LXR linux/lib/zstd/entropy

   1/*
   2 * Common functions of New Generation Entropy library
   3 * Copyright (C) 2016, Yann Collet.
   4 *
   5 * BSD 2-Clause License (http://www.opensource.org/licenses/bsd-license.php)
   6 *
   7 * Redistribution and use in source and binary forms, with or without
   8 * modification, are permitted provided that the following conditions are
   9 * met:
  10 *
  11 *   * Redistributions of source code must retain the above copyright
  12 * notice, this list of conditions and the following disclaimer.
  13 *   * Redistributions in binary form must reproduce the above
  14 * copyright notice, this list of conditions and the following disclaimer
  15 * in the documentation and/or other materials provided with the
  16 * distribution.
  17 *
  18 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
  19 * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
  20 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
  21 * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
  22 * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
  23 * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
  24 * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
  25 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
  26 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
  27 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
  28 * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  29 *
  30 * This program is free software; you can redistribute it and/or modify it under
  31 * the terms of the GNU General Public License version 2 as published by the
  32 * Free Software Foundation. This program is dual-licensed; you may select
  33 * either version 2 of the GNU General Public License ("GPL") or BSD license
  34 * ("BSD").
  35 *
  36 * You can contact the author at :
  37 * - Source repository : https://github.com/Cyan4973/FiniteStateEntropy
  38 */
  39
  40/* *************************************
  41*  Dependencies
  42***************************************/
  43#include "error_private.h" /* ERR_*, ERROR */
  44#include "fse.h"
  45#include "huf.h"
  46#include "mem.h"
  47
  48/*===   Version   ===*/
  49unsigned FSE_versionNumber(void) { return FSE_VERSION_NUMBER; }
  50
  51/*===   Error Management   ===*/
  52unsigned FSE_isError(size_t code) { return ERR_isError(code); }
  53
  54unsigned HUF_isError(size_t code) { return ERR_isError(code); }
  55
  56/*-**************************************************************
  57*  FSE NCount encoding-decoding
  58****************************************************************/
  59size_t FSE_readNCount(short *normalizedCounter, unsigned *maxSVPtr, unsigned *tableLogPtr, const void *headerBuffer, size_t hbSize)
  60{
  61        const BYTE *const istart = (const BYTE *)headerBuffer;
  62        const BYTE *const iend = istart + hbSize;
  63        const BYTE *ip = istart;
  64        int nbBits;
  65        int remaining;
  66        int threshold;
  67        U32 bitStream;
  68        int bitCount;
  69        unsigned charnum = 0;
  70        int previous0 = 0;
  71
  72        if (hbSize < 4)
  73                return ERROR(srcSize_wrong);
  74        bitStream = ZSTD_readLE32(ip);
  75        nbBits = (bitStream & 0xF) + FSE_MIN_TABLELOG; /* extract tableLog */
  76        if (nbBits > FSE_TABLELOG_ABSOLUTE_MAX)
  77                return ERROR(tableLog_tooLarge);
  78        bitStream >>= 4;
  79        bitCount = 4;
  80        *tableLogPtr = nbBits;
  81        remaining = (1 << nbBits) + 1;
  82        threshold = 1 << nbBits;
  83        nbBits++;
  84
  85        while ((remaining > 1) & (charnum <= *maxSVPtr)) {
  86                if (previous0) {
  87                        unsigned n0 = charnum;
  88                        while ((bitStream & 0xFFFF) == 0xFFFF) {
  89                                n0 += 24;
  90                                if (ip < iend - 5) {
  91                                        ip += 2;
  92                                        bitStream = ZSTD_readLE32(ip) >> bitCount;
  93                                } else {
  94                                        bitStream >>= 16;
  95                                        bitCount += 16;
  96                                }
  97                        }
  98                        while ((bitStream & 3) == 3) {
  99                                n0 += 3;
 100                                bitStream >>= 2;
 101                                bitCount += 2;
 102                        }
 103                        n0 += bitStream & 3;
 104                        bitCount += 2;
 105                        if (n0 > *maxSVPtr)
 106                                return ERROR(maxSymbolValue_tooSmall);
 107                        while (charnum < n0)
 108                                normalizedCounter[charnum++] = 0;
 109                        if ((ip <= iend - 7) || (ip + (bitCount >> 3) <= iend - 4)) {
 110                                ip += bitCount >> 3;
 111                                bitCount &= 7;
 112                                bitStream = ZSTD_readLE32(ip) >> bitCount;
 113                        } else {
 114                                bitStream >>= 2;
 115                        }
 116                }
 117                {
 118                        int const max = (2 * threshold - 1) - remaining;
 119                        int count;
 120
 121                        if ((bitStream & (threshold - 1)) < (U32)max) {
 122                                count = bitStream & (threshold - 1);
 123                                bitCount += nbBits - 1;
 124                        } else {
 125                                count = bitStream & (2 * threshold - 1);
 126                                if (count >= threshold)
 127                                        count -= max;
 128                                bitCount += nbBits;
 129                        }
 130
 131                        count--;                                 /* extra accuracy */
 132                        remaining -= count < 0 ? -count : count; /* -1 means +1 */
 133                        normalizedCounter[charnum++] = (short)count;
 134                        previous0 = !count;
 135                        while (remaining < threshold) {
 136                                nbBits--;
 137                                threshold >>= 1;
 138                        }
 139
 140                        if ((ip <= iend - 7) || (ip + (bitCount >> 3) <= iend - 4)) {
 141                                ip += bitCount >> 3;
 142                                bitCount &= 7;
 143                        } else {
 144                                bitCount -= (int)(8 * (iend - 4 - ip));
 145                                ip = iend - 4;
 146                        }
 147                        bitStream = ZSTD_readLE32(ip) >> (bitCount & 31);
 148                }
 149        } /* while ((remaining>1) & (charnum<=*maxSVPtr)) */
 150        if (remaining != 1)
 151                return ERROR(corruption_detected);
 152        if (bitCount > 32)
 153                return ERROR(corruption_detected);
 154        *maxSVPtr = charnum - 1;
 155
 156        ip += (bitCount + 7) >> 3;
 157        return ip - istart;
 158}
 159
 160/*! HUF_readStats() :
