// Inflate.cs
// ------------------------------------------------------------------
//
// Copyright (c) 2009 Dino Chiesa and Microsoft Corporation.
// All rights reserved.
//
// This code module is part of DotNetZip, a zipfile class library.
//
// ------------------------------------------------------------------
//
// This code is licensed under the Microsoft Public License.
// See the file License.txt for the license details.
// More info on: http://dotnetzip.codeplex.com
//
// ------------------------------------------------------------------
//
// last saved (in emacs):
// Time-stamp: <2010-January-08 18:32:12>
//
// ------------------------------------------------------------------
//
// This module defines classes for decompression. This code is derived
// from the jzlib implementation of zlib, but significantly modified.
// The object model is not the same, and many of the behaviors are
// different.  Nonetheless, in keeping with the license for jzlib, I am
// reproducing the copyright to that code here.
//
// ------------------------------------------------------------------
//
// Copyright (c) 2000,2001,2002,2003 ymnk, JCraft,Inc. All rights reserved.
//
// Redistribution and use in source and binary forms, with or without
// modification, are permitted provided that the following conditions are met:
//
// 1. Redistributions of source code must retain the above copyright notice,
// this list of conditions and the following disclaimer.
//
// 2. Redistributions in binary form must reproduce the above copyright
// notice, this list of conditions and the following disclaimer in
// the documentation and/or other materials provided with the distribution.
//
// 3. The names of the authors may not be used to endorse or promote products
// derived from this software without specific prior written permission.
//
// THIS SOFTWARE IS PROVIDED ``AS IS'' AND ANY EXPRESSED OR IMPLIED WARRANTIES,
// INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND
// FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL JCRAFT,
// INC. OR ANY CONTRIBUTORS TO THIS SOFTWARE BE LIABLE FOR ANY DIRECT, INDIRECT,
// INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA,
// OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
// LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
// NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE,
// EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
//
// -----------------------------------------------------------------------
//
// This program is based on zlib-1.1.3; credit to authors
// Jean-loup Gailly(jloup@gzip.org) and Mark Adler(madler@alumni.caltech.edu)
// and contributors of zlib.
//
// -----------------------------------------------------------------------

using System;

namespace Ionic.Zlib
{
	sealed class InflateBlocks
	{
		private const int MANY = 1440;

		// Table for deflate from PKZIP's appnote.txt.
		internal static readonly int[] border = new int[]
		{ 16, 17, 18, 0, 8, 7, 9, 6, 10, 5, 11, 4, 12, 3, 13, 2, 14, 1, 15 };

		private enum InflateBlockMode
		{
			TYPE = 0,                     // get type bits (3, including end bit)
			LENS = 1,                     // get lengths for stored
			STORED = 2,                     // processing stored block
			TABLE = 3,                     // get table lengths
			BTREE = 4,                     // get bit lengths tree for a dynamic block
			DTREE = 5,                     // get length, distance trees for a dynamic block
			CODES = 6,                     // processing fixed or dynamic block
			DRY = 7,                     // output remaining window bytes
			DONE = 8,                     // finished last block, done
			BAD = 9,                     // ot a data error--stuck here
		}

		private InflateBlockMode mode;                    // current inflate_block mode

		internal int left;                                // if STORED, bytes left to copy

		internal int table;                               // table lengths (14 bits)
		internal int index;                               // index into blens (or border)
		internal int[] blens;                             // bit lengths of codes
		internal int[] bb = new int[1];                   // bit length tree depth
		internal int[] tb = new int[1];                   // bit length decoding tree

		internal InflateCodes codes = new InflateCodes(); // if CODES, current state

		internal int last;                                // true if this block is the last block

		internal ZlibCodec _codec;                        // pointer back to this zlib stream

		// mode independent information
		internal int bitk;                                // bits in bit buffer
		internal int bitb;                                // bit buffer
		internal int[] hufts;                             // single malloc for tree space
		internal byte[] window;                           // sliding window
		internal int end;                                 // one byte after sliding window
		internal int readAt;                              // window read pointer
		internal int writeAt;                             // window write pointer
		internal System.Object checkfn;                   // check function
		internal uint check;                              // check on output

		internal InfTree inftree = new InfTree();

		internal InflateBlocks(ZlibCodec codec, System.Object checkfn, int w)
		{
			_codec = codec;
			hufts = new int[MANY * 3];
			window = new byte[w];
			end = w;
			this.checkfn = checkfn;
			mode = InflateBlockMode.TYPE;
			Reset();
		}

		internal uint Reset()
		{
			uint oldCheck = check;
			mode = InflateBlockMode.TYPE;
			bitk = 0;
			bitb = 0;
			readAt = writeAt = 0;

			if (checkfn != null)
				_codec._Adler32 = check = Adler.Adler32(0, null, 0, 0);
			return oldCheck;
		}


		internal int Process(int r)
		{
			int t; // temporary storage
			int b; // bit buffer
			int k; // bits in bit buffer
			int p; // input data pointer
			int n; // bytes available there
			int q; // output window write pointer
			int m; // bytes to end of window or read pointer

