The control and memory unit of your CPU is in charge of processing the instructions that relate to flow control $($call$,$ ret, jmp$,$ j$*,$ cmp$,$ test$)$ and memory movements $($mov$*,$ push, pop$).$ In src$/$cmu$.$c$,$ you will implement the following functions $$ implement them in that order.

Call$/$ret $($note that the argument of the call instruction is relative to the current RIP, and indicates an $8-$byte signed displacement, i$.$e$.,$ if $*$A is $-10$ as a signed $8-$byte integer, then this call will remove $10$ from the RIP$).$

$/*$

$*$ Calls the function at address $*$A$.$ In practice, this:

$*-$ Pushes the current RIP $($cpu$\_$state$->$rip$)$ onto the stack, i$.$e$.,$ decrease RSP

$*($cpu$\_$state$->$regs$[$REG$\_$RSP$])$ by $8,$ then store the RIP at the address

$*$ indicated by RSP$.$

$*-\_$Add$\_$ the $8-$byte signed integer $*$A to the current RIP.

$*$

$*$ CORRESPONDING INSTRUCTION: call

$*/$

void op$\_$call $($cpu$\_$state$\_$t$*$ cpu$\_$state, uint$8\_$t$*$ a$)$

$/*$

$*$ Returns from a function. In practice, this:

$*-$ Sets the RIP to the $8-$byte integer at the top of the stack,

$*-$ Increase RSP by $8.$

$*$

$*$ CORRESPONDING INSTRUCTION: ret

$*/$

void op$\_$ret $($cpu$\_$state$\_$t$*$ cpu$\_$state$)$