git.sesse.net Git - bcachefs-tools-debian/blob - linux/lz4_compress.c

   1 /*
   2  * LZ4 - Fast LZ compression algorithm
   3  * Copyright (C) 2011 - 2016, Yann Collet.
   4  * BSD 2 - Clause License (http://www.opensource.org/licenses/bsd - license.php)
   5  * Redistribution and use in source and binary forms, with or without
   6  * modification, are permitted provided that the following conditions are
   7  * met:
   8  *      * Redistributions of source code must retain the above copyright
   9  *        notice, this list of conditions and the following disclaimer.
  10  *      * Redistributions in binary form must reproduce the above
  11  * copyright notice, this list of conditions and the following disclaimer
  12  * in the documentation and/or other materials provided with the
  13  * distribution.
  14  * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
  15  * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
  16  * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
  17  * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
  18  * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
  19  * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
  20  * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
  21  * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
  22  * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
  23  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
  24  * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  25  * You can contact the author at :
  26  *      - LZ4 homepage : http://www.lz4.org
  27  *      - LZ4 source repository : https://github.com/lz4/lz4
  28  *
  29  *      Changed for kernel usage by:
  30  *      Sven Schmidt <4sschmid@informatik.uni-hamburg.de>
  31  */
  32
  33 /*-************************************
  34  *      Dependencies
  35  **************************************/
  36 #include <linux/lz4.h>
  37 #include "lz4defs.h"
  38 #include <linux/kernel.h>
  39 #include <asm/unaligned.h>
  40
  41 static const int LZ4_minLength = (MFLIMIT + 1);
  42 static const int LZ4_64Klimit = ((64 * KB) + (MFLIMIT - 1));
  43
  44 /*-******************************
  45  *      Compression functions
  46  ********************************/
  47 static FORCE_INLINE U32 LZ4_hash4(
  48         U32 sequence,
  49         tableType_t const tableType)
  50 {
  51         if (tableType == byU16)
  52                 return ((sequence * 2654435761U)
  53                         >> ((MINMATCH * 8) - (LZ4_HASHLOG + 1)));
  54         else
  55                 return ((sequence * 2654435761U)
  56                         >> ((MINMATCH * 8) - LZ4_HASHLOG));
  57 }
  58
  59 static FORCE_INLINE U32 LZ4_hash5(
  60         U64 sequence,
  61         tableType_t const tableType)
  62 {
  63         const U32 hashLog = (tableType == byU16)
  64                 ? LZ4_HASHLOG + 1
  65                 : LZ4_HASHLOG;
  66
  67 #if LZ4_LITTLE_ENDIAN
  68         static const U64 prime5bytes = 889523592379ULL;
  69
  70         return (U32)(((sequence << 24) * prime5bytes) >> (64 - hashLog));
  71 #else
  72         static const U64 prime8bytes = 11400714785074694791ULL;
  73
  74         return (U32)(((sequence >> 24) * prime8bytes) >> (64 - hashLog));
  75 #endif
  76 }
  77
  78 static FORCE_INLINE U32 LZ4_hashPosition(
  79         const void *p,
  80         tableType_t const tableType)
  81 {
  82 #if LZ4_ARCH64
  83         if (tableType == byU32)
  84                 return LZ4_hash5(LZ4_read_ARCH(p), tableType);
  85 #endif
  86
  87         return LZ4_hash4(LZ4_read32(p), tableType);
  88 }
  89
  90 static void LZ4_putPositionOnHash(
  91         const BYTE *p,
  92         U32 h,
  93         void *tableBase,
  94         tableType_t const tableType,
  95         const BYTE *srcBase)
  96 {
  97         switch (tableType) {
  98         case byPtr:
  99         {
 100                 const BYTE **hashTable = (const BYTE **)tableBase;
 101
 102                 hashTable[h] = p;
 103                 return;
 104         }
 105         case byU32:
 106         {
 107                 U32 *hashTable = (U32 *) tableBase;
 108
 109                 hashTable[h] = (U32)(p - srcBase);
 110                 return;
 111         }
 112         case byU16:
 113         {
 114                 U16 *hashTable = (U16 *) tableBase;
 115
 116                 hashTable[h] = (U16)(p - srcBase);
 117                 return;
 118         }
 119         }
 120 }
 121
 122 static FORCE_INLINE void LZ4_putPosition(
 123         const BYTE *p,
 124         void *tableBase,
 125         tableType_t tableType,
 126         const BYTE *srcBase)
 127 {
 128         U32 const h = LZ4_hashPosition(p, tableType);
 129
 130         LZ4_putPositionOnHash(p, h, tableBase, tableType, srcBase);