			// copy input/output information to locals (UPDATE macro restores)

			p = _codec.NextIn;
			n = _codec.AvailableBytesIn;
			b = bitb;
			k = bitk;

			q = writeAt;
			m = (int)(q < readAt ? readAt - q - 1 : end - q);


			// process input based on current state
			while (true)
			{
				switch (mode)
				{
					case InflateBlockMode.TYPE:

						while (k < (3))
						{
							if (n != 0)
							{
								r = ZlibConstants.Z_OK;
							}
							else
							{
								bitb = b; bitk = k;
								_codec.AvailableBytesIn = n;
								_codec.TotalBytesIn += p - _codec.NextIn;
								_codec.NextIn = p;
								writeAt = q;
								return Flush(r);
							}

							n--;
							b |= (_codec.InputBuffer[p++] & 0xff) << k;
							k += 8;
						}
						t = (int)(b & 7);
						last = t & 1;

						switch ((uint)t >> 1)
						{
							case 0:  // stored
								b >>= 3; k -= (3);
								t = k & 7; // go to byte boundary
								b >>= t; k -= t;
								mode = InflateBlockMode.LENS; // get length of stored block
								break;

							case 1:  // fixed
								int[] bl = new int[1];
								int[] bd = new int[1];
								int[][] tl = new int[1][];
								int[][] td = new int[1][];
								InfTree.inflate_trees_fixed(bl, bd, tl, td, _codec);
								codes.Init(bl[0], bd[0], tl[0], 0, td[0], 0);
								b >>= 3; k -= 3;
								mode = InflateBlockMode.CODES;
								break;

							case 2:  // dynamic
								b >>= 3; k -= 3;
								mode = InflateBlockMode.TABLE;
								break;

							case 3:  // illegal
								b >>= 3; k -= 3;
								mode = InflateBlockMode.BAD;
								_codec.Message = "invalid block type";
								r = ZlibConstants.Z_DATA_ERROR;
								bitb = b; bitk = k;
								_codec.AvailableBytesIn = n;
								_codec.TotalBytesIn += p - _codec.NextIn;
								_codec.NextIn = p;
								writeAt = q;
								return Flush(r);
						}
						break;

					case InflateBlockMode.LENS:

						while (k < (32))
						{
							if (n != 0)
							{
								r = ZlibConstants.Z_OK;
							}
							else
							{
								bitb = b; bitk = k;
								_codec.AvailableBytesIn = n;
								_codec.TotalBytesIn += p - _codec.NextIn;
								_codec.NextIn = p;
								writeAt = q;
								return Flush(r);
							}
								;
							n--;
							b |= (_codec.InputBuffer[p++] & 0xff) << k;
							k += 8;
						}

						if ((((~b) >> 16) & 0xffff) != (b & 0xffff))
						{
							mode = InflateBlockMode.BAD;
							_codec.Message = "invalid stored block lengths";
							r = ZlibConstants.Z_DATA_ERROR;

							bitb = b; bitk = k;
							_codec.AvailableBytesIn = n;
							_codec.TotalBytesIn += p - _codec.NextIn;
							_codec.NextIn = p;
							writeAt = q;
							return Flush(r);
						}
						left = (b & 0xffff);
						b = k = 0; // dump bits
						mode = left != 0 ? InflateBlockMode.STORED : (last != 0 ? InflateBlockMode.DRY : InflateBlockMode.TYPE);
						break;

					case InflateBlockMode.STORED:
						if (n == 0)
						{
							bitb = b; bitk = k;
							_codec.AvailableBytesIn = n;
							_codec.TotalBytesIn += p - _codec.NextIn;
							_codec.NextIn = p;
							writeAt = q;
							return Flush(r);
						}

						if (m == 0)
						{
							if (q == end && readAt != 0)
							{
								q = 0; m = (int)(q < readAt ? readAt - q - 1 : end - q);
							}
							if (m == 0)
							{
								writeAt = q;
								r = Flush(r);
								q = writeAt; m = (int)(q < readAt ? readAt - q - 1 : end - q);
								if (q == end && readAt != 0)
								{
									q = 0; m = (int)(q < readAt ? readAt - q - 1 : end - q);
								}
								if (m == 0)
								{
									bitb = b; bitk = k;
									_codec.AvailableBytesIn = n;
									_codec.TotalBytesIn += p - _codec.NextIn;
									_codec.NextIn = p;
									writeAt = q;
									return Flush(r);
								}
							}
						}
						r = ZlibConstants.Z_OK;

