// alu4_grader_tb.v

// ALU testbench

// ------------------------------------------------------------------
// Copyright (c) 2007 Susan Lysecky, University of Arizona
// Permission to copy is granted provided that this header remains
// intact. This software is provided with no warranties.
// ------------------------------------------------------------------
`timescale 1ns / 1ps

module Testbench;
// ---------------------------------------------------------------------------
// ALU test module
// ---------------------------------------------------------------------------

   reg [3:0] A_t, B_t;
   reg x_t, y_t, z_t;
	reg Cin_t;
   wire [3:0] Result_t;
	wire Cout_t, Overflow_t;

   ALU_beh ALU_beh_1 (A_t, B_t, x_t, y_t, z_t, Overflow_t, Result_t, Cin_t, Cout_t);
   //ALU_struct ALU_struct_1(A_t, B_t, x_t, y_t, z_t, Overflow_t, Result_t, Cin_t, Cout_t);

   initial
   begin
      Cin_t <= 0;
		
      // ----------------------------------------------
      //case xyz = 000, Result = A
	   // ----------------------------------------------
      x_t <= 0; y_t <= 0; z_t <= 0;

      A_t <= 4'b0000; B_t <= 4'b0000;
      #1 if (Result_t != 4'b0000) $display("Case xyz = %b%b%b, Case 1", x_t, y_t, z_t);
      if (Overflow_t != 0) $display("Overflow Error: Case xyz = %b%b%b, Case 1", x_t, y_t, z_t);
      if (Cout_t != 0) $display("Cout Error: Case xyz = %b%b%b, Case 1", x_t, y_t, z_t);

      A_t <= 4'b0010; B_t <= 4'b1111;
      #1 if (Result_t != 4'b0010) $display("Case xyz = %b%b%b, Case 2", x_t, y_t, z_t);
      if (Overflow_t != 0) $display("Overflow Error: Case xyz = %b%b%b, Case 2", x_t, y_t, z_t);
      if (Cout_t != 0) $display("Cout Error: Case xyz = %b%b%b, Case 2", x_t, y_t, z_t);

      A_t <= 4'b0111; B_t <= 4'b0110;
      #1 if (Result_t != 4'b0111) $display("Case xyz = %b%b%b, Case 3", x_t, y_t, z_t);
      if (Overflow_t != 0) $display("Overflow Error: Case xyz = %b%b%b, Case 3", x_t, y_t, z_t);
      if (Cout_t != 0) $display("Cout Error: Case xyz = %b%b%b, Case 3", x_t, y_t, z_t);

      A_t <= 4'b1111; B_t <= 4'b1111;
      #1 if (Result_t != 4'b1111) $display("Case xyz = %b%b%b, Case 4", x_t, y_t, z_t);
      if (Overflow_t != 0) $display("Overflow Error: Case xyz = %b%b%b, Case 4", x_t, y_t, z_t);
      if (Cout_t != 0) $display("Cout Error: Case xyz = %b%b%b, Case 4", x_t, y_t, z_t);


	   // ----------------------------------------------
      //case xyz = 001, Result = B
	   // ----------------------------------------------
      x_t <= 0; y_t <= 0; z_t <= 1;

      A_t <= 4'b0011; B_t <= 4'b1100;
      #1 if (Result_t != 4'b1100) $display("Case xyz = %b%b%b, Case 1", x_t, y_t, z_t);
      if (Overflow_t != 0) $display("Overflow Error: Case xyz = %b%b%b, Case 1", x_t, y_t, z_t);
      if (Cout_t != 0) $display("Cout Error: Case xyz = %b%b%b, Case 1", x_t, y_t, z_t);

      A_t <= 4'b0110; B_t <= 4'b0000;
      #1 if (Result_t != 4'b0000) $display("Case xyz = %b%b%b, Case 2", x_t, y_t, z_t);
      if (Overflow_t != 0) $display("Overflow Error: Case xyz = %b%b%b, Case 2", x_t, y_t, z_t);
      if (Cout_t != 0) $display("Cout Error: Case xyz = %b%b%b, Case 2", x_t, y_t, z_t);

      A_t <= 4'b0111; B_t <= 4'b0110;
      #1 if (Result_t != 4'b0110) $display("Case xyz = %b%b%b, Case 3", x_t, y_t, z_t);
      if (Overflow_t != 0) $display("Overflow Error: Case xyz = %b%b%b, Case 3", x_t, y_t, z_t);
      if (Cout_t != 0) $display("Cout Error: Case xyz = %b%b%b, Case 3", x_t, y_t, z_t);

