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1/* ******************************************************************2 * Common functions of New Generation Entropy library3 * Copyright (c) Yann Collet, Facebook, Inc.4 *5 * You can contact the author at :6 * - FSE+HUF source repository : https://github.com/Cyan4973/FiniteStateEntropy7 * - Public forum : https://groups.google.com/forum/#!forum/lz4c8 *9 * This source code is licensed under both the BSD-style license (found in the10 * LICENSE file in the root directory of this source tree) and the GPLv2 (found11 * 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* Dependencies17***************************************/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 ===*/27unsigned FSE_versionNumber(void) { return FSE_VERSION_NUMBER; }28 29 30/*=== Error Management ===*/31unsigned FSE_isError(size_t code) { return ERR_isError(code); }32const char* FSE_getErrorName(size_t code) { return ERR_getErrorName(code); }33 34unsigned HUF_isError(size_t code) { return ERR_isError(code); }35const char* HUF_getErrorName(size_t code) { return ERR_getErrorName(code); }36 37 38/*-**************************************************************39* FSE NCount encoding-decoding40****************************************************************/41static U32 FSE_ctz(U32 val)42{43 assert(val != 0);44 {45# if (__GNUC__ >= 3) /* GCC Intrinsic */46 return __builtin_ctz(val);47# else /* Software version */48 U32 count = 0;49 while ((val & 1) == 0) {50 val >>= 1;51 ++count;52 }53 return count;54# endif55 }56}57 58FORCE_INLINE_TEMPLATE59size_t FSE_readNCount_body(short* normalizedCounter, unsigned* maxSVPtr, unsigned* tableLogPtr,60 const void* headerBuffer, size_t hbSize)61{62 const BYTE* const istart = (const BYTE*) headerBuffer;63 const BYTE* const iend = istart + hbSize;64 const BYTE* ip = istart;65 int nbBits;66 int remaining;67 int threshold;68 U32 bitStream;69 int bitCount;70 unsigned charnum = 0;71 unsigned const maxSV1 = *maxSVPtr + 1;72 int previous0 = 0;73 74 if (hbSize < 8) {75 /* This function only works when hbSize >= 8 */76 char buffer[8] = {0};77 ZSTD_memcpy(buffer, headerBuffer, hbSize);78 { size_t const countSize = FSE_readNCount(normalizedCounter, maxSVPtr, tableLogPtr,79 buffer, sizeof(buffer));80 if (FSE_isError(countSize)) return countSize;81 if (countSize > hbSize) return ERROR(corruption_detected);82 return countSize;83 } }84 assert(hbSize >= 8);85 86 /* init */87 ZSTD_memset(normalizedCounter, 0, (*maxSVPtr+1) * sizeof(normalizedCounter[0])); /* all symbols not present in NCount have a frequency of 0 */88 bitStream = MEM_readLE32(ip);89 nbBits = (bitStream & 0xF) + FSE_MIN_TABLELOG; /* extract tableLog */90 if (nbBits > FSE_TABLELOG_ABSOLUTE_MAX) return ERROR(tableLog_tooLarge);91 bitStream >>= 4;92 bitCount = 4;93 *tableLogPtr = nbBits;94 remaining = (1<<nbBits)+1;95 threshold = 1<<nbBits;96 nbBits++;97 98 for (;;) {99 if (previous0) {100 /* Count the number of repeats. Each time the101 * 2-bit repeat code is 0b11 there is another102 * repeat.103 * Avoid UB by setting the high bit to 1.104 */105 int repeats = FSE_ctz(~bitStream | 0x80000000) >> 1;106 while (repeats >= 12) {107 charnum += 3 * 12;108 if (LIKELY(ip <= iend-7)) {109 ip += 3;110 } else {111 bitCount -= (int)(8 * (iend - 7 - ip));112 bitCount &= 31;113 ip = iend - 4;114 }115 bitStream = MEM_readLE32(ip) >> bitCount;116 repeats = FSE_ctz(~bitStream | 0x80000000) >> 1;117 }118 charnum += 3 * repeats;119 bitStream >>= 2 * repeats;120 bitCount += 2 * repeats;121 122 /* Add the final repeat which isn't 0b11. */123 assert((bitStream & 3) < 3);124 charnum += bitStream & 3;125 bitCount += 2;126 127 /* This is an error, but break and return an error128 * at the end, because returning out of a loop makes129 * it harder for the compiler to optimize.130 */131 if (charnum >= maxSV1) break;132 