//
// Title       : 4 bit alu test fixture
// Design      : Homework 5
// Author      : Steven Balensiefer, Carl Ebeling
// Company     : CSE 370
//
//-------------------------------------------------------------------------------------------------
//
// File        : alu_4bit_tf.v
//
// Description : This test fixture tests a 4-bit ALU made from 4 ALU bit-slices;
//-------------------------------------------------------------------------------------------------
`timescale 1ns / 1ns


module alu_4bit_tf (A, B, Sel, Cin, F, Cout);

output [3:0] A, B;
output [2:0] Sel;		// Data input, control to ALU
output Cin;
input [3:0] F;		// Results from adder
input Cout;

reg [3:0] A, B;
reg [2:0] Sel;		// Data input to adder
reg [3:0] Val;
reg VCo;
reg Cin;

integer	errors;
integer count;
integer funct;
integer i, good;

initial	begin  
	errors = 0;
	// Perform exhaustive test:
	for (funct = 1; funct < 7; funct = funct + 1) begin
		Sel = funct;
		Cin = (funct == 1 || funct == 2)? 1'b1 : 1'b0;
		for (count = 0; count < 256; count = count + 1) begin
			{A,B} = count;
			#20
			good = 1; 
			case(funct)
			0 :	{VCo,Val} = 5'b00000;
			1 : {VCo,Val} = B + (~A) + 1; 
			2 : {VCo,Val} = A + (~B) + 1;
			3 : {VCo,Val} = A + B;
			4 : {VCo,Val} = {1'b0,A[3:0]^B[3:0]};
			5 : {VCo,Val} = {1'b0,A[3:0]|B[3:0]};
			6 : {VCo,Val} = {1'b0,A[3:0]&B[3:0]};
			7 : {VCo,Val} = 5'b01111;
			default $display(  "Error in funct"  );
		    endcase
			for (i = 0; i < 4; i = i + 1) begin
				if (Val[i] !== F[i])
					good = 0; 	
			end	   				
			if (!good) begin
			$display("***Error*** A:%b, B:%b, Cin%b, Sel:%b, F:%b, Cout:%b\nShould Be F:%b, Cout:%b", A, B, Cin, Sel, F, Cout,Val,VCo);
			errors = errors + 1;
			$stop; 
			end
		end
		
	end
	if (errors == 0) $display("Test passed - No errors!!");
	else $display("**** %d Errors****", errors);	 
end
endmodule