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author | Daniel Baumann <daniel.baumann@progress-linux.org> | 2024-04-11 08:27:49 +0000 |
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committer | Daniel Baumann <daniel.baumann@progress-linux.org> | 2024-04-11 08:27:49 +0000 |
commit | ace9429bb58fd418f0c81d4c2835699bddf6bde6 (patch) | |
tree | b2d64bc10158fdd5497876388cd68142ca374ed3 /lib/zstd/compress/hist.h | |
parent | Initial commit. (diff) | |
download | linux-ace9429bb58fd418f0c81d4c2835699bddf6bde6.tar.xz linux-ace9429bb58fd418f0c81d4c2835699bddf6bde6.zip |
Adding upstream version 6.6.15.upstream/6.6.15
Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>
Diffstat (limited to '')
-rw-r--r-- | lib/zstd/compress/hist.h | 75 |
1 files changed, 75 insertions, 0 deletions
diff --git a/lib/zstd/compress/hist.h b/lib/zstd/compress/hist.h new file mode 100644 index 0000000000..fc1830abc9 --- /dev/null +++ b/lib/zstd/compress/hist.h @@ -0,0 +1,75 @@ +/* ****************************************************************** + * hist : Histogram functions + * part of Finite State Entropy project + * Copyright (c) Yann Collet, Facebook, Inc. + * + * You can contact the author at : + * - FSE source repository : https://github.com/Cyan4973/FiniteStateEntropy + * - Public forum : https://groups.google.com/forum/#!forum/lz4c + * + * This source code is licensed under both the BSD-style license (found in the + * LICENSE file in the root directory of this source tree) and the GPLv2 (found + * in the COPYING file in the root directory of this source tree). + * You may select, at your option, one of the above-listed licenses. +****************************************************************** */ + +/* --- dependencies --- */ +#include "../common/zstd_deps.h" /* size_t */ + + +/* --- simple histogram functions --- */ + +/*! HIST_count(): + * Provides the precise count of each byte within a table 'count'. + * 'count' is a table of unsigned int, of minimum size (*maxSymbolValuePtr+1). + * Updates *maxSymbolValuePtr with actual largest symbol value detected. + * @return : count of the most frequent symbol (which isn't identified). + * or an error code, which can be tested using HIST_isError(). + * note : if return == srcSize, there is only one symbol. + */ +size_t HIST_count(unsigned* count, unsigned* maxSymbolValuePtr, + const void* src, size_t srcSize); + +unsigned HIST_isError(size_t code); /*< tells if a return value is an error code */ + + +/* --- advanced histogram functions --- */ + +#define HIST_WKSP_SIZE_U32 1024 +#define HIST_WKSP_SIZE (HIST_WKSP_SIZE_U32 * sizeof(unsigned)) +/* HIST_count_wksp() : + * Same as HIST_count(), but using an externally provided scratch buffer. + * Benefit is this function will use very little stack space. + * `workSpace` is a writable buffer which must be 4-bytes aligned, + * `workSpaceSize` must be >= HIST_WKSP_SIZE + */ +size_t HIST_count_wksp(unsigned* count, unsigned* maxSymbolValuePtr, + const void* src, size_t srcSize, + void* workSpace, size_t workSpaceSize); + +/* HIST_countFast() : + * same as HIST_count(), but blindly trusts that all byte values within src are <= *maxSymbolValuePtr. + * This function is unsafe, and will segfault if any value within `src` is `> *maxSymbolValuePtr` + */ +size_t HIST_countFast(unsigned* count, unsigned* maxSymbolValuePtr, + const void* src, size_t srcSize); + +/* HIST_countFast_wksp() : + * Same as HIST_countFast(), but using an externally provided scratch buffer. + * `workSpace` is a writable buffer which must be 4-bytes aligned, + * `workSpaceSize` must be >= HIST_WKSP_SIZE + */ +size_t HIST_countFast_wksp(unsigned* count, unsigned* maxSymbolValuePtr, + const void* src, size_t srcSize, + void* workSpace, size_t workSpaceSize); + +/*! HIST_count_simple() : + * Same as HIST_countFast(), this function is unsafe, + * and will segfault if any value within `src` is `> *maxSymbolValuePtr`. + * It is also a bit slower for large inputs. + * However, it does not need any additional memory (not even on stack). + * @return : count of the most frequent symbol. + * Note this function doesn't produce any error (i.e. it must succeed). + */ +unsigned HIST_count_simple(unsigned* count, unsigned* maxSymbolValuePtr, + const void* src, size_t srcSize); |