APPENDIX A MIPS III INSTRUCTION SET DETAILS
482 Preliminary Users Manual S15543EJ1V0UM
DMULT Doubleword Multiply DMULT
rs
SPECIAL
0 0 0 0 0 0 rt 0
0 0 0 0 0 0 0 0 0 0
31 26 25 21 20 16 15 0
655 10

DMULT

0 1 1 1 0 0

65
6
Format:
DMULT rs, rt
Description:
The contents of general registers
rs
and
rt
are multiplied, treating both operands as 2s complement values. No
integer overflow exception occurs under any circumstances.
When the operation completes, the low-order word of the double result is loaded into special register
LO
, and the
high-order word of the double result is loaded into special register
HI
.
If either of the two preceding instructions is MFHI or MFLO, the results of these instructions are undefined. Correct
operation requires separating reads of
HI
or
LO
from writes by a minimum of two other instructions.
This operation is defined in 64-bit mode or in 32-bit kernel mode. Execution of this instruction in 32-bit user or
supervisor mode causes a reserved instruction exception.
Operation:
64 T-2: LO undefined
HI undefined
T-1: LO undefined
HI undefined
T: t GPR [rs] * GPR [rt]
LO t63..0
HI t127..64
Exceptions:
Reserved instruction exception (32-bit user mode/supervisor mode)