git.maemo.org Git - opencv/blob - 3rdparty/libtiff/tif_lzw.c

   1 /* $Id: tif_lzw.c,v 1.1 2005-06-17 13:54:52 vp153 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                 TIFFWarning(_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                 TIFFError("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                         TIFFError(module, "No space for LZW code table");
 228                         return (0);
 229                 }
 230                 /*
 231                  * Pre-load the table.
 232                  */
 233                 code = 255;
 234                 do {
 235                     sp->dec_codetab[code].value = code;
 236                     sp->dec_codetab[code].firstchar = code;
 237                     sp->dec_codetab[code].length = 1;
 238                     sp->dec_codetab[code].next = NULL;
 239                 } while (code--);
 240         }
 241         return (1);
 242 }
 243
 244 /*
 245  * Setup state for decoding a strip.
 246  */
 247 static int
 248 LZWPreDecode(TIFF* tif, tsample_t s)
 249 {
 250         LZWCodecState *sp = DecoderState(tif);
 251
 252         (void) s;
 253         assert(sp != NULL);
 254         /*
 255          * Check for old bit-reversed codes.
 256          */
 257         if (tif->tif_rawdata[0] == 0 && (tif->tif_rawdata[1] & 0x1)) {
 258 #ifdef LZW_COMPAT
 259                 if (!sp->dec_decode) {
 260                         TIFFWarning(tif->tif_name,
 261                             "Old-style LZW codes, convert file");
 262                         /*
 263                          * Override default decoding methods with
 264                          * ones that deal with the old coding.
 265                          * Otherwise the predictor versions set
 266                          * above will call the compatibility routines
 267                          * through the dec_decode method.
 268                          */
 269                         tif->tif_decoderow = LZWDecodeCompat;
 270                         tif->tif_decodestrip = LZWDecodeCompat;
 271                         tif->tif_decodetile = LZWDecodeCompat;
 272                         /*
 273                          * If doing horizontal differencing, must
 274                          * re-setup the predictor logic since we
 275                          * switched the basic decoder methods...
 276                          */
 277                         (*tif->tif_setupdecode)(tif);
 278                         sp->dec_decode = LZWDecodeCompat;
 279                 }
 280                 sp->lzw_maxcode = MAXCODE(BITS_MIN);
 281 #else /* !LZW_COMPAT */
 282                 if (!sp->dec_decode) {
 283                         TIFFError(tif->tif_name,
 284                             "Old-style LZW codes not supported");
 285                         sp->dec_decode = LZWDecode;
 286                 }
 287                 return (0);
 288 #endif/* !LZW_COMPAT */
 289         } else {
 290                 sp->lzw_maxcode = MAXCODE(BITS_MIN)-1;
 291                 sp->dec_decode = LZWDecode;
 292         }
 293         sp->lzw_nbits = BITS_MIN;
 294         sp->lzw_nextbits = 0;
 295         sp->lzw_nextdata = 0;
 296
 297         sp->dec_restart = 0;
 298         sp->dec_nbitsmask = MAXCODE(BITS_MIN);
 299 #ifdef LZW_CHECKEOS
 300         sp->dec_bitsleft = tif->tif_rawcc << 3;
 301 #endif
 302         sp->dec_free_entp = sp->dec_codetab + CODE_FIRST;
 303         /*
 304          * Zero entries that are not yet filled in.  We do
 305          * this to guard against bogus input data that causes
 306          * us to index into undefined entries.  If you can
 307          * come up with a way to safely bounds-check input codes
 308          * while decoding then you can remove this operation.
 309          */
 310         _TIFFmemset(sp->dec_free_entp, 0, (CSIZE-CODE_FIRST)*sizeof (code_t));
 311         sp->dec_oldcodep = &sp->dec_codetab[-1];
 312         sp->dec_maxcodep = &sp->dec_codetab[sp->dec_nbitsmask-1];
 313         return (1);
 314 }
 315
 316 /*
 317  * Decode a "hunk of data".