      A_t <= 4'b1111; B_t <= 4'b1111;
      #1 if (Result_t != 4'b1111) $display("Case xyz = %b%b%b, Case 4", x_t, y_t, z_t);
      if (Overflow_t != 0) $display("Overflow Error: Case xyz = %b%b%b, Case 4", x_t, y_t, z_t);
      if (Cout_t != 0) $display("Cout Error: Case xyz = %b%b%b, Case 4", x_t, y_t, z_t);


	   // ----------------------------------------------
      //case xyz = 010, Result = A + B
	   // ----------------------------------------------
      x_t <= 0; y_t <= 1; z_t <= 0;

      A_t <= 4'b0000; B_t <= 4'b0000;
      #1 if (Result_t != 4'b0000) $display("Case xyz = %b%b%b, Case 1", x_t, y_t, z_t);
      if (Overflow_t != 0) $display("Overflow Error: Case xyz = %b%b%b, Case 1", x_t, y_t, z_t);
      if (Cout_t != 0) $display("Cout Error: Case xyz = %b%b%b, Case 1", x_t, y_t, z_t);

      A_t <= 4'b1111; B_t <= 4'b1111;
      #1 if (Result_t != 4'b1110) $display("Case xyz = %b%b%b, Case 2", x_t, y_t, z_t);
      if (Overflow_t != 0) $display("Overflow Error: Case xyz = %b%b%b, Case 2", x_t, y_t, z_t);
      if (Cout_t != 1) $display("Cout Error: Case xyz = %b%b%b, Case 2", x_t, y_t, z_t);

      A_t <= 4'b0001; B_t <= 4'b0011;
      #1 if (Result_t != 4'b0100) $display("Case xyz = %b%b%b, Case 3", x_t, y_t, z_t);
      if (Overflow_t != 0) $display("Overflow Error: Case xyz = %b%b%b, Case 3", x_t, y_t, z_t);
      if (Cout_t != 0) $display("Cout Error: Case xyz = %b%b%b, Case 3", x_t, y_t, z_t);

      A_t <= 4'b0110; B_t <= 4'b0100;
      #1 if (Result_t != 4'b1010) $display("Case xyz = %b%b%b, Case 4", x_t, y_t, z_t);
      if (Overflow_t != 1) $display("Overflow Error: Case xyz = %b%b%b, Case 4", x_t, y_t, z_t);
      if (Cout_t != 0) $display("Cout Error: Case xyz = %b%b%b, Case 4", x_t, y_t, z_t);

      A_t <= 4'b1110; B_t <= 4'b1101;
      #1 if (Result_t != 4'b1011) $display("Case xyz = %b%b%b, Case 5", x_t, y_t, z_t);
      if (Overflow_t != 0) $display("Overflow Error: Case xyz = %b%b%b, Case 5", x_t, y_t, z_t);
      if (Cout_t != 1) $display("Cout Error: Case xyz = %b%b%b, Case 5", x_t, y_t, z_t);

      A_t <= 4'b1001; B_t <= 4'b1101;
      #1 if (Result_t != 4'b0110) $display("Case xyz = %b%b%b, Case 6", x_t, y_t, z_t);
      if (Overflow_t != 1) $display("Overflow Error: Case xyz = %b%b%b, Case 6", x_t, y_t, z_t);
      if (Cout_t != 1) $display("Cout Error: Case xyz = %b%b%b, Case 6", x_t, y_t, z_t);

      A_t <= 4'b1001; B_t <= 4'b0011;
      #1 if (Result_t != 4'b1100) $display("Case xyz = %b%b%b, Case 7", x_t, y_t, z_t);
      if (Overflow_t != 0) $display("Overflow Error: Case xyz = %b%b%b, Case 7", x_t, y_t, z_t);
      if (Cout_t != 0) $display("Cout Error: Case xyz = %b%b%b, Case 7", x_t, y_t, z_t);

      A_t <= 4'b0001; B_t <= 4'b1111;
      #1 if (Result_t != 4'b0000) $display("Case xyz = %b%b%b, Case 8", x_t, y_t, z_t);
      if (Overflow_t != 0) $display("Overflow Error: Case xyz = %b%b%b, Case 8", x_t, y_t, z_t);
      if (Cout_t != 1) $display("Cout Error: Case xyz = %b%b%b, Case 8", x_t, y_t, z_t);


   	// ----------------------------------------------
      //case xyz = 011, Result = A - B
	   // ----------------------------------------------
      x_t <= 0; y_t <= 1; z_t <= 1;

