Assembly: 

SUB rd, rs, rt

nanoMIPS, not available in NMS

Subtract

Purpose:

Subtract. Subtract the 32-bit signed integer in register $rt from the 32-bit signed integerin register $rs, placing the 32-bit result in register $rd, and trapping on overflow.

Availability:

nanoMIPS, not available in NMS

Format:

001000

rt

rs

rd

x

0110010

000

6

5

5

5

1

7

3

Operation: 

if C0.Config5.NMS == 1:
    raise exception('RI')
result = GPR[rs] -GPR[rt]
if overflows(result, nbits=32):
    raise exception('OV')
GPR[rd] = sign_extend(result, from_nbits=32)

Exceptions:

None.