Instruction Set
4-76
IRET
Interrupt Return
IRET
What It Does
IRET ends an interrupt handler and resumes the interrupted procedure.
Syntax
Description
Used at the end of an interrupt handler, IRET restores the Instruction Pointer (IP) register,
the Code Segment (CS) register, and the Processor Status Flags (FLAGS) register from
the stack, and then resumes the interrupted procedure.
Operation It Performs
Flag Settings After Instruction
Form
Opcode
Description
Clocks
Am186 Am188
IRET
CF
Return from interrupt handler to interrupted procedure
28
28
IRET
/* restore address of next instruction */
IP = pop();
CS = pop();
/* restore flags */
FLAGS = pop();
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
Restores value of FLAGS register that was stored
on the stack when the interrupt was taken.
res
res
res
Summary of Contents for Am186 Series
Page 1: ...Am186 and Am188 Family Instruction Set Manual February 1997...
Page 10: ...Table of Contents x...
Page 18: ...Programming 1 8...
Page 40: ...Instruction Set Listing 3 14...