1/* ****************************************************************** 2 * FSE : Finite State Entropy encoder 3 * Copyright (c) Yann Collet, Facebook, Inc. 4 * 5 * You can contact the author at : 6 * - FSE 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* Includes 17****************************************************************/ 18#include "../common/compiler.h" 19#include "../common/mem.h" /* U32, U16, etc. */ 20#include "../common/debug.h" /* assert, DEBUGLOG */ 21#include "hist.h" /* HIST_count_wksp */ 22#include "../common/bitstream.h" 23#define FSE_STATIC_LINKING_ONLY 24#include "../common/fse.h" 25#include "../common/error_private.h" 26#define ZSTD_DEPS_NEED_MALLOC 27#define ZSTD_DEPS_NEED_MATH64 28#include "../common/zstd_deps.h" /* ZSTD_malloc, ZSTD_free, ZSTD_memcpy, ZSTD_memset */ 29 30 31/* ************************************************************** 32* Error Management 33****************************************************************/ 34#define FSE_isError ERR_isError 35 36 37/* ************************************************************** 38* Templates 39****************************************************************/ 40/* 41 designed to be included 42 for type-specific functions (template emulation in C) 43 Objective is to write these functions only once, for improved maintenance 44*/ 45 46/* safety checks */ 47#ifndef FSE_FUNCTION_EXTENSION 48# error "FSE_FUNCTION_EXTENSION must be defined" 49#endif 50#ifndef FSE_FUNCTION_TYPE 51# error "FSE_FUNCTION_TYPE must be defined" 52#endif 53 54/* Function names */ 55#define FSE_CAT(X,Y) X##Y 56#define FSE_FUNCTION_NAME(X,Y) FSE_CAT(X,Y) 57#define FSE_TYPE_NAME(X,Y) FSE_CAT(X,Y) 58 59 60/* Function templates */ 61 62/* FSE_buildCTable_wksp() : 63 * Same as FSE_buildCTable(), but using an externally allocated scratch buffer (`workSpace`). 64 * wkspSize should be sized to handle worst case situation, which is `1<<max_tableLog * sizeof(FSE_FUNCTION_TYPE)` 65 * workSpace must also be properly aligned with FSE_FUNCTION_TYPE requirements 66 */ 67size_t FSE_buildCTable_wksp(FSE_CTable* ct, 68 const short* normalizedCounter, unsigned maxSymbolValue, unsigned tableLog, 69 void* workSpace, size_t wkspSize) 70{ 71 U32 const tableSize = 1 << tableLog; 72 U32 const tableMask = tableSize - 1; 73 void* const ptr = ct; 74 U16* const tableU16 = ( (U16*) ptr) + 2; 75 void* const FSCT = ((U32*)ptr) + 1 /* header */ + (tableLog ? tableSize>>1 : 1) ; 76 FSE_symbolCompressionTransform* const symbolTT = (FSE_symbolCompressionTransform*) (FSCT); 77 U32 const step = FSE_TABLESTEP(tableSize); 78 U32 const maxSV1 = maxSymbolValue+1; 79 80 U16* cumul = (U16*)workSpace; /* size = maxSV1 */ 81 FSE_FUNCTION_TYPE* const tableSymbol = (FSE_FUNCTION_TYPE*)(cumul + (maxSV1+1)); /* size = tableSize */ 82 83 U32 highThreshold = tableSize-1; 84 85 assert(((size_t)workSpace & 1) == 0); /* Must be 2 bytes-aligned */ 86 if (FSE_BUILD_CTABLE_WORKSPACE_SIZE(maxSymbolValue, tableLog) > wkspSize) return ERROR(tableLog_tooLarge); 87 /* CTable header */ 88 tableU16[-2] = (U16) tableLog; 89 tableU16[-1] = (U16) maxSymbolValue; 90 assert(tableLog < 16); /* required for threshold strategy to work */ 91 92 /* For explanations on how to distribute symbol values over the table : 93 * http://fastcompression.blogspot.fr/2014/02/fse-distributing-symbol-values.html */ 94 95 #ifdef __clang_analyzer__ 96 ZSTD_memset(tableSymbol, 0, sizeof(*tableSymbol) * tableSize); /* useless initialization, just to keep scan-build happy */ 97 #endif 98 99 /* symbol start positions */ 100 { U32 u; 101 cumul[0] = 0; 102 for (u=1; u <= maxSV1; u++) { 103 if (normalizedCounter[u-1]==-1) { /* Low proba symbol */ 104 cumul[u] = cumul[u-1] + 1; 105 tableSymbol[highThreshold--] = (FSE_FUNCTION_TYPE)(u-1); 106 } else { 107 assert(normalizedCounter[u-1] >= 0); 108 cumul[u] = cumul[u-1] + (U16)normalizedCounter[u-1]; 109 assert(cumul[u] >= cumul[u-1]); /* no overflow */ 110 } } 111 cumul[maxSV1] = (U16)(tableSize+1); 112 } 113 114 /* Spread symbols */ 115 if (highThreshold == tableSize - 1) { 116 /* Case for no low prob count symbols. Lay down 8 bytes at a time 117 * to reduce branch misses since we are operating on a small block 118 */ 119 BYTE* const spread = tableSymbol + tableSize; /* size = tableSize + 8 (may write beyond tableSize) */ 120 { U64 const add = 0x0101010101010101ull; 121 size_t pos = 0; 122 U64 sv = 0; 123 U32 s; 124 for (s=0; s<maxSV1; ++s, sv += add) { 125 int i; 126 int const n = normalizedCounter[s]; 127 MEM_write64(spread + pos, sv); 128 for (i = 8; i < n; i += 8) { 129 MEM_write64(spread + pos + i, sv); 130 } 131 assert(n>=0); 132 pos += (size_t)n; 133 } 134 } 135 /* Spread symbols across the table. Lack of lowprob symbols means that 136 * we don't need variable sized inner loop, so we can unroll the loop and 137 * reduce branch misses. 138 */ 139 { size_t position = 0; 140 size_t s; 141 size_t const unroll = 2; /* Experimentally determined optimal unroll */ 142 assert(tableSize % unroll == 0); /* FSE_MIN_TABLELOG is 5 */ 143 for (s = 0; s < (size_t)tableSize; s += unroll) { 144 size_t u; 145 for (u = 0; u < unroll; ++u) { 146 size_t const uPosition = (position + (u * step)) & tableMask; 147 tableSymbol[uPosition] = spread[s + u]; 148 } 149 position = (position + (unroll * step)) & tableMask; 150 } 151 assert(position == 0); /* Must have initialized all positions */ 152 } 153 } else { 154 U32 position = 0; 155 U32 symbol; 156 for (symbol=0; symbol<maxSV1; symbol++) { 157 int nbOccurrences; 158 int const freq = normalizedCounter[symbol]; 159 for (nbOccurrences=0; nbOccurrences<freq; nbOccurrences++) { 160 tableSymbol[position] = (FSE_FUNCTION_TYPE)symbol; 161 position = (position + step) & tableMask; 162 while (position > highThreshold) 163 position = (position + step) & tableMask; /* Low proba area */ 164 } } 165 assert(position==0); /* Must have initialized all positions */ 166 } 167 168 /* Build table */ 169 { U32 u; for (u=0; u<tableSize; u++) { 170 FSE_FUNCTION_TYPE s = tableSymbol[u]; /* note : static analyzer may not understand tableSymbol is properly initialized */ 171 tableU16[cumul[s]++] = (U16) (tableSize+u); /* TableU16 : sorted by symbol order; gives next state value */ 172 } } 173 174 /* Build Symbol Transformation Table */ 175 { unsigned total = 0; 176 unsigned s; 177 for (s=0; s<=maxSymbolValue; s++) { 178 switch (normalizedCounter[s]) 179 { 180 case 0: 181 /* filling nonetheless, for compatibility with FSE_getMaxNbBits() */ 182 symbolTT[s].deltaNbBits = ((tableLog+1) << 16) - (1<<tableLog); 