n-bit adder/subtractor X89356

Design a circuit that performs the addition or subtraction of two n-bit numbers. The result (mod 2ⁿ) must be represented in n bits also. The circuit has an input (op) that indicates which operation must be performed (0 for addition, 1 for subtraction).

The number of bits must be a parameter of the module, with a default value as shown in the specification.

Specification

module add_sub (a, b, op, result); parameter N=16; input [N-1:0] a, b; input op; output [N-1:0] result;

Input

• a and b are the two n-bit operands.
• op indicates the type of operation (0 for addition, 1 for subtraction).

Output

• result is the n-bit result of the operation (mod 2ⁿ).