Behavioral Description

BEHAVIORAL DESCRIPTION

module cla4 (

    input  [3:0] A, B,     

    input        Cin,      

    output [3:0] Sum,       

    output       Cout       

);

    reg [3:0] Sum;

    reg       Cout;

    reg [3:0] G, P;    

    reg [3:1] C;           

    always @(A or B or Cin)

    begin

        G = A & B;

        P = A ^ B;

        C[1] = G[0] | (P[0] & Cin);

        C[2] = G[1] | (P[1] & C[1]);

        C[3] = G[2] | (P[2] & C[2]);

        Cout  = G[3] | (P[3] & C[3]);

        Sum[0] = P[0] ^ Cin;

        Sum[1] = P[1] ^ C[1];

        Sum[2] = P[2] ^ C[2];

        Sum[3] = P[3] ^ C[3];

    end

endmodule

Test Bench:--

module tb_cla4;

  reg  [3:0] A, B;

  reg        Cin;

  wire [3:0] Sum;

  wire       Cout;

  cla4 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