1 /* ****************************************************************** 2 * Common functions of New Generation Entropy library 3 * Copyright (c) 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 if (val != 0) { 47 unsigned long r; 48 _BitScanForward(&r, val); 49 return (unsigned)r; 50 } else { 51 /* Should not reach this code path */ 52 __assume(0); 53 } 54 # elif defined(__GNUC__) && (__GNUC__ >= 3) /* GCC Intrinsic */ 55 return __builtin_ctz(val); 56 # elif defined(__ICCARM__) /* IAR Intrinsic */ 57 return __CTZ(val); 58 # else /* Software version */ 59 U32 count = 0; 60 while ((val & 1) == 0) { 61 val >>= 1; 62 ++count; 63 } 64 return count; 65 # endif 66 } 67 } 68 69 FORCE_INLINE_TEMPLATE 70 size_t FSE_readNCount_body(short* normalizedCounter, unsigned* maxSVPtr, unsigned* tableLogPtr, 71 const void* headerBuffer, size_t hbSize) 72 { 73 const BYTE* const istart = (const BYTE*) headerBuffer; 74 const BYTE* const iend = istart + hbSize; 75 const BYTE* ip = istart; 76 int nbBits; 77 int remaining; 78 int threshold; 79 U32 bitStream; 80 int bitCount; 81 unsigned charnum = 0; 82 unsigned const maxSV1 = *maxSVPtr + 1; 83 int previous0 = 0; 84 85 if (hbSize < 8) { 86 /* This function only works when hbSize >= 8 */ 87 char buffer[8] = {0}; 88 ZSTD_memcpy(buffer, headerBuffer, hbSize); 89 { size_t const countSize = FSE_readNCount(normalizedCounter, maxSVPtr, tableLogPtr, 90 buffer, sizeof(buffer)); 91 if (FSE_isError(countSize)) return countSize; 92 if (countSize > hbSize) return ERROR(corruption_detected); 93 return countSize; 94 } } 95 assert(hbSize >= 8); 96 97 /* init */ 98 ZSTD_memset(normalizedCounter, 0, (*maxSVPtr+1) * sizeof(normalizedCounter[0])); /* all symbols not present in NCount have a frequency of 0 */ 99 bitStream = MEM_readLE32(ip); 100 nbBits = (bitStream & 0xF) + FSE_MIN_TABLELOG; /* extract tableLog */ 101 if (nbBits > FSE_TABLELOG_ABSOLUTE_MAX) return ERROR(tableLog_tooLarge); 102 bitStream >>= 4; 103 bitCount = 4; 104 *tableLogPtr = nbBits; 105 remaining = (1<<nbBits)+1; 106 threshold = 1<<nbBits; 107 nbBits++; 108 109 for (;;) { 110 if (previous0) { 111 /* Count the number of repeats. Each time the 112 * 2-bit repeat code is 0b11 there is another 113 * repeat. 114 * Avoid UB by setting the high bit to 1. 115 */ 116 int repeats = FSE_ctz(~bitStream | 0x80000000) >> 1; 117 while (repeats >= 12) { 118 charnum += 3 * 12; 119 if (LIKELY(ip <= iend-7)) { 120 ip += 3; 121 } else { 122 bitCount -= (int)(8 * (iend - 7 - ip)); 123 bitCount &= 31; 124 ip = iend - 4; 125 } 126 bitStream = MEM_readLE32(ip) >> bitCount; 127 repeats = FSE_ctz(~bitStream | 0x80000000) >> 1; 128 } 129 charnum += 3 * repeats; 130 bitStream >>= 2 * repeats; 131 bitCount += 2 * repeats; 132 133 /* Add the final repeat which isn't 0b11. */ 134 assert((bitStream & 3) < 3); 135 charnum += bitStream & 3; 136 bitCount += 2; 137 138 /* This is an error, but break and return an error 139 * at the end, because returning out of a loop makes 140 * it harder for the compiler to optimize. 141 */ 142 if (charnum >= maxSV1) break; 143 144 /* We don't need to set the normalized count to 0 145 * because we already memset the whole buffer to 0. 146 */ 147 148 if (LIKELY(ip <= iend-7) || (ip + (bitCount>>3) <= iend-4)) { 149 assert((bitCount >> 3) <= 3); /* For first condition to work */ 150 ip += bitCount>>3; 151 bitCount &= 7; 152 } else { 153 bitCount -= (int)(8 * (iend - 4 - ip)); 154 bitCount &= 31; 155 ip = iend - 4; 156 } 157 bitStream = MEM_readLE32(ip) >> bitCount; 158 } 159 { 160 int const max = (2*threshold-1) - remaining; 161 int count; 162 163 if ((bitStream & (threshold-1)) < (U32)max) { 164 count = bitStream & (threshold-1); 165 bitCount += nbBits-1; 166 } else { 167 count = bitStream & (2*threshold-1); 168 if (count >= threshold) count -= max; 169 bitCount += nbBits; 170 } 171 172 count--; /* extra accuracy */ 173 /* When it matters (small blocks), this is a 174 * predictable branch, because we don't use -1. 