;; Read in two integers a, b and print out their gcd,
;; like in the following python script:
;;
;; a = input()
;; b = input()
;; print gcd(a, b)
;;
;; def gcd(a, b):
;;     if a < 0: a = -a
;;     if b < 0: b = -b
;;     while b > 0:
;;         a, b = b, a % b
;;     return a

    allocate-registers a                 ; input, output
    allocate-registers b                 ; input
    allocate-registers cont              ; continuation register
    allocate-registers gcd, testb, loop  ; labels
    allocate-registers zero              ; constant
    allocate-registers newb, test        ; temporary

    li zero 0
    li testb Ltestb
    li gcd Lgcd
    li loop Lloop
    li cont Ldone

    read a
    read b
    j gcd
Ldone:
    write a
    halt  

;;;;;;;;;; gcd starts here
Lgcd:
    slt test a zero
    jeqz test testb
    sub a zero a

Ltestb:
    slt test b zero
    jeqz test loop
    sub b zero b

Lloop:
    jeqz b cont
    rem newb a b
    add a b zero
    add b newb zero
    j loop