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 You can contact the author at : 31 - FSE+HUF source repository : https://github.com/Cyan4973/FiniteStateEntropy 32 - Public forum : https://groups.google.com/forum/#!forum/lz4c 33 *************************************************************************** */ 34 35 /* ************************************* 36 * Dependencies 37 ***************************************/ 38 #include "mem.h" 39 #include "error_private.h" /* ERR_*, ERROR */ 40 #define FSE_STATIC_LINKING_ONLY /* FSE_MIN_TABLELOG */ 41 #include "fse.h" 42 #define HUF_STATIC_LINKING_ONLY /* HUF_TABLELOG_ABSOLUTEMAX */ 43 #include "huf.h" 44 45 46 /*=== Version ===*/ 47 unsigned FSE_versionNumber(void) { return FSE_VERSION_NUMBER; } 48 49 50 /*=== Error Management ===*/ 51 unsigned FSE_isError(size_t code) { return ERR_isError(code); } 52 const char* FSE_getErrorName(size_t code) { return ERR_getErrorName(code); } 53 54 unsigned HUF_isError(size_t code) { return ERR_isError(code); } 55 const char* HUF_getErrorName(size_t code) { return ERR_getErrorName(code); } 56 57 58 /*-************************************************************** 59 * FSE NCount encoding-decoding 60 ****************************************************************/ 61 size_t FSE_readNCount (short* normalizedCounter, unsigned* maxSVPtr, unsigned* tableLogPtr, 62 const void* headerBuffer, size_t hbSize) 63 { 64 const BYTE* const istart = (const BYTE*) headerBuffer; 65 const BYTE* const iend = istart + hbSize; 66 const BYTE* ip = istart; 67 int nbBits; 68 int remaining; 69 int threshold; 70 U32 bitStream; 71 int bitCount; 72 unsigned charnum = 0; 73 int previous0 = 0; 74 75 if (hbSize < 4) { 76 /* This function only works when hbSize >= 4 */ 77 char buffer[4]; 78 memset(buffer, 0, sizeof(buffer)); 79 memcpy(buffer, headerBuffer, hbSize); 80 { size_t const countSize = FSE_readNCount(normalizedCounter, maxSVPtr, tableLogPtr, 81 buffer, sizeof(buffer)); 82 if (FSE_isError(countSize)) return countSize; 83 if (countSize > hbSize) return ERROR(corruption_detected); 84 return countSize; 85 } } 86 assert(hbSize >= 4); 87 88 /* init */ 89 memset(normalizedCounter, 0, (*maxSVPtr+1) * sizeof(normalizedCounter[0])); /* all symbols not present in NCount have a frequency of 0 */ 90 bitStream = MEM_readLE32(ip); 91 nbBits = (bitStream & 0xF) + FSE_MIN_TABLELOG; /* extract tableLog */ 92 if (nbBits > FSE_TABLELOG_ABSOLUTE_MAX) return ERROR(tableLog_tooLarge); 93 bitStream >>= 4; 94 bitCount = 4; 95 *tableLogPtr = nbBits; 96 remaining = (1<<nbBits)+1; 97 threshold = 1<<nbBits; 98 nbBits++; 99 100 while ((remaining>1) & (charnum<=*maxSVPtr)) { 101 if (previous0) { 102 unsigned n0 = charnum; 103 while ((bitStream & 0xFFFF) == 0xFFFF) { 104 n0 += 24; 105 if (ip < iend-5) { 106 ip += 2; 107 bitStream = MEM_readLE32(ip) >> bitCount; 108 } else { 109 bitStream >>= 16; 110 bitCount += 16; 111 } } 112 while ((bitStream & 3) == 3) { 113 n0 += 3; 114 bitStream >>= 2; 115 bitCount += 2; 116 } 117 n0 += bitStream & 3; 118 bitCount += 2; 119 if (n0 > *maxSVPtr) return ERROR(maxSymbolValue_tooSmall); 120 while (charnum < n0) normalizedCounter[charnum++] = 0; 121 if ((ip <= iend-7) || (ip + (bitCount>>3) <= iend-4)) { 122 assert((bitCount >> 3) <= 3); /* For first condition to work */ 123 ip += bitCount>>3; 124 bitCount &= 7; 125 bitStream = MEM_readLE32(ip) >> bitCount; 126 } else { 127 bitStream >>= 2; 128 } } 129 { int const max = (2*threshold-1) - remaining; 130 int count; 131 132 if ((bitStream & (threshold-1)) < (U32)max) { 133 count = bitStream & (threshold-1); 134 bitCount += nbBits-1; 135 } else { 136 count = bitStream & (2*threshold-1); 137 if (count >= threshold) count -= max; 138 bitCount += nbBits; 139 } 140 141 count--; /* extra accuracy */ 142 remaining -= count < 0 ? -count : count; /* -1 means +1 */ 143 normalizedCounter[charnum++] = (short)count; 144 previous0 = !count; 145 while (remaining < threshold) { 146 nbBits--; 147 threshold >>= 1; 148 } 149 150 if ((ip <= iend-7) || (ip + (bitCount>>3) <= iend-4)) { 151 ip += bitCount>>3; 152 bitCount &= 7; 153 } else { 154 bitCount -= (int)(8 * (iend - 4 - ip)); 155 ip = iend - 4; 156 } 157 bitStream = MEM_readLE32(ip) >> (bitCount & 31); 158 } } /* while ((remaining>1) & (charnum<=*maxSVPtr)) */ 159 if (remaining != 1) return ERROR(corruption_detected); 160 if (bitCount > 32) return ERROR(corruption_detected); 161 *maxSVPtr = charnum-1; 162 163 ip += (bitCount+7)>>3; 164 return ip-istart; 165 } 166 167 168 /*! HUF_readStats() : 169 Read compact Huffman tree, saved by HUF_writeCTable(). 170 `huffWeight` is destination buffer. 171 `rankStats` is assumed to be a table of at least HUF_TABLELOG_MAX U32. 172 @return : size read from `src` , or an error Code . 173 Note : Needed by HUF_readCTable() and HUF_readDTableX?() . 174 */ 175 size_t HUF_readStats(BYTE* huffWeight, size_t hwSize, U32* rankStats, 176 U32* nbSymbolsPtr, U32* tableLogPtr, 177 const void* src, size_t srcSize) 178 { 179 U32 weightTotal; 180 const BYTE* ip = (const BYTE*) src; 181 size_t iSize; 182 size_t oSize; 183 184 if (!srcSize) return ERROR(srcSize_wrong); 185 iSize = ip[0]; 186 /* memset(huffWeight, 0, hwSize); *//* is not necessary, even though some analyzer complain ... */ 187 188 if (iSize >= 128) { /* special header */ 189 oSize = iSize - 127; 190 iSize = ((oSize+1)/2); 191 if (iSize+1 > srcSize) return ERROR(srcSize_wrong); 192 if (oSize >= hwSize) return ERROR(corruption_detected); 193 ip += 1; 194 { U32 n; 195 for (n=0; n<oSize; n+=2) { 196 huffWeight[n] = ip[n/2] >> 4; 197 huffWeight[n+1] = ip[n/2] & 15; 198 } } } 199 else { /* header compressed with FSE (normal case) */ 200 FSE_DTable fseWorkspace[FSE_DTABLE_SIZE_U32(6)]; /* 6 is max possible tableLog for HUF header (maybe even 5, to be tested) */ 201 if (iSize+1 > srcSize) return ERROR(srcSize_wrong); 202 oSize = FSE_decompress_wksp(huffWeight, hwSize-1, ip+1, iSize, fseWorkspace, 6); /* max (hwSize-1) values decoded, as last one is implied */ 203 if (FSE_isError(oSize)) return oSize; 204 } 205 206 /* collect weight stats */ 207 memset(rankStats, 0, (HUF_TABLELOG_MAX + 1) * sizeof(U32)); 208 weightTotal = 0; 209 { U32 n; for (n=0; n<oSize; n++) { 210 if (huffWeight[n] >= HUF_TABLELOG_MAX) return ERROR(corruption_detected); 211 rankStats[huffWeight[n]]++; 212 weightTotal += (1 << huffWeight[n]) >> 1; 213 } } 214 if (weightTotal == 0) return ERROR(corruption_detected); 215 216 /* get last non-null symbol weight (implied, total must be 2^n) */ 217 { U32 const tableLog = BIT_highbit32(weightTotal) + 1; 218 if (tableLog > HUF_TABLELOG_MAX) return ERROR(corruption_detected); 219 *tableLogPtr = tableLog; 220 /* determine last weight */ 221 { U32 const total = 1 << tableLog; 222 U32 const rest = total - weightTotal; 223 U32 const verif = 1 << BIT_highbit32(rest); 224 U32 const lastWeight = BIT_highbit32(rest) + 1; 225 if (verif != rest) return ERROR(corruption_detected); /* last value must be a clean power of 2 */ 226 huffWeight[oSize] = (BYTE)lastWeight; 227 rankStats[lastWeight]++; 228 } } 229 230 /* check tree construction validity */ 231 if ((rankStats[1] < 2) || (rankStats[1] & 1)) return ERROR(corruption_detected); /* by construction : at least 2 elts of rank 1, must be even */ 232 233 /* results */ 234 *nbSymbolsPtr = (U32)(oSize+1); 235 return iSize+1; 236 } 237