[adrian_b]

There is no need for a specialized adder.

The patented expression is computable in an obvious way by a single ordinary adder and a single AND gate connected to the carry input of the adder, without any other devices (the shifts and the "& 1" are done by appropriate connections).

Any ordinary N-bit adder computes the sum of 3 input operands, 2 which are N-bit, and a third which is an 1-bit carry.