lib/lz4/lz4_compress.c

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This source file includes following definitions.
LZ4_hash4
LZ4_hash5
LZ4_hashPosition
LZ4_putPositionOnHash
LZ4_putPosition
LZ4_getPositionOnHash
LZ4_getPosition
LZ4_compress_generic
LZ4_compress_fast_extState
LZ4_compress_fast
LZ4_compress_default
LZ4_compress_destSize_generic
LZ4_compress_destSize_extState
LZ4_compress_destSize
LZ4_resetStream
LZ4_loadDict
LZ4_renormDictT
LZ4_saveDict
LZ4_compress_fast_continue
   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/module.h>
  39 #include <linux/kernel.h>
  40 #include <asm/unaligned.h>
  41 
  42 static const int LZ4_minLength = (MFLIMIT + 1);
  43 static const int LZ4_64Klimit = ((64 * KB) + (MFLIMIT - 1));
  44 
  45 /*-******************************
  46  *      Compression functions
  47  ********************************/
  48 static FORCE_INLINE U32 LZ4_hash4(
  49         U32 sequence,
  50         tableType_t const tableType)
  51 {
  52         if (tableType == byU16)
  53                 return ((sequence * 2654435761U)
  54                         >> ((MINMATCH * 8) - (LZ4_HASHLOG + 1)));
  55         else
  56                 return ((sequence * 2654435761U)
  57                         >> ((MINMATCH * 8) - LZ4_HASHLOG));
  58 }
  59 
  60 static FORCE_INLINE U32 LZ4_hash5(
  61         U64 sequence,
  62         tableType_t const tableType)
  63 {
  64         const U32 hashLog = (tableType == byU16)
  65                 ? LZ4_HASHLOG + 1
  66                 : LZ4_HASHLOG;
  67 
  68 #if LZ4_LITTLE_ENDIAN
  69         static const U64 prime5bytes = 889523592379ULL;
  70 
  71         return (U32)(((sequence << 24) * prime5bytes) >> (64 - hashLog));
  72 #else
  73         static const U64 prime8bytes = 11400714785074694791ULL;
  74 
  75         return (U32)(((sequence >> 24) * prime8bytes) >> (64 - hashLog));
  76 #endif
  77 }
  78 
  79 static FORCE_INLINE U32 LZ4_hashPosition(
  80         const void *p,
  81         tableType_t const tableType)
  82 {
  83 #if LZ4_ARCH64
  84         if (tableType == byU32)
  85                 return LZ4_hash5(LZ4_read_ARCH(p), tableType);
  86 #endif
  87 
  88         return LZ4_hash4(LZ4_read32(p), tableType);
  89 }
  90 
  91 static void LZ4_putPositionOnHash(
  92         const BYTE *p,
  93         U32 h,
  94         void *tableBase,
  95         tableType_t const tableType,
  96         const BYTE *srcBase)
  97 {
  98         switch (tableType) {
  99         case byPtr:
 100         {
 101                 const BYTE **hashTable = (const BYTE **)tableBase;
 102 
 103                 hashTable[h] = p;
 104                 return;
 105         }
 106         case byU32:
 107         {
 108                 U32 *hashTable = (U32 *) tableBase;
 109 
 110                 hashTable[h] = (U32)(p - srcBase);
 111                 return;
 112         }
 113         case byU16:
 114         {
 115                 U16 *hashTable = (U16 *) tableBase;
 116 
 117                 hashTable[h] = (U16)(p - srcBase);
 118                 return;
 119         }
 120         }
 121 }
 122 
 123 static FORCE_INLINE void LZ4_putPosition(
 124         const BYTE *p,
 125         void *tableBase,
 126         tableType_t tableType,
 127         const BYTE *srcBase)
 128 {
 129         U32 const h = LZ4_hashPosition(p, tableType);
 130 
 131         LZ4_putPositionOnHash(p, h, tableBase, tableType, srcBase);
 132 }
 133 
 134 static const BYTE *LZ4_getPositionOnHash(
 135         U32 h,
 136         void *tableBase,
 137         tableType_t tableType,
 138         const BYTE *srcBase)
 139 {
 140         if (tableType == byPtr) {
 141                 const BYTE **hashTable = (const BYTE **) tableBase;
 142 
 143                 return hashTable[h];
 144         }
 145 
 146         if (tableType == byU32) {
 147                 const U32 * const hashTable = (U32 *) tableBase;
 148 
 149                 return hashTable[h] + srcBase;
 150         }
 151 
 152         {
 153                 /* default, to ensure a return */
 154                 const U16 * const hashTable = (U16 *) tableBase;
 155 
 156                 return hashTable[h] + srcBase;
 157         }
 158 }
 159 
 160 static FORCE_INLINE const BYTE *LZ4_getPosition(
 161         const BYTE *p,
 162         void *tableBase,
 163         tableType_t tableType,
 164         const BYTE *srcBase)
 165 {
 166         U32 const h = LZ4_hashPosition(p, tableType);
 167 
 168         return LZ4_getPositionOnHash(h, tableBase, tableType, srcBase);
 169 }
 170 
 171 
 172 /*
 173  * LZ4_compress_generic() :
 174  * inlined, to ensure branches are decided at compilation time
 175  */
