vars
  U[8] buf      // A buffer that can store the current and next row
  U row_a = 0   // We swap back and forth between these two offsets for each row
  U row_b = 4
  UU drawing_row_offset = 0// Use this to track which row we're drawing
  U current_rule = %00011110
  U next_cell = 0

fn init_screen()
  ppu_reset_addr($2000)

  // Set background tiles
  for UU i = 0; i < 960; i += 1
    {PPUDATA}(1)

  U i = 0
  // Set attributes for background
  for i = 0; i < 64; i+= 1
    {PPUDATA}(%00011011)

  // Init the buffers to 0
  for i = 0; i < 8; i += 1
    buf[i] = 0

fn calc_and_upload_next_row()
  // "scroll" to the row we're at
  UU row_start = $2000
  row_start += (drawing_row_offset * 32)
  ppu_reset_addr(row_start)

  for UU i = 0; i < 32; i += 1
    //next_cell = 0 //get_next_gen(i)
    {PPUDATA}(next_cell)

  drawing_row_offset += 1

  if drawing_row_offset == 30
    drawing_row_offset = 0
    if next_cell
      next_cell = 0
    else
      next_cell = 1

nmi main_nmi()
  ppu_upload_oam_poll_pads(0)

  calc_and_upload_next_row()

  // Turn on rendering sprites and bg
  {PPUMASK}(PPUMASK_ON | PPUMASK_NO_CLIP)

  ppu_reset_scroll(0, 0)


mode main()
: nmi main_nmi
  // Set the palette:
  palette = example_palette
  ppu_upload_palette()

  // Load the background
  init_screen()

  // Turn the NMI on
  {PPUCTRL}(PPUCTRL_NMI_ON)

  // Loop forever:
  while true
    update_pads()
    nmi

// Define the tileset (commonly called CHR):
chrrom
  file(fmt, "tiles.png")