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Diffstat (limited to '')
| -rw-r--r-- | lib/zstd/entropy_common.c | 243 |
1 files changed, 243 insertions, 0 deletions
diff --git a/lib/zstd/entropy_common.c b/lib/zstd/entropy_common.c new file mode 100644 index 000000000..2b0a643c3 --- /dev/null +++ b/lib/zstd/entropy_common.c @@ -0,0 +1,243 @@ +/* + * Common functions of New Generation Entropy library + * Copyright (C) 2016, Yann Collet. + * + * BSD 2-Clause License (http://www.opensource.org/licenses/bsd-license.php) + * + * Redistribution and use in source and binary forms, with or without + * modification, are permitted provided that the following conditions are + * met: + * + * * Redistributions of source code must retain the above copyright + * notice, this list of conditions and the following disclaimer. + * * Redistributions in binary form must reproduce the above + * copyright notice, this list of conditions and the following disclaimer + * in the documentation and/or other materials provided with the + * distribution. + * + * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS + * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT + * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR + * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT + * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, + * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT + * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, + * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY + * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT + * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE + * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. + * + * This program is free software; you can redistribute it and/or modify it under + * the terms of the GNU General Public License version 2 as published by the + * Free Software Foundation. This program is dual-licensed; you may select + * either version 2 of the GNU General Public License ("GPL") or BSD license + * ("BSD"). + * + * You can contact the author at : + * - Source repository : https://github.com/Cyan4973/FiniteStateEntropy + */ + +/* ************************************* +* Dependencies +***************************************/ +#include "error_private.h" /* ERR_*, ERROR */ +#include "fse.h" +#include "huf.h" +#include "mem.h" + +/*=== Version ===*/ +unsigned FSE_versionNumber(void) { return FSE_VERSION_NUMBER; } + +/*=== Error Management ===*/ +unsigned FSE_isError(size_t code) { return ERR_isError(code); } + +unsigned HUF_isError(size_t code) { return ERR_isError(code); } + +/*-************************************************************** +* FSE NCount encoding-decoding +****************************************************************/ +size_t FSE_readNCount(short *normalizedCounter, unsigned *maxSVPtr, unsigned *tableLogPtr, const void *headerBuffer, size_t hbSize) +{ + const BYTE *const istart = (const BYTE *)headerBuffer; + const BYTE *const iend = istart + hbSize; + const BYTE *ip = istart; + int nbBits; + int remaining; + int threshold; + U32 bitStream; + int bitCount; + unsigned charnum = 0; + int previous0 = 0; + + if (hbSize < 4) + return ERROR(srcSize_wrong); + bitStream = ZSTD_readLE32(ip); + nbBits = (bitStream & 0xF) + FSE_MIN_TABLELOG; /* extract tableLog */ + if (nbBits > FSE_TABLELOG_ABSOLUTE_MAX) + return ERROR(tableLog_tooLarge); + bitStream >>= 4; + bitCount = 4; + *tableLogPtr = nbBits; + remaining = (1 << nbBits) + 1; + threshold = 1 << nbBits; + nbBits++; + + while ((remaining > 1) & (charnum <= *maxSVPtr)) { + if (previous0) { + unsigned n0 = charnum; + while ((bitStream & 0xFFFF) == 0xFFFF) { + n0 += 24; + if (ip < iend - 5) { + ip += 2; + bitStream = ZSTD_readLE32(ip) >> bitCount; + } else { + bitStream >>= 16; + bitCount += 16; + } + } + while ((bitStream & 3) == 3) { + n0 += 3; + bitStream >>= 2; + bitCount += 2; + } + n0 += bitStream & 3; + bitCount += 2; + if (n0 > *maxSVPtr) + return