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<a name="Word"></a>
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<p>
Next: <a href="Zero.html#Zero" accesskey="n" rel="next">Zero</a>, Previous: <a href="Weakref.html#Weakref" accesskey="p" rel="prev">Weakref</a>, Up: <a href="Pseudo-Ops.html#Pseudo-Ops" accesskey="u" rel="up">Pseudo Ops</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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<a name="g_t_002eword-expressions"></a>
<h3 class="section">7.103 <code>.word <var>expressions</var></code></h3>
<a name="index-word-directive"></a>
<p>This directive expects zero or more <var>expressions</var>, of any section,
separated by commas.
</p>
<p>The size of the number emitted, and its byte order,
depend on what target computer the assembly is for.
</p>
<a name="index-difference-tables-altered"></a>
<a name="index-altered-difference-tables"></a>
<blockquote>
<p><em>Warning: Special Treatment to support Compilers</em>
</p></blockquote>
<p>Machines with a 32-bit address space, but that do less than 32-bit
addressing, require the following special treatment. If the machine of
interest to you does 32-bit addressing (or doesn’t require it;
see <a href="Machine-Dependencies.html#Machine-Dependencies">Machine Dependencies</a>), you can ignore this issue.
</p>
<p>In order to assemble compiler output into something that works,
<code>as</code> occasionally does strange things to ‘<samp>.word</samp>’ directives.
Directives of the form ‘<samp>.word sym1-sym2</samp>’ are often emitted by
compilers as part of jump tables. Therefore, when <code>as</code> assembles a
directive of the form ‘<samp>.word sym1-sym2</samp>’, and the difference between
<code>sym1</code> and <code>sym2</code> does not fit in 16 bits, <code>as</code>
creates a <em>secondary jump table</em>, immediately before the next label.
This secondary jump table is preceded by a short-jump to the
first byte after the secondary table. This short-jump prevents the flow
of control from accidentally falling into the new table. Inside the
table is a long-jump to <code>sym2</code>. The original ‘<samp>.word</samp>’
contains <code>sym1</code> minus the address of the long-jump to
<code>sym2</code>.
</p>
<p>If there were several occurrences of ‘<samp>.word sym1-sym2</samp>’ before the
secondary jump table, all of them are adjusted. If there was a
‘<samp>.word sym3-sym4</samp>’, that also did not fit in sixteen bits, a
long-jump to <code>sym4</code> is included in the secondary jump table,
and the <code>.word</code> directives are adjusted to contain <code>sym3</code>
minus the address of the long-jump to <code>sym4</code>; and so on, for as many
entries in the original jump table as necessary.
</p>
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