A carry look-ahead adder capable of adding or subtracting two input signals includes
first stage logic having a plurality of carry-create and carry-transmit logic circuits
each coupled to receive one or more bits of each input signal. Each carry-create
circuit generates a novel carry-create signal in response to corresponding first
bit-pairings of the input signals, and each carry-transmit circuit generates a
novel carry-transmit signal in response to corresponding second bit-pairings of
the input signals. The carry-create and carry-transmit signals are combined in
carry look-ahead logic to generate accumulated carry-create signals, which are
then used to select final sum bits.