thirdparty/libtiff/tif_lzw.c

   1 /* $Id: tif_lzw.c,v 1.29.2.6 2010-06-08 18:50:42 bfriesen Exp $ */
   2
   3 /*
   4  * Copyright (c) 1988-1997 Sam Leffler
   5  * Copyright (c) 1991-1997 Silicon Graphics, Inc.
   6  *
   7  * Permission to use, copy, modify, distribute, and sell this software and
   8  * its documentation for any purpose is hereby granted without fee, provided
   9  * that (i) the above copyright notices and this permission notice appear in
  10  * all copies of the software and related documentation, and (ii) the names of
  11  * Sam Leffler and Silicon Graphics may not be used in any advertising or
  12  * publicity relating to the software without the specific, prior written
  13  * permission of Sam Leffler and Silicon Graphics.
  14  *
  15  * THE SOFTWARE IS PROVIDED "AS-IS" AND WITHOUT WARRANTY OF ANY KIND,
  16  * EXPRESS, IMPLIED OR OTHERWISE, INCLUDING WITHOUT LIMITATION, ANY
  17  * WARRANTY OF MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE.
  18  *
  19  * IN NO EVENT SHALL SAM LEFFLER OR SILICON GRAPHICS BE LIABLE FOR
  20  * ANY SPECIAL, INCIDENTAL, INDIRECT OR CONSEQUENTIAL DAMAGES OF ANY KIND,
  21  * OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS,
  22  * WHETHER OR NOT ADVISED OF THE POSSIBILITY OF DAMAGE, AND ON ANY THEORY OF
  23  * LIABILITY, ARISING OUT OF OR IN CONNECTION WITH THE USE OR PERFORMANCE
  24  * OF THIS SOFTWARE.
  25  */
  26
  27 #include "tiffiop.h"
  28 #ifdef LZW_SUPPORT
  29 /*
  30  * TIFF Library.
  31  * Rev 5.0 Lempel-Ziv & Welch Compression Support
  32  *
  33  * This code is derived from the compress program whose code is
  34  * derived from software contributed to Berkeley by James A. Woods,
  35  * derived from original work by Spencer Thomas and Joseph Orost.
  36  *
  37  * The original Berkeley copyright notice appears below in its entirety.
  38  */
  39 #include "tif_predict.h"
  40
  41 #include <stdio.h>
  42
  43 /*
  44  * NB: The 5.0 spec describes a different algorithm than Aldus
  45  *     implements.  Specifically, Aldus does code length transitions
  46  *     one code earlier than should be done (for real LZW).
  47  *     Earlier versions of this library implemented the correct
  48  *     LZW algorithm, but emitted codes in a bit order opposite
  49  *     to the TIFF spec.  Thus, to maintain compatibility w/ Aldus
  50  *     we interpret MSB-LSB ordered codes to be images written w/
  51  *     old versions of this library, but otherwise adhere to the
  52  *     Aldus "off by one" algorithm.
  53  *
  54  * Future revisions to the TIFF spec are expected to "clarify this issue".
  55  */
  56 #define LZW_COMPAT              /* include backwards compatibility code */
  57 /*
  58  * Each strip of data is supposed to be terminated by a CODE_EOI.
  59  * If the following #define is included, the decoder will also
  60  * check for end-of-strip w/o seeing this code.  This makes the
  61  * library more robust, but also slower.
  62  */
  63 #define LZW_CHECKEOS            /* include checks for strips w/o EOI code */
  64
  65 #define MAXCODE(n)      ((1L<<(n))-1)
  66 /*
  67  * The TIFF spec specifies that encoded bit
  68  * strings range from 9 to 12 bits.
  69  */
  70 #define BITS_MIN        9               /* start with 9 bits */
  71 #define BITS_MAX        12              /* max of 12 bit strings */
  72 /* predefined codes */
  73 #define CODE_CLEAR      256             /* code to clear string table */
  74 #define CODE_EOI        257             /* end-of-information code */
  75 #define CODE_FIRST      258             /* first free code entry */
  76 #define CODE_MAX        MAXCODE(BITS_MAX)
  77 #define HSIZE           9001L           /* 91% occupancy */
  78 #define HSHIFT          (13-8)
  79 #ifdef LZW_COMPAT
  80 /* NB: +1024 is for compatibility with old files */
  81 #define CSIZE           (MAXCODE(BITS_MAX)+1024L)
  82 #else
  83 #define CSIZE           (MAXCODE(BITS_MAX)+1L)
  84 #endif
  85
  86 /*
  87  * State block for each open TIFF file using LZW
  88  * compression/decompression.  Note that the predictor
  89  * state block must be first in this data structure.
  90  */
  91 typedef struct {
  92         TIFFPredictorState predict;     /* predictor super class */
  93
  94         unsigned short  nbits;          /* # of bits/code */
  95         unsigned short  maxcode;        /* maximum code for lzw_nbits */
  96         unsigned short  free_ent;       /* next free entry in hash table */
  97         long            nextdata;       /* next bits of i/o */
  98         long            nextbits;       /* # of valid bits in lzw_nextdata */
  99
 100         int             rw_mode;        /* preserve rw_mode from init */
 101 } LZWBaseState;
 102
 103 #define lzw_nbits       base.nbits
 104 #define lzw_maxcode     base.maxcode
 105 #define lzw_free_ent    base.free_ent
 106 #define lzw_nextdata    base.nextdata
 107 #define lzw_nextbits    base.nextbits
 108
 109 /*
 110  * Encoding-specific state.
 111  */
 112 typedef uint16 hcode_t;                 /* codes fit in 16 bits */
 113 typedef struct {
 114         long    hash;
 115         hcode_t code;
 116 } hash_t;
 117
 118 /*
 119  * Decoding-specific state.
