Patent ID: 7266576
Filing Date: 2007-09-04
Classification: G06F

Abstract:
1. A method of approximating a base 2 logarithm of a binary input utilizing a digital circuit, the binary input comprised of a first binary number of bits, the method comprising the steps of: partitioning the binary input into at least two partitions, each one of said at least two partitions comprised of a second binary number of bits, said second binary number being smaller than said first binary number of bits; determining a most significant one of said at least two partitions; determining an integer part of the approximation; providing as input to a lookup table a binary representation of the bits in said second binary number of bits corresponding to said most significant one of said partitions; obtaining an output from the lookup table, said output being a binary representation of a mantissa for the logarithm of base 2 of the input to the lookup table; determining a second most significant one of said at least two partitions; obtaining a third binary number by appending of portion of a binary representation of the bits in said second binary number of bits corresponding to the partition to the right of the second most significant one of said at least two partitions; obtaining a residual binary output from shifting said third binary number by a shift determined by said integer portion of the base 2 logarithm of the binary input; and, adding the residual binary output to the output from the lookup table to obtain the mantissa of the approximation to the base 2 logarithm of the binary input; the mantissa and the integer part providing an approximation to the base 2 logarithm of the binary input; said method a group of steps producing the lookup table output and a group of steps resulting in said residual binary output operating concurrently; and there being no dependencies between the two groups of steps; the approximation to the base 2 logarithm of the binary input being used in a system for an application; whereby the application is radar, a calculator or audio; the method being implementable in hardware and requiring substantially minimal hardware computation cycles.