Verilog Add 4 Bit Code

Verilog Add 4 Bit Code

`timescale 1ns / 1ps

//////////////////////////////////////////////////////////////////////////////////
module Add4bit(
    input [3:0] A,
    input [3:0] B,
    output Cout,
    output [3:0] S
    );
    wire [2:0] tmp;
    HA U0(.A(A[0]),.B(B[0]),.Cout(tmp[0]),.S(S[0]));
    FA U1(.A(A[1]),.B(B[1]),.Cin(tmp[0]),.Cout(tmp[1]),.S(S[1]));
    FA U2(.A(A[2]),.B(B[2]),.Cin(tmp[1]),.Cout(tmp[2]),.S(S[2]));
    FA U3(.A(A[3]),.B(B[3]),.Cin(tmp[2]),.Cout(Cout),.S(S[3]));
endmodule