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<title>Using as: HPPA Directives</title>
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<a name="HPPA-Directives"></a>
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<div class="header">
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<p>
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Next: <a href="HPPA-Opcodes.html#HPPA-Opcodes" accesskey="n" rel="next">HPPA Opcodes</a>, Previous: <a href="HPPA-Floating-Point.html#HPPA-Floating-Point" accesskey="p" rel="prev">HPPA Floating Point</a>, Up: <a href="HPPA_002dDependent.html#HPPA_002dDependent" accesskey="u" rel="up">HPPA-Dependent</a> [<a href="index.html#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="AS-Index.html#AS-Index" title="Index" rel="index">Index</a>]</p>
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</div>
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<hr>
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<a name="HPPA-Assembler-Directives"></a>
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<h4 class="subsection">9.13.5 HPPA Assembler Directives</h4>
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<p><code>as</code> 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</cite> (HP 92432-90001).
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</p>
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<a name="index-HPPA-directives-not-supported"></a>
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<p><code>as</code> does <em>not</em> support the following assembler directives
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described in the HP manual:
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</p>
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<div class="example">
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<pre class="example">.endm .liston
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.enter .locct
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.leave .macro
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.listoff
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</pre></div>
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<a name="index-_002eparam-on-HPPA"></a>
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<p>Beyond those implemented for compatibility, <code>as</code> supports one
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additional assembler directive for the HPPA: <code>.param</code>. It conveys
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register argument locations for static functions. Its syntax closely follows
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the <code>.export</code> directive.
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</p>
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<a name="index-HPPA_002donly-directives"></a>
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<p>These are the additional directives in <code>as</code> for the HPPA:
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</p>
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<dl compact="compact">
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<dt><code>.block <var>n</var></code></dt>
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<dt><code>.blockz <var>n</var></code></dt>
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<dd><p>Reserve <var>n</var> bytes of storage, and initialize them to zero.
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</p>
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</dd>
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<dt><code>.call</code></dt>
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<dd><p>Mark the beginning of a procedure call. Only the special case with <em>no
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arguments</em> is allowed.
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</p>
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</dd>
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<dt><code>.callinfo [ <var>param</var>=<var>value</var>, … ] [ <var>flag</var>, … ]</code></dt>
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<dd><p>Specify a number of parameters and flags that define the environment for a
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procedure.
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</p>
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<p><var>param</var> may be any of ‘<samp>frame</samp>’ (frame size), ‘<samp>entry_gr</samp>’ (end of
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general register range), ‘<samp>entry_fr</samp>’ (end of float register range),
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‘<samp>entry_sr</samp>’ (end of space register range).
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</p>
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<p>The values for <var>flag</var> are ‘<samp>calls</samp>’ or ‘<samp>caller</samp>’ (proc has
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subroutines), ‘<samp>no_calls</samp>’ (proc does not call subroutines), ‘<samp>save_rp</samp>’
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(preserve return pointer), ‘<samp>save_sp</samp>’ (proc preserves stack pointer),
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‘<samp>no_unwind</samp>’ (do not unwind this proc), ‘<samp>hpux_int</samp>’ (proc is interrupt
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routine).
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</p>
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</dd>
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<dt><code>.code</code></dt>
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<dd><p>Assemble into the standard section called ‘<samp>$TEXT$</samp>’, subsection
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‘<samp>$CODE$</samp>’.
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</p>
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</dd>
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<dt><code>.copyright "<var>string</var>"</code></dt>
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<dd><p>In the SOM object format, insert <var>string</var> into the object code, marked as a
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copyright string.
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</p>
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</dd>
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<dt><code>.copyright "<var>string</var>"</code></dt>
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<dd><p>In the ELF object format, insert <var>string</var> into the object code, marked as a
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version string.
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</p>
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</dd>
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<dt><code>.enter</code></dt>
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<dd><p>Not yet supported; the assembler rejects programs containing this directive.
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</p>
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</dd>
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<dt><code>.entry</code></dt>
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<dd><p>Mark the beginning of a procedure.
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</p>
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</dd>
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<dt><code>.exit</code></dt>
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<dd><p>Mark the end of a procedure.
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</p>
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</dd>
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<dt><code>.export <var>name</var> [ ,<var>typ</var> ] [ ,<var>param</var>=<var>r</var> ]</code></dt>
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<dd><p>Make a procedure <var>name</var> available to callers. <var>typ</var>, if present, must
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be one of ‘<samp>absolute</samp>’, ‘<samp>code</samp>’ (ELF only, not SOM), ‘<samp>data</samp>’,
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‘<samp>entry</samp>’, ‘<samp>data</samp>’, ‘<samp>entry</samp>’, ‘<samp>millicode</samp>’, ‘<samp>plabel</samp>’,
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‘<samp>pri_prog</samp>’, or ‘<samp>sec_prog</samp>’.
