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 {cout, sum} = 2'b00 + a + b + 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 [4:0] c;
full_adder_1bit fa0 (.a(a[0]), .b(b[0]), .cin(c[0]), .sum(sum[0]), .cout(c[1]));
full_adder_1bit fa1 (.a(a[1]), .b(b[1]), .cin(c[1]), .sum(sum[1]), .cout(c[2]));
full_adder_1bit fa2 (.a(a[2]), .b(b[2]), .cin(c[2]), .sum(sum[2]), .cout(c[3]));
full_adder_1bit fa3 (.a(a[3]), .b(b[3]), .cin(c[3]), .sum(sum[3]), .cout(c[4]));

assign c[0] = cin;
assign cout = c[4];

endmodule