175 */ 176 if (count >= 0) { 177 remaining -= count; 178 } else { 179 assert(count == -1); 180 remaining += count; 181 } 182 normalizedCounter[charnum++] = (short)count; 183 previous0 = !count; 184 185 assert(threshold > 1); 186 if (remaining < threshold) { 187 /* This branch can be folded into the 188 * threshold update condition because we 189 * know that threshold > 1. 190 */ 191 if (remaining <= 1) break; 192 nbBits = BIT_highbit32(remaining) + 1; 193 threshold = 1 << (nbBits - 1); 194 } 195 if (charnum >= maxSV1) break; 196 197 if (LIKELY(ip <= iend-7) || (ip + (bitCount>>3) <= iend-4)) { 198 ip += bitCount>>3; 199 bitCount &= 7; 200 } else { 201 bitCount -= (int)(8 * (iend - 4 - ip)); 202 bitCount &= 31; 203 ip = iend - 4; 204 } 205 bitStream = MEM_readLE32(ip) >> bitCount; 206 } } 207 if (remaining != 1) return ERROR(corruption_detected); 208 /* Only possible when there are too many zeros. */ 209 if (charnum > maxSV1) return ERROR(maxSymbolValue_tooSmall); 210 if (bitCount > 32) return ERROR(corruption_detected); 211 *maxSVPtr = charnum-1; 212 213 ip += (bitCount+7)>>3; 214 return ip-istart; 215 } 216 217 /* Avoids the FORCE_INLINE of the _body() function. */ 218 static size_t FSE_readNCount_body_default( 219 short* normalizedCounter, unsigned* maxSVPtr, unsigned* tableLogPtr, 220 const void* headerBuffer, size_t hbSize) 221 { 222 return FSE_readNCount_body(normalizedCounter, maxSVPtr, tableLogPtr, headerBuffer, hbSize); 223 } 224 225 #if DYNAMIC_BMI2 226 BMI2_TARGET_ATTRIBUTE static size_t FSE_readNCount_body_bmi2( 227 short* normalizedCounter, unsigned* maxSVPtr, unsigned* tableLogPtr, 228 const void* headerBuffer, size_t hbSize) 229 { 230 return FSE_readNCount_body(normalizedCounter, maxSVPtr, tableLogPtr, headerBuffer, hbSize); 231 } 232 #endif 233 234 size_t FSE_readNCount_bmi2( 235 short* normalizedCounter, unsigned* maxSVPtr, unsigned* tableLogPtr, 236 const void* headerBuffer, size_t hbSize, int bmi2) 237 { 238 #if DYNAMIC_BMI2 239 if (bmi2) { 240 return FSE_readNCount_body_bmi2(normalizedCounter, maxSVPtr, tableLogPtr, headerBuffer, hbSize); 241 } 242 #endif 243 (void)bmi2; 244 return FSE_readNCount_body_default(normalizedCounter, maxSVPtr, tableLogPtr, headerBuffer, hbSize); 245 } 246 247 size_t FSE_readNCount( 248 short* normalizedCounter, unsigned* maxSVPtr, unsigned* tableLogPtr, 249 const void* headerBuffer, size_t hbSize) 250 { 251 return FSE_readNCount_bmi2(normalizedCounter, maxSVPtr, tableLogPtr, headerBuffer, hbSize, /* bmi2 */ 0); 252 } 253 254 255 /*! HUF_readStats() : 256 Read compact Huffman tree, saved by HUF_writeCTable(). 257 `huffWeight` is destination buffer. 258 `rankStats` is assumed to be a table of at least HUF_TABLELOG_MAX U32. 259 @return : size read from `src` , or an error Code . 260 Note : Needed by HUF_readCTable() and HUF_readDTableX?() . 261 */ 262 size_t HUF_readStats(BYTE* huffWeight, size_t hwSize, U32* rankStats, 263 U32* nbSymbolsPtr, U32* tableLogPtr, 264 const void* src, size_t srcSize) 265 { 266 U32 wksp[HUF_READ_STATS_WORKSPACE_SIZE_U32]; 267 return HUF_readStats_wksp(huffWeight, hwSize, rankStats, nbSymbolsPtr, tableLogPtr, src, srcSize, wksp, sizeof(wksp), /* bmi2 */ 0); 268 } 269 270 FORCE_INLINE_TEMPLATE size_t 271 HUF_readStats_body(BYTE* huffWeight, size_t hwSize, U32* rankStats, 272 U32* nbSymbolsPtr, U32* tableLogPtr, 273 const void* src, size_t srcSize, 274 