GNU Linux-libre 4.19.211-gnu1
[releases.git] / lib / lz4 / 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/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");