 318  */
 319 #define GetNextCode(sp, bp, code) {                             \
 320         nextdata = (nextdata<<8) | *(bp)++;                     \
 321         nextbits += 8;                                          \
 322         if (nextbits < nbits) {                                 \
 323                 nextdata = (nextdata<<8) | *(bp)++;             \
 324                 nextbits += 8;                                  \
 325         }                                                       \
 326         code = (hcode_t)((nextdata >> (nextbits-nbits)) & nbitsmask);   \
 327         nextbits -= nbits;                                      \
 328 }
 329
 330 static void
 331 codeLoop(TIFF* tif)
 332 {
 333         TIFFError(tif->tif_name,
 334             "LZWDecode: Bogus encoding, loop in the code table; scanline %d",
 335             tif->tif_row);
 336 }
 337
 338 static int
 339 LZWDecode(TIFF* tif, tidata_t op0, tsize_t occ0, tsample_t s)
 340 {
 341         LZWCodecState *sp = DecoderState(tif);
 342         char *op = (char*) op0;
 343         long occ = (long) occ0;
 344         char *tp;
 345         unsigned char *bp;
 346         hcode_t code;
 347         int len;
 348         long nbits, nextbits, nextdata, nbitsmask;
 349         code_t *codep, *free_entp, *maxcodep, *oldcodep;
 350
 351         (void) s;
 352         assert(sp != NULL);
 353         /*
 354          * Restart interrupted output operation.
 355          */
 356         if (sp->dec_restart) {
 357                 long residue;
 358
 359                 codep = sp->dec_codep;
 360                 residue = codep->length - sp->dec_restart;
 361                 if (residue > occ) {
 362                         /*
 363                          * Residue from previous decode is sufficient
 364                          * to satisfy decode request.  Skip to the
 365                          * start of the decoded string, place decoded
 366                          * values in the output buffer, and return.
 367                          */
 368                         sp->dec_restart += occ;
 369                         do {
 370                                 codep = codep->next;
 371                         } while (--residue > occ && codep);
 372                         if (codep) {
 373                                 tp = op + occ;
 374                                 do {
 375                                         *--tp = codep->value;
 376                                         codep = codep->next;
 377                                 } while (--occ && codep);
 378                         }
 379                         return (1);
 380                 }
 381                 /*
 382                  * Residue satisfies only part of the decode request.
 383                  */
 384                 op += residue, occ -= residue;
 385                 tp = op;
 386                 do {
 387                         int t;
 388                         --tp;
 389                         t = codep->value;
 390                         codep = codep->next;
 391                         *tp = t;
 392                 } while (--residue && codep);
 393                 sp->dec_restart = 0;
 394         }
 395
 396         bp = (unsigned char *)tif->tif_rawcp;
 397         nbits = sp->lzw_nbits;
 398         nextdata = sp->lzw_nextdata;
 399         nextbits = sp->lzw_nextbits;
 400         nbitsmask = sp->dec_nbitsmask;
 401         oldcodep = sp->dec_oldcodep;
 402         free_entp = sp->dec_free_entp;
 403         maxcodep = sp->dec_maxcodep;
 404
 405         while (occ > 0) {
 406                 NextCode(tif, sp, bp, code, GetNextCode);
 407                 if (code == CODE_EOI)
 408                         break;
 409                 if (code == CODE_CLEAR) {
 410                         free_entp = sp->dec_codetab + CODE_FIRST;
 411                         nbits = BITS_MIN;
 412                         nbitsmask = MAXCODE(BITS_MIN);
 413                         maxcodep = sp->dec_codetab + nbitsmask-1;
 414                         NextCode(tif, sp, bp, code, GetNextCode);
 415                         if (code == CODE_EOI)
 416                                 break;
 417                         *op++ = (char)code, occ--;
 418                         oldcodep = sp->dec_codetab + code;
 419                         continue;
 420                 }
 421                 codep = sp->dec_codetab + code;
 422
 423                 /*
 424                  * Add the new entry to the code table.
 425                  */
 426                 if (free_entp < &sp->dec_codetab[0] ||
 427                         free_entp >= &sp->dec_codetab[CSIZE]) {
 428                         TIFFError(tif->tif_name,
 429                         "LZWDecode: Corrupted LZW table at scanline %d",
 430                         tif->tif_row);
 431                         return (0);
 432                 }
 433
 434                 free_entp->next = oldcodep;
 435                 if (free_entp->next < &sp->dec_codetab[0] ||
 436                         free_entp->next >= &sp->dec_codetab[CSIZE]) {
 437                         TIFFError(tif->tif_name,
 438                         "LZWDecode: Corrupted LZW table at scanline %d",
 439                         tif->tif_row);
 440                         return (0);
 441                 }
 442                 free_entp->firstchar = free_entp->next->firstchar;
 443                 free_entp->length = free_entp->next->length+1;
 444                 free_entp->value = (codep < free_entp) ?