 131 }
 132
 133 static const BYTE *LZ4_getPositionOnHash(
 134         U32 h,
 135         void *tableBase,
 136         tableType_t tableType,
 137         const BYTE *srcBase)
 138 {
 139         if (tableType == byPtr) {
 140                 const BYTE **hashTable = (const BYTE **) tableBase;
 141
 142                 return hashTable[h];
 143         }
 144
 145         if (tableType == byU32) {
 146                 const U32 * const hashTable = (U32 *) tableBase;
 147
 148                 return hashTable[h] + srcBase;
 149         }
 150
 151         {
 152                 /* default, to ensure a return */
 153                 const U16 * const hashTable = (U16 *) tableBase;
 154
 155                 return hashTable[h] + srcBase;
 156         }
 157 }
 158
 159 static FORCE_INLINE const BYTE *LZ4_getPosition(
 160         const BYTE *p,
 161         void *tableBase,
 162         tableType_t tableType,
 163         const BYTE *srcBase)
 164 {
 165         U32 const h = LZ4_hashPosition(p, tableType);
 166
 167         return LZ4_getPositionOnHash(h, tableBase, tableType, srcBase);
 168 }
 169
 170
 171 /*
 172  * LZ4_compress_generic() :
 173  * inlined, to ensure branches are decided at compilation time
 174  */
 175 static FORCE_INLINE int LZ4_compress_generic(
 176         LZ4_stream_t_internal * const dictPtr,
 177         const char * const source,
 178         char * const dest,
 179         const int inputSize,
 180         const int maxOutputSize,
 181         const limitedOutput_directive outputLimited,
 182         const tableType_t tableType,
 183         const dict_directive dict,
 184         const dictIssue_directive dictIssue,
 185         const U32 acceleration)
 186 {
 187         const BYTE *ip = (const BYTE *) source;
 188         const BYTE *base;
 189         const BYTE *lowLimit;
 190         const BYTE * const lowRefLimit = ip - dictPtr->dictSize;
 191         const BYTE * const dictionary = dictPtr->dictionary;
 192         const BYTE * const dictEnd = dictionary + dictPtr->dictSize;
 193         const size_t dictDelta = dictEnd - (const BYTE *)source;
 194         const BYTE *anchor = (const BYTE *) source;
 195         const BYTE * const iend = ip + inputSize;
 196         const BYTE * const mflimit = iend - MFLIMIT;
 197         const BYTE * const matchlimit = iend - LASTLITERALS;
 198
 199         BYTE *op = (BYTE *) dest;
 200         BYTE * const olimit = op + maxOutputSize;
 201
 202         U32 forwardH;
 203         size_t refDelta = 0;
 204
 205         /* Init conditions */
 206         if ((U32)inputSize > (U32)LZ4_MAX_INPUT_SIZE) {
 207                 /* Unsupported inputSize, too large (or negative) */
 208                 return 0;
 209         }
 210
 211         switch (dict) {
 212         case noDict:
 213         default:
 214                 base = (const BYTE *)source;
 215                 lowLimit = (const BYTE *)source;
 216                 break;
 217         case withPrefix64k:
 218                 base = (const BYTE *)source - dictPtr->currentOffset;
 219                 lowLimit = (const BYTE *)source - dictPtr->dictSize;
 220                 break;
 221         case usingExtDict:
 222                 base = (const BYTE *)source - dictPtr->currentOffset;
 223                 lowLimit = (const BYTE *)source;
 224                 break;
 225         }
 226
 227         if ((tableType == byU16)
 228                 && (inputSize >= LZ4_64Klimit)) {
 229                 /* Size too large (not within 64K limit) */
 230                 return 0;
 231         }
 232
 233         if (inputSize < LZ4_minLength) {
 234                 /* Input too small, no compression (all literals) */
 235                 goto _last_literals;
 236         }
 237
 238         /* First Byte */
 239         LZ4_putPosition(ip, dictPtr->hashTable, tableType, base);
 240         ip++;
 241         forwardH = LZ4_hashPosition(ip, tableType);
 242
 243         /* Main Loop */
 244         for ( ; ; ) {
 245                 const BYTE *match;
 246                 BYTE *token;
 247
 248                 /* Find a match */
 249                 {
 250                         const BYTE *forwardIp = ip;
 251                         unsigned int step = 1;
 252                         unsigned int searchMatchNb = acceleration << LZ4_SKIPTRIGGER;
 253
 254                         do {
 255                                 U32 const h = forwardH;
 256
 257                                 ip = forwardIp;
 258                                 forwardIp += step;
 259                                 step = (searchMatchNb++ >> LZ4_SKIPTRIGGER);
 260
 261                                 if (unlikely(forwardIp > mflimit))
 262                                         goto _last_literals;
