler:: The GNU Assembler * Object Formats:: Object File Formats * Command Line:: Command Line * Input Files:: Input Files * Object:: Output (Object) File * Errors:: Error and Warning Messages  File: as.info, Node: Manual, Next: GNU Assembler, Up: Overview Structure of this Manual ======================== This manual is intended to describe what you need to know to use GNU `as'. We cover the syntax expected in source files, including notation for symbols, constants, and expressions; the directives that `as' understands; and of course how to invoke `as'. This manual also describes some of the machine-dependent features of various flavors of the assembler. On the other hand, this manual is _not_ intended as an introduction to programming in assembly language--let alone programming in general! In a similar vein, we make no attempt to introduce the machine architecture; we do _not_ describe the instruction set, standard mnemonics, registers or addressing modes that are standard to a particular architecture. You may want to consult the manufacturer's machine architecture manual for this information.  File: as.info, Node: GNU Assembler, Next: Object Formats, Prev: Manual, Up: Overview The GNU Assembler ================= GNU `as' is really a family of assemblers. If you use (or have used) the GNU assembler on one architecture, you should find a fairly similar environment when you use it on another architecture. Each version has much in common with the others, including object file formats, most assembler directives (often called "pseudo-ops") and assembler syntax. `as' is primarily intended to assemble the output of the GNU C compiler `gcc' for use by the linker `ld'. Nevertheless, we've tried to make `as' assemble correctly everything that other assemblers for the same machine would assemble. Any exceptions are documented explicitly (*note Machine Dependencies::). This doesn't mean `as' always uses the same syntax as another assembler for the same architecture; for example, we know of several incompatible versions of 680x0 assembly language syntax. Unlike older assemblers, `as' is designed to assemble a source program in one pass of the source file. This has a subtle impact on the `.org' directive (*note `.org': Org.).  File: as.info, Node: Object Formats, Next: Command Line, Prev: GNU Assembler, Up: Overview Object File Formats =================== The GNU assembler can be configured to produce several alternative object file formats. For the most part, this does not affect how you write assembly language programs; but directives for debugging symbols are typically different in different file formats. *Note Symbol Attributes: Symbol Attributes.  File: as.info, Node: Command Line, Next: Input Files, Prev: Object Formats, Up: Overview Command Line ============ After the program name `as', the command line may contain options and file names. Options may appear in any order, and may be before, after, or between file names. The order of file names is significant. `--' (two hyphens) by itself names the standard input file explicitly, as one of the files for `as' to assemble. Except for `--' any command line argument that begins with a hyphen (`-') is an option. Each option changes the behavior of `as'. No option changes the way another option works. An option is a `-' followed by one or more letters; the case of the letter is important. All options are optional. Some options expect exactly one file name to follow them. The file name may either immediately follow the option's letter (compatible with older assemblers) or it may be the next command argument (GNU standard). These two command lines are equivalent: as -o my-object-file.o mumble.s as -omy-object-file.o mumble.s  File: as.info, Node: Input Files, Next: Object, Prev: Command Line, Up: Overview Input Files =========== We use the phrase "source program", abbreviated "source", to describe the program input to one run of `as'. The program may be in one or more files; how the source is partitioned into files doesn't change the meaning of the source. The source program is a concatenation of the text in all the files, in the order specified. Each time you run `as' it assembles exactly one source program. The source program is made up of one or more files. (The standard input is also a file.) You give `as' a command line that has zero or more input file names. The input files are read (from left file name to right). A command line argument (in any position) that has no special meaning is taken to be an input file name. If you give `as' no file names it attempts to read one input file from the `as' standard input, which is normally your terminal. You may have to type to tell `as' there is no