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</p>
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<p><var>param</var>, if present, provides either relocation information for the
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procedure arguments and result, or a privilege level. <var>param</var> may be
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‘<samp>argw<var>n</var></samp>’ (where <var>n</var> ranges from <code>0</code> to <code>3</code>, and
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indicates one of four one-word arguments); ‘<samp>rtnval</samp>’ (the procedure’s
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result); or ‘<samp>priv_lev</samp>’ (privilege level). For arguments or the result,
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<var>r</var> specifies how to relocate, and must be one of ‘<samp>no</samp>’ (not
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relocatable), ‘<samp>gr</samp>’ (argument is in general register), ‘<samp>fr</samp>’ (in
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floating point register), or ‘<samp>fu</samp>’ (upper half of float register).
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For ‘<samp>priv_lev</samp>’, <var>r</var> is an integer.
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</p>
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</dd>
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<dt><code>.half <var>n</var></code></dt>
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<dd><p>Define a two-byte integer constant <var>n</var>; synonym for the portable
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<code>as</code> directive <code>.short</code>.
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</p>
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</dd>
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<dt><code>.import <var>name</var> [ ,<var>typ</var> ]</code></dt>
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<dd><p>Converse of <code>.export</code>; make a procedure available to call. The arguments
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use the same conventions as the first two arguments for <code>.export</code>.
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</p>
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</dd>
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<dt><code>.label <var>name</var></code></dt>
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<dd><p>Define <var>name</var> as a label for the current assembly location.
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</p>
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</dd>
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<dt><code>.leave</code></dt>
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<dd><p>Not yet supported; the assembler rejects programs containing this directive.
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</p>
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</dd>
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<dt><code>.origin <var>lc</var></code></dt>
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<dd><p>Advance location counter to <var>lc</var>. Synonym for the <code>as</code>
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portable directive <code>.org</code>.
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</p>
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</dd>
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<dt><code>.param <var>name</var> [ ,<var>typ</var> ] [ ,<var>param</var>=<var>r</var> ]</code></dt>
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<dd><p>Similar to <code>.export</code>, but used for static procedures.
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</p>
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</dd>
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<dt><code>.proc</code></dt>
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<dd><p>Use preceding the first statement of a procedure.
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</p>
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</dd>
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<dt><code>.procend</code></dt>
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<dd><p>Use following the last statement of a procedure.
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</p>
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</dd>
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<dt><code><var>label</var> .reg <var>expr</var></code></dt>
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<dd><p>Synonym for <code>.equ</code>; define <var>label</var> with the absolute expression
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<var>expr</var> as its value.
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</p>
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</dd>
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<dt><code>.space <var>secname</var> [ ,<var>params</var> ]</code></dt>
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<dd><p>Switch to section <var>secname</var>, creating a new section by that name if
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necessary. You may only use <var>params</var> when creating a new section, not
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when switching to an existing one. <var>secname</var> may identify a section by
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number rather than by name.
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</p>
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<p>If specified, the list <var>params</var> declares attributes of the section,
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identified by keywords. The keywords recognized are ‘<samp>spnum=<var>exp</var></samp>’
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(identify this section by the number <var>exp</var>, an absolute expression),
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‘<samp>sort=<var>exp</var></samp>’ (order sections according to this sort key when linking;
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<var>exp</var> is an absolute expression), ‘<samp>unloadable</samp>’ (section contains no
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loadable data), ‘<samp>notdefined</samp>’ (this section defined elsewhere), and
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‘<samp>private</samp>’ (data in this section not available to other programs).
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</p>
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</dd>
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<dt><code>.spnum <var>secnam</var></code></dt>
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<dd><p>Allocate four bytes of storage, and initialize them with the section number of
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the section named <var>secnam</var>. (You can define the section number with the
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HPPA <code>.space</code> directive.)
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</p>
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<a name="index-string-directive-on-HPPA"></a>
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</dd>
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<dt><code>.string "<var>str</var>"</code></dt>
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<dd><p>Copy the characters in the string <var>str</var> to the object file.
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See <a href="Strings.html#Strings">Strings</a>, for information on escape sequences you can use in
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<code>as</code> strings.
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</p>
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<p><em>Warning!</em> The HPPA version of <code>.string</code> differs from the
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usual <code>as</code> definition: it does <em>not</em> write a zero byte
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after copying <var>str</var>.
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</p>
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</dd>
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<dt><code>.stringz "<var>str</var>"</code></dt>
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<dd><p>Like <code>.string</code>, but appends a zero byte after copying <var>str</var> to object
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file.