						t = left;
						if (t > n)
							t = n;
						if (t > m)
							t = m;
						Array.Copy(_codec.InputBuffer, p, window, q, t);
						p += t; n -= t;
						q += t; m -= t;
						if ((left -= t) != 0)
							break;
						mode = last != 0 ? InflateBlockMode.DRY : InflateBlockMode.TYPE;
						break;

					case InflateBlockMode.TABLE:

						while (k < (14))
						{
							if (n != 0)
							{
								r = ZlibConstants.Z_OK;
							}
							else
							{
								bitb = b; bitk = k;
								_codec.AvailableBytesIn = n;
								_codec.TotalBytesIn += p - _codec.NextIn;
								_codec.NextIn = p;
								writeAt = q;
								return Flush(r);
							}

							n--;
							b |= (_codec.InputBuffer[p++] & 0xff) << k;
							k += 8;
						}

						table = t = (b & 0x3fff);
						if ((t & 0x1f) > 29 || ((t >> 5) & 0x1f) > 29)
						{
							mode = InflateBlockMode.BAD;
							_codec.Message = "too many length or distance symbols";
							r = ZlibConstants.Z_DATA_ERROR;

							bitb = b; bitk = k;
							_codec.AvailableBytesIn = n;
							_codec.TotalBytesIn += p - _codec.NextIn;
							_codec.NextIn = p;
							writeAt = q;
							return Flush(r);
						}
						t = 258 + (t & 0x1f) + ((t >> 5) & 0x1f);
						if (blens == null || blens.Length < t)
						{
							blens = new int[t];
						}
						else
						{
							Array.Clear(blens, 0, t);
							// for (int i = 0; i < t; i++)
							// {
							//     blens[i] = 0;
							// }
						}

						b >>= 14;
						k -= 14;


						index = 0;
						mode = InflateBlockMode.BTREE;
						goto case InflateBlockMode.BTREE;

					case InflateBlockMode.BTREE:
						while (index < 4 + (table >> 10))
						{
							while (k < (3))
							{
								if (n != 0)
								{
									r = ZlibConstants.Z_OK;
								}
								else
								{
									bitb = b; bitk = k;
									_codec.AvailableBytesIn = n;
									_codec.TotalBytesIn += p - _codec.NextIn;
									_codec.NextIn = p;
									writeAt = q;
									return Flush(r);
								}

								n--;
								b |= (_codec.InputBuffer[p++] & 0xff) << k;
								k += 8;
							}

							blens[border[index++]] = b & 7;

							b >>= 3; k -= 3;
						}

						while (index < 19)
						{
							blens[border[index++]] = 0;
						}

						bb[0] = 7;
						t = inftree.inflate_trees_bits(blens, bb, tb, hufts, _codec);
						if (t != ZlibConstants.Z_OK)
						{
							r = t;
							if (r == ZlibConstants.Z_DATA_ERROR)
							{
								blens = null;
								mode = InflateBlockMode.BAD;
							}

							bitb = b; bitk = k;
							_codec.AvailableBytesIn = n;
							_codec.TotalBytesIn += p - _codec.NextIn;
							_codec.NextIn = p;
							writeAt = q;
							return Flush(r);
						}

						index = 0;
						mode = InflateBlockMode.DTREE;
						goto case InflateBlockMode.DTREE;

					case InflateBlockMode.DTREE:
						while (true)
						{
							t = table;
							if (!(index < 258 + (t & 0x1f) + ((t >> 5) & 0x1f)))
							{
								break;
							}

							int i, j, c;

							t = bb[0];

							while (k < t)
							{
								if (n != 0)
								{
									r = ZlibConstants.Z_OK;
								}
								else
								{
									bitb = b; bitk = k;
									_codec.AvailableBytesIn = n;
									_codec.TotalBytesIn += p - _codec.NextIn;
									_codec.NextIn = p;
									writeAt = q;
									return Flush(r);
								}

								n--;
								b |= (_codec.InputBuffer[p++] & 0xff) << k;
								k += 8;
							}

							t = hufts[(tb[0] + (b & InternalInflateConstants.InflateMask[t])) * 3 + 1];
							c = hufts[(tb[0] + (b & InternalInflateConstants.InflateMask[t])) * 3 + 2];

							if (c < 16)
							{
								b >>= t; k -= t;
								blens[index++] = c;
							}
							else
							{
								// c == 16..18
								i = c == 18 ? 7 : c - 14;
								j = c == 18 ? 11 : 3;

								while (k < (t + i))
								{
									if (n != 0)
									{
										r = ZlibConstants.Z_OK;
									}
									else
									{
										bitb = b; bitk = k;
										_codec.AvailableBytesIn = n;
										_codec.TotalBytesIn += p - _codec.NextIn;
										_codec.NextIn = p;
										writeAt = q;
										return Flush(r);
									}

									n--;
									b |= (_codec.InputBuffer[p++] & 0xff) << k;
									k += 8;
								}

								b >>= t; k -= t;

