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1	// DeflaterEngine.cs
2	//
3	// Copyright (C) 2001 Mike Krueger
4	// Copyright (C) 2004 John Reilly
5	//
6	// This file was translated from java, it was part of the GNU Classpath
7	// Copyright (C) 2001 Free Software Foundation, Inc.
8	//
9	// This program is free software; you can redistribute it and/or
10	// modify it under the terms of the GNU General Public License
11	// as published by the Free Software Foundation; either version 2
12	// of the License, or (at your option) any later version.
13	//
14	// This program is distributed in the hope that it will be useful,
15	// but WITHOUT ANY WARRANTY; without even the implied warranty of
16	// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
17	// GNU General Public License for more details.
18	//
19	// You should have received a copy of the GNU General Public License
20	// along with this program; if not, write to the Free Software
21	// Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
22	//
23	// Linking this library statically or dynamically with other modules is
24	// making a combined work based on this library. Thus, the terms and
25	// conditions of the GNU General Public License cover the whole
26	// combination.
27	//
28	// As a special exception, the copyright holders of this library give you
29	// permission to link this library with independent modules to produce an
30	// executable, regardless of the license terms of these independent
31	// modules, and to copy and distribute the resulting executable under
32	// terms of your choice, provided that you also meet, for each linked
33	// independent module, the terms and conditions of the license of that
34	// module. An independent module is a module which is not derived from
35	// or based on this library. If you modify this library, you may extend
36	// this exception to your version of the library, but you are not
37	// obligated to do so. If you do not wish to do so, delete this
38	// exception statement from your version.
39
40	using System;
41
42	using ICSharpCode.SharpZipLib.Checksums;
43
44	namespace ICSharpCode.SharpZipLib.Zip.Compression
45	{
46
47	/// <summary>
48	/// Strategies for deflater
49	/// </summary>
50	public enum DeflateStrategy
51	{
52	/// <summary>
53	/// The default strategy
54	/// </summary>
55	Default = 0,
56
57	/// <summary>
58	/// This strategy will only allow longer string repetitions. It is
59	/// useful for random data with a small character set.
60	/// </summary>
61	Filtered = 1,
62
63
64	/// <summary>
65	/// This strategy will not look for string repetitions at all. It
66	/// only encodes with Huffman trees (which means, that more common
67	/// characters get a smaller encoding.
68	/// </summary>
69	HuffmanOnly = 2
70	}
71
72	// DEFLATE ALGORITHM:
73	//
74	// The uncompressed stream is inserted into the window array. When
75	// the window array is full the first half is thrown away and the
76	// second half is copied to the beginning.
77	//
78	// The head array is a hash table. Three characters build a hash value
79	// and they the value points to the corresponding index in window of
80	// the last string with this hash. The prev array implements a
81	// linked list of matches with the same hash: prev[index & WMASK] points
82	// to the previous index with the same hash.
83	//
84
85
86	/// <summary>
87	/// Low level compression engine for deflate algorithm which uses a 32K sliding window
88	/// with secondary compression from Huffman/Shannon-Fano codes.
89	/// </summary>
90	public class DeflaterEngine : DeflaterConstants
91	{
92	#region Constants
93	const int TooFar = 4096;
94	#endregion
95
96	#region Constructors
97	/// <summary>
98	/// Construct instance with pending buffer
99	/// </summary>
100	/// <param name="pending">
101	/// Pending buffer to use
102	/// </param>>
103	public DeflaterEngine(DeflaterPending pending)
104	{
105	this.pending = pending;
106	huffman = new DeflaterHuffman(pending);
107	adler = new Adler32();
108
109	window = new byte[2 * WSIZE];
110	head = new short[HASH_SIZE];
111	prev = new short[WSIZE];
112
113	// We start at index 1, to avoid an implementation deficiency, that
114	// we cannot build a repeat pattern at index 0.
