//
// Title       : 16-1 multiplexer test fixture
// Author      : Carl Ebeling
// Company     : CSE 370
//
//-------------------------------------------------------------------------------------------------
//
// File        : mux16_tf.v
//
// Description : This test fixture tests the 16-1 multiplexer.  We can't try all combinations,
//				 so we'll generate random tests on the D input while trying many select combinations
//
//-------------------------------------------------------------------------------------------------
`timescale 1ns / 1ns


module mux16_tf (D, S, Q);

output [15:0] D;
output [3:0] S;
input Q;
reg [15:0] D;
reg [3:0] S;

integer	errors;
integer count;

initial	begin  
	errors = 0;	   
	for (count = 0; count < 1024; count = count + 1) begin
		{ S } = count;	// Sets S from the low order bits of count
		D = $random;	// Set D to a random 16-bit value
		#10	// Wait 10 ns.
		if (Q != D[S]) begin
			$display("***Error*** D:%b, S:%d, Q:%b", D, S, Q); 
			errors = errors + 1;
			$stop; 		// Stop simulation so we can look at error
		end
		
	end
	if (errors == 0) $display("Test passed - No errors!!");
		else $display("**** %d Errors****", errors);
end
	
endmodule