blob: 8690ec42954d03bae4b2c65871c887bc26a1ee79 (
plain) (
tree)
|
|
/*
* 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 <linux/types.h>
/**
* 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
|
