| 123456789101112131415161718192021222324252627282930313233343536373839404142434445464748495051525354555657585960616263646566676869707172737475767778798081828384858687888990919293949596979899100101102103104105106107108109110111112113114115116117118119120121122123124125126127128129130131132133134135136137138139140141142143144145146147148149150151152153154155156157158159160161162163164165166167168169170171172173174175176177178179180181182183184185186187188189190191192193194195196197198199200201202203204205206207208209210211212213214215216217218219220221222223224225226227228229230231232233234235236237238239240241242243244245246247248249250251252253254255256257258259260261262263264265266267268269270271272273274275276277278279280281282283284285286287288289290291292293294295296297298299300301302303304305306307308309310311312313314315316317318319320321322323324325326327328329330331332333334335336337338339340341342343344345346347348349350351352353354355356357358359360361362363364365366367368369370371372373374375376377378379380381382383384385386387388389390391392393394395396397398399400401402403404405406407408409410411412413414415416417418419420421422423424425426427428429430431432433434435436437438439440441442443444445446447448449450451452453454455456457458459460461462463464465466467468469470471472473474475476477478479480481482483484485486487488489490491492493494495496497498499500501502503504505506507508509510511512513514515516517518519520521522523524525526527528529530531532533534535536537538539540541542543544545546547548549550551552553554555556557558559560561562563564565566567568569570571572573574575576577578579580581582583584585586587588589590591592593594595596597598599600601602603604605606607608609610611612613614615616617618619620621622623624625626627628629630631632633634635636637638639640641642643644645646647648649650651652653654655656657658659660661662663664665666667668669670671672673674675676677678679680681682683684685686687688689690691692693694695696697698699700701702703704705706707708709710711712713714715716717718719720721722723724725726727728729730731732733734735736737738739740741742743744745746747748749750751752753754755756757758759760761762763764765766767768769770771772773774775776777778779780781782783784785786787788789790791792793794795796797798799800801802803804805806807808809810811812813814815816817818819820821822823824825826827828829830831832833834835836837838839840841842843844845 | 
							- using System;
 
- using ICSharpCode.SharpZipLib.Checksum;
 
- namespace ICSharpCode.SharpZipLib.Zip.Compression
 
- {
 
- 	/// <summary>
 
- 	/// Strategies for deflater
 
- 	/// </summary>
 
- 	public enum DeflateStrategy
 
- 	{
 
- 		/// <summary>
 
- 		/// The default strategy
 
- 		/// </summary>
 
- 		Default = 0,
 
- 		/// <summary>
 
- 		/// This strategy will only allow longer string repetitions.  It is
 
- 		/// useful for random data with a small character set.
 
- 		/// </summary>
 
- 		Filtered = 1,
 
- 		/// <summary>
 
- 		/// This strategy will not look for string repetitions at all.  It
 
- 		/// only encodes with Huffman trees (which means, that more common
 
- 		/// characters get a smaller encoding.
 
- 		/// </summary>
 
- 		HuffmanOnly = 2
 
- 	}
 
- 	// DEFLATE ALGORITHM:
 
- 	//
 
- 	// The uncompressed stream is inserted into the window array.  When
 
- 	// the window array is full the first half is thrown away and the
 
- 	// second half is copied to the beginning.
 
- 	//
 
- 	// The head array is a hash table.  Three characters build a hash value
 
- 	// and they the value points to the corresponding index in window of
 
- 	// the last string with this hash.  The prev array implements a
 
- 	// linked list of matches with the same hash: prev[index & WMASK] points
 
- 	// to the previous index with the same hash.
 
- 	//
 
- 	/// <summary>
 
- 	/// Low level compression engine for deflate algorithm which uses a 32K sliding window
 
- 	/// with secondary compression from Huffman/Shannon-Fano codes.
 
- 	/// </summary>
 
- 	public class DeflaterEngine
 
- 	{
 
- 		#region Constants
 
- 		const int TooFar = 4096;
 
- 		#endregion
 
- 		#region Constructors
 
- 		/// <summary>
 
- 		/// Construct instance with pending buffer
 
- 		/// </summary>
 
- 		/// <param name="pending">
 
- 		/// Pending buffer to use
 
- 		/// </param>>
 
- 		public DeflaterEngine(DeflaterPending pending)
 
- 		{
 
- 			this.pending = pending;
 
- 			huffman = new DeflaterHuffman(pending);
 
- 			adler = new Adler32();
 
- 			window = new byte[2 * DeflaterConstants.WSIZE];
 
- 			head = new short[DeflaterConstants.HASH_SIZE];
 
- 			prev = new short[DeflaterConstants.WSIZE];
 
- 			// We start at index 1, to avoid an implementation deficiency, that
 
- 			// we cannot build a repeat pattern at index 0.
 
