Divide24: //r22r23r24 = r19r20r21 / r16r17r18;   % in r19r20r21
    ldi     r22,0
    ldi     r23,0
    ldi     r24,0
F1div:
    cp      r19,r16
    cpc     r20,r17
    cpc     r21,r18
    brcs    F1done
    sub     r19,r16
    sbc     r20,r17
    sbc     r21,r18
    inc     r22
    brne    F1div
    inc     r23
    brne    F1div
    inc     r24
    rjmp    F1div
F1done:
    ret