struct Cache {
  uint8* tiledata[3];
  uint8* tilevalid[3];

  uint8* tile_2bpp(unsigned tile);
  uint8* tile_4bpp(unsigned tile);
  uint8* tile_8bpp(unsigned tile);
  uint8* tile(unsigned bpp, unsigned tile);

  void serialize(serializer&);
  Cache(PPU& self);

  PPU& self;
  friend class PPU;
};