								j += (b & InternalInflateConstants.InflateMask[i]);

								b >>= i; k -= i;

								i = index;
								t = table;
								if (i + j > 258 + (t & 0x1f) + ((t >> 5) & 0x1f) || (c == 16 && i < 1))
								{
									blens = null;
									mode = InflateBlockMode.BAD;
									_codec.Message = "invalid bit length repeat";
									r = ZlibConstants.Z_DATA_ERROR;

									bitb = b; bitk = k;
									_codec.AvailableBytesIn = n;
									_codec.TotalBytesIn += p - _codec.NextIn;
									_codec.NextIn = p;
									writeAt = q;
									return Flush(r);
								}

								c = (c == 16) ? blens[i - 1] : 0;
								do
								{
									blens[i++] = c;
								}
								while (--j != 0);
								index = i;
							}
						}

						tb[0] = -1;
						{
							int[] bl = new int[] { 9 };  // must be <= 9 for lookahead assumptions
							int[] bd = new int[] { 6 }; // must be <= 9 for lookahead assumptions
							int[] tl = new int[1];
							int[] td = new int[1];

							t = table;
							t = inftree.inflate_trees_dynamic(257 + (t & 0x1f), 1 + ((t >> 5) & 0x1f), blens, bl, bd, tl, td, hufts, _codec);

							if (t != ZlibConstants.Z_OK)
							{
								if (t == ZlibConstants.Z_DATA_ERROR)
								{
									blens = null;
									mode = InflateBlockMode.BAD;
								}
								r = t;

								bitb = b; bitk = k;
								_codec.AvailableBytesIn = n;
								_codec.TotalBytesIn += p - _codec.NextIn;
								_codec.NextIn = p;
								writeAt = q;
								return Flush(r);
							}
							codes.Init(bl[0], bd[0], hufts, tl[0], hufts, td[0]);
						}
						mode = InflateBlockMode.CODES;
						goto case InflateBlockMode.CODES;

					case InflateBlockMode.CODES:
						bitb = b; bitk = k;
						_codec.AvailableBytesIn = n;
						_codec.TotalBytesIn += p - _codec.NextIn;
						_codec.NextIn = p;
						writeAt = q;

						r = codes.Process(this, r);
						if (r != ZlibConstants.Z_STREAM_END)
						{
							return Flush(r);
						}

						r = ZlibConstants.Z_OK;
						p = _codec.NextIn;
						n = _codec.AvailableBytesIn;
						b = bitb;
						k = bitk;
						q = writeAt;
						m = (int)(q < readAt ? readAt - q - 1 : end - q);

						if (last == 0)
						{
							mode = InflateBlockMode.TYPE;
							break;
						}
						mode = InflateBlockMode.DRY;
						goto case InflateBlockMode.DRY;

					case InflateBlockMode.DRY:
						writeAt = q;
						r = Flush(r);
						q = writeAt; m = (int)(q < readAt ? readAt - q - 1 : end - q);
						if (readAt != writeAt)
						{
							bitb = b; bitk = k;
							_codec.AvailableBytesIn = n;
							_codec.TotalBytesIn += p - _codec.NextIn;
							_codec.NextIn = p;
							writeAt = q;
							return Flush(r);
						}
						mode = InflateBlockMode.DONE;
						goto case InflateBlockMode.DONE;

					case InflateBlockMode.DONE:
						r = ZlibConstants.Z_STREAM_END;
						bitb = b;
						bitk = k;
						_codec.AvailableBytesIn = n;
						_codec.TotalBytesIn += p - _codec.NextIn;
						_codec.NextIn = p;
						writeAt = q;
						return Flush(r);

					case InflateBlockMode.BAD:
						r = ZlibConstants.Z_DATA_ERROR;

						bitb = b; bitk = k;
						_codec.AvailableBytesIn = n;
						_codec.TotalBytesIn += p - _codec.NextIn;
						_codec.NextIn = p;
						writeAt = q;
						return Flush(r);


					default:
						r = ZlibConstants.Z_STREAM_ERROR;

						bitb = b; bitk = k;
						_codec.AvailableBytesIn = n;
						_codec.TotalBytesIn += p - _codec.NextIn;
						_codec.NextIn = p;
						writeAt = q;
						return Flush(r);
				}
			}
		}


		internal void Free()
		{
			Reset();
			window = null;
			hufts = null;
		}

		internal void SetDictionary(byte[] d, int start, int n)
		{
			Array.Copy(d, start, window, 0, n);
			readAt = writeAt = n;
		}

		// Returns true if inflate is currently at the end of a block generated
		// by Z_SYNC_FLUSH or Z_FULL_FLUSH.
		internal int SyncPoint()
		{
			return mode == InflateBlockMode.LENS ? 1 : 0;
		}

