263 lines
10 KiB
Text
263 lines
10 KiB
Text
@c Copyright (C) 1991, 1992, 1993, 1994, 1995 Free Software Foundation, Inc.
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@c This is part of the GAS manual.
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@c For copying conditions, see the file as.texinfo.
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@page
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@node HPPA-Dependent
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@chapter HPPA Dependent Features
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@cindex support
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@menu
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* HPPA Notes:: Notes
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* HPPA Options:: Options
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* HPPA Syntax:: Syntax
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* HPPA Floating Point:: Floating Point
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* HPPA Directives:: HPPA Machine Directives
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* HPPA Opcodes:: Opcodes
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@end menu
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@node HPPA Notes
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@section Notes
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As a back end for @sc{gnu} @sc{cc} @code{@value{AS}} has been throughly tested and should
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work extremely well. We have tested it only minimally on hand written assembly
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code and no one has tested it much on the assembly output from the HP
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compilers.
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The format of the debugging sections has changed since the original
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@code{@value{AS}} port (version 1.3X) was released; therefore,
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you must rebuild all HPPA objects and libraries with the new
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assembler so that you can debug the final executable.
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The HPPA @code{@value{AS}} port generates a small subset of the relocations
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available in the SOM and ELF object file formats. Additional relocation
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support will be added as it becomes necessary.
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@node HPPA Options
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@section Options
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@code{@value{AS}} has no machine-dependent command-line options for the HPPA.
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@cindex HPPA Syntax
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@node HPPA Syntax
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@section Syntax
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The assembler syntax closely follows the HPPA instruction set
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reference manual; assembler directives and general syntax closely follow the
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HPPA assembly language reference manual, with a few noteworthy differences.
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First, a colon may immediately follow a label definition. This is
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simply for compatibility with how most assembly language programmers
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write code.
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Some obscure expression parsing problems may affect hand written code which
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uses the @code{spop} instructions, or code which makes significant
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use of the @code{!} line separator.
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@code{@value{AS}} is much less forgiving about missing arguments and other
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similar oversights than the HP assembler. @code{@value{AS}} notifies you
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of missing arguments as syntax errors; this is regarded as a feature, not a
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bug.
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Finally, @code{@value{AS}} allows you to use an external symbol without
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explicitly importing the symbol. @emph{Warning:} in the future this will be
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an error for HPPA targets.
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Special characters for HPPA targets include:
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@samp{;} is the line comment character.
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@samp{!} can be used instead of a newline to separate statements.
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Since @samp{$} has no special meaning, you may use it in symbol names.
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@node HPPA Floating Point
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@section Floating Point
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@cindex floating point, HPPA (@sc{ieee})
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@cindex HPPA floating point (@sc{ieee})
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The HPPA family uses @sc{ieee} floating-point numbers.
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@node HPPA Directives
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@section HPPA Assembler Directives
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@code{@value{AS}} for the HPPA supports many additional directives for
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compatibility with the native assembler. This section describes them only
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briefly. For detailed information on HPPA-specific assembler directives, see
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@cite{HP9000 Series 800 Assembly Language Reference Manual} (HP 92432-90001).
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@cindex HPPA directives not supported
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@code{@value{AS}} does @emph{not} support the following assembler directives
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described in the HP manual:
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@example
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.endm .liston
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.enter .locct
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.leave .macro
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.listoff
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@end example
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@cindex @code{.param} on HPPA
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Beyond those implemented for compatibility, @code{@value{AS}} supports one
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additional assembler directive for the HPPA: @code{.param}. It conveys
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register argument locations for static functions. Its syntax closely follows
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the @code{.export} directive.
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@cindex HPPA-only directives
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These are the additional directives in @code{@value{AS}} for the HPPA:
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@table @code
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@item .block @var{n}
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@itemx .blockz @var{n}
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Reserve @var{n} bytes of storage, and initialize them to zero.
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@item .call
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Mark the beginning of a procedure call. Only the special case with @emph{no
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arguments} is allowed.
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@item .callinfo [ @var{param}=@var{value}, @dots{} ] [ @var{flag}, @dots{} ]
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Specify a number of parameters and flags that define the environment for a
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procedure.
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@var{param} may be any of @samp{frame} (frame size), @samp{entry_gr} (end of
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general register range), @samp{entry_fr} (end of float register range),
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@samp{entry_sr} (end of space register range).
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The values for @var{flag} are @samp{calls} or @samp{caller} (proc has
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subroutines), @samp{no_calls} (proc does not call subroutines), @samp{save_rp}
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(preserve return pointer), @samp{save_sp} (proc preserves stack pointer),
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@samp{no_unwind} (do not unwind this proc), @samp{hpux_int} (proc is interrupt
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routine).
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@item .code
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Assemble into the standard section called @samp{$TEXT$}, subsection
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@samp{$CODE$}.
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@ifset SOM
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@item .copyright "@var{string}"
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In the SOM object format, insert @var{string} into the object code, marked as a
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copyright string.
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@end ifset
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@ifset ELF
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@item .copyright "@var{string}"
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In the ELF object format, insert @var{string} into the object code, marked as a
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version string.
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@end ifset
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@item .enter
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Not yet supported; the assembler rejects programs containing this directive.
