forked from mirrors/linux
9ab04d7ed8
Replace license boilerplate in udftime.c with SPDX identifier for LGPL-2.1-or-later. Acked-by: Mauro Carvalho Chehab <mchehab@kernel.org> Link: https://lore.kernel.org/r/20230619172019.21457-4-andriy.shevchenko@linux.intel.com Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com> Link: https://lore.kernel.org/r/20230703135211.87416-4-andriy.shevchenko@linux.intel.com Signed-off-by: Mark Brown <broonie@kernel.org>
56 lines
1.3 KiB
C
56 lines
1.3 KiB
C
/* SPDX-License-Identifier: LGPL-2.1-or-later */
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/*
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* Provides fixed-point logarithm operations.
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*
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* Copyright (C) 2006 Christoph Pfister (christophpfister@gmail.com)
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*/
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#ifndef __LINUX_INT_LOG_H
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#define __LINUX_INT_LOG_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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