115	blockStart = strstart = 1;
116	}
117
118	#endregion
119
120	/// <summary>
121	/// Deflate drives actual compression of data
122	/// </summary>
123	/// <param name="flush">True to flush input buffers</param>
124	/// <param name="finish">Finish deflation with the current input.</param>
125	/// <returns>Returns true if progress has been made.</returns>
126	public bool Deflate(bool flush, bool finish)
127	{
128	bool progress;
129	do
130	{
131	FillWindow();
132	bool canFlush = flush && (inputOff == inputEnd);
133
134	#if DebugDeflation
135	if (DeflaterConstants.DEBUGGING) {
136	Console.WriteLine("window: [" + blockStart + "," + strstart + ","
137	+ lookahead + "], " + compressionFunction + "," + canFlush);
138	}
139	#endif
140	switch (compressionFunction)
141	{
142	case DEFLATE_STORED:
143	progress = DeflateStored(canFlush, finish);
144	break;
145	case DEFLATE_FAST:
146	progress = DeflateFast(canFlush, finish);
147	break;
148	case DEFLATE_SLOW:
149	progress = DeflateSlow(canFlush, finish);
150	break;
151	default:
152	throw new InvalidOperationException("unknown compressionFunction");
153	}
154	} while (pending.IsFlushed && progress); // repeat while we have no pending output and progress was made
155	return progress;
156	}
157
158	/// <summary>
159	/// Sets input data to be deflated. Should only be called when <code>NeedsInput()</code>
160	/// returns true
161	/// </summary>
162	/// <param name="buffer">The buffer containing input data.</param>
163	/// <param name="offset">The offset of the first byte of data.</param>
164	/// <param name="count">The number of bytes of data to use as input.</param>
165	public void SetInput(byte[] buffer, int offset, int count)
166	{
167	if ( buffer == null )
168	{
169	throw new ArgumentNullException("buffer");
170	}
171
172	if ( offset < 0 )
173	{
174	throw new ArgumentOutOfRangeException("offset");
175	}
176
177	if ( count < 0 )
178	{
179	throw new ArgumentOutOfRangeException("count");
180	}
181
182	if (inputOff < inputEnd)
183	{
184	throw new InvalidOperationException("Old input was not completely processed");
185	}
186
187	int end = offset + count;
188
189	/* We want to throw an ArrayIndexOutOfBoundsException early. The
190	* check is very tricky: it also handles integer wrap around.
191	*/
192	if ((offset > end) \|\| (end > buffer.Length) )
193	{
194	throw new ArgumentOutOfRangeException("count");
195	}
196
197	inputBuf = buffer;
198	inputOff = offset;
199	inputEnd = end;
200	}
201
202	/// <summary>
203	/// Determines if more <see cref="SetInput">input</see> is needed.
204	/// </summary>
205	/// <returns>Return true if input is needed via <see cref="SetInput">SetInput</see></returns>
206	public bool NeedsInput()
207	{
208	return (inputEnd == inputOff);
209	}
210
211	/// <summary>
212	/// Set compression dictionary
213	/// </summary>
214	/// <param name="buffer">The buffer containing the dictionary data</param>
215	/// <param name="offset">The offset in the buffer for the first byte of data</param>
216	/// <param name="length">The length of the dictionary data.</param>
217	public void SetDictionary(byte[] buffer, int offset, int length)
218	{
219	#if DebugDeflation
220	if (DeflaterConstants.DEBUGGING && (strstart != 1) )
221	{
222	throw new InvalidOperationException("strstart not 1");
223	}
224	#endif
225	adler.Update(buffer, offset, length);
226	if (length < MIN_MATCH)
227	{
228	return;
229	}
230
231	if (length > MAX_DIST)
232	{
233	offset += length - MAX_DIST;
234	length = MAX_DIST;
235	}
236
237	System.Array.Copy(buffer, offset, window, strstart, length);
238
239	UpdateHash();
240	--length;
241	while (--length > 0)
242	{
243	InsertString();
244	strstart++;
245	}
246	strstart += 2;
247	blockStart = strstart;
248	}
249
250	/// <summary>
251	/// Reset internal state
252	/// </summary>
253	public void Reset()
254	{
255	huffman.Reset();
256	adler.Reset();
257	blockStart = strstart = 1;
258	lookahead = 0;
259	totalIn = 0;
260	prevAvailable = false;
261	matchLen = MIN_MATCH - 1;
262
263	for (int i = 0; i < HASH_SIZE; i++) {
264	head[i] = 0;
265	}
266
267	for (int i = 0; i < WSIZE; i++) {
268	prev[i] = 0;
269	}
270	}
271
272	/// <summary>
273	/// Reset Adler checksum
274	/// </summary>
275	public void ResetAdler()
276	{
277	adler.Reset();
278	}
279
280	/// <summary>
281	/// Get current value of Adler checksum
