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1/* ******************************************************************2 * hist : Histogram functions3 * part of Finite State Entropy project4 * Copyright (c) Yann Collet, Facebook, Inc.5 *6 * You can contact the author at :7 * - FSE source repository : https://github.com/Cyan4973/FiniteStateEntropy8 * - Public forum : https://groups.google.com/forum/#!forum/lz4c9 *10 * This source code is licensed under both the BSD-style license (found in the11 * LICENSE file in the root directory of this source tree) and the GPLv2 (found12 * in the COPYING file in the root directory of this source tree).13 * You may select, at your option, one of the above-listed licenses.14****************************************************************** */15 16/* --- dependencies --- */17#include "../common/zstd_deps.h" /* size_t */18 19 20/* --- simple histogram functions --- */21 22/*! HIST_count():23 * Provides the precise count of each byte within a table 'count'.24 * 'count' is a table of unsigned int, of minimum size (*maxSymbolValuePtr+1).25 * Updates *maxSymbolValuePtr with actual largest symbol value detected.26 * @return : count of the most frequent symbol (which isn't identified).27 * or an error code, which can be tested using HIST_isError().28 * note : if return == srcSize, there is only one symbol.29 */30size_t HIST_count(unsigned* count, unsigned* maxSymbolValuePtr,31 const void* src, size_t srcSize);32 33unsigned HIST_isError(size_t code); /*< tells if a return value is an error code */34 35 36/* --- advanced histogram functions --- */37 38#define HIST_WKSP_SIZE_U32 102439#define HIST_WKSP_SIZE (HIST_WKSP_SIZE_U32 * sizeof(unsigned))40/* HIST_count_wksp() :41 * Same as HIST_count(), but using an externally provided scratch buffer.42 * Benefit is this function will use very little stack space.43 * `workSpace` is a writable buffer which must be 4-bytes aligned,44 * `workSpaceSize` must be >= HIST_WKSP_SIZE45 */46size_t HIST_count_wksp(unsigned* count, unsigned* maxSymbolValuePtr,47 const void* src, size_t srcSize,48 void* workSpace, size_t workSpaceSize);49 50/* HIST_countFast() :51 * same as HIST_count(), but blindly trusts that all byte values within src are <= *maxSymbolValuePtr.52 * This function is unsafe, and will segfault if any value within `src` is `> *maxSymbolValuePtr`53 */54size_t HIST_countFast(unsigned* count, unsigned* maxSymbolValuePtr,55 const void* src, size_t srcSize);56 57/* HIST_countFast_wksp() :58 * Same as HIST_countFast(), but using an externally provided scratch buffer.59 * `workSpace` is a writable buffer which must be 4-bytes aligned,60 * `workSpaceSize` must be >= HIST_WKSP_SIZE61 */62size_t HIST_countFast_wksp(unsigned* count, unsigned* maxSymbolValuePtr,63 const void* src, size_t srcSize,64 void* workSpace, size_t workSpaceSize);65 66/*! HIST_count_simple() :67 * Same as HIST_countFast(), this function is unsafe,68 * and will segfault if any value within `src` is `> *maxSymbolValuePtr`.69 * It is also a bit slower for large inputs.70 * However, it does not need any additional memory (not even on stack).71 * @return : count of the most frequent symbol.72 * Note this function doesn't produce any error (i.e. it must succeed).73 */74unsigned HIST_count_simple(unsigned* count, unsigned* maxSymbolValuePtr,75 const void* src, size_t srcSize);76