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</p>
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</dd>
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<dt><code>.subspa <var>name</var> [ ,<var>params</var> ]</code></dt>
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<dt><code>.nsubspa <var>name</var> [ ,<var>params</var> ]</code></dt>
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<dd><p>Similar to <code>.space</code>, but selects a subsection <var>name</var> within the
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current section. You may only specify <var>params</var> when you create a
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subsection (in the first instance of <code>.subspa</code> for this <var>name</var>).
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</p>
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<p>If specified, the list <var>params</var> declares attributes of the subsection,
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identified by keywords. The keywords recognized are ‘<samp>quad=<var>expr</var></samp>’
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(“quadrant” for this subsection), ‘<samp>align=<var>expr</var></samp>’ (alignment for
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beginning of this subsection; a power of two), ‘<samp>access=<var>expr</var></samp>’ (value
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for “access rights” field), ‘<samp>sort=<var>expr</var></samp>’ (sorting order for this
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subspace in link), ‘<samp>code_only</samp>’ (subsection contains only code),
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‘<samp>unloadable</samp>’ (subsection cannot be loaded into memory), ‘<samp>comdat</samp>’
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(subsection is comdat), ‘<samp>common</samp>’ (subsection is common block),
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‘<samp>dup_comm</samp>’ (subsection may have duplicate names), or ‘<samp>zero</samp>’
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(subsection is all zeros, do not write in object file).
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</p>
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<p><code>.nsubspa</code> 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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</p>
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<p>‘<samp>comdat</samp>’, ‘<samp>common</samp>’ and ‘<samp>dup_comm</samp>’ can be used to implement
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various flavors of one-only support when using the SOM linker. The SOM
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linker only supports specific combinations of these flags. The details
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are not documented. A brief description is provided here.
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</p>
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<p>‘<samp>comdat</samp>’ provides a form of linkonce support. It is useful for
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both code and data subspaces. A ‘<samp>comdat</samp>’ subspace has a key symbol
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marked by the ‘<samp>is_comdat</samp>’ flag or ‘<samp>ST_COMDAT</samp>’. Only the first
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subspace for any given key is selected. The key symbol becomes universal
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in shared links. This is similar to the behavior of ‘<samp>secondary_def</samp>’
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symbols.
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</p>
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<p>‘<samp>common</samp>’ provides Fortran named common support. It is only useful
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for data subspaces. Symbols with the flag ‘<samp>is_common</samp>’ retain this
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flag in shared links. Referencing a ‘<samp>is_common</samp>’ symbol in a shared
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library from outside the library doesn’t work. Thus, ‘<samp>is_common</samp>’
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symbols must be output whenever they are needed.
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</p>
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<p>‘<samp>common</samp>’ and ‘<samp>dup_comm</samp>’ together provide Cobol common support.
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The subspaces in this case must all be the same length. Otherwise, this
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support is similar to the Fortran common support.
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</p>
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<p>‘<samp>dup_comm</samp>’ by itself provides a type of one-only support for code.
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Only the first ‘<samp>dup_comm</samp>’ subspace is selected. There is a rather
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complex algorithm to compare subspaces. Code symbols marked with the
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‘<samp>dup_common</samp>’ flag are hidden. This support was intended for "C++
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duplicate inlines".
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</p>
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<p>A simplified technique is used to mark the flags of symbols based on
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the flags of their subspace. A symbol with the scope SS_UNIVERSAL and
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type ST_ENTRY, ST_CODE or ST_DATA is marked with the corresponding
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settings of ‘<samp>comdat</samp>’, ‘<samp>common</samp>’ and ‘<samp>dup_comm</samp>’ from the
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subspace, respectively. This avoids having to introduce additional
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directives to mark these symbols. The HP assembler sets ‘<samp>is_common</samp>’
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from ‘<samp>common</samp>’. However, it doesn’t set the ‘<samp>dup_common</samp>’ from
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‘<samp>dup_comm</samp>’. It doesn’t have ‘<samp>comdat</samp>’ support.
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</p>
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</dd>
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<dt><code>.version "<var>str</var>"</code></dt>
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<dd><p>Write <var>str</var> as version identifier in object code.
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</p></dd>
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</dl>
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<hr>
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<div class="header">
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<p>
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Next: <a href="HPPA-Opcodes.html#HPPA-Opcodes" accesskey="n" rel="next">HPPA Opcodes</a>, Previous: <a href="HPPA-Floating-Point.html#HPPA-Floating-Point" accesskey="p" rel="prev">HPPA Floating Point</a>, Up: <a href="HPPA_002dDependent.html#HPPA_002dDependent" accesskey="u" rel="up">HPPA-Dependent</a> [<a href="index.html#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="AS-Index.html#AS-Index" title="Index" rel="index">Index</a>]</p>
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