 263
 264                                 match = LZ4_getPositionOnHash(h,
 265                                         dictPtr->hashTable,
 266                                         tableType, base);
 267
 268                                 if (dict == usingExtDict) {
 269                                         if (match < (const BYTE *)source) {
 270                                                 refDelta = dictDelta;
 271                                                 lowLimit = dictionary;
 272                                         } else {
 273                                                 refDelta = 0;
 274                                                 lowLimit = (const BYTE *)source;
 275                                 }        }
 276
 277                                 forwardH = LZ4_hashPosition(forwardIp,
 278                                         tableType);
 279
 280                                 LZ4_putPositionOnHash(ip, h, dictPtr->hashTable,
 281                                         tableType, base);
 282                         } while (((dictIssue == dictSmall)
 283                                         ? (match < lowRefLimit)
 284                                         : 0)
 285                                 || ((tableType == byU16)
 286                                         ? 0
 287                                         : (match + MAX_DISTANCE < ip))
 288                                 || (LZ4_read32(match + refDelta)
 289                                         != LZ4_read32(ip)));
 290                 }
 291
 292                 /* Catch up */
 293                 while (((ip > anchor) & (match + refDelta > lowLimit))
 294                                 && (unlikely(ip[-1] == match[refDelta - 1]))) {
 295                         ip--;
 296                         match--;
 297                 }
 298
 299                 /* Encode Literals */
 300                 {
 301                         unsigned const int litLength = (unsigned int)(ip - anchor);
 302
 303                         token = op++;
 304
 305                         if ((outputLimited) &&
 306                                 /* Check output buffer overflow */
 307                                 (unlikely(op + litLength +
 308                                         (2 + 1 + LASTLITERALS) +
 309                                         (litLength / 255) > olimit)))
 310                                 return 0;
 311
 312                         if (litLength >= RUN_MASK) {
 313                                 int len = (int)litLength - RUN_MASK;
 314
 315                                 *token = (RUN_MASK << ML_BITS);
 316
 317                                 for (; len >= 255; len -= 255)
 318                                         *op++ = 255;
 319                                 *op++ = (BYTE)len;
 320                         } else
 321                                 *token = (BYTE)(litLength << ML_BITS);
 322
 323                         /* Copy Literals */
 324                         LZ4_wildCopy(op, anchor, op + litLength);
 325                         op += litLength;
 326                 }
 327
 328 _next_match:
 329                 /* Encode Offset */
 330                 LZ4_writeLE16(op, (U16)(ip - match));
 331                 op += 2;
 332
 333                 /* Encode MatchLength */
 334                 {
 335                         unsigned int matchCode;
 336
 337                         if ((dict == usingExtDict)
 338                                 && (lowLimit == dictionary)) {
 339                                 const BYTE *limit;
 340
 341                                 match += refDelta;
 342                                 limit = ip + (dictEnd - match);
 343
 344                                 if (limit > matchlimit)
 345                                         limit = matchlimit;
 346
 347                                 matchCode = LZ4_count(ip + MINMATCH,
 348                                         match + MINMATCH, limit);
 349
 350                                 ip += MINMATCH + matchCode;
 351
 352                                 if (ip == limit) {
 353                                         unsigned const int more = LZ4_count(ip,
 354                                                 (const BYTE *)source,
 355                                                 matchlimit);
 356
 357                                         matchCode += more;
 358                                         ip += more;
 359                                 }
 360                         } else {
 361                                 matchCode = LZ4_count(ip + MINMATCH,
 362                                         match + MINMATCH, matchlimit);
 363                                 ip += MINMATCH + matchCode;
