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<title>STD: Set Direction Flag (x86 Instruction Set Reference)</title>
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<div class="main_container"><h1>x86 Instruction Set Reference</h1>
<title>STD: Set Direction Flag (x86 Instruction Set Reference)</title>
<h1>STD</h1>
<h2>Set Direction Flag</h2>
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<th>Opcode</th>
<th>Mnemonic</th>
<th>Description</th>
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<td class="grid"><code>FD</code></td>
<td class="grid"><code>STD</code></td>
<td class="grid">Set DF flag.</td>
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<th>Description</th>
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<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).</p>
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<pre>DF <span class="operator">=</span> <span class="number">1</span><span class="operator">;</span>
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<th>Flags affected</th>
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<p>The DF flag is set. The CF, OF, ZF, SF, AF, and PF flags are unaffected.
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