source: trunk/binutils/gas/doc/as.info-3@ 3138

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: Balign,  Next: Byte,  Prev: Asciz,  Up: Pseudo Ops

`.balign[wl] ABS-EXPR, ABS-EXPR, ABS-EXPR'
==========================================

   Pad the location counter (in the current subsection) to a particular
storage boundary.  The first expression (which must be absolute) is the
alignment request in bytes.  For example `.balign 8' advances the
location counter until it is a multiple of 8.  If the location counter
is already a multiple of 8, no change is needed.

   The second expression (also absolute) gives the fill value to be
stored in the padding bytes.  It (and the comma) may be omitted.  If it
is omitted, the padding bytes are normally zero.  However, on some
systems, if the section is marked as containing code and the fill value
is omitted, the space is filled with no-op instructions.

   The third expression is also absolute, and is also optional.  If it
is present, it is the maximum number of bytes that should be skipped by
this alignment directive.  If doing the alignment would require
skipping more bytes than the specified maximum, then the alignment is
not done at all.  You can omit the fill value (the second argument)
entirely by simply using two commas after the required alignment; this
can be useful if you want the alignment to be filled with no-op
instructions when appropriate.

   The `.balignw' and `.balignl' directives are variants of the
`.balign' directive.  The `.balignw' directive treats the fill pattern
as a two byte word value.  The `.balignl' directives treats the fill
pattern as a four byte longword value.  For example, `.balignw
4,0x368d' will align to a multiple of 4.  If it skips two bytes, they
will be filled in with the value 0x368d (the exact placement of the
bytes depends upon the endianness of the processor).  If it skips 1 or
3 bytes, the fill value is undefined.


File: as.info,  Node: Byte,  Next: Comm,  Prev: Balign,  Up: Pseudo Ops

`.byte EXPRESSIONS'
===================

   `.byte' expects zero or more expressions, separated by commas.  Each
expression is assembled into the next byte.


File: as.info,  Node: Comm,  Next: Data,  Prev: Byte,  Up: Pseudo Ops

`.comm SYMBOL , LENGTH '
========================

   `.comm' declares a common symbol named SYMBOL.  When linking, a
common symbol in one object file may be merged with a defined or common
symbol of the same name in another object file.  If `ld' does not see a
definition for the symbol-just one or more common symbols-then it will
allocate LENGTH bytes of uninitialized memory.  LENGTH must be an
absolute expression.  If `ld' sees multiple common symbols with the
same name, and they do not all have the same size, it will allocate
space using the largest size.

   When using ELF, the `.comm' directive takes an optional third
argument.  This is the desired alignment of the symbol, specified as a
byte boundary (for example, an alignment of 16 means that the least
significant 4 bits of the address should be zero).  The alignment must
be an absolute expression, and it must be a power of two.  If `ld'
allocates uninitialized memory for the common symbol, it will use the
alignment when placing the symbol.  If no alignment is specified, `as'
will set the alignment to the largest power of two less than or equal
to the size of the symbol, up to a maximum of 16.

   The syntax for `.comm' differs slightly on the HPPA.  The syntax is
`SYMBOL .comm, LENGTH'; SYMBOL is optional.


File: as.info,  Node: Data,  Next: Def,  Prev: Comm,  Up: Pseudo Ops

`.data SUBSECTION'
==================

   `.data' tells `as' to assemble the following statements onto the end
of the data subsection numbered SUBSECTION (which is an absolute
expression).  If SUBSECTION is omitted, it defaults to zero.


File: as.info,  Node: Def,  Next: Desc,  Prev: Data,  Up: Pseudo Ops

`.def NAME'
===========

   Begin defining debugging information for a symbol NAME; the
definition extends until the `.endef' directive is encountered.

   This directive is only observed when `as' is configured for COFF
format output; when producing `b.out', `.def' is recognized, but
ignored.


File: as.info,  Node: Desc,  Next: Dim,  Prev: Def,  Up: Pseudo Ops

`.desc SYMBOL, ABS-EXPRESSION'
==============================

   This directive sets the descriptor of the symbol (*note Symbol
Attributes::) to the low 16 bits of an absolute expression.

   The `.desc' directive is not available when `as' is configured for
COFF output; it is only for `a.out' or `b.out' object format.  For the
sake of compatibility, `as' accepts it, but produces no output, when
configured for COFF.


File: as.info,  Node: Dim,  Next: Double,  Prev: Desc,  Up: Pseudo Ops

`.dim'
======

   This directive is generated by compilers to include auxiliary
debugging information in the symbol table.  It is only permitted inside
`.def'/`.endef' pairs.

   `.dim' is only meaningful when generating COFF format output; when
`as' is generating `b.out', it accepts this directive but ignores it.


File: as.info,  Node: Double,  Next: Eject,  Prev: Dim,  Up: Pseudo Ops

`.double FLONUMS'
=================

   `.double' expects zero or more flonums, separated by commas.  It
assembles floating point numbers.  The exact kind of floating point
numbers emitted depends on how `as' is configured.  *Note Machine
Dependencies::.


File: as.info,  Node: Eject,  Next: Else,  Prev: Double,  Up: Pseudo Ops

`.eject'
========

   Force a page break at this point, when generating assembly listings.


File: as.info,  Node: Else,  Next: Elseif,  Prev: Eject,  Up: Pseudo Ops

`.else'
=======

   `.else' is part of the `as' support for conditional assembly; *note
`.if': If..  It marks the beginning of a section of code to be
assembled if the condition for the preceding `.if' was false.


File: as.info,  Node: Elseif,  Next: End,  Prev: Else,  Up: Pseudo Ops

`.elseif'
=========

   `.elseif' is part of the `as' support for conditional assembly;
*note `.if': If..  It is shorthand for beginning a new `.if' block that
would otherwise fill the entire `.else' section.