 364                         }
 365
 366                         if (outputLimited &&
 367                                 /* Check output buffer overflow */
 368                                 (unlikely(op +
 369                                         (1 + LASTLITERALS) +
 370                                         (matchCode >> 8) > olimit)))
 371                                 return 0;
 372
 373                         if (matchCode >= ML_MASK) {
 374                                 *token += ML_MASK;
 375                                 matchCode -= ML_MASK;
 376                                 LZ4_write32(op, 0xFFFFFFFF);
 377
 378                                 while (matchCode >= 4 * 255) {
 379                                         op += 4;
 380                                         LZ4_write32(op, 0xFFFFFFFF);
 381                                         matchCode -= 4 * 255;
 382                                 }
 383
 384                                 op += matchCode / 255;
 385                                 *op++ = (BYTE)(matchCode % 255);
 386                         } else
 387                                 *token += (BYTE)(matchCode);
 388                 }
 389
 390                 anchor = ip;
 391
 392                 /* Test end of chunk */
 393                 if (ip > mflimit)
 394                         break;
 395
 396                 /* Fill table */
 397                 LZ4_putPosition(ip - 2, dictPtr->hashTable, tableType, base);
 398
 399                 /* Test next position */
 400                 match = LZ4_getPosition(ip, dictPtr->hashTable,
 401                         tableType, base);
 402
 403                 if (dict == usingExtDict) {
 404                         if (match < (const BYTE *)source) {
 405                                 refDelta = dictDelta;
 406                                 lowLimit = dictionary;
 407                         } else {
 408                                 refDelta = 0;
 409                                 lowLimit = (const BYTE *)source;
 410                         }
 411                 }
 412
 413                 LZ4_putPosition(ip, dictPtr->hashTable, tableType, base);
 414
 415                 if (((dictIssue == dictSmall) ? (match >= lowRefLimit) : 1)
 416                         && (match + MAX_DISTANCE >= ip)
 417                         && (LZ4_read32(match + refDelta) == LZ4_read32(ip))) {
 418                         token = op++;
 419                         *token = 0;
 420                         goto _next_match;
 421                 }
 422
 423                 /* Prepare next loop */
 424                 forwardH = LZ4_hashPosition(++ip, tableType);
 425         }
 426
 427 _last_literals:
 428         /* Encode Last Literals */
 429         {
 430                 size_t const lastRun = (size_t)(iend - anchor);
 431
 432                 if ((outputLimited) &&
 433                         /* Check output buffer overflow */
 434                         ((op - (BYTE *)dest) + lastRun + 1 +
 435                         ((lastRun + 255 - RUN_MASK) / 255) > (U32)maxOutputSize))
 436                         return 0;
 437
 438                 if (lastRun >= RUN_MASK) {
 439                         size_t accumulator = lastRun - RUN_MASK;
 440                         *op++ = RUN_MASK << ML_BITS;
 441                         for (; accumulator >= 255; accumulator -= 255)
 442                                 *op++ = 255;
 443                         *op++ = (BYTE) accumulator;
 444                 } else {
 445                         *op++ = (BYTE)(lastRun << ML_BITS);
 446                 }
 447
 448                 memcpy(op, anchor, lastRun);
 449
 450                 op += lastRun;
 451         }
 452
 453         /* End */
 454         return (int) (((char *)op) - dest);
 455 }
 456
 457 static int LZ4_compress_fast_extState(
 458         void *state,
 459         const char *source,
 460         char *dest,
 461         int inputSize,
 462         int maxOutputSize,
 463         int acceleration)
 464 {
 465         LZ4_stream_t_internal *ctx = &((LZ4_stream_t *)state)->internal_donotuse;
 466 #if LZ4_ARCH64
 467         const tableType_t tableType = byU32;
 468 #else
 469         const tableType_t tableType = byPtr;
 470 #endif
 471
 472         LZ4_resetStream((LZ4_stream_t *)state);
 473
 474         if (acceleration < 1)
 475                 acceleration = LZ4_ACCELERATION_DEFAULT;
 476
 477         if (maxOutputSize >= LZ4_COMPRESSBOUND(inputSize)) {
 478                 if (inputSize < LZ4_64Klimit)
 479                         return LZ4_compress_generic(ctx, source,
 480                                 dest, inputSize, 0,
 481                                 noLimit, byU16, noDict,