- 			blockStart = strstart = 1;
 
- 		}
 
- 		#endregion
 
- 		/// <summary>
 
- 		/// Deflate drives actual compression of data
 
- 		/// </summary>
 
- 		/// <param name="flush">True to flush input buffers</param>
 
- 		/// <param name="finish">Finish deflation with the current input.</param>
 
- 		/// <returns>Returns true if progress has been made.</returns>
 
- 		public bool Deflate(bool flush, bool finish)
 
- 		{
 
- 			bool progress;
 
- 			do {
 
- 				FillWindow();
 
- 				bool canFlush = flush && (inputOff == inputEnd);
 
- #if DebugDeflation
 
- 				if (DeflaterConstants.DEBUGGING) {
 
- 					Console.WriteLine("window: [" + blockStart + "," + strstart + ","
 
- 								+ lookahead + "], " + compressionFunction + "," + canFlush);
 
- 				}
 
- #endif
 
- 				switch (compressionFunction) {
 
- 					case DeflaterConstants.DEFLATE_STORED:
 
- 						progress = DeflateStored(canFlush, finish);
 
- 						break;
 
- 					case DeflaterConstants.DEFLATE_FAST:
 
- 						progress = DeflateFast(canFlush, finish);
 
- 						break;
 
- 					case DeflaterConstants.DEFLATE_SLOW:
 
- 						progress = DeflateSlow(canFlush, finish);
 
- 						break;
 
- 					default:
 
- 						throw new InvalidOperationException("unknown compressionFunction");
 
- 				}
 
- 			} while (pending.IsFlushed && progress); // repeat while we have no pending output and progress was made
 
- 			return progress;
 
- 		}
 
- 		/// <summary>
 
- 		/// Sets input data to be deflated.  Should only be called when <code>NeedsInput()</code>
 
- 		/// returns true
 
- 		/// </summary>
 
- 		/// <param name="buffer">The buffer containing input data.</param>
 
- 		/// <param name="offset">The offset of the first byte of data.</param>
 
- 		/// <param name="count">The number of bytes of data to use as input.</param>
 
- 		public void SetInput(byte[] buffer, int offset, int count)
 
- 		{
 
- 			if (buffer == null) {
 
- 				throw new ArgumentNullException("nameof(buffer)");
 
- 			}
 
- 			if (offset < 0) {
 
- 				throw new ArgumentOutOfRangeException("nameof(offset)");
 
- 			}
 
- 			if (count < 0) {
 
- 				throw new ArgumentOutOfRangeException("nameof(count)");
 
- 			}
 
- 			if (inputOff < inputEnd) {
 
- 				throw new InvalidOperationException("Old input was not completely processed");
 
- 			}
 
- 			int end = offset + count;
 
- 			/* We want to throw an ArrayIndexOutOfBoundsException early.  The
 
- 			* check is very tricky: it also handles integer wrap around.
 
- 			*/
 
- 			if ((offset > end) || (end > buffer.Length)) {
 
- 				throw new ArgumentOutOfRangeException("nameof(count)");
 
- 			}
 
- 			inputBuf = buffer;
 
- 			inputOff = offset;
 
- 			inputEnd = end;
 
- 		}
 
- 		/// <summary>
 
- 		/// Determines if more <see cref="SetInput">input</see> is needed.
 
