up: Chapter 17 -- 80386 Instruction Set
prev: PUSH Push Operand onto the Stack
next: PUSHF/PUSHFD Push Flags Register onto the Stack

PUSHA/PUSHAD -- Push all General Registers

Opcode  Instruction  Clocks   Description

60      PUSHA        18       Push AX, CX, DX, BX, original SP, BP, SI, and
                              DI
60      PUSHAD       18       Push EAX, ECX, EDX, EBX, original ESP, EBP,
                              ESI, and EDI

Operation

IF OperandSize = 16 (* PUSHA instruction *)
THEN
   Temp := (SP);
   Push(AX);
   Push(CX);
   Push(DX);
   Push(BX);
   Push(Temp);
   Push(BP);
   Push(SI);
   Push(DI);
ELSE (* OperandSize = 32, PUSHAD instruction *)
   Temp := (ESP);
   Push(EAX);
   Push(ECX);
   Push(EDX);
   Push(EBX);
   Push(Temp);
   Push(EBP);
   Push(ESI);
   Push(EDI);
FI;

Description

PUSHA and PUSHAD save the 16-bit or 32-bit general registers, respectively, on the 80386 stack. PUSHA decrements the stack pointer (SP) by 16 to hold the eight word values. PUSHAD decrements the stack pointer (ESP) by 32 to hold the eight doubleword values. Because the registers are pushed onto the stack in the order in which they were given, they appear in the 16 or 32 new stack bytes in reverse order. The last register pushed is DI or EDI.

Flags Affected

None

Protected Mode Exceptions

#SS(0) if the starting or ending stack address is outside the stack segment limit; #PF(fault-code) for a page fault

Real Address Mode Exceptions

Before executing PUSHA or PUSHAD, the 80386 shuts down if SP or ESP equals 1, 3, or 5; if SP or ESP equals 7, 9, 11, 13, or 15, exception 13 occurs

Virtual 8086 Mode Exceptions

Same exceptions as in real-address mode; #PF(fault-code) for a page fault

up: Chapter 17 -- 80386 Instruction Set
prev: PUSH Push Operand onto the Stack
next: PUSHF/PUSHFD Push Flags Register onto the Stack