The present invention relates to a multiply apparatus and a method for multiplying a first
operand consisting of na bits and a second
operand consisting of nx bits. In one embodiment the multiply apparatus comprising a CSA (CSA) unit with nx rows each comprising na AND gates for calculating a single bit product of two single bit input values and
adder cells for adding results of a preceding row to a following row and a last output row for outputting a carry vector and a sum vector, and
logic circuitry for selectively inverting the single bit products at the most significant position of the nx−1 first rows and at the na−1 least significant positions of the output row in response to a first configuration
signal before inputting the selectively inverted single bit products to respective
adder cells for switching the CSA unit selectively between
processing of signed two's complement operands and unsigned operands in response to the first configuration
signal. In one embodiment the method comprising outputting a carry vector and a sum vector, and adding the carry vector and the sum vector provided by the output row of the CSA unit via a CPA unit consisting of a row of na full
adder cells, wherein the carry input of the CPA unit is coupled to receive a first configuration
signal to switch between
processing of signed and unsigned two's complement operands.