- 		/// </summary>
 
- 		/// <returns>Return true if input is needed via <see cref="SetInput">SetInput</see></returns>
 
- 		public bool NeedsInput()
 
- 		{
 
- 			return (inputEnd == inputOff);
 
- 		}
 
- 		/// <summary>
 
- 		/// Set compression dictionary
 
- 		/// </summary>
 
- 		/// <param name="buffer">The buffer containing the dictionary data</param>
 
- 		/// <param name="offset">The offset in the buffer for the first byte of data</param>
 
- 		/// <param name="length">The length of the dictionary data.</param>
 
- 		public void SetDictionary(byte[] buffer, int offset, int length)
 
- 		{
 
- #if DebugDeflation
 
- 			if (DeflaterConstants.DEBUGGING && (strstart != 1) )
 
- 			{
 
- 				throw new InvalidOperationException("strstart not 1");
 
- 			}
 
- #endif
 
- 			adler.Update(buffer, offset, length);
 
- 			if (length < DeflaterConstants.MIN_MATCH) {
 
- 				return;
 
- 			}
 
- 			if (length > DeflaterConstants.MAX_DIST) {
 
- 				offset += length - DeflaterConstants.MAX_DIST;
 
- 				length = DeflaterConstants.MAX_DIST;
 
- 			}
 
- 			System.Array.Copy(buffer, offset, window, strstart, length);
 
- 			UpdateHash();
 
- 			--length;
 
- 			while (--length > 0) {
 
- 				InsertString();
 
- 				strstart++;
 
- 			}
 
- 			strstart += 2;
 
- 			blockStart = strstart;
 
- 		}
 
- 		/// <summary>
 
- 		/// Reset internal state
 
- 		/// </summary>
 
- 		public void Reset()
 
- 		{
 
- 			huffman.Reset();
 
- 			adler.Reset();
 
- 			blockStart = strstart = 1;
 
- 			lookahead = 0;
 
- 			totalIn = 0;
 
- 			prevAvailable = false;
 
- 			matchLen = DeflaterConstants.MIN_MATCH - 1;
 
- 			for (int i = 0; i < DeflaterConstants.HASH_SIZE; i++) {
 
- 				head[i] = 0;
 
- 			}
 
- 			for (int i = 0; i < DeflaterConstants.WSIZE; i++) {
 
- 				prev[i] = 0;
 
- 			}
 
- 		}
 
- 		/// <summary>
 
- 		/// Reset Adler checksum
 
- 		/// </summary>
 
- 		public void ResetAdler()
 
- 		{
 
- 			adler.Reset();
 
- 		}
 
- 		/// <summary>
 
- 		/// Get current value of Adler checksum
 
- 		/// </summary>
 
- 		public int Adler {
 
- 			get {
 
- 				return unchecked((int)adler.Value);
 
- 			}
 
- 		}
 
- 		/// <summary>
 
- 		/// Total data processed
 
- 		/// </summary>
 
- 		public long TotalIn {
 
- 			get {
 
- 				return totalIn;
 
- 			}
 
- 		}
 
- 		/// <summary>
 
- 		/// Get/set the <see cref="DeflateStrategy">deflate strategy</see>
 
- 		/// </summary>
 
- 		public DeflateStrategy Strategy {
 
- 			get {
 
- 				return strategy;
 
- 			}
 
- 			set {
 
- 				strategy = value;
 
- 			}
 
- 		}
 
- 		/// <summary>
 
- 		/// Set the deflate level (0-9)
 
- 		/// </summary>
 
- 		/// <param name="level">The value to set the level to.</param>
 
- 		public void SetLevel(int level)
 
- 		{
 
- 			if ((level < 0) || (level > 9)) {
 
- 				throw new ArgumentOutOfRangeException("nameof(level)");
 
- 			}
 
- 			goodLength = DeflaterConstants.GOOD_LENGTH[level];
 
- 			max_lazy = DeflaterConstants.MAX_LAZY[level];
 
- 			niceLength = DeflaterConstants.NICE_LENGTH[level];
 
- 			max_chain = DeflaterConstants.MAX_CHAIN[level];
 
- 			if (DeflaterConstants.COMPR_FUNC[level] != compressionFunction) {
 
- #if DebugDeflation
 
- 				if (DeflaterConstants.DEBUGGING) {
 
- 				   Console.WriteLine("Change from " + compressionFunction + " to "
 
- 										  + DeflaterConstants.COMPR_FUNC[level]);
 
- 				}
 
- #endif
 
- 				switch (compressionFunction) {
 
- 					case DeflaterConstants.DEFLATE_STORED:
 
- 						if (strstart > blockStart) {
 
- 							huffman.FlushStoredBlock(window, blockStart,
 
- 								strstart - blockStart, false);
 
- 							blockStart = strstart;
 
- 						}
 
- 						UpdateHash();
 
- 						break;
 
- 					case DeflaterConstants.DEFLATE_FAST:
 
