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<title>Using as: HPPA Directives</title>

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<a name="HPPA-Directives"></a>
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<p>
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> &nbsp; [<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>
</div>
<hr>
<a name="HPPA-Assembler-Directives"></a>
<h4 class="subsection">9.13.5 HPPA Assembler Directives</h4>

<p><code>as</code> for the HPPA supports many additional directives for
compatibility with the native assembler.  This section describes them only
briefly.  For detailed information on HPPA-specific assembler directives, see
<cite>HP9000 Series 800 Assembly Language Reference Manual</cite> (HP 92432-90001).
</p>
<a name="index-HPPA-directives-not-supported"></a>
<p><code>as</code> does <em>not</em> support the following assembler directives
described in the HP manual:
</p>
<div class="example">
<pre class="example">.endm           .liston
.enter          .locct
.leave          .macro
.listoff
</pre></div>

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

<hr>
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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> &nbsp; [<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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