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

    allocate-registers a                 ; input/output
    allocate-registers b                 ; input
    allocate-registers bzero, gcd, testb ; labels
    allocate-registers zero              ; constant
    allocate-registers newb, test        ; temporary

    li zero 0
    li testb Ltestb
    li gcd Lgcd
    li bzero Lbzero

    read a
    read b

    slt test a zero
    jeqz test testb
    sub a zero a

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

Lgcd:
    jeqz b bzero
    rem newb a b
    add a b zero
    add b newb zero
    j gcd

Lbzero:
    write a
    halt