 176 static FORCE_INLINE int LZ4_compress_generic(
 177         LZ4_stream_t_internal * const dictPtr,
 178         const char * const source,
 179         char * const dest,
 180         const int inputSize,
 181         const int maxOutputSize,
 182         const limitedOutput_directive outputLimited,
 183         const tableType_t tableType,
 184         const dict_directive dict,
 185         const dictIssue_directive dictIssue,
 186         const U32 acceleration)
 187 {
 188         const BYTE *ip = (const BYTE *) source;
 189         const BYTE *base;
 190         const BYTE *lowLimit;
 191         const BYTE * const lowRefLimit = ip - dictPtr->dictSize;
 192         const BYTE * const dictionary = dictPtr->dictionary;
 193         const BYTE * const dictEnd = dictionary + dictPtr->dictSize;
 194         const size_t dictDelta = dictEnd - (const BYTE *)source;
 195         const BYTE *anchor = (const BYTE *) source;
 196         const BYTE * const iend = ip + inputSize;
 197         const BYTE * const mflimit = iend - MFLIMIT;
 198         const BYTE * const matchlimit = iend - LASTLITERALS;
 199 
 200         BYTE *op = (BYTE *) dest;
 201         BYTE * const olimit = op + maxOutputSize;
 202 
 203         U32 forwardH;
 204         size_t refDelta = 0;
 205 
 206         /* Init conditions */
 207         if ((U32)inputSize > (U32)LZ4_MAX_INPUT_SIZE) {
 208                 /* Unsupported inputSize, too large (or negative) */
 209                 return 0;
 210         }
 211 
 212         switch (dict) {
 213         case noDict:
 214         default:
 215                 base = (const BYTE *)source;
 216                 lowLimit = (const BYTE *)source;
 217                 break;
 218         case withPrefix64k:
 219                 base = (const BYTE *)source - dictPtr->currentOffset;
 220                 lowLimit = (const BYTE *)source - dictPtr->dictSize;
 221                 break;
 222         case usingExtDict:
 223                 base = (const BYTE *)source - dictPtr->currentOffset;
 224                 lowLimit = (const BYTE *)source;
 225                 break;
 226         }
 227 
 228         if ((tableType == byU16)
 229                 && (inputSize >= LZ4_64Klimit)) {
 230                 /* Size too large (not within 64K limit) */
 231                 return 0;
 232         }
 233 
 234         if (inputSize < LZ4_minLength) {
 235                 /* Input too small, no compression (all literals) */
 236                 goto _last_literals;
 237         }
 238 
 239         /* First Byte */
 240         LZ4_putPosition(ip, dictPtr->hashTable, tableType, base);
 241         ip++;
 242         forwardH = LZ4_hashPosition(ip, tableType);
 243 
 244         /* Main Loop */
 245         for ( ; ; ) {
 246                 const BYTE *match;
 247                 BYTE *token;
 248 
 249                 /* Find a match */
 250                 {
 251                         const BYTE *forwardIp = ip;
 252                         unsigned int step = 1;
 253                         unsigned int searchMatchNb = acceleration << LZ4_SKIPTRIGGER;
 254 
 255                         do {
 256                                 U32 const h = forwardH;
 257 
 258                                 ip = forwardIp;
 259                                 forwardIp += step;
 260                                 step = (searchMatchNb++ >> LZ4_SKIPTRIGGER);
 261 
 262                                 if (unlikely(forwardIp > mflimit))
 263                                         goto _last_literals;
 264 
 265                                 match = LZ4_getPositionOnHash(h,
 266                                         dictPtr->hashTable,
 267                                         tableType, base);
 268 
 269                                 if (dict == usingExtDict) {
 270                                         if (match < (const BYTE *)source) {
 271                                                 refDelta = dictDelta;
 272                                                 lowLimit = dictionary;
 273                                         } else {
 274                                                 refDelta = 0;
 275                                                 lowLimit = (const BYTE *)source;
 276                                 }        }
 277 
 278                                 forwardH = LZ4_hashPosition(forwardIp,
 279                                         tableType);
 280 
 281                                 LZ4_putPositionOnHash(ip, h, dictPtr->hashTable,
 282                                         tableType, base);
 283                         } while (((dictIssue == dictSmall)
