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git.proxmox.com Git - mirror_ubuntu-artful-kernel.git/blob - drivers/media/dvb-core/dvb_math.h
2 * dvb-math provides some complex fixed-point math
3 * operations shared between the dvb related stuff
5 * Copyright (C) 2006 Christoph Pfister (christophpfister@gmail.com)
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.
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.
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
25 #include <linux/types.h>
28 * computes log2 of a value; the result is shifted left by 24 bits
30 * to use rational values you can use the following method:
31 * intlog2(value) = intlog2(value * 2^x) - x * 2^24
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
37 * @param value The value (must be != 0)
38 * @return log2(value) * 2^24
40 extern unsigned int intlog2(u32 value
);
43 * computes log10 of a value; the result is shifted left by 24 bits
45 * to use rational values you can use the following method:
46 * intlog10(value) = intlog10(value * 10^x) - x * 2^24
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
51 * look at intlog2 for similar examples
53 * @param value The value (must be != 0)
54 * @return log10(value) * 2^24
56 extern unsigned int intlog10(u32 value
);