| 1 |
|
| 2 | |
| 3 | * hist : Histogram functions
|
| 4 | * part of Finite State Entropy project
|
| 5 | * Copyright (c) Meta Platforms, Inc. and affiliates.
|
| 6 | *
|
| 7 | * You can contact the author at :
|
| 8 | * - FSE source repository : https://github.com/Cyan4973/FiniteStateEntropy
|
| 9 | * - Public forum : https://groups.google.com/forum/#!forum/lz4c
|
| 10 | *
|
| 11 | * This source code is licensed under both the BSD-style license (found in the
|
| 12 | * LICENSE file in the root directory of this source tree) and the GPLv2 (found
|
| 13 | * in the COPYING file in the root directory of this source tree).
|
| 14 | * You may select, at your option, one of the above-listed licenses.
|
| 15 | ******************************************************************
|
| 16 |
|
| 17 |
|
| 18 | #include "../common/zstd_deps.h"
|
| 19 |
|
| 20 |
|
| 21 |
|
| 22 |
|
| 23 | |
| 24 | * Provides the precise count of each byte within a table 'count'.
|
| 25 | * 'count' is a table of unsigned int, of minimum size (*maxSymbolValuePtr+1).
|
| 26 | * Updates *maxSymbolValuePtr with actual largest symbol value detected.
|
| 27 | * @return : count of the most frequent symbol (which isn't identified).
|
| 28 | * or an error code, which can be tested using HIST_isError().
|
| 29 | * note : if return == srcSize, there is only one symbol.
|
| 30 |
|
| 31 | size_t HIST_count(unsigned* count, unsigned* maxSymbolValuePtr,
|
| 32 | const void* src, size_t srcSize);
|
| 33 |
|
| 34 | unsigned HIST_isError(size_t code);
|
| 35 |
|
| 36 |
|
| 37 |
|
| 38 |
|
| 39 | #define HIST_WKSP_SIZE_U32 1024
|
| 40 | #define HIST_WKSP_SIZE (HIST_WKSP_SIZE_U32 * sizeof(unsigned))
|
| 41 | |
| 42 | * Same as HIST_count(), but using an externally provided scratch buffer.
|
| 43 | * Benefit is this function will use very little stack space.
|
| 44 | * `workSpace` is a writable buffer which must be 4-bytes aligned,
|
| 45 | * `workSpaceSize` must be >= HIST_WKSP_SIZE
|
| 46 |
|
| 47 | size_t HIST_count_wksp(unsigned* count, unsigned* maxSymbolValuePtr,
|
| 48 | const void* src, size_t srcSize,
|
| 49 | void* workSpace, size_t workSpaceSize);
|
| 50 |
|
| 51 | |
| 52 | * same as HIST_count(), but blindly trusts that all byte values within src are <= *maxSymbolValuePtr.
|
| 53 | * This function is unsafe, and will segfault if any value within `src` is `> *maxSymbolValuePtr`
|
| 54 |
|
| 55 | size_t HIST_countFast(unsigned* count, unsigned* maxSymbolValuePtr,
|
| 56 | const void* src, size_t srcSize);
|
| 57 |
|
| 58 | |
| 59 | * Same as HIST_countFast(), but using an externally provided scratch buffer.
|
| 60 | * `workSpace` is a writable buffer which must be 4-bytes aligned,
|
| 61 | * `workSpaceSize` must be >= HIST_WKSP_SIZE
|
| 62 |
|
| 63 | size_t HIST_countFast_wksp(unsigned* count, unsigned* maxSymbolValuePtr,
|
| 64 | const void* src, size_t srcSize,
|
| 65 | void* workSpace, size_t workSpaceSize);
|
| 66 |
|
| 67 | |
| 68 | * Same as HIST_countFast(), this function is unsafe,
|
| 69 | * and will segfault if any value within `src` is `> *maxSymbolValuePtr`.
|
| 70 | * It is also a bit slower for large inputs.
|
| 71 | * However, it does not need any additional memory (not even on stack).
|
| 72 | * @return : count of the most frequent symbol.
|
| 73 | * Note this function doesn't produce any error (i.e. it must succeed).
|
| 74 |
|
| 75 | unsigned HIST_count_simple(unsigned* count, unsigned* maxSymbolValuePtr,
|
| 76 | const void* src, size_t srcSize);
|
| 77 |
|
| 78 | |
| 79 | * Lowest level: just add nb of occurrences of characters from @src into @count.
|
| 80 | * @count is not reset. @count array is presumed large enough (i.e. 1 KB).
|
| 81 | @ This function does not need any additional stack memory.
|
| 82 |
|
| 83 | void HIST_add(unsigned* count, const void* src, size_t srcSize);
|