 284                                         ? (match < lowRefLimit)
 285                                         : 0)
 286                                 || ((tableType == byU16)
 287                                         ? 0
 288                                         : (match + MAX_DISTANCE < ip))
 289                                 || (LZ4_read32(match + refDelta)
 290                                         != LZ4_read32(ip)));
 291                 }
 292 
 293                 /* Catch up */
 294                 while (((ip > anchor) & (match + refDelta > lowLimit))
 295                                 && (unlikely(ip[-1] == match[refDelta - 1]))) {
 296                         ip--;
 297                         match--;
 298                 }
 299 
 300                 /* Encode Literals */
 301                 {
 302                         unsigned const int litLength = (unsigned int)(ip - anchor);
 303 
 304                         token = op++;
 305 
 306                         if ((outputLimited) &&
 307                                 /* Check output buffer overflow */
 308                                 (unlikely(op + litLength +
 309                                         (2 + 1 + LASTLITERALS) +
 310                                         (litLength / 255) > olimit)))
 311                                 return 0;
 312 
 313                         if (litLength >= RUN_MASK) {
 314                                 int len = (int)litLength - RUN_MASK;
 315 
 316                                 *token = (RUN_MASK << ML_BITS);
 317 
 318                                 for (; len >= 255; len -= 255)
 319                                         *op++ = 255;
 320                                 *op++ = (BYTE)len;
 321                         } else
 322                                 *token = (BYTE)(litLength << ML_BITS);
 323 
 324                         /* Copy Literals */
 325                         LZ4_wildCopy(op, anchor, op + litLength);
 326                         op += litLength;
 327                 }
 328 
 329 _next_match:
 330                 /* Encode Offset */
 331                 LZ4_writeLE16(op, (U16)(ip - match));
 332                 op += 2;
 333 
 334                 /* Encode MatchLength */
 335                 {
 336                         unsigned int matchCode;
 337 
 338                         if ((dict == usingExtDict)
 339                                 && (lowLimit == dictionary)) {
 340                                 const BYTE *limit;
 341 
 342                                 match += refDelta;
 343                                 limit = ip + (dictEnd - match);
 344 
 345                                 if (limit > matchlimit)
 346                                         limit = matchlimit;
 347 
 348                                 matchCode = LZ4_count(ip + MINMATCH,
 349                                         match + MINMATCH, limit);
 350 
 351                                 ip += MINMATCH + matchCode;
 352 
 353                                 if (ip == limit) {
 354                                         unsigned const int more = LZ4_count(ip,
 355                                                 (const BYTE *)source,
 356                                                 matchlimit);
 357 
 358                                         matchCode += more;
 359                                         ip += more;
 360                                 }
 361                         } else {
 362                                 matchCode = LZ4_count(ip + MINMATCH,
 363                                         match + MINMATCH, matchlimit);
 364                                 ip += MINMATCH + matchCode;
 365                         }
 366 
 367                         if (outputLimited &&
 368                                 /* Check output buffer overflow */
 369                                 (unlikely(op +
 370                                         (1 + LASTLITERALS) +
 371                                         (matchCode >> 8) > olimit)))
 372                                 return 0;
 373 
 374                         if (matchCode >= ML_MASK) {
 375                                 *token += ML_MASK;
 376                                 matchCode -= ML_MASK;
 377                                 LZ4_write32(op, 0xFFFFFFFF);
 378 
 379                                 while (matchCode >= 4 * 255) {
 380                                         op += 4;
 381                                         LZ4_write32(op, 0xFFFFFFFF);
 382                                         matchCode -= 4 * 255;
 383                                 }
 384 
 385                                 op += matchCode / 255;