more program to assemble. Use `--' if you need to explicitly name the standard input file in your command line. If the source is empty, `as' produces a small, empty object file. Filenames and Line-numbers -------------------------- There are two ways of locating a line in the input file (or files) and either may be used in reporting error messages. One way refers to a line number in a physical file; the other refers to a line number in a "logical" file. *Note Error and Warning Messages: Errors. "Physical files" are those files named in the command line given to `as'. "Logical files" are simply names declared explicitly by assembler directives; they bear no relation to physical files. Logical file names help error messages reflect the original source file, when `as' source is itself synthesized from other files. `as' understands the `#' directives emitted by the `gcc' preprocessor. See also *Note `.file': File.  File: as.info, Node: Object, Next: Errors, Prev: Input Files, Up: Overview Output (Object) File ==================== Every time you run `as' it produces an output file, which is your assembly language program translated into numbers. This file is the object file. Its default name is `a.out', or `b.out' when `as' is configured for the Intel 80960. You can give it another name by using the `-o' option. Conventionally, object file names end with `.o'. The default name is used for historical reasons: older assemblers were capable of assembling self-contained programs directly into a runnable program. (For some formats, this isn't currently possible, but it can be done for the `a.out' format.) The object file is meant for input to the linker `ld'. It contains assembled program code, information to help `ld' integrate the assembled program into a runnable file, and (optionally) symbolic information for the debugger.  File: as.info, Node: Errors, Prev: Object, Up: Overview Error and Warning Messages ========================== `as' may write warnings and error messages to the standard error file (usually your terminal). This should not happen when a compiler runs `as' automatically. Warnings report an assumption made so that `as' could keep assembling a flawed program; errors report a grave problem that stops the assembly. Warning messages have the format file_name:NNN:Warning Message Text (where NNN is a line number). If a logical file name has been given (*note `.file': File.) it is used for the filename, otherwise the name of the current input file is used. If a logical line number was given (*note `.line': Line.) then it is used to calculate the number printed, otherwise the actual line in the current source file is printed. The message text is intended to be self explanatory (in the grand Unix tradition). Error messages have the format file_name:NNN:FATAL:Error Message Text The file name and line number are derived as for warning messages. The actual message text may be rather less explanatory because many of them aren't supposed to happen.  File: as.info, Node: Invoking, Next: Syntax, Prev: Overview, Up: Top Command-Line Options ******************** This chapter describes command-line options available in _all_ versions of the GNU assembler; *note Machine Dependencies::, for options specific to particular machine architectures. If you are invoking `as' via the GNU C compiler (version 2), you can use the `-Wa' option to pass arguments through to the assembler. The assembler arguments must be separated from each other (and the `-Wa') by commas. For example: gcc -c -g -O -Wa,-alh,-L file.c This passes two options to the assembler: `-alh' (emit a listing to standard output with with high-level and assembly source) and `-L' (retain local symbols in the symbol table). Usually you do not need to use this `-Wa' mechanism, since many compiler command-line options are automatically passed to the assembler by the compiler. (You can call the GNU compiler driver with the `-v' option to see precisely what options it passes to each compilation pass, including the assembler.) * Menu: * a:: -a[cdhlns] enable listings * D:: -D for compatibility * f:: -f to work faster * I:: -I for .include search path * K:: -K for difference tables * L:: -L to retain local labels * listing:: --listing-XXX to configure listing output * M:: -M or --mri to assemble in MRI compatibility mode * MD:: --MD for dependency tracking * o:: -o to name the object file * R:: -R to join data and text sections * statistics:: --statistics to see statistics about assembly * traditional-format:: --traditional-format for compatible output * v:: -v to announce version * W:: -W, --no-warn, --warn, --fatal-warnings to control warnings * Z:: -Z to make object file even after