183 break; 184 185 case -1: 186 case 1: 187 symbolTT[s].deltaNbBits = (tableLog << 16) - (1<<tableLog); 188 assert(total <= INT_MAX); 189 symbolTT[s].deltaFindState = (int)(total - 1); 190 total ++; 191 break; 192 default : 193 assert(normalizedCounter[s] > 1); 194 { U32 const maxBitsOut = tableLog - BIT_highbit32 ((U32)normalizedCounter[s]-1); 195 U32 const minStatePlus = (U32)normalizedCounter[s] << maxBitsOut; 196 symbolTT[s].deltaNbBits = (maxBitsOut << 16) - minStatePlus; 197 symbolTT[s].deltaFindState = (int)(total - (unsigned)normalizedCounter[s]); 198 total += (unsigned)normalizedCounter[s]; 199 } } } } 200 201#if 0 /* debug : symbol costs */ 202 DEBUGLOG(5, "\n --- table statistics : "); 203 { U32 symbol; 204 for (symbol=0; symbol<=maxSymbolValue; symbol++) { 205 DEBUGLOG(5, "%3u: w=%3i, maxBits=%u, fracBits=%.2f", 206 symbol, normalizedCounter[symbol], 207 FSE_getMaxNbBits(symbolTT, symbol), 208 (double)FSE_bitCost(symbolTT, tableLog, symbol, 8) / 256); 209 } } 210#endif 211 212 return 0; 213} 214 215 216 217#ifndef FSE_COMMONDEFS_ONLY 218 219/*-************************************************************** 220* FSE NCount encoding 221****************************************************************/ 222size_t FSE_NCountWriteBound(unsigned maxSymbolValue, unsigned tableLog) 223{ 224 size_t const maxHeaderSize = (((maxSymbolValue+1) * tableLog 225 + 4 /* bitCount initialized at 4 */ 226 + 2 /* first two symbols may use one additional bit each */) / 8) 227 + 1 /* round up to whole nb bytes */ 228 + 2 /* additional two bytes for bitstream flush */; 229 return maxSymbolValue ? maxHeaderSize : FSE_NCOUNTBOUND; /* maxSymbolValue==0 ? use default */ 230} 231 232static size_t 233FSE_writeNCount_generic (void* header, size_t headerBufferSize, 234 const short* normalizedCounter, unsigned maxSymbolValue, unsigned tableLog, 235 unsigned writeIsSafe) 236{ 237 BYTE* const ostart = (BYTE*) header; 238 BYTE* out = ostart; 239 BYTE* const oend = ostart + headerBufferSize; 240 int nbBits; 241 const int tableSize = 1 << tableLog; 242 int remaining; 243 int threshold; 244 U32 bitStream = 0; 245 int bitCount = 0; 246 unsigned symbol = 0; 247 unsigned const alphabetSize = maxSymbolValue + 1; 248 int previousIs0 = 0; 249 250 /* Table Size */ 251 bitStream += (tableLog-FSE_MIN_TABLELOG) << bitCount; 252 bitCount += 4; 253 254 /* Init */ 255 remaining = tableSize+1; /* +1 for extra accuracy */ 256 threshold = tableSize; 257 nbBits = tableLog+1; 258 259 while ((symbol < alphabetSize) && (remaining>1)) { /* stops at 1 */ 260 if (previousIs0) { 261 unsigned start = symbol; 262 while ((symbol < alphabetSize) && !normalizedCounter[symbol]) symbol++; 263 if (symbol == alphabetSize) break; /* incorrect distribution */ 264 while (symbol >= start+24) { 265 start+=24; 266 bitStream += 0xFFFFU << bitCount; 267 if ((!writeIsSafe) && (out > oend-2)) 268 return ERROR(dstSize_tooSmall); /* Buffer overflow */ 269 out[0] = (BYTE) bitStream; 270 out[1] = (BYTE)(bitStream>>8); 271 out+=2; 272 bitStream>>=16; 273 } 274 while (symbol >= start+3) { 275 start+=3; 276 bitStream += 3 << bitCount; 277 bitCount += 2; 278 } 279 bitStream += (symbol-start) << bitCount; 280 bitCount += 2; 281 if (bitCount>16) { 282 if ((!writeIsSafe) && (out > oend - 