; Z https://en.wikipedia.org/wiki/Extended_Euclidean_algorithm#Pseudocode
bezout:                 ; (old_r, r) := (a, b)  # l1, l2
    put  1 -> l3        ; (old_s, s) := (1, 0)  # l3, l4
    put  0 -> l4
    put  0 -> l5        ; (old_t, t) := (0, 1)  # l5, l6
    put  1 -> l6
loop:
    jz   l2, done       ; while r ≠ 0 do
    sdiv l1, l2 -> l7   ;   quotient := old_r div r # l7
    copy l2     -> t1   ;   (old_r, r) := (r, old_r − quotient × r)
    mul  l2, l7 -> l2
    sub  l1, l2 -> l2
    copy t1     -> l1
    copy l4     -> t1   ;   (old_s, s) := (s, old_s − quotient × s)
    mul  l4, l7 -> l4
    sub  l3, l4 -> l4
    copy t1     -> l3
    copy l6     -> t1   ;   (old_t, t) := (t, old_t − quotient × t)
    mul  l6, l7 -> l6
    sub  l5, l6 -> l6
    copy t1     -> l5
    jmp  loop
done:
    copy l3 -> rv
    copy l5 -> l1
    ret