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tif_lzw.c@ 287

Last change on this file since 287 was 95, checked in by Rick van der Zwet, 15 years ago
Bad boy, improper move of directory
File size: 28.8 KB

Rev	Line
[95]	1	/* $Id: tif_lzw.c,v 1.28 2006/03/16 12:38:24 dron 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(CSIZEsizeof (code_t));
	226	if (sp->dec_codetab == NULL) {
	227	TIFFErrorExt(tif->tif_clientdata, 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	TIFFWarningExt(tif->tif_clientdata, 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	TIFFErrorExt(tif->tif_clientdata, 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	TIFFErrorExt(tif->tif_clientdata, 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	TIFFErrorExt(tif->tif_clientdata, 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	TIFFErrorExt(tif->tif_clientdata, 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	TIFFErrorExt(tif->tif_clientdata, 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	TIFFErrorExt(tif->tif_clientdata, 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	TIFFErrorExt(tif->tif_clientdata, 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	TIFFErrorExt(tif->tif_clientdata, 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	TIFFErrorExt(tif->tif_clientdata, 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	TIFFErrorExt(tif->tif_clientdata, 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(HSIZEsizeof (hash_t));
	720	if (sp->enc_hashtab == NULL) {
	721	TIFFErrorExt(tif->tif_clientdata, 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	(void)TIFFPredictorCleanup(tif);
	1006
	1007	assert(tif->tif_data != 0);
	1008
	1009	if (DecoderState(tif)->dec_codetab)
	1010	_TIFFfree(DecoderState(tif)->dec_codetab);
	1011
	1012	if (EncoderState(tif)->enc_hashtab)
	1013	_TIFFfree(EncoderState(tif)->enc_hashtab);
	1014
	1015	_TIFFfree(tif->tif_data);
	1016	tif->tif_data = NULL;
	1017
	1018	_TIFFSetDefaultCompressionState(tif);
	1019	}
	1020
	1021	int
	1022	TIFFInitLZW(TIFF* tif, int scheme)
	1023	{
	1024	assert(scheme == COMPRESSION_LZW);
	1025	/*
	1026	* Allocate state block so tag methods have storage to record values.
	1027	*/
	1028	tif->tif_data = (tidata_t) _TIFFmalloc(sizeof (LZWCodecState));
	1029	if (tif->tif_data == NULL)
	1030	goto bad;
	1031	DecoderState(tif)->dec_codetab = NULL;
	1032	DecoderState(tif)->dec_decode = NULL;
	1033	EncoderState(tif)->enc_hashtab = NULL;
	1034	LZWState(tif)->rw_mode = tif->tif_mode;
	1035
	1036	/*
	1037	* Install codec methods.
	1038	*/
	1039	tif->tif_setupdecode = LZWSetupDecode;
	1040	tif->tif_predecode = LZWPreDecode;
	1041	tif->tif_decoderow = LZWDecode;
	1042	tif->tif_decodestrip = LZWDecode;
	1043	tif->tif_decodetile = LZWDecode;
	1044	tif->tif_setupencode = LZWSetupEncode;
	1045	tif->tif_preencode = LZWPreEncode;
	1046	tif->tif_postencode = LZWPostEncode;
	1047	tif->tif_encoderow = LZWEncode;
	1048	tif->tif_encodestrip = LZWEncode;
	1049	tif->tif_encodetile = LZWEncode;
	1050	tif->tif_cleanup = LZWCleanup;
	1051	/*
	1052	* Setup predictor setup.
	1053	*/
	1054	(void) TIFFPredictorInit(tif);
	1055	return (1);
	1056	bad:
	1057	TIFFErrorExt(tif->tif_clientdata, "TIFFInitLZW",
	1058	"No space for LZW state block");
	1059	return (0);
	1060	}
	1061
	1062	/*
	1063	* Copyright (c) 1985, 1986 The Regents of the University of California.
	1064	* All rights reserved.
	1065	*
	1066	* This code is derived from software contributed to Berkeley by
	1067	* James A. Woods, derived from original work by Spencer Thomas
	1068	* and Joseph Orost.
	1069	*
	1070	* Redistribution and use in source and binary forms are permitted
	1071	* provided that the above copyright notice and this paragraph are
	1072	* duplicated in all such forms and that any documentation,
	1073	* advertising materials, and other materials related to such
	1074	* distribution and use acknowledge that the software was developed
	1075	* by the University of California, Berkeley. The name of the
	1076	* University may not be used to endorse or promote products derived
	1077	* from this software without specific prior written permission.
	1078	* THIS SOFTWARE IS PROVIDED ``AS IS'' AND WITHOUT ANY EXPRESS OR
	1079	* IMPLIED WARRANTIES, INCLUDING, WITHOUT LIMITATION, THE IMPLIED
	1080	* WARRANTIES OF MERCHANTIBILITY AND FITNESS FOR A PARTICULAR PURPOSE.
	1081	*/
	1082	#endif /* LZW_SUPPORT */
	1083
	1084	/* vim: set ts=8 sts=8 sw=8 noet: */

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