 482                                 noDictIssue, acceleration);
 483                 else
 484                         return LZ4_compress_generic(ctx, source,
 485                                 dest, inputSize, 0,
 486                                 noLimit, tableType, noDict,
 487                                 noDictIssue, acceleration);
 488         } else {
 489                 if (inputSize < LZ4_64Klimit)
 490                         return LZ4_compress_generic(ctx, source,
 491                                 dest, inputSize,
 492                                 maxOutputSize, limitedOutput, byU16, noDict,
 493                                 noDictIssue, acceleration);
 494                 else
 495                         return LZ4_compress_generic(ctx, source,
 496                                 dest, inputSize,
 497                                 maxOutputSize, limitedOutput, tableType, noDict,
 498                                 noDictIssue, acceleration);
 499         }
 500 }
 501
 502 int LZ4_compress_fast(const char *source, char *dest, int inputSize,
 503         int maxOutputSize, int acceleration, void *wrkmem)
 504 {
 505         return LZ4_compress_fast_extState(wrkmem, source, dest, inputSize,
 506                 maxOutputSize, acceleration);
 507 }
 508
 509 int LZ4_compress_default(const char *source, char *dest, int inputSize,
 510         int maxOutputSize, void *wrkmem)
 511 {
 512         return LZ4_compress_fast(source, dest, inputSize,
 513                 maxOutputSize, LZ4_ACCELERATION_DEFAULT, wrkmem);
 514 }
 515
 516 /*-******************************
 517  *      *_destSize() variant
 518  ********************************/
 519 static int LZ4_compress_destSize_generic(
 520         LZ4_stream_t_internal * const ctx,
 521         const char * const src,
 522         char * const dst,
 523         int * const srcSizePtr,
 524         const int targetDstSize,
 525         const tableType_t tableType)
 526 {
 527         const BYTE *ip = (const BYTE *) src;
 528         const BYTE *base = (const BYTE *) src;
 529         const BYTE *lowLimit = (const BYTE *) src;
 530         const BYTE *anchor = ip;
 531         const BYTE * const iend = ip + *srcSizePtr;
 532         const BYTE * const mflimit = iend - MFLIMIT;
 533         const BYTE * const matchlimit = iend - LASTLITERALS;
 534
 535         BYTE *op = (BYTE *) dst;
 536         BYTE * const oend = op + targetDstSize;
 537         BYTE * const oMaxLit = op + targetDstSize - 2 /* offset */
 538                 - 8 /* because 8 + MINMATCH == MFLIMIT */ - 1 /* token */;
 539         BYTE * const oMaxMatch = op + targetDstSize
 540                 - (LASTLITERALS + 1 /* token */);
 541         BYTE * const oMaxSeq = oMaxLit - 1 /* token */;
 542
 543         U32 forwardH;
 544
 545         /* Init conditions */
 546         /* Impossible to store anything */
 547         if (targetDstSize < 1)
 548                 return 0;
 549         /* Unsupported input size, too large (or negative) */
 550         if ((U32)*srcSizePtr > (U32)LZ4_MAX_INPUT_SIZE)
 551                 return 0;
 552         /* Size too large (not within 64K limit) */
 553         if ((tableType == byU16) && (*srcSizePtr >= LZ4_64Klimit))
 554                 return 0;
 555         /* Input too small, no compression (all literals) */
 556         if (*srcSizePtr < LZ4_minLength)
 557                 goto _last_literals;
 558
 559         /* First Byte */
 560         *srcSizePtr = 0;
 561         LZ4_putPosition(ip, ctx->hashTable, tableType, base);
 562         ip++; forwardH = LZ4_hashPosition(ip, tableType);
 563
 564         /* Main Loop */
 565         for ( ; ; ) {
 566                 const BYTE *match;
 567                 BYTE *token;
 568
 569                 /* Find a match */
 570                 {
 571                         const BYTE *forwardIp = ip;
 572                         unsigned int step = 1;
 573                         unsigned int searchMatchNb = 1 << LZ4_SKIPTRIGGER;
 574
 575                         do {
 576                                 U32 h = forwardH;
 577
 578                                 ip = forwardIp;
 579                                 forwardIp += step;
 580                                 step = (searchMatchNb++ >> LZ4_SKIPTRIGGER);
 581
 582                                 if (unlikely(forwardIp > mflimit))
 583                                         goto _last_literals;
 584
 585                                 match = LZ4_getPositionOnHash(h, ctx->hashTable,
 586                                         tableType, base);
 587                                 forwardH = LZ4_hashPosition(forwardIp,
 588                                         tableType);
