forked from NRZCode/ia32-64
57 lines
2.2 KiB
HTML
57 lines
2.2 KiB
HTML
<!DOCTYPE html>
|
||
<html xmlns="http://www.w3.org/1999/xhtml" xmlns:svg="http://www.w3.org/2000/svg" xmlns:x86="http://www.felixcloutier.com/x86"><head><meta http-equiv="Content-Type" content="text/html; charset=UTF-8"><link rel="stylesheet" type="text/css" href="style.css"></link><title>STD
|
||
— Set Direction Flag</title></head><body><header><nav><ul><li><a href='index.html'>Index</a></li><li>December 2023</li></ul></nav></header><h1>STD
|
||
— Set Direction Flag</h1>
|
||
|
||
<table>
|
||
<tr>
|
||
<th>Opcode</th>
|
||
<th>Instruction</th>
|
||
<th>Op/En</th>
|
||
<th>64-bit Mode</th>
|
||
<th>Compat/Leg Mode</th>
|
||
<th>Description</th></tr>
|
||
<tr>
|
||
<td>FD</td>
|
||
<td>STD</td>
|
||
<td>ZO</td>
|
||
<td>Valid</td>
|
||
<td>Valid</td>
|
||
<td>Set DF flag.</td></tr></table>
|
||
<h2 id="instruction-operand-encoding">Instruction Operand Encoding<a class="anchor" href="#instruction-operand-encoding">
|
||
¶
|
||
</a></h2>
|
||
<table>
|
||
<tr>
|
||
<th>Op/En</th>
|
||
<th>Operand 1</th>
|
||
<th>Operand 2</th>
|
||
<th>Operand 3</th>
|
||
<th>Operand 4</th></tr>
|
||
<tr>
|
||
<td>ZO</td>
|
||
<td>N/A</td>
|
||
<td>N/A</td>
|
||
<td>N/A</td>
|
||
<td>N/A</td></tr></table>
|
||
<h2 id="description">Description<a class="anchor" href="#description">
|
||
¶
|
||
</a></h2>
|
||
<p>Sets the DF flag in the EFLAGS register. When the DF flag is set to 1, string operations decrement the index registers (ESI and/or EDI). Operation is the same in all modes.</p>
|
||
<h2 id="operation">Operation<a class="anchor" href="#operation">
|
||
¶
|
||
</a></h2>
|
||
<pre>DF := 1;
|
||
</pre>
|
||
<h2 id="flags-affected">Flags Affected<a class="anchor" href="#flags-affected">
|
||
¶
|
||
</a></h2>
|
||
<p>The DF flag is set. The CF, OF, ZF, SF, AF, and PF flags are unaffected.</p>
|
||
<h2 id="exceptions--all-operating-modes-">Exceptions (All Operating Modes)<a class="anchor" href="#exceptions--all-operating-modes-">
|
||
¶
|
||
</a></h2>
|
||
<p>#UD If the LOCK prefix is used.</p><footer><p>
|
||
This UNOFFICIAL, mechanically-separated, non-verified reference is provided for convenience, but it may be
|
||
inc<span style="opacity: 0.2">omp</span>lete or b<sub>r</sub>oke<sub>n</sub> in various obvious or non-obvious
|
||
ways. Refer to <a href="https://software.intel.com/en-us/download/intel-64-and-ia-32-architectures-sdm-combined-volumes-1-2a-2b-2c-2d-3a-3b-3c-3d-and-4">Intel® 64 and IA-32 Architectures Software Developer’s Manual</a> for anything serious.
|
||
</p></footer></body></html>
|