 386                                 *op++ = (BYTE)(matchCode % 255);
 387                         } else
 388                                 *token += (BYTE)(matchCode);
 389                 }
 390 
 391                 anchor = ip;
 392 
 393                 /* Test end of chunk */
 394                 if (ip > mflimit)
 395                         break;
 396 
 397                 /* Fill table */
 398                 LZ4_putPosition(ip - 2, dictPtr->hashTable, tableType, base);
 399 
 400                 /* Test next position */
 401                 match = LZ4_getPosition(ip, dictPtr->hashTable,
 402                         tableType, base);
 403 
 404                 if (dict == usingExtDict) {
 405                         if (match < (const BYTE *)source) {
 406                                 refDelta = dictDelta;
 407                                 lowLimit = dictionary;
 408                         } else {
 409                                 refDelta = 0;
 410                                 lowLimit = (const BYTE *)source;
 411                         }
 412                 }
 413 
 414                 LZ4_putPosition(ip, dictPtr->hashTable, tableType, base);
 415 
 416                 if (((dictIssue == dictSmall) ? (match >= lowRefLimit) : 1)
 417                         && (match + MAX_DISTANCE >= ip)
 418                         && (LZ4_read32(match + refDelta) == LZ4_read32(ip))) {
 419                         token = op++;
 420                         *token = 0;
 421                         goto _next_match;
 422                 }
 423 
 424                 /* Prepare next loop */
 425                 forwardH = LZ4_hashPosition(++ip, tableType);
 426         }
 427 
 428 _last_literals:
 429         /* Encode Last Literals */
 430         {
 431                 size_t const lastRun = (size_t)(iend - anchor);
 432 
 433                 if ((outputLimited) &&
 434                         /* Check output buffer overflow */
 435                         ((op - (BYTE *)dest) + lastRun + 1 +
 436                         ((lastRun + 255 - RUN_MASK) / 255) > (U32)maxOutputSize))
 437                         return 0;
 438 
 439                 if (lastRun >= RUN_MASK) {
 440                         size_t accumulator = lastRun - RUN_MASK;
 441                         *op++ = RUN_MASK << ML_BITS;
 442                         for (; accumulator >= 255; accumulator -= 255)
 443                                 *op++ = 255;
 444                         *op++ = (BYTE) accumulator;
 445                 } else {
 446                         *op++ = (BYTE)(lastRun << ML_BITS);
 447                 }
 448 
 449                 memcpy(op, anchor, lastRun);
 450 
 451                 op += lastRun;
 452         }
 453 
 454         /* End */
 455         return (int) (((char *)op) - dest);
 456 }
 457 
 458 static int LZ4_compress_fast_extState(
 459         void *state,
 460         const char *source,
 461         char *dest,
 462         int inputSize,
 463         int maxOutputSize,
 464         int acceleration)
 465 {
 466         LZ4_stream_t_internal *ctx = &((LZ4_stream_t *)state)->internal_donotuse;
 467 #if LZ4_ARCH64
 468         const tableType_t tableType = byU32;
 469 #else
 470         const tableType_t tableType = byPtr;
 471 #endif
 472 
 473         LZ4_resetStream((LZ4_stream_t *)state);
 474 
 475         if (acceleration < 1)
 476                 acceleration = LZ4_ACCELERATION_DEFAULT;
 477 
 478         if (maxOutputSize >= LZ4_COMPRESSBOUND(inputSize)) {
 479                 if (inputSize < LZ4_64Klimit)
 480                         return LZ4_compress_generic(ctx, source,
 481                                 dest, inputSize, 0,
 482                                 noLimit, byU16, noDict,
 483                                 noDictIssue, acceleration);
 484                 else
 485                         return LZ4_compress_generic(ctx, source,
 486                                 dest, inputSize, 0,
 487                                 noLimit, tableType, noDict,
 488                                 noDictIssue, acceleration);
 489         } else {
 490                 if (inputSize < LZ4_64Klimit)
 491                         return LZ4_compress_generic(ctx, source,
 492                                 dest, inputSize,
 493                                 maxOutputSize, limitedOutput, byU16, noDict,
 494                                 noDictIssue, acceleration);
 495                 else
 496                         return LZ4_compress_generic(ctx, source,
 497                                 dest, inputSize,