133 /* We don't need to set the normalized count to 0134 * because we already memset the whole buffer to 0.135 */136 137 if (LIKELY(ip <= iend-7) || (ip + (bitCount>>3) <= iend-4)) {138 assert((bitCount >> 3) <= 3); /* For first condition to work */139 ip += bitCount>>3;140 bitCount &= 7;141 } else {142 bitCount -= (int)(8 * (iend - 4 - ip));143 bitCount &= 31;144 ip = iend - 4;145 }146 bitStream = MEM_readLE32(ip) >> bitCount;147 }148 {149 int const max = (2*threshold-1) - remaining;150 int count;151 152 if ((bitStream & (threshold-1)) < (U32)max) {153 count = bitStream & (threshold-1);154 bitCount += nbBits-1;155 } else {156 count = bitStream & (2*threshold-1);157 if (count >= threshold) count -= max;158 bitCount += nbBits;159 }160 161 count--; /* extra accuracy */162 /* When it matters (small blocks), this is a163 * predictable branch, because we don't use -1.164 */165 if (count >= 0) {166 remaining -= count;167 } else {168 assert(count == -1);169 remaining += count;170 }171 normalizedCounter[charnum++] = (short)count;172 previous0 = !count;173 174 assert(threshold > 1);175 if (remaining < threshold) {176 /* This branch can be folded into the177 * threshold update condition because we178 * know that threshold > 1.179 */180 if (remaining <= 1) break;181 nbBits = BIT_highbit32(remaining) + 1;182 threshold = 1 << (nbBits - 1);183 }184 if (charnum >= maxSV1) break;185 186 if (LIKELY(ip <= iend-7) || (ip + (bitCount>>3) <= iend-4)) {187 ip += bitCount>>3;188 bitCount &= 7;189 } else {190 bitCount -= (int)(8 * (iend - 4 - ip));191 bitCount &= 31;192 ip = iend - 4;193 }194 bitStream = MEM_readLE32(ip) >> bitCount;195 } }196 if (remaining != 1) return ERROR(corruption_detected);197 /* Only possible when there are too many zeros. */198 if (charnum > maxSV1) return ERROR(maxSymbolValue_tooSmall);199 if (bitCount > 32) return ERROR(corruption_detected);200 *maxSVPtr = charnum-1;201 202 ip += (bitCount+7)>>3;203 return ip-istart;204}205 206/* Avoids the FORCE_INLINE of the _body() function. */207static size_t FSE_readNCount_body_default(208 short* normalizedCounter, unsigned* maxSVPtr, unsigned* tableLogPtr,209 const void* headerBuffer, size_t hbSize)210{211 return FSE_readNCount_body(normalizedCounter, maxSVPtr, tableLogPtr, headerBuffer, hbSize);212}213 214#if DYNAMIC_BMI2215BMI2_TARGET_ATTRIBUTE static size_t FSE_readNCount_body_bmi2(216 short* normalizedCounter, unsigned* maxSVPtr, unsigned* tableLogPtr,217 const void* headerBuffer, size_t hbSize)218{219 return FSE_readNCount_body(normalizedCounter, maxSVPtr, tableLogPtr, headerBuffer, hbSize);220}221#endif222 223size_t FSE_readNCount_bmi2(224 short* normalizedCounter, unsigned* maxSVPtr, unsigned* tableLogPtr,225 const void* headerBuffer, size_t hbSize, int bmi2)226{227#if DYNAMIC_BMI2228 if (bmi2) {229 return FSE_readNCount_body_bmi2(normalizedCounter, maxSVPtr, tableLogPtr, headerBuffer, hbSize);230 }231#endif232 (void)bmi2;233 return FSE_readNCount_body_default(normalizedCounter, maxSVPtr, tableLogPtr, headerBuffer, hbSize);234}235 236size_t FSE_readNCount(237 short* normalizedCounter, unsigned* maxSVPtr, unsigned* tableLogPtr,238 const void* headerBuffer, size_t hbSize)239{240 return FSE_readNCount_bmi2(normalizedCounter, maxSVPtr, tableLogPtr, headerBuffer, hbSize, /* bmi2 */ 0);241}242 243 244/*! HUF_readStats() :245 Read compact Huffman tree, saved by HUF_writeCTable().246 `huffWeight` is destination buffer.247 `rankStats` is assumed to be a table of at least HUF_TABLELOG_MAX U32.248 @return : size read from `src` , or an error Code .249 Note : Needed by HUF_readCTable() and HUF_readDTableX?