 161        Read compact Huffman tree, saved by HUF_writeCTable().
 162        `huffWeight` is destination buffer.
 163        `rankStats` is assumed to be a table of at least HUF_TABLELOG_MAX U32.
 164        @return : size read from `src` , or an error Code .
 165        Note : Needed by HUF_readCTable() and HUF_readDTableX?() .
 166*/
 167size_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)
 168{
 169        U32 weightTotal;
 170        const BYTE *ip = (const BYTE *)src;
 171        size_t iSize;
 172        size_t oSize;
 173
 174        if (!srcSize)
 175                return ERROR(srcSize_wrong);
 176        iSize = ip[0];
 177        /* memset(huffWeight, 0, hwSize);   */ /* is not necessary, even though some analyzer complain ... */
 178
 179        if (iSize >= 128) { /* special header */
 180                oSize = iSize - 127;
 181                iSize = ((oSize + 1) / 2);
 182                if (iSize + 1 > srcSize)
 183                        return ERROR(srcSize_wrong);
 184                if (oSize >= hwSize)
 185                        return ERROR(corruption_detected);
 186                ip += 1;
 187                {
 188                        U32 n;
 189                        for (n = 0; n < oSize; n += 2) {
 190                                huffWeight[n] = ip[n / 2] >> 4;
 191                                huffWeight[n + 1] = ip[n / 2] & 15;
 192                        }
 193                }
 194        } else {                                                 /* header compressed with FSE (normal case) */
 195                if (iSize + 1 > srcSize)
 196                        return ERROR(srcSize_wrong);
 197                oSize = FSE_decompress_wksp(huffWeight, hwSize - 1, ip + 1, iSize, 6, workspace, workspaceSize); /* max (hwSize-1) values decoded, as last one is implied */
 198                if (FSE_isError(oSize))
 199                        return oSize;
 200        }
 201
 202        /* collect weight stats */
 203        memset(rankStats, 0, (HUF_TABLELOG_MAX + 1) * sizeof(U32));
 204        weightTotal = 0;
 205        {
 206                U32 n;
 207                for (n = 0; n < oSize; n++) {
 208                        if (huffWeight[n] >= HUF_TABLELOG_MAX)
 209                                return ERROR(corruption_detected);
 210                        rankStats[huffWeight[n]]++;
 211                        weightTotal += (1 << huffWeight[n]) >> 1;
 212                }
 213        }
 214        if (weightTotal == 0)
 215                return ERROR(corruption_detected);
 216
 217        /* get last non-null symbol weight (implied, total must be 2^n) */
 218        {
 219                U32 const tableLog = BIT_highbit32(weightTotal) + 1;
 220                if (tableLog > HUF_TABLELOG_MAX)
 221                        return ERROR(corruption_detected);
 222                *tableLogPtr = tableLog;
 223                /* determine last weight */
 224                {
 225                        U32 const total = 1 << tableLog;
 226                        U32 const rest = total - weightTotal;
 227                        U32 const verif = 1 << BIT_highbit32(rest);
 228                        U32 const lastWeight = BIT_highbit32(rest) + 1;
 229                        if (verif != rest)
 230                                return ERROR(corruption_detected); /* last value must be a clean power of 2 */
 231                        huffWeight[oSize] = (BYTE)lastWeight;
 232                        rankStats[lastWeight]++;
 233                }
 234        }
 235
 236        /* check tree construction validity */
 237        if ((rankStats[1] < 2) || (rankStats[1] & 1))
 238                return ERROR(corruption_detected); /* by construction : at least 2 elts of rank 1, must be even */
 239
 240        /* results */
 241        *nbSymbolsPtr = (U32)(oSize + 1);
 242        return iSize + 1;
 243}
 244