text: #ifndef GAME_H
  #define GAME_H
  
  /***********************************************************************
   * Game constants.
   */
  
  // Range a paddle may move (y direction)
  #define PADDLE_MINY  66 << 4
  #define PADDLE_MAXY 200 << 4
  
  // Initial paddle positions
  #define PADDLE_INITIAL_Y            130 << 4
  #define PADDLE_LEFT_INITIAL_X       24
  #define PADDLE_LEFT_INITIAL_X_HI    0
  #define PADDLE_RIGHT_INITIAL_X      334
  #define PADDLE_RIGHT_INITIAL_X_HI   1
  
  // Paddle y move speed
  #define PADDLE_DY 8
  
  // Range the ball may move (y direction)
  // - BALL_MAXY differs from PADDLY_MAXY because the paddle is taller
  #define BALL_MINY  66 << 4
  #define BALL_MAXY 232 << 4
  
  // Range the ball may move (x direction)
  #define BALL_MINX 24 << 4
  #define BALL_MAXX 335 << 4
  
  // Initial ball position
  #define BALL_INITIAL_X 180 << 4
  #define BALL_INITIAL_Y 146 << 4
  
  // Number of points to win a game
  #define POINTS_TO_WIN 10
  
  // An inverse whitespace
  #define BLANK_INVERSE_BLOCK 32+128
  
  // Maximum delta-y of the ball
  #define BALL_DY_MIN -8
  #define BALL_DY_MAX  8
  
  // Delta-x move speed of the ball.
  #define BALL_DX 8
  
  
  /***********************************************************************
   * Structures
   */
  
  enum {
      HUMAN = 0,
      WALL,
  };
  
  struct Player
  {
      unsigned char points;
      unsigned short y;
      unsigned char type; // HUMAN|CPU|WALL
  };
  
  struct Ball
  {
      // large (16 times the real values, because we are missing floating point operations)
      unsigned short x, y;
      signed short dx, dy;
  };
  
  
  /***********************************************************************
   * Globals
   */
  
  extern struct Player player1;
  extern struct Player player2;
  
  
  /***********************************************************************
   * Procedures
   */
  
  void play_game();
  
  void init_sprites();
  
  void wait_any_fire();
  
  void show_sprites();
  
  void hide_sprites();
  
  
  
  #endif // GAME_H
  