diff options
author | Christoph Pfister <christophpfister@bluemail.ch> | 2006-05-22 10:32:04 -0300 |
---|---|---|
committer | Mauro Carvalho Chehab <mchehab@infradead.org> | 2006-06-25 02:00:08 -0300 |
commit | da22d0e758bf011be5921421bf490ce69c387784 (patch) | |
tree | 87923892b62d43df67913d50ecb3424a8ee2facd /drivers/media/dvb/dvb-core/dvb_math.h | |
parent | 5c1208ba457a1668c81868060c08496a2d053be0 (diff) | |
download | op-kernel-dev-da22d0e758bf011be5921421bf490ce69c387784.zip op-kernel-dev-da22d0e758bf011be5921421bf490ce69c387784.tar.gz |
V4L/DVB (3988): Add math routines required by DVB demods
Signed-off-by: Christoph Pfister <christophpfister@bluemail.ch>
Signed-off-by: Manu Abraham <manu@linuxtv.org>
Signed-off-by: Mauro Carvalho Chehab <mchehab@infradead.org>
Diffstat (limited to 'drivers/media/dvb/dvb-core/dvb_math.h')
-rw-r--r-- | drivers/media/dvb/dvb-core/dvb_math.h | 58 |
1 files changed, 58 insertions, 0 deletions
diff --git a/drivers/media/dvb/dvb-core/dvb_math.h b/drivers/media/dvb/dvb-core/dvb_math.h new file mode 100644 index 0000000..aecc867 --- /dev/null +++ b/drivers/media/dvb/dvb-core/dvb_math.h @@ -0,0 +1,58 @@ +/* + * 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 |