Arithmetic processor and divider using redundant signed digit

Abstract

An arithmetic processor is disclosed for performing arithmetic operations utilizing an arithmetic operand represented by a signed digit expression having a plurality of digits which may have a positive, zero or negative value. The processor comprises: first circuitry coupled to receive a signal related to the most significant digit of a signed digit expression number Y having nonnegative (or nonpositive) digits other than the most significant digit, and for providing in response to a control signal, a signal representing the logical negation or inversion of the sign of the most significant digit; second circuitry coupled to receive at least one signal related to digits other than the most significant digit of the number Y, and for providing in response to a control signal, at least one signal representing the logical negation or inversion of those digits; and third circuitry coupled to receive a signal related to the least significant digit of the number Y, and for providing in response to a control signal, a signal representing the least significant digit plus 1 (or minus 1). The first and second circuitry invert the signs of the digits of the number Y, and the third circuitry adds (or subtracts) 1 from the least significant digit. The processor also includes circuitry coupled to receive the signals provided by the first, second and third circuitry and a signal representing a number X, and providing a signal representing the sum or difference of the numbers X and Y depending on the control signal.