CPRE $381$ Homework $3($Fall $2024)$

$[$Note: This homework gives you more practice with the MIPS assembly language. When you are

asked to assemble a program, you can try running it on MARS to confirm it works. However,

make sure you have it running in Bare Machine configuration so that your machine code matches

the ISA.$]$

MIPS Machine Code

a$.$ The following instruction $($swap$)$ is not included in the MIPS instruction set:

$(15$pts$)$

swap $ to$,$ $t$1$

# The first operand is rs $,$ the second operand is it

# if $)$

# temp $=R[rs]$

# R$[$rs$]=$ R$[$rt$]$ # R$[$rt$]=$ temp

If this instruction were to be implemented in the MIPS instruction set, what is the

most appropriate instruction format? Explain why. Provide a sequence of MIPS

instructions that performs the same operation.

Postulate why this instruction wasn't included in

the MIPS ISA $($there is a general philosophical reason and at least one very

specific technical reason$).$