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)|(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 c0,c1,c2,c3;
    full_adder_1bit f0(a[0],b[0],cin,sum[0],c0);
 full_adder_1bit f1(a[1],b[1],c0,sum[1],c1);
  full_adder_1bit f2(a[2],b[2],c1,sum[2],c2);
   full_adder_1bit f3(a[3],b[3],c2,sum[3],c3);
    // TODO: instantiate 4 full adders and chain carries
  assign cout=c3;

    // TODO: drive cout


endmodule