      A_t <= 4'b0000; B_t <= 4'b0000;
      #1 if (Result_t != 4'b0000) $display("Case xyz = %b%b%b, Case 1", x_t, y_t, z_t);
      if (Overflow_t != 0) $display("Overflow Error: Case xyz = %b%b%b, Case 1", x_t, y_t, z_t);
      if (Cout_t != 1) $display("Cout Error: Case xyz = %b%b%b, Case 1", x_t, y_t, z_t);

      A_t <= 4'b1111; B_t <= 4'b1111;
      #1 if (Result_t != 4'b0000) $display("Case xyz = %b%b%b, Case 2", x_t, y_t, z_t);
      if (Overflow_t != 0) $display("Overflow Error: Case xyz = %b%b%b, Case 2", x_t, y_t, z_t);
      if (Cout_t != 1) $display("Cout Error: Case xyz = %b%b%b, Case 2", x_t, y_t, z_t);

      A_t <= 4'b0111; B_t <= 4'b0100;
      #1 if (Result_t != 4'b0011) $display("Case xyz = %b%b%b, Case 3", x_t, y_t, z_t);
      if (Overflow_t != 0) $display("Overflow Error: Case xyz = %b%b%b, Case 3", x_t, y_t, z_t);
      if (Cout_t != 1) $display("Cout Error: Case xyz = %b%b%b, Case 3", x_t, y_t, z_t);

      A_t <= 4'b0010; B_t <= 4'b0111;
      #1 if (Result_t != 4'b1011) $display("Case xyz = %b%b%b, Case 4", x_t, y_t, z_t);
      if (Overflow_t != 0) $display("Overflow Error: Case xyz = %b%b%b, Case 4", x_t, y_t, z_t);
      if (Cout_t != 0) $display("Cout Error: Case xyz = %b%b%b, Case 4", x_t, y_t, z_t);

      A_t <= 4'b1000; B_t <= 4'b1100;
      #1 if (Result_t != 4'b1100) $display("Case xyz = %b%b%b, Case 5", x_t, y_t, z_t);
      if (Overflow_t != 0) $display("Overflow Error: Case xyz = %b%b%b, Case 5", x_t, y_t, z_t);
      if (Cout_t != 0) $display("Cout Error: Case xyz = %b%b%b, Case 5", x_t, y_t, z_t);

      A_t <= 4'b1110; B_t <= 4'b1100;
      #1 if (Result_t != 4'b0010) $display("Case xyz = %b%b%b, Case 6", x_t, y_t, z_t);
      if (Overflow_t != 0) $display("Overflow Error: Case xyz = %b%b%b, Case 6", x_t, y_t, z_t);
      if (Cout_t != 1) $display("Cout Error: Case xyz = %b%b%b, Case 6", x_t, y_t, z_t);

      A_t <= 4'b1100; B_t <= 4'b0011;
      #1 if (Result_t != 4'b1001) $display("Case xyz = %b%b%b, Case 7", x_t, y_t, z_t);
      if (Overflow_t != 0) $display("Overflow Error: Case xyz = %b%b%b, Case 7", x_t, y_t, z_t);
      if (Cout_t != 1) $display("Cout Error: Case xyz = %b%b%b, Case 7", x_t, y_t, z_t);

      A_t <= 4'b0001; B_t <= 4'b1011;
      #1 if (Result_t != 4'b0110) $display("Case xyz = %b%b%b, Case 8", x_t, y_t, z_t);
      if (Overflow_t != 0) $display("Overflow Error: Case xyz = %b%b%b, Case 8", x_t, y_t, z_t);
      if (Cout_t != 0) $display("Cout Error: Case xyz = %b%b%b, Case 8", x_t, y_t, z_t);

      A_t <= 4'b1011; B_t <= 4'b0101;
      #1 if (Result_t != 4'b0110) $display("Case xyz = %b%b%b, Case 9", x_t, y_t, z_t);
      if (Overflow_t != 1) $display("Overflow Error: Case xyz = %b%b%b, Case 9", x_t, y_t, z_t);
      if (Cout_t != 1) $display("Cout Error: Case xyz = %b%b%b, Case 9", x_t, y_t, z_t);

	   // ----------------------------------------------
      //case xyz = 100, Result = A + 1
	   // ----------------------------------------------
      x_t <= 1; y_t <= 0; z_t <= 0;
		
