|
| |
Interrupt on Overflow
|
86/88 |
Y |
186 |
Y |
286 |
Y |
386 |
Y |
486 |
Y |
INTO |
|
Ovfl |
N |
Dir |
N |
Int |
0 |
Trap |
0 |
Sign |
N |
Zero |
N |
Aux |
N |
Prty |
N |
Carry |
N |
INTO activates interrupt type 4 if the Overflow Flag is set; otherwise
it does nothing. This interrupt operates identically to an "INT 4" if
the overflow flag is set, in which case INTO pushes the flags
register, clears the Trap and Interrupt-enable Flags, pushes CS and
IP, then transfers control to the interrupt-num 4 handler, which is
pointed to by the vector at location 10h. If the interrupt handler
returns using an IRET instruction, the original flags are restored.
Notes: The flags are stored in the same format as that used
by the PUSHF instruction.
INTO can be used after an operation that may cause
overflow, to call a recovery procedure.
------------------------------------ Timing ----------------------------------
OpCode Instruction 386 286 86
CE INTO 3/35 3/24 4/53
Protected mode, same priveledge 59 41
Protected mode, more priveledge 99 79
Protected mode, V86 to PLO 119
Protected mode, via task gate ts 168
------------------------------------ Logic -----------------------------------
If (OF = 1) then
PUSHF
TF = 0
IF = 0
CALL FAR (10h)
See Also INT IRET JNO JO PUSHF CALL INT/04 Flags |