File: as.info,  Node: End,  Next: Endef,  Prev: Elseif,  Up: Pseudo Ops

`.end'
======

   `.end' marks the end of the assembly file.  `as' does not process
anything in the file past the `.end' directive.


File: as.info,  Node: Endef,  Next: Endfunc,  Prev: End,  Up: Pseudo Ops

`.endef'
========

   This directive flags the end of a symbol definition begun with
`.def'.

   `.endef' is only meaningful when generating COFF format output; if
`as' is configured to generate `b.out', it accepts this directive but
ignores it.


File: as.info,  Node: Endfunc,  Next: Endif,  Prev: Endef,  Up: Pseudo Ops

`.endfunc'
==========

   `.endfunc' marks the end of a function specified with `.func'.


File: as.info,  Node: Endif,  Next: Equ,  Prev: Endfunc,  Up: Pseudo Ops

`.endif'
========

   `.endif' is part of the `as' support for conditional assembly; it
marks the end of a block of code that is only assembled conditionally.
*Note `.if': If.


File: as.info,  Node: Equ,  Next: Equiv,  Prev: Endif,  Up: Pseudo Ops

`.equ SYMBOL, EXPRESSION'
=========================

   This directive sets the value of SYMBOL to EXPRESSION.  It is
synonymous with `.set'; *note `.set': Set..

   The syntax for `equ' on the HPPA is `SYMBOL .equ EXPRESSION'.


File: as.info,  Node: Equiv,  Next: Err,  Prev: Equ,  Up: Pseudo Ops

`.equiv SYMBOL, EXPRESSION'
===========================

   The `.equiv' directive is like `.equ' and `.set', except that the
assembler will signal an error if SYMBOL is already defined.  Note a
symbol which has been referenced but not actually defined is considered
to be undefined.

   Except for the contents of the error message, this is roughly
equivalent to
     .ifdef SYM
     .err
     .endif
     .equ SYM,VAL


File: as.info,  Node: Err,  Next: Exitm,  Prev: Equiv,  Up: Pseudo Ops

`.err'
======

   If `as' assembles a `.err' directive, it will print an error message
and, unless the `-Z' option was used, it will not generate an object
file.  This can be used to signal error an conditionally compiled code.


File: as.info,  Node: Exitm,  Next: Extern,  Prev: Err,  Up: Pseudo Ops

`.exitm'
========

   Exit early from the current macro definition.  *Note Macro::.


File: as.info,  Node: Extern,  Next: Fail,  Prev: Exitm,  Up: Pseudo Ops

`.extern'
=========

   `.extern' is accepted in the source program--for compatibility with
other assemblers--but it is ignored.  `as' treats all undefined symbols
as external.


File: as.info,  Node: Fail,  Next: File,  Prev: Extern,  Up: Pseudo Ops

`.fail EXPRESSION'
==================

   Generates an error or a warning.  If the value of the EXPRESSION is
500 or more, `as' will print a warning message.  If the value is less
than 500, `as' will print an error message.  The message will include
the value of EXPRESSION.  This can occasionally be useful inside
complex nested macros or conditional assembly.


File: as.info,  Node: File,  Next: Fill,  Prev: Fail,  Up: Pseudo Ops

`.file STRING'
==============

   `.file' tells `as' that we are about to start a new logical file.
STRING is the new file name.  In general, the filename is recognized
whether or not it is surrounded by quotes `"'; but if you wish to
specify an empty file name, you must give the quotes-`""'.  This
statement may go away in future: it is only recognized to be compatible
with old `as' programs.  In some configurations of `as', `.file' has
already been removed to avoid conflicts with other assemblers.  *Note
Machine Dependencies::.


File: as.info,  Node: Fill,  Next: Float,  Prev: File,  Up: Pseudo Ops

`.fill REPEAT , SIZE , VALUE'
=============================

   REPEAT, SIZE and VALUE are absolute expressions.  This emits REPEAT
copies of SIZE bytes.  REPEAT may be zero or more.  SIZE may be zero or
more, but if it is more than 8, then it is deemed to have the value 8,
compatible with other people's assemblers.  The contents of each REPEAT
bytes is taken from an 8-byte number.  The highest order 4 bytes are
zero.  The lowest order 4 bytes are VALUE rendered in the byte-order of
an integer on the computer `as' is assembling for.  Each SIZE bytes in
a repetition is taken from the lowest order SIZE bytes of this number.
Again, this bizarre behavior is compatible with other people's
assemblers.

   SIZE and VALUE are optional.  If the second comma and VALUE are
absent, VALUE is assumed zero.  If the first comma and following tokens
are absent, SIZE is assumed to be 1.


File: as.info,  Node: Float,  Next: Func,  Prev: Fill,  Up: Pseudo Ops

`.float FLONUMS'
================

   This directive assembles zero or more flonums, separated by commas.
It has the same effect as `.single'.  The exact kind of floating point
numbers emitted depends on how `as' is configured.  *Note Machine
Dependencies::.


File: as.info,  Node: Func,  Next: Global,  Prev: Float,  Up: Pseudo Ops

`.func NAME[,LABEL]'
====================

   `.func' emits debugging information to denote function NAME, and is
ignored unless the file is assembled with debugging enabled.  Only
`--gstabs' is currently supported.  LABEL is the entry point of the
function and if omitted NAME prepended with the `leading char' is used.
`leading char' is usually `_' or nothing, depending on the target.  All
functions are currently defined to have `void' return type.  The
function must be terminated with `.endfunc'.


File: as.info,  Node: Global,  Next: Hidden,  Prev: Func,  Up: Pseudo Ops

`.global SYMBOL', `.globl SYMBOL'
=================================

   `.global' makes the symbol visible to `ld'.  If you define SYMBOL in
your partial program, its value is made available to other partial
programs that are linked with it.  Otherwise, SYMBOL takes its
attributes from a symbol of the same name from another file linked into
the same program.

