Using GBZ80 to do mod 24 using Chinese Remainder Theorem

a_mod_3:
.loop
    sub 3
    jr c, .loop
    add 3
    ret

dehl_mod_3:
    push bc
    ld b, 0
    ld a, d
    call a_mod_3
    ld b, a
    ld a, e
    call a_mod_3
    add b
    ld b, a
    ld a, h
    call a_mod_3
    add b
    ld b, a
    ld a, l
    call a_mod_3
    add b
    pop bc
    cp 3
    ret c
    call a_mod_3
    ret

dehl_mod_24:
    push bc
    ld a, l
    and 7
    ld b, a
    srl
    srl
    srl
    add b
    ld b, a
    call dehl_mod_3
    srl
    srl
    srl
    cpl
    add b
    pop bc
    ret