; Set log level to "info" or above for the best results!
(
    (sc-init 800 600)
    (sc-opt SCREEN_AUTO_BLIT 1)
    (sc-opt SCREEN_FPS 25)

    (sym x r0) (sym y r1) (sym dx r2) (sym dy r3) (sym color r5)

    (ld x 5) (ld y 0)
    (ld dx 1) (ld dy 1)
    (ld color 0x3300ff)

    (:loop)
        (add color 0x000001)
        (sc-px x y color)

        (add x dx (z? (ld dx 1)))
        (cmp x 799 (eq? (ld dx -1)))

        (add y dy (z? (ld dy 1)))
        (cmp y 599 (eq? (ld dy -1)))
    (j :loop)
)