module sim_alu;				// file ¡°sim_alu.v¡±

wire [3:0] ALUctl;
reg [31:0] A, B;
wire [31:0] ALUOut;
wire Zero;

reg [1:0] ALUOp;
reg [5:0] Func;


aluctrl ALUC1 (ALUOp, Func, ALUctl);
alu ALU1 (ALUctl, A, B, ALUOut, Zero);

initial begin

	//*****************
	//1st run for A < B
	//*****************

	A = 32'd13;		//32'b0_1101
	B = 32'd20;		//32'b1_0100

	$display("\n***** 1st Run *****");
	$display("A (1st) =", A);
	$display("B (2nd) =", B);

	ALUOp = 2'd2;
	Func = 6'h20;
	//ALUctl = 4'd2;
	#1;			//This is for waiting until output is settled down.
	$display("   ADD");
	$display("ALUOut = ", ALUOut);
	$display("Zero   = ", Zero);

	ALUOp = 2'd2;
	Func = 6'h22;
	//ALUctl = 4'd6;
	#1;
	$display("   SUB");
	$display("ALUOut = ", ALUOut); //should be negative
	$display("Zero   = ", Zero);

	ALUOp = 2'd2;
	Func = 6'h24;
	//ALUctl = 4'd0;
	#1;
	$display("   AND");
	$display("ALUOut = ", ALUOut);
	$display("Zero   = ", Zero);

	ALUOp = 2'd2;
	Func = 6'h25;
	//ALUctl = 4'd1;
	#1;
	$display("   OR");
	$display("ALUOut = ", ALUOut); //should be 1 (set)
	$display("Zero   = ", Zero);

	ALUOp = 2'd2;
	Func = 6'h2a;
	//ALUctl = 4'd7;
	#1;
	$display("   SLT");
	$display("ALUOut = ", ALUOut);
	$display("Zero   = ", Zero);

	//*****************
	//2nd run for A = B
	//*****************

	A = 32'd20;		//32'b1_0100
	B = 32'd20;		//32'b1_0100

	$display("\n***** 2nd Run *****");
	$display("A (1st) =", A);
	$display("B (2nd) =", B);

	ALUOp = 2'd2;
	Func = 6'h20;
	//ALUctl = 4'd2;
	#1;			//This is for waiting until output is settled down.
	$display("   ADD");
	$display("ALUOut = ", ALUOut);
	$display("Zero   = ", Zero);

	ALUOp = 2'd2;
	Func = 6'h22;
	//ALUctl = 4'd6;
	#1;
	$display("   SUB");
	$display("ALUOut = ", ALUOut); //should be negative
	$display("Zero   = ", Zero);

	ALUOp = 2'd2;
	Func = 6'h24;
	//ALUctl = 4'd0;
	#1;
	$display("   AND");
	$display("ALUOut = ", ALUOut);
	$display("Zero   = ", Zero);

	ALUOp = 2'd2;
	Func = 6'h25;
	//ALUctl = 4'd1;
	#1;
	$display("   OR");
	$display("ALUOut = ", ALUOut); //should be 1 (set)
	$display("Zero   = ", Zero);

	ALUOp = 2'd2;
	Func = 6'h2a;
	//ALUctl = 4'd7;
	#1;
	$display("   SLT");
	$display("ALUOut = ", ALUOut);
	$display("Zero   = ", Zero);

	$finish;
end

endmodule