   Both spellings (`.globl' and `.global') are accepted, for
compatibility with other assemblers.

   On the HPPA, `.global' is not always enough to make it accessible to
other partial programs.  You may need the HPPA-only `.EXPORT' directive
as well.  *Note HPPA Assembler Directives: HPPA Directives.


File: as.info,  Node: Hidden,  Next: hword,  Prev: Global,  Up: Pseudo Ops

`.hidden NAMES'
===============

   This one of the ELF visibility directives.  The other two are
`.internal' (*note `.internal': Internal.) and `.protected' (*note
`.protected': Protected.).

   This directive overrides the named symbols default visibility (which
is set by their binding: local, global or weak).  The directive sets
the visibility to `hidden' which means that the symbols are not visible
to other components.  Such symbols are always considered to be
`protected' as well.


File: as.info,  Node: hword,  Next: Ident,  Prev: Hidden,  Up: Pseudo Ops

`.hword EXPRESSIONS'
====================

   This expects zero or more EXPRESSIONS, and emits a 16 bit number for
each.

   This directive is a synonym for `.short'; depending on the target
architecture, it may also be a synonym for `.word'.


File: as.info,  Node: Ident,  Next: If,  Prev: hword,  Up: Pseudo Ops

`.ident'
========

   This directive is used by some assemblers to place tags in object
files.  `as' simply accepts the directive for source-file compatibility
with such assemblers, but does not actually emit anything for it.


File: as.info,  Node: If,  Next: Incbin,  Prev: Ident,  Up: Pseudo Ops

`.if ABSOLUTE EXPRESSION'
=========================

   `.if' marks the beginning of a section of code which is only
considered part of the source program being assembled if the argument
(which must be an ABSOLUTE EXPRESSION) is non-zero.  The end of the
conditional section of code must be marked by `.endif' (*note `.endif':
Endif.); optionally, you may include code for the alternative
condition, flagged by `.else' (*note `.else': Else.).  If you have
several conditions to check, `.elseif' may be used to avoid nesting
blocks if/else within each subsequent `.else' block.

   The following variants of `.if' are also supported:
`.ifdef SYMBOL'
     Assembles the following section of code if the specified SYMBOL
     has been defined.  Note a symbol which has been referenced but not
     yet defined is considered to be undefined.

`.ifc STRING1,STRING2'
     Assembles the following section of code if the two strings are the
     same.  The strings may be optionally quoted with single quotes.
     If they are not quoted, the first string stops at the first comma,
     and the second string stops at the end of the line.  Strings which
     contain whitespace should be quoted.  The string comparison is
     case sensitive.

`.ifeq ABSOLUTE EXPRESSION'
     Assembles the following section of code if the argument is zero.

`.ifeqs STRING1,STRING2'
     Another form of `.ifc'.  The strings must be quoted using double
     quotes.

`.ifge ABSOLUTE EXPRESSION'
     Assembles the following section of code if the argument is greater
     than or equal to zero.

`.ifgt ABSOLUTE EXPRESSION'
     Assembles the following section of code if the argument is greater
     than zero.

`.ifle ABSOLUTE EXPRESSION'
     Assembles the following section of code if the argument is less
     than or equal to zero.

`.iflt ABSOLUTE EXPRESSION'
     Assembles the following section of code if the argument is less
     than zero.

`.ifnc STRING1,STRING2.'
     Like `.ifc', but the sense of the test is reversed: this assembles
     the following section of code if the two strings are not the same.

`.ifndef SYMBOL'
`.ifnotdef SYMBOL'
     Assembles the following section of code if the specified SYMBOL
     has not been defined.  Both spelling variants are equivalent.
     Note a symbol which has been referenced but not yet defined is
     considered to be undefined.

`.ifne ABSOLUTE EXPRESSION'
     Assembles the following section of code if the argument is not
     equal to zero (in other words, this is equivalent to `.if').

`.ifnes STRING1,STRING2'
     Like `.ifeqs', but the sense of the test is reversed: this
     assembles the following section of code if the two strings are not
     the same.


File: as.info,  Node: Incbin,  Next: Include,  Prev: If,  Up: Pseudo Ops

`.incbin "FILE"[,SKIP[,COUNT]]'
===============================

   The `incbin' directive includes FILE verbatim at the current
location. You can control the search paths used with the `-I'
command-line option (*note Command-Line Options: Invoking.).  Quotation
marks are required around FILE.

   The SKIP argument skips a number of bytes from the start of the
FILE.  The COUNT argument indicates the maximum number of bytes to
read.  Note that the data is not aligned in any way, so it is the user's
responsibility to make sure that proper alignment is provided both
before and after the `incbin' directive.


File: as.info,  Node: Include,  Next: Int,  Prev: Incbin,  Up: Pseudo Ops

`.include "FILE"'
=================

   This directive provides a way to include supporting files at
specified points in your source program.  The code from FILE is
assembled as if it followed the point of the `.include'; when the end
of the included file is reached, assembly of the original file
continues.  You can control the search paths used with the `-I'
command-line option (*note Command-Line Options: Invoking.).  Quotation
marks are required around FILE.


File: as.info,  Node: Int,  Next: Internal,  Prev: Include,  Up: Pseudo Ops

`.int EXPRESSIONS'
==================

   Expect zero or more EXPRESSIONS, of any section, separated by commas.
For each expression, emit a number that, at run time, is the value of
that expression.  The byte order and bit size of the number depends on
what kind of target the assembly is for.


File: as.info,  Node: Internal,  Next: Irp,  Prev: Int,  Up: Pseudo Ops

`.internal NAMES'
=================

   This one of the ELF visibility directives.  The other two are
`.hidden' (*note `.hidden': Hidden.) and `.protected' (*note
`.protected': Protected.).

