Subtract – NEC Network Controller uPD98502 User Manual
Page 558
APPENDIX A MIPS III INSTRUCTION SET DETAILS
558
Preliminary User’s Manual S15543EJ1V0UM
SUB
Subtract
SUB
rs
SPECIAL
0 0 0 0 0 0
rt
rd
0
0 0 0 0 0
SUB
1 0 0 0 1 0
31
26 25
21 20
16 15
11 10
6 5
0
6
5
5
5
5
6
Format:
SUB rd, rs, rt
Description:
The contents of general register
rt are subtracted from the contents of general register rs to form a result. The
result is placed into general register
rd. In 64-bit mode, the operands must be valid sign-extended, 32-bit values.
The only difference between this instruction and the SUBU instruction is that SUBU never traps on overflow.
An integer overflow exception takes place if the carries out of bits 30 and 31 differ (2's complement overflow). The
destination register
rd is not modified when an integer overflow exception occurs.
Operation:
32
T:
GPR [rd]
← GPR [rs] - GPR [rt]
64
T:
temp
← GPR [rs] - GPR [rt]
GPR [rd]
← (temp
31
)
32
|| temp
31...0
Exceptions:
Integer overflow exception