 589                                 LZ4_putPositionOnHash(ip, h,
 590                                         ctx->hashTable, tableType,
 591                                         base);
 592
 593                         } while (((tableType == byU16)
 594                                 ? 0
 595                                 : (match + MAX_DISTANCE < ip))
 596                                 || (LZ4_read32(match) != LZ4_read32(ip)));
 597                 }
 598
 599                 /* Catch up */
 600                 while ((ip > anchor)
 601                         && (match > lowLimit)
 602                         && (unlikely(ip[-1] == match[-1]))) {
 603                         ip--;
 604                         match--;
 605                 }
 606
 607                 /* Encode Literal length */
 608                 {
 609                         unsigned int litLength = (unsigned int)(ip - anchor);
 610
 611                         token = op++;
 612                         if (op + ((litLength + 240) / 255)
 613                                 + litLength > oMaxLit) {
 614                                 /* Not enough space for a last match */
 615                                 op--;
 616                                 goto _last_literals;
 617                         }
 618                         if (litLength >= RUN_MASK) {
 619                                 unsigned int len = litLength - RUN_MASK;
 620                                 *token = (RUN_MASK<<ML_BITS);
 621                                 for (; len >= 255; len -= 255)
 622                                         *op++ = 255;
 623                                 *op++ = (BYTE)len;
 624                         } else
 625                                 *token = (BYTE)(litLength << ML_BITS);
 626
 627                         /* Copy Literals */
 628                         LZ4_wildCopy(op, anchor, op + litLength);
 629                         op += litLength;
 630                 }
 631
 632 _next_match:
 633                 /* Encode Offset */
 634                 LZ4_writeLE16(op, (U16)(ip - match)); op += 2;
 635
 636                 /* Encode MatchLength */
 637                 {
 638                         size_t matchLength = LZ4_count(ip + MINMATCH,
 639                         match + MINMATCH, matchlimit);
 640
 641                         if (op + ((matchLength + 240)/255) > oMaxMatch) {
 642                                 /* Match description too long : reduce it */
 643                                 matchLength = (15 - 1) + (oMaxMatch - op) * 255;
 644                         }
 645                         ip += MINMATCH + matchLength;
 646
 647                         if (matchLength >= ML_MASK) {
 648                                 *token += ML_MASK;
 649                                 matchLength -= ML_MASK;
 650                                 while (matchLength >= 255) {
 651                                         matchLength -= 255;
 652                                         *op++ = 255;
 653                                 }
 654                                 *op++ = (BYTE)matchLength;
 655                         } else
 656                                 *token += (BYTE)(matchLength);
 657                 }
 658
 659                 anchor = ip;
 660
 661                 /* Test end of block */
 662                 if (ip > mflimit)
 663                         break;
 664                 if (op > oMaxSeq)
 665                         break;
 666
 667                 /* Fill table */
 668                 LZ4_putPosition(ip - 2, ctx->hashTable, tableType, base);
 669
 670                 /* Test next position */
 671                 match = LZ4_getPosition(ip, ctx->hashTable, tableType, base);
 672                 LZ4_putPosition(ip, ctx->hashTable, tableType, base);
 673
 674                 if ((match + MAX_DISTANCE >= ip)
 675                         && (LZ4_read32(match) == LZ4_read32(ip))) {
 676                         token = op++; *token = 0;
 677                         goto _next_match;
 678                 }
 679
 680                 /* Prepare next loop */
 681                 forwardH = LZ4_hashPosition(++ip, tableType);
 682         }
 683
 684 _last_literals:
 685         /* Encode Last Literals */
 686         {
 687                 size_t lastRunSize = (size_t)(iend - anchor);
 688
 689                 if (op + 1 /* token */
 690                         + ((lastRunSize + 240) / 255) /* litLength */
 691                         + lastRunSize /* literals */ > oend) {
 692                         /* adapt lastRunSize to fill 'dst' */
 693                         lastRunSize     = (oend - op) - 1;
 694                         lastRunSize -= (lastRunSize + 240) / 255;
 695                 }
