More efficient CopyData function

CopyData::
    ld a, e
    add c
    jr c, .noOverflow
    dec b
.noOverflow
    inc b
    jr z, .loop2
    and a
    ld c, a
    jr z, .handleLoop
.loop1
    ld a, [hli]
    ld [de], a
    inc e
    jr nz, .loop1
    inc d
.handleLoop
    dec b
    jr nz, .loop1
.loop2
    ld a, [hli]
    ld [de], a
    inc e
    dec c
    jr nz, .loop2
    ret