		// copy as much as possible from the sliding window to the output area
		internal int Flush(int r)
		{
			int nBytes;

			for (int pass = 0; pass < 2; pass++)
			{
				if (pass == 0)
				{
					// compute number of bytes to copy as far as end of window
					nBytes = (int)((readAt <= writeAt ? writeAt : end) - readAt);
				}
				else
				{
					// compute bytes to copy
					nBytes = writeAt - readAt;
				}

				// workitem 8870
				if (nBytes == 0)
				{
					if (r == ZlibConstants.Z_BUF_ERROR)
						r = ZlibConstants.Z_OK;
					return r;
				}

				if (nBytes > _codec.AvailableBytesOut)
					nBytes = _codec.AvailableBytesOut;

				if (nBytes != 0 && r == ZlibConstants.Z_BUF_ERROR)
					r = ZlibConstants.Z_OK;

				// update counters
				_codec.AvailableBytesOut -= nBytes;
				_codec.TotalBytesOut += nBytes;

				// update check information
				if (checkfn != null)
					_codec._Adler32 = check = Adler.Adler32(check, window, readAt, nBytes);

				// copy as far as end of window
				Array.Copy(window, readAt, _codec.OutputBuffer, _codec.NextOut, nBytes);
				_codec.NextOut += nBytes;
				readAt += nBytes;

				// see if more to copy at beginning of window
				if (readAt == end && pass == 0)
				{
					// wrap pointers
					readAt = 0;
					if (writeAt == end)
						writeAt = 0;
				}
				else pass++;
			}

			// done
			return r;
		}
	}

	internal static class InternalInflateConstants
	{
		// And'ing with mask[n] masks the lower n bits
		internal static readonly int[] InflateMask = new int[] {
						0x00000000, 0x00000001, 0x00000003, 0x00000007,
						0x0000000f, 0x0000001f, 0x0000003f, 0x0000007f,
						0x000000ff, 0x000001ff, 0x000003ff, 0x000007ff,
						0x00000fff, 0x00001fff, 0x00003fff, 0x00007fff, 0x0000ffff };
	}

	sealed class InflateCodes
	{
		// waiting for "i:"=input,
		//             "o:"=output,
		//             "x:"=nothing
		private const int START = 0; // x: set up for LEN
		private const int LEN = 1; // i: get length/literal/eob next
		private const int LENEXT = 2; // i: getting length extra (have base)
		private const int DIST = 3; // i: get distance next
		private const int DISTEXT = 4; // i: getting distance extra
		private const int COPY = 5; // o: copying bytes in window, waiting for space
		private const int LIT = 6; // o: got literal, waiting for output space
		private const int WASH = 7; // o: got eob, possibly still output waiting
		private const int END = 8; // x: got eob and all data flushed
		private const int BADCODE = 9; // x: got error

		internal int mode;        // current inflate_codes mode

		// mode dependent information
		internal int len;

		internal int[] tree;      // pointer into tree
		internal int tree_index = 0;
		internal int need;        // bits needed

		internal int lit;

		// if EXT or COPY, where and how much
		internal int bitsToGet;   // bits to get for extra
		internal int dist;        // distance back to copy from

		internal byte lbits;      // ltree bits decoded per branch
		internal byte dbits;      // dtree bits decoder per branch
		internal int[] ltree;     // literal/length/eob tree
		internal int ltree_index; // literal/length/eob tree
		internal int[] dtree;     // distance tree
		internal int dtree_index; // distance tree

		internal InflateCodes()
		{
		}

		internal void Init(int bl, int bd, int[] tl, int tl_index, int[] td, int td_index)
		{
			mode = START;
			lbits = (byte)bl;
			dbits = (byte)bd;
			ltree = tl;
			ltree_index = tl_index;
			dtree = td;
			dtree_index = td_index;
			tree = null;
		}

		internal int Process(InflateBlocks blocks, int r)
		{
			int j;      // temporary storage
			int tindex; // temporary pointer
			int e;      // extra bits or operation
			int b = 0;  // bit buffer
			int k = 0;  // bits in bit buffer
			int p = 0;  // input data pointer
			int n;      // bytes available there
			int q;      // output window write pointer
			int m;      // bytes to end of window or read pointer
			int f;      // pointer to copy strings from

			ZlibCodec z = blocks._codec;

			// copy input/output information to locals (UPDATE macro restores)
			p = z.NextIn;
			n = z.AvailableBytesIn;
			b = blocks.bitb;
			k = blocks.bitk;
			q = blocks.writeAt; m = q < blocks.readAt ? blocks.readAt - q - 1 : blocks.end - q;