   This directive overrides the named symbols default visibility (which
is set by their binding: local, global or weak).  The directive sets
the visibility to `internal' which means that the symbols are
considered to be `hidden' (i.e., not visible to other components), and
that some extra, processor specific processing must also be performed
upon the  symbols as well.


File: as.info,  Node: Irp,  Next: Irpc,  Prev: Internal,  Up: Pseudo Ops

`.irp SYMBOL,VALUES'...
=======================

   Evaluate a sequence of statements assigning different values to
SYMBOL.  The sequence of statements starts at the `.irp' directive, and
is terminated by an `.endr' directive.  For each VALUE, SYMBOL is set
to VALUE, and the sequence of statements is assembled.  If no VALUE is
listed, the sequence of statements is assembled once, with SYMBOL set
to the null string.  To refer to SYMBOL within the sequence of
statements, use \SYMBOL.

   For example, assembling

             .irp    param,1,2,3
             move    d\param,sp@-
             .endr

   is equivalent to assembling

             move    d1,sp@-
             move    d2,sp@-
             move    d3,sp@-


File: as.info,  Node: Irpc,  Next: Lcomm,  Prev: Irp,  Up: Pseudo Ops

`.irpc SYMBOL,VALUES'...
========================

   Evaluate a sequence of statements assigning different values to
SYMBOL.  The sequence of statements starts at the `.irpc' directive,
and is terminated by an `.endr' directive.  For each character in VALUE,
SYMBOL is set to the character, and the sequence of statements is
assembled.  If no VALUE is listed, the sequence of statements is
assembled once, with SYMBOL set to the null string.  To refer to SYMBOL
within the sequence of statements, use \SYMBOL.

   For example, assembling

             .irpc    param,123
             move    d\param,sp@-
             .endr

   is equivalent to assembling

             move    d1,sp@-
             move    d2,sp@-
             move    d3,sp@-


File: as.info,  Node: Lcomm,  Next: Lflags,  Prev: Irpc,  Up: Pseudo Ops

`.lcomm SYMBOL , LENGTH'
========================

   Reserve LENGTH (an absolute expression) bytes for a local common
denoted by SYMBOL.  The section and value of SYMBOL are those of the
new local common.  The addresses are allocated in the bss section, so
that at run-time the bytes start off zeroed.  SYMBOL is not declared
global (*note `.global': Global.), so is normally not visible to `ld'.

   Some targets permit a third argument to be used with `.lcomm'.  This
argument specifies the desired alignment of the symbol in the bss
section.

   The syntax for `.lcomm' differs slightly on the HPPA.  The syntax is
`SYMBOL .lcomm, LENGTH'; SYMBOL is optional.


File: as.info,  Node: Lflags,  Next: Line,  Prev: Lcomm,  Up: Pseudo Ops

`.lflags'
=========

   `as' accepts this directive, for compatibility with other
assemblers, but ignores it.


File: as.info,  Node: Line,  Next: Ln,  Prev: Lflags,  Up: Pseudo Ops

`.line LINE-NUMBER'
===================

   Change the logical line number.  LINE-NUMBER must be an absolute
expression.  The next line has that logical line number.  Therefore any
other statements on the current line (after a statement separator
character) are reported as on logical line number LINE-NUMBER - 1.  One
day `as' will no longer support this directive: it is recognized only
for compatibility with existing assembler programs.

   _Warning:_ In the AMD29K configuration of as, this command is not
available; use the synonym `.ln' in that context.

   Even though this is a directive associated with the `a.out' or
`b.out' object-code formats, `as' still recognizes it when producing
COFF output, and treats `.line' as though it were the COFF `.ln' _if_
it is found outside a `.def'/`.endef' pair.

   Inside a `.def', `.line' is, instead, one of the directives used by
compilers to generate auxiliary symbol information for debugging.


File: as.info,  Node: Linkonce,  Next: List,  Prev: Ln,  Up: Pseudo Ops

`.linkonce [TYPE]'
==================

   Mark the current section so that the linker only includes a single
copy of it.  This may be used to include the same section in several
different object files, but ensure that the linker will only include it
once in the final output file.  The `.linkonce' pseudo-op must be used
for each instance of the section.  Duplicate sections are detected
based on the section name, so it should be unique.

   This directive is only supported by a few object file formats; as of
this writing, the only object file format which supports it is the
Portable Executable format used on Windows NT.

   The TYPE argument is optional.  If specified, it must be one of the
following strings.  For example:
     .linkonce same_size
   Not all types may be supported on all object file formats.

`discard'
     Silently discard duplicate sections.  This is the default.

`one_only'
     Warn if there are duplicate sections, but still keep only one copy.

`same_size'
     Warn if any of the duplicates have different sizes.

`same_contents'
     Warn if any of the duplicates do not have exactly the same
     contents.


File: as.info,  Node: Ln,  Next: Linkonce,  Prev: Line,  Up: Pseudo Ops

`.ln LINE-NUMBER'
=================

   `.ln' is a synonym for `.line'.


File: as.info,  Node: MRI,  Next: Nolist,  Prev: Macro,  Up: Pseudo Ops

`.mri VAL'
==========

   If VAL is non-zero, this tells `as' to enter MRI mode.  If VAL is
zero, this tells `as' to exit MRI mode.  This change affects code
assembled until the next `.mri' directive, or until the end of the
file.  *Note MRI mode: M.


File: as.info,  Node: List,  Next: Long,  Prev: Linkonce,  Up: Pseudo Ops

`.list'
=======

   Control (in conjunction with the `.nolist' directive) whether or not
assembly listings are generated.  These two directives maintain an
internal counter (which is zero initially).   `.list' increments the
counter, and `.nolist' decrements it.  Assembly listings are generated
whenever the counter is greater than zero.