 445                     codep->firstchar : free_entp->firstchar;
 446                 if (++free_entp > maxcodep) {
 447                         if (++nbits > BITS_MAX)         /* should not happen */
 448                                 nbits = BITS_MAX;
 449                         nbitsmask = MAXCODE(nbits);
 450                         maxcodep = sp->dec_codetab + nbitsmask-1;
 451                 }
 452                 oldcodep = codep;
 453                 if (code >= 256) {
 454                         /*
 455                          * Code maps to a string, copy string
 456                          * value to output (written in reverse).
 457                          */
 458                         if(codep->length == 0) {
 459                             TIFFError(tif->tif_name,
 460                             "LZWDecode: Wrong length of decoded string: "
 461                             "data probably corrupted at scanline %d",
 462                             tif->tif_row);
 463                             return (0);
 464                         }
 465                         if (codep->length > occ) {
 466                                 /*
 467                                  * String is too long for decode buffer,
 468                                  * locate portion that will fit, copy to
 469                                  * the decode buffer, and setup restart
 470                                  * logic for the next decoding call.
 471                                  */
 472                                 sp->dec_codep = codep;
 473                                 do {
 474                                         codep = codep->next;
 475                                 } while (codep && codep->length > occ);
 476                                 if (codep) {
 477                                         sp->dec_restart = occ;
 478                                         tp = op + occ;
 479                                         do  {
 480                                                 *--tp = codep->value;
 481                                                 codep = codep->next;
 482                                         }  while (--occ && codep);
 483                                         if (codep)
 484                                                 codeLoop(tif);
 485                                 }
 486                                 break;
 487                         }
 488                         len = codep->length;
 489                         tp = op + len;
 490                         do {
 491                                 int t;
 492                                 --tp;
 493                                 t = codep->value;
 494                                 codep = codep->next;
 495                                 *tp = t;
 496                         } while (codep && tp > op);
 497                         if (codep) {
 498                             codeLoop(tif);
 499                             break;
 500                         }
 501                         op += len, occ -= len;
 502                 } else
 503                         *op++ = (char)code, occ--;
 504         }
 505
 506         tif->tif_rawcp = (tidata_t) bp;
 507         sp->lzw_nbits = (unsigned short) nbits;
 508         sp->lzw_nextdata = nextdata;
 509         sp->lzw_nextbits = nextbits;
 510         sp->dec_nbitsmask = nbitsmask;
 511         sp->dec_oldcodep = oldcodep;
 512         sp->dec_free_entp = free_entp;
 513         sp->dec_maxcodep = maxcodep;
 514
 515         if (occ > 0) {
 516                 TIFFError(tif->tif_name,
 517                 "LZWDecode: Not enough data at scanline %d (short %d bytes)",
 518                     tif->tif_row, occ);
 519                 return (0);
 520         }
 521         return (1);
 522 }
 523
 524 #ifdef LZW_COMPAT
 525 /*
 526  * Decode a "hunk of data" for old images.
 527  */
 528 #define GetNextCodeCompat(sp, bp, code) {                       \
 529         nextdata |= (unsigned long) *(bp)++ << nextbits;        \
 530         nextbits += 8;                                          \
 531         if (nextbits < nbits) {                                 \
 532                 nextdata |= (unsigned long) *(bp)++ << nextbits;\
 533                 nextbits += 8;                                  \
 534         }                                                       \
 535         code = (hcode_t)(nextdata & nbitsmask);                 \
 536         nextdata >>= nbits;                                     \
 537         nextbits -= nbits;                                      \
 538 }
 539
 540 static int
 541 LZWDecodeCompat(TIFF* tif, tidata_t op0, tsize_t occ0, tsample_t s)
 542 {
 543         LZWCodecState *sp = DecoderState(tif);
 544         char *op = (char*) op0;
 545         long occ = (long) occ0;
 546         char *tp;
 547         unsigned char *bp;
 548         int code, nbits;
 549         long nextbits, nextdata, nbitsmask;
 550         code_t *codep, *free_entp, *maxcodep, *oldcodep;
 551
 552         (void) s;
 553         assert(sp != NULL);
 554         /*
 555          * Restart interrupted output operation.