errors  File: as.info, Node: a, Next: D, Up: Invoking Enable Listings: `-a[cdhlns]' ============================= These options enable listing output from the assembler. By itself, `-a' requests high-level, assembly, and symbols listing. You can use other letters to select specific options for the list: `-ah' requests a high-level language listing, `-al' requests an output-program assembly listing, and `-as' requests a symbol table listing. High-level listings require that a compiler debugging option like `-g' be used, and that assembly listings (`-al') be requested also. Use the `-ac' option to omit false conditionals from a listing. Any lines which are not assembled because of a false `.if' (or `.ifdef', or any other conditional), or a true `.if' followed by an `.else', will be omitted from the listing. Use the `-ad' option to omit debugging directives from the listing. Once you have specified one of these options, you can further control listing output and its appearance using the directives `.list', `.nolist', `.psize', `.eject', `.title', and `.sbttl'. The `-an' option turns off all forms processing. If you do not request listing output with one of the `-a' options, the listing-control directives have no effect. The letters after `-a' may be combined into one option, _e.g._, `-aln'. Note if the assembler source is coming from the standard input (eg because it is being created by `gcc' and the `-pipe' command line switch is being used) then the listing will not contain any comments or preprocessor directives. This is because the listing code buffers input source lines from stdin only after they have been preprocessed by the assembler. This reduces memory usage and makes the code more efficient.  File: as.info, Node: D, Next: f, Prev: a, Up: Invoking `-D' ==== This option has no effect whatsoever, but it is accepted to make it more likely that scripts written for other assemblers also work with `as'.  File: as.info, Node: f, Next: I, Prev: D, Up: Invoking Work Faster: `-f' ================= `-f' should only be used when assembling programs written by a (trusted) compiler. `-f' stops the assembler from doing whitespace and comment preprocessing on the input file(s) before assembling them. *Note Preprocessing: Preprocessing. _Warning:_ if you use `-f' when the files actually need to be preprocessed (if they contain comments, for example), `as' does not work correctly.  File: as.info, Node: I, Next: K, Prev: f, Up: Invoking `.include' search path: `-I' PATH ================================= Use this option to add a PATH to the list of directories `as' searches for files specified in `.include' directives (*note `.include': Include.). You may use `-I' as many times as necessary to include a variety of paths. The current working directory is always searched first; after that, `as' searches any `-I' directories in the same order as they were specified (left to right) on the command line.  File: as.info, Node: K, Next: L, Prev: I, Up: Invoking Difference Tables: `-K' ======================= `as' sometimes alters the code emitted for directives of the form `.word SYM1-SYM2'; *note `.word': Word.. You can use the `-K' option if you want a warning issued when this is done.  File: as.info, Node: L, Next: listing, Prev: K, Up: Invoking Include Local Labels: `-L' ========================== Labels beginning with `L' (upper case only) are called "local labels". *Note Symbol Names::. Normally you do not see such labels when debugging, because they are intended for the use of programs (like compilers) that compose assembler programs, not for your notice. Normally both `as' and `ld' discard such labels, so you do not normally debug with them. This option tells `as' to retain those `L...' symbols in the object file. Usually if you do this you also tell the linker `ld' to preserve symbols whose names begin with `L'. By default, a local label is any label beginning with `L', but each target is allowed to redefine the local label prefix. On the HPPA local labels begin with `L$'.  