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<title>Using as: ARM Mapping Symbols</title>

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<a name="ARM-Mapping-Symbols"></a>
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Next: <a href="ARM-Unwinding-Tutorial.html#ARM-Unwinding-Tutorial" accesskey="n" rel="next">ARM Unwinding Tutorial</a>, Previous: <a href="ARM-Opcodes.html#ARM-Opcodes" accesskey="p" rel="prev">ARM Opcodes</a>, Up: <a href="ARM_002dDependent.html#ARM_002dDependent" accesskey="u" rel="up">ARM-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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<a name="Mapping-Symbols-1"></a>
<h4 class="subsection">9.4.6 Mapping Symbols</h4>

<p>The ARM ELF specification requires that special symbols be inserted
into object files to mark certain features:
</p>
<dl compact="compact">
<dd>
<a name="index-_0024a"></a>
</dd>
<dt><code>$a</code></dt>
<dd><p>At the start of a region of code containing ARM instructions.
</p>
<a name="index-_0024t"></a>
</dd>
<dt><code>$t</code></dt>
<dd><p>At the start of a region of code containing THUMB instructions.
</p>
<a name="index-_0024d-1"></a>
</dd>
<dt><code>$d</code></dt>
<dd><p>At the start of a region of data.
</p>
</dd>
</dl>

<p>The assembler will automatically insert these symbols for you - there
is no need to code them yourself.  Support for tagging symbols ($b,
$f, $p and $m) which is also mentioned in the current ARM ELF
specification is not implemented.  This is because they have been
dropped from the new EABI and so tools cannot rely upon their
presence.
</p>


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