void* workSpace, size_t wkspSize, 275 int bmi2) 276 { 277 U32 weightTotal; 278 const BYTE* ip = (const BYTE*) src; 279 size_t iSize; 280 size_t oSize; 281 282 if (!srcSize) return ERROR(srcSize_wrong); 283 iSize = ip[0]; 284 /* ZSTD_memset(huffWeight, 0, hwSize); *//* is not necessary, even though some analyzer complain ... */ 285 286 if (iSize >= 128) { /* special header */ 287 oSize = iSize - 127; 288 iSize = ((oSize+1)/2); 289 if (iSize+1 > srcSize) return ERROR(srcSize_wrong); 290 if (oSize >= hwSize) return ERROR(corruption_detected); 291 ip += 1; 292 { U32 n; 293 for (n=0; n<oSize; n+=2) { 294 huffWeight[n] = ip[n/2] >> 4; 295 huffWeight[n+1] = ip[n/2] & 15; 296 } } } 297 else { /* header compressed with FSE (normal case) */ 298 if (iSize+1 > srcSize) return ERROR(srcSize_wrong); 299 /* max (hwSize-1) values decoded, as last one is implied */ 300 oSize = FSE_decompress_wksp_bmi2(huffWeight, hwSize-1, ip+1, iSize, 6, workSpace, wkspSize, bmi2); 301 if (FSE_isError(oSize)) return oSize; 302 } 303 304 /* collect weight stats */ 305 ZSTD_memset(rankStats, 0, (HUF_TABLELOG_MAX + 1) * sizeof(U32)); 306 weightTotal = 0; 307 { U32 n; for (n=0; n<oSize; n++) { 308 if (huffWeight[n] > HUF_TABLELOG_MAX) return ERROR(corruption_detected); 309 rankStats[huffWeight[n]]++; 310 weightTotal += (1 << huffWeight[n]) >> 1; 311 } } 312 if (weightTotal == 0) return ERROR(corruption_detected); 313 314 /* get last non-null symbol weight (implied, total must be 2^n) */ 315 { U32 const tableLog = BIT_highbit32(weightTotal) + 1; 316 if (tableLog > HUF_TABLELOG_MAX) return ERROR(corruption_detected); 317 *tableLogPtr = tableLog; 318 /* determine last weight */ 319 { U32 const total = 1 << tableLog; 320 U32 const rest = total - weightTotal; 321 U32 const verif = 1 << BIT_highbit32(rest); 322 U32 const lastWeight = BIT_highbit32(rest) + 1; 323 if (verif != rest) return ERROR(corruption_detected); /* last value must be a clean power of 2 */ 324 huffWeight[oSize] = (BYTE)lastWeight; 325 rankStats[lastWeight]++; 326 } } 327 328 /* check tree construction validity */ 329 if ((rankStats[1] < 2) || (rankStats[1] & 1)) return ERROR(corruption_detected); /* by construction : at least 2 elts of rank 1, must be even */ 330 331 /* results */ 332 *nbSymbolsPtr = (U32)(oSize+1); 333 return iSize+1; 334 } 335 336 /* Avoids the FORCE_INLINE of the _body() function. */ 337 static size_t HUF_readStats_body_default(BYTE* huffWeight, size_t hwSize, U32* rankStats, 338 U32* nbSymbolsPtr, U32* tableLogPtr, 339 const void* src, size_t srcSize, 340 void* workSpace, size_t wkspSize) 341 { 342 return HUF_readStats_body(huffWeight, hwSize, rankStats, nbSymbolsPtr, tableLogPtr, src, srcSize, workSpace, wkspSize, 0); 343 } 344 345 #if DYNAMIC_BMI2 346 static BMI2_TARGET_ATTRIBUTE size_t HUF_readStats_body_bmi2(BYTE* huffWeight, size_t hwSize, U32* rankStats, 347 U32* nbSymbolsPtr, U32* tableLogPtr, 348 const void* src, size_t srcSize, 349 void* workSpace, size_t wkspSize) 350 { 351 return HUF_readStats_body(huffWeight, hwSize, rankStats, nbSymbolsPtr, tableLogPtr, src, srcSize, workSpace, wkspSize, 1); 352 } 353 #endif 354 355 size_t HUF_readStats_wksp(BYTE* huffWeight, size_t hwSize, U32* rankStats, 356 U32* nbSymbolsPtr, U32* tableLogPtr, 357 const void* src, size_t srcSize, 358 void* workSpace, size_t wkspSize, 359 int bmi2) 360 { 361 #if DYNAMIC_BMI2 362 if (bmi2) { 363 return HUF_readStats_body_bmi2(huffWeight, hwSize, rankStats, nbSymbolsPtr, tableLogPtr, src, srcSize, workSpace, wkspSize); 364 } 365 #endif 366 (void)bmi2; 367 return HUF_readStats_body_default(huffWeight, hwSize, rankStats, nbSymbolsPtr, tableLogPtr, src, srcSize, workSpace, wkspSize); 368 } 369