1. MIPS Assembly

2. Questions Is it correct to write this instruction?
add $s0, $s1, $s2, $s3
No. Can only take two for add, produce one

3. Questions Is it correct to write this instruction? add $s0, $s0, $s0
Yes

4. Questions How to use only one instruction to set $t0 to 0?
Add $t0, $0, $0

5. Questions Is it correct to write this instruction? lw $s0, 100($s0)
Yes

6. Questions Is it correct to write this instruction? lw $s0, $s1($s0)
No. The number must be a constant

7. Questions Is it correct to write this instruction?
add $s0, 100($s1), $s2
No. The two numbers to be added must be registers, not from memory

8. Questions
Suppose memory at address 1000 to 1028 are storing 1,2,…,8 (in each 4 bytes). Suppose $t0 is What will be in $t0 after this instruction?
lw $t0, 16($t0) 5

9. Exercise
Suppose we have the address of A[i] in $t0, where A is an integer array. Write instructions to swap A[i] and A[i+1].
lw $t1, 0(t0)
lw $t2, 4(t0)
sw $t2, 0(t0)
sw $t1, 4(t0)

10. Processor
Memory
Address t1
100
Assume the values are 100 and 101
100 t0 t2
xxxxxxxxxx
101
t0+4
lw $t1, 0(t0)
lw $t2, 4(t0)
sw $t2, 0(t0)
sw $t1, 4(t0) t1
100
100 t0 t2
101
101
t0+4 t1
100
101 t0 t2
101
101
t0+4 t1
100
101 t0 t2
101
100
t0+4