 556          */
 557         if (sp->dec_restart) {
 558                 long residue;
 559
 560                 codep = sp->dec_codep;
 561                 residue = codep->length - sp->dec_restart;
 562                 if (residue > occ) {
 563                         /*
 564                          * Residue from previous decode is sufficient
 565                          * to satisfy decode request.  Skip to the
 566                          * start of the decoded string, place decoded
 567                          * values in the output buffer, and return.
 568                          */
 569                         sp->dec_restart += occ;
 570                         do {
 571                                 codep = codep->next;
 572                         } while (--residue > occ);
 573                         tp = op + occ;
 574                         do {
 575                                 *--tp = codep->value;
 576                                 codep = codep->next;
 577                         } while (--occ);
 578                         return (1);
 579                 }
 580                 /*
 581                  * Residue satisfies only part of the decode request.
 582                  */
 583                 op += residue, occ -= residue;
 584                 tp = op;
 585                 do {
 586                         *--tp = codep->value;
 587                         codep = codep->next;
 588                 } while (--residue);
 589                 sp->dec_restart = 0;
 590         }
 591
 592         bp = (unsigned char *)tif->tif_rawcp;
 593         nbits = sp->lzw_nbits;
 594         nextdata = sp->lzw_nextdata;
 595         nextbits = sp->lzw_nextbits;
 596         nbitsmask = sp->dec_nbitsmask;
 597         oldcodep = sp->dec_oldcodep;
 598         free_entp = sp->dec_free_entp;
 599         maxcodep = sp->dec_maxcodep;
 600
 601         while (occ > 0) {
 602                 NextCode(tif, sp, bp, code, GetNextCodeCompat);
 603                 if (code == CODE_EOI)
 604                         break;
 605                 if (code == CODE_CLEAR) {
 606                         free_entp = sp->dec_codetab + CODE_FIRST;
 607                         nbits = BITS_MIN;
 608                         nbitsmask = MAXCODE(BITS_MIN);
 609                         maxcodep = sp->dec_codetab + nbitsmask;
 610                         NextCode(tif, sp, bp, code, GetNextCodeCompat);
 611                         if (code == CODE_EOI)
 612                                 break;
 613                         *op++ = code, occ--;
 614                         oldcodep = sp->dec_codetab + code;
 615                         continue;
 616                 }
 617                 codep = sp->dec_codetab + code;
 618
 619                 /*
 620                  * Add the new entry to the code table.
 621                  */
 622                 if (free_entp < &sp->dec_codetab[0] ||
 623                         free_entp >= &sp->dec_codetab[CSIZE]) {
 624                         TIFFError(tif->tif_name,
 625                         "LZWDecodeCompat: Corrupted LZW table at scanline %d",
 626                         tif->tif_row);
 627                         return (0);
 628                 }
 629
 630                 free_entp->next = oldcodep;
 631                 if (free_entp->next < &sp->dec_codetab[0] ||
 632                         free_entp->next >= &sp->dec_codetab[CSIZE]) {
 633                         TIFFError(tif->tif_name,
 634                         "LZWDecodeCompat: Corrupted LZW table at scanline %d",
 635                         tif->tif_row);
 636                         return (0);
 637                 }
 638                 free_entp->firstchar = free_entp->next->firstchar;
 639                 free_entp->length = free_entp->next->length+1;
 640                 free_entp->value = (codep < free_entp) ?
 641                     codep->firstchar : free_entp->firstchar;
 642                 if (++free_entp > maxcodep) {
 643                         if (++nbits > BITS_MAX)         /* should not happen */
 644                                 nbits = BITS_MAX;
 645                         nbitsmask = MAXCODE(nbits);
 646                         maxcodep = sp->dec_codetab + nbitsmask;
 647                 }
 648                 oldcodep = codep;
 649                 if (code >= 256) {
 650                         /*
 651                          * Code maps to a string, copy string
 652                          * value to output (written in reverse).