 498                                 maxOutputSize, limitedOutput, tableType, noDict,
 499                                 noDictIssue, acceleration);
 500         }
 501 }
 502 
 503 int LZ4_compress_fast(const char *source, char *dest, int inputSize,
 504         int maxOutputSize, int acceleration, void *wrkmem)
 505 {
 506         return LZ4_compress_fast_extState(wrkmem, source, dest, inputSize,
 507                 maxOutputSize, acceleration);
 508 }
 509 EXPORT_SYMBOL(LZ4_compress_fast);
 510 
 511 int LZ4_compress_default(const char *source, char *dest, int inputSize,
 512         int maxOutputSize, void *wrkmem)
 513 {
 514         return LZ4_compress_fast(source, dest, inputSize,
 515                 maxOutputSize, LZ4_ACCELERATION_DEFAULT, wrkmem);
 516 }
 517 EXPORT_SYMBOL(LZ4_compress_default);
 518 
 519 /*-******************************
 520  *      *_destSize() variant
 521  ********************************/
 522 static int LZ4_compress_destSize_generic(
 523         LZ4_stream_t_internal * const ctx,
 524         const char * const src,
 525         char * const dst,
 526         int * const srcSizePtr,
 527         const int targetDstSize,
 528         const tableType_t tableType)
 529 {
 530         const BYTE *ip = (const BYTE *) src;
 531         const BYTE *base = (const BYTE *) src;
 532         const BYTE *lowLimit = (const BYTE *) src;
 533         const BYTE *anchor = ip;
 534         const BYTE * const iend = ip + *srcSizePtr;
 535         const BYTE * const mflimit = iend - MFLIMIT;
 536         const BYTE * const matchlimit = iend - LASTLITERALS;
 537 
 538         BYTE *op = (BYTE *) dst;
 539         BYTE * const oend = op + targetDstSize;
 540         BYTE * const oMaxLit = op + targetDstSize - 2 /* offset */
 541                 - 8 /* because 8 + MINMATCH == MFLIMIT */ - 1 /* token */;
 542         BYTE * const oMaxMatch = op + targetDstSize
 543                 - (LASTLITERALS + 1 /* token */);
 544         BYTE * const oMaxSeq = oMaxLit - 1 /* token */;
 545 
 546         U32 forwardH;
 547 
 548         /* Init conditions */
 549         /* Impossible to store anything */
 550         if (targetDstSize < 1)
 551                 return 0;
 552         /* Unsupported input size, too large (or negative) */
 553         if ((U32)*srcSizePtr > (U32)LZ4_MAX_INPUT_SIZE)
 554                 return 0;
 555         /* Size too large (not within 64K limit) */
 556         if ((tableType == byU16) && (*srcSizePtr >= LZ4_64Klimit))
 557                 return 0;
 558         /* Input too small, no compression (all literals) */
 559         if (*srcSizePtr < LZ4_minLength)
 560                 goto _last_literals;
 561 
 562         /* First Byte */
 563         *srcSizePtr = 0;
 564         LZ4_putPosition(ip, ctx->hashTable, tableType, base);
 565         ip++; forwardH = LZ4_hashPosition(ip, tableType);
 566 
 567         /* Main Loop */
 568         for ( ; ; ) {
 569                 const BYTE *match;
 570                 BYTE *token;
 571 
 572                 /* Find a match */
 573                 {
 574                         const BYTE *forwardIp = ip;
 575                         unsigned int step = 1;
 576                         unsigned int searchMatchNb = 1 << LZ4_SKIPTRIGGER;
 577 
 578                         do {
 579                                 U32 h = forwardH;
 580 
 581                                 ip = forwardIp;
 582                                 forwardIp += step;
 583                                 step = (searchMatchNb++ >> LZ4_SKIPTRIGGER);
 584 
 585                                 if (unlikely(forwardIp > mflimit))
 586                                         goto _last_literals;
 587 
 588                                 match = LZ4_getPositionOnHash(h, ctx->hashTable,
 589                                         tableType, base);
 590                                 forwardH = LZ4_hashPosition(forwardIp,
 591                                         tableType);
 592                                 LZ4_putPositionOnHash(ip, h,
 593                                         ctx->hashTable, tableType,
 594                                         base);
 595 
 596                         } while (((tableType == byU16)
 597                                 ? 0
 598                                 : (match + MAX_DISTANCE < ip))
 599                                 || (LZ4_read32(match) != LZ4_read32(ip)));
 600                 }
 601 
 602                 /* Catch up */
 603                 while ((ip > anchor)
 604                         && (match > lowLimit)
 605                         && (unlikely(ip[-1] == match[-1]))) {
 606                         ip--;
 607                         match--;
