65. Ripple Carry Adder

How do you plan to solve it?

// 1-bit Full Adder (to be used by the 4-bit RCA)
module full_adder_1bit (
    input  a, b, cin,
    output sum, cout
);
    // TODO: implement 1-bit full adder (structural or dataflow)
    assign {cout,sum}=a+b+cin;

endmodule

// 4-bit Ripple Carry Adder – chain 4 full adders
module rca4_chain (
    input  [3:0] a,
    input  [3:0] b,
    input        cin,
    output [3:0] sum,
    output       cout
);
    // TODO: Declare internal ripple carries
wire[3:0] carry;
    // TODO: instantiate 4 full adders and chain carries
 full_adder_1bit f1(.a(a[0]),.b(b[0]),.cin(cin),.sum(sum[0]),.cout(carry[0]));
 full_adder_1bit f2(.a(a[1]),.b(b[1]),.cin(carry[0]),.sum(sum[1]),.cout(carry[1]));
  full_adder_1bit f3(.a(a[2]),.b(b[2]),.cin(carry[1]),.sum(sum[2]),.cout(carry[2]));
   full_adder_1bit f4(.a(a[3]),.b(b[3]),.cin(carry[2]),.sum(sum[3]),.cout(carry[3]));
    // TODO: drive cout
assign cout=carry[3];

endmodule