2)) 283 return ERROR(dstSize_tooSmall); /* Buffer overflow */ 284 out[0] = (BYTE)bitStream; 285 out[1] = (BYTE)(bitStream>>8); 286 out += 2; 287 bitStream >>= 16; 288 bitCount -= 16; 289 } } 290 { int count = normalizedCounter[symbol++]; 291 int const max = (2*threshold-1) - remaining; 292 remaining -= count < 0 ? -count : count; 293 count++; /* +1 for extra accuracy */ 294 if (count>=threshold) 295 count += max; /* [0..max[ [max..threshold[ (...) [threshold+max 2*threshold[ */ 296 bitStream += count << bitCount; 297 bitCount += nbBits; 298 bitCount -= (count<max); 299 previousIs0 = (count==1); 300 if (remaining<1) return ERROR(GENERIC); 301 while (remaining<threshold) { nbBits--; threshold>>=1; } 302 } 303 if (bitCount>16) { 304 if ((!writeIsSafe) && (out > oend - 2)) 305 return ERROR(dstSize_tooSmall); /* Buffer overflow */ 306 out[0] = (BYTE)bitStream; 307 out[1] = (BYTE)(bitStream>>8); 308 out += 2; 309 bitStream >>= 16; 310 bitCount -= 16; 311 } } 312 313 if (remaining != 1) 314 return ERROR(GENERIC); /* incorrect normalized distribution */ 315 assert(symbol <= alphabetSize); 316 317 /* flush remaining bitStream */ 318 if ((!writeIsSafe) && (out > oend - 2)) 319 return ERROR(dstSize_tooSmall); /* Buffer overflow */ 320 out[0] = (BYTE)bitStream; 321 out[1] = (BYTE)(bitStream>>8); 322 out+= (bitCount+7) /8; 323 324 return (out-ostart); 325} 326 327 328size_t FSE_writeNCount (void* buffer, size_t bufferSize, 329 const short* normalizedCounter, unsigned maxSymbolValue, unsigned tableLog) 330{ 331 if (tableLog > FSE_MAX_TABLELOG) return ERROR(tableLog_tooLarge); /* Unsupported */ 332 if (tableLog < FSE_MIN_TABLELOG) return ERROR(GENERIC); /* Unsupported */ 333 334 if (bufferSize < FSE_NCountWriteBound(maxSymbolValue, tableLog)) 335 return FSE_writeNCount_generic(buffer, bufferSize, normalizedCounter, maxSymbolValue, tableLog, 0); 336 337 return FSE_writeNCount_generic(buffer, bufferSize, normalizedCounter, maxSymbolValue, tableLog, 1 /* write in buffer is safe */); 338} 339 340 341/*-************************************************************** 342* FSE Compression Code 343****************************************************************/ 344 345FSE_CTable* FSE_createCTable (unsigned maxSymbolValue, unsigned tableLog) 346{ 347 size_t size; 348 if (tableLog > FSE_TABLELOG_ABSOLUTE_MAX) tableLog = FSE_TABLELOG_ABSOLUTE_MAX; 349 size = FSE_CTABLE_SIZE_U32 (tableLog, maxSymbolValue) * sizeof(U32); 350 return (FSE_CTable*)ZSTD_malloc(size); 351} 352 353void FSE_freeCTable (FSE_CTable* ct) { ZSTD_free(ct); } 354 355/* provides the minimum logSize to safely represent a distribution */ 356static unsigned FSE_minTableLog(size_t srcSize, unsigned maxSymbolValue) 357{ 358 U32 minBitsSrc = BIT_highbit32((U32)(srcSize)) + 1; 359 U32 minBitsSymbols = BIT_highbit32(maxSymbolValue) + 2; 360 U32 minBits = minBitsSrc < minBitsSymbols ? minBitsSrc : minBitsSymbols; 361 assert(srcSize > 1); /* Not supported, RLE should be used instead */ 362 return minBits; 363} 364 365unsigned FSE_optimalTableLog_internal(unsigned maxTableLog, size_t srcSize, unsigned maxSymbolValue, unsigned minus) 366{ 367 U32 maxBitsSrc = BIT_highbit32((U32)(srcSize - 1)) - minus; 368 U32 tableLog = maxTableLog; 369 U32 minBits = FSE_minTableLog(srcSize, maxSymbolValue); 