 608                 }
 609 
 610                 /* Encode Literal length */
 611                 {
 612                         unsigned int litLength = (unsigned int)(ip - anchor);
 613 
 614                         token = op++;
 615                         if (op + ((litLength + 240) / 255)
 616                                 + litLength > oMaxLit) {
 617                                 /* Not enough space for a last match */
 618                                 op--;
 619                                 goto _last_literals;
 620                         }
 621                         if (litLength >= RUN_MASK) {
 622                                 unsigned int len = litLength - RUN_MASK;
 623                                 *token = (RUN_MASK<<ML_BITS);
 624                                 for (; len >= 255; len -= 255)
 625                                         *op++ = 255;
 626                                 *op++ = (BYTE)len;
 627                         } else
 628                                 *token = (BYTE)(litLength << ML_BITS);
 629 
 630                         /* Copy Literals */
 631                         LZ4_wildCopy(op, anchor, op + litLength);
 632                         op += litLength;
 633                 }
 634 
 635 _next_match:
 636                 /* Encode Offset */
 637                 LZ4_writeLE16(op, (U16)(ip - match)); op += 2;
 638 
 639                 /* Encode MatchLength */
 640                 {
 641                         size_t matchLength = LZ4_count(ip + MINMATCH,
 642                         match + MINMATCH, matchlimit);
 643 
 644                         if (op + ((matchLength + 240)/255) > oMaxMatch) {
 645                                 /* Match description too long : reduce it */
 646                                 matchLength = (15 - 1) + (oMaxMatch - op) * 255;
 647                         }
 648                         ip += MINMATCH + matchLength;
 649 
 650                         if (matchLength >= ML_MASK) {
 651                                 *token += ML_MASK;
 652                                 matchLength -= ML_MASK;
 653                                 while (matchLength >= 255) {
 654                                         matchLength -= 255;
 655                                         *op++ = 255;
 656                                 }
 657                                 *op++ = (BYTE)matchLength;
 658                         } else
 659                                 *token += (BYTE)(matchLength);
 660                 }
 661 
 662                 anchor = ip;
 663 
 664                 /* Test end of block */
 665                 if (ip > mflimit)
 666                         break;
 667                 if (op > oMaxSeq)
 668                         break;
 669 
 670                 /* Fill table */
 671                 LZ4_putPosition(ip - 2, ctx->hashTable, tableType, base);
 672 
 673                 /* Test next position */
 674                 match = LZ4_getPosition(ip, ctx->hashTable, tableType, base);
 675                 LZ4_putPosition(ip, ctx->hashTable, tableType, base);
 676 
 677                 if ((match + MAX_DISTANCE >= ip)
 678                         && (LZ4_read32(match) == LZ4_read32(ip))) {
 679                         token = op++; *token = 0;
 680                         goto _next_match;
 681                 }
 682 
 683                 /* Prepare next loop */
 684                 forwardH = LZ4_hashPosition(++ip, tableType);
 685         }
 686 
 687 _last_literals:
 688         /* Encode Last Literals */
 689         {
 690                 size_t lastRunSize = (size_t)(iend - anchor);
 691 
 692                 if (op + 1 /* token */
 693                         + ((lastRunSize + 240) / 255) /* litLength */
 694                         + lastRunSize /* literals */ > oend) {
 695                         /* adapt lastRunSize to fill 'dst' */
 696                         lastRunSize     = (oend - op) - 1;
 697                         lastRunSize -= (lastRunSize + 240) / 255;
 698                 }
 699                 ip = anchor + lastRunSize;
 700 
 701                 if (lastRunSize >= RUN_MASK) {
 702                         size_t accumulator = lastRunSize - RUN_MASK;
 703 
 704                         *op++ = RUN_MASK << ML_BITS;
 705                         for (; accumulator >= 255; accumulator -= 255)
 706                                 *op++ = 255;
 707                         *op++ = (BYTE) accumulator;
 708                 } else {
 709                         *op++ = (BYTE)(lastRunSize<<ML_BITS);
 710                 }
 711                 memcpy(op, anchor, lastRunSize);