 696                 ip = anchor + lastRunSize;
 697
 698                 if (lastRunSize >= RUN_MASK) {
 699                         size_t accumulator = lastRunSize - RUN_MASK;
 700
 701                         *op++ = RUN_MASK << ML_BITS;
 702                         for (; accumulator >= 255; accumulator -= 255)
 703                                 *op++ = 255;
 704                         *op++ = (BYTE) accumulator;
 705                 } else {
 706                         *op++ = (BYTE)(lastRunSize<<ML_BITS);
 707                 }
 708                 memcpy(op, anchor, lastRunSize);
 709                 op += lastRunSize;
 710         }
 711
 712         /* End */
 713         *srcSizePtr = (int) (((const char *)ip) - src);
 714         return (int) (((char *)op) - dst);
 715 }
 716
 717 static int LZ4_compress_destSize_extState(
 718         LZ4_stream_t *state,
 719         const char *src,
 720         char *dst,
 721         int *srcSizePtr,
 722         int targetDstSize)
 723 {
 724 #if LZ4_ARCH64
 725         const tableType_t tableType = byU32;
 726 #else
 727         const tableType_t tableType = byPtr;
 728 #endif
 729
 730         LZ4_resetStream(state);
 731
 732         if (targetDstSize >= LZ4_COMPRESSBOUND(*srcSizePtr)) {
 733                 /* compression success is guaranteed */
 734                 return LZ4_compress_fast_extState(
 735                         state, src, dst, *srcSizePtr,
 736                         targetDstSize, 1);
 737         } else {
 738                 if (*srcSizePtr < LZ4_64Klimit)
 739                         return LZ4_compress_destSize_generic(
 740                                 &state->internal_donotuse,
 741                                 src, dst, srcSizePtr,
 742                                 targetDstSize, byU16);
 743                 else
 744                         return LZ4_compress_destSize_generic(
 745                                 &state->internal_donotuse,
 746                                 src, dst, srcSizePtr,
 747                                 targetDstSize, tableType);
 748         }
 749 }
 750
 751
 752 int LZ4_compress_destSize(
 753         const char *src,
 754         char *dst,
 755         int *srcSizePtr,
 756         int targetDstSize,
 757         void *wrkmem)
 758 {
 759         return LZ4_compress_destSize_extState(wrkmem, src, dst, srcSizePtr,
 760                 targetDstSize);
 761 }
 762
 763 /*-******************************
 764  *      Streaming functions
 765  ********************************/
 766 void LZ4_resetStream(LZ4_stream_t *LZ4_stream)
 767 {
 768         memset(LZ4_stream, 0, sizeof(LZ4_stream_t));
 769 }
 770
 771 int LZ4_loadDict(LZ4_stream_t *LZ4_dict,
 772         const char *dictionary, int dictSize)
 773 {
 774         LZ4_stream_t_internal *dict = &LZ4_dict->internal_donotuse;
 775         const BYTE *p = (const BYTE *)dictionary;
 776         const BYTE * const dictEnd = p + dictSize;
 777         const BYTE *base;
 778
 779         if ((dict->initCheck)
 780                 || (dict->currentOffset > 1 * GB)) {
 781                 /* Uninitialized structure, or reuse overflow */
 782                 LZ4_resetStream(LZ4_dict);
 783         }
 784
 785         if (dictSize < (int)HASH_UNIT) {
 786                 dict->dictionary = NULL;
 787                 dict->dictSize = 0;
 788                 return 0;
 789         }
 790
 791         if ((dictEnd - p) > 64 * KB)
 792                 p = dictEnd - 64 * KB;
 793         dict->currentOffset += 64 * KB;
 794         base = p - dict->currentOffset;
 795         dict->dictionary = p;
 796         dict->dictSize = (U32)(dictEnd - p);
 797         dict->currentOffset += dict->dictSize;
 798
 799         while (p <= dictEnd - HASH_UNIT) {
 800                 LZ4_putPosition(p, dict->hashTable, byU32, base);
 801                 p += 3;
 802         }
 803
 804         return dict->dictSize;
 805 }
 806
 807 static void LZ4_renormDictT(LZ4_stream_t_internal *LZ4_dict,
 808         const BYTE *src)
 809 {
 810         if ((LZ4_dict->currentOffset > 0x80000000) ||
 811                 ((uptrval)LZ4_dict->currentOffset > (uptrval)src)) {
 812                 /* address space overflow */
 813                 /* rescale hash table */
 814                 U32 const delta = LZ4_dict->currentOffset - 64 * KB;
 815                 const BYTE *dictEnd = LZ4_dict->dictionary + LZ4_dict->dictSize;
 816                 int i;
 817
 818                 for (i = 0; i < LZ4_HASH_SIZE_U32; i++) {
 819                         if (LZ4_dict->hashTable[i] < delta)
 820                                 LZ4_dict->hashTable[i] = 0;
 821                         else
 822                                 LZ4_dict->hashTable[i] -= delta;
 823                 }
