swap: sll $2, $5, 2 add $2, $4, $2 lw $15, 0($2) lw $16, 4($2) sw $16, 0($2) sw $15, 4($2)

This MIPS code performs a swap operation on a memory location pointed to by register $2. The values at the memory location are loaded into $15 and $16, then $16 is stored back at the beginning of the location and $15 is stored at the end of the location.

Here is a step-by-step breakdown of the code:

1. sll $2, $5, 2 - Shifts the value in register $5 left by 2 bits (multiplying by 4) and stores the result in $2.
2. add $2, $4, $2 - Adds the value in $4 to the value in $2 and stores the result back in $2.
3. lw $15, 0($2) - Loads the word at the memory location pointed to by the value in $2 into $15.
4. lw $16, 4($2) - Loads the word 4 bytes (1 word) after the location pointed to by the value in $2 into $16.
5. sw $16, 0($2) - Stores the value in $16 back at the beginning of the memory location pointed to by the value in $2.
6. sw $15, 4($2) - Stores the value in $15 at the end of the memory location pointed to by the value in $2.

Overall, this code swaps the values at the memory location pointed to by $2.