 712                 op += lastRunSize;
 713         }
 714 
 715         /* End */
 716         *srcSizePtr = (int) (((const char *)ip) - src);
 717         return (int) (((char *)op) - dst);
 718 }
 719 
 720 static int LZ4_compress_destSize_extState(
 721         LZ4_stream_t *state,
 722         const char *src,
 723         char *dst,
 724         int *srcSizePtr,
 725         int targetDstSize)
 726 {
 727 #if LZ4_ARCH64
 728         const tableType_t tableType = byU32;
 729 #else
 730         const tableType_t tableType = byPtr;
 731 #endif
 732 
 733         LZ4_resetStream(state);
 734 
 735         if (targetDstSize >= LZ4_COMPRESSBOUND(*srcSizePtr)) {
 736                 /* compression success is guaranteed */
 737                 return LZ4_compress_fast_extState(
 738                         state, src, dst, *srcSizePtr,
 739                         targetDstSize, 1);
 740         } else {
 741                 if (*srcSizePtr < LZ4_64Klimit)
 742                         return LZ4_compress_destSize_generic(
 743                                 &state->internal_donotuse,
 744                                 src, dst, srcSizePtr,
 745                                 targetDstSize, byU16);
 746                 else
 747                         return LZ4_compress_destSize_generic(
 748                                 &state->internal_donotuse,
 749                                 src, dst, srcSizePtr,
 750                                 targetDstSize, tableType);
 751         }
 752 }
 753 
 754 
 755 int LZ4_compress_destSize(
 756         const char *src,
 757         char *dst,
 758         int *srcSizePtr,
 759         int targetDstSize,
 760         void *wrkmem)
 761 {
 762         return LZ4_compress_destSize_extState(wrkmem, src, dst, srcSizePtr,
 763                 targetDstSize);
 764 }
 765 EXPORT_SYMBOL(LZ4_compress_destSize);
 766 
 767 /*-******************************
 768  *      Streaming functions
 769  ********************************/
 770 void LZ4_resetStream(LZ4_stream_t *LZ4_stream)
 771 {
 772         memset(LZ4_stream, 0, sizeof(LZ4_stream_t));
 773 }
 774 
 775 int LZ4_loadDict(LZ4_stream_t *LZ4_dict,
 776         const char *dictionary, int dictSize)
 777 {
 778         LZ4_stream_t_internal *dict = &LZ4_dict->internal_donotuse;
 779         const BYTE *p = (const BYTE *)dictionary;
 780         const BYTE * const dictEnd = p + dictSize;
 781         const BYTE *base;
 782 
 783         if ((dict->initCheck)
 784                 || (dict->currentOffset > 1 * GB)) {
 785                 /* Uninitialized structure, or reuse overflow */
 786                 LZ4_resetStream(LZ4_dict);
 787         }
 788 
 789         if (dictSize < (int)HASH_UNIT) {
 790                 dict->dictionary = NULL;
 791                 dict->dictSize = 0;
 792                 return 0;
 793         }
 794 
 795         if ((dictEnd - p) > 64 * KB)
 796                 p = dictEnd - 64 * KB;
 797         dict->currentOffset += 64 * KB;
 798         base = p - dict->currentOffset;
 799         dict->dictionary = p;
 800         dict->dictSize = (U32)(dictEnd - p);
 801         dict->currentOffset += dict->dictSize;
 802 
 803         while (p <= dictEnd - HASH_UNIT) {
 804                 LZ4_putPosition(p, dict->hashTable, byU32, base);
 805                 p += 3;
 806         }
 807 
 808         return dict->dictSize;
 809 }
 810 EXPORT_SYMBOL(LZ4_loadDict);
 811 
 812 static void LZ4_renormDictT(LZ4_stream_t_internal *LZ4_dict,
 813         const BYTE *src)
 814 {
 815         if ((LZ4_dict->currentOffset > 0x80000000) ||
 816                 ((uptrval)LZ4_dict->currentOffset > (uptrval)src)) {
 817                 /* address space overflow */
 818                 /* rescale hash table */
 819                 U32 const delta = LZ4_dict->currentOffset - 64 * KB;
 820                 const BYTE *dictEnd = LZ4_dict->dictionary + LZ4_dict->dictSize;
 821                 int i;
 822 
 823                 for (i = 0; i < LZ4_HASH_SIZE_U32; i++) {
 824                         if (LZ4_dict->hashTable[i] < delta)
 825                                 LZ4_dict->hashTable[i] = 0;
 826                         else
 827                                 LZ4_dict->hashTable[i] -= delta;
 828                 }
 829                 LZ4_dict->currentOffset = 64 * KB;
 830                 if (LZ4_dict->dictSize > 64 * KB)
 831                         LZ4_dict->dictSize = 64 * KB;
 832                 LZ4_dict->dictionary = dictEnd - LZ4_dict->dictSize;
 833         }
 834 }
 835 
 836 int LZ4_saveDict(LZ4_stream_t *LZ4_dict, char *safeBuffer, int dictSize)
 837 {
 838         LZ4_stream_t_internal * const dict = &LZ4_dict->internal_donotuse;
