1. A method for performing signal processing that requires signed multiplication of A times B, wherein B has N bits and A has N*2 bits, and wherein A.sub.high and A.sub.low respectively represent the most and least significant halves of A, said method comprising the computer implemented steps of: logically shifting A.sub.low right by one bit to generate A.sub.low &gt;&gt;1; performing signed multiplication of A.sub.low &gt;&gt;1 by B to generate a first partial result; performing signed multiplication of A.sub.high by B to generate a second partial result; aligning the first and second partial results for addition; and adding the first and second partial results to generate a final result representing A multiplied by B.