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