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<title>Using as: Xtensa Registers</title>
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Previous: <a href="Xtensa-Opcodes.html#Xtensa-Opcodes" accesskey="p" rel="prev">Xtensa Opcodes</a>, Up: <a href="Xtensa-Syntax.html#Xtensa-Syntax" accesskey="u" rel="up">Xtensa Syntax</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="Register-Names-20"></a>
<h4 class="subsubsection">9.52.2.2 Register Names</h4>
<a name="index-Xtensa-register-names"></a>
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<a name="index-sp-register"></a>
<p>The assembly syntax for a register file entry is the &ldquo;short&rdquo; name for
a TIE register file followed by the index into that register file. For
example, the general-purpose <code>AR</code> register file has a short name of
<code>a</code>, so these registers are named <code>a0</code>&hellip;<code>a15</code>.
As a special feature, <code>sp</code> is also supported as a synonym for
<code>a1</code>. Additional registers may be added by processor configuration
options and by designer-defined TIE extensions. An initial &lsquo;<samp>$</samp>&rsquo;
character is optional in all register names.
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