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
);
    wire c0,c1,c2,c3,c4;
    assign c0 = cin;

    full_adder_1bit g1(a[0],b[0],c0,sum[0],c1);
    full_adder_1bit g2(a[1],b[1],c1,sum[1],c2);
    full_adder_1bit g3(a[2],b[2],c2,sum[2],c3);
    full_adder_1bit g4(a[3],b[3],c3,sum[3],c4);
    assign cout = c4;
endmodule