1 /* ****************************************************************** 2 * Common functions of New Generation Entropy library 3 * Copyright (c) 2016-2020, Yann Collet, Facebook, Inc. 4 * 5 * You can contact the author at : 6 * - FSE+HUF source repository : https://github.com/Cyan4973/FiniteStateEntropy 7 * - Public forum : https://groups.google.com/forum/#!forum/lz4c 8 * 9 * This source code is licensed under both the BSD-style license (found in the 10 * LICENSE file in the root directory of this source tree) and the GPLv2 (found 11 * in the COPYING file in the root directory of this source tree). 12 * You may select, at your option, one of the above-listed licenses. 13 ****************************************************************** */ 14 15 /* ************************************* 16 * Dependencies 17 ***************************************/ 18 #include "mem.h" 19 #include "error_private.h" /* ERR_*, ERROR */ 20 #define FSE_STATIC_LINKING_ONLY /* FSE_MIN_TABLELOG */ 21 #include "fse.h" 22 #define HUF_STATIC_LINKING_ONLY /* HUF_TABLELOG_ABSOLUTEMAX */ 23 #include "huf.h" 24 25 26 /*=== Version ===*/ 27 unsigned FSE_versionNumber(void) { return FSE_VERSION_NUMBER; } 28 29 30 /*=== Error Management ===*/ 31 unsigned FSE_isError(size_t code) { return ERR_isError(code); } 32 const char* FSE_getErrorName(size_t code) { return ERR_getErrorName(code); } 33 34 unsigned HUF_isError(size_t code) { return ERR_isError(code); } 35 const char* HUF_getErrorName(size_t code) { return ERR_getErrorName(code); } 36 37 38 /*-************************************************************** 39 * FSE NCount encoding-decoding 40 ****************************************************************/ 41 static U32 FSE_ctz(U32 val) 42 { 43 assert(val != 0); 44 { 45 # if defined(_MSC_VER) /* Visual */ 46 unsigned long r=0; 47 return _BitScanForward(&r, val) ? (unsigned)r : 0; 48 # elif defined(__GNUC__) && (__GNUC__ >= 3) /* GCC Intrinsic */ 49 return __builtin_ctz(val); 50 # elif defined(__ICCARM__) /* IAR Intrinsic */ 51 return __CTZ(val); 52 # else /* Software version */ 53 U32 count = 0; 54 while ((val & 1) == 0) { 55 val >>= 1; 56 ++count; 57 } 58 return count; 59 # endif 60 } 61 } 62 63 FORCE_INLINE_TEMPLATE 64 size_t FSE_readNCount_body(short* normalizedCounter, unsigned* maxSVPtr, unsigned* tableLogPtr, 65 const void* headerBuffer, size_t hbSize) 66 { 67 const BYTE* const istart = (const BYTE*) headerBuffer; 68 const BYTE* const iend = istart + hbSize; 69 const BYTE* ip = istart; 70 int nbBits; 71 int remaining; 72 int threshold; 73 U32 bitStream; 74 int bitCount; 75 unsigned charnum = 0; 76 unsigned const maxSV1 = *maxSVPtr + 1; 77 int previous0 = 0; 78 79 if (hbSize < 8) { 80 /* This function only works when hbSize >= 8 */ 81 char buffer[8] = {0}; 82 ZSTD_memcpy(buffer, headerBuffer, hbSize); 83 { size_t const countSize = FSE_readNCount(normalizedCounter, maxSVPtr, tableLogPtr, 84 buffer, sizeof(buffer)); 85 if (FSE_isError(countSize)) return countSize; 86 if (countSize > hbSize) return ERROR(corruption_detected); 87 return countSize; 88 } } 89 assert(hbSize >= 8); 90 91 /* init */ 92 ZSTD_memset(normalizedCounter, 