370 assert(srcSize > 1); /* Not supported, RLE should be used instead */ 371 if (tableLog==0) tableLog = FSE_DEFAULT_TABLELOG; 372 if (maxBitsSrc < tableLog) tableLog = maxBitsSrc; /* Accuracy can be reduced */ 373 if (minBits > tableLog) tableLog = minBits; /* Need a minimum to safely represent all symbol values */ 374 if (tableLog < FSE_MIN_TABLELOG) tableLog = FSE_MIN_TABLELOG; 375 if (tableLog > FSE_MAX_TABLELOG) tableLog = FSE_MAX_TABLELOG; 376 return tableLog; 377} 378 379unsigned FSE_optimalTableLog(unsigned maxTableLog, size_t srcSize, unsigned maxSymbolValue) 380{ 381 return FSE_optimalTableLog_internal(maxTableLog, srcSize, maxSymbolValue, 2); 382} 383 384/* Secondary normalization method. 385 To be used when primary method fails. */ 386 387static size_t FSE_normalizeM2(short* norm, U32 tableLog, const unsigned* count, size_t total, U32 maxSymbolValue, short lowProbCount) 388{ 389 short const NOT_YET_ASSIGNED = -2; 390 U32 s; 391 U32 distributed = 0; 392 U32 ToDistribute; 393 394 /* Init */ 395 U32 const lowThreshold = (U32)(total >> tableLog); 396 U32 lowOne = (U32)((total * 3) >> (tableLog + 1)); 397 398 for (s=0; s<=maxSymbolValue; s++) { 399 if (count[s] == 0) { 400 norm[s]=0; 401 continue; 402 } 403 if (count[s] <= lowThreshold) { 404 norm[s] = lowProbCount; 405 distributed++; 406 total -= count[s]; 407 continue; 408 } 409 if (count[s] <= lowOne) { 410 norm[s] = 1; 411 distributed++; 412 total -= count[s]; 413 continue; 414 } 415 416 norm[s]=NOT_YET_ASSIGNED; 417 } 418 ToDistribute = (1 << tableLog) - distributed; 419 420 if (ToDistribute == 0) 421 return 0; 422 423 if ((total / ToDistribute) > lowOne) { 424 /* risk of rounding to zero */ 425 lowOne = (U32)((total * 3) / (ToDistribute * 2)); 426 for (s=0; s<=maxSymbolValue; s++) { 427 if ((norm[s] == NOT_YET_ASSIGNED) && (count[s] <= lowOne)) { 428 norm[s] = 1; 429 distributed++; 430 total -= count[s]; 431 continue; 432 } } 433 ToDistribute = (1 << tableLog) - distributed; 434 } 435 436 if (distributed == maxSymbolValue+1) { 437 /* all values are pretty poor; 438 probably incompressible data (should have already been detected); 439 find max, then give all remaining points to max */ 440 U32 maxV = 0, maxC = 0; 441 for (s=0; s<=maxSymbolValue; s++) 442 if (count[s] > maxC) { maxV=s; maxC=count[s]; } 443 norm[maxV] += (short)ToDistribute; 444 return 0; 445 } 446 447 if (total == 0) { 448 /* all of the symbols were low enough for the lowOne or lowThreshold */ 449 for (s=0; ToDistribute > 0; s = (s+1)%(maxSymbolValue+1)) 450 if (norm[s] > 0) { ToDistribute--; norm[s]++; } 451 return 0; 452 } 453 454 { U64 const vStepLog = 62 - tableLog; 455 U64 const mid = (1ULL << (vStepLog-1)) - 1; 456 U64 const rStep = ZSTD_div64((((U64)1<<vStepLog) * ToDistribute) + mid, (U32)total); /* scale on remaining */ 457 U64 tmpTotal = mid; 458 for (s=0; s<=maxSymbolValue; s++) { 459 if (norm[s]==NOT_YET_ASSIGNED) { 460 U64 const end = tmpTotal + (count[s] * rStep); 461 U32 const sStart = (U32)(tmpTotal >> vStepLog); 462 U32 const sEnd = (U32)(end >> vStepLog); 463 U32 const weight = sEnd - sStart; 464 if (weight < 1) 465 return ERROR(GENERIC); 466 norm[s] = (short)weight; 467 tmpTotal = end; 468 } } } 469 470 return 0; 471} 472 473size_t FSE_normalizeCount (short* normalizedCounter, unsigned tableLog, 474 const unsigned* count, size_t total, 475 unsigned maxSymbolValue, unsigned useLowProbCount) 476{ 477 /* Sanity checks */ 478 if (tableLog==0) tableLog = FSE_DEFAULT_TABLELOG; 479 if (tableLog < FSE_MIN_TABLELOG) return ERROR(GENERIC); /* Unsupported size */ 480 if (tableLog > FSE_MAX_TABLELOG) return ERROR(tableLog_tooLarge); /* Unsupported size */ 481 if (tableLog < FSE_minTableLog(total, maxSymbolValue)) return ERROR(GENERIC); /* Too small tableLog, compression potentially impossible */ 482 483 { static U32 const rtbTable[] = { 0, 473195, 504333, 520860, 550000, 700000, 750000, 830000 }; 484 short const lowProbCount = useLowProbCount ? -1 : 1; 485 U64 const scale = 62 - tableLog; 486 U64 const step = ZSTD_div64((U64)1<<62, (U32)total); /* <== here, one division ! */ 487 U64 const vStep = 1ULL<<(scale-20); 488 int stillToDistribute = 1<<tableLog; 489 unsigned s; 490 unsigned largest=0; 491 short largestP=0; 492 U32 lowThreshold = (U32)(total >> tableLog); 493 494 for (s=0; s<=maxSymbolValue; s++) { 495 if (count[s] == total) return 0; /* rle special case */ 496 if (count[s] == 0) { normalizedCounter[s]=0; continue; } 497 if (count[s] <= lowThreshold) { 498 normalizedCounter[s] = lowProbCount; 499 stillToDistribute--; 500 } else { 501 short proba = (short)((count[s]*step) >> scale); 502 if (proba<8) { 503 U64 restToBeat = vStep * rtbTable[proba]; 504 proba += (count[s]*step) - ((U64)proba<<scale) > restToBeat; 505 } 506 if (proba > largestP) { largestP=proba; largest=s; } 507 normalizedCounter[s] = proba; 508 stillToDistribute -= proba; 509 } } 510 if (-stillToDistribute >= (normalizedCounter[largest] >> 1)) { 511 /* corner case, need another normalization method */ 512 size_t const errorCode = FSE_normalizeM2(normalizedCounter, tableLog, count, total, maxSymbolValue, lowProbCount); 513 if (FSE_isError(errorCode)) return errorCode; 514 } 515 else normalizedCounter[largest] += (short)stillToDistribute; 516 } 517 518#if 0 519 { /* Print Table (debug) */ 520 U32 s; 521 U32 nTotal = 0; 522 for (s=0; s<=maxSymbolValue; s++) 523 RAWLOG(2, "%3i: %4i \n", s, normalizedCounter[s]); 524 for (s=0; s<=maxSymbolValue; s++) 525 nTotal += abs(normalizedCounter[s]); 526 if (nTotal != (1U<<tableLog)) 527 RAWLOG(2, "Warning !!! Total == %u != %u !!!", nTotal, 1U<<tableLog); 528 getchar(); 529 } 530#endif 531 532 return tableLog; 533} 534 535 536/* fake FSE_CTable, for raw (uncompressed) input */ 537size_t FSE_buildCTable_raw (FSE_CTable* ct, unsigned nbBits) 538{ 539 const unsigned tableSize = 1 << nbBits; 540 const unsigned tableMask = tableSize - 1; 541 const unsigned maxSymbolValue = tableMask; 542 void* const ptr = ct; 543 U16* const tableU16 = ( (U16*) ptr) + 2; 544 void* const FSCT = ((U32*)ptr) + 1 /* header */ + (tableSize>>1); /* assumption : tableLog >= 1 */ 545 FSE_symbolCompressionTransform* const symbolTT = (FSE_symbolCompressionTransform*) (FSCT); 546 unsigned s; 547 548 /* Sanity checks */ 549 if (nbBits < 1) return ERROR(GENERIC); /* min size */ 550 551 /* header */ 552 tableU16[-2] = (U16) nbBits; 553 tableU16[-1] = (U16) maxSymbolValue; 554 555 /* Build table */ 556 for (s=0; s<tableSize; s++) 557 tableU16[s] = (U16)(tableSize + s); 558 559 /* Build Symbol