(
    (main
        (call fac 5)
        (ld r0 res0)
        (halt)
    )
    (fac
        (cmp arg0 2
            (eq? (ret 2)))
        (sub r0 arg0 1)
        (call fac r0)
        (mul r0 arg0 res0)
        (ret r0)
    )
)