File: as.info, Node: listing, Next: M, Prev: L, Up: Invoking Configuring listing output: `--listing' ======================================= The listing feature of the assembler can be enabled via the command line switch `-a' (*note a::). This feature combines the input source file(s) with a hex dump of the corresponding locations in the output object file, and displays them as a listing file. The format of this listing can be controlled by pseudo ops inside the assembler source (*note List:: *note Title:: *note Sbttl:: *note Psize:: *note Eject::) and also by the following switches: `--listing-lhs-width=`number'' Sets the maximum width, in words, of the first line of the hex byte dump. This dump appears on the left hand side of the listing output. `--listing-lhs-width2=`number'' Sets the maximum width, in words, of any further lines of the hex byte dump for a given inut source line. If this value is not specified, it defaults to being the same as the value specified for `--listing-lhs-width'. If neither switch is used the default is to one. `--listing-rhs-width=`number'' Sets the maximum width, in characters, of the source line that is displayed alongside the hex dump. The default value for this parameter is 100. The source line is displayed on the right hand side of the listing output. `--listing-cont-lines=`number'' Sets the maximum number of continuation lines of hex dump that will be displayed for a given single line of source input. The default value is 4.  File: as.info, Node: M, Next: MD, Prev: listing, Up: Invoking Assemble in MRI Compatibility Mode: `-M' ======================================== The `-M' or `--mri' option selects MRI compatibility mode. This changes the syntax and pseudo-op handling of `as' to make it compatible with the `ASM68K' or the `ASM960' (depending upon the configured target) assembler from Microtec Research. The exact nature of the MRI syntax will not be documented here; see the MRI manuals for more information. Note in particular that the handling of macros and macro arguments is somewhat different. The purpose of this option is to permit assembling existing MRI assembler code using `as'. The MRI compatibility is not complete. Certain operations of the MRI assembler depend upon its object file format, and can not be supported using other object file formats. Supporting these would require enhancing each object file format individually. These are: * global symbols in common section The m68k MRI assembler supports common sections which are merged by the linker. Other object file formats do not support this. `as' handles common sections by treating them as a single common symbol. It permits local symbols to be defined within a common section, but it can not support global symbols, since it has no way to describe them. * complex relocations The MRI assemblers support relocations against a negated section address, and relocations which combine the start addresses of two or more sections. These are not support by other object file formats. * `END' pseudo-op specifying start address The MRI `END' pseudo-op permits the specification of a start address. This is not supported by other object file formats. The start address may instead be specified using the `-e' option to the linker, or in a linker script. * `IDNT', `.ident' and `NAME' pseudo-ops The MRI `IDNT', `.ident' and `NAME' pseudo-ops assign a module name to the output file. This is not supported by other object file formats. * `ORG' pseudo-op The m68k MRI `ORG' pseudo-op begins an absolute section at a given address. This differs from the usual `as' `.org' pseudo-op, which changes the location within the current section. Absolute sections are not supported by other object file formats. The address of a section may be assigned within a linker script. There are some other features of the MRI assembler which are not supported by `as', typically either because they are difficult or because they seem of little consequence. Some of these may be supported in future releases. * EBCDIC strings EBCDIC strings are not supported. * packed binary coded decimal Packed binary coded decimal is not supported. This means that the `DC.P' and `DCB.P' pseudo-ops are not supported. * `FEQU' pseudo-op The m68k `FEQU' pseudo-op is not supported. * `NOOBJ' pseudo-op The m68k `NOOBJ' pseudo-op is not supported. * `OPT' branch control options The m68k `OPT' branch control options--`B', `BRS', `BRB', `BRL', and `BRW'--are ignored. `as' automatically relaxes all branches, whether forward or backward, to an appropriate size, so these options serve no purpose. * `OPT' list control options The following m68k `OPT' list control options are ignored: `C', `CEX', `CL', `CRE', `E', `G', `I', `M', `MEX', `MC', `MD', `X'. * other `OPT' options The following m68k `OPT' options are ignored: `NEST', `O', `OLD', `OP', `P', `PCO', `PCR', `PCS', `R'. * `OPT' `D' option is default The m68k `OPT' `D' option is the default, unlike the MRI assembler. `OPT NOD' may be used to turn it off. * `XREF' pseudo-op. The m68k `XREF' pseudo-op is ignored. * `.debug' pseudo-op The i960 `.debug' pseudo-op is not supported. * `.extended' pseudo-op The i960 `.extended' pseudo-op is not supported. * `.list' pseudo-op. The various options of the i960 `.list' pseudo-op are not supported. * `.optimize' pseudo-op The i960 `.optimize' pseudo-op is not supported. * `.output' pseudo-op The i960 `.output' pseudo-op is not supported. * `.setreal' pseudo-op The i960 `.setreal' pseudo-op is not supported.  