 :-        ; pos>=0 -> next        
  rts


; -------------------------------------
; set line vectors
;
; line no in X
; destroys A and Y
;
; sets start of screen line in temp_ptr_x
; sets start of colour line in temp_ptr_y
; -------------------------------------

set_line_vectors:
  lda $ecf0,x   ; get lo byte
  sta temp_ptr_x
  sta temp_ptr_y
  ; determin hi byte
  ldy #$04      ; hi byte
  cpx #$07      ; line < 7?
  bcc @got_line_vector
  iny           
  cpx #$0d      ; line < 1