 120  */
 121 typedef struct code_ent {
 122         struct code_ent *next;
 123         unsigned short  length;         /* string len, including this token */
 124         unsigned char   value;          /* data value */
 125         unsigned char   firstchar;      /* first token of string */
 126 } code_t;
 127
 128 typedef int (*decodeFunc)(TIFF*, tidata_t, tsize_t, tsample_t);
 129
 130 typedef struct {
 131         LZWBaseState base;
 132
 133         /* Decoding specific data */
 134         long    dec_nbitsmask;          /* lzw_nbits 1 bits, right adjusted */
 135         long    dec_restart;            /* restart count */
 136 #ifdef LZW_CHECKEOS
 137         long    dec_bitsleft;           /* available bits in raw data */
 138 #endif
 139         decodeFunc dec_decode;          /* regular or backwards compatible */
 140         code_t* dec_codep;              /* current recognized code */
 141         code_t* dec_oldcodep;           /* previously recognized code */
 142         code_t* dec_free_entp;          /* next free entry */
 143         code_t* dec_maxcodep;           /* max available entry */
 144         code_t* dec_codetab;            /* kept separate for small machines */
 145
 146         /* Encoding specific data */
 147         int     enc_oldcode;            /* last code encountered */
 148         long    enc_checkpoint;         /* point at which to clear table */
 149 #define CHECK_GAP       10000           /* enc_ratio check interval */
 150         long    enc_ratio;              /* current compression ratio */
 151         long    enc_incount;            /* (input) data bytes encoded */
 152         long    enc_outcount;           /* encoded (output) bytes */
 153         tidata_t enc_rawlimit;          /* bound on tif_rawdata buffer */
 154         hash_t* enc_hashtab;            /* kept separate for small machines */
 155 } LZWCodecState;
 156
 157 #define LZWState(tif)           ((LZWBaseState*) (tif)->tif_data)
 158 #define DecoderState(tif)       ((LZWCodecState*) LZWState(tif))
 159 #define EncoderState(tif)       ((LZWCodecState*) LZWState(tif))
 160
 161 static  int LZWDecode(TIFF*, tidata_t, tsize_t, tsample_t);
 162 #ifdef LZW_COMPAT
 163 static  int LZWDecodeCompat(TIFF*, tidata_t, tsize_t, tsample_t);
 164 #endif
 165 static  void cl_hash(LZWCodecState*);
 166
 167 /*
 168  * LZW Decoder.
 169  */
 170
 171 #ifdef LZW_CHECKEOS
 172 /*
 173  * This check shouldn't be necessary because each
 174  * strip is suppose to be terminated with CODE_EOI.
 175  */
 176 #define NextCode(_tif, _sp, _bp, _code, _get) {                         \
 177         if ((_sp)->dec_bitsleft < nbits) {                              \
 178                 TIFFWarningExt(_tif->tif_clientdata, _tif->tif_name,                            \
 179                     "LZWDecode: Strip %d not terminated with EOI code", \
 180                     _tif->tif_curstrip);                                \
 181                 _code = CODE_EOI;                                       \
 182         } else {                                                        \
 183                 _get(_sp,_bp,_code);                                    \
 184                 (_sp)->dec_bitsleft -= nbits;                           \
 185         }                                                               \
 186 }
 187 #else
 188 #define NextCode(tif, sp, bp, code, get) get(sp, bp, code)
 189 #endif
 190
 191 static int
 192 LZWSetupDecode(TIFF* tif)
 193 {
 194         LZWCodecState* sp = DecoderState(tif);
 195         static const char module[] = " LZWSetupDecode";
 196         int code;
 197
 198         if( sp == NULL )
 199         {
 200             /*
 201              * Allocate state block so tag methods have storage to record
 202                          * values.
 203              */
 204             tif->tif_data = (tidata_t) _TIFFmalloc(sizeof(LZWCodecState));
 205             if (tif->tif_data == NULL)
 206             {
 207                                 TIFFErrorExt(tif->tif_clientdata, "LZWPreDecode", "No space for LZW state block");
 208                 return (0);
 209             }
 210
 211             DecoderState(tif)->dec_codetab = NULL;
 212             DecoderState(tif)->dec_decode = NULL;
 213
 214             /*
 215              * Setup predictor setup.
 216              */
 217             (void) TIFFPredictorInit(tif);
 218
 219             sp = DecoderState(tif);
 220         }
 221
 222         assert(sp != NULL);
 223
 224         if (sp->dec_codetab == NULL) {
 225                 sp->dec_codetab = (code_t*)_TIFFmalloc(CSIZE*sizeof (code_t));
 226                 if (sp->dec_codetab == NULL) {
 227                         TIFFErrorExt(tif->tif_clientdata, module,
 228                                      "No space for LZW code table");
 229                         return (0);
 230                 }
 231                 /*
 232                  * Pre-load the table.
 233                  */
 234                 code = 255;
 235                 do {
 236                     sp->dec_codetab[code].value = code;
 237                     sp->dec_codetab[code].firstchar = code;
 238                     sp->dec_codetab[code].length = 1;
 239                     sp->dec_codetab[code].next = NULL;
 240                 } while (code--);
 241                 /*
 242                  * Zero-out the unused entries
 243                  */
 244                  _TIFFmemset(&sp->dec_codetab[CODE_CLEAR], 0,
 245                              (CODE_FIRST - CODE_CLEAR) * sizeof (code_t));
 246         }
 247         return (1);
 248 }
 249
 250 /*
 251  * Setup state for decoding a strip.
 252  */
 253 static int
 254 LZWPreDecode(TIFF* tif, tsample_t s)
 255 {
 256         LZWCodecState *sp = DecoderState(tif);
 257
 258         (void) s;
 259         assert(sp != NULL);
 260         if( sp->dec_codetab == NULL )
 261         {
 262             tif->tif_setupdecode( tif );
 263         }
 264
 265         /*
 266          * Check for old bit-reversed codes.