 824                 LZ4_dict->currentOffset = 64 * KB;
 825                 if (LZ4_dict->dictSize > 64 * KB)
 826                         LZ4_dict->dictSize = 64 * KB;
 827                 LZ4_dict->dictionary = dictEnd - LZ4_dict->dictSize;
 828         }
 829 }
 830
 831 int LZ4_saveDict(LZ4_stream_t *LZ4_dict, char *safeBuffer, int dictSize)
 832 {
 833         LZ4_stream_t_internal * const dict = &LZ4_dict->internal_donotuse;
 834         const BYTE * const previousDictEnd = dict->dictionary + dict->dictSize;
 835
 836         if ((U32)dictSize > 64 * KB) {
 837                 /* useless to define a dictionary > 64 * KB */
 838                 dictSize = 64 * KB;
 839         }
 840         if ((U32)dictSize > dict->dictSize)
 841                 dictSize = dict->dictSize;
 842
 843         memmove(safeBuffer, previousDictEnd - dictSize, dictSize);
 844
 845         dict->dictionary = (const BYTE *)safeBuffer;
 846         dict->dictSize = (U32)dictSize;
 847
 848         return dictSize;
 849 }
 850
 851 int LZ4_compress_fast_continue(LZ4_stream_t *LZ4_stream, const char *source,
 852         char *dest, int inputSize, int maxOutputSize, int acceleration)
 853 {
 854         LZ4_stream_t_internal *streamPtr = &LZ4_stream->internal_donotuse;
 855         const BYTE * const dictEnd = streamPtr->dictionary
 856                 + streamPtr->dictSize;
 857
 858         const BYTE *smallest = (const BYTE *) source;
 859
 860         if (streamPtr->initCheck) {
 861                 /* Uninitialized structure detected */
 862                 return 0;
 863         }
 864
 865         if ((streamPtr->dictSize > 0) && (smallest > dictEnd))
 866                 smallest = dictEnd;
 867
 868         LZ4_renormDictT(streamPtr, smallest);
 869
 870         if (acceleration < 1)
 871                 acceleration = LZ4_ACCELERATION_DEFAULT;
 872
 873         /* Check overlapping input/dictionary space */
 874         {
 875                 const BYTE *sourceEnd = (const BYTE *) source + inputSize;
 876
 877                 if ((sourceEnd > streamPtr->dictionary)
 878                         && (sourceEnd < dictEnd)) {
 879                         streamPtr->dictSize = (U32)(dictEnd - sourceEnd);
 880                         if (streamPtr->dictSize > 64 * KB)
 881                                 streamPtr->dictSize = 64 * KB;
 882                         if (streamPtr->dictSize < 4)
 883                                 streamPtr->dictSize = 0;
 884                         streamPtr->dictionary = dictEnd - streamPtr->dictSize;
 885                 }
 886         }
 887
 888         /* prefix mode : source data follows dictionary */
 889         if (dictEnd == (const BYTE *)source) {
 890                 int result;
 891
 892                 if ((streamPtr->dictSize < 64 * KB) &&
 893                         (streamPtr->dictSize < streamPtr->currentOffset)) {
 894                         result = LZ4_compress_generic(
 895                                 streamPtr, source, dest, inputSize,
 896                                 maxOutputSize, limitedOutput, byU32,
 897                                 withPrefix64k, dictSmall, acceleration);
 898                 } else {
 899                         result = LZ4_compress_generic(
 900                                 streamPtr, source, dest, inputSize,
 901                                 maxOutputSize, limitedOutput, byU32,
 902                                 withPrefix64k, noDictIssue, acceleration);
 903                 }
 904                 streamPtr->dictSize += (U32)inputSize;
 905                 streamPtr->currentOffset += (U32)inputSize;
 906                 return result;
 907         }
 908
 909         /* external dictionary mode */
 910         {
 911                 int result;
 912
 913                 if ((streamPtr->dictSize < 64 * KB) &&
 914                         (streamPtr->dictSize < streamPtr->currentOffset)) {
 915                         result = LZ4_compress_generic(
 916                                 streamPtr, source, dest, inputSize,
 917                                 maxOutputSize, limitedOutput, byU32,
 918                                 usingExtDict, dictSmall, acceleration);
 919                 } else {
 920                         result = LZ4_compress_generic(
 921                                 streamPtr, source, dest, inputSize,
 922                                 maxOutputSize, limitedOutput, byU32,
 923                                 usingExtDict, noDictIssue, acceleration);
 924                 }
 925                 streamPtr->dictionary = (const BYTE *)source;
 926                 streamPtr->dictSize = (U32)inputSize;
 927                 streamPtr->currentOffset += (U32)inputSize;
 928                 return result;
 929         }
 930 }