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<title>M68K-Syntax (Using as)</title>

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<a name="M68K_002dSyntax"></a>
<div class="header">
<p>
Next: <a href="M68K_002dMoto_002dSyntax.html#M68K_002dMoto_002dSyntax" accesskey="n" rel="next">M68K-Moto-Syntax</a>, Previous: <a href="M68K_002dOpts.html#M68K_002dOpts" accesskey="p" rel="prev">M68K-Opts</a>, Up: <a href="M68K_002dDependent.html#M68K_002dDependent" accesskey="u" rel="up">M68K-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="Syntax-17"></a>
<h4 class="subsection">9.22.2 Syntax</h4>

<a name="index-MIT"></a>
<p>This syntax for the Motorola 680x0 was developed at <small>MIT</small>.
</p>
<a name="index-M680x0-syntax"></a>
<a name="index-syntax_002c-M680x0"></a>
<a name="index-M680x0-size-modifiers"></a>
<a name="index-size-modifiers_002c-M680x0"></a>
<p>The 680x0 version of <code>as</code> uses instructions names and
syntax compatible with the Sun assembler.  Intervening periods are
ignored; for example, &lsquo;<samp>movl</samp>&rsquo; is equivalent to &lsquo;<samp>mov.l</samp>&rsquo;.
</p>
<p>In the following table <var>apc</var> stands for any of the address registers
(&lsquo;<samp>%a0</samp>&rsquo; through &lsquo;<samp>%a7</samp>&rsquo;), the program counter (&lsquo;<samp>%pc</samp>&rsquo;), the
zero-address relative to the program counter (&lsquo;<samp>%zpc</samp>&rsquo;), a suppressed
address register (&lsquo;<samp>%za0</samp>&rsquo; through &lsquo;<samp>%za7</samp>&rsquo;), or it may be omitted
entirely.  The use of <var>size</var> means one of &lsquo;<samp>w</samp>&rsquo; or &lsquo;<samp>l</samp>&rsquo;, and
it may be omitted, along with the leading colon, unless a scale is also
specified.  The use of <var>scale</var> means one of &lsquo;<samp>1</samp>&rsquo;, &lsquo;<samp>2</samp>&rsquo;,
&lsquo;<samp>4</samp>&rsquo;, or &lsquo;<samp>8</samp>&rsquo;, and it may always be omitted along with the
leading colon.
</p>
<a name="index-M680x0-addressing-modes"></a>
<a name="index-addressing-modes_002c-M680x0"></a>
<p>The following addressing modes are understood:
</p><dl compact="compact">
<dt><em>Immediate</em></dt>
<dd><p>&lsquo;<samp>#<var>number</var></samp>&rsquo;
</p>
</dd>
<dt><em>Data Register</em></dt>
<dd><p>&lsquo;<samp>%d0</samp>&rsquo; through &lsquo;<samp>%d7</samp>&rsquo;
</p>
</dd>
<dt><em>Address Register</em></dt>
<dd><p>&lsquo;<samp>%a0</samp>&rsquo; through &lsquo;<samp>%a7</samp>&rsquo;<br>
&lsquo;<samp>%a7</samp>&rsquo; is also known as &lsquo;<samp>%sp</samp>&rsquo;, i.e., the Stack Pointer.  <code>%a6</code>
is also known as &lsquo;<samp>%fp</samp>&rsquo;, the Frame Pointer.
</p>
</dd>
<dt><em>Address Register Indirect</em></dt>
<dd><p>&lsquo;<samp>%a0@</samp>&rsquo; through &lsquo;<samp>%a7@</samp>&rsquo;
</p>
</dd>
<dt><em>Address Register Postincrement</em></dt>
<dd><p>&lsquo;<samp>%a0@+</samp>&rsquo; through &lsquo;<samp>%a7@+</samp>&rsquo;
</p>
</dd>
<dt><em>Address Register Predecrement</em></dt>
<dd><p>&lsquo;<samp>%a0@-</samp>&rsquo; through &lsquo;<samp>%a7@-</samp>&rsquo;
</p>
</dd>
<dt><em>Indirect Plus Offset</em></dt>
<dd><p>&lsquo;<samp><var>apc</var>@(<var>number</var>)</samp>&rsquo;
</p>
</dd>
<dt><em>Index</em></dt>
<dd><p>&lsquo;<samp><var>apc</var>@(<var>number</var>,<var>register</var>:<var>size</var>:<var>scale</var>)</samp>&rsquo;
</p>
<p>The <var>number</var> may be omitted.
</p>
</dd>
<dt><em>Postindex</em></dt>
<dd><p>&lsquo;<samp><var>apc</var>@(<var>number</var>)@(<var>onumber</var>,<var>register</var>:<var>size</var>:<var>scale</var>)</samp>&rsquo;
</p>
<p>The <var>onumber</var> or the <var>register</var>, but not both, may be omitted.
</p>
</dd>
<dt><em>Preindex</em></dt>
<dd><p>&lsquo;<samp><var>apc</var>@(<var>number</var>,<var>register</var>:<var>size</var>:<var>scale</var>)@(<var>onumber</var>)</samp>&rsquo;
</p>
<p>The <var>number</var> may be omitted.  Omitting the <var>register</var> produces
the Postindex addressing mode.
</p>
</dd>
<dt><em>Absolute</em></dt>
<dd><p>&lsquo;<samp><var>symbol</var></samp>&rsquo;, or &lsquo;<samp><var>digits</var></samp>&rsquo;, optionally followed by
&lsquo;<samp>:b</samp>&rsquo;, &lsquo;<samp>:w</samp>&rsquo;, or &lsquo;<samp>:l</samp>&rsquo;.
</p></dd>
</dl>

<hr>
<div class="header">
<p>
Next: <a href="M68K_002dMoto_002dSyntax.html#M68K_002dMoto_002dSyntax" accesskey="n" rel="next">M68K-Moto-Syntax</a>, Previous: <a href="M68K_002dOpts.html#M68K_002dOpts" accesskey="p" rel="prev">M68K-Opts</a>, Up: <a href="M68K_002dDependent.html#M68K_002dDependent" accesskey="u" rel="up">M68K-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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