| 摘要 |
A logarithm computing circuit for fixed point numbers is disclosed that has: a shift number detection circuit that inputs a number of a fixed point representation, detects a shift number of the inputted number for the purpose of dividing the inputted number into an exponent part and a mantissa part, calculates an exponent part from the shift number and a radix point position of the inputted number, subtracts 1 from the exponent part, and finally outputs the subtraction result as an integer part; a shift circuit that normalizes the inputted number by shifting the inputted number a number of bits equal to the shift number and generates a mantissa part that is equal to or above 0.5 and below 1; and a decimal-part computing circuit that converts the mantissa part to its logarithm to base 2, adds 1 to the conversion result and outputs the result as a decimal part.
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