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<title>if-<test>z</title>
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<h1>if-<test>z</h1>
<h2>Purpose</h2>
<p>
Branch to the given destination if the given register's value compares with 0
as specified.
</p>
<p>
Note: The branch offset may not be 0. (A spin loop may be legally constructed
either by branching around a backward goto or by including a nop as a target
before the branch.)
</p>
<h2>Details</h2>
<table class="instruc">
<thead>
<tr>
<th>Op & Format</th>
<th>Mnemonic / Syntax</th>
<th>Arguments</th>
</tr>
</thead>
<tbody>
<tr>
<td>38..3d 21t</td>
<td>if-<i>test</i>z vAA, +BBBB<br/>
38: if-eqz<br/>
39: if-nez<br/>
3a: if-ltz<br/>
3b: if-gez<br/>
3c: if-gtz<br/>
3d: if-lez<br/>
</td>
<td><code>A:</code> register to test (8 bits)<br/>
<code>B:</code> signed branch offset (16 bits)</td>
</tr>
</tbody>
</table>
<h2>Constraints</h2>
<ul>
<li>
A must be a valid register index for the current stackframe.
</li>
<li>
Register vA must not contain a reference value.
</li>
<li>
Register vA must not be part of a register pair.
</li>
<li>
Register vA must not contain a floating point value (???).
</li>
<li>
B must not be 0.
</li>
</ul>
<h2>Behavior</h2>
<ul>
<li>
The value of register vA is compared to zero according to the <test>
condition. Two results are possible:
<ul>
<li>
The condition holds. The value of B is used as a signed offset to the
address of the if-<test>z instruction. Execution continues at the
resulting address.
</li>
<li>
The condition does not hold. Execution continues at the instruction
following the if-<test>z instruction.
</li>
</ul>
</li>
</ul>
<h2>Exceptions</h2>
<p>
None.
</p>
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