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<a name="AVR_002dModifiers"></a>
<div class="header">
<p>
Previous: <a href="AVR_002dRegs.html#AVR_002dRegs" accesskey="p" rel="prev">AVR-Regs</a>, Up: <a href="AVR-Syntax.html#AVR-Syntax" accesskey="u" rel="up">AVR 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>
</div>
<hr>
<a name="Relocatable-Expression-Modifiers"></a>
<h4 class="subsubsection">9.5.2.3 Relocatable Expression Modifiers</h4>

<a name="index-AVR-modifiers"></a>
<a name="index-syntax_002c-AVR"></a>

<p>The assembler supports several modifiers when using relocatable addresses
in AVR instruction operands.  The general syntax is the following:
</p>
<div class="smallexample">
<pre class="smallexample">modifier(relocatable-expression)
</pre></div>

<dl compact="compact">
<dd><a name="index-symbol-modifiers"></a>

</dd>
<dt><code>lo8</code></dt>
<dd>
<p>This modifier allows you to use bits 0 through 7 of
an address expression as an 8 bit relocatable expression.
</p>
</dd>
<dt><code>hi8</code></dt>
<dd>
<p>This modifier allows you to use bits 7 through 15 of an address expression
as an 8 bit relocatable expression. This is useful with, for example, the
AVR &lsquo;<samp>ldi</samp>&rsquo; instruction and &lsquo;<samp>lo8</samp>&rsquo; modifier.
</p>
<p>For example
</p>
<div class="smallexample">
<pre class="smallexample">ldi r26, lo8(sym+10)
ldi r27, hi8(sym+10)
</pre></div>

</dd>
<dt><code>hh8</code></dt>
<dd>
<p>This modifier allows you to use bits 16 through 23 of
an address expression as an 8 bit relocatable expression.
Also, can be useful for loading 32 bit constants.
</p>
</dd>
<dt><code>hlo8</code></dt>
<dd>
<p>Synonym of &lsquo;<samp>hh8</samp>&rsquo;.
</p>
</dd>
<dt><code>hhi8</code></dt>
<dd>
<p>This modifier allows you to use bits 24 through 31 of
an expression as an 8 bit expression. This is useful with, for example, the
AVR &lsquo;<samp>ldi</samp>&rsquo; instruction and &lsquo;<samp>lo8</samp>&rsquo;, &lsquo;<samp>hi8</samp>&rsquo;, &lsquo;<samp>hlo8</samp>&rsquo;,
&lsquo;<samp>hhi8</samp>&rsquo;, modifier.
</p>
<p>For example
</p>
<div class="smallexample">
<pre class="smallexample">ldi r26, lo8(285774925)
ldi r27, hi8(285774925)
ldi r28, hlo8(285774925)
ldi r29, hhi8(285774925)
; r29,r28,r27,r26 = 285774925
</pre></div>

</dd>
<dt><code>pm_lo8</code></dt>
<dd>
<p>This modifier allows you to use bits 0 through 7 of
an address expression as an 8 bit relocatable expression.
This modifier is useful for addressing data or code from
Flash/Program memory by two-byte words. The use of &lsquo;<samp>pm_lo8</samp>&rsquo;
is similar to &lsquo;<samp>lo8</samp>&rsquo;.
</p>
</dd>
<dt><code>pm_hi8</code></dt>
<dd>
<p>This modifier allows you to use bits 8 through 15 of
an address expression as an 8 bit relocatable expression.
This modifier is useful for addressing data or code from
Flash/Program memory by two-byte words.
</p>
<p>For example, when setting the AVR &lsquo;<samp>Z</samp>&rsquo; register with the &lsquo;<samp>ldi</samp>&rsquo;
instruction for subsequent use by the &lsquo;<samp>ijmp</samp>&rsquo; instruction:
</p>
<div class="smallexample">
<pre class="smallexample">ldi r30, pm_lo8(sym)
ldi r31, pm_hi8(sym)
ijmp
</pre></div>

</dd>
<dt><code>pm_hh8</code></dt>
<dd>
<p>This modifier allows you to use bits 15 through 23 of
an address expression as an 8 bit relocatable expression.
This modifier is useful for addressing data or code from
Flash/Program memory by two-byte words.
</p>
</dd>
</dl>

<hr>
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