Dmacc, Doubleword multiply and accumulate (3/3) – NEC Network Controller uPD98502 User Manual
Page 479
APPENDIX A MIPS III INSTRUCTION SET DETAILS
Preliminary User’s Manual S15543EJ1V0UM
479
DMACC
Doubleword Multiply and Accumulate (3/3)
DMACC
Operation:
64, sat=0, us=0 (DMACC instruction)
T:
temp1
← ((GPR[rs]
31
)
32
|| GPR [rs]) * ((GPR[rt]
31
)
32
|| GPR [rt])
temp2
← temp1 + LO
LO
← temp2
GPR[rd]
← LO
64, sat=0, us=1 (DMACCU instruction)
T:
temp1
← (0
32
|| GPR [rs]) * (0
32
|| GPR [rt])
temp2
← temp1 + LO
LO
← temp2
GPR[rd]
← LO
64, sat=1, us=0 (DMACCS instruction)
T:
temp1
← ((GPR[rs]
31
)
32
|| GPR [rs]) * ((GPR[rt]
31
)
32
|| GPR [rt])
temp2
← saturation(temp1 + LO)
LO
← temp2
GPR[rd]
← LO
64, sat=1, us=1 (DMACCUS instruction)
T:
temp1
← (0
32
|| GPR [rs]) * (0
32
|| GPR [rt])
temp2
← saturation(temp1 + LO)
LO
← temp2
GPR[rd]
← LO
Exceptions:
Reserved instruction exception (32-bit user mode/supervisor mode)