() .250*/251size_t HUF_readStats(BYTE* huffWeight, size_t hwSize, U32* rankStats,252 U32* nbSymbolsPtr, U32* tableLogPtr,253 const void* src, size_t srcSize)254{255 U32 wksp[HUF_READ_STATS_WORKSPACE_SIZE_U32];256 return HUF_readStats_wksp(huffWeight, hwSize, rankStats, nbSymbolsPtr, tableLogPtr, src, srcSize, wksp, sizeof(wksp), /* bmi2 */ 0);257}258 259FORCE_INLINE_TEMPLATE size_t260HUF_readStats_body(BYTE* huffWeight, size_t hwSize, U32* rankStats,261 U32* nbSymbolsPtr, U32* tableLogPtr,262 const void* src, size_t srcSize,263 void* workSpace, size_t wkspSize,264 int bmi2)265{266 U32 weightTotal;267 const BYTE* ip = (const BYTE*) src;268 size_t iSize;269 size_t oSize;270 271 if (!srcSize) return ERROR(srcSize_wrong);272 iSize = ip[0];273 /* ZSTD_memset(huffWeight, 0, hwSize); *//* is not necessary, even though some analyzer complain ... */274 275 if (iSize >= 128) { /* special header */276 oSize = iSize - 127;277 iSize = ((oSize+1)/2);278 if (iSize+1 > srcSize) return ERROR(srcSize_wrong);279 if (oSize >= hwSize) return ERROR(corruption_detected);280 ip += 1;281 { U32 n;282 for (n=0; n<oSize; n+=2) {283 huffWeight[n] = ip[n/2] >> 4;284 huffWeight[n+1] = ip[n/2] & 15;285 } } }286 else { /* header compressed with FSE (normal case) */287 if (iSize+1 > srcSize) return ERROR(srcSize_wrong);288 /* max (hwSize-1) values decoded, as last one is implied */289 oSize = FSE_decompress_wksp_bmi2(huffWeight, hwSize-1, ip+1, iSize, 6, workSpace, wkspSize, bmi2);290 if (FSE_isError(oSize)) return oSize;291 }292 293 /* collect weight stats */294 ZSTD_memset(rankStats, 0, (HUF_TABLELOG_MAX + 1) * sizeof(U32));295 weightTotal = 0;296 { U32 n; for (n=0; n<oSize; n++) {297 if (huffWeight[n] > HUF_TABLELOG_MAX) return ERROR(corruption_detected);298 rankStats[huffWeight[n]]++;299 weightTotal += (1 << huffWeight[n]) >> 1;300 } }301 if (weightTotal == 0) return ERROR(corruption_detected);302 303 /* get last non-null symbol weight (implied, total must be 2^n) */304 { U32 const tableLog = BIT_highbit32(weightTotal) + 1;305 if (tableLog > HUF_TABLELOG_MAX) return ERROR(corruption_detected);306 *tableLogPtr = tableLog;307 /* determine last weight */308 { U32 const total = 1 << tableLog;309 U32 const rest = total - weightTotal;310 U32 const verif = 1 << BIT_highbit32(rest);311 U32 const lastWeight = BIT_highbit32(rest) + 1;312 if (verif != rest) return ERROR(corruption_detected); /* last value must be a clean power of 2 */313 huffWeight[oSize] = (BYTE)lastWeight;314 rankStats[lastWeight]++;315 } }316 317 /* check tree construction validity */318 if ((rankStats[1] < 2) || (rankStats[1] & 1)) return ERROR(corruption_detected); /* by construction : at least 2 elts of rank 1, must be even */319 320 /* results */321 *nbSymbolsPtr = (U32)(oSize+1);322 return iSize+1;323}324 325/* Avoids the FORCE_INLINE of the _body() function. */326static size_t HUF_readStats_body_default(BYTE* huffWeight, size_t hwSize, U32* rankStats,327 U32* nbSymbolsPtr, U32* tableLogPtr,328 const void* src, size_t srcSize,329 void* workSpace, size_t wkspSize)330{331 return HUF_readStats_body(huffWeight, hwSize, rankStats, nbSymbolsPtr, tableLogPtr, src, srcSize, workSpace, wkspSize, 0);332}333 334#if DYNAMIC_BMI2335static BMI2_TARGET_ATTRIBUTE size_t HUF_readStats_body_bmi2(BYTE* huffWeight, size_t hwSize, U32* rankStats,336 U32* nbSymbolsPtr, U32* tableLogPtr,337 const void* src, size_t srcSize,338 void* workSpace, size_t wkspSize)339{340 return HUF_readStats_body(huffWeight, hwSize, rankStats, nbSymbolsPtr, tableLogPtr, src, srcSize, workSpace, wkspSize, 1);341}342#endif343 344size_t HUF_readStats_wksp(BYTE* huffWeight, size_t hwSize, U32* rankStats,345 U32* nbSymbolsPtr, U32* tableLogPtr,346 const void* src, size_t srcSize,347 void* workSpace, size_t wkspSize,348 int bmi2)349{350#if DYNAMIC_BMI2351 if (bmi2) {352 return HUF_readStats_body_bmi2(huffWeight, hwSize, rankStats, nbSymbolsPtr, tableLogPtr, src, srcSize, workSpace, wkspSize);353 }354#endif355 (void)bmi2;356 return HUF_readStats_body_default(huffWeight, hwSize, rankStats, nbSymbolsPtr, tableLogPtr, src, srcSize, workSpace, wkspSize);357}358