(
    (proc itoa buf num
        (ld r1 num)
        (tst r1 (<0? (mul r1 -1)))
        (:next)
            (mod r0 r1 10)
            (add r0 '0')
            (bfrpush @buf r0)
            (div r1 10 (z?
                (tst num (<0? (bfrpush @buf '-')))
                (ret)))
            (j :next)
    )
)