forked from NRZCode/ia32-64
57 lines
2.3 KiB
HTML
57 lines
2.3 KiB
HTML
<!DOCTYPE html>
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<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>CLD
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— Clear Direction Flag</title></head><body><header><nav><ul><li><a href='index.html'>Index</a></li><li>December 2023</li></ul></nav></header><h1>CLD
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— Clear Direction Flag</h1>
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<table>
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<tr>
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<th>Opcode</th>
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<th>Instruction</th>
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<th>Op/En</th>
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<th>64-bit Mode</th>
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<th>Compat/Leg Mode</th>
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<th>Description</th></tr>
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<tr>
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<td>FC</td>
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<td>CLD</td>
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<td>ZO</td>
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<td>Valid</td>
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<td>Valid</td>
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<td>Clear DF flag.</td></tr></table>
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<h2 id="instruction-operand-encoding">Instruction Operand Encoding<a class="anchor" href="#instruction-operand-encoding">
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¶
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</a></h2>
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<table>
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<tr>
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<th>Op/En</th>
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<th>Operand 1</th>
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<th>Operand 2</th>
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<th>Operand 3</th>
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<th>Operand 4</th></tr>
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<tr>
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<td>ZO</td>
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<td>N/A</td>
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<td>N/A</td>
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<td>N/A</td>
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<td>N/A</td></tr></table>
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<h2 id="description">Description<a class="anchor" href="#description">
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¶
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</a></h2>
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<p>Clears the DF flag in the EFLAGS register. When the DF flag is set to 0, string operations increment the index registers (ESI and/or EDI). Operation is the same in all modes.</p>
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<h2 id="operation">Operation<a class="anchor" href="#operation">
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¶
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</a></h2>
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<pre>DF := 0;
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</pre>
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<h2 id="flags-affected">Flags Affected<a class="anchor" href="#flags-affected">
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¶
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</a></h2>
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<p>The DF flag is set to 0. The CF, OF, ZF, SF, AF, and PF flags are unaffected.</p>
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<h2 id="exceptions--all-operating-modes-">Exceptions (All Operating Modes)<a class="anchor" href="#exceptions--all-operating-modes-">
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¶
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</a></h2>
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<p>#UD If the LOCK prefix is used.</p><footer><p>
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This UNOFFICIAL, mechanically-separated, non-verified reference is provided for convenience, but it may be
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inc<span style="opacity: 0.2">omp</span>lete or b<sub>r</sub>oke<sub>n</sub> in various obvious or non-obvious
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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.
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</p></footer></body></html>
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