			// process input and output based on current state
			while (true)
			{
				switch (mode)
				{
					// waiting for "i:"=input, "o:"=output, "x:"=nothing
					case START:  // x: set up for LEN
						if (m >= 258 && n >= 10)
						{
							blocks.bitb = b; blocks.bitk = k;
							z.AvailableBytesIn = n;
							z.TotalBytesIn += p - z.NextIn;
							z.NextIn = p;
							blocks.writeAt = q;
							r = InflateFast(lbits, dbits, ltree, ltree_index, dtree, dtree_index, blocks, z);

							p = z.NextIn;
							n = z.AvailableBytesIn;
							b = blocks.bitb;
							k = blocks.bitk;
							q = blocks.writeAt; m = q < blocks.readAt ? blocks.readAt - q - 1 : blocks.end - q;

							if (r != ZlibConstants.Z_OK)
							{
								mode = (r == ZlibConstants.Z_STREAM_END) ? WASH : BADCODE;
								break;
							}
						}
						need = lbits;
						tree = ltree;
						tree_index = ltree_index;

						mode = LEN;
						goto case LEN;

					case LEN:  // i: get length/literal/eob next
						j = need;

						while (k < j)
						{
							if (n != 0)
								r = ZlibConstants.Z_OK;
							else
							{
								blocks.bitb = b; blocks.bitk = k;
								z.AvailableBytesIn = n;
								z.TotalBytesIn += p - z.NextIn;
								z.NextIn = p;
								blocks.writeAt = q;
								return blocks.Flush(r);
							}
							n--;
							b |= (z.InputBuffer[p++] & 0xff) << k;
							k += 8;
						}

						tindex = (tree_index + (b & InternalInflateConstants.InflateMask[j])) * 3;

						b >>= (tree[tindex + 1]);
						k -= (tree[tindex + 1]);

						e = tree[tindex];

						if (e == 0)
						{
							// literal
							lit = tree[tindex + 2];
							mode = LIT;
							break;
						}
						if ((e & 16) != 0)
						{
							// length
							bitsToGet = e & 15;
							len = tree[tindex + 2];
							mode = LENEXT;
							break;
						}
						if ((e & 64) == 0)
						{
							// next table
							need = e;
							tree_index = tindex / 3 + tree[tindex + 2];
							break;
						}
						if ((e & 32) != 0)
						{
							// end of block
							mode = WASH;
							break;
						}
						mode = BADCODE; // invalid code
						z.Message = "invalid literal/length code";
						r = ZlibConstants.Z_DATA_ERROR;

						blocks.bitb = b; blocks.bitk = k;
						z.AvailableBytesIn = n;
						z.TotalBytesIn += p - z.NextIn;
						z.NextIn = p;
						blocks.writeAt = q;
						return blocks.Flush(r);


					case LENEXT:  // i: getting length extra (have base)
						j = bitsToGet;

						while (k < j)
						{
							if (n != 0)
								r = ZlibConstants.Z_OK;
							else
							{
								blocks.bitb = b; blocks.bitk = k;
								z.AvailableBytesIn = n; z.TotalBytesIn += p - z.NextIn; z.NextIn = p;
								blocks.writeAt = q;
								return blocks.Flush(r);
							}
							n--; b |= (z.InputBuffer[p++] & 0xff) << k;
							k += 8;
						}

						len += (b & InternalInflateConstants.InflateMask[j]);

						b >>= j;
						k -= j;

						need = dbits;
						tree = dtree;
						tree_index = dtree_index;
						mode = DIST;
						goto case DIST;

					case DIST:  // i: get distance next
						j = need;

						while (k < j)
						{
							if (n != 0)
								r = ZlibConstants.Z_OK;
							else
							{
								blocks.bitb = b; blocks.bitk = k;
								z.AvailableBytesIn = n; z.TotalBytesIn += p - z.NextIn; z.NextIn = p;
								blocks.writeAt = q;
								return blocks.Flush(r);
							}
							n--; b |= (z.InputBuffer[p++] & 0xff) << k;
							k += 8;
						}

						tindex = (tree_index + (b & InternalInflateConstants.InflateMask[j])) * 3;

						b >>= tree[tindex + 1];
						k -= tree[tindex + 1];

						e = (tree[tindex]);
						if ((e & 0x10) != 0)
						{
							// distance
							bitsToGet = e & 15;
							dist = tree[tindex + 2];
							mode = DISTEXT;
							break;
						}
						if ((e & 64) == 0)
						{
							// next table
							need = e;
							tree_index = tindex / 3 + tree[tindex + 2];
							break;
						}
						mode = BADCODE; // invalid code
						z.Message = "invalid distance code";
						r = ZlibConstants.Z_DATA_ERROR;

						blocks.bitb = b; blocks.bitk = k;
						z.AvailableBytesIn = n; z.TotalBytesIn += p - z.NextIn; z.NextIn = p;
						blocks.writeAt = q;
						return blocks.Flush(r);


					case DISTEXT:  // i: getting distance extra
						j = bitsToGet;