   By default, listings are disabled.  When you enable them (with the
`-a' command line option; *note Command-Line Options: Invoking.), the
initial value of the listing counter is one.


File: as.info,  Node: Long,  Next: Macro,  Prev: List,  Up: Pseudo Ops

`.long EXPRESSIONS'
===================

   `.long' is the same as `.int', *note `.int': Int..


File: as.info,  Node: Macro,  Next: MRI,  Prev: Long,  Up: Pseudo Ops

`.macro'
========

   The commands `.macro' and `.endm' allow you to define macros that
generate assembly output.  For example, this definition specifies a
macro `sum' that puts a sequence of numbers into memory:

             .macro  sum from=0, to=5
             .long   \from
             .if     \to-\from
             sum     "(\from+1)",\to
             .endif
             .endm

With that definition, `SUM 0,5' is equivalent to this assembly input:

             .long   0
             .long   1
             .long   2
             .long   3
             .long   4
             .long   5

`.macro MACNAME'
`.macro MACNAME MACARGS ...'
     Begin the definition of a macro called MACNAME.  If your macro
     definition requires arguments, specify their names after the macro
     name, separated by commas or spaces.  You can supply a default
     value for any macro argument by following the name with `=DEFLT'.
     For example, these are all valid `.macro' statements:

    `.macro comm'
          Begin the definition of a macro called `comm', which takes no
          arguments.

    `.macro plus1 p, p1'
    `.macro plus1 p p1'
          Either statement begins the definition of a macro called
          `plus1', which takes two arguments; within the macro
          definition, write `\p' or `\p1' to evaluate the arguments.

    `.macro reserve_str p1=0 p2'
          Begin the definition of a macro called `reserve_str', with two
          arguments.  The first argument has a default value, but not
          the second.  After the definition is complete, you can call
          the macro either as `reserve_str A,B' (with `\p1' evaluating
          to A and `\p2' evaluating to B), or as `reserve_str ,B' (with
          `\p1' evaluating as the default, in this case `0', and `\p2'
          evaluating to B).

     When you call a macro, you can specify the argument values either
     by position, or by keyword.  For example, `sum 9,17' is equivalent
     to `sum to=17, from=9'.

`.endm'
     Mark the end of a macro definition.

`.exitm'
     Exit early from the current macro definition.

`\@'
     `as' maintains a counter of how many macros it has executed in
     this pseudo-variable; you can copy that number to your output with
     `\@', but _only within a macro definition_.


File: as.info,  Node: Nolist,  Next: Octa,  Prev: MRI,  Up: Pseudo Ops

`.nolist'
=========

   Control (in conjunction with the `.list' directive) whether or not
assembly listings are generated.  These two directives maintain an
internal counter (which is zero initially).   `.list' increments the
counter, and `.nolist' decrements it.  Assembly listings are generated
whenever the counter is greater than zero.


File: as.info,  Node: Octa,  Next: Org,  Prev: Nolist,  Up: Pseudo Ops

`.octa BIGNUMS'
===============

   This directive expects zero or more bignums, separated by commas.
For each bignum, it emits a 16-byte integer.

   The term "octa" comes from contexts in which a "word" is two bytes;
hence _octa_-word for 16 bytes.


File: as.info,  Node: Org,  Next: P2align,  Prev: Octa,  Up: Pseudo Ops

`.org NEW-LC , FILL'
====================

   Advance the location counter of the current section to NEW-LC.
NEW-LC is either an absolute expression or an expression with the same
section as the current subsection.  That is, you can't use `.org' to
cross sections: if NEW-LC has the wrong section, the `.org' directive
is ignored.  To be compatible with former assemblers, if the section of
NEW-LC is absolute, `as' issues a warning, then pretends the section of
NEW-LC is the same as the current subsection.

   `.org' may only increase the location counter, or leave it
unchanged; you cannot use `.org' to move the location counter backwards.

   Because `as' tries to assemble programs in one pass, NEW-LC may not
be undefined.  If you really detest this restriction we eagerly await a
chance to share your improved assembler.

   Beware that the origin is relative to the start of the section, not
to the start of the subsection.  This is compatible with other people's
assemblers.

   When the location counter (of the current subsection) is advanced,
the intervening bytes are filled with FILL which should be an absolute
expression.  If the comma and FILL are omitted, FILL defaults to zero.


File: as.info,  Node: P2align,  Next: PopSection,  Prev: Org,  Up: Pseudo Ops

`.p2align[wl] ABS-EXPR, ABS-EXPR, ABS-EXPR'
===========================================

   Pad the location counter (in the current subsection) to a particular
storage boundary.  The first expression (which must be absolute) is the
number of low-order zero bits the location counter must have after
advancement.  For example `.p2align 3' advances the location counter
until it a multiple of 8.  If the location counter is already a
multiple of 8, no change is needed.

   The second expression (also absolute) gives the fill value to be
stored in the padding bytes.  It (and the comma) may be omitted.  If it
is omitted, the padding bytes are normally zero.  However, on some
systems, if the section is marked as containing code and the fill value
is omitted, the space is filled with no-op instructions.

   The third expression is also absolute, and is also optional.  If it
is present, it is the maximum number of bytes that should be skipped by
this alignment directive.  If doing the alignment would require
skipping more bytes than the specified maximum, then the alignment is
not done at all.  You can omit the fill value (the second argument)
entirely by simply using two commas after the required alignment; this
can be useful if you want the alignment to be filled with no-op
instructions when appropriate.

   The `.p2alignw' and `.p2alignl' directives are variants of the
`.p2align' directive.  The `.p2alignw' directive treats the fill
pattern as a two byte word value.  The `.p2alignl' directives treats the
fill pattern as a four byte longword value.  For example, `.p2alignw
2,0x368d' will align to a multiple of 4.  If it skips two bytes, they
will be filled in with the value 0x368d (the exact placement of the
bytes depends upon the endianness of the processor).  If it skips 1 or
3 bytes, the fill value is undefined.