ERROR(maxSymbolValue_tooSmall); + while (charnum < n0) + normalizedCounter[charnum++] = 0; + if ((ip <= iend - 7) || (ip + (bitCount >> 3) <= iend - 4)) { + ip += bitCount >> 3; + bitCount &= 7; + bitStream = ZSTD_readLE32(ip) >> bitCount; + } else { + bitStream >>= 2; + } + } + { + int const max = (2 * threshold - 1) - remaining; + int count; + + if ((bitStream & (threshold - 1)) < (U32)max) { + count = bitStream & (threshold - 1); + bitCount += nbBits - 1; + } else { + count = bitStream & (2 * threshold - 1); + if (count >= threshold) + count -= max; + bitCount += nbBits; + } + + count--; /* extra accuracy */ + remaining -= count < 0 ? -count : count; /* -1 means +1 */ + normalizedCounter[charnum++] = (short)count; + previous0 = !count; + while (remaining < threshold) { + nbBits--; + threshold >>= 1; + } + + if ((ip <= iend - 7) || (ip + (bitCount >> 3) <= iend - 4)) { + ip += bitCount >> 3; + bitCount &= 7; + } else { + bitCount -= (int)(8 * (iend - 4 - ip)); + ip = iend - 4; + } + bitStream = ZSTD_readLE32(ip) >> (bitCount & 31); + } + } /* while ((remaining>1) & (charnum<=*maxSVPtr)) */ + if (remaining != 1) + return ERROR(corruption_detected); + if (bitCount > 32) + return ERROR(corruption_detected); + *maxSVPtr = charnum - 1; + + ip += (bitCount + 7) >> 3; + return ip - istart; +} + +/*! HUF_readStats() : + Read compact Huffman tree, saved by HUF_writeCTable(). + `huffWeight` is destination buffer. + `rankStats` is assumed to be a table of at least HUF_TABLELOG_MAX U32. + @return : size read from `src` , or an error Code . + Note : Needed by HUF_readCTable() and HUF_readDTableX?() . +*/ +size_t HUF_readStats_wksp(BYTE *huffWeight, size_t hwSize, U32 *rankStats, U32 *nbSymbolsPtr, U32 *tableLogPtr, const void *src, size_t srcSize, void *workspace, size_t workspaceSize) +{ + U32 weightTotal; + const BYTE *ip = (const BYTE *)src; + size_t iSize; + size_t oSize; + + if (!srcSize) + return ERROR(srcSize_wrong); + iSize = ip[0]; + /* memset(huffWeight, 0, hwSize); */ /* is not necessary, even though some analyzer complain ... */ + + if (iSize >= 128) { /* special header */ + oSize = iSize - 127; + iSize = ((oSize + 1) / 2); + if (iSize + 1 > srcSize) + return ERROR(srcSize_wrong); + if (oSize >= hwSize) + return ERROR(corruption_detected); + ip += 1; + { + U32 n; + for (n = 0; n < oSize; n += 2) { + huffWeight[n] = ip[n / 2] >> 4; + huffWeight[n + 1] = ip[n / 2] & 15; + } + } + } else { /* header compressed with FSE (normal case) */ + if (iSize + 1 > srcSize) + return ERROR(srcSize_wrong); + oSize = FSE_decompress_wksp(huffWeight, hwSize - 1, ip + 1, iSize, 6, workspace, workspaceSize); /* max (hwSize-1) values decoded, as last one is implied */ + if (FSE_isError(oSize)) + return oSize; + } + + /* collect weight stats */ + memset(rankStats, 0, (HUF_TABLELOG_MAX + 1) * sizeof(U32)); + weightTotal = 0; + { + U32 n; + for (n = 0; n < oSize; n++) { + if (huffWeight[n] >= HUF_TABLELOG_MAX) + return ERROR(corruption_detected); + rankStats[huffWeight[n]]++; + weightTotal += (1 << huffWeight[n]) >> 1; + } + } + if (weightTotal == 0) + return ERROR(corruption_detected); + + /* get last non-null symbol weight (implied, total must be 2^n) */ + { + U32 const tableLog = BIT_highbit32(weightTotal) + 1; + if (tableLog > HUF_TABLELOG_MAX) + return ERROR(corruption_detected); + *tableLogPtr = tableLog; + /* determine last weight */ + { + U32 const total = 1 << tableLog; + U32 const rest = total - weightTotal; + U32 const verif = 1 << BIT_highbit32(rest); + U32 const lastWeight = BIT_highbit32(rest) + 1; + if (verif != rest) + return ERROR(corruption_detected); /* last value must be a clean power of 2 */ + huffWeight[oSize] = (BYTE)lastWeight; + rankStats[lastWeight]++; + } + } + + /* check tree construction validity */ + if ((rankStats[1] < 2) || (rankStats[1] & 1)) + return ERROR(corruption_detected); /* by construction : at least 2 elts of rank 1, must be even */ + + /* results */ + *nbSymbolsPtr = (U32)(oSize + 1); + return iSize + 1; +} |