						while (k < j)
						{
							if (n != 0)
								r = ZlibConstants.Z_OK;
							else
							{
								blocks.bitb = b; blocks.bitk = k;
								z.AvailableBytesIn = n; z.TotalBytesIn += p - z.NextIn; z.NextIn = p;
								blocks.writeAt = q;
								return blocks.Flush(r);
							}
							n--; b |= (z.InputBuffer[p++] & 0xff) << k;
							k += 8;
						}

						dist += (b & InternalInflateConstants.InflateMask[j]);

						b >>= j;
						k -= j;

						mode = COPY;
						goto case COPY;

					case COPY:  // o: copying bytes in window, waiting for space
						f = q - dist;
						while (f < 0)
						{
							// modulo window size-"while" instead
							f += blocks.end; // of "if" handles invalid distances
						}
						while (len != 0)
						{
							if (m == 0)
							{
								if (q == blocks.end && blocks.readAt != 0)
								{
									q = 0; m = q < blocks.readAt ? blocks.readAt - q - 1 : blocks.end - q;
								}
								if (m == 0)
								{
									blocks.writeAt = q; r = blocks.Flush(r);
									q = blocks.writeAt; m = q < blocks.readAt ? blocks.readAt - q - 1 : blocks.end - q;

									if (q == blocks.end && blocks.readAt != 0)
									{
										q = 0; m = q < blocks.readAt ? blocks.readAt - q - 1 : blocks.end - q;
									}

									if (m == 0)
									{
										blocks.bitb = b; blocks.bitk = k;
										z.AvailableBytesIn = n;
										z.TotalBytesIn += p - z.NextIn;
										z.NextIn = p;
										blocks.writeAt = q;
										return blocks.Flush(r);
									}
								}
							}

							blocks.window[q++] = blocks.window[f++]; m--;

							if (f == blocks.end)
								f = 0;
							len--;
						}
						mode = START;
						break;

					case LIT:  // o: got literal, waiting for output space
						if (m == 0)
						{
							if (q == blocks.end && blocks.readAt != 0)
							{
								q = 0; m = q < blocks.readAt ? blocks.readAt - q - 1 : blocks.end - q;
							}
							if (m == 0)
							{
								blocks.writeAt = q; r = blocks.Flush(r);
								q = blocks.writeAt; m = q < blocks.readAt ? blocks.readAt - q - 1 : blocks.end - q;

								if (q == blocks.end && blocks.readAt != 0)
								{
									q = 0; m = q < blocks.readAt ? blocks.readAt - q - 1 : blocks.end - q;
								}
								if (m == 0)
								{
									blocks.bitb = b; blocks.bitk = k;
									z.AvailableBytesIn = n; z.TotalBytesIn += p - z.NextIn; z.NextIn = p;
									blocks.writeAt = q;
									return blocks.Flush(r);
								}
							}
						}
						r = ZlibConstants.Z_OK;

						blocks.window[q++] = (byte)lit; m--;

						mode = START;
						break;

					case WASH:  // o: got eob, possibly more output
						if (k > 7)
						{
							// return unused byte, if any
							k -= 8;
							n++;
							p--; // can always return one
						}

						blocks.writeAt = q; r = blocks.Flush(r);
						q = blocks.writeAt; m = q < blocks.readAt ? blocks.readAt - q - 1 : blocks.end - q;

						if (blocks.readAt != blocks.writeAt)
						{
							blocks.bitb = b; blocks.bitk = k;
							z.AvailableBytesIn = n; z.TotalBytesIn += p - z.NextIn; z.NextIn = p;
							blocks.writeAt = q;
							return blocks.Flush(r);
						}
						mode = END;
						goto case END;

					case END:
						r = ZlibConstants.Z_STREAM_END;
						blocks.bitb = b; blocks.bitk = k;
						z.AvailableBytesIn = n; z.TotalBytesIn += p - z.NextIn; z.NextIn = p;
						blocks.writeAt = q;
						return blocks.Flush(r);

					case BADCODE:  // x: got error

						r = ZlibConstants.Z_DATA_ERROR;

						blocks.bitb = b; blocks.bitk = k;
						z.AvailableBytesIn = n; z.TotalBytesIn += p - z.NextIn; z.NextIn = p;
						blocks.writeAt = q;
						return blocks.Flush(r);

					default:
						r = ZlibConstants.Z_STREAM_ERROR;

						blocks.bitb = b; blocks.bitk = k;
						z.AvailableBytesIn = n; z.TotalBytesIn += p - z.NextIn; z.NextIn = p;
						blocks.writeAt = q;
						return blocks.Flush(r);
				}
			}
		}


		// Called with number of bytes left to write in window at least 258
		// (the maximum string length) and number of input bytes available
		// at least ten.  The ten bytes are six bytes for the longest length/
		// distance pair plus four bytes for overloading the bit buffer.