- 						if (strstart > blockStart) {
 
- 							huffman.FlushBlock(window, blockStart, strstart - blockStart,
 
- 								false);
 
- 							blockStart = strstart;
 
- 						}
 
- 						break;
 
- 					case DeflaterConstants.DEFLATE_SLOW:
 
- 						if (prevAvailable) {
 
- 							huffman.TallyLit(window[strstart - 1] & 0xff);
 
- 						}
 
- 						if (strstart > blockStart) {
 
- 							huffman.FlushBlock(window, blockStart, strstart - blockStart, false);
 
- 							blockStart = strstart;
 
- 						}
 
- 						prevAvailable = false;
 
- 						matchLen = DeflaterConstants.MIN_MATCH - 1;
 
- 						break;
 
- 				}
 
- 				compressionFunction = DeflaterConstants.COMPR_FUNC[level];
 
- 			}
 
- 		}
 
- 		/// <summary>
 
- 		/// Fill the window
 
- 		/// </summary>
 
- 		public void FillWindow()
 
- 		{
 
- 			/* If the window is almost full and there is insufficient lookahead,
 
- 			 * move the upper half to the lower one to make room in the upper half.
 
- 			 */
 
- 			if (strstart >= DeflaterConstants.WSIZE + DeflaterConstants.MAX_DIST) {
 
- 				SlideWindow();
 
- 			}
 
- 			/* If there is not enough lookahead, but still some input left,
 
- 			 * read in the input
 
- 			 */
 
- 			if (lookahead < DeflaterConstants.MIN_LOOKAHEAD && inputOff < inputEnd) {
 
- 				int more = 2 * DeflaterConstants.WSIZE - lookahead - strstart;
 
- 				if (more > inputEnd - inputOff) {
 
- 					more = inputEnd - inputOff;
 
- 				}
 
- 				System.Array.Copy(inputBuf, inputOff, window, strstart + lookahead, more);
 
- 				adler.Update(inputBuf, inputOff, more);
 
- 				inputOff += more;
 
- 				totalIn += more;
 
- 				lookahead += more;
 
- 			}
 
- 			if (lookahead >= DeflaterConstants.MIN_MATCH) {
 
- 				UpdateHash();
 
- 			}
 
- 		}
 
- 		void UpdateHash()
 
- 		{
 
- 			/*
 
- 						if (DEBUGGING) {
 
- 							Console.WriteLine("updateHash: "+strstart);
 
- 						}
 
- 			*/
 
- 			ins_h = (window[strstart] << DeflaterConstants.HASH_SHIFT) ^ window[strstart + 1];
 
- 		}
 
- 		/// <summary>
 
- 		/// Inserts the current string in the head hash and returns the previous
 
- 		/// value for this hash.
 
- 		/// </summary>
 
- 		/// <returns>The previous hash value</returns>
 
- 		int InsertString()
 
- 		{
 
- 			short match;
 
- 			int hash = ((ins_h << DeflaterConstants.HASH_SHIFT) ^ window[strstart + (DeflaterConstants.MIN_MATCH - 1)]) & DeflaterConstants.HASH_MASK;
 
- #if DebugDeflation
 
- 			if (DeflaterConstants.DEBUGGING)
 
- 			{
 
- 				if (hash != (((window[strstart] << (2*HASH_SHIFT)) ^
 
- 								  (window[strstart + 1] << HASH_SHIFT) ^
 
- 								  (window[strstart + 2])) & HASH_MASK)) {
 
- 						throw new SharpZipBaseException("hash inconsistent: " + hash + "/"
 
- 												+window[strstart] + ","
 
- 												+window[strstart + 1] + ","
 
- 												+window[strstart + 2] + "," + HASH_SHIFT);
 
- 					}
 
- 			}
 
- #endif
 
- 			prev[strstart & DeflaterConstants.WMASK] = match = head[hash];
 
- 			head[hash] = unchecked((short)strstart);
 
- 			ins_h = hash;
 
- 			return match & 0xffff;
 
- 		}
 
- 		void SlideWindow()
 
- 		{
 
- 			Array.Copy(window, DeflaterConstants.WSIZE, window, 0, DeflaterConstants.WSIZE);
 
- 			matchStart -= DeflaterConstants.WSIZE;
 
- 			strstart -= DeflaterConstants.WSIZE;
 
- 			blockStart -= DeflaterConstants.WSIZE;
 
- 			// Slide the hash table (could be avoided with 32 bit values
 
- 			// at the expense of memory usage).
 