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@item .entry
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Mark the beginning of a procedure.
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@item .exit
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Mark the end of a procedure.
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@item .export @var{name} [ ,@var{typ} ] [ ,@var{param}=@var{r} ]
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Make a procedure @var{name} available to callers. @var{typ}, if present, must
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be one of @samp{absolute}, @samp{code} (ELF only, not SOM), @samp{data},
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@samp{entry}, @samp{data}, @samp{entry}, @samp{millicode}, @samp{plabel},
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@samp{pri_prog}, or @samp{sec_prog}.
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@var{param}, if present, provides either relocation information for the
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procedure arguments and result, or a privilege level. @var{param} may be
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@samp{argw@var{n}} (where @var{n} ranges from @code{0} to @code{3}, and
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indicates one of four one-word arguments); @samp{rtnval} (the procedure's
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result); or @samp{priv_lev} (privilege level). For arguments or the result,
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@var{r} specifies how to relocate, and must be one of @samp{no} (not
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relocatable), @samp{gr} (argument is in general register), @samp{fr} (in
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floating point register), or @samp{fu} (upper half of float register).
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For @samp{priv_lev}, @var{r} is an integer.
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@item .half @var{n}
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Define a two-byte integer constant @var{n}; synonym for the portable
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@code{@value{AS}} directive @code{.short}.
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@item .import @var{name} [ ,@var{typ} ]
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Converse of @code{.export}; make a procedure available to call. The arguments
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use the same conventions as the first two arguments for @code{.export}.
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@item .label @var{name}
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Define @var{name} as a label for the current assembly location.
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@item .leave
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Not yet supported; the assembler rejects programs containing this directive.
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@item .origin @var{lc}
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Advance location counter to @var{lc}. Synonym for the @code{@value{as}}
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portable directive @code{.org}.
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@item .param @var{name} [ ,@var{typ} ] [ ,@var{param}=@var{r} ]
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@c Not in HP manual; @sc{gnu} HPPA extension
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Similar to @code{.export}, but used for static procedures.
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@item .proc
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Use preceding the first statement of a procedure.
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@item .procend
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Use following the last statement of a procedure.
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@item @var{label} .reg @var{expr}
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@c ?? Not in HP manual (Jan 1988 vn)
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Synonym for @code{.equ}; define @var{label} with the absolute expression
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@var{expr} as its value.
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@item .space @var{secname} [ ,@var{params} ]
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Switch to section @var{secname}, creating a new section by that name if
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necessary. You may only use @var{params} when creating a new section, not
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when switching to an existing one. @var{secname} may identify a section by
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number rather than by name.
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If specified, the list @var{params} declares attributes of the section,
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identified by keywords. The keywords recognized are @samp{spnum=@var{exp}}
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(identify this section by the number @var{exp}, an absolute expression),
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@samp{sort=@var{exp}} (order sections according to this sort key when linking;
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@var{exp} is an absolute expression), @samp{unloadable} (section contains no
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loadable data), @samp{notdefined} (this section defined elsewhere), and
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@samp{private} (data in this section not available to other programs).
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@item .spnum @var{secnam}
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@c ?? Not in HP manual (Jan 1988)
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Allocate four bytes of storage, and initialize them with the section number of
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the section named @var{secnam}. (You can define the section number with the
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HPPA @code{.space} directive.)
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@cindex @code{string} directive on HPPA
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@item .string "@var{str}"
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Copy the characters in the string @var{str} to the object file.
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@xref{Strings,,Strings}, for information on escape sequences you can use in
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@code{@value{AS}} strings.
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@emph{Warning!} The HPPA version of @code{.string} differs from the
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usual @code{@value{AS}} definition: it does @emph{not} write a zero byte
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after copying @var{str}.
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@item .stringz "@var{str}"
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Like @code{.string}, but appends a zero byte after copying @var{str} to object
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file.
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@item .subspa @var{name} [ ,@var{params} ]
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@itemx .nsubspa @var{name} [ ,@var{params} ]
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Similar to @code{.space}, but selects a subsection @var{name} within the
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current section. You may only specify @var{params} when you create a
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subsection (in the first instance of @code{.subspa} for this @var{name}).
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If specified, the list @var{params} declares attributes of the subsection,
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identified by keywords. The keywords recognized are @samp{quad=@var{expr}}
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(``quadrant'' for this subsection), @samp{align=@var{expr}} (alignment for
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beginning of this subsection; a power of two), @samp{access=@var{expr}} (value
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for ``access rights'' field), @samp{sort=@var{expr}} (sorting order for this
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subspace in link), @samp{code_only} (subsection contains only code),
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@samp{unloadable} (subsection cannot be loaded into memory), @samp{common}
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(subsection is common block), @samp{dup_comm} (initialized data may have
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duplicate names), or @samp{zero} (subsection is all zeros, do not write in
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object file).
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@code{.nsubspa} always creates a new subspace with the given name, even
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if one with the same name already exists.
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@item .version "@var{str}"
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Write @var{str} as version identifier in object code.
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@end table
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@node HPPA Opcodes
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@section Opcodes
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For detailed information on the HPPA machine instruction set, see
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@cite{PA-RISC Architecture and Instruction Set Reference Manual}
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(HP 09740-90039).
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