AMD Am186 Series, Instruction Set

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Instruction Set 4-186
PUSHF Push Flags onto Stack PUSHF
What It Does
PUSHF creates storage space for a component on the stack and then copies the Processor
Status Flags (FLAGS) register to the stack.
Syntax
Description
PUSHF decrements the stack pointer by 2 and copies the FLAGS register to the new top
of stack.
Operation It Performs
Flag Settings After Instruction
Tips
Before you use PUSHF, use MOV to copy the stack segment to SS and the stack offset to
SP.
To prevent an instruction or a called procedure from modifying flags that are necessary for
the successful execution of the following instructions or calling procedure, use PUSHF to
save the Processor Status Flags register. After the instruction or the procedure call, use
POPF to restore the saved flags.
Related Instructions
Form Opcode Description
Clocks
Am186 Am188
PUSHF 9C Push Processor Status Flags register 9 13
If you want to See
Copy the low byte of the Processor Status Flags register to AH LAHF
Pop a component from the stack into the Processor Status Flags register POPF
Push a component onto the stack PUSH
Push the 16-bit general registers onto the stack PUSHA
PUSHF
/* create storage on stack */
SP = SP - 2;
/copy flags to stack */
SS:[SP] = FLAGS;
15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0
Processor Status
Flags Register
reserved
OF DF IF TF SF ZF AF PF CF
? = undefined; – = unchanged
– – – – – – res – res – res –