 267          */
 268         if (tif->tif_rawdata[0] == 0 && (tif->tif_rawdata[1] & 0x1)) {
 269 #ifdef LZW_COMPAT
 270                 if (!sp->dec_decode) {
 271                         TIFFWarningExt(tif->tif_clientdata, tif->tif_name,
 272                             "Old-style LZW codes, convert file");
 273                         /*
 274                          * Override default decoding methods with
 275                          * ones that deal with the old coding.
 276                          * Otherwise the predictor versions set
 277                          * above will call the compatibility routines
 278                          * through the dec_decode method.
 279                          */
 280                         tif->tif_decoderow = LZWDecodeCompat;
 281                         tif->tif_decodestrip = LZWDecodeCompat;
 282                         tif->tif_decodetile = LZWDecodeCompat;
 283                         /*
 284                          * If doing horizontal differencing, must
 285                          * re-setup the predictor logic since we
 286                          * switched the basic decoder methods...
 287                          */
 288                         (*tif->tif_setupdecode)(tif);
 289                         sp->dec_decode = LZWDecodeCompat;
 290                 }
 291                 sp->lzw_maxcode = MAXCODE(BITS_MIN);
 292 #else /* !LZW_COMPAT */
 293                 if (!sp->dec_decode) {
 294                         TIFFErrorExt(tif->tif_clientdata, tif->tif_name,
 295                             "Old-style LZW codes not supported");
 296                         sp->dec_decode = LZWDecode;
 297                 }
 298                 return (0);
 299 #endif/* !LZW_COMPAT */
 300         } else {
 301                 sp->lzw_maxcode = MAXCODE(BITS_MIN)-1;
 302                 sp->dec_decode = LZWDecode;
 303         }
 304         sp->lzw_nbits = BITS_MIN;
 305         sp->lzw_nextbits = 0;
 306         sp->lzw_nextdata = 0;
 307
 308         sp->dec_restart = 0;
 309         sp->dec_nbitsmask = MAXCODE(BITS_MIN);
 310 #ifdef LZW_CHECKEOS
 311         sp->dec_bitsleft = tif->tif_rawcc << 3;
 312 #endif
 313         sp->dec_free_entp = sp->dec_codetab + CODE_FIRST;
 314         /*
 315          * Zero entries that are not yet filled in.  We do
 316          * this to guard against bogus input data that causes
 317          * us to index into undefined entries.  If you can
 318          * come up with a way to safely bounds-check input codes
 319          * while decoding then you can remove this operation.
 320          */
 321         _TIFFmemset(sp->dec_free_entp, 0, (CSIZE-CODE_FIRST)*sizeof (code_t));
 322         sp->dec_oldcodep = &sp->dec_codetab[-1];
 323         sp->dec_maxcodep = &sp->dec_codetab[sp->dec_nbitsmask-1];
 324         return (1);
 325 }
 326
 327 /*
 328  * Decode a "hunk of data".
 329  */
 330 #define GetNextCode(sp, bp, code) {                             \
 331         nextdata = (nextdata<<8) | *(bp)++;                     \
 332         nextbits += 8;                                          \
 333         if (nextbits < nbits) {                                 \
 334                 nextdata = (nextdata<<8) | *(bp)++;             \
 335                 nextbits += 8;                                  \
 336         }                                                       \
 337         code = (hcode_t)((nextdata >> (nextbits-nbits)) & nbitsmask);   \
 338         nextbits -= nbits;                                      \
 339 }
 340
 341 static void
 342 codeLoop(TIFF* tif)
 343 {
 344         TIFFErrorExt(tif->tif_clientdata, tif->tif_name,
 345             "LZWDecode: Bogus encoding, loop in the code table; scanline %d",
 346             tif->tif_row);
 347 }
 348
 349 static int
 350 LZWDecode(TIFF* tif, tidata_t op0, tsize_t occ0, tsample_t s)
 351 {
 352         LZWCodecState *sp = DecoderState(tif);
 353         char *op = (char*) op0;
 354         long occ = (long) occ0;
 355         char *tp;
 356         unsigned char *bp;
 357         hcode_t code;
 358         int len;
 359         long nbits, nextbits, nextdata, nbitsmask;
 360         code_t *codep, *free_entp, *maxcodep, *oldcodep;
 361
 362         (void) s;
 363         assert(sp != NULL);
 364         assert(sp->dec_codetab != NULL);
 365         /*
 366          * Restart interrupted output operation.
 367          */
 368         if (sp->dec_restart) {
 369                 long residue;
 370
 371                 codep = sp->dec_codep;
 372                 residue = codep->length - sp->dec_restart;
 373                 if (residue > occ) {
 374                         /*
 375                          * Residue from previous decode is sufficient
 376                          * to satisfy decode request.  Skip to the
 377                          * start of the decoded string, place decoded
 378                          * values in the output buffer, and return.
 379                          */
 380                         sp->dec_restart += occ;
 381                         do {
 382                                 codep = codep->next;
 383                         } while (--residue > occ && codep);
 384                         if (codep) {
 385                                 tp = op + occ;
 386                                 do {
 387                                         *--tp = codep->value;
 388                                         codep = codep->next;
 389                                 } while (--occ && codep);
 390                         }
 391                         return (1);
 392                 }
 393                 /*
 394                  * Residue satisfies only part of the decode request.
