관리-도구

편집 파일: int_log.h

/* SPDX-License-Identifier: LGPL-2.1-or-later */ /* * Provides fixed-point logarithm operations. * * Copyright (C) 2006 Christoph Pfister (christophpfister@gmail.com) */ #ifndef __LINUX_INT_LOG_H #define __LINUX_INT_LOG_H #include <linux/types.h> /** * intlog2 - computes log2 of a value; the result is shifted left by 24 bits * * @value: The value (must be != 0) * * to use rational values you can use the following method: * * intlog2(value) = intlog2(value * 2^x) - x * 2^24 * * Some usecase examples: * * intlog2(8) will give 3 << 24 = 3 * 2^24 * * intlog2(9) will give 3 << 24 + ... = 3.16... * 2^24 * * intlog2(1.5) = intlog2(3) - 2^24 = 0.584... * 2^24 * * * return: log2(value) * 2^24 */ extern unsigned int intlog2(u32 value); /** * intlog10 - computes log10 of a value; the result is shifted left by 24 bits * * @value: The value (must be != 0) * * to use rational values you can use the following method: * * intlog10(value) = intlog10(value * 10^x) - x * 2^24 * * An usecase 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 * * return: log10(value) * 2^24 */ extern unsigned int intlog10(u32 value); #endif