Mercurial > hgrepos > Python2 > PyMuPDF
diff mupdf-source/thirdparty/brotli/c/enc/fast_log.h @ 2:b50eed0cc0ef upstream
ADD: MuPDF v1.26.7: the MuPDF source as downloaded by a default build of PyMuPDF 1.26.4.
The directory name has changed: no version number in the expanded directory now.
| author | Franz Glasner <fzglas.hg@dom66.de> |
|---|---|
| date | Mon, 15 Sep 2025 11:43:07 +0200 |
| parents | |
| children |
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--- /dev/null Thu Jan 01 00:00:00 1970 +0000 +++ b/mupdf-source/thirdparty/brotli/c/enc/fast_log.h Mon Sep 15 11:43:07 2025 +0200 @@ -0,0 +1,67 @@ +/* Copyright 2013 Google Inc. All Rights Reserved. + + Distributed under MIT license. + See file LICENSE for detail or copy at https://opensource.org/licenses/MIT +*/ + +/* Utilities for fast computation of logarithms. */ + +#ifndef BROTLI_ENC_FAST_LOG_H_ +#define BROTLI_ENC_FAST_LOG_H_ + +#include <math.h> + +#include <brotli/types.h> + +#include "../common/platform.h" + +#if defined(__cplusplus) || defined(c_plusplus) +extern "C" { +#endif + +static BROTLI_INLINE uint32_t Log2FloorNonZero(size_t n) { +#if defined(BROTLI_BSR32) + return BROTLI_BSR32((uint32_t)n); +#else + uint32_t result = 0; + while (n >>= 1) result++; + return result; +#endif +} + +#define BROTLI_LOG2_TABLE_SIZE 256 + +/* A lookup table for small values of log2(int) to be used in entropy + computation. */ +BROTLI_INTERNAL extern const double kBrotliLog2Table[BROTLI_LOG2_TABLE_SIZE]; + +/* Visual Studio 2012 and Android API levels < 18 do not have the log2() + * function defined, so we use log() and a multiplication instead. */ +#if !defined(BROTLI_HAVE_LOG2) +#if ((defined(_MSC_VER) && _MSC_VER <= 1700) || \ + (defined(__ANDROID_API__) && __ANDROID_API__ < 18)) +#define BROTLI_HAVE_LOG2 0 +#else +#define BROTLI_HAVE_LOG2 1 +#endif +#endif + +#define LOG_2_INV 1.4426950408889634 + +/* Faster logarithm for small integers, with the property of log2(0) == 0. */ +static BROTLI_INLINE double FastLog2(size_t v) { + if (v < BROTLI_LOG2_TABLE_SIZE) { + return kBrotliLog2Table[v]; + } +#if !(BROTLI_HAVE_LOG2) + return log((double)v) * LOG_2_INV; +#else + return log2((double)v); +#endif +} + +#if defined(__cplusplus) || defined(c_plusplus) +} /* extern "C" */ +#endif + +#endif /* BROTLI_ENC_FAST_LOG_H_ */
