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
);
    assign sum = a ^ b ^ cin;
    assign cout = ((a ^ b) & cin) | (a & b);
    // TODO: implement 1-bit full adder (structural or dataflow)

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 sum1, sum2, sum3, sum4;
    wire cout1, cout2, cout3, cout4;
    
    // TODO: instantiate 4 full adders and chain carries
    full_adder_1bit a1 (a[0],b[0],cin,sum1,cout1);
    full_adder_1bit a2 (a[1],b[1],cout1, sum2, cout2);
    full_adder_1bit a3 (a[2],b[2],cout2, sum3, cout3);
    full_adder_1bit a4 (a[3],b[3],cout3, sum4, cout4);

    assign sum = {sum4,sum3,sum2,sum1};
    assign cout = cout4;

    // TODO: drive cout


endmodule