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)
    wire xor_a_b;
    assign xor_a_b = a^b;
   assign sum = xor_a_b^cin;
   assign cout = (a&b) |(cin&xor_a_b);
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 c0,c1,c2,c3,c4;
    // TODO: instantiate 4 full adders and chain carries
full_adder_1bit add0(.a(a[0]),.b(b[0]),.cin(c0),.sum(sum[0]),.cout(c1));
full_adder_1bit add1(.a(a[1]),.b(b[1]),.cin(c1),.sum(sum[1]),.cout(c2));
full_adder_1bit add2(.a(a[2]),.b(b[2]),.cin(c2),.sum(sum[2]),.cout(c3));
full_adder_1bit add3(.a(a[3]),.b(b[3]),.cin(c3),.sum(sum[3]),.cout(c4));
assign c0 = cin;
assign cout = c4;

    // TODO: drive cout


endmodule