59 строки
1.9 KiB
C
59 строки
1.9 KiB
C
/*
|
|
* 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
|
|
|
|
#include <linux/types.h>
|
|
|
|
/**
|
|
* computes log2 of a value; the result is shifted left by 24 bits
|
|
*
|
|
* to use rational values you can use the following method:
|
|
* intlog2(value) = intlog2(value * 2^x) - x * 2^24
|
|
*
|
|
* example: intlog2(8) will give 3 << 24 = 3 * 2^24
|
|
* example: intlog2(9) will give 3 << 24 + ... = 3.16... * 2^24
|
|
* example: intlog2(1.5) = intlog2(3) - 2^24 = 0.584... * 2^24
|
|
*
|
|
* @param value The value (must be != 0)
|
|
* @return log2(value) * 2^24
|
|
*/
|
|
extern unsigned int intlog2(u32 value);
|
|
|
|
/**
|
|
* computes log10 of a value; the result is shifted left by 24 bits
|
|
*
|
|
* to use rational values you can use the following method:
|
|
* intlog10(value) = intlog10(value * 10^x) - x * 2^24
|
|
*
|
|
* 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
|
|
*
|
|
* @param value The value (must be != 0)
|
|
* @return log10(value) * 2^24
|
|
*/
|
|
extern unsigned int intlog10(u32 value);
|
|
|
|
#endif
|