 653                          */
 654                         if(codep->length == 0) {
 655                             TIFFError(tif->tif_name,
 656                             "LZWDecodeCompat: Wrong length of decoded "
 657                             "string: data probably corrupted at scanline %d",
 658                             tif->tif_row);
 659                             return (0);
 660                         }
 661                         if (codep->length > occ) {
 662                                 /*
 663                                  * String is too long for decode buffer,
 664                                  * locate portion that will fit, copy to
 665                                  * the decode buffer, and setup restart
 666                                  * logic for the next decoding call.
 667                                  */
 668                                 sp->dec_codep = codep;
 669                                 do {
 670                                         codep = codep->next;
 671                                 } while (codep->length > occ);
 672                                 sp->dec_restart = occ;
 673                                 tp = op + occ;
 674                                 do  {
 675                                         *--tp = codep->value;
 676                                         codep = codep->next;
 677                                 }  while (--occ);
 678                                 break;
 679                         }
 680                         op += codep->length, occ -= codep->length;
 681                         tp = op;
 682                         do {
 683                                 *--tp = codep->value;
 684                         } while( (codep = codep->next) != NULL);
 685                 } else
 686                         *op++ = code, occ--;
 687         }
 688
 689         tif->tif_rawcp = (tidata_t) bp;
 690         sp->lzw_nbits = nbits;
 691         sp->lzw_nextdata = nextdata;
 692         sp->lzw_nextbits = nextbits;
 693         sp->dec_nbitsmask = nbitsmask;
 694         sp->dec_oldcodep = oldcodep;
 695         sp->dec_free_entp = free_entp;
 696         sp->dec_maxcodep = maxcodep;
 697
 698         if (occ > 0) {
 699                 TIFFError(tif->tif_name,
 700             "LZWDecodeCompat: Not enough data at scanline %d (short %d bytes)",
 701                     tif->tif_row, occ);
 702                 return (0);
 703         }
 704         return (1);
 705 }
 706 #endif /* LZW_COMPAT */
 707
 708 /*
 709  * LZW Encoding.
 710  */
 711
 712 static int
 713 LZWSetupEncode(TIFF* tif)
 714 {
 715         LZWCodecState* sp = EncoderState(tif);
 716         static const char module[] = "LZWSetupEncode";
 717
 718         assert(sp != NULL);
 719         sp->enc_hashtab = (hash_t*) _TIFFmalloc(HSIZE*sizeof (hash_t));
 720         if (sp->enc_hashtab == NULL) {
 721                 TIFFError(module, "No space for LZW hash table");
 722                 return (0);
 723         }
 724         return (1);
 725 }
 726
 727 /*
 728  * Reset encoding state at the start of a strip.
 729  */
 730 static int
 731 LZWPreEncode(TIFF* tif, tsample_t s)
 732 {
 733         LZWCodecState *sp = EncoderState(tif);
 734
 735         (void) s;
 736         assert(sp != NULL);
 737         sp->lzw_nbits = BITS_MIN;
 738         sp->lzw_maxcode = MAXCODE(BITS_MIN);
 739         sp->lzw_free_ent = CODE_FIRST;
 740         sp->lzw_nextbits = 0;
 741         sp->lzw_nextdata = 0;
 742         sp->enc_checkpoint = CHECK_GAP;
 743         sp->enc_ratio = 0;
 744         sp->enc_incount = 0;
 745         sp->enc_outcount = 0;
 746         /*
 747          * The 4 here insures there is space for 2 max-sized
 748          * codes in LZWEncode and LZWPostDecode.
 749          */
 750         sp->enc_rawlimit = tif->tif_rawdata + tif->tif_rawdatasize-1 - 4;
 751         cl_hash(sp);            /* clear hash table */
 752         sp->enc_oldcode = (hcode_t) -1; /* generates CODE_CLEAR in LZWEncode */
 753         return (1);
 754 }
 755
 756 #define CALCRATIO(sp, rat) {                                    \
 757         if (incount > 0x007fffff) { /* NB: shift will overflow */\
 758                 rat = outcount >> 8;                            \
 759                 rat = (rat == 0 ? 0x7fffffff : incount/rat);    \
 760         } else                                                  \
 761                 rat = (incount<<8) / outcount;                  \
 762 }
 763 #define PutNextCode(op, c) {                                    \
 764         nextdata = (nextdata << nbits) | c;                     \
 765         nextbits += nbits;                                      \
 766         *op++ = (unsigned char)(nextdata >> (nextbits-8));              \
 767         nextbits -= 8;                                          \
 768         if (nextbits >= 8) {                                    \
 769                 *op++ = (unsigned char)(nextdata >> (nextbits-8));      \
 770                 nextbits -= 8;                                  \
 771         }                                                       \
 772         outcount += nbits;                                      \
 773 }
 774
 775 /*
 776  * Encode a chunk of pixels.