Transformation Table */ 560 { const U32 deltaNbBits = (nbBits << 16) - (1 << nbBits); 561 for (s=0; s<=maxSymbolValue; s++) { 562 symbolTT[s].deltaNbBits = deltaNbBits; 563 symbolTT[s].deltaFindState = s-1; 564 } } 565 566 return 0; 567} 568 569/* fake FSE_CTable, for rle input (always same symbol) */ 570size_t FSE_buildCTable_rle (FSE_CTable* ct, BYTE symbolValue) 571{ 572 void* ptr = ct; 573 U16* tableU16 = ( (U16*) ptr) + 2; 574 void* FSCTptr = (U32*)ptr + 2; 575 FSE_symbolCompressionTransform* symbolTT = (FSE_symbolCompressionTransform*) FSCTptr; 576 577 /* header */ 578 tableU16[-2] = (U16) 0; 579 tableU16[-1] = (U16) symbolValue; 580 581 /* Build table */ 582 tableU16[0] = 0; 583 tableU16[1] = 0; /* just in case */ 584 585 /* Build Symbol Transformation Table */ 586 symbolTT[symbolValue].deltaNbBits = 0; 587 symbolTT[symbolValue].deltaFindState = 0; 588 589 return 0; 590} 591 592 593static size_t FSE_compress_usingCTable_generic (void* dst, size_t dstSize, 594 const void* src, size_t srcSize, 595 const FSE_CTable* ct, const unsigned fast) 596{ 597 const BYTE* const istart = (const BYTE*) src; 598 const BYTE* const iend = istart + srcSize; 599 const BYTE* ip=iend; 600 601 BIT_CStream_t bitC; 602 FSE_CState_t CState1, CState2; 603 604 /* init */ 605 if (srcSize <= 2) return 0; 606 { size_t const initError = BIT_initCStream(&bitC, dst, dstSize); 607 if (FSE_isError(initError)) return 0; /* not enough space available to write a bitstream */ } 608 609#define FSE_FLUSHBITS(s) (fast ? BIT_flushBitsFast(s) : BIT_flushBits(s)) 610 611 if (srcSize & 1) { 612 FSE_initCState2(&CState1, ct, *--ip); 613 FSE_initCState2(&CState2, ct, *--ip); 614 FSE_encodeSymbol(&bitC, &CState1, *--ip); 615 FSE_FLUSHBITS(&bitC); 616 } else { 617 FSE_initCState2(&CState2, ct, *--ip); 618 FSE_initCState2(&CState1, ct, *--ip); 619 } 620 621 /* join to mod 4 */ 622 srcSize -= 2; 623 if ((sizeof(bitC.bitContainer)*8 > FSE_MAX_TABLELOG*4+7 ) && (srcSize & 2)) { /* test bit 2 */ 624 FSE_encodeSymbol(&bitC, &CState2, *--ip); 625 FSE_encodeSymbol(&bitC, &CState1, *--ip); 626 FSE_FLUSHBITS(&bitC); 627 } 628 629 /* 2 or 4 encoding per loop */ 630 while ( ip>istart ) { 631 632 FSE_encodeSymbol(&bitC, &CState2, *--ip); 633 634 if (sizeof(bitC.bitContainer)*8 < FSE_MAX_TABLELOG*2+7 ) /* this test must be static */ 635 FSE_FLUSHBITS(&bitC); 636 637 FSE_encodeSymbol(&bitC, &CState1, *--ip); 638 639 if (sizeof(bitC.bitContainer)*8 > FSE_MAX_TABLELOG*4+7 ) { /* this test must be static */ 640 FSE_encodeSymbol(&bitC, &CState2, *--ip); 641 FSE_encodeSymbol(&bitC, &CState1, *--ip); 642 } 643 644 FSE_FLUSHBITS(&bitC); 645 } 646 647 FSE_flushCState(&bitC, &CState2); 648 FSE_flushCState(&bitC, &CState1); 649 return BIT_closeCStream(&bitC); 650} 651 652size_t FSE_compress_usingCTable (void* dst, size_t dstSize, 653 const void* src, size_t srcSize, 654 const FSE_CTable* ct) 655{ 656 unsigned const fast = (dstSize >= FSE_BLOCKBOUND(srcSize)); 657 658 if (fast) 659 return FSE_compress_usingCTable_generic(dst, dstSize, src, srcSize, ct, 1); 660 else 661 return FSE_compress_usingCTable_generic(dst, dstSize, src, srcSize, ct, 0); 662} 663 664 665size_t FSE_compressBound(size_t size) { return FSE_COMPRESSBOUND(size); } 666 667 668#endif /* FSE_COMMONDEFS_ONLY */ 669