 395                  */
 396                 op += residue, occ -= residue;
 397                 tp = op;
 398                 do {
 399                         int t;
 400                         --tp;
 401                         t = codep->value;
 402                         codep = codep->next;
 403                         *tp = t;
 404                 } while (--residue && codep);
 405                 sp->dec_restart = 0;
 406         }
 407
 408         bp = (unsigned char *)tif->tif_rawcp;
 409         nbits = sp->lzw_nbits;
 410         nextdata = sp->lzw_nextdata;
 411         nextbits = sp->lzw_nextbits;
 412         nbitsmask = sp->dec_nbitsmask;
 413         oldcodep = sp->dec_oldcodep;
 414         free_entp = sp->dec_free_entp;
 415         maxcodep = sp->dec_maxcodep;
 416
 417         while (occ > 0) {
 418                 NextCode(tif, sp, bp, code, GetNextCode);
 419                 if (code == CODE_EOI)
 420                         break;
 421                 if (code == CODE_CLEAR) {
 422                         free_entp = sp->dec_codetab + CODE_FIRST;
 423                         _TIFFmemset(free_entp, 0,
 424                                     (CSIZE - CODE_FIRST) * sizeof (code_t));
 425                         nbits = BITS_MIN;
 426                         nbitsmask = MAXCODE(BITS_MIN);
 427                         maxcodep = sp->dec_codetab + nbitsmask-1;
 428                         NextCode(tif, sp, bp, code, GetNextCode);
 429                         if (code == CODE_EOI)
 430                                 break;
 431                         if (code == CODE_CLEAR) {
 432                                 TIFFErrorExt(tif->tif_clientdata, tif->tif_name,
 433                                 "LZWDecode: Corrupted LZW table at scanline %d",
 434                                              tif->tif_row);
 435                                 return (0);
 436                         }
 437                         *op++ = (char)code, occ--;
 438                         oldcodep = sp->dec_codetab + code;
 439                         continue;
 440                 }
 441                 codep = sp->dec_codetab + code;
 442
 443                 /*
 444                  * Add the new entry to the code table.
 445                  */
 446                 if (free_entp < &sp->dec_codetab[0] ||
 447                         free_entp >= &sp->dec_codetab[CSIZE]) {
 448                         TIFFErrorExt(tif->tif_clientdata, tif->tif_name,
 449                         "LZWDecode: Corrupted LZW table at scanline %d",
 450                         tif->tif_row);
 451                         return (0);
 452                 }
 453
 454                 free_entp->next = oldcodep;
 455                 if (free_entp->next < &sp->dec_codetab[0] ||
 456                         free_entp->next >= &sp->dec_codetab[CSIZE]) {
 457                         TIFFErrorExt(tif->tif_clientdata, tif->tif_name,
 458                         "LZWDecode: Corrupted LZW table at scanline %d",
 459                         tif->tif_row);
 460                         return (0);
 461                 }
 462                 free_entp->firstchar = free_entp->next->firstchar;
 463                 free_entp->length = free_entp->next->length+1;
 464                 free_entp->value = (codep < free_entp) ?
 465                     codep->firstchar : free_entp->firstchar;
 466                 if (++free_entp > maxcodep) {
 467                         if (++nbits > BITS_MAX)         /* should not happen */
 468                                 nbits = BITS_MAX;
 469                         nbitsmask = MAXCODE(nbits);
 470                         maxcodep = sp->dec_codetab + nbitsmask-1;
 471                 }
 472                 oldcodep = codep;
 473                 if (code >= 256) {
 474                         /*
 475                          * Code maps to a string, copy string
 476                          * value to output (written in reverse).
 477                          */
 478                         if(codep->length == 0) {
 479                                 TIFFErrorExt(tif->tif_clientdata, tif->tif_name,
 480                             "LZWDecode: Wrong length of decoded string: "
 481                             "data probably corrupted at scanline %d",
 482                             tif->tif_row);
 483                             return (0);
 484                         }
 485                         if (codep->length > occ) {
 486                                 /*
 487                                  * String is too long for decode buffer,
 488                                  * locate portion that will fit, copy to
 489                                  * the decode buffer, and setup restart
 490                                  * logic for the next decoding call.
 491                                  */
 492                                 sp->dec_codep = codep;
 493                                 do {
 494                                         codep = codep->next;
 495                                 } while (codep && codep->length > occ);
 496                                 if (codep) {
 497                                         sp->dec_restart = occ;
 498                                         tp = op + occ;
 499                                         do  {
 500                                                 *--tp = codep->value;
 501                                                 codep = codep->next;
 502                                         }  while (--occ && codep);
 503                                         if (codep)
 504                                                 codeLoop(tif);
 505                                 }
 506                                 break;
 507                         }
 508                         len = codep->length;
 509                         tp = op + len;
 510                         do {
 511                                 int t;
 512                                 --tp;
 513                                 t = codep->value;
 514                                 codep = codep->next;
 515                                 *tp = t;
 516                         } while (codep && tp > op);
 517                         if (codep) {
 518                             codeLoop(tif);
 519                             break;
 520                         }
 521                         op += len, occ -= len;
 522                 } else
 523                         *op++ = (char)code, occ--;
 524         }
 525
 526         tif->tif_rawcp = (tidata_t) bp;
 527         sp->lzw_nbits = (unsigned short) nbits;
 528         sp->lzw_nextdata = nextdata;
 529         sp->lzw_nextbits = nextbits;
 530         sp->dec_nbitsmask = nbitsmask;
 531         sp->dec_oldcodep = oldcodep;
 532         sp->dec_free_entp = free_entp;
 533         sp->dec_maxcodep = maxcodep;
 534
 535         if (occ > 0) {
 536                 TIFFErrorExt(tif->tif_clientdata, tif->tif_name,
 537                 "LZWDecode: Not enough data at scanline %d (short %ld bytes)",
 538                     tif->tif_row, occ);
 539                 return (0);
 540         }
 541         return (1);
 542 }
 543
 544 #ifdef LZW_COMPAT
 545 /*
 546  * Decode a "hunk of data" for old images.