282	/// </summary>
283	public int Adler {
284	get {
285	return unchecked((int)adler.Value);
286	}
287	}
288
289	/// <summary>
290	/// Total data processed
291	/// </summary>
292	public long TotalIn {
293	get {
294	return totalIn;
295	}
296	}
297
298	/// <summary>
299	/// Get/set the <see cref="DeflateStrategy">deflate strategy</see>
300	/// </summary>
301	public DeflateStrategy Strategy {
302	get {
303	return strategy;
304	}
305	set {
306	strategy = value;
307	}
308	}
309
310	/// <summary>
311	/// Set the deflate level (0-9)
312	/// </summary>
313	/// <param name="level">The value to set the level to.</param>
314	public void SetLevel(int level)
315	{
316	if ( (level < 0) \|\| (level > 9) )
317	{
318	throw new ArgumentOutOfRangeException("level");
319	}
320
321	goodLength = DeflaterConstants.GOOD_LENGTH[level];
322	max_lazy = DeflaterConstants.MAX_LAZY[level];
323	niceLength = DeflaterConstants.NICE_LENGTH[level];
324	max_chain = DeflaterConstants.MAX_CHAIN[level];
325
326	if (DeflaterConstants.COMPR_FUNC[level] != compressionFunction) {
327
328	#if DebugDeflation
329	if (DeflaterConstants.DEBUGGING) {
330	Console.WriteLine("Change from " + compressionFunction + " to "
331	+ DeflaterConstants.COMPR_FUNC[level]);
332	}
333	#endif
334	switch (compressionFunction) {
335	case DEFLATE_STORED:
336	if (strstart > blockStart) {
337	huffman.FlushStoredBlock(window, blockStart,
338	strstart - blockStart, false);
339	blockStart = strstart;
340	}
341	UpdateHash();
342	break;
343
344	case DEFLATE_FAST:
345	if (strstart > blockStart) {
346	huffman.FlushBlock(window, blockStart, strstart - blockStart,
347	false);
348	blockStart = strstart;
349	}
350	break;
351
352	case DEFLATE_SLOW:
353	if (prevAvailable) {
354	huffman.TallyLit(window[strstart-1] & 0xff);
355	}
356	if (strstart > blockStart) {
357	huffman.FlushBlock(window, blockStart, strstart - blockStart, false);
358	blockStart = strstart;
359	}
360	prevAvailable = false;
361	matchLen = MIN_MATCH - 1;
362	break;
363	}
364	compressionFunction = COMPR_FUNC[level];
365	}
366	}
367
368	/// <summary>
369	/// Fill the window
370	/// </summary>
371	public void FillWindow()
372	{
373	/* If the window is almost full and there is insufficient lookahead,
374	* move the upper half to the lower one to make room in the upper half.
375	*/
376	if (strstart >= WSIZE + MAX_DIST)
377	{
378	SlideWindow();
379	}
380
381	/* If there is not enough lookahead, but still some input left,
382	* read in the input
383	*/
384	while (lookahead < DeflaterConstants.MIN_LOOKAHEAD && inputOff < inputEnd)
385	{
386	int more = 2 * WSIZE - lookahead - strstart;
387
388	if (more > inputEnd - inputOff)
389	{
390	more = inputEnd - inputOff;
391	}
392
393	System.Array.Copy(inputBuf, inputOff, window, strstart + lookahead, more);
394	adler.Update(inputBuf, inputOff, more);
395
396	inputOff += more;
397	totalIn += more;
398	lookahead += more;
399	}
400
401	if (lookahead >= MIN_MATCH)
402	{
403	UpdateHash();
404	}
405	}
406
407	void UpdateHash()
408	{
409	/*
410	if (DEBUGGING) {
411	Console.WriteLine("updateHash: "+strstart);
412	}
413	*/
414	ins_h = (window[strstart] << HASH_SHIFT) ^ window[strstart + 1];
415	}
416
417	/// <summary>
418	/// Inserts the current string in the head hash and returns the previous
419	/// value for this hash.
420	/// </summary>
421	/// <returns>The previous hash value</returns>
422	int InsertString()
423	{
424	short match;
425	int hash = ((ins_h << HASH_SHIFT) ^ window[strstart + (MIN_MATCH -1)]) & HASH_MASK;
426
427	#if DebugDeflation
428	if (DeflaterConstants.DEBUGGING)
429	{
430	if (hash != (((window[strstart] << (2*HASH_SHIFT)) ^
431	(window[strstart + 1] << HASH_SHIFT) ^
432	(window[strstart + 2])) & HASH_MASK)) {
433	throw new SharpZipBaseException("hash inconsistent: " + hash + "/"
434	+window[strstart] + ","
435	+window[strstart + 1] + ","
436	+window[strstart + 2] + "," + HASH_SHIFT);
437	}
438	}
439	#endif
440	prev[strstart & WMASK] = match = head[hash];
441	head[hash] = unchecked((short)strstart);
442	ins_h = hash;
443	return match & 0xffff;
444	}
445
446	void SlideWindow()
447	{
448	Array.Copy(window, WSIZE, window, 0, WSIZE);
449	matchStart -= WSIZE;
450	strstart -= WSIZE;
451	blockStart -= WSIZE;
452
453	// Slide the hash table (could be avoided with 32 bit values
454	// at the expense of memory usage).
