FUNCTION BLOCK

A function block allows a multiplier and a multi-input multiplexer to be realized with a small number of blocks. A logical function generator generates a logical output signal from first to fourth logical inputs thereof according to a logical function selected from a plurality of 4-input/1-output logical functions depending on configuration data. A 4-2 carry block generates a 4-2 carry output from the second to fourth logical inputs. A first signal is generated from at least the logical output, a second signal from at least the first logical input, a third signal from at least a 4-2 carry input signal, and a fourth signal from at least the 4-2 carry input signal. A multiplexer selects one of the second and third signals depending on the first signal to produce a carry output signal. An exclusive OR circuit produce an exclusive-ORed result from the logical output and the fourth signal.