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Next: <a href="ARM_002dChars.html#ARM_002dChars" accesskey="n" rel="next">ARM-Chars</a>, Up: <a href="ARM-Syntax.html#ARM-Syntax" accesskey="u" rel="up">ARM 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="Instruction-Set-Syntax"></a>
<h4 class="subsubsection">9.4.2.1 Instruction Set Syntax</h4>
<p>Two slightly different syntaxes are support for ARM and THUMB
instructions.  The default, <code>divided</code>, uses the old style where
ARM and THUMB instructions had their own, separate syntaxes.  The new,
<code>unified</code> syntax, which can be selected via the <code>.syntax</code>
directive, and has the following main features:
</p>
<ul>
<li> Immediate operands do not require a <code>#</code> prefix.

</li><li> The <code>IT</code> instruction may appear, and if it does it is validated
against subsequent conditional affixes.  In ARM mode it does not
generate machine code, in THUMB mode it does.

</li><li> For ARM instructions the conditional affixes always appear at the end
of the instruction.  For THUMB instructions conditional affixes can be
used, but only inside the scope of an <code>IT</code> instruction.

</li><li> All of the instructions new to the V6T2 architecture (and later) are
available.  (Only a few such instructions can be written in the
<code>divided</code> syntax).

</li><li> The <code>.N</code> and <code>.W</code> suffixes are recognized and honored.

</li><li> All instructions set the flags if and only if they have an <code>s</code>
affix.
</li></ul>


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