Insymbol Section $(1$ entry$)$

result $10$

Outsymbol Section $(2$ entries$)$

get$425$

get$423$

Object Code $(11$ words$)$

export answer

jmp mainx $20$

answer:

word $10$

lock:

word $0$

main $20$ :

Idimm r$5,100$

Idimm r$4,0$ # loop counter

Idimm r$6,1$ #loop counter increment

Idimm r$7,5$ # upper bound

doitagain:

# busy wait on the lock

Idimm $r1,1$ # want to set the lock to $1$

tryAgain:

Idimm r$2,0$ # need to wait until lock is $0$

cmpxchg $r2,r1,$ lock # if lock is $0$ then lock it

beq $r2,r1,$ tryAgain # else $r2$ will be set to $1,$ and if so repeat

load ro$,$ answer # now have exclusive control

addi $r0,r5$ # so safe to add in the local answer

store $r0,$ answer

Idimm $r2,0$ # unlock

store $r2,$ lock

addi $r4,r6$

blt $r4,r7,$ doitagain

# all done!

halt