Method and apparatus for encoding and decoding data in residue number

Abstract

In a method and apparatus for encoding and decoding data in the residue number system, input binary data are supplied to an encoder to be divided by moduli m.sub.0, m.sub.1, m.sub.2, . . . m (i.e., positive integers having a mutually prime relation). Residue data corresponding to respective moduli are output from the encoder to a digital filter circuit including a plurality of digital filters, each filter corresponding to a respective modulus. Processing for some specified application is performed by the digital filters based, for example, on the Mixed Radix Conversion Method method to generate output data still in the residue format. The residue data output from the digital filters then are input to a decoder to be converted back into binary data. Encoding is performed by splitting n-bit straight binary data into, for example, upper bit data and lower bit data, received by respective ROM tables. Each ROM table outputs a value to another common ROM table which outputs the converted residue data. The ROM tables convert the binary data by weighing each input bit by a value corresponding to the particular bit. The capacity needed for the ROM tables is reduced, enabling the encoder circuit configuration to be simple and fast. Decoding is performed by scaling down RNS data to obtain a plurality of residue data corresponding to respective moduli, adding one to a fixed bit of the residue data for discriminating positive and negative numbers, and performing addition on such residue data with fixed moduli to obtain binary data.