60 lines
2.4 KiB
HTML
60 lines
2.4 KiB
HTML
<html><!DOCTYPE HTML PUBLIC "-//IETF//DTD HTML 2.0//EN">
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<html>
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<head>
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<title>80386 Programmer's Reference Manual -- Opcode LEAVE</title>
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</head>
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<body>
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<b>up:</b> <a href="C17.HTM" tppabs="http://webster.cs.ucr.edu/Page_TechDocs/Doc386/C17.HTM">Chapter 17 -- 80386 Instruction Set</a><br>
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<b>prev:</b><a href="LEA.HTM" tppabs="http://webster.cs.ucr.edu/Page_TechDocs/Doc386/LEA.HTM"> LEA Load Effective Address</a><br>
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<b>next:</b><a href="LGDT.HTM" tppabs="http://webster.cs.ucr.edu/Page_TechDocs/Doc386/LGDT.HTM"> LGDT/LIDT Load Global/Interrupt Descriptor Table Register</a>
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<p>
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<hr>
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<p>
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<h1>LEAVE -- High Level Procedure Exit</h1>
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<pre>
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Opcode Instruction Clocks Description
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C9 LEAVE 4 Set SP to BP, then pop BP
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C9 LEAVE 4 Set ESP to EBP, then pop EBP
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</pre>
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<h2>Operation</h2>
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<pre>
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IF StackAddrSize = 16
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THEN
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SP := BP;
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ELSE (* StackAddrSize = 32 *)
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ESP := EBP;
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FI;
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IF OperandSize = 16
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THEN
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BP := Pop();
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ELSE (* OperandSize = 32 *)
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EBP := Pop();
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FI;
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</pre>
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<h2>Description</h2>
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LEAVE reverses the actions of the <a href="ENTER.HTM" tppabs="http://webster.cs.ucr.edu/Page_TechDocs/Doc386/ENTER.HTM">ENTER</a> instruction. By copying the frame pointer to the stack pointer, LEAVE releases the stack space used by a procedure for its local variables. The old frame pointer is popped into BP or EBP, restoring the caller's frame. A subsequent <a href="RET.HTM" tppabs="http://webster.cs.ucr.edu/Page_TechDocs/Doc386/RET.HTM">RET</a> instruction removes any arguments pushed onto the stack of the exiting procedure.
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<h2>Flags Affected</h2>
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None
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<h2>Protected Mode Exceptions</h2>
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#SS(0) if BP does not point to a location within the limits of the current stack segment
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<h2>Real Address Mode Exceptions</h2>
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Interrupt 13 if any part of the operand would lie outside of the effective address space from 0 to 0FFFFH
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<h2>Virtual 8086 Mode Exceptions</h2>
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Same exceptions as in Real Address Mode
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<p>
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<hr>
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<p><b>up:</b> <a href="C17.HTM" tppabs="http://webster.cs.ucr.edu/Page_TechDocs/Doc386/C17.HTM">Chapter 17 -- 80386 Instruction Set</a><br>
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<b>prev:</b><a href="LEA.HTM" tppabs="http://webster.cs.ucr.edu/Page_TechDocs/Doc386/LEA.HTM"> LEA Load Effective Address</a><br>
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<b>next:</b><a href="LGDT.HTM" tppabs="http://webster.cs.ucr.edu/Page_TechDocs/Doc386/LGDT.HTM"> LGDT/LIDT Load Global/Interrupt Descriptor Table Register</a>
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</body>
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