 547  */
 548 #define GetNextCodeCompat(sp, bp, code) {                       \
 549         nextdata |= (unsigned long) *(bp)++ << nextbits;        \
 550         nextbits += 8;                                          \
 551         if (nextbits < nbits) {                                 \
 552                 nextdata |= (unsigned long) *(bp)++ << nextbits;\
 553                 nextbits += 8;                                  \
 554         }                                                       \
 555         code = (hcode_t)(nextdata & nbitsmask);                 \
 556         nextdata >>= nbits;                                     \
 557         nextbits -= nbits;                                      \
 558 }
 559
 560 static int
 561 LZWDecodeCompat(TIFF* tif, tidata_t op0, tsize_t occ0, tsample_t s)
 562 {
 563         LZWCodecState *sp = DecoderState(tif);
 564         char *op = (char*) op0;
 565         long occ = (long) occ0;
 566         char *tp;
 567         unsigned char *bp;
 568         int code, nbits;
 569         long nextbits, nextdata, nbitsmask;
 570         code_t *codep, *free_entp, *maxcodep, *oldcodep;
 571
 572         (void) s;
 573         assert(sp != NULL);
 574         /*
 575          * Restart interrupted output operation.
 576          */
 577         if (sp->dec_restart) {
 578                 long residue;
 579
 580                 codep = sp->dec_codep;
 581                 residue = codep->length - sp->dec_restart;
 582                 if (residue > occ) {
 583                         /*
 584                          * Residue from previous decode is sufficient
 585                          * to satisfy decode request.  Skip to the
 586                          * start of the decoded string, place decoded
 587                          * values in the output buffer, and return.
 588                          */
 589                         sp->dec_restart += occ;
 590                         do {
 591                                 codep = codep->next;
 592                         } while (--residue > occ);
 593                         tp = op + occ;
 594                         do {
 595                                 *--tp = codep->value;
 596                                 codep = codep->next;
 597                         } while (--occ);
 598                         return (1);
 599                 }
 600                 /*
 601                  * Residue satisfies only part of the decode request.
 602                  */
 603                 op += residue, occ -= residue;
 604                 tp = op;
 605                 do {
 606                         *--tp = codep->value;
 607                         codep = codep->next;
 608                 } while (--residue);
 609                 sp->dec_restart = 0;
 610         }
 611
 612         bp = (unsigned char *)tif->tif_rawcp;
 613         nbits = sp->lzw_nbits;
 614         nextdata = sp->lzw_nextdata;
 615         nextbits = sp->lzw_nextbits;
 616         nbitsmask = sp->dec_nbitsmask;
 617         oldcodep = sp->dec_oldcodep;
 618         free_entp = sp->dec_free_entp;
 619         maxcodep = sp->dec_maxcodep;
 620
 621         while (occ > 0) {
 622                 NextCode(tif, sp, bp, code, GetNextCodeCompat);
 623                 if (code == CODE_EOI)
 624                         break;
 625                 if (code == CODE_CLEAR) {
 626                         free_entp = sp->dec_codetab + CODE_FIRST;
 627                         _TIFFmemset(free_entp, 0,
 628                                     (CSIZE - CODE_FIRST) * sizeof (code_t));
 629                         nbits = BITS_MIN;
 630                         nbitsmask = MAXCODE(BITS_MIN);
 631                         maxcodep = sp->dec_codetab + nbitsmask;
 632                         NextCode(tif, sp, bp, code, GetNextCodeCompat);
 633                         if (code == CODE_EOI)
 634                                 break;
 635                         if (code == CODE_CLEAR) {
 636                                 TIFFErrorExt(tif->tif_clientdata, tif->tif_name,
 637                                 "LZWDecode: Corrupted LZW table at scanline %d",
 638                                              tif->tif_row);
 639                                 return (0);
 640                         }
 641                         *op++ = code, occ--;
 642                         oldcodep = sp->dec_codetab + code;
 643                         continue;
 644                 }
 645                 codep = sp->dec_codetab + code;
 646
 647                 /*
 648                  * Add the new entry to the code table.
 649                  */
 650                 if (free_entp < &sp->dec_codetab[0] ||
 651                         free_entp >= &sp->dec_codetab[CSIZE]) {
 652                         TIFFErrorExt(tif->tif_clientdata, tif->tif_name,
 653                         "LZWDecodeCompat: Corrupted LZW table at scanline %d",
 654                         tif->tif_row);
 655                         return (0);
 656                 }
 657
 658                 free_entp->next = oldcodep;
 659                 if (free_entp->next < &sp->dec_codetab[0] ||
 660                         free_entp->next >= &sp->dec_codetab[CSIZE]) {
 661                         TIFFErrorExt(tif->tif_clientdata, tif->tif_name,
 662                         "LZWDecodeCompat: Corrupted LZW table at scanline %d",
 663                         tif->tif_row);
 664                         return (0);
 665                 }
 666                 free_entp->firstchar = free_entp->next->firstchar;
 667                 free_entp->length = free_entp->next->length+1;
 668                 free_entp->value = (codep < free_entp) ?
 669                     codep->firstchar : free_entp->firstchar;
 670                 if (++free_entp > maxcodep) {
 671                         if (++nbits > BITS_MAX)         /* should not happen */
 672                                 nbits = BITS_MAX;
 673                         nbitsmask = MAXCODE(nbits);
 674                         maxcodep = sp->dec_codetab + nbitsmask;
 675                 }
 676                 oldcodep = codep;
 677                 if (code >= 256) {
 678                         char *op_orig = op;
 679                         /*
 680                          * Code maps to a string, copy string
 681                          * value to output (written in reverse).
