Bcdadd4
From HDLBits
You are provided with a BCD (binary-coded decimal) one-digit adder named bcd_fadd that adds two BCD digits and carry-in, and produces a sum and carry-out.
module bcd_fadd ( input [3:0] a, input [3:0] b, input cin, output cout, output [3:0] sum );
Instantiate 4 copies of bcd_fadd to create a 4-digit BCD ripple-carry adder. Your adder should add two 4-digit BCD numbers (packed into 16-bit vectors) and a carry-in to produce a 4-digit sum and carry out.
Module Declaration
module top_module ( input [15:0] a, b, input cin, output cout, output [15:0] sum );