Modulo arithmetic unit having arbitrary offset and modulo values

摘要

A modulo arithmetic unit for providing a sum or difference of two numbers of arbitrary value in a selected one of a plurality of moduli is provided. Each modulus has a lower and an upper boundary and a range of intermediate values. First and second adders are provided for respectively providing first and second outputs which respectively represent outputs compensated for and not compensated for a possible wraparound of the upper or lower boundary. Control circuitry is used to detect whether a wraparound occurred during the calculation depending upon the value of selective interstage carry signals of the first and second adders. The correct output is provided as a selected one of the outputs of the first and second adders in response to the control circuitry.