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 sum=a^b^cin;
    assign cout=(a&b)|(b&cin)|(a&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 c1, c2, c3;

    // TODO: instantiate 4 full adders and chain carries

    full_adder_1bit fa0(
        .a(a[0]) , 
        .b(b[0]) , 
        .cin(cin) , 
        .sum(sum[0]) , 
        .cout(c1)
    );

    full_adder_1bit fa1(
        .a(a[1]) , 
        .b(b[1]) , 
        .cin(c1) , 
        .sum(sum[1]) , 
        .cout(c2)
    );

        full_adder_1bit fa2(
        .a(a[2]) , 
        .b(b[2]) , 
        .cin(c2) , 
        .sum(sum[2]) , 
        .cout(c3)
    );

        full_adder_1bit fa3(
        .a(a[3]) , 
        .b(b[3]) , 
        .cin(c3) , 
        .sum(sum[3]) , 
        .cout(cout)
    );



    
    // TODO: drive cout


endmodule