Logarithmic conversion apparatus

Abstract

A logarithmic converting apparatus for converting a digital binary integer into logarithmic representation and for converting logarithmic representation into digital binary integer is disclosed. The apparatus determines the bit position of a leading non-zero bit of an integer, shifts the integer such that the leading non-zero bit is the leftmost bit. A look-up table receives the shifted integer and provides a number representative of the mantissa portion of the logarithm of the shifted number. An encoder receives a Point Set Input value, a scale value for said integer, and the number of binary positions shifted and generates the exponential portion of the logarithm of the integer. For converting logarithmic representation of a number into integer representation, the apparatus has a look-up table which receives the mantissa component of the logarithmic representation and provides a first number. A decoder receives the exponential component of the logarithmic representation and a Point Set Output value, a scale value for said integer, and supplies a shifted signal. The shifted signal is supplied to a shifter along with the first number and the shifter shifts the first number by the shift signal to produce the integer.