Digital signal processing block

An apparatus is disclosed. This apparatus includes a digital signal processing ("DSP") block having a preadder-register block coupled to receive first through fourth input operands. A multiplier is coupled to the preadder-register block to receive a multiplicand operand and a multiplier operand. A first register block is coupled to the multiplier to receive sets of partial products from the multiplier. A second register block coupled to receive the third operand input. An arithmetic logic unit ("ALU") block is coupled to the pre-adder-register block, the first register block and the second register block. The ALU block includes four input multiplexers and an ALU, where the ALU is coupled to receive outputs from each of the four input multiplexers.