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66 lines
1.8 KiB
66 lines
1.8 KiB
/* |
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* dvb-math provides some complex fixed-point math |
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* operations shared between the dvb related stuff |
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* |
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* Copyright (C) 2006 Christoph Pfister ([email protected]) |
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* |
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* This library is free software; you can redistribute it and/or modify |
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* it under the terms of the GNU Lesser General Public License as |
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* published by the Free Software Foundation; either version 2.1 of |
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* the License, or (at your option) any later version. |
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* |
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* This program is distributed in the hope that it will be useful, |
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* but WITHOUT ANY WARRANTY; without even the implied warranty of |
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the |
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* GNU Lesser General Public License for more details. |
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*/ |
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#ifndef __DVB_MATH_H |
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#define __DVB_MATH_H |
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#include <linux/types.h> |
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/** |
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* intlog2 - computes log2 of a value; the result is shifted left by 24 bits |
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* |
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* @value: The value (must be != 0) |
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* |
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* to use rational values you can use the following method: |
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* |
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* intlog2(value) = intlog2(value * 2^x) - x * 2^24 |
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* |
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* Some usecase examples: |
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* |
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* intlog2(8) will give 3 << 24 = 3 * 2^24 |
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* |
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* intlog2(9) will give 3 << 24 + ... = 3.16... * 2^24 |
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* |
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* intlog2(1.5) = intlog2(3) - 2^24 = 0.584... * 2^24 |
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* |
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* |
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* return: log2(value) * 2^24 |
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*/ |
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extern unsigned int intlog2(u32 value); |
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/** |
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* intlog10 - computes log10 of a value; the result is shifted left by 24 bits |
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* |
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* @value: The value (must be != 0) |
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* |
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* to use rational values you can use the following method: |
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* |
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* intlog10(value) = intlog10(value * 10^x) - x * 2^24 |
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* |
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* An usecase example: |
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* |
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* intlog10(1000) will give 3 << 24 = 3 * 2^24 |
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* |
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* due to the implementation intlog10(1000) might be not exactly 3 * 2^24 |
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* |
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* look at intlog2 for similar examples |
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* |
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* return: log10(value) * 2^24 |
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*/ |
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extern unsigned int intlog10(u32 value); |
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#endif
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