`timescale 1ns / 10ps
//////////////////////////////////////////////////////////////////////////////////
//
//  Filename: tb_SevenSegment.v
//
//  Author: Mike Wirthlin
//  
//  Description: Provides a basic testbench for the seven segment decoder lab.
//
//  Version 1.2
//
//  Change Log:
//   
//////////////////////////////////////////////////////////////////////////////////

module tb_SevenSegment();

	reg [3:0] tb_data;
	wire [6:0] tb_segment;
    integer i,j,errors;
    
	reg [6:0] segment_const [15:0];
	
	// Instance the Seven Segment display
    seven_segment ss(.data(tb_data), .segment(tb_segment));    
	
	initial begin

		errors = 0;
        //shall print %t with scaled in ns (-9), with 2 precision digits, and would print the " ns" string
		$timeformat(-9, 0, " ns", 20);
		$display("*** Start of Simulation ***");

		// Intialize constants
		segment_const[0] = 7'b1000000;
		segment_const[1] = 7'b1111001;
		segment_const[2] = 7'b0100100;
		segment_const[3] = 7'b0110000;
		segment_const[4] = 7'b0011001;
		segment_const[5] = 7'b0010010;
		segment_const[6] = 7'b0000010;
		segment_const[7] = 7'b1111000;
		segment_const[8] = 7'b0000000;
		segment_const[9] = 7'b0010000;
		segment_const[10] = 7'b0001000;
		segment_const[11] = 7'b0000011;
		segment_const[12] = 7'b1000110;
		segment_const[13] = 7'b0100001;
		segment_const[14] = 7'b0000110;
		segment_const[15] = 7'b0001110;
		
		errors = 0;
		
		// Don't care at this point (emphasize unknowns)
		#20

		// Initialize
		tb_data = 4'b0000;
		#20
		
		// Test the segments
		for(i=0; i < 16; i=i+1) begin
			#20
			tb_data = i;
			#20
			tb_data = i;
			if (tb_segment == segment_const[i]) begin
				$display("Correct: with data input 0x%1h segments[6:0]=%b at time %0t", 
				i, tb_segment, $time); 
			end	
			//if (tb_segment !== segment_const[i]) begin
			//	$display("*** Error: with data input 0x%1h segment should be '%h' but is '%h' at time %0t", 
			//	i, segment_const[i],tb_segment, $time); 
			//end	
			for (j=0; j < 16; j=j+1) begin
				if (tb_segment[j] !== segment_const[i][j]) begin
					$display("*** Error: with data input 0x%1h segment[%1d] should be '%1d' but is '%1d' at time %0t", 
					i, j, segment_const[i][j],tb_segment[j], $time); 
					errors = errors + 1;
				end
			end
		end

		#20
				
		$display("*** Simulation done with %0d errors at time %0t ***", errors, $time);


	end  // end begin

	
endmodule