Behavioral Description

BEHAVIORAL DESCRIPTION 

module ripple_carry_adder4 (

    input  [3:0] A, B,      

    input        Cin,      

    output [3:0] Sum,         

    output       Cout        

);

    reg [3:0] Sum;

    reg       Cout;

    always @(A or B or Cin)

    begin

        {Cout, Sum} = A + B + Cin;  

    end

endmodule

Test Bench:--

module tb_ripple_carry_adder4;

  reg  [3:0] A, B;

  reg        Cin;

  wire [3:0] Sum;

  wire       Cout;

  ripple_carry_adder4 uut (

    .A(A),

    .B(B),

    .Cin(Cin),

    .Sum(Sum),

    .Cout(Cout)

  );

  initial

  begin

    A = 4'b0001; B = 4'b0010; Cin = 0;

    #10;

    A = 4'b0101; B = 4'b0011; Cin = 0;

    #10;

    A = 4'b1111; B = 4'b0001; Cin = 0;

    #10;

    A = 4'b1010; B = 4'b0101; Cin = 1;

    #10;

    A = 4'b1111; B = 4'b1111; Cin = 1;

    #10;

    $finish;

  end

endmodule

OUTPUT