Flags affected:

        O D I T S Z A P C  OF: Overflow flag  TF: Trap flag AF: Aux carry
        F F F F F F F F F  DF: Direction flag SF: Sign flag PF: Parity flag
        * * * * * * * * *  IF: Interrupt flag ZF: Zero flag CF: Carry flag

Legal forms:

        POPFD <none>

Examples:

        POPFD

Notes:

POPFD pops the double word (4 bytes) at the top of the stack into the EFlags register. In 32-bit protected mode, the top of the stack is defined as the DWORD at [ESP], and there is no way to override the SS segment with prefixes.

ESP is incremented by 4 after the word comes off the stack. Remember that ESP always points to either an empty stack or else real data. There is a separate pair of instructions, PUSH and POP, for pushing and popping other register data and memory data, in both 16-bit and 32-bit sizes.

PUSHFD and POPFD are most used in writing 32-bit interrupt service routines, where you must be able to save and restore the environment, that is, all machine registers, to avoid disrupting machine operations while servicing the interrupt.

        r8 = AL AH BL BH CL CH DL DH        r16 = AX BX CX DX BP SP SI DI
        sr = CS DS SS ES FS GS              r32 = EAX EBX ECX EDX EBP ESP ESI EDI
        m8 = 8-bit memory data              m16 = 16-bit memory data
        m32 = 32-bit memory data            i8 = 8-bit immediate data
        i16 = 16-bit immediate data         i32 = 32-bit immediate data
        d8 = 8-bit signed displacement      d16 = 16-bit signed displacement
        d32 = 32-bit unsigned displacement