cachepc-linux

Fork of AMDESE/linux with modifications for CachePC side-channel attack
git clone https://git.sinitax.com/sinitax/cachepc-linux
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hist.h (3435B)


      1/* ******************************************************************
      2 * hist : Histogram functions
      3 * part of Finite State Entropy project
      4 * Copyright (c) Yann Collet, Facebook, Inc.
      5 *
      6 *  You can contact the author at :
      7 *  - FSE source repository : https://github.com/Cyan4973/FiniteStateEntropy
      8 *  - Public forum : https://groups.google.com/forum/#!forum/lz4c
      9 *
     10 * This source code is licensed under both the BSD-style license (found in the
     11 * LICENSE file in the root directory of this source tree) and the GPLv2 (found
     12 * 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 1024
     39#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_SIZE
     45 */
     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_SIZE
     61 */
     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);