 777  *
 778  * Uses an open addressing double hashing (no chaining) on the
 779  * prefix code/next character combination.  We do a variant of
 780  * Knuth's algorithm D (vol. 3, sec. 6.4) along with G. Knott's
 781  * relatively-prime secondary probe.  Here, the modular division
 782  * first probe is gives way to a faster exclusive-or manipulation.
 783  * Also do block compression with an adaptive reset, whereby the
 784  * code table is cleared when the compression ratio decreases,
 785  * but after the table fills.  The variable-length output codes
 786  * are re-sized at this point, and a CODE_CLEAR is generated
 787  * for the decoder.
 788  */
 789 static int
 790 LZWEncode(TIFF* tif, tidata_t bp, tsize_t cc, tsample_t s)
 791 {
 792         register LZWCodecState *sp = EncoderState(tif);
 793         register long fcode;
 794         register hash_t *hp;
 795         register int h, c;
 796         hcode_t ent;
 797         long disp;
 798         long incount, outcount, checkpoint;
 799         long nextdata, nextbits;
 800         int free_ent, maxcode, nbits;
 801         tidata_t op, limit;
 802
 803         (void) s;
 804         if (sp == NULL)
 805                 return (0);
 806         /*
 807          * Load local state.
 808          */
 809         incount = sp->enc_incount;
 810         outcount = sp->enc_outcount;
 811         checkpoint = sp->enc_checkpoint;
 812         nextdata = sp->lzw_nextdata;
 813         nextbits = sp->lzw_nextbits;
 814         free_ent = sp->lzw_free_ent;
 815         maxcode = sp->lzw_maxcode;
 816         nbits = sp->lzw_nbits;
 817         op = tif->tif_rawcp;
 818         limit = sp->enc_rawlimit;
 819         ent = sp->enc_oldcode;
 820
 821         if (ent == (hcode_t) -1 && cc > 0) {
 822                 /*
 823                  * NB: This is safe because it can only happen
 824                  *     at the start of a strip where we know there
 825                  *     is space in the data buffer.
 826                  */
 827                 PutNextCode(op, CODE_CLEAR);
 828                 ent = *bp++; cc--; incount++;
 829         }
 830         while (cc > 0) {
 831                 c = *bp++; cc--; incount++;
 832                 fcode = ((long)c << BITS_MAX) + ent;
 833                 h = (c << HSHIFT) ^ ent;        /* xor hashing */
 834 #ifdef _WINDOWS
 835                 /*
 836                  * Check hash index for an overflow.
 837                  */
 838                 if (h >= HSIZE)
 839                         h -= HSIZE;
 840 #endif
 841                 hp = &sp->enc_hashtab[h];
 842                 if (hp->hash == fcode) {
 843                         ent = hp->code;
 844                         continue;
 845                 }
 846                 if (hp->hash >= 0) {
 847                         /*
 848                          * Primary hash failed, check secondary hash.
 849                          */
 850                         disp = HSIZE - h;
 851                         if (h == 0)
 852                                 disp = 1;
 853                         do {
 854                                 /*
 855                                  * Avoid pointer arithmetic 'cuz of
 856                                  * wraparound problems with segments.
 857                                  */
 858                                 if ((h -= disp) < 0)
 859                                         h += HSIZE;
 860                                 hp = &sp->enc_hashtab[h];
 861                                 if (hp->hash == fcode) {
 862                                         ent = hp->code;
 863                                         goto hit;
 864                                 }
 865                         } while (hp->hash >= 0);
 866                 }
 867                 /*
 868                  * New entry, emit code and add to table.
 869                  */
 870                 /*
 871                  * Verify there is space in the buffer for the code
 872                  * and any potential Clear code that might be emitted
 873                  * below.  The value of limit is setup so that there
 874                  * are at least 4 bytes free--room for 2 codes.
 875                  */
 876                 if (op > limit) {
 877                         tif->tif_rawcc = (tsize_t)(op - tif->tif_rawdata);
 878                         TIFFFlushData1(tif);
 879                         op = tif->tif_rawdata;
 880                 }
 881                 PutNextCode(op, ent);
 882                 ent = c;
 883                 hp->code = free_ent++;
 884                 hp->hash = fcode;
 885                 if (free_ent == CODE_MAX-1) {
 886                         /* table is full, emit clear code and reset */
 887                         cl_hash(sp);
 888                         sp->enc_ratio = 0;
 889                         incount = 0;
 890                         outcount = 0;
 891                         free_ent = CODE_FIRST;
 892                         PutNextCode(op, CODE_CLEAR);
 893                         nbits = BITS_MIN;
 894                         maxcode = MAXCODE(BITS_MIN);
 895                 } else {
 896                         /*
 897                          * If the next entry is going to be too big for
 898                          * the code size, then increase it, if possible.
 899                          */
 900                         if (free_ent > maxcode) {
 901                                 nbits++;
 902                                 assert(nbits <= BITS_MAX);
 903                                 maxcode = (int) MAXCODE(nbits);
 904                         } else if (incount >= checkpoint) {
 905                                 long rat;
 906                                 /*
 907                                  * Check compression ratio and, if things seem
 908                                  * to be slipping, clear the hash table and
 909                                  * reset state.  The compression ratio is a
 910                                  * 24+8-bit fractional number.
 911                                  */
 912                                 checkpoint = incount+CHECK_GAP;
 913                                 CALCRATIO(sp, rat);
 914                                 if (rat <= sp->enc_ratio) {
 915                                         cl_hash(sp);
 916                                         sp->enc_ratio = 0;
 917                                         incount = 0;
 918                                         outcount = 0;
 919                                         free_ent = CODE_FIRST;
 920                                         PutNextCode(op, CODE_CLEAR);
 921                                         nbits = BITS_MIN;
 922                                         maxcode = MAXCODE(BITS_MIN);
 923                                 } else
 924                                         sp->enc_ratio = rat;
 925                         }
 926                 }
 927         hit:
 928                 ;
 929         }
 930
 931         /*
 932          * Restore global state.
 933          */
 934         sp->enc_incount = incount;
 935         sp->enc_outcount = outcount;
 936         sp->enc_checkpoint = checkpoint;
 937         sp->enc_oldcode = ent;
 938         sp->lzw_nextdata = nextdata;
 939         sp->lzw_nextbits = nextbits;
 940         sp->lzw_free_ent = free_ent;
 941         sp->lzw_maxcode = maxcode;
 942         sp->lzw_nbits = nbits;
 943         tif->tif_rawcp = op;
 944         return (1);
 945 }
 946
 947 /*
 948  * Finish off an encoded strip by flushing the last
 949  * string and tacking on an End Of Information code.
 950  */
 951 static int
 952 LZWPostEncode(TIFF* tif)
 953 {
 954         register LZWCodecState *sp = EncoderState(tif);
 955         tidata_t op = tif->tif_rawcp;
 956         long nextbits = sp->lzw_nextbits;
 957         long nextdata = sp->lzw_nextdata;
 958         long outcount = sp->enc_outcount;
 959         int nbits = sp->lzw_nbits;
 960
 961         if (op > sp->enc_rawlimit) {
 962                 tif->tif_rawcc = (tsize_t)(op - tif->tif_rawdata);
 963                 TIFFFlushData1(tif);
 964                 op = tif->tif_rawdata;
 965         }
 966         if (sp->enc_oldcode != (hcode_t) -1) {
 967                 PutNextCode(op, sp->enc_oldcode);
 968                 sp->enc_oldcode = (hcode_t) -1;
 969         }
 970         PutNextCode(op, CODE_EOI);
 971         if (nextbits > 0)
 972                 *op++ = (unsigned char)(nextdata << (8-nextbits));
 973         tif->tif_rawcc = (tsize_t)(op - tif->tif_rawdata);
 974         return (1);
 975 }
 976
 977 /*
 978  * Reset encoding hash table.
 979  */
 980 static void
 981 cl_hash(LZWCodecState* sp)
 982 {
 983         register hash_t *hp = &sp->enc_hashtab[HSIZE-1];
 984         register long i = HSIZE-8;
 985
 986         do {
 987                 i -= 8;
 988                 hp[-7].hash = -1;
 989                 hp[-6].hash = -1;
 990                 hp[-5].hash = -1;
 991                 hp[-4].hash = -1;
 992                 hp[-3].hash = -1;
 993                 hp[-2].hash = -1;
 994                 hp[-1].hash = -1;
 995                 hp[ 0].hash = -1;
 996                 hp -= 8;
 997         } while (i >= 0);
 998         for (i += 8; i > 0; i--, hp--)
 999                 hp->hash = -1;
1000 }
1001
1002 static void
1003 LZWCleanup(TIFF* tif)
1004 {
1005         if (tif->tif_data) {
1006                 if (DecoderState(tif)->dec_codetab)
1007                         _TIFFfree(DecoderState(tif)->dec_codetab);
1008
1009                 if (EncoderState(tif)->enc_hashtab)
1010                         _TIFFfree(EncoderState(tif)->enc_hashtab);
1011
1012                 _TIFFfree(tif->tif_data);
1013                 tif->tif_data = NULL;
1014         }
1015 }
1016
1017 int
1018 TIFFInitLZW(TIFF* tif, int scheme)
1019 {
1020         assert(scheme == COMPRESSION_LZW);
1021         /*
1022          * Allocate state block so tag methods have storage to record values.
1023          */
1024         tif->tif_data = (tidata_t) _TIFFmalloc(sizeof (LZWCodecState));
1025         if (tif->tif_data == NULL)
1026                 goto bad;
1027         DecoderState(tif)->dec_codetab = NULL;
1028         DecoderState(tif)->dec_decode = NULL;
1029         EncoderState(tif)->enc_hashtab = NULL;
1030         LZWState(tif)->rw_mode = tif->tif_mode;
1031
1032         /*
1033          * Install codec methods.
1034          */
1035         tif->tif_setupdecode = LZWSetupDecode;
1036         tif->tif_predecode = LZWPreDecode;
1037         tif->tif_decoderow = LZWDecode;
1038         tif->tif_decodestrip = LZWDecode;
1039         tif->tif_decodetile = LZWDecode;
1040         tif->tif_setupencode = LZWSetupEncode;
1041         tif->tif_preencode = LZWPreEncode;
1042         tif->tif_postencode = LZWPostEncode;
1043         tif->tif_encoderow = LZWEncode;
1044         tif->tif_encodestrip = LZWEncode;
1045         tif->tif_encodetile = LZWEncode;
1046         tif->tif_cleanup = LZWCleanup;
1047         /*
1048          * Setup predictor setup.
1049          */
1050         (void) TIFFPredictorInit(tif);
1051         return (1);
1052 bad:
1053         TIFFError("TIFFInitLZW", "No space for LZW state block");
1054         return (0);
1055 }
1056
1057 /*
1058  * Copyright (c) 1985, 1986 The Regents of the University of California.
1059  * All rights reserved.
1060  *
1061  * This code is derived from software contributed to Berkeley by
1062  * James A. Woods, derived from original work by Spencer Thomas
1063  * and Joseph Orost.
1064  *
1065  * Redistribution and use in source and binary forms are permitted
1066  * provided that the above copyright notice and this paragraph are
1067  * duplicated in all such forms and that any documentation,
1068  * advertising materials, and other materials related to such
1069  * distribution and use acknowledge that the software was developed
1070  * by the University of California, Berkeley.  The name of the
1071  * University may not be used to endorse or promote products derived
1072  * from this software without specific prior written permission.
1073  * THIS SOFTWARE IS PROVIDED ``AS IS'' AND WITHOUT ANY EXPRESS OR
1074  * IMPLIED WARRANTIES, INCLUDING, WITHOUT LIMITATION, THE IMPLIED
1075  * WARRANTIES OF MERCHANTIBILITY AND FITNESS FOR A PARTICULAR PURPOSE.
1076  */
1077 #endif /* LZW_SUPPORT */
1078
1079 /* vim: set ts=8 sts=8 sw=8 noet: */