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<title>H8/300-Addressing (Using as)</title>
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<a name="H8_002f300_002dAddressing"></a>
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<p>
Previous: <a href="H8_002f300_002dRegs.html#H8_002f300_002dRegs" accesskey="p" rel="prev">H8/300-Regs</a>, Up: <a href="H8_002f300-Syntax.html#H8_002f300-Syntax" accesskey="u" rel="up">H8/300 Syntax</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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<hr>
<a name="Addressing-Modes-2"></a>
<h4 class="subsubsection">9.13.2.3 Addressing Modes</h4>
<a name="index-addressing-modes_002c-H8_002f300"></a>
<a name="index-H8_002f300-addressing-modes"></a>
<p>as understands the following addressing modes for the H8/300:
</p><dl compact="compact">
<dt><code>r<var>n</var></code></dt>
<dd><p>Register direct
</p>
</dd>
<dt><code>@r<var>n</var></code></dt>
<dd><p>Register indirect
</p>
</dd>
<dt><code>@(<var>d</var>, r<var>n</var>)</code></dt>
<dt><code>@(<var>d</var>:16, r<var>n</var>)</code></dt>
<dt><code>@(<var>d</var>:24, r<var>n</var>)</code></dt>
<dd><p>Register indirect: 16-bit or 24-bit displacement <var>d</var> from register
<var>n</var>. (24-bit displacements are only meaningful on the H8/300H.)
</p>
</dd>
<dt><code>@r<var>n</var>+</code></dt>
<dd><p>Register indirect with post-increment
</p>
</dd>
<dt><code>@-r<var>n</var></code></dt>
<dd><p>Register indirect with pre-decrement
</p>
</dd>
<dt><code><code>@</code><var>aa</var></code></dt>
<dt><code><code>@</code><var>aa</var>:8</code></dt>
<dt><code><code>@</code><var>aa</var>:16</code></dt>
<dt><code><code>@</code><var>aa</var>:24</code></dt>
<dd><p>Absolute address <code>aa</code>. (The address size ‘<samp>:24</samp>’ only makes
sense on the H8/300H.)
</p>
</dd>
<dt><code>#<var>xx</var></code></dt>
<dt><code>#<var>xx</var>:8</code></dt>
<dt><code>#<var>xx</var>:16</code></dt>
<dt><code>#<var>xx</var>:32</code></dt>
<dd><p>Immediate data <var>xx</var>. You may specify the ‘<samp>:8</samp>’, ‘<samp>:16</samp>’, or
‘<samp>:32</samp>’ for clarity, if you wish; but <code>as</code> neither
requires this nor uses it—the data size required is taken from
context.
</p>
</dd>
<dt><code><code>@</code><code>@</code><var>aa</var></code></dt>
<dt><code><code>@</code><code>@</code><var>aa</var>:8</code></dt>
<dd><p>Memory indirect. You may specify the ‘<samp>:8</samp>’ for clarity, if you
wish; but <code>as</code> neither requires this nor uses it.
</p></dd>
</dl>
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