File: as.info,  Node: Previous,  Next: Print,  Prev: PopSection,  Up: Pseudo Ops

`.previous'
===========

   This is one of the ELF section stack manipulation directives.  The
others are `.section' (*note Section::), `.subsection' (*note
SubSection::), `.pushsection' (*note PushSection::), and `.popsection'
(*note PopSection::).

   This directive swaps the current section (and subsection) with most
recently referenced section (and subsection) prior to this one.
Multiple `.previous' directives in a row will flip between two sections
(and their subsections).

   In terms of the section stack, this directive swaps the current
section with the top section on the section stack.


File: as.info,  Node: PopSection,  Next: Previous,  Prev: P2align,  Up: Pseudo Ops

`.popsection'
=============

   This is one of the ELF section stack manipulation directives.  The
others are `.section' (*note Section::), `.subsection' (*note
SubSection::), `.pushsection' (*note PushSection::), and `.previous'
(*note Previous::).

   This directive replaces the current section (and subsection) with
the top section (and subsection) on the section stack.  This section is
popped off the stack.


File: as.info,  Node: Print,  Next: Protected,  Prev: Previous,  Up: Pseudo Ops

`.print STRING'
===============

   `as' will print STRING on the standard output during assembly.  You
must put STRING in double quotes.


File: as.info,  Node: Protected,  Next: Psize,  Prev: Print,  Up: Pseudo Ops

`.protected NAMES'
==================

   This one of the ELF visibility directives.  The other two are
`.hidden' (*note Hidden::) and `.internal' (*note Internal::).

   This directive overrides the named symbols default visibility (which
is set by their binding: local, global or weak).  The directive sets
the visibility to `protected' which means that any references to the
symbols from within the components that defines them must be resolved
to the definition in that component, even if a definition in another
component would normally preempt this.


File: as.info,  Node: Psize,  Next: Purgem,  Prev: Protected,  Up: Pseudo Ops

`.psize LINES , COLUMNS'
========================

   Use this directive to declare the number of lines--and, optionally,
the number of columns--to use for each page, when generating listings.

   If you do not use `.psize', listings use a default line-count of 60.
You may omit the comma and COLUMNS specification; the default width is
200 columns.

   `as' generates formfeeds whenever the specified number of lines is
exceeded (or whenever you explicitly request one, using `.eject').

   If you specify LINES as `0', no formfeeds are generated save those
explicitly specified with `.eject'.


File: as.info,  Node: Purgem,  Next: PushSection,  Prev: Psize,  Up: Pseudo Ops

`.purgem NAME'
==============

   Undefine the macro NAME, so that later uses of the string will not be
expanded.  *Note Macro::.


File: as.info,  Node: PushSection,  Next: Quad,  Prev: Purgem,  Up: Pseudo Ops

`.pushsection NAME , SUBSECTION'
================================

   This is one of the ELF section stack manipulation directives.  The
others are `.section' (*note Section::), `.subsection' (*note
SubSection::), `.popsection' (*note PopSection::), and `.previous'
(*note Previous::).

   This directive is a synonym for `.section'.  It pushes the current
section (and subsection) onto the top of the section stack, and then
replaces the current section and subsection with `name' and
`subsection'.


File: as.info,  Node: Quad,  Next: Rept,  Prev: PushSection,  Up: Pseudo Ops

`.quad BIGNUMS'
===============

   `.quad' expects zero or more bignums, separated by commas.  For each
bignum, it emits an 8-byte integer.  If the bignum won't fit in 8
bytes, it prints a warning message; and just takes the lowest order 8
bytes of the bignum.

   The term "quad" comes from contexts in which a "word" is two bytes;
hence _quad_-word for 8 bytes.


File: as.info,  Node: Rept,  Next: Sbttl,  Prev: Quad,  Up: Pseudo Ops

`.rept COUNT'
=============

   Repeat the sequence of lines between the `.rept' directive and the
next `.endr' directive COUNT times.

   For example, assembling

             .rept   3
             .long   0
             .endr

   is equivalent to assembling

             .long   0
             .long   0
             .long   0


File: as.info,  Node: Sbttl,  Next: Scl,  Prev: Rept,  Up: Pseudo Ops

`.sbttl "SUBHEADING"'
=====================

   Use SUBHEADING as the title (third line, immediately after the title
line) when generating assembly listings.

   This directive affects subsequent pages, as well as the current page
if it appears within ten lines of the top of a page.


File: as.info,  Node: Scl,  Next: Section,  Prev: Sbttl,  Up: Pseudo Ops

`.scl CLASS'
============

   Set the storage-class value for a symbol.  This directive may only be
used inside a `.def'/`.endef' pair.  Storage class may flag whether a
symbol is static or external, or it may record further symbolic
debugging information.

   The `.scl' directive is primarily associated with COFF output; when
configured to generate `b.out' output format, `as' accepts this
directive but ignores it.


File: as.info,  Node: Section,  Next: Set,  Prev: Scl,  Up: Pseudo Ops

`.section NAME'
===============

   Use the `.section' directive to assemble the following code into a
section named NAME.

   This directive is only supported for targets that actually support
arbitrarily named sections; on `a.out' targets, for example, it is not
accepted, even with a standard `a.out' section name.

