auto VDP::Background::scanline() -> void {
}

auto VDP::Background::run(uint x, uint y) -> void {
  output.priority = 0;
  output.color = 0;

  uint tileX = x >> 3;
  uint tileY = y >> 3;
  uint15 nametableAddress = io.nametableAddress;
  nametableAddress += (tileY << io.nametableWidth) + tileX;

  uint16 tileAttributes = vdp.vram[nametableAddress];
  uint15 tileAddress = tileAttributes.bits(0,10) << 4;
  uint pixelX = (x & 7) ^ (tileAttributes.bit(11) ? 7 : 0);
  uint pixelY = (y & 7) ^ (tileAttributes.bit(12) ? 7 : 0);
  tileAddress += pixelY << 1 | pixelX >> 2;

  uint16 tileData = vdp.vram[tileAddress];
  uint4 palette = tileData >> (((pixelX & 3) ^ 3) << 2);
  if(palette) {
    output.color = tileAttributes.bits(13,14) << 4 | palette;
    output.priority = tileAttributes.bit(15);
  }
}

auto VDP::Background::power() -> void {
}

auto VDP::Background::reset() -> void {
  memory::fill(&io, sizeof(IO));
}