 839         const BYTE * const previousDictEnd = dict->dictionary + dict->dictSize;
 840 
 841         if ((U32)dictSize > 64 * KB) {
 842                 /* useless to define a dictionary > 64 * KB */
 843                 dictSize = 64 * KB;
 844         }
 845         if ((U32)dictSize > dict->dictSize)
 846                 dictSize = dict->dictSize;
 847 
 848         memmove(safeBuffer, previousDictEnd - dictSize, dictSize);
 849 
 850         dict->dictionary = (const BYTE *)safeBuffer;
 851         dict->dictSize = (U32)dictSize;
 852 
 853         return dictSize;
 854 }
 855 EXPORT_SYMBOL(LZ4_saveDict);
 856 
 857 int LZ4_compress_fast_continue(LZ4_stream_t *LZ4_stream, const char *source,
 858         char *dest, int inputSize, int maxOutputSize, int acceleration)
 859 {
 860         LZ4_stream_t_internal *streamPtr = &LZ4_stream->internal_donotuse;
 861         const BYTE * const dictEnd = streamPtr->dictionary
 862                 + streamPtr->dictSize;
 863 
 864         const BYTE *smallest = (const BYTE *) source;
 865 
 866         if (streamPtr->initCheck) {
 867                 /* Uninitialized structure detected */
 868                 return 0;
 869         }
 870 
 871         if ((streamPtr->dictSize > 0) && (smallest > dictEnd))
 872                 smallest = dictEnd;
 873 
 874         LZ4_renormDictT(streamPtr, smallest);
 875 
 876         if (acceleration < 1)
 877                 acceleration = LZ4_ACCELERATION_DEFAULT;
 878 
 879         /* Check overlapping input/dictionary space */
 880         {
 881                 const BYTE *sourceEnd = (const BYTE *) source + inputSize;
 882 
 883                 if ((sourceEnd > streamPtr->dictionary)
 884                         && (sourceEnd < dictEnd)) {
 885                         streamPtr->dictSize = (U32)(dictEnd - sourceEnd);
 886                         if (streamPtr->dictSize > 64 * KB)
 887                                 streamPtr->dictSize = 64 * KB;
 888                         if (streamPtr->dictSize < 4)
 889                                 streamPtr->dictSize = 0;
 890                         streamPtr->dictionary = dictEnd - streamPtr->dictSize;
 891                 }
 892         }
 893 
 894         /* prefix mode : source data follows dictionary */
 895         if (dictEnd == (const BYTE *)source) {
 896                 int result;
 897 
 898                 if ((streamPtr->dictSize < 64 * KB) &&
 899                         (streamPtr->dictSize < streamPtr->currentOffset)) {
 900                         result = LZ4_compress_generic(
 901                                 streamPtr, source, dest, inputSize,
 902                                 maxOutputSize, limitedOutput, byU32,
 903                                 withPrefix64k, dictSmall, acceleration);
 904                 } else {
 905                         result = LZ4_compress_generic(
 906                                 streamPtr, source, dest, inputSize,
 907                                 maxOutputSize, limitedOutput, byU32,
 908                                 withPrefix64k, noDictIssue, acceleration);
 909                 }
 910                 streamPtr->dictSize += (U32)inputSize;
 911                 streamPtr->currentOffset += (U32)inputSize;
 912                 return result;
 913         }
 914 
 915         /* external dictionary mode */
 916         {
 917                 int result;
 918 
 919                 if ((streamPtr->dictSize < 64 * KB) &&
 920                         (streamPtr->dictSize < streamPtr->currentOffset)) {
 921                         result = LZ4_compress_generic(
 922                                 streamPtr, source, dest, inputSize,
 923                                 maxOutputSize, limitedOutput, byU32,
 924                                 usingExtDict, dictSmall, acceleration);
 925                 } else {
 926                         result = LZ4_compress_generic(
 927                                 streamPtr, source, dest, inputSize,
 928                                 maxOutputSize, limitedOutput, byU32,
 929                                 usingExtDict, noDictIssue, acceleration);
 930                 }
 931                 streamPtr->dictionary = (const BYTE *)source;
 932                 streamPtr->dictSize = (U32)inputSize;
 933                 streamPtr->currentOffset += (U32)inputSize;
 934                 return result;
 935         }
 936 }
 937 EXPORT_SYMBOL(LZ4_compress_fast_continue);
 938 
 939 MODULE_LICENSE("Dual BSD/GPL");
 940 MODULE_DESCRIPTION("LZ4 compressor");
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root/lib/lz4/lz4_compress.c

DEFINITIONS