0, (*maxSVPtr+1) * sizeof(normalizedCounter[0])); /* all symbols not present in NCount have a frequency of 0 */ 93 bitStream = MEM_readLE32(ip); 94 nbBits = (bitStream & 0xF) + FSE_MIN_TABLELOG; /* extract tableLog */ 95 if (nbBits > FSE_TABLELOG_ABSOLUTE_MAX) return ERROR(tableLog_tooLarge); 96 bitStream >>= 4; 97 bitCount = 4; 98 *tableLogPtr = nbBits; 99 remaining = (1<<nbBits)+1; 100 threshold = 1<<nbBits; 101 nbBits++; 102 103 for (;;) { 104 if (previous0) { 105 /* Count the number of repeats. Each time the 106 * 2-bit repeat code is 0b11 there is another 107 * repeat. 108 * Avoid UB by setting the high bit to 1. 109 */ 110 int repeats = FSE_ctz(~bitStream | 0x80000000) >> 1; 111 while (repeats >= 12) { 112 charnum += 3 * 12; 113 if (LIKELY(ip <= iend-7)) { 114 ip += 3; 115 } else { 116 bitCount -= (int)(8 * (iend - 7 - ip)); 117 bitCount &= 31; 118 ip = iend - 4; 119 } 120 bitStream = MEM_readLE32(ip) >> bitCount; 121 repeats = FSE_ctz(~bitStream | 0x80000000) >> 1; 122 } 123 charnum += 3 * repeats; 124 bitStream >>= 2 * repeats; 125 bitCount += 2 * repeats; 126 127 /* Add the final repeat which isn't 0b11. */ 128 assert((bitStream & 3) < 3); 129 charnum += bitStream & 3; 130 bitCount += 2; 131 132 /* This is an error, but break and return an error 133 * at the end, because returning out of a loop makes 134 * it harder for the compiler to optimize. 135 */ 136 if (charnum >= maxSV1) break; 137 138 /* We don't need to set the normalized count to 0 139 * because we already memset the whole buffer to 0. 140 */ 141 142 if (LIKELY(ip <= iend-7) || (ip + (bitCount>>3) <= iend-4)) { 143 assert((bitCount >> 3) <= 3); /* For first condition to work */ 144 ip += bitCount>>3; 145 bitCount &= 7; 146 } else { 147 bitCount -= (int)(8 * (iend - 4 - ip)); 148 bitCount &= 31; 149 ip = iend - 4; 150 } 151 bitStream = MEM_readLE32(ip) >> bitCount; 152 } 153 { 154 int const max = (2*threshold-1) - remaining; 155 int count; 156 157 if ((bitStream & (threshold-1)) < (U32)max) { 158 count = bitStream & (threshold-1); 159 bitCount += nbBits-1; 160 } else { 161 count = bitStream & (2*threshold-1); 162 if (count >= threshold) count -= max; 163 bitCount += nbBits; 164 } 165 166 count--; /* extra accuracy */ 167 /* When it matters (small blocks), this is a 168 * predictable branch, because we don't use -1. 169 */ 170 if (count >= 0) { 171 remaining -= count; 172 } else { 173 assert(count == -1); 174 remaining += count; 175 } 176 normalizedCounter[charnum++] = (short)count; 177 previous0 = !count; 178 179 assert(threshold > 1); 180 if (remaining < threshold) { 181 /* This branch can be folded into the 182 * threshold update condition because we 183 * know that threshold > 1. 