 682                          */
 683                         if(codep->length == 0) {
 684                                 TIFFErrorExt(tif->tif_clientdata, tif->tif_name,
 685                             "LZWDecodeCompat: Wrong length of decoded "
 686                             "string: data probably corrupted at scanline %d",
 687                             tif->tif_row);
 688                             return (0);
 689                         }
 690                         if (codep->length > occ) {
 691                                 /*
 692                                  * String is too long for decode buffer,
 693                                  * locate portion that will fit, copy to
 694                                  * the decode buffer, and setup restart
 695                                  * logic for the next decoding call.
 696                                  */
 697                                 sp->dec_codep = codep;
 698                                 do {
 699                                         codep = codep->next;
 700                                 } while (codep->length > occ);
 701                                 sp->dec_restart = occ;
 702                                 tp = op + occ;
 703                                 do  {
 704                                         *--tp = codep->value;
 705                                         codep = codep->next;
 706                                 }  while (--occ);
 707                                 break;
 708                         }
 709                         op += codep->length, occ -= codep->length;
 710                         tp = op;
 711                         do {
 712                                 *--tp = codep->value;
 713                         } while( (codep = codep->next) != NULL && tp > op_orig);
 714                 } else
 715                         *op++ = code, occ--;
 716         }
 717
 718         tif->tif_rawcp = (tidata_t) bp;
 719         sp->lzw_nbits = nbits;
 720         sp->lzw_nextdata = nextdata;
 721         sp->lzw_nextbits = nextbits;
 722         sp->dec_nbitsmask = nbitsmask;
 723         sp->dec_oldcodep = oldcodep;
 724         sp->dec_free_entp = free_entp;
 725         sp->dec_maxcodep = maxcodep;
 726
 727         if (occ > 0) {
 728                 TIFFErrorExt(tif->tif_clientdata, tif->tif_name,
 729             "LZWDecodeCompat: Not enough data at scanline %d (short %ld bytes)",
 730                     tif->tif_row, occ);
 731                 return (0);
 732         }
 733         return (1);
 734 }
 735 #endif /* LZW_COMPAT */
 736
 737 /*
 738  * LZW Encoding.
 739  */
 740
 741 static int
 742 LZWSetupEncode(TIFF* tif)
 743 {
 744         LZWCodecState* sp = EncoderState(tif);
 745         static const char module[] = "LZWSetupEncode";
 746
 747         assert(sp != NULL);
 748         sp->enc_hashtab = (hash_t*) _TIFFmalloc(HSIZE*sizeof (hash_t));
 749         if (sp->enc_hashtab == NULL) {
 750                 TIFFErrorExt(tif->tif_clientdata, module, "No space for LZW hash table");
 751                 return (0);
 752         }
 753         return (1);
 754 }
 755
 756 /*
 757  * Reset encoding state at the start of a strip.
 758  */
 759 static int
 760 LZWPreEncode(TIFF* tif, tsample_t s)
 761 {
 762         LZWCodecState *sp = EncoderState(tif);
 763
 764         (void) s;
 765         assert(sp != NULL);
 766
 767         if( sp->enc_hashtab == NULL )
 768         {
 769             tif->tif_setupencode( tif );
 770         }
 771
 772         sp->lzw_nbits = BITS_MIN;
 773         sp->lzw_maxcode = MAXCODE(BITS_MIN);
 774         sp->lzw_free_ent = CODE_FIRST;
 775         sp->lzw_nextbits = 0;
 776         sp->lzw_nextdata = 0;
 777         sp->enc_checkpoint = CHECK_GAP;
 778         sp->enc_ratio = 0;
 779         sp->enc_incount = 0;
 780         sp->enc_outcount = 0;
 781         /*
 782          * The 4 here insures there is space for 2 max-sized
 783          * codes in LZWEncode and LZWPostDecode.
 784          */
 785         sp->enc_rawlimit = tif->tif_rawdata + tif->tif_rawdatasize-1 - 4;
 786         cl_hash(sp);            /* clear hash table */
 787         sp->enc_oldcode = (hcode_t) -1; /* generates CODE_CLEAR in LZWEncode */
 788         return (1);
 789 }
 790
 791 #define CALCRATIO(sp, rat) {                                    \
 792         if (incount > 0x007fffff) { /* NB: shift will overflow */\
 793                 rat = outcount >> 8;                            \
 794                 rat = (rat == 0 ? 0x7fffffff : incount/rat);    \
 795         } else                                                  \
 796                 rat = (incount<<8) / outcount;                  \
 797 }
 798 #define PutNextCode(op, c) {                                    \
 799         nextdata = (nextdata << nbits) | c;                     \
 800         nextbits += nbits;                                      \
 801         *op++ = (unsigned char)(nextdata >> (nextbits-8));              \
 802         nextbits -= 8;                                          \
 803         if (nextbits >= 8) {                                    \
 804                 *op++ = (unsigned char)(nextdata >> (nextbits-8));      \
 805                 nextbits -= 8;                                  \
 806         }                                                       \
 807         outcount += nbits;                                      \
 808 }
 809
 810 /*
 811  * Encode a chunk of pixels.
 812  *
 813  * Uses an open addressing double hashing (no chaining) on the
 814  * prefix code/next character combination.  We do a variant of
 815  * Knuth's algorithm D (vol. 3, sec. 6.4) along with G. Knott's
 816  * relatively-prime secondary probe.  Here, the modular division
 817  * first probe is gives way to a faster exclusive-or manipulation.
 818  * Also do block compression with an adaptive reset, whereby the
 819  * code table is cleared when the compression ratio decreases,
 820  * but after the table fills.  The variable-length output codes
 821  * are re-sized at this point, and a CODE_CLEAR is generated
 822  * for the decoder.
