CLASSIFIED ONE-STEP MODIFIED SIGNED-DIGIT ARITHMETIC AND ITS OPTICAL IMPLEMENTATION

Based on the two-step modified signed-digit (MSD) algorithm, we presen t a one-step algorithm for the parallel addition and subtraction of tw o MSD numbers. This algorithm is reached by classifying the three neig hboring digit pairs into 10 groups and then making a decision on the g roups. It has only a look-up truth table, and can be further formulate d by eight computation rules. A joint spatial encoding technique is de veloped to represent both the input data and the computation rules. Fu rthermore, an optical correlation architecture is suggested to impleme nt the MSD adder in parallel. An experimental demonstration is also gi ven. (C) 1996 Society of Photo-Optical instrumentation Engineers.