File: as.info, Node: MD, Next: o, Prev: M, Up: Invoking Dependency tracking: `--MD' =========================== `as' can generate a dependency file for the file it creates. This file consists of a single rule suitable for `make' describing the dependencies of the main source file. The rule is written to the file named in its argument. This feature is used in the automatic updating of makefiles.  File: as.info, Node: o, Next: R, Prev: MD, Up: Invoking Name the Object File: `-o' ========================== There is always one object file output when you run `as'. By default it has the name `a.out' (or `b.out', for Intel 960 targets only). You use this option (which takes exactly one filename) to give the object file a different name. Whatever the object file is called, `as' overwrites any existing file of the same name.  File: as.info, Node: R, Next: statistics, Prev: o, Up: Invoking Join Data and Text Sections: `-R' ================================= `-R' tells `as' to write the object file as if all data-section data lives in the text section. This is only done at the very last moment: your binary data are the same, but data section parts are relocated differently. The data section part of your object file is zero bytes long because all its bytes are appended to the text section. (*Note Sections and Relocation: Sections.) When you specify `-R' it would be possible to generate shorter address displacements (because we do not have to cross between text and data section). We refrain from doing this simply for compatibility with older versions of `as'. In future, `-R' may work this way. When `as' is configured for COFF output, this option is only useful if you use sections named `.text' and `.data'. `-R' is not supported for any of the HPPA targets. Using `-R' generates a warning from `as'.  File: as.info, Node: statistics, Next: traditional-format, Prev: R, Up: Invoking Display Assembly Statistics: `--statistics' =========================================== Use `--statistics' to display two statistics about the resources used by `as': the maximum amount of space allocated during the assembly (in bytes), and the total execution time taken for the assembly (in CPU seconds).  File: as.info, Node: traditional-format, Next: v, Prev: statistics, Up: Invoking Compatible output: `--traditional-format' ========================================= For some targets, the output of `as' is different in some ways from the output of some existing assembler. This switch requests `as' to use the traditional format instead. For example, it disables the exception frame optimizations which `as' normally does by default on `gcc' output.  File: as.info, Node: v, Next: W, Prev: traditional-format, Up: Invoking Announce Version: `-v' ====================== You can find out what version of as is running by including the option `-v' (which you can also spell as `-version') on the command line.  File: as.info, Node: W, Next: Z, Prev: v, Up: Invoking Control Warnings: `-W', `--warn', `--no-warn', `--fatal-warnings' ================================================================= `as' should never give a warning or error message when assembling compiler output. But programs written by people often cause `as' to give a warning that a particular assumption was made. All such warnings are directed to the standard error file. If you use the `-W' and `--no-warn' options, no warnings are issued. This only affects the warning messages: it does not change any particular of how `as' assembles your file. Errors, which stop the assembly, are still reported. If you use the `--fatal-warnings' option, `as' considers files that generate warnings to be in error. You can switch these options off again by specifying `--warn', which causes warnings to be output as usual.  File: as.info, Node: Z, Prev: W, Up: Invoking Generate Object File in Spite of Errors: `-Z' ============================================= After an error message, `as' normally produces no output. If for some reason you are interested in object file output even after `as' gives an error message on your program, use the `-Z' option. If there are any errors, `as' continues anyways, and writes an object file after a final warning message of the form `N errors, M warnings, generating bad object file.'  