UNIFIED NEGABINARY SYMBOLIC ARITHMETIC FOR ADDITION AND SUBTRACTION WITH POLARIZATION-ENCODED OPTICAL SHADOW-CASTING

Conventional algorithms process addition and subtraction in different ways. In this paper, by introducing bipolar carries, a unified negabin ary symbolic arithmetic for the two operations can be derived, using o nly the same six substitution rules. Based on the polarization-encoded optical shadow-casting technique, the encoding and decoding patterns for half-addition, half-subtraction and unified arithmetic are designe d, with the fixed LED pattern and separate and simultaneous generation of the multi-outputs. The architecture is simple, programmable, cost- efficient, and the addition and subtraction of multiple pairs of bipol ar numbers can be handled in parallel in the same manner. (C) 1997 Els evier Science Ltd.