1/* 2 * dvb-math provides some complex fixed-point math 3 * operations shared between the dvb related stuff 4 * 5 * Copyright (C) 2006 Christoph Pfister (christophpfister@gmail.com) 6 * 7 * This library is free software; you can redistribute it and/or modify 8 * it under the terms of the GNU Lesser General Public License as 9 * published by the Free Software Foundation; either version 2.1 of 10 * the License, or (at your option) any later version. 11 * 12 * This program is distributed in the hope that it will be useful, 13 * but WITHOUT ANY WARRANTY; without even the implied warranty of 14 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the 15 * GNU Lesser General Public License for more details. 16 * 17 * You should have received a copy of the GNU Lesser General Public 18 * License along with this library; if not, write to the Free Software 19 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA 20 */ 21 22#ifndef __DVB_MATH_H 23#define __DVB_MATH_H 24 25#include <linux/types.h> 26 27/** 28 * computes log2 of a value; the result is shifted left by 24 bits 29 * 30 * to use rational values you can use the following method: 31 * intlog2(value) = intlog2(value * 2^x) - x * 2^24 32 * 33 * example: intlog2(8) will give 3 << 24 = 3 * 2^24 34 * example: intlog2(9) will give 3 << 24 + ... = 3.16... * 2^24 35 * example: intlog2(1.5) = intlog2(3) - 2^24 = 0.584... * 2^24 36 * 37 * @param value The value (must be != 0) 38 * @return log2(value) * 2^24 39 */ 40extern unsigned int intlog2(u32 value); 41 42/** 43 * computes log10 of a value; the result is shifted left by 24 bits 44 * 45 * to use rational values you can use the following method: 46 * intlog10(value) = intlog10(value * 10^x) - x * 2^24 47 * 48 * example: intlog10(1000) will give 3 << 24 = 3 * 2^24 49 * due to the implementation intlog10(1000) might be not exactly 3 * 2^24 50 * 51 * look at intlog2 for similar examples 52 * 53 * @param value The value (must be != 0) 54 * @return log10(value) * 2^24 55 */ 56extern unsigned int intlog10(u32 value); 57 58#endif 59