184 */ 185 if (remaining <= 1) break; 186 nbBits = BIT_highbit32(remaining) + 1; 187 threshold = 1 << (nbBits - 1); 188 } 189 if (charnum >= maxSV1) break; 190 191 if (LIKELY(ip <= iend-7) || (ip + (bitCount>>3) <= iend-4)) { 192 ip += bitCount>>3; 193 bitCount &= 7; 194 } else { 195 bitCount -= (int)(8 * (iend - 4 - ip)); 196 bitCount &= 31; 197 ip = iend - 4; 198 } 199 bitStream = MEM_readLE32(ip) >> bitCount; 200 } } 201 if (remaining != 1) return ERROR(corruption_detected); 202 /* Only possible when there are too many zeros. */ 203 if (charnum > maxSV1) return ERROR(maxSymbolValue_tooSmall); 204 if (bitCount > 32) return ERROR(corruption_detected); 205 *maxSVPtr = charnum-1; 206 207 ip += (bitCount+7)>>3; 208 return ip-istart; 209 } 210 211 /* Avoids the FORCE_INLINE of the _body() function. */ 212 static size_t FSE_readNCount_body_default( 213 short* normalizedCounter, unsigned* maxSVPtr, unsigned* tableLogPtr, 214 const void* headerBuffer, size_t hbSize) 215 { 216 return FSE_readNCount_body(normalizedCounter, maxSVPtr, tableLogPtr, headerBuffer, hbSize); 217 } 218 219 #if DYNAMIC_BMI2 220 TARGET_ATTRIBUTE("bmi2") static size_t FSE_readNCount_body_bmi2( 221 short* normalizedCounter, unsigned* maxSVPtr, unsigned* tableLogPtr, 222 const void* headerBuffer, size_t hbSize) 223 { 224 return FSE_readNCount_body(normalizedCounter, maxSVPtr, tableLogPtr, headerBuffer, hbSize); 225 } 226 #endif 227 228 size_t FSE_readNCount_bmi2( 229 short* normalizedCounter, unsigned* maxSVPtr, unsigned* tableLogPtr, 230 const void* headerBuffer, size_t hbSize, int bmi2) 231 { 232 #if DYNAMIC_BMI2 233 if (bmi2) { 234 return FSE_readNCount_body_bmi2(normalizedCounter, maxSVPtr, tableLogPtr, headerBuffer, hbSize); 235 } 236 #endif 237 (void)bmi2; 238 return FSE_readNCount_body_default(normalizedCounter, maxSVPtr, tableLogPtr, headerBuffer, hbSize); 239 } 240 241 size_t FSE_readNCount( 242 short* normalizedCounter, unsigned* maxSVPtr, unsigned* tableLogPtr, 243 const void* headerBuffer, size_t hbSize) 244 { 245 return FSE_readNCount_bmi2(normalizedCounter, maxSVPtr, tableLogPtr, headerBuffer, hbSize, /* bmi2 */ 0); 246 } 247 248 249 /*! HUF_readStats() : 250 Read compact Huffman tree, saved by HUF_writeCTable(). 251 `huffWeight` is destination buffer. 252 `rankStats` is assumed to be a table of at least HUF_TABLELOG_MAX U32. 253 @return : size read from `src` , or an error Code . 254 Note : Needed by HUF_readCTable() and HUF_readDTableX?() . 255 */ 256 size_t HUF_readStats(BYTE* huffWeight, size_t hwSize, U32* rankStats, 257 U32* nbSymbolsPtr, U32* tableLogPtr, 258 const void* src, size_t srcSize) 259 { 260 U32 wksp[HUF_READ_STATS_WORKSPACE_SIZE_U32]; 261 return HUF_readStats_wksp(huffWeight, hwSize, rankStats, nbSymbolsPtr, tableLogPtr, src, srcSize, wksp, sizeof(wksp), /* bmi2 */ 0); 262 } 263 264 FORCE_INLINE_TEMPLATE size_t 265 HUF_readStats_body(BYTE* huffWeight, size_t hwSize, U32* rankStats, 266 U32* nbSymbolsPtr, U32* tableLogPtr, 267 const void* src, size_t srcSize, 268 void* workSpace, size_t wkspSize, 269 int bmi2) 270 { 271 U32 weightTotal; 272 const BYTE* ip = (const BYTE*) src; 273 size_t iSize; 274 size_t oSize; 275 276 if (!srcSize) return ERROR(srcSize_wrong); 277 iSize = ip[0]; 278 /* ZSTD_memset(huffWeight, 0, hwSize); *//* is not necessary, even though some analyzer complain ... */ 279 280 if (iSize >= 128) { /* special header */ 281 oSize = iSize - 127; 282 iSize = ((oSize+1)/2); 283 if (iSize+1 > srcSize) return ERROR(srcSize_wrong); 284 if (oSize >= hwSize) return ERROR(corruption_detected); 285 