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LEAVE -- High Level Procedure Exit




Opcode  Instruction  Clocks  Description

C9      LEAVE        4       Set SP to BP, then pop BP
C9      LEAVE        4       Set ESP to EBP, then pop EBP

Operation




IF StackAddrSize = 16
THEN
   SP := BP;
ELSE (* StackAddrSize = 32 *)
   ESP := EBP;
FI;
IF OperandSize = 16
THEN
   BP := Pop();
ELSE (* OperandSize = 32 *)
   EBP := Pop();
FI;

Description

LEAVE reverses the actions of the ENTER 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 RET instruction removes any arguments pushed onto the stack of the exiting procedure.

Flags Affected

None

Protected Mode Exceptions

#SS(0) if BP does not point to a location within the limits of the current stack segment

Real Address Mode Exceptions

Interrupt 13 if any part of the operand would lie outside of the effective address space from 0 to 0FFFFH

Virtual 8086 Mode Exceptions

Same exceptions as in Real Address Mode

up: Chapter 17 -- 80386 Instruction Set
prev: LEA Load Effective Address
next: LGDT/LIDT Load Global/Interrupt Descriptor Table Register