      A_t <= 4'b0000; B_t <= 4'b0000;
      #1 if (Result_t != 4'b0001) $display("xyz = %b%b%b, Case 1", x_t, y_t, z_t);
      if (Overflow_t != 0) $display("Overflow Error: Case xyz = %b%b%b, Case 1", x_t, y_t, z_t);
      if (Cout_t != 0) $display("Cout Error: Case xyz = %b%b%b, Case 1", x_t, y_t, z_t);

      A_t <= 4'b1111; B_t <= 4'b1111;
      #1 if (Result_t != 4'b0000) $display("xyz = %b%b%b, Case 2", x_t, y_t, z_t);
      if (Overflow_t != 0) $display("Overflow Error: Case xyz = %b%b%b, Case 2", x_t, y_t, z_t);
      if (Cout_t != 1) $display("Cout Error: Case xyz = %b%b%b, Case 2", x_t, y_t, z_t);

      A_t <= 4'b0110; B_t <= 4'b0000;
      #1 if (Result_t != 4'b0111) $display("xyz = %b%b%b, Case 3", x_t, y_t, z_t);
      if (Overflow_t != 0) $display("Overflow Error: Case xyz = %b%b%b, Case 3", x_t, y_t, z_t);
      if (Cout_t != 0) $display("Cout Error: Case xyz = %b%b%b, Case 3", x_t, y_t, z_t);

      A_t <= 4'b0111; B_t <= 4'b0000;
      #1 if (Result_t != 4'b1000) $display("xyz = %b%b%b, Case 4", x_t, y_t, z_t);
      if (Overflow_t != 1) $display("Overflow Error: Case xyz = %b%b%b, Case 4", x_t, y_t, z_t);
      if (Cout_t != 0) $display("Cout Error: Case xyz = %b%b%b, Case 4", x_t, y_t, z_t);

      A_t <= 4'b1010; B_t <= 4'b1111;
      #1 if (Result_t != 4'b1011) $display("xyz = %b%b%b, Case 5", x_t, y_t, z_t);
      if (Overflow_t != 0) $display("Overflow Error: Case xyz = %b%b%b, Case 5", x_t, y_t, z_t);
      if (Cout_t != 0) $display("Cout Error: Case xyz = %b%b%b, Case 5", x_t, y_t, z_t);


	   // ----------------------------------------------
      //case xyz = 101, Result = A'
	   // ----------------------------------------------
      x_t <= 1; y_t <= 0; z_t <= 1;

      A_t <= 4'b0000; B_t <= 4'b0000;
      #1 if (Result_t != 4'b1111) $display("xyz = %b%b%b, Case 1", x_t, y_t, z_t);
      if (Overflow_t != 0) $display("Overflow Error: Case xyz = %b%b%b, Case 1", x_t, y_t, z_t);
      if (Cout_t != 0) $display("Cout Error: Case xyz = %b%b%b, Case 1", x_t, y_t, z_t);

      A_t <= 4'b1111; B_t <= 4'b1111;
      #1 if (Result_t != 4'b0000) $display("xyz = %b%b%b, Case 2", x_t, y_t, z_t);
      if (Overflow_t != 0) $display("Overflow Error: Case xyz = %b%b%b, Case 2", x_t, y_t, z_t);
      if (Cout_t != 0) $display("Cout Error: Case xyz = %b%b%b, Case 2", x_t, y_t, z_t);

      A_t <= 4'b0110; B_t <= 4'b0000;
      #1 if (Result_t != 4'b1001) $display("xyz = %b%b%b, Case 3", x_t, y_t, z_t);
      if (Overflow_t != 0) $display("Overflow Error: Case xyz = %b%b%b, Case 3", x_t, y_t, z_t);
      if (Cout_t != 0) $display("Cout Error: Case xyz = %b%b%b, Case 3", x_t, y_t, z_t);

      A_t <= 4'b1100; B_t <= 4'b0000;
      #1 if (Result_t != 4'b0011) $display("xyz = %b%b%b, Case 4", x_t, y_t, z_t);
      if (Overflow_t != 0) $display("Overflow Error: Case xyz = %b%b%b, Case 4", x_t, y_t, z_t);
      if (Cout_t != 0) $display("Cout Error: Case xyz = %b%b%b, Case 4", x_t, y_t, z_t);


	   // ----------------------------------------------
      //case xyz = 110, Result = A AND B
	   // ----------------------------------------------
      x_t <= 1; y_t <= 1; z_t <= 0;

      A_t <= 4'b0000; B_t <= 4'b0000;
      #1 if (Result_t != 4'b0000) $display("Case xyz = %b%b%b, Case 1", x_t, y_t, z_t);
      if (Overflow_t != 0) $display("Overflow Error: Case xyz = %b%b%b, Case 1", x_t, y_t, z_t);
      if (Cout_t != 0) $display("Cout Error: Case xyz = %b%b%b, Case 1", x_t, y_t, z_t);