File: as.info, Node: Syntax, Next: Sections, Prev: Invoking, Up: Top Syntax ****** This chapter describes the machine-independent syntax allowed in a source file. `as' syntax is similar to what many other assemblers use; it is inspired by the BSD 4.2 assembler, except that `as' does not assemble Vax bit-fields. * Menu: * Preprocessing:: Preprocessing * Whitespace:: Whitespace * Comments:: Comments * Symbol Intro:: Symbols * Statements:: Statements * Constants:: Constants  File: as.info, Node: Preprocessing, Next: Whitespace, Up: Syntax Preprocessing ============= The `as' internal preprocessor: * adjusts and removes extra whitespace. It leaves one space or tab before the keywords on a line, and turns any other whitespace on the line into a single space. * removes all comments, replacing them with a single space, or an appropriate number of newlines. * converts character constants into the appropriate numeric values. It does not do macro processing, include file handling, or anything else you may get from your C compiler's preprocessor. You can do include file processing with the `.include' directive (*note `.include': Include.). You can use the GNU C compiler driver to get other "CPP" style preprocessing, by giving the input file a `.S' suffix. *Note Options Controlling the Kind of Output: (gcc.info)Overall Options. Excess whitespace, comments, and character constants cannot be used in the portions of the input text that are not preprocessed. If the first line of an input file is `#NO_APP' or if you use the `-f' option, whitespace and comments are not removed from the input file. Within an input file, you can ask for whitespace and comment removal in specific portions of the by putting a line that says `#APP' before the text that may contain whitespace or comments, and putting a line that says `#NO_APP' after this text. This feature is mainly intend to support `asm' statements in compilers whose output is otherwise free of comments and whitespace.  File: as.info, Node: Whitespace, Next: Comments, Prev: Preprocessing, Up: Syntax Whitespace ========== "Whitespace" is one or more blanks or tabs, in any order. Whitespace is used to separate symbols, and to make programs neater for people to read. Unless within character constants (*note Character Constants: Characters.), any whitespace means the same as exactly one space.  File: as.info, Node: Comments, Next: Symbol Intro, Prev: Whitespace, Up: Syntax Comments ======== There are two ways of rendering comments to `as'. In both cases the comment is equivalent to one space. Anything from `/*' through the next `*/' is a comment. This means you may not nest these comments. /* The only way to include a newline ('\n') in a comment is to use this sort of comment. */ /* This sort of comment does not nest. */ Anything from the "line comment" character to the next newline is considered a comment and is ignored. The line comment character is `;' for the AMD 29K family; `;' on the ARC; `@' on the ARM; `;' for the H8/300 family; `!' for the H8/500 family; `;' for the HPPA; `#' on the i386 and x86-64; `#' on the i960; `;' for the PDP-11; `;' for picoJava; `;' for Motorola PowerPC; `!' for the Hitachi SH; `!' on the SPARC; `#' on the m32r; `|' on the 680x0; `#' on the 68HC11 and 68HC12; `;' on the M880x0; `#' on the Vax; `!' for the Z8000; `#' on the V850; see *Note Machine Dependencies::. On some machines there are two different line comment characters. One character only begins a comment if it is the first non-whitespace character on a line, while the other always begins a comment. The V850 assembler also supports a double dash as starting a comment that extends to the end of the line. `--'; To be compatible with past assemblers, lines that begin with `#' have a special interpretation. Following the `#' should be an absolute expression (*note Expressions::): the logical line number of the _next_ line. Then a string (*note Strings: Strings.) is allowed: if present it is a new logical file name. The rest of the line, if any, should be whitespace. If the first non-whitespace characters on the line are not numeric, the line is ignored. (Just like a comment.) # This is an ordinary comment. # 42-6 "new_file_name" # New logical file name # This is logical line # 36. This feature is deprecated, and may disappear from future versions of `as'.  File: as.info, Node: Symbol Intro, Next: Statements, Prev: Comments, Up: Syntax Symbols ======= A "symbol" is one or more characters chosen from the set of all letters (both upper and lower case), digits and the three characters `_.$'. On most machines, you can also use `$' in symbol names; exceptions are noted in *Note Machine Dependencies::. No symbol may begin with a digit. Case is significant. There is no length limit: all characters are significant. Symbols are delimited by characters not in that set, or by the beginning of a file (since the source program must end with a newline, the end of a file is not a possible symbol delimiter). *Note Symbols::.