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 /* * dvb-math provides some complex fixed-point math * operations shared between the dvb related stuff * * Copyright (C) 2006 Christoph Pfister (christophpfister@gmail.com) * * This library is free software; you can redistribute it and/or modify * it under the terms of the GNU Lesser General Public License as * published by the Free Software Foundation; either version 2.1 of * the License, or (at your option) any later version. * * This program is distributed in the hope that it will be useful, * but WITHOUT ANY WARRANTY; without even the implied warranty of * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the * GNU Lesser General Public License for more details. */ #ifndef __DVB_MATH_H #define __DVB_MATH_H #include /** * intlog2 - computes log2 of a value; the result is shifted left by 24 bits * * @value: The value (must be != 0) * * to use rational values you can use the following method: * * intlog2(value) = intlog2(value * 2^x) - x * 2^24 * * Some usecase examples: * * intlog2(8) will give 3 << 24 = 3 * 2^24 * * intlog2(9) will give 3 << 24 + ... = 3.16... * 2^24 * * intlog2(1.5) = intlog2(3) - 2^24 = 0.584... * 2^24 * * * return: log2(value) * 2^24 */ extern unsigned int intlog2(u32 value); /** * intlog10 - computes log10 of a value; the result is shifted left by 24 bits * * @value: The value (must be != 0) * * to use rational values you can use the following method: * * intlog10(value) = intlog10(value * 10^x) - x * 2^24 * * An usecase example: * * intlog10(1000) will give 3 << 24 = 3 * 2^24 * * due to the implementation intlog10(1000) might be not exactly 3 * 2^24 * * look at intlog2 for similar examples * * return: log10(value) * 2^24 */ extern unsigned int intlog10(u32 value); #endif