$(25$ points$)$ The following codes run on the five$-$stage pipelined datapath. For each piece of code, answer

the following questions.

a$)$ Without forwarding, insert the necessary number of 'nops' for the code to execute correctly.

b$)$ With the forwarding unit available $($only supports forwards MEM $>$ EX and WB$>$EX$),$ show how

the code will execute. Mention the data that's forwarded between the stages. Use 'nops' only when

necessary.

Code $1$:

sub t$1,$ t$2,$ t$3$

add $t1,t4,t5$

or $t4,t2,t6$

Code $2$:

and $t2,t5,t1$

sub $t3,t2,t0$

nor t$7,$ t$1,$ t$5$

Code $3$:

and $t2,t5,t1$

sub t$3,$ t$2,$ to

nor t$7,$ t$2,$ t$1$

Code $4$:

lw $t1,22(t0)$

and $t2,t1,t3$

Code $5$:

lw t$1,22(t0)$

sub t$6,$ t$0,$ t$2$

xor $t3,t1,t5$