Patent ID: 6032169
Filing Date: 2000-02-29
Classification: G06F

Abstract:
An arithmetic circuit for calculating the square of a first number presented in the form of a concatenation of sub-numbers of successive significance, each of which comprises the same number of digits, which circuit includes:a multiplier circuit having at least two inputs, each of which is intended for a sub-number, and one output for supplying a product, having twice the length of the sub-numbers, for the parallel multiplication of each time a first sub-number and a second sub-number of the first number;an adder having one output and at least two inputs, a first input being connectable to the output of the multiplier circuit;a register having a plurality of register cells for storing a plurality of sub-numbers, which register comprises an input which can be coupled to the output of the adder in order to receive a sub-word and to store the sub-word in a selected register cell, and an output which can be coupled to the second input of the adder in order to output a sub-word from a selected register cell, andA control circuit for controlling the successive supply of two sub-numbers to the multiplier circuit and for controlling the adder and the register for positionally correct addition of the product obtained at the output of the multiplier circuit to the content of the appropriate register cell of the register,characterized in that the multiplier circuit includes a controllable shift circuit which is connected between one of the inputs and the output in order to perform, at option, either a shift of one position to the left, corresponding to a multiplication by the factor 2, or not shift, the control circuit being arranged to apply, for each first sub-number applied to one input of the multiplier circuit, successively only a second sub-number of the same or higher significance to the other input and to switch the shift circuit over for a shift of one position to the left when a second sub-number having a significance higher than that of the first sub-number is supplied.