CopyRange:
  ; hl is source
  ; de is destination
  ; bc is length to copy
  ld a, b 
  or a, c
  ret z
.loop
  ld a, [hl+]
  ld [de], a
  inc de
  dec bc
  ld a, b
  or a, c ; check if bc is zero
  jr nz, .loop
  
  ret

CopyRangeBy8s:
  ; hl is source
  ; de is destination
  ; bc is length to copy
  ld a, b 
  or a, c
  ret z
.loop
  rept 8
    ld a, [hl+]
    ld [de], a
    inc de
    dec bc
  endr
  ld a, b
  or a, c ; check if bc is zero
  jr nz, .loop
  
  ret

CopyOneTileData:
  di
  rept 16
    ld a, [hl+]
    ld [de], a 
    inc de
  endr
  reti