COFF Version
------------

   For COFF targets, the `.section' directive is used in one of the
following ways:

     .section NAME[, "FLAGS"]
     .section NAME[, SUBSEGMENT]

   If the optional argument is quoted, it is taken as flags to use for
the section.  Each flag is a single character.  The following flags are
recognized:
`b'
     bss section (uninitialized data)

`n'
     section is not loaded

`w'
     writable section

`d'
     data section

`r'
     read-only section

`x'
     executable section

`s'
     shared section (meaningful for PE targets)

`a'
     ignored.  (For compatibility with the ELF version)

   If no flags are specified, the default flags depend upon the section
name.  If the section name is not recognized, the default will be for
the section to be loaded and writable.  Note the `n' and `w' flags
remove attributes from the section, rather than adding them, so if they
are used on their own it will be as if no flags had been specified at
all.

   If the optional argument to the `.section' directive is not quoted,
it is taken as a subsegment number (*note Sub-Sections::).

ELF Version
-----------

   This is one of the ELF section stack manipulation directives.  The
others are `.subsection' (*note SubSection::), `.pushsection' (*note
PushSection::), `.popsection' (*note PopSection::), and `.previous'
(*note Previous::).

   For ELF targets, the `.section' directive is used like this:

     .section NAME [, "FLAGS"[, @TYPE[, @ENTSIZE]]]

   The optional FLAGS argument is a quoted string which may contain any
combination of the following characters:
`a'
     section is allocatable

`w'
     section is writable

`x'
     section is executable

`M'
     section is mergeable

`S'
     section contains zero terminated strings

   The optional TYPE argument may contain one of the following
constants:
`@progbits'
     section contains data

`@nobits'
     section does not contain data (i.e., section only occupies space)

   Note on targets where the `@' character is the start of a comment (eg
ARM) then another character is used instead.  For example the ARM port
uses the `%' character.

   If FLAGS contains `M' flag, TYPE argument must be specified as well
as ENTSIZE argument. Sections with `M' flag but not `S' flag must
contain fixed size constants, each ENTSIZE octets long. Sections with
both `M' and `S' must contain zero terminated strings where each
character is ENTSIZE bytes long. The linker may remove duplicates
within sections with the same name, same entity size and same flags.

   If no flags are specified, the default flags depend upon the section
name.  If the section name is not recognized, the default will be for
the section to have none of the above flags: it will not be allocated
in memory, nor writable, nor executable.  The section will contain data.

   For ELF targets, the assembler supports another type of `.section'
directive for compatibility with the Solaris assembler:

     .section "NAME"[, FLAGS...]

   Note that the section name is quoted.  There may be a sequence of
comma separated flags:
`#alloc'
     section is allocatable

`#write'
     section is writable

`#execinstr'
     section is executable

   This directive replaces the current section and subsection.  The
replaced section and subsection are pushed onto the section stack.  See
the contents of the gas testsuite directory `gas/testsuite/gas/elf' for
some examples of how this directive and the other section stack
directives work.


File: as.info,  Node: Set,  Next: Short,  Prev: Section,  Up: Pseudo Ops

`.set SYMBOL, EXPRESSION'
=========================

   Set the value of SYMBOL to EXPRESSION.  This changes SYMBOL's value
and type to conform to EXPRESSION.  If SYMBOL was flagged as external,
it remains flagged (*note Symbol Attributes::).

   You may `.set' a symbol many times in the same assembly.

   If you `.set' a global symbol, the value stored in the object file
is the last value stored into it.

   The syntax for `set' on the HPPA is `SYMBOL .set EXPRESSION'.


File: as.info,  Node: Short,  Next: Single,  Prev: Set,  Up: Pseudo Ops

`.short EXPRESSIONS'
====================

   `.short' is normally the same as `.word'.  *Note `.word': Word.

   In some configurations, however, `.short' and `.word' generate
numbers of different lengths; *note Machine Dependencies::.


File: as.info,  Node: Single,  Next: Size,  Prev: Short,  Up: Pseudo Ops

`.single FLONUMS'
=================

   This directive assembles zero or more flonums, separated by commas.
It has the same effect as `.float'.  The exact kind of floating point
numbers emitted depends on how `as' is configured.  *Note Machine
Dependencies::.


File: as.info,  Node: Size,  Next: Skip,  Prev: Single,  Up: Pseudo Ops

`.size'
=======

   This directive is used to set the size associated with a symbol.

COFF Version
------------

   For COFF targets, the `.size' directive is only permitted inside
`.def'/`.endef' pairs.  It is used like this:

     .size EXPRESSION

   `.size' is only meaningful when generating COFF format output; when
`as' is generating `b.out', it accepts this directive but ignores it.

ELF Version
-----------

   For ELF targets, the `.size' directive is used like this:

     .size NAME , EXPRESSION

   This directive sets the size associated with a symbol NAME.  The
size in bytes is computed from EXPRESSION which can make use of label
arithmetic.  This directive is typically used to set the size of
function symbols.


File: as.info,  Node: Sleb128,  Next: Space,  Prev: Skip,  Up: Pseudo Ops

`.sleb128 EXPRESSIONS'
======================

   SLEB128 stands for "signed little endian base 128."  This is a
compact, variable length representation of numbers used by the DWARF
symbolic debugging format.  *Note `.uleb128': Uleb128.


File: as.info,  Node: Skip,  Next: Sleb128,  Prev: Size,  Up: Pseudo Ops

`.skip SIZE , FILL'
===================

   This directive emits SIZE bytes, each of value FILL.  Both SIZE and
FILL are absolute expressions.  If the comma and FILL are omitted, FILL
is assumed to be zero.  This is the same as `.space'.


File: as.info,  Node: Space,  Next: Stab,  Prev: Sleb128,  Up: Pseudo Ops

`.space SIZE , FILL'
====================

   This directive emits SIZE bytes, each of value FILL.  Both SIZE and
FILL are absolute expressions.  If the comma and FILL are omitted, FILL
is assumed to be zero.  This is the same as `.skip'.

