/* 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. You should have received a copy of the GNU Lesser General Public License along with this library; if not, write to the Free Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA */ #ifndef DVB_MATH_H #define DVB_MATH_H /** * computes log2 of a value; the result is shifted left by 16 bits * * to use rational values you can use the following method: * intlog2(value) = intlog2(value * 2^x) - x * 2^16 * * example: intlog2(8) will give 3 << 16 = 3 * 2^16 = 196608 * example: intlog2(9) will give 3 << 16 + ... = 207744 (rounded) * example: intlog2(1.5) = intlog2(3) - 2^16 = 38336 (rounded) * * @param value The value [ 0 gives a wrong result ] * @return log2(value) * 2^16 */ extern unsigned int intlog2(unsigned int value); /** * computes log10 of a value; the result is shifted left by 28 bits * * to use rational values you can use the following method: * intlog10(value) = intlog10(value * 10^x) - x * 2^28 * * example: intlog10(1000) will give 3 << 28 = 3 * 2^28 * due to the implementation intlog10(1000) might be not exactly 3 * 2^28 * * look at intlog2 for similar examples * * @param value The value [ 0 gives a wrong result ] * @return log10(value) * 2^28 */ extern unsigned int intlog10(unsigned int value); #endif