Pseudoinstructions: Set

Instruction

Real instructions

Semantics

Set if equal:

seq $rd, $rs, $rt

andi $rd, $rd, 0

#

R[d] = (R[s] == R[t]) ? 1 : 0

bne $rs, $rt, next

ori $rd, $zero, 1

next:

What's wrong with this?

Better way:

xor $rd, $rs, $rt

#

R[d] = ~(R[s] == R[t])

sltiu $rd, $rd, 1

#

R[d] = (R[d] < 1)

Set if not equal:

sne $rd, $rs, $rt

#

R[d] = (R[s] != R[t]) ? 1 : 0

xor $rd, $rs, $rt

#

R[d] = ~(R[s] == R[t])

sltu $rd, $0, $rd

#

R[d] = (R[d] > 0)

Set if greater than or equal:

sge $rd, $rs, $rt

#

R[d] = (R[s] >= R[t]) ? 1 : 0

slt $rd, $rs, $rt

#

R[d] = (R[s] < R[t]) ? 1 : 0

xori $rd, $rd, 1

#

R[d] = ~R[d]

Other combinations, including unsigned:

sgeu, sgt, sgtu, sle, sleu