- 			for (int i = 0; i < DeflaterConstants.HASH_SIZE; ++i) {
 
- 				int m = head[i] & 0xffff;
 
- 				head[i] = (short)(m >= DeflaterConstants.WSIZE ? (m - DeflaterConstants.WSIZE) : 0);
 
- 			}
 
- 			// Slide the prev table.
 
- 			for (int i = 0; i < DeflaterConstants.WSIZE; i++) {
 
- 				int m = prev[i] & 0xffff;
 
- 				prev[i] = (short)(m >= DeflaterConstants.WSIZE ? (m - DeflaterConstants.WSIZE) : 0);
 
- 			}
 
- 		}
 
- 		/// <summary>
 
- 		/// Find the best (longest) string in the window matching the
 
- 		/// string starting at strstart.
 
- 		///
 
- 		/// Preconditions:
 
- 		/// <code>
 
- 		/// strstart + DeflaterConstants.MAX_MATCH <= window.length.</code>
 
- 		/// </summary>
 
- 		/// <param name="curMatch"></param>
 
- 		/// <returns>True if a match greater than the minimum length is found</returns>
 
- 		bool FindLongestMatch( int curMatch )
 
- 		{
 
-         int match;
 
-         int scan = strstart;
 
-         // scanMax is the highest position that we can look at
 
-         int scanMax = scan + Math.Min( DeflaterConstants.MAX_MATCH, lookahead ) - 1;
 
-         int limit = Math.Max( scan - DeflaterConstants.MAX_DIST, 0 );
 
-         byte[] window = this.window;
 
-         short[] prev = this.prev;
 
-         int chainLength = this.max_chain;
 
-         int niceLength = Math.Min( this.niceLength, lookahead );
 
-           matchLen = Math.Max( matchLen, DeflaterConstants.MIN_MATCH - 1 );
 
-           if (scan + matchLen > scanMax) return false;
 
-         byte scan_end1 = window[scan + matchLen - 1];
 
-         byte scan_end = window[scan + matchLen];
 
-           // Do not waste too much time if we already have a good match:
 
-           if (matchLen >= this.goodLength) chainLength >>= 2;
 
-           do
 
-           {
 
-             match = curMatch;
 
-             scan = strstart;
 
-             if (window[match + matchLen] != scan_end
 
-              || window[match + matchLen - 1] != scan_end1
 
-              || window[match] != window[scan]
 
-              || window[++match] != window[++scan])
 
-             {
 
-               continue;
 
-             }
 
-             // scan is set to strstart+1 and the comparison passed, so
 
-             // scanMax - scan is the maximum number of bytes we can compare.
 
-             // below we compare 8 bytes at a time, so first we compare
 
-             // (scanMax - scan) % 8 bytes, so the remainder is a multiple of 8
 
-             switch( (scanMax - scan) % 8 )
 
-             {
 
-             case 1: if (window[++scan] == window[++match]) break;
 
-               break;
 
-             case 2: if (window[++scan] == window[++match]
 
-               && window[++scan] == window[++match]) break;
 
-               break;
 
-             case 3: if (window[++scan] == window[++match]
 
-               && window[++scan] == window[++match]
 
-               && window[++scan] == window[++match]) break;
 
-               break;
 
-             case 4: if (window[++scan] == window[++match]
 
-               && window[++scan] == window[++match]
 
-               && window[++scan] == window[++match]
 
-               && window[++scan] == window[++match]) break;
 
-               break;
 
-             case 5: if (window[++scan] == window[++match]
 
-               && window[++scan] == window[++match]
 
-               && window[++scan] == window[++match]
 
-               && window[++scan] == window[++match]
 
-               && window[++scan] == window[++match]) break;
 
-               break;
 
-             case 6: if (window[++scan] == window[++match]
 
-               && window[++scan] == window[++match]
 
-               && window[++scan] == window[++match]
 
-               && window[++scan] == window[++match]
 
-               && window[++scan] == window[++match]
 
-               && window[++scan] == window[++match]) break;
 
-               break;
 
-             case 7: if (window[++scan] == window[++match]
 
-               && window[++scan] == window[++match]
 
-               && window[++scan] == window[++match]
 
-               && window[++scan] == window[++match]
 
-               && window[++scan] == window[++match]
 
-               && window[++scan] == window[++match]
 
-               && window[++scan] == window[++match]) break;
 
-               break;
 
-             }
 
-             if (window[scan] == window[match])
 
-             {
 
-             /* We check for insufficient lookahead only every 8th comparison;
 
-              * the 256th check will be made at strstart + 258 unless lookahead is
 
-              * exhausted first.
 
