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80386 Programmer's Reference Manual -- Opcode POPA

POPA/POPAD -- Pop all General Registers

Opcode	Instruction	Clocks	Description	Example
61	popa	24	Pop DI, SI, BP, SP, BX, DX, CX, and AX	`popa`
61	popal	24	Pop EDI, ESI, EBP, ESP, EDX, ECX, and EAX	`popal`

Operation




IF OperandSize = 16 (* instruction = POPA *)
THEN
   DI := Pop();
   SI := Pop();
   BP := Pop();
   throwaway := Pop (); (* Skip SP *)
   BX := Pop();
   DX := Pop();
   CX := Pop();
   AX := Pop();
ELSE (* OperandSize = 32, instruction = POPAD *)
   EDI := Pop();
   ESI := Pop();
   EBP := Pop();
   throwaway := Pop (); (* Skip ESP *)
   EBX := Pop();
   EDX := Pop();
   ECX := Pop();
   EAX := Pop();
FI;

Description

POPA pops the eight 16-bit general registers. However, the SP value is discarded instead of loaded into SP. POPA reverses a previous PUSHA, restoring the general registers to their values before PUSHA was executed. The first register popped is DI.

POPAD pops the eight 32-bit general registers. The ESP value is discarded instead of loaded into ESP. POPAD reverses the previous PUSHAD, restoring the general registers to their values before PUSHAD was executed. The first register popped is EDI.

Flags Affected

None

Protected Mode Exceptions

#SS(0) if the starting or ending stack address is not within the stack segment; #PF(fault-code) for a page fault

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; #PF(fault-code) for a page fault

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