      A_t <= 4'b0000; B_t <= 4'b1111;
      #1 if (Result_t != 4'b0000) $display("Case xyz = %b%b%b, Case 2", x_t, y_t, z_t);
      if (Overflow_t != 0) $display("Overflow Error: Case xyz = %b%b%b, Case 2", x_t, y_t, z_t);
      if (Cout_t != 0) $display("Cout Error: Case xyz = %b%b%b, Case 2", x_t, y_t, z_t);

      A_t <= 4'b0110; B_t <= 4'b0010;
      #1 if (Result_t != 4'b0010) $display("Case xyz = %b%b%b, Case 3", x_t, y_t, z_t);
      if (Overflow_t != 0) $display("Overflow Error: Case xyz = %b%b%b, Case 3", x_t, y_t, z_t);
      if (Cout_t != 0) $display("Cout Error: Case xyz = %b%b%b, Case 3", x_t, y_t, z_t);

      A_t <= 4'b1010; B_t <= 4'b1111;
      #1 if (Result_t != 4'b1010) $display("Case xyz = %b%b%b, Case 4", x_t, y_t, z_t);
      if (Overflow_t != 0) $display("Overflow Error: Case xyz = %b%b%b, Case 4", x_t, y_t, z_t);
      if (Cout_t != 0) $display("Cout Error: Case xyz = %b%b%b, Case 4", x_t, y_t, z_t);

      A_t <= 4'b1111; B_t <= 4'b1111;
      #1 if (Result_t != 4'b1111) $display("Case xyz = %b%b%b, Case 5", x_t, y_t, z_t);
      if (Overflow_t != 0) $display("Overflow Error: Case xyz = %b%b%b, Case 5", x_t, y_t, z_t);
      if (Cout_t != 0) $display("Cout Error: Case xyz = %b%b%b, Case 5", x_t, y_t, z_t);


	   // ----------------------------------------------
      //case xyz = 111, Result = A OR B
	   // ----------------------------------------------
      x_t <= 1; y_t <= 1; z_t <= 1;
		
		
      A_t <= 4'b0000; B_t <= 4'b0000;
      #1 if (Result_t != 4'b0000) $display("Case xyz = %b%b%b, Case 1", x_t, y_t, z_t);
      if (Overflow_t != 0) $display("Overflow Error: Case xyz = %b%b%b, Case 1", x_t, y_t, z_t);
      if (Cout_t != 0) $display("Cout Error: Case xyz = %b%b%b, Case 1", x_t, y_t, z_t);

      A_t <= 4'b0000; B_t <= 4'b1111;
      #1 if (Result_t != 4'b1111) $display("Case xyz = %b%b%b, Case 2", x_t, y_t, z_t);
      if (Overflow_t != 0) $display("Overflow Error: Case xyz = %b%b%b, Case 2", x_t, y_t, z_t);
      if (Cout_t != 0) $display("Cout Error: Case xyz = %b%b%b, Case 2", x_t, y_t, z_t);

      A_t <= 4'b0110; B_t <= 4'b0010;
      #1 if (Result_t != 4'b0110) $display("Case xyz = %b%b%b, Case 3", x_t, y_t, z_t);
      if (Overflow_t != 0) $display("Overflow Error: Case xyz = %b%b%b, Case 3", x_t, y_t, z_t);
      if (Cout_t != 0) $display("Cout Error: Case xyz = %b%b%b, Case 3", x_t, y_t, z_t);

      A_t <= 4'b1010; B_t <= 4'b1111;
      #1 if (Result_t != 4'b1111) $display("Case xyz = %b%b%b, Case 4", x_t, y_t, z_t);
      if (Overflow_t != 0) $display("Overflow Error: Case xyz = %b%b%b, Case 4", x_t, y_t, z_t);
      if (Cout_t != 0) $display("Cout Error: Case xyz = %b%b%b, Case 4", x_t, y_t, z_t);

      A_t <= 4'b1111; B_t <= 4'b1111;
      #1 if (Result_t != 4'b1111) $display("Case xyz = %b%b%b, Case 5", x_t, y_t, z_t);
      if (Overflow_t != 0) $display("Overflow Error: Case xyz = %b%b%b, Case 5", x_t, y_t, z_t);
      if (Cout_t != 0) $display("Cout Error: Case xyz = %b%b%b, Case 5", x_t, y_t, z_t);


   end

endmodule