ip += 1; 286 { U32 n; 287 for (n=0; n<oSize; n+=2) { 288 huffWeight[n] = ip[n/2] >> 4; 289 huffWeight[n+1] = ip[n/2] & 15; 290 } } } 291 else { /* header compressed with FSE (normal case) */ 292 if (iSize+1 > srcSize) return ERROR(srcSize_wrong); 293 /* max (hwSize-1) values decoded, as last one is implied */ 294 oSize = FSE_decompress_wksp_bmi2(huffWeight, hwSize-1, ip+1, iSize, 6, workSpace, wkspSize, bmi2); 295 if (FSE_isError(oSize)) return oSize; 296 } 297 298 /* collect weight stats */ 299 ZSTD_memset(rankStats, 0, (HUF_TABLELOG_MAX + 1) * sizeof(U32)); 300 weightTotal = 0; 301 { U32 n; for (n=0; n<oSize; n++) { 302 if (huffWeight[n] >= HUF_TABLELOG_MAX) return ERROR(corruption_detected); 303 rankStats[huffWeight[n]]++; 304 weightTotal += (1 << huffWeight[n]) >> 1; 305 } } 306 if (weightTotal == 0) return ERROR(corruption_detected); 307 308 /* get last non-null symbol weight (implied, total must be 2^n) */ 309 { U32 const tableLog = BIT_highbit32(weightTotal) + 1; 310 if (tableLog > HUF_TABLELOG_MAX) return ERROR(corruption_detected); 311 *tableLogPtr = tableLog; 312 /* determine last weight */ 313 { U32 const total = 1 << tableLog; 314 U32 const rest = total - weightTotal; 315 U32 const verif = 1 << BIT_highbit32(rest); 316 U32 const lastWeight = BIT_highbit32(rest) + 1; 317 if (verif != rest) return ERROR(corruption_detected); /* last value must be a clean power of 2 */ 318 huffWeight[oSize] = (BYTE)lastWeight; 319 rankStats[lastWeight]++; 320 } } 321 322 /* check tree construction validity */ 323 if ((rankStats[1] < 2) || (rankStats[1] & 1)) return ERROR(corruption_detected); /* by construction : at least 2 elts of rank 1, must be even */ 324 325 /* results */ 326 *nbSymbolsPtr = (U32)(oSize+1); 327 return iSize+1; 328 } 329 330 /* Avoids the FORCE_INLINE of the _body() function. */ 331 static size_t HUF_readStats_body_default(BYTE* huffWeight, size_t hwSize, U32* rankStats, 332 U32* nbSymbolsPtr, U32* tableLogPtr, 333 const void* src, size_t srcSize, 334 void* workSpace, size_t wkspSize) 335 { 336 return HUF_readStats_body(huffWeight, hwSize, rankStats, nbSymbolsPtr, tableLogPtr, src, srcSize, workSpace, wkspSize, 0); 337 } 338 339 #if DYNAMIC_BMI2 340 static TARGET_ATTRIBUTE("bmi2") size_t HUF_readStats_body_bmi2(BYTE* huffWeight, size_t hwSize, U32* rankStats, 341 U32* nbSymbolsPtr, U32* tableLogPtr, 342 const void* src, size_t srcSize, 343 void* workSpace, size_t wkspSize) 344 { 345 return HUF_readStats_body(huffWeight, hwSize, rankStats, nbSymbolsPtr, tableLogPtr, src, srcSize, workSpace, wkspSize, 1); 346 } 347 #endif 348 349 size_t HUF_readStats_wksp(BYTE* huffWeight, size_t hwSize, U32* rankStats, 350 U32* nbSymbolsPtr, U32* tableLogPtr, 351 const void* src, size_t srcSize, 352 void* workSpace, size_t wkspSize, 353 int bmi2) 354 { 355 #if DYNAMIC_BMI2 356 if (bmi2) { 357 return HUF_readStats_body_bmi2(huffWeight, hwSize, rankStats, nbSymbolsPtr, tableLogPtr, src, srcSize, workSpace, wkspSize); 358 } 359 #endif 360 (void)bmi2; 361 return HUF_readStats_body_default(huffWeight, hwSize, rankStats, nbSymbolsPtr, tableLogPtr, src, srcSize, workSpace, wkspSize); 362 } 363