Importance

Loading Importance Indicators...

Abstract

A digital signal processor (DSP) computes logarithmic values for data values of the input signal by using an approximation formula expanded into power series. To reduce the number of computing steps, the processor includes a shift circuit for shifting an input data value into a predetermined range of numeric values, a high-order coefficient memory for storing coefficient values of high order coefficients other than a zero-order coefficient of the approximation formula for data values within the predetermined range of numeric values, a zero-order coefficient memory for storing a coefficient value of the zero-order coefficient shifted according to the number of digits shifted by the shift circuit, and an address specifying circuit for specifying a reading address of the zero-order memory corresponding to the number of digit shifted by the shifted circuit. Also, a DSP computes an inverse logarithmic value of a data value of the input signal by using an approximation formula expanded into power series. The processor includes a summing circuit for summing a specific value to an input data value so that a summed value falls within a predetermined range of numeric values, a coefficient memory for storing coefficient values of the approximation formula for data values within the predetermined range of numeric values, and a shift circuit for shifting a result of computation performed by using the approximation formula by a number of digits corresponding to the specific value summed by the summing circuit.

First Claim