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STD.htm
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<!DOCTYPE HTML PUBLIC "-//IETF//DTD HTML 2.0//EN">
<HTML>
<HEAD>
<TITLE>80386 Programmer's Reference Manual -- Opcode STD</TITLE>
</HEAD>
<BODY>
<B>up:</B> <A HREF="c17.htm">
Chapter 17 -- 80386 Instruction Set</A><BR>
<B>prev:</B><A HREF="STC.htm"> STC Set Carry Flag</A><BR>
<B>next:</B><A HREF="STI.htm"> STI Set Interrupt Flag</A>
<P>
<HR>
<P>
<H1>STD -- Set Direction Flag</H1>
<PRE>
Opcode Instruction Clocks Description
FD STD 2 Set direction flag so (E)SI and/or (E)DI
decrement
</PRE>
<H2>Operation</H2>
<PRE>
DF := 1;
</PRE>
<H2>Description</H2>
STD sets the direction flag to 1, causing all subsequent string operations
to decrement the index registers, (E)SI and/or (E)DI, on which they
operate.
<H2>Flags Affected</H2>
DF := 1
<H2>Protected Mode Exceptions</H2>
None
<H2>Real Address Mode Exceptions</H2>
None
<H2>Virtual 8086 Mode Exceptions</H2>
None
<P>
<HR>
<P>
<B>up:</B> <A HREF="c17.htm">
Chapter 17 -- 80386 Instruction Set</A><BR>
<B>prev:</B><A HREF="STC.htm"> STC Set Carry Flag</A><BR>
<B>next:</B><A HREF="STI.htm"> STI Set Interrupt Flag</A>
</BODY>