//------------------------------------------------------------------------
// Title       : game.v
// Descrition : This module implements the FSM for the reaction game.
//              It only has one player and must be extended to two.
//---------------------------------------------------------------------------

`timescale 1ns / 1ns

module game (clk, reset, startButton, loadCnt, tc, startLight, 
	     stopA, winA, stopB, winB);
   input clk, reset;
   input startButton;	// Button to start the game
   output loadCnt;      // Load the counter
   output startLight;   // Turn on the start light
   input tc;			// Terminal count from counter
   input  stopA, stopB; // Player stop buttons
   output winA, winB;   // Player Win lights

   // Reg declarations for always block assignments
   reg loadCnt;      
   reg startLight;   
   reg 	  winA, winB;
   
   // State encoding
   parameter IDLE=0,    // Reset state
	     START=1,   // Start the game
	     WAIT=2,    // Wait for stop button
	     AWIN=3;    // Player A wins!
   
   // The state register
   reg [1:0] state, nxt_state;
   
   // This block implements a simple state register
   always @(posedge clk) begin
      if (reset) state <= IDLE;
      else       state <= nxt_state;
   end

   // This block implements the next state function
   // and the output function
   always @(state or startButton or tc) begin
      // Defaults
      loadCnt = 0;
      startLight = 0;
      winA = 0;
      winB = 0;
      case (state) 
	// Reset state
	IDLE: begin
	   if (startButton) begin
	      loadCnt = 1;
	      nxt_state = START;
	   end else begin
	      nxt_state = IDLE;
	   end
	end
	// Counter has been loaded; wait for it to finish
	START: begin
	   if (tc) nxt_state = WAIT;
	   else nxt_state = START;
	end
	// Counter has finished, turn on the start light and
	// wait for stop button
	WAIT: begin
	   startLight = 1;
	   if (stopA) nxt_state = AWIN;
	   else nxt_state = WAIT;
	end
	// Stop button has been pushed; turn on win light
	AWIN: begin
	   winA = 1;
	   if (startButton) begin
	      nxt_state = START;
	      loadCnt = 1;
	   end else begin
	      nxt_state = AWIN;
	   end
	end
      endcase // case(state)
   end // always @ (*)
endmodule // count8