 823  */
 824 static int
 825 LZWEncode(TIFF* tif, tidata_t bp, tsize_t cc, tsample_t s)
 826 {
 827         register LZWCodecState *sp = EncoderState(tif);
 828         register long fcode;
 829         register hash_t *hp;
 830         register int h, c;
 831         hcode_t ent;
 832         long disp;
 833         long incount, outcount, checkpoint;
 834         long nextdata, nextbits;
 835         int free_ent, maxcode, nbits;
 836         tidata_t op, limit;
 837
 838         (void) s;
 839         if (sp == NULL)
 840                 return (0);
 841
 842         assert(sp->enc_hashtab != NULL);
 843
 844         /*
 845          * Load local state.
 846          */
 847         incount = sp->enc_incount;
 848         outcount = sp->enc_outcount;
 849         checkpoint = sp->enc_checkpoint;
 850         nextdata = sp->lzw_nextdata;
 851         nextbits = sp->lzw_nextbits;
 852         free_ent = sp->lzw_free_ent;
 853         maxcode = sp->lzw_maxcode;
 854         nbits = sp->lzw_nbits;
 855         op = tif->tif_rawcp;
 856         limit = sp->enc_rawlimit;
 857         ent = sp->enc_oldcode;
 858
 859         if (ent == (hcode_t) -1 && cc > 0) {
 860                 /*
 861                  * NB: This is safe because it can only happen
 862                  *     at the start of a strip where we know there
 863                  *     is space in the data buffer.
 864                  */
 865                 PutNextCode(op, CODE_CLEAR);
 866                 ent = *bp++; cc--; incount++;
 867         }
 868         while (cc > 0) {
 869                 c = *bp++; cc--; incount++;
 870                 fcode = ((long)c << BITS_MAX) + ent;
 871                 h = (c << HSHIFT) ^ ent;        /* xor hashing */
 872 #ifdef _WINDOWS
 873                 /*
 874                  * Check hash index for an overflow.
 875                  */
 876                 if (h >= HSIZE)
 877                         h -= HSIZE;
 878 #endif
 879                 hp = &sp->enc_hashtab[h];
 880                 if (hp->hash == fcode) {
 881                         ent = hp->code;
 882                         continue;
 883                 }
 884                 if (hp->hash >= 0) {
 885                         /*
 886                          * Primary hash failed, check secondary hash.
 887                          */
 888                         disp = HSIZE - h;
 889                         if (h == 0)
 890                                 disp = 1;
 891                         do {
 892                                 /*
 893                                  * Avoid pointer arithmetic 'cuz of
 894                                  * wraparound problems with segments.
 895                                  */
 896                                 if ((h -= disp) < 0)
 897                                         h += HSIZE;
 898                                 hp = &sp->enc_hashtab[h];
 899                                 if (hp->hash == fcode) {
 900                                         ent = hp->code;
 901                                         goto hit;
 902                                 }
 903                         } while (hp->hash >= 0);
 904                 }
 905                 /*
 906                  * New entry, emit code and add to table.
 907                  */
 908                 /*
 909                  * Verify there is space in the buffer for the code
 910                  * and any potential Clear code that might be emitted
 911                  * below.  The value of limit is setup so that there
 912                  * are at least 4 bytes free--room for 2 codes.
 913                  */
 914                 if (op > limit) {
 915                         tif->tif_rawcc = (tsize_t)(op - tif->tif_rawdata);
 916                         TIFFFlushData1(tif);
 917                         op = tif->tif_rawdata;
 918                 }
 919                 PutNextCode(op, ent);
 920                 ent = c;
 921                 hp->code = free_ent++;
 922                 hp->hash = fcode;
 923                 if (free_ent == CODE_MAX-1) {
 924                         /* table is full, emit clear code and reset */
 925                         cl_hash(sp);
 926                         sp->enc_ratio = 0;
 927                         incount = 0;
 928                         outcount = 0;
 929                         free_ent = CODE_FIRST;
 930                         PutNextCode(op, CODE_CLEAR);
 931                         nbits = BITS_MIN;
 932                         maxcode = MAXCODE(BITS_MIN);
 933                 } else {
 934                         /*
 935                          * If the next entry is going to be too big for
 936                          * the code size, then increase it, if possible.
 937                          */
 938                         if (free_ent > maxcode) {
 939                                 nbits++;
 940                                 assert(nbits <= BITS_MAX);
 941                                 maxcode = (int) MAXCODE(nbits);
 942                         } else if (incount >= checkpoint) {
 943                                 long rat;
 944                                 /*
 945                                  * Check compression ratio and, if things seem
 946                                  * to be slipping, clear the hash table and
 947                                  * reset state.  The compression ratio is a
 948                                  * 24+8-bit fractional number.
 949                                  */
 950                                 checkpoint = incount+CHECK_GAP;
 951                                 CALCRATIO(sp, rat);
 952                                 if (rat <= sp->enc_ratio) {
 953                                         cl_hash(sp);
 954                                         sp->enc_ratio = 0;
 955                                         incount = 0;
 956                                         outcount = 0;
 957                                         free_ent = CODE_FIRST;
 958                                         PutNextCode(op, CODE_CLEAR);
 959                                         nbits = BITS_MIN;
 960                                         maxcode = MAXCODE(BITS_MIN);
 961                                 } else
 962                                         sp->enc_ratio = rat;
 963                         }
 964                 }
 965         hit:
 966                 ;
 967         }
 968
 969         /*
 970          * Restore global state.
 971          */
 972         sp->enc_incount = incount;
 973         sp->enc_outcount = outcount;
 974         sp->enc_checkpoint = checkpoint;
 975         sp->enc_oldcode = ent;
 976         sp->lzw_nextdata = nextdata;
 977         sp->lzw_nextbits = nextbits;
 978         sp->lzw_free_ent = free_ent;
 979         sp->lzw_maxcode = maxcode;
 980         sp->lzw_nbits = nbits;
 981         tif->tif_rawcp = op;
 982         return (1);
 983 }
 984
 985 /*
 986  * Finish off an encoded strip by flushing the last
 987  * string and tacking on an End Of Information code.