-              */
 
-               do
 
-               {
 
-                 if (scan == scanMax)
 
-                 {
 
-                   ++scan;     // advance to first position not matched
 
-                   ++match;
 
-                   break;
 
-                 }
 
-               }
 
-               while (window[++scan] == window[++match]
 
-                   && window[++scan] == window[++match]
 
-                   && window[++scan] == window[++match]
 
-                   && window[++scan] == window[++match]
 
-                   && window[++scan] == window[++match]
 
-                   && window[++scan] == window[++match]
 
-                   && window[++scan] == window[++match]
 
-                   && window[++scan] == window[++match]);
 
-             }
 
-             if (scan - strstart > matchLen)
 
-             {
 
-               #if DebugDeflation
 
-               if (DeflaterConstants.DEBUGGING && (ins_h == 0) )
 
-               Console.Error.WriteLine("Found match: " + curMatch + "-" + (scan - strstart));
 
-               #endif
 
-               matchStart = curMatch;
 
-               matchLen = scan - strstart;
 
-               if (matchLen >= niceLength)
 
-                 break;
 
-               scan_end1 = window[scan - 1];
 
-               scan_end = window[scan];
 
-             }
 
-           } while ((curMatch = (prev[curMatch & DeflaterConstants.WMASK] & 0xffff)) > limit && 0 != --chainLength );
 
-           return matchLen >= DeflaterConstants.MIN_MATCH;
 
-         }
 
- 		bool DeflateStored(bool flush, bool finish)
 
- 		{
 
- 			if (!flush && (lookahead == 0)) {
 
- 				return false;
 
- 			}
 
- 			strstart += lookahead;
 
- 			lookahead = 0;
 
- 			int storedLength = strstart - blockStart;
 
- 			if ((storedLength >= DeflaterConstants.MAX_BLOCK_SIZE) || // Block is full
 
- 				(blockStart < DeflaterConstants.WSIZE && storedLength >= DeflaterConstants.MAX_DIST) ||   // Block may move out of window
 
- 				flush) {
 
- 				bool lastBlock = finish;
 
- 				if (storedLength > DeflaterConstants.MAX_BLOCK_SIZE) {
 
- 					storedLength = DeflaterConstants.MAX_BLOCK_SIZE;
 
- 					lastBlock = false;
 
- 				}
 
- #if DebugDeflation
 
- 				if (DeflaterConstants.DEBUGGING)
 
- 				{
 
- 				   Console.WriteLine("storedBlock[" + storedLength + "," + lastBlock + "]");
 
- 				}
 
- #endif
 
- 				huffman.FlushStoredBlock(window, blockStart, storedLength, lastBlock);
 
- 				blockStart += storedLength;
 
- 				return !lastBlock;
 
- 			}
 
- 			return true;
 
- 		}
 
- 		bool DeflateFast(bool flush, bool finish)
 
- 		{
 
- 			if (lookahead < DeflaterConstants.MIN_LOOKAHEAD && !flush) {
 
- 				return false;
 
- 			}
 
- 			while (lookahead >= DeflaterConstants.MIN_LOOKAHEAD || flush) {
 
- 				if (lookahead == 0) {
 
- 					// We are flushing everything
 
- 					huffman.FlushBlock(window, blockStart, strstart - blockStart, finish);
 
- 					blockStart = strstart;
 
- 					return false;
 
- 				}
 
- 				if (strstart > 2 * DeflaterConstants.WSIZE - DeflaterConstants.MIN_LOOKAHEAD) {
 
- 					/* slide window, as FindLongestMatch needs this.
 
- 					 * This should only happen when flushing and the window
 
- 					 * is almost full.
 