455	for (int i = 0; i < HASH_SIZE; ++i) {
456	int m = head[i] & 0xffff;
457	head[i] = (short)(m >= WSIZE ? (m - WSIZE) : 0);
458	}
459
460	// Slide the prev table.
461	for (int i = 0; i < WSIZE; i++) {
462	int m = prev[i] & 0xffff;
463	prev[i] = (short)(m >= WSIZE ? (m - WSIZE) : 0);
464	}
465	}
466
467	/// <summary>
468	/// Find the best (longest) string in the window matching the
469	/// string starting at strstart.
470	///
471	/// Preconditions:
472	/// <code>
473	/// strstart + MAX_MATCH <= window.length.</code>
474	/// </summary>
475	/// <param name="curMatch"></param>
476	/// <returns>True if a match greater than the minimum length is found</returns>
477	bool FindLongestMatch(int curMatch)
478	{
479	int chainLength = this.max_chain;
480	int niceLength = this.niceLength;
481	short[] prev = this.prev;
482	int scan = this.strstart;
483	int match;
484	int best_end = this.strstart + matchLen;
485	int best_len = Math.Max(matchLen, MIN_MATCH - 1);
486
487	int limit = Math.Max(strstart - MAX_DIST, 0);
488
489	int strend = strstart + MAX_MATCH - 1;
490	byte scan_end1 = window[best_end - 1];
491	byte scan_end = window[best_end];
492
493	// Do not waste too much time if we already have a good match:
494	if (best_len >= this.goodLength) {
495	chainLength >>= 2;
496	}
497
498	/* Do not look for matches beyond the end of the input. This is necessary
499	* to make deflate deterministic.
500	*/
501	if (niceLength > lookahead) {
502	niceLength = lookahead;
503	}
504
505	#if DebugDeflation
506
507	if (DeflaterConstants.DEBUGGING && (strstart > 2 * WSIZE - MIN_LOOKAHEAD))
508	{
509	throw new InvalidOperationException("need lookahead");
510	}
511	#endif
512
513	do {
514
515	#if DebugDeflation
516
517	if (DeflaterConstants.DEBUGGING && (curMatch >= strstart) )
518	{
519	throw new InvalidOperationException("no future");
520	}
521	#endif
522	if (window[curMatch + best_len] != scan_end \|\|
523	window[curMatch + best_len - 1] != scan_end1 \|\|
524	window[curMatch] != window[scan] \|\|
525	window[curMatch + 1] != window[scan + 1]) {
526	continue;
527	}
528
529	match = curMatch + 2;
530	scan += 2;
531
532	/* We check for insufficient lookahead only every 8th comparison;
533	* the 256th check will be made at strstart + 258.
534	*/
535	while (
536	window[++scan] == window[++match] &&
537	window[++scan] == window[++match] &&
538	window[++scan] == window[++match] &&
539	window[++scan] == window[++match] &&
540	window[++scan] == window[++match] &&
541	window[++scan] == window[++match] &&
542	window[++scan] == window[++match] &&
543	window[++scan] == window[++match] &&
544	(scan < strend))
545	{
546	// Do nothing
547	}
548
549	if (scan > best_end) {
550	#if DebugDeflation
551	if (DeflaterConstants.DEBUGGING && (ins_h == 0) )
552	Console.Error.WriteLine("Found match: " + curMatch + "-" + (scan - strstart));
553	#endif
554	matchStart = curMatch;
555	best_end = scan;
556	best_len = scan - strstart;
557
558	if (best_len >= niceLength) {
559	break;
560	}
561
562	scan_end1 = window[best_end - 1];
563	scan_end = window[best_end];
564	}
565	scan = strstart;
566	} while ((curMatch = (prev[curMatch & WMASK] & 0xffff)) > limit && --chainLength != 0);
567
568	matchLen = Math.Min(best_len, lookahead);
569	return matchLen >= MIN_MATCH;
570	}
571
572	bool DeflateStored(bool flush, bool finish)
573	{
574	if (!flush && (lookahead == 0)) {
575	return false;
576	}
577
578	strstart += lookahead;
579	lookahead = 0;
580
581	int storedLength = strstart - blockStart;
582
583	if ((storedLength >= DeflaterConstants.MAX_BLOCK_SIZE) \|\| // Block is full
584	(blockStart < WSIZE && storedLength >= MAX_DIST) \|\| // Block may move out of window
585	flush) {
586	bool lastBlock = finish;
587	if (storedLength > DeflaterConstants.MAX_BLOCK_SIZE) {
588	storedLength = DeflaterConstants.MAX_BLOCK_SIZE;
589	lastBlock = false;
590	}
591
592	#if DebugDeflation
593	if (DeflaterConstants.DEBUGGING)
594	{
595	Console.WriteLine("storedBlock[" + storedLength + "," + lastBlock + "]");
596	}
597	#endif
598
599	huffman.FlushStoredBlock(window, blockStart, storedLength, lastBlock);
600	blockStart += storedLength;
601	return !lastBlock;
602	}
603	return true;
604	}
605
606	bool DeflateFast(bool flush, bool finish)
607	{
608	if (lookahead < MIN_LOOKAHEAD && !flush) {
609	return false;
610	}
611
612	while (lookahead >= MIN_LOOKAHEAD \|\| flush) {
613	if (lookahead == 0) {
614	// We are flushing everything
615	huffman.FlushBlock(window, blockStart, strstart - blockStart, finish);
616	blockStart = strstart;
617	return false;
618	}
619
620	if (strstart > 2 * WSIZE - MIN_LOOKAHEAD) {
621	/* slide window, as FindLongestMatch needs this.
622	* This should only happen when flushing and the window
623	* is almost full.
624	*/
625	SlideWindow();
626	}
627
628	int hashHead;
629	if (lookahead >= MIN_MATCH &&
630	(hashHead = InsertString()) != 0 &&
631	strategy != DeflateStrategy.HuffmanOnly &&
632	strstart - hashHead <= MAX_DIST &&
633	FindLongestMatch(hashHead)) {
634	// longestMatch sets matchStart and matchLen
635	#if DebugDeflation
636	if (DeflaterConstants.DEBUGGING)
637	{
638	for (int i = 0 ; i < matchLen; i++) {
639	if (window[strstart + i] != window[matchStart + i]) {
640	throw new SharpZipBaseException("Match failure");
641	}
642	}
643	}
644	#endif
645
646	bool full = huffman.TallyDist(strstart - matchStart, matchLen);
647
648	lookahead -= matchLen;
649	if (matchLen <= max_lazy && lookahead >= MIN_MATCH) {
650	while (--matchLen > 0) {
651	++strstart;
652	InsertString();
653	}
654	++strstart;
655	} else {
656	strstart += matchLen;
657	if (lookahead >= MIN_MATCH - 1) {
658	UpdateHash();
659	}
660	}
661	matchLen = MIN_MATCH - 1;
662	if (!full) {
663	continue;
664	}
665	} else {
666	// No match found
667	huffman.TallyLit(window[strstart] & 0xff);
668	++strstart;
669	--lookahead;
670	}
671
672	if (huffman.IsFull()) {
673	bool lastBlock = finish && (lookahead == 0);
674	huffman.FlushBlock(window, blockStart, strstart - blockStart, lastBlock);
675	blockStart = strstart;
676	return !lastBlock;
677	}
678	}
679	return true;
680	}
681
682	bool DeflateSlow(bool flush, bool finish)
683	{
684	if (lookahead < MIN_LOOKAHEAD && !flush) {
685	return false;
686	}
687
688	while (lookahead >= MIN_LOOKAHEAD \|\| flush) {
689	if (lookahead == 0) {
690	if (prevAvailable) {
691	huffman.TallyLit(window[strstart-1] & 0xff);
692	}
693	prevAvailable = false;
694
695	// We are flushing everything
696	#if DebugDeflation
697	if (DeflaterConstants.DEBUGGING && !flush)
698	{
699	throw new SharpZipBaseException("Not flushing, but no lookahead");
700	}
701	#endif
702	huffman.FlushBlock(window, blockStart, strstart - blockStart,
703	finish);
704	blockStart = strstart;
705	return false;
706	}
707
708	if (strstart >= 2 * WSIZE - MIN_LOOKAHEAD) {
709	/* slide window, as FindLongestMatch needs this.
710	* This should only happen when flushing and the window
711	* is almost full.
712	*/
713	SlideWindow();
714	}
715
716	int prevMatch = matchStart;
717	int prevLen = matchLen;
718	if (lookahead >= MIN_MATCH) {
719
720	int hashHead = InsertString();
721
722	if (strategy != DeflateStrategy.HuffmanOnly &&
723	hashHead != 0 &&
724	strstart - hashHead <= MAX_DIST &&
725	FindLongestMatch(hashHead)) {
726
727	// longestMatch sets matchStart and matchLen
728
729	// Discard match if too small and too far away
730	if (matchLen <= 5 && (strategy == DeflateStrategy.Filtered \|\| (matchLen == MIN_MATCH && strstart - matchStart > TooFar))) {
731	matchLen = MIN_MATCH - 1;
732	}
733	}
734	}
735
736	// previous match was better
737	if ((prevLen >= MIN_MATCH) && (matchLen <= prevLen) ) {
738	#if DebugDeflation
739	if (DeflaterConstants.DEBUGGING)
740	{
741	for (int i = 0 ; i < matchLen; i++) {
742	if (window[strstart-1+i] != window[prevMatch + i])
743	throw new SharpZipBaseException();
744	}
745	}
746	#endif
747	huffman.TallyDist(strstart - 1 - prevMatch, prevLen);
748	prevLen -= 2;
749	do {
750	strstart++;
751	lookahead--;
752	if (lookahead >= MIN_MATCH) {
753	InsertString();
754	}
755	} while (--prevLen > 0);
756
757	strstart ++;
758	lookahead--;
759	prevAvailable = false;
760	matchLen = MIN_MATCH - 1;
761	} else {
762	if (prevAvailable) {
763	huffman.TallyLit(window[strstart-1] & 0xff);
764	}
765	prevAvailable = true;
766	strstart++;
767	lookahead--;
768	}
769
770	if (huffman.IsFull()) {
771	int len = strstart - blockStart;
772	if (prevAvailable) {
773	len--;
774	}
775	bool lastBlock = (finish && (lookahead == 0) && !prevAvailable);
776	huffman.FlushBlock(window, blockStart, len, lastBlock);
777	blockStart += len;
778	return !lastBlock;
779	}
780	}
781	return true;
782	}
783
784	#region Instance Fields
785
786	// Hash index of string to be inserted
787	int ins_h;
788
789	/// <summary>
790	/// Hashtable, hashing three characters to an index for window, so
791	/// that window[index]..window[index+2] have this hash code.
792	/// Note that the array should really be unsigned short, so you need
793	/// to and the values with 0xffff.
794	/// </summary>
795	short[] head;
796
797	/// <summary>
798	/// <code>prev[index & WMASK]</code> points to the previous index that has the
799	/// same hash code as the string starting at index. This way
800	/// entries with the same hash code are in a linked list.
801	/// Note that the array should really be unsigned short, so you need
802	/// to and the values with 0xffff.
803	/// </summary>
804	short[] prev;
805
806	int matchStart;
807	// Length of best match
808	int matchLen;
809	// Set if previous match exists
810	bool prevAvailable;
811	int blockStart;
812
813	/// <summary>
814	/// Points to the current character in the window.
815	/// </summary>
816	int strstart;
817
818	/// <summary>
819	/// lookahead is the number of characters starting at strstart in
820	/// window that are valid.
821	/// So window[strstart] until window[strstart+lookahead-1] are valid
822	/// characters.
823	/// </summary>
824	int lookahead;
825
826	/// <summary>
827	/// This array contains the part of the uncompressed stream that
828	/// is of relevance. The current character is indexed by strstart.
829	/// </summary>
830	byte[] window;
831
832	DeflateStrategy strategy;
833	int max_chain, max_lazy, niceLength, goodLength;
834
835	/// <summary>
836	/// The current compression function.
837	/// </summary>
838	int compressionFunction;
839
840	/// <summary>
841	/// The input data for compression.
842	/// </summary>
843	byte[] inputBuf;
844
845	/// <summary>
846	/// The total bytes of input read.
847	/// </summary>
848	long totalIn;
849
850	/// <summary>
851	/// The offset into inputBuf, where input data starts.
852	/// </summary>
853	int inputOff;
854
855	/// <summary>
856	/// The end offset of the input data.
857	/// </summary>
858	int inputEnd;
859
860	DeflaterPending pending;
861	DeflaterHuffman huffman;
862
863	/// <summary>
864	/// The adler checksum
865	/// </summary>
866	Adler32 adler;
867	#endregion
868	}
869	}

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