 988  */
 989 static int
 990 LZWPostEncode(TIFF* tif)
 991 {
 992         register LZWCodecState *sp = EncoderState(tif);
 993         tidata_t op = tif->tif_rawcp;
 994         long nextbits = sp->lzw_nextbits;
 995         long nextdata = sp->lzw_nextdata;
 996         long outcount = sp->enc_outcount;
 997         int nbits = sp->lzw_nbits;
 998
 999         if (op > sp->enc_rawlimit) {
1000                 tif->tif_rawcc = (tsize_t)(op - tif->tif_rawdata);
1001                 TIFFFlushData1(tif);
1002                 op = tif->tif_rawdata;
1003         }
1004         if (sp->enc_oldcode != (hcode_t) -1) {
1005                 PutNextCode(op, sp->enc_oldcode);
1006                 sp->enc_oldcode = (hcode_t) -1;
1007         }
1008         PutNextCode(op, CODE_EOI);
1009         if (nextbits > 0)
1010                 *op++ = (unsigned char)(nextdata << (8-nextbits));
1011         tif->tif_rawcc = (tsize_t)(op - tif->tif_rawdata);
1012         return (1);
1013 }
1014
1015 /*
1016  * Reset encoding hash table.
1017  */
1018 static void
1019 cl_hash(LZWCodecState* sp)
1020 {
1021         register hash_t *hp = &sp->enc_hashtab[HSIZE-1];
1022         register long i = HSIZE-8;
1023
1024         do {
1025                 i -= 8;
1026                 hp[-7].hash = -1;
1027                 hp[-6].hash = -1;
1028                 hp[-5].hash = -1;
1029                 hp[-4].hash = -1;
1030                 hp[-3].hash = -1;
1031                 hp[-2].hash = -1;
1032                 hp[-1].hash = -1;
1033                 hp[ 0].hash = -1;
1034                 hp -= 8;
1035         } while (i >= 0);
1036         for (i += 8; i > 0; i--, hp--)
1037                 hp->hash = -1;
1038 }
1039
1040 static void
1041 LZWCleanup(TIFF* tif)
1042 {
1043         (void)TIFFPredictorCleanup(tif);
1044
1045         assert(tif->tif_data != 0);
1046
1047         if (DecoderState(tif)->dec_codetab)
1048                 _TIFFfree(DecoderState(tif)->dec_codetab);
1049
1050         if (EncoderState(tif)->enc_hashtab)
1051                 _TIFFfree(EncoderState(tif)->enc_hashtab);
1052
1053         _TIFFfree(tif->tif_data);
1054         tif->tif_data = NULL;
1055
1056         _TIFFSetDefaultCompressionState(tif);
1057 }
1058
1059 int
1060 TIFFInitLZW(TIFF* tif, int scheme)
1061 {
1062         assert(scheme == COMPRESSION_LZW);
1063         /*
1064          * Allocate state block so tag methods have storage to record values.
1065          */
1066         tif->tif_data = (tidata_t) _TIFFmalloc(sizeof (LZWCodecState));
1067         if (tif->tif_data == NULL)
1068                 goto bad;
1069         DecoderState(tif)->dec_codetab = NULL;
1070         DecoderState(tif)->dec_decode = NULL;
1071         EncoderState(tif)->enc_hashtab = NULL;
1072         LZWState(tif)->rw_mode = tif->tif_mode;
1073
1074         /*
1075          * Install codec methods.
1076          */
1077         tif->tif_setupdecode = LZWSetupDecode;
1078         tif->tif_predecode = LZWPreDecode;
1079         tif->tif_decoderow = LZWDecode;
1080         tif->tif_decodestrip = LZWDecode;
1081         tif->tif_decodetile = LZWDecode;
1082         tif->tif_setupencode = LZWSetupEncode;
1083         tif->tif_preencode = LZWPreEncode;
1084         tif->tif_postencode = LZWPostEncode;
1085         tif->tif_encoderow = LZWEncode;
1086         tif->tif_encodestrip = LZWEncode;
1087         tif->tif_encodetile = LZWEncode;
1088         tif->tif_cleanup = LZWCleanup;
1089         /*
1090          * Setup predictor setup.
1091          */
1092         (void) TIFFPredictorInit(tif);
1093         return (1);
1094 bad:
1095         TIFFErrorExt(tif->tif_clientdata, "TIFFInitLZW",
1096                      "No space for LZW state block");
1097         return (0);
1098 }
1099
1100 /*
1101  * Copyright (c) 1985, 1986 The Regents of the University of California.
1102  * All rights reserved.
1103  *
1104  * This code is derived from software contributed to Berkeley by
1105  * James A. Woods, derived from original work by Spencer Thomas
1106  * and Joseph Orost.
1107  *
1108  * Redistribution and use in source and binary forms are permitted
1109  * provided that the above copyright notice and this paragraph are
1110  * duplicated in all such forms and that any documentation,
1111  * advertising materials, and other materials related to such
1112  * distribution and use acknowledge that the software was developed
1113  * by the University of California, Berkeley.  The name of the
1114  * University may not be used to endorse or promote products derived
1115  * from this software without specific prior written permission.
1116  * THIS SOFTWARE IS PROVIDED ``AS IS'' AND WITHOUT ANY EXPRESS OR
1117  * IMPLIED WARRANTIES, INCLUDING, WITHOUT LIMITATION, THE IMPLIED
1118  * WARRANTIES OF MERCHANTIBILITY AND FITNESS FOR A PARTICULAR PURPOSE.
1119  */
1120 #endif /* LZW_SUPPORT */
1121
1122 /* vim: set ts=8 sts=8 sw=8 noet: */
1123 /*
1124  * Local Variables:
1125  * mode: c
1126  * c-basic-offset: 8
1127  * fill-column: 78
1128  * End:
1129  */