- 					 */
 
- 					SlideWindow();
 
- 				}
 
- 				int hashHead;
 
- 				if (lookahead >= DeflaterConstants.MIN_MATCH &&
 
- 					(hashHead = InsertString()) != 0 &&
 
- 					strategy != DeflateStrategy.HuffmanOnly &&
 
- 					strstart - hashHead <= DeflaterConstants.MAX_DIST &&
 
- 					FindLongestMatch(hashHead)) {
 
- 					// longestMatch sets matchStart and matchLen
 
- #if DebugDeflation
 
- 					if (DeflaterConstants.DEBUGGING)
 
- 					{
 
- 						for (int i = 0 ; i < matchLen; i++) {
 
- 							if (window[strstart + i] != window[matchStart + i]) {
 
- 								throw new SharpZipBaseException("Match failure");
 
- 							}
 
- 						}
 
- 					}
 
- #endif
 
- 					bool full = huffman.TallyDist(strstart - matchStart, matchLen);
 
- 					lookahead -= matchLen;
 
- 					if (matchLen <= max_lazy && lookahead >= DeflaterConstants.MIN_MATCH) {
 
- 						while (--matchLen > 0) {
 
- 							++strstart;
 
- 							InsertString();
 
- 						}
 
- 						++strstart;
 
- 					} else {
 
- 						strstart += matchLen;
 
- 						if (lookahead >= DeflaterConstants.MIN_MATCH - 1) {
 
- 							UpdateHash();
 
- 						}
 
- 					}
 
- 					matchLen = DeflaterConstants.MIN_MATCH - 1;
 
- 					if (!full) {
 
- 						continue;
 
- 					}
 
- 				} else {
 
- 					// No match found
 
- 					huffman.TallyLit(window[strstart] & 0xff);
 
- 					++strstart;
 
- 					--lookahead;
 
- 				}
 
- 				if (huffman.IsFull()) {
 
- 					bool lastBlock = finish && (lookahead == 0);
 
- 					huffman.FlushBlock(window, blockStart, strstart - blockStart, lastBlock);
 
- 					blockStart = strstart;
 
- 					return !lastBlock;
 
- 				}
 
- 			}
 
- 			return true;
 
- 		}
 
- 		bool DeflateSlow(bool flush, bool finish)
 
- 		{
 
- 			if (lookahead < DeflaterConstants.MIN_LOOKAHEAD && !flush) {
 
- 				return false;
 
- 			}
 
- 			while (lookahead >= DeflaterConstants.MIN_LOOKAHEAD || flush) {
 
- 				if (lookahead == 0) {
 
- 					if (prevAvailable) {
 
- 						huffman.TallyLit(window[strstart - 1] & 0xff);
 
- 					}
 
- 					prevAvailable = false;
 
- 					// We are flushing everything
 
- #if DebugDeflation
 
- 					if (DeflaterConstants.DEBUGGING && !flush)
 
- 					{
 
- 						throw new SharpZipBaseException("Not flushing, but no lookahead");
 
- 					}
 
- #endif
 
- 					huffman.FlushBlock(window, blockStart, strstart - blockStart,
 
- 						finish);
 
- 					blockStart = strstart;
 
- 					return false;
 
- 				}
 
- 				if (strstart >= 2 * DeflaterConstants.WSIZE - DeflaterConstants.MIN_LOOKAHEAD) {
 
- 					/* slide window, as FindLongestMatch needs this.
 
- 					 * This should only happen when flushing and the window
 
- 					 * is almost full.
 
- 					 */
 
- 					SlideWindow();
 
- 				}
 
- 				int prevMatch = matchStart;
 
- 				int prevLen = matchLen;
 
- 				if (lookahead >= DeflaterConstants.MIN_MATCH) {
 
- 					int hashHead = InsertString();
 
- 					if (strategy != DeflateStrategy.HuffmanOnly &&
 
- 						hashHead != 0 &&
 
- 						strstart - hashHead <= DeflaterConstants.MAX_DIST &&
 
- 						FindLongestMatch(hashHead)) {
 
- 						// longestMatch sets matchStart and matchLen
 
- 						// Discard match if too small and too far away
 
- 						if (matchLen <= 5 && (strategy == DeflateStrategy.Filtered || (matchLen == DeflaterConstants.MIN_MATCH && strstart - matchStart > TooFar))) {
 
- 							matchLen = DeflaterConstants.MIN_MATCH - 1;
 
- 						}
 
- 					}
 
- 				}
 
- 				// previous match was better
 
- 				if ((prevLen >= DeflaterConstants.MIN_MATCH) && (matchLen <= prevLen)) {
 
- #if DebugDeflation
 
- 					if (DeflaterConstants.DEBUGGING)
 
- 					{
 
- 					   for (int i = 0 ; i < matchLen; i++) {
 
- 						  if (window[strstart-1+i] != window[prevMatch + i])
 
- 							 throw new SharpZipBaseException();
 
- 						}
 
- 					}
 
- #endif
 
- 					huffman.TallyDist(strstart - 1 - prevMatch, prevLen);
 
- 					prevLen -= 2;
 
- 					do {
 
- 						strstart++;
 
- 						lookahead--;
 
- 						if (lookahead >= DeflaterConstants.MIN_MATCH) {
 
- 							InsertString();
 
- 						}
 
- 					} while (--prevLen > 0);
 
- 					strstart++;
 
- 					lookahead--;
 
- 					prevAvailable = false;
 
- 					matchLen = DeflaterConstants.MIN_MATCH - 1;
 
- 				} else {
 
- 					if (prevAvailable) {
 
- 						huffman.TallyLit(window[strstart - 1] & 0xff);
 
- 					}
 
- 					prevAvailable = true;
 
- 					strstart++;
 
- 					lookahead--;
 
- 				}
 
- 				if (huffman.IsFull()) {
 
- 					int len = strstart - blockStart;
 
- 					if (prevAvailable) {
 
- 						len--;
 
- 					}
 
- 					bool lastBlock = (finish && (lookahead == 0) && !prevAvailable);
 
- 					huffman.FlushBlock(window, blockStart, len, lastBlock);
 
- 					blockStart += len;
 
- 					return !lastBlock;
 
- 				}
 
- 			}
 
- 			return true;
 
- 		}
 
- 		#region Instance Fields
 
- 		// Hash index of string to be inserted
 
- 		int ins_h;
 
- 		/// <summary>
 
- 		/// Hashtable, hashing three characters to an index for window, so
 
- 		/// that window[index]..window[index+2] have this hash code.
 
- 		/// Note that the array should really be unsigned short, so you need
 
- 		/// to and the values with 0xffff.
 
- 		/// </summary>
 
- 		short[] head;
 
- 		/// <summary>
 
- 		/// <code>prev[index & WMASK]</code> points to the previous index that has the
 
- 		/// same hash code as the string starting at index.  This way
 
- 		/// entries with the same hash code are in a linked list.
 
- 		/// Note that the array should really be unsigned short, so you need
 
- 		/// to and the values with 0xffff.
 
- 		/// </summary>
 
- 		short[] prev;
 
- 		int matchStart;
 
- 		// Length of best match
 
- 		int matchLen;
 
- 		// Set if previous match exists
 
- 		bool prevAvailable;
 
- 		int blockStart;
 
- 		/// <summary>
 
- 		/// Points to the current character in the window.
 
- 		/// </summary>
 
- 		int strstart;
 
- 		/// <summary>
 
- 		/// lookahead is the number of characters starting at strstart in
 
- 		/// window that are valid.
 
- 		/// So window[strstart] until window[strstart+lookahead-1] are valid
 
- 		/// characters.
 
- 		/// </summary>
 
- 		int lookahead;
 
- 		/// <summary>
 
- 		/// This array contains the part of the uncompressed stream that
 
- 		/// is of relevance.  The current character is indexed by strstart.
 
- 		/// </summary>
 
- 		byte[] window;
 
- 		DeflateStrategy strategy;
 
- 		int max_chain, max_lazy, niceLength, goodLength;
 
- 		/// <summary>
 
- 		/// The current compression function.
 
- 		/// </summary>
 
- 		int compressionFunction;
 
- 		/// <summary>
 
- 		/// The input data for compression.
 
- 		/// </summary>
 
- 		byte[] inputBuf;
 
- 		/// <summary>
 
- 		/// The total bytes of input read.
 
- 		/// </summary>
 
- 		long totalIn;
 
- 		/// <summary>
 
- 		/// The offset into inputBuf, where input data starts.
 
- 		/// </summary>
 
- 		int inputOff;
 
- 		/// <summary>
 
- 		/// The end offset of the input data.
 
- 		/// </summary>
 
- 		int inputEnd;
 
- 		DeflaterPending pending;
 
- 		DeflaterHuffman huffman;
 
- 		/// <summary>
 
- 		/// The adler checksum
 
- 		/// </summary>
 
- 		Adler32 adler;
 
- 		#endregion
 
- 	}
 
- }
 
 
  |