     _Warning:_ `.space' has a completely different meaning for HPPA
     targets; use `.block' as a substitute.  See `HP9000 Series 800
     Assembly Language Reference Manual' (HP 92432-90001) for the
     meaning of the `.space' directive.  *Note HPPA Assembler
     Directives: HPPA Directives, for a summary.

   On the AMD 29K, this directive is ignored; it is accepted for
compatibility with other AMD 29K assemblers.

     _Warning:_ In most versions of the GNU assembler, the directive
     `.space' has the effect of `.block'  *Note Machine Dependencies::.


File: as.info,  Node: Stab,  Next: String,  Prev: Space,  Up: Pseudo Ops

`.stabd, .stabn, .stabs'
========================

   There are three directives that begin `.stab'.  All emit symbols
(*note Symbols::), for use by symbolic debuggers.  The symbols are not
entered in the `as' hash table: they cannot be referenced elsewhere in
the source file.  Up to five fields are required:

STRING
     This is the symbol's name.  It may contain any character except
     `\000', so is more general than ordinary symbol names.  Some
     debuggers used to code arbitrarily complex structures into symbol
     names using this field.

TYPE
     An absolute expression.  The symbol's type is set to the low 8
     bits of this expression.  Any bit pattern is permitted, but `ld'
     and debuggers choke on silly bit patterns.

OTHER
     An absolute expression.  The symbol's "other" attribute is set to
     the low 8 bits of this expression.

DESC
     An absolute expression.  The symbol's descriptor is set to the low
     16 bits of this expression.

VALUE
     An absolute expression which becomes the symbol's value.

   If a warning is detected while reading a `.stabd', `.stabn', or
`.stabs' statement, the symbol has probably already been created; you
get a half-formed symbol in your object file.  This is compatible with
earlier assemblers!

`.stabd TYPE , OTHER , DESC'
     The "name" of the symbol generated is not even an empty string.
     It is a null pointer, for compatibility.  Older assemblers used a
     null pointer so they didn't waste space in object files with empty
     strings.

     The symbol's value is set to the location counter, relocatably.
     When your program is linked, the value of this symbol is the
     address of the location counter when the `.stabd' was assembled.

`.stabn TYPE , OTHER , DESC , VALUE'
     The name of the symbol is set to the empty string `""'.

`.stabs STRING ,  TYPE , OTHER , DESC , VALUE'
     All five fields are specified.


File: as.info,  Node: String,  Next: Struct,  Prev: Stab,  Up: Pseudo Ops

`.string' "STR"
===============

   Copy the characters in STR to the object file.  You may specify more
than one string to copy, separated by commas.  Unless otherwise
specified for a particular machine, the assembler marks the end of each
string with a 0 byte.  You can use any of the escape sequences
described in *Note Strings: Strings.


File: as.info,  Node: Struct,  Next: SubSection,  Prev: String,  Up: Pseudo Ops

`.struct EXPRESSION'
====================

   Switch to the absolute section, and set the section offset to
EXPRESSION, which must be an absolute expression.  You might use this
as follows:
             .struct 0
     field1:
             .struct field1 + 4
     field2:
             .struct field2 + 4
     field3:
   This would define the symbol `field1' to have the value 0, the symbol
`field2' to have the value 4, and the symbol `field3' to have the value
8.  Assembly would be left in the absolute section, and you would need
to use a `.section' directive of some sort to change to some other
section before further assembly.


File: as.info,  Node: SubSection,  Next: Symver,  Prev: Struct,  Up: Pseudo Ops

`.subsection NAME'
==================

   This is one of the ELF section stack manipulation directives.  The
others are `.section' (*note Section::), `.pushsection' (*note
PushSection::), `.popsection' (*note PopSection::), and `.previous'
(*note Previous::).

   This directive replaces the current subsection with `name'.  The
current section is not changed.  The replaced subsection is put onto
the section stack in place of the then current top of stack subsection.


File: as.info,  Node: Symver,  Next: Tag,  Prev: SubSection,  Up: Pseudo Ops

`.symver'
=========

   Use the `.symver' directive to bind symbols to specific version nodes
within a source file.  This is only supported on ELF platforms, and is
typically used when assembling files to be linked into a shared library.
There are cases where it may make sense to use this in objects to be
bound into an application itself so as to override a versioned symbol
from a shared library.

   For ELF targets, the `.symver' directive can be used like this:
     .symver NAME, NAME2@NODENAME
   If the symbol NAME is defined within the file being assembled, the
`.symver' directive effectively creates a symbol alias with the name
NAME2@NODENAME, and in fact the main reason that we just don't try and
create a regular alias is that the @ character isn't permitted in
symbol names.  The NAME2 part of the name is the actual name of the
symbol by which it will be externally referenced.  The name NAME itself
is merely a name of convenience that is used so that it is possible to
have definitions for multiple versions of a function within a single
source file, and so that the compiler can unambiguously know which
version of a function is being mentioned.  The NODENAME portion of the
alias should be the name of a node specified in the version script
supplied to the linker when building a shared library.  If you are
attempting to override a versioned symbol from a shared library, then
NODENAME should correspond to the nodename of the symbol you are trying
to override.

   If the symbol NAME is not defined within the file being assembled,
all references to NAME will be changed to NAME2@NODENAME.  If no
reference to NAME is made, NAME2@NODENAME will be removed from the
symbol table.

   Another usage of the `.symver' directive is:
     .symver NAME, NAME2@@NODENAME
   In this case, the symbol NAME must exist and be defined within the
file being assembled. It is similar to NAME2@NODENAME. The difference
is NAME2@@NODENAME will also be used to resolve references to NAME2 by
the linker.

   The third usage of the `.symver' directive is:
     .symver NAME, NAME2@@@NODENAME
   When NAME is not defined within the file being assembled, it is
treated as NAME2@NODENAME. When NAME is defined within the file being
assembled, the symbol name, NAME, will be changed to NAME2@@NODENAME.