module chip8 (
    input wire clk_in,
    input wire rst_in
);

  bit vram[0:2047];
  bit [7:0] memory[0:4095];

  bit keyboard[15:0];

  bit [7:0] sound_timer;
  bit [15:0] program_counter;
  int cycle_counter;

  bit rom_ready;
  bit font_ready;
  bit system_ready;
  bit halt;

  bit [7:0] random_number;

  and(system_ready, rom_ready, font_ready);

  beeper beeper (sound_timer);
  cpu cpu (
      system_ready,
      memory,
      clk_in,
      keyboard,
      random_number,
      cycle_counter,
      program_counter,
      vram,
      sound_timer 
  );
  gpu gpu (vram);
  keyboard kb (
      clk_in,
      keyboard
  );
  rng randy (
      clk_in,
      program_counter,
      keyboard,
      cycle_counter,
      random_number
  );
  rom_loader loader (clk_in, rst_in, memory, rom_ready);

  always_ff @(negedge clk_in) begin
    if (~font_ready) begin
        bit [7:0] fontset[79:0] = {
          8'hF0,
          8'h90,
          8'h90,
          8'h90,
          8'hF0,  // 0
          8'h20,
          8'h60,
          8'h20,
          8'h20,
          8'h70,  // 1
          8'hF0,
          8'h10,
          8'hF0,
          8'h80,
          8'hF0,  // 2
          8'hF0,
          8'h10,
          8'hF0,
          8'h10,
          8'hF0,  // 3
          8'h90,
          8'h90,
          8'hF0,
          8'h10,
          8'h10,  // 4
          8'hF0,
          8'h80,
          8'hF0,
          8'h10,
          8'hF0,  // 5
          8'hF0,
          8'h80,
          8'hF0,
          8'h90,
          8'hF0,  // 6
          8'hF0,
          8'h10,
          8'h20,
          8'h40,
          8'h40,  // 7
          8'hF0,
          8'h90,
          8'hF0,
          8'h90,
          8'hF0,  // 8
          8'hF0,
          8'h90,
          8'hF0,
          8'h10,
          8'hF0,  // 9
          8'hF0,
          8'h90,
          8'hF0,
          8'h90,
          8'h90,  // A
          8'hE0,
          8'h90,
          8'hE0,
          8'h90,
          8'hE0,  // B
          8'hF0,
          8'h80,
          8'h80,
          8'h80,
          8'hF0,  // C
          8'hE0,
          8'h90,
          8'h90,
          8'h90,
          8'hE0,  // D
          8'hF0,
          8'h80,
          8'hF0,
          8'h80,
          8'hF0,  // E
          8'hF0,
          8'h80,
          8'hF0,
          8'h80,
          8'h80  // F
        };
    
        // Load fontset into memory
        for (int i = 0; i < 80; i++) begin
          memory[i] = fontset[79-i];
        end

        font_ready = 1;
    end
  end
endmodule