$s0 = pow, $s1 = x

addi $s0, $0, 1
add $s1, $0, $0
addi $t0, $0, 128
while: beq $s0, $t0, L1
j done
L1:
sll $s0, $s0, 1
addi $s1, $s1, 1
j while
done: