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/* $Id: tif_lzw.c,v 1.29.2.5 2009-06-22 04:57:31 fwarmerdam Exp $ */
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* Copyright (c) 1988-1997 Sam Leffler
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* Copyright (c) 1991-1997 Silicon Graphics, Inc.
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* Permission to use, copy, modify, distribute, and sell this software and
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* its documentation for any purpose is hereby granted without fee, provided
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* that (i) the above copyright notices and this permission notice appear in
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* all copies of the software and related documentation, and (ii) the names of
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* Sam Leffler and Silicon Graphics may not be used in any advertising or
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* publicity relating to the software without the specific, prior written
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* permission of Sam Leffler and Silicon Graphics.
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* THE SOFTWARE IS PROVIDED "AS-IS" AND WITHOUT WARRANTY OF ANY KIND,
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* EXPRESS, IMPLIED OR OTHERWISE, INCLUDING WITHOUT LIMITATION, ANY
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* WARRANTY OF MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE.
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* IN NO EVENT SHALL SAM LEFFLER OR SILICON GRAPHICS BE LIABLE FOR
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* ANY SPECIAL, INCIDENTAL, INDIRECT OR CONSEQUENTIAL DAMAGES OF ANY KIND,
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* OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS,
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* WHETHER OR NOT ADVISED OF THE POSSIBILITY OF DAMAGE, AND ON ANY THEORY OF
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* LIABILITY, ARISING OUT OF OR IN CONNECTION WITH THE USE OR PERFORMANCE
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* Rev 5.0 Lempel-Ziv & Welch Compression Support
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* This code is derived from the compress program whose code is
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* derived from software contributed to Berkeley by James A. Woods,
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* derived from original work by Spencer Thomas and Joseph Orost.
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* The original Berkeley copyright notice appears below in its entirety.
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#include "tif_predict.h"
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* NB: The 5.0 spec describes a different algorithm than Aldus
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* implements. Specifically, Aldus does code length transitions
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* one code earlier than should be done (for real LZW).
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* Earlier versions of this library implemented the correct
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* LZW algorithm, but emitted codes in a bit order opposite
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* to the TIFF spec. Thus, to maintain compatibility w/ Aldus
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* we interpret MSB-LSB ordered codes to be images written w/
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* old versions of this library, but otherwise adhere to the
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* Aldus "off by one" algorithm.
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* Future revisions to the TIFF spec are expected to "clarify this issue".
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#define LZW_COMPAT /* include backwards compatibility code */
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* Each strip of data is supposed to be terminated by a CODE_EOI.
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* If the following #define is included, the decoder will also
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* check for end-of-strip w/o seeing this code. This makes the
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* library more robust, but also slower.
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#define LZW_CHECKEOS /* include checks for strips w/o EOI code */
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#define MAXCODE(n) ((1L<<(n))-1)
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* The TIFF spec specifies that encoded bit
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* strings range from 9 to 12 bits.
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#define BITS_MIN 9 /* start with 9 bits */
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#define BITS_MAX 12 /* max of 12 bit strings */
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/* predefined codes */
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#define CODE_CLEAR 256 /* code to clear string table */
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#define CODE_EOI 257 /* end-of-information code */
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#define CODE_FIRST 258 /* first free code entry */
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#define CODE_MAX MAXCODE(BITS_MAX)
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#define HSIZE 9001L /* 91% occupancy */
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/* NB: +1024 is for compatibility with old files */
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#define CSIZE (MAXCODE(BITS_MAX)+1024L)
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#define CSIZE (MAXCODE(BITS_MAX)+1L)
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* State block for each open TIFF file using LZW
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* compression/decompression. Note that the predictor
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* state block must be first in this data structure.
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TIFFPredictorState predict; /* predictor super class */
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unsigned short nbits; /* # of bits/code */
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unsigned short maxcode; /* maximum code for lzw_nbits */
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unsigned short free_ent; /* next free entry in hash table */
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long nextdata; /* next bits of i/o */
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long nextbits; /* # of valid bits in lzw_nextdata */
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int rw_mode; /* preserve rw_mode from init */
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#define lzw_nbits base.nbits
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#define lzw_maxcode base.maxcode
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#define lzw_free_ent base.free_ent
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#define lzw_nextdata base.nextdata
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#define lzw_nextbits base.nextbits
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* Encoding-specific state.
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typedef uint16 hcode_t; /* codes fit in 16 bits */
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* Decoding-specific state.
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typedef struct code_ent {
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struct code_ent *next;
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unsigned short length; /* string len, including this token */
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unsigned char value; /* data value */
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unsigned char firstchar; /* first token of string */
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typedef int (*decodeFunc)(TIFF*, tidata_t, tsize_t, tsample_t);
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/* Decoding specific data */
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long dec_nbitsmask; /* lzw_nbits 1 bits, right adjusted */
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long dec_restart; /* restart count */
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long dec_bitsleft; /* available bits in raw data */
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decodeFunc dec_decode; /* regular or backwards compatible */
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code_t* dec_codep; /* current recognized code */
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code_t* dec_oldcodep; /* previously recognized code */
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code_t* dec_free_entp; /* next free entry */
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code_t* dec_maxcodep; /* max available entry */
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code_t* dec_codetab; /* kept separate for small machines */
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/* Encoding specific data */
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int enc_oldcode; /* last code encountered */
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long enc_checkpoint; /* point at which to clear table */
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#define CHECK_GAP 10000 /* enc_ratio check interval */
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long enc_ratio; /* current compression ratio */
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long enc_incount; /* (input) data bytes encoded */
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long enc_outcount; /* encoded (output) bytes */
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tidata_t enc_rawlimit; /* bound on tif_rawdata buffer */
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hash_t* enc_hashtab; /* kept separate for small machines */
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#define LZWState(tif) ((LZWBaseState*) (tif)->tif_data)
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#define DecoderState(tif) ((LZWCodecState*) LZWState(tif))
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#define EncoderState(tif) ((LZWCodecState*) LZWState(tif))
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static int LZWDecode(TIFF*, tidata_t, tsize_t, tsample_t);
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static int LZWDecodeCompat(TIFF*, tidata_t, tsize_t, tsample_t);
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static void cl_hash(LZWCodecState*);
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* This check shouldn't be necessary because each
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* strip is suppose to be terminated with CODE_EOI.
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#define NextCode(_tif, _sp, _bp, _code, _get) { \
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if ((_sp)->dec_bitsleft < nbits) { \
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TIFFWarningExt(_tif->tif_clientdata, _tif->tif_name, \
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"LZWDecode: Strip %d not terminated with EOI code", \
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_tif->tif_curstrip); \
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_get(_sp,_bp,_code); \
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(_sp)->dec_bitsleft -= nbits; \
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#define NextCode(tif, sp, bp, code, get) get(sp, bp, code)
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LZWSetupDecode(TIFF* tif)
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LZWCodecState* sp = DecoderState(tif);
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static const char module[] = " LZWSetupDecode";
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* Allocate state block so tag methods have storage to record
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tif->tif_data = (tidata_t) _TIFFmalloc(sizeof(LZWCodecState));
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if (tif->tif_data == NULL)
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TIFFErrorExt(tif->tif_clientdata, "LZWPreDecode", "No space for LZW state block");
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DecoderState(tif)->dec_codetab = NULL;
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DecoderState(tif)->dec_decode = NULL;
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* Setup predictor setup.
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(void) TIFFPredictorInit(tif);
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sp = DecoderState(tif);
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if (sp->dec_codetab == NULL) {
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sp->dec_codetab = (code_t*)_TIFFmalloc(CSIZE*sizeof (code_t));
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if (sp->dec_codetab == NULL) {
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TIFFErrorExt(tif->tif_clientdata, module,
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"No space for LZW code table");
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* Pre-load the table.
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sp->dec_codetab[code].value = code;
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sp->dec_codetab[code].firstchar = code;
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sp->dec_codetab[code].length = 1;
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sp->dec_codetab[code].next = NULL;
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* Zero-out the unused entries
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_TIFFmemset(&sp->dec_codetab[CODE_CLEAR], 0,
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(CODE_FIRST - CODE_CLEAR) * sizeof (code_t));
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* Setup state for decoding a strip.
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LZWPreDecode(TIFF* tif, tsample_t s)
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LZWCodecState *sp = DecoderState(tif);
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if( sp->dec_codetab == NULL )
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tif->tif_setupdecode( tif );
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* Check for old bit-reversed codes.
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if (tif->tif_rawdata[0] == 0 && (tif->tif_rawdata[1] & 0x1)) {
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if (!sp->dec_decode) {
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TIFFWarningExt(tif->tif_clientdata, tif->tif_name,
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"Old-style LZW codes, convert file");
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* Override default decoding methods with
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* ones that deal with the old coding.
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* Otherwise the predictor versions set
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* above will call the compatibility routines
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* through the dec_decode method.
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tif->tif_decoderow = LZWDecodeCompat;
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tif->tif_decodestrip = LZWDecodeCompat;
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tif->tif_decodetile = LZWDecodeCompat;
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* If doing horizontal differencing, must
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* re-setup the predictor logic since we
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* switched the basic decoder methods...
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(*tif->tif_setupdecode)(tif);
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sp->dec_decode = LZWDecodeCompat;
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sp->lzw_maxcode = MAXCODE(BITS_MIN);
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#else /* !LZW_COMPAT */
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if (!sp->dec_decode) {
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TIFFErrorExt(tif->tif_clientdata, tif->tif_name,
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"Old-style LZW codes not supported");
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sp->dec_decode = LZWDecode;
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#endif/* !LZW_COMPAT */
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sp->lzw_maxcode = MAXCODE(BITS_MIN)-1;
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sp->dec_decode = LZWDecode;
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sp->lzw_nbits = BITS_MIN;
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sp->lzw_nextbits = 0;
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sp->lzw_nextdata = 0;
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sp->dec_nbitsmask = MAXCODE(BITS_MIN);
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sp->dec_bitsleft = tif->tif_rawcc << 3;
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sp->dec_free_entp = sp->dec_codetab + CODE_FIRST;
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* Zero entries that are not yet filled in. We do
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* this to guard against bogus input data that causes
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* us to index into undefined entries. If you can
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* come up with a way to safely bounds-check input codes
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* while decoding then you can remove this operation.
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_TIFFmemset(sp->dec_free_entp, 0, (CSIZE-CODE_FIRST)*sizeof (code_t));
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sp->dec_oldcodep = &sp->dec_codetab[-1];
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sp->dec_maxcodep = &sp->dec_codetab[sp->dec_nbitsmask-1];
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* Decode a "hunk of data".
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#define GetNextCode(sp, bp, code) { \
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nextdata = (nextdata<<8) | *(bp)++; \
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if (nextbits < nbits) { \
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nextdata = (nextdata<<8) | *(bp)++; \
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code = (hcode_t)((nextdata >> (nextbits-nbits)) & nbitsmask); \
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TIFFErrorExt(tif->tif_clientdata, tif->tif_name,
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"LZWDecode: Bogus encoding, loop in the code table; scanline %d",
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LZWDecode(TIFF* tif, tidata_t op0, tsize_t occ0, tsample_t s)
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LZWCodecState *sp = DecoderState(tif);
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char *op = (char*) op0;
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long occ = (long) occ0;
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long nbits, nextbits, nextdata, nbitsmask;
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code_t *codep, *free_entp, *maxcodep, *oldcodep;
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assert(sp->dec_codetab != NULL);
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* Restart interrupted output operation.
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if (sp->dec_restart) {
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codep = sp->dec_codep;
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residue = codep->length - sp->dec_restart;
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* Residue from previous decode is sufficient
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* to satisfy decode request. Skip to the
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* start of the decoded string, place decoded
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* values in the output buffer, and return.
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sp->dec_restart += occ;
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} while (--residue > occ && codep);
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*--tp = codep->value;
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} while (--occ && codep);
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* Residue satisfies only part of the decode request.
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op += residue, occ -= residue;
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} while (--residue && codep);
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bp = (unsigned char *)tif->tif_rawcp;
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nbits = sp->lzw_nbits;
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nextdata = sp->lzw_nextdata;
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nextbits = sp->lzw_nextbits;
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nbitsmask = sp->dec_nbitsmask;
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oldcodep = sp->dec_oldcodep;
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free_entp = sp->dec_free_entp;
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maxcodep = sp->dec_maxcodep;
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NextCode(tif, sp, bp, code, GetNextCode);
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if (code == CODE_EOI)
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if (code == CODE_CLEAR) {
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free_entp = sp->dec_codetab + CODE_FIRST;
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_TIFFmemset(free_entp, 0,
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(CSIZE - CODE_FIRST) * sizeof (code_t));
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nbitsmask = MAXCODE(BITS_MIN);
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maxcodep = sp->dec_codetab + nbitsmask-1;
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NextCode(tif, sp, bp, code, GetNextCode);
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if (code == CODE_EOI)
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if (code == CODE_CLEAR) {
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TIFFErrorExt(tif->tif_clientdata, tif->tif_name,
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"LZWDecode: Corrupted LZW table at scanline %d",
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*op++ = (char)code, occ--;
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oldcodep = sp->dec_codetab + code;
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codep = sp->dec_codetab + code;
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* Add the new entry to the code table.
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if (free_entp < &sp->dec_codetab[0] ||
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free_entp >= &sp->dec_codetab[CSIZE]) {
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TIFFErrorExt(tif->tif_clientdata, tif->tif_name,
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"LZWDecode: Corrupted LZW table at scanline %d",
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free_entp->next = oldcodep;
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if (free_entp->next < &sp->dec_codetab[0] ||
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free_entp->next >= &sp->dec_codetab[CSIZE]) {
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TIFFErrorExt(tif->tif_clientdata, tif->tif_name,
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"LZWDecode: Corrupted LZW table at scanline %d",
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free_entp->firstchar = free_entp->next->firstchar;
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free_entp->length = free_entp->next->length+1;
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free_entp->value = (codep < free_entp) ?
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codep->firstchar : free_entp->firstchar;
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if (++free_entp > maxcodep) {
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if (++nbits > BITS_MAX) /* should not happen */
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nbitsmask = MAXCODE(nbits);
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maxcodep = sp->dec_codetab + nbitsmask-1;
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* Code maps to a string, copy string
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* value to output (written in reverse).
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if(codep->length == 0) {
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TIFFErrorExt(tif->tif_clientdata, tif->tif_name,
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"LZWDecode: Wrong length of decoded string: "
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"data probably corrupted at scanline %d",
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if (codep->length > occ) {
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* String is too long for decode buffer,
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* locate portion that will fit, copy to
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* the decode buffer, and setup restart
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* logic for the next decoding call.
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sp->dec_codep = codep;
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} while (codep && codep->length > occ);
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sp->dec_restart = occ;
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*--tp = codep->value;
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} while (--occ && codep);
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} while (codep && tp > op);
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op += len, occ -= len;
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*op++ = (char)code, occ--;
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tif->tif_rawcp = (tidata_t) bp;
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sp->lzw_nbits = (unsigned short) nbits;
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sp->lzw_nextdata = nextdata;
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sp->lzw_nextbits = nextbits;
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sp->dec_nbitsmask = nbitsmask;
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sp->dec_oldcodep = oldcodep;
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sp->dec_free_entp = free_entp;
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sp->dec_maxcodep = maxcodep;
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TIFFErrorExt(tif->tif_clientdata, tif->tif_name,
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"LZWDecode: Not enough data at scanline %d (short %ld bytes)",
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* Decode a "hunk of data" for old images.
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#define GetNextCodeCompat(sp, bp, code) { \
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nextdata |= (unsigned long) *(bp)++ << nextbits; \
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if (nextbits < nbits) { \
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nextdata |= (unsigned long) *(bp)++ << nextbits;\
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code = (hcode_t)(nextdata & nbitsmask); \
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nextdata >>= nbits; \
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LZWDecodeCompat(TIFF* tif, tidata_t op0, tsize_t occ0, tsample_t s)
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LZWCodecState *sp = DecoderState(tif);
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char *op = (char*) op0;
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long occ = (long) occ0;
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long nextbits, nextdata, nbitsmask;
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code_t *codep, *free_entp, *maxcodep, *oldcodep;
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* Restart interrupted output operation.
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if (sp->dec_restart) {
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codep = sp->dec_codep;
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residue = codep->length - sp->dec_restart;
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* Residue from previous decode is sufficient
585
* to satisfy decode request. Skip to the
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* start of the decoded string, place decoded
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* values in the output buffer, and return.
589
sp->dec_restart += occ;
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} while (--residue > occ);
595
*--tp = codep->value;
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* Residue satisfies only part of the decode request.
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op += residue, occ -= residue;
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*--tp = codep->value;
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bp = (unsigned char *)tif->tif_rawcp;
613
nbits = sp->lzw_nbits;
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nextdata = sp->lzw_nextdata;
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nextbits = sp->lzw_nextbits;
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nbitsmask = sp->dec_nbitsmask;
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oldcodep = sp->dec_oldcodep;
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free_entp = sp->dec_free_entp;
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maxcodep = sp->dec_maxcodep;
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NextCode(tif, sp, bp, code, GetNextCodeCompat);
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if (code == CODE_EOI)
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if (code == CODE_CLEAR) {
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free_entp = sp->dec_codetab + CODE_FIRST;
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_TIFFmemset(free_entp, 0,
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(CSIZE - CODE_FIRST) * sizeof (code_t));
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nbitsmask = MAXCODE(BITS_MIN);
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maxcodep = sp->dec_codetab + nbitsmask;
632
NextCode(tif, sp, bp, code, GetNextCodeCompat);
633
if (code == CODE_EOI)
635
if (code == CODE_CLEAR) {
636
TIFFErrorExt(tif->tif_clientdata, tif->tif_name,
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"LZWDecode: Corrupted LZW table at scanline %d",
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oldcodep = sp->dec_codetab + code;
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codep = sp->dec_codetab + code;
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* Add the new entry to the code table.
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if (free_entp < &sp->dec_codetab[0] ||
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free_entp >= &sp->dec_codetab[CSIZE]) {
652
TIFFErrorExt(tif->tif_clientdata, tif->tif_name,
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"LZWDecodeCompat: Corrupted LZW table at scanline %d",
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free_entp->next = oldcodep;
659
if (free_entp->next < &sp->dec_codetab[0] ||
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free_entp->next >= &sp->dec_codetab[CSIZE]) {
661
TIFFErrorExt(tif->tif_clientdata, tif->tif_name,
662
"LZWDecodeCompat: Corrupted LZW table at scanline %d",
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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 */
673
nbitsmask = MAXCODE(nbits);
674
maxcodep = sp->dec_codetab + nbitsmask;
680
* Code maps to a string, copy string
681
* value to output (written in reverse).
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",
690
if (codep->length > occ) {
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.
697
sp->dec_codep = codep;
700
} while (codep->length > occ);
701
sp->dec_restart = occ;
704
*--tp = codep->value;
709
op += codep->length, occ -= codep->length;
712
*--tp = codep->value;
713
} while( (codep = codep->next) != NULL && tp > op_orig);
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;
728
TIFFErrorExt(tif->tif_clientdata, tif->tif_name,
729
"LZWDecodeCompat: Not enough data at scanline %d (short %ld bytes)",
735
#endif /* LZW_COMPAT */
742
LZWSetupEncode(TIFF* tif)
744
LZWCodecState* sp = EncoderState(tif);
745
static const char module[] = "LZWSetupEncode";
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");
757
* Reset encoding state at the start of a strip.
760
LZWPreEncode(TIFF* tif, tsample_t s)
762
LZWCodecState *sp = EncoderState(tif);
767
if( sp->enc_hashtab == NULL )
769
tif->tif_setupencode( tif );
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;
780
sp->enc_outcount = 0;
782
* The 4 here insures there is space for 2 max-sized
783
* codes in LZWEncode and LZWPostDecode.
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 */
791
#define CALCRATIO(sp, rat) { \
792
if (incount > 0x007fffff) { /* NB: shift will overflow */\
793
rat = outcount >> 8; \
794
rat = (rat == 0 ? 0x7fffffff : incount/rat); \
796
rat = (incount<<8) / outcount; \
798
#define PutNextCode(op, c) { \
799
nextdata = (nextdata << nbits) | c; \
801
*op++ = (unsigned char)(nextdata >> (nextbits-8)); \
803
if (nextbits >= 8) { \
804
*op++ = (unsigned char)(nextdata >> (nextbits-8)); \
811
* Encode a chunk of pixels.
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
825
LZWEncode(TIFF* tif, tidata_t bp, tsize_t cc, tsample_t s)
827
register LZWCodecState *sp = EncoderState(tif);
833
long incount, outcount, checkpoint;
834
long nextdata, nextbits;
835
int free_ent, maxcode, nbits;
842
assert(sp->enc_hashtab != NULL);
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;
856
limit = sp->enc_rawlimit;
857
ent = sp->enc_oldcode;
859
if (ent == (hcode_t) -1 && cc > 0) {
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.
865
PutNextCode(op, CODE_CLEAR);
866
ent = *bp++; cc--; incount++;
869
c = *bp++; cc--; incount++;
870
fcode = ((long)c << BITS_MAX) + ent;
871
h = (c << HSHIFT) ^ ent; /* xor hashing */
874
* Check hash index for an overflow.
879
hp = &sp->enc_hashtab[h];
880
if (hp->hash == fcode) {
886
* Primary hash failed, check secondary hash.
893
* Avoid pointer arithmetic 'cuz of
894
* wraparound problems with segments.
898
hp = &sp->enc_hashtab[h];
899
if (hp->hash == fcode) {
903
} while (hp->hash >= 0);
906
* New entry, emit code and add to table.
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.
915
tif->tif_rawcc = (tsize_t)(op - tif->tif_rawdata);
917
op = tif->tif_rawdata;
919
PutNextCode(op, ent);
921
hp->code = free_ent++;
923
if (free_ent == CODE_MAX-1) {
924
/* table is full, emit clear code and reset */
929
free_ent = CODE_FIRST;
930
PutNextCode(op, CODE_CLEAR);
932
maxcode = MAXCODE(BITS_MIN);
935
* If the next entry is going to be too big for
936
* the code size, then increase it, if possible.
938
if (free_ent > maxcode) {
940
assert(nbits <= BITS_MAX);
941
maxcode = (int) MAXCODE(nbits);
942
} else if (incount >= checkpoint) {
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.
950
checkpoint = incount+CHECK_GAP;
952
if (rat <= sp->enc_ratio) {
957
free_ent = CODE_FIRST;
958
PutNextCode(op, CODE_CLEAR);
960
maxcode = MAXCODE(BITS_MIN);
970
* Restore global state.
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;
986
* Finish off an encoded strip by flushing the last
987
* string and tacking on an End Of Information code.
990
LZWPostEncode(TIFF* tif)
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;
999
if (op > sp->enc_rawlimit) {
1000
tif->tif_rawcc = (tsize_t)(op - tif->tif_rawdata);
1001
TIFFFlushData1(tif);
1002
op = tif->tif_rawdata;
1004
if (sp->enc_oldcode != (hcode_t) -1) {
1005
PutNextCode(op, sp->enc_oldcode);
1006
sp->enc_oldcode = (hcode_t) -1;
1008
PutNextCode(op, CODE_EOI);
1010
*op++ = (unsigned char)(nextdata << (8-nextbits));
1011
tif->tif_rawcc = (tsize_t)(op - tif->tif_rawdata);
1016
* Reset encoding hash table.
1019
cl_hash(LZWCodecState* sp)
1021
register hash_t *hp = &sp->enc_hashtab[HSIZE-1];
1022
register long i = HSIZE-8;
1036
for (i += 8; i > 0; i--, hp--)
1041
LZWCleanup(TIFF* tif)
1043
(void)TIFFPredictorCleanup(tif);
1045
assert(tif->tif_data != 0);
1047
if (DecoderState(tif)->dec_codetab)
1048
_TIFFfree(DecoderState(tif)->dec_codetab);
1050
if (EncoderState(tif)->enc_hashtab)
1051
_TIFFfree(EncoderState(tif)->enc_hashtab);
1053
_TIFFfree(tif->tif_data);
1054
tif->tif_data = NULL;
1056
_TIFFSetDefaultCompressionState(tif);
1060
TIFFInitLZW(TIFF* tif, int scheme)
1062
assert(scheme == COMPRESSION_LZW);
1064
* Allocate state block so tag methods have storage to record values.
1066
tif->tif_data = (tidata_t) _TIFFmalloc(sizeof (LZWCodecState));
1067
if (tif->tif_data == NULL)
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;
1075
* Install codec methods.
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;
1090
* Setup predictor setup.
1092
(void) TIFFPredictorInit(tif);
1095
TIFFErrorExt(tif->tif_clientdata, "TIFFInitLZW",
1096
"No space for LZW state block");
1101
* Copyright (c) 1985, 1986 The Regents of the University of California.
1102
* All rights reserved.
1104
* This code is derived from software contributed to Berkeley by
1105
* James A. Woods, derived from original work by Spencer Thomas
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.
1120
#endif /* LZW_SUPPORT */
1122
/* vim: set ts=8 sts=8 sw=8 noet: */
added
removed
libtiff/tif_lzw.c
