From e6918187568dbd01842d8d1d2c808ce16a894239 Mon Sep 17 00:00:00 2001 From: Daniel Baumann Date: Sun, 21 Apr 2024 13:54:28 +0200 Subject: Adding upstream version 18.2.2. Signed-off-by: Daniel Baumann --- src/zstd/lib/compress/hist.c | 183 +++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 183 insertions(+) create mode 100644 src/zstd/lib/compress/hist.c (limited to 'src/zstd/lib/compress/hist.c') diff --git a/src/zstd/lib/compress/hist.c b/src/zstd/lib/compress/hist.c new file mode 100644 index 000000000..61e08c796 --- /dev/null +++ b/src/zstd/lib/compress/hist.c @@ -0,0 +1,183 @@ +/* ****************************************************************** + * hist : Histogram functions + * part of Finite State Entropy project + * Copyright (c) 2013-2020, 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/mem.h" /* U32, BYTE, etc. */ +#include "../common/debug.h" /* assert, DEBUGLOG */ +#include "../common/error_private.h" /* ERROR */ +#include "hist.h" + + +/* --- Error management --- */ +unsigned HIST_isError(size_t code) { return ERR_isError(code); } + +/*-************************************************************** + * Histogram functions + ****************************************************************/ +unsigned HIST_count_simple(unsigned* count, unsigned* maxSymbolValuePtr, + const void* src, size_t srcSize) +{ + const BYTE* ip = (const BYTE*)src; + const BYTE* const end = ip + srcSize; + unsigned maxSymbolValue = *maxSymbolValuePtr; + unsigned largestCount=0; + + memset(count, 0, (maxSymbolValue+1) * sizeof(*count)); + if (srcSize==0) { *maxSymbolValuePtr = 0; return 0; } + + while (ip largestCount) largestCount = count[s]; + } + + return largestCount; +} + +typedef enum { trustInput, checkMaxSymbolValue } HIST_checkInput_e; + +/* HIST_count_parallel_wksp() : + * store histogram into 4 intermediate tables, recombined at the end. + * this design makes better use of OoO cpus, + * and is noticeably faster when some values are heavily repeated. + * But it needs some additional workspace for intermediate tables. + * `workSpace` size must be a table of size >= HIST_WKSP_SIZE_U32. + * @return : largest histogram frequency, + * or an error code (notably when histogram would be larger than *maxSymbolValuePtr). */ +static size_t HIST_count_parallel_wksp( + unsigned* count, unsigned* maxSymbolValuePtr, + const void* source, size_t sourceSize, + HIST_checkInput_e check, + U32* const workSpace) +{ + const BYTE* ip = (const BYTE*)source; + const BYTE* const iend = ip+sourceSize; + unsigned maxSymbolValue = *maxSymbolValuePtr; + unsigned max=0; + U32* const Counting1 = workSpace; + U32* const Counting2 = Counting1 + 256; + U32* const Counting3 = Counting2 + 256; + U32* const Counting4 = Counting3 + 256; + + memset(workSpace, 0, 4*256*sizeof(unsigned)); + + /* safety checks */ + if (!sourceSize) { + memset(count, 0, maxSymbolValue + 1); + *maxSymbolValuePtr = 0; + return 0; + } + if (!maxSymbolValue) maxSymbolValue = 255; /* 0 == default */ + + /* by stripes of 16 bytes */ + { U32 cached = MEM_read32(ip); ip += 4; + while (ip < iend-15) { + U32 c = cached; cached = MEM_read32(ip); ip += 4; + Counting1[(BYTE) c ]++; + Counting2[(BYTE)(c>>8) ]++; + Counting3[(BYTE)(c>>16)]++; + Counting4[ c>>24 ]++; + c = cached; cached = MEM_read32(ip); ip += 4; + Counting1[(BYTE) c ]++; + Counting2[(BYTE)(c>>8) ]++; + Counting3[(BYTE)(c>>16)]++; + Counting4[ c>>24 ]++; + c = cached; cached = MEM_read32(ip); ip += 4; + Counting1[(BYTE) c ]++; + Counting2[(BYTE)(c>>8) ]++; + Counting3[(BYTE)(c>>16)]++; + Counting4[ c>>24 ]++; + c = cached; cached = MEM_read32(ip); ip += 4; + Counting1[(BYTE) c ]++; + Counting2[(BYTE)(c>>8) ]++; + Counting3[(BYTE)(c>>16)]++; + Counting4[ c>>24 ]++; + } + ip-=4; + } + + /* finish last symbols */ + while (ipmaxSymbolValue; s--) { + Counting1[s] += Counting2[s] + Counting3[s] + Counting4[s]; + if (Counting1[s]) return ERROR(maxSymbolValue_tooSmall); + } } + + { U32 s; + if (maxSymbolValue > 255) maxSymbolValue = 255; + for (s=0; s<=maxSymbolValue; s++) { + count[s] = Counting1[s] + Counting2[s] + Counting3[s] + Counting4[s]; + if (count[s] > max) max = count[s]; + } } + + while (!count[maxSymbolValue]) maxSymbolValue--; + *maxSymbolValuePtr = maxSymbolValue; + return (size_t)max; +} + +/* 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* source, size_t sourceSize, + void* workSpace, size_t workSpaceSize) +{ + if (sourceSize < 1500) /* heuristic threshold */ + return HIST_count_simple(count, maxSymbolValuePtr, source, sourceSize); + if ((size_t)workSpace & 3) return ERROR(GENERIC); /* must be aligned on 4-bytes boundaries */ + if (workSpaceSize < HIST_WKSP_SIZE) return ERROR(workSpace_tooSmall); + return HIST_count_parallel_wksp(count, maxSymbolValuePtr, source, sourceSize, trustInput, (U32*)workSpace); +} + +/* fast variant (unsafe : won't check if src contains values beyond count[] limit) */ +size_t HIST_countFast(unsigned* count, unsigned* maxSymbolValuePtr, + const void* source, size_t sourceSize) +{ + unsigned tmpCounters[HIST_WKSP_SIZE_U32]; + return HIST_countFast_wksp(count, maxSymbolValuePtr, source, sourceSize, tmpCounters, sizeof(tmpCounters)); +} + +/* HIST_count_wksp() : + * Same as HIST_count(), but using an externally provided scratch buffer. + * `workSpace` size must be table of >= HIST_WKSP_SIZE_U32 unsigned */ +size_t HIST_count_wksp(unsigned* count, unsigned* maxSymbolValuePtr, + const void* source, size_t sourceSize, + void* workSpace, size_t workSpaceSize) +{ + if ((size_t)workSpace & 3) return ERROR(GENERIC); /* must be aligned on 4-bytes boundaries */ + if (workSpaceSize < HIST_WKSP_SIZE) return ERROR(workSpace_tooSmall); + if (*maxSymbolValuePtr < 255) + return HIST_count_parallel_wksp(count, maxSymbolValuePtr, source, sourceSize, checkMaxSymbolValue, (U32*)workSpace); + *maxSymbolValuePtr = 255; + return HIST_countFast_wksp(count, maxSymbolValuePtr, source, sourceSize, workSpace, workSpaceSize); +} + +size_t HIST_count(unsigned* count, unsigned* maxSymbolValuePtr, + const void* src, size_t srcSize) +{ + unsigned tmpCounters[HIST_WKSP_SIZE_U32]; + return HIST_count_wksp(count, maxSymbolValuePtr, src, srcSize, tmpCounters, sizeof(tmpCounters)); +} -- cgit v1.2.3