sti.htm
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<!DOCTYPE HTML PUBLIC "-//IETF//DTD HTML 2.0//EN"><HTML><HEAD><TITLE>80386 Programmer's Reference Manual -- Opcode STI</TITLE></HEAD><BODY><B>up:</B> <A HREF="c17.htm">Chapter 17 -- 80386 Instruction Set</A><BR><B>prev:</B><A HREF="STD.htm"> STD Set Direction Flag</A><BR><B>next:</B><A HREF="STOS.htm"> STOS/STOSB/STOSW/STOSD Store String Data</A><P><HR><P><H1>STI -- Set Interrupt Flag</H1><PRE>Opcode Instruction Clocks DescriptionF13 STI 3 Set interrupt flag; interrupts enabled at the end of the next instruction</PRE><H2>Operation</H2><PRE>IF := 1</PRE><H2>Description</H2>STI sets the interrupt flag to 1. The 80386 then responds to externalinterrupts after executing the next instruction if the next instructionallows the interrupt flag to remain enabled. If external interrupts aredisabled and you code STI, <A HREF="RET.htm">RET</A> (such as at the end of a subroutine),the <A HREF="RET.htm">RET</A> is allowed to execute before external interrupts are recognized.Also, if external interrupts are disabled and you code STI, <A HREF="CLI.htm">CLI</A>, thenexternal interrupts are not recognized because the <A HREF="CLI.htm">CLI</A> instruction clearsthe interrupt flag during its execution.<H2>Flags Affected</H2>IF := 1<H2>Protected Mode Exceptions</H2>#GP(0) if the current privilege level is greater (has less privilege) thanthe I/O privilege level<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="STD.htm"> STD Set Direction Flag</A><BR><B>next:</B><A HREF="STOS.htm"> STOS/STOSB/STOSW/STOSD Store String Data</A></BODY>⌨️ 快捷键说明
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