lib/zstd/entropy_common.c

   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   ===*/
  49 unsigned FSE_versionNumber(void) { return FSE_VERSION_NUMBER; }
  50
  51 /*===   Error Management   ===*/
  52 unsigned FSE_isError(size_t code) { return ERR_isError(code); }
  53
  54 unsigned HUF_isError(size_t code) { return ERR_isError(code); }
  55
  56 /*-**************************************************************
  57 *  FSE NCount encoding-decoding
  58 ****************************************************************/
  59 size_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 */
 167 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)
 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 }