test_drink.v

Systemverilog 编写的贩卖机代码

`timescale 1ns / 1ns

module test_drink;


wire  dime_out, dispense, empty, nickel_dime_out, nickel_out, two_dime_out;
     


reg  clk, nickel_in, dime_in, quarter_in, load, reset;



reg  [7:0] r_cans, r_nickels, r_dimes;
wire [7:0] cans, nickels, dimes;



drink_machine_top top(
	.clk(clk),.nickel_in(nickel_in), .dime_in(dime_in), 
	.quarter_in(quarter_in), .load(load),  .reset(reset),
	.cans(r_cans), .nickels(r_nickels), .dimes(r_dimes),
	.nickel_out(nickel_out), .dime_out(dime_out), 
	.two_dime_out(two_dime_out), .dispense(dispense), 
	.empty(empty), .exact_change(exact_change)
); 
 

	initial
		begin : generate_clock
			clk <= 0;
			forever #100 clk <= ~clk;
		end

	initial
		begin : initialize_machine
			        nickel_in  <= 0;
			        dime_in    <= 0;
			        quarter_in <= 0;
			        load       <= 0;
			     	reset      <= 1;
			#200	reset      <= 0;
			        r_cans       <= 5;
				r_nickels    <= 20;
				r_dimes      <= 15;
			        load_machine;
					repeat (10) buy_drinks;
				$finish;
		end

	task buy_drinks;
		begin
			enter_nickel;
			enter_dime;
			enter_quarter;
			enter_dime;
			enter_quarter;
			enter_nickel;
			enter_nickel;
			enter_dime;
			enter_dime;
			enter_quarter;
			enter_nickel;
			enter_dime;
			enter_quarter;
			enter_dime;
			enter_quarter;
			enter_nickel;
			enter_nickel;
			enter_dime;
			enter_dime;
			enter_quarter;
			enter_quarter;
			enter_nickel;
			enter_dime;
			enter_quarter;
			enter_dime;
			enter_quarter;
			enter_nickel;
			enter_nickel;
			enter_dime;
			enter_dime;
		end
	endtask

	task load_machine;
		begin
			#200    load  <= 1;
			        $display($time, "\t loading machine with %d cans", r_cans);
			#200    load  <= 0;
		end	
	endtask

	task enter_nickel;
		begin
			#100 nickel_in <= 1;
			$display($time, "\t enter nickel");
			#200 nickel_in <= 0;
		end	
	endtask

	task enter_dime;
		begin
			dime_in <= 1;
			$display($time, "\t enter dime");
			#200 dime_in <= 0;
		end	
	endtask

	task enter_quarter;
		begin
			quarter_in <= 1;
			$display($time, "\t enter quarter");
			#200 quarter_in <= 0;
		end	
	endtask

	always @(posedge dispense)
		begin
			$display($time, "\t -> drink dispensed");
			#50 $display("-------------------------------");
		end

	always @(posedge dime_out)
		$display($time, "\t dime changed");

	always @(posedge nickel_out)
		$display($time, "\t nickel changed");

	always @(posedge empty)
		begin
			$display($time, "\t *** machine empty! ***");
		end


endmodule