		internal int InflateFast(int bl, int bd, int[] tl, int tl_index, int[] td, int td_index, InflateBlocks s, ZlibCodec z)
		{
			int t;        // temporary pointer
			int[] tp;     // temporary pointer
			int tp_index; // temporary pointer
			int e;        // extra bits or operation
			int b;        // bit buffer
			int k;        // bits in bit buffer
			int p;        // input data pointer
			int n;        // bytes available there
			int q;        // output window write pointer
			int m;        // bytes to end of window or read pointer
			int ml;       // mask for literal/length tree
			int md;       // mask for distance tree
			int c;        // bytes to copy
			int d;        // distance back to copy from
			int r;        // copy source pointer

			int tp_index_t_3; // (tp_index+t)*3

			// load input, output, bit values
			p = z.NextIn; n = z.AvailableBytesIn; b = s.bitb; k = s.bitk;
			q = s.writeAt; m = q < s.readAt ? s.readAt - q - 1 : s.end - q;

			// initialize masks
			ml = InternalInflateConstants.InflateMask[bl];
			md = InternalInflateConstants.InflateMask[bd];

			// do until not enough input or output space for fast loop
			do
			{
				// assume called with m >= 258 && n >= 10
				// get literal/length code
				while (k < (20))
				{
					// max bits for literal/length code
					n--;
					b |= (z.InputBuffer[p++] & 0xff) << k; k += 8;
				}

				t = b & ml;
				tp = tl;
				tp_index = tl_index;
				tp_index_t_3 = (tp_index + t) * 3;
				if ((e = tp[tp_index_t_3]) == 0)
				{
					b >>= (tp[tp_index_t_3 + 1]); k -= (tp[tp_index_t_3 + 1]);

					s.window[q++] = (byte)tp[tp_index_t_3 + 2];
					m--;
					continue;
				}
				do
				{

					b >>= (tp[tp_index_t_3 + 1]); k -= (tp[tp_index_t_3 + 1]);

					if ((e & 16) != 0)
					{
						e &= 15;
						c = tp[tp_index_t_3 + 2] + ((int)b & InternalInflateConstants.InflateMask[e]);

						b >>= e; k -= e;

						// decode distance base of block to copy
						while (k < 15)
						{
							// max bits for distance code
							n--;
							b |= (z.InputBuffer[p++] & 0xff) << k; k += 8;
						}

						t = b & md;
						tp = td;
						tp_index = td_index;
						tp_index_t_3 = (tp_index + t) * 3;
						e = tp[tp_index_t_3];

						do
						{

							b >>= (tp[tp_index_t_3 + 1]); k -= (tp[tp_index_t_3 + 1]);

							if ((e & 16) != 0)
							{
								// get extra bits to add to distance base
								e &= 15;
								while (k < e)
								{
									// get extra bits (up to 13)
									n--;
									b |= (z.InputBuffer[p++] & 0xff) << k; k += 8;
								}

								d = tp[tp_index_t_3 + 2] + (b & InternalInflateConstants.InflateMask[e]);

								b >>= e; k -= e;

								// do the copy
								m -= c;
								if (q >= d)
								{
									// offset before dest
									//  just copy
									r = q - d;
									if (q - r > 0 && 2 > (q - r))
									{
										s.window[q++] = s.window[r++]; // minimum count is three,
										s.window[q++] = s.window[r++]; // so unroll loop a little
										c -= 2;
									}
									else
									{
										Array.Copy(s.window, r, s.window, q, 2);
										q += 2; r += 2; c -= 2;
									}
								}
								else
								{
									// else offset after destination
									r = q - d;
									do
									{
										r += s.end; // force pointer in window
									}
									while (r < 0); // covers invalid distances
									e = s.end - r;
									if (c > e)
									{
										// if source crosses,
										c -= e; // wrapped copy
										if (q - r > 0 && e > (q - r))
										{
											do
											{
												s.window[q++] = s.window[r++];
											}
											while (--e != 0);
										}
										else
										{
											Array.Copy(s.window, r, s.window, q, e);
											q += e; r += e; e = 0;
										}
										r = 0; // copy rest from start of window
									}
								}

								// copy all or what's left
								if (q - r > 0 && c > (q - r))
								{
									do
									{
										s.window[q++] = s.window[r++];
									}
									while (--c != 0);
								}
								else
								{
									Array.Copy(s.window, r, s.window, q, c);
									q += c; r += c; c = 0;
								}
								break;
							}
							else if ((e & 64) == 0)
							{
								t += tp[tp_index_t_3 + 2];
								t += (b & InternalInflateConstants.InflateMask[e]);
								tp_index_t_3 = (tp_index + t) * 3;
								e = tp[tp_index_t_3];
							}
							else
							{
								z.Message = "invalid distance code";

								c = z.AvailableBytesIn - n; c = (k >> 3) < c ? k >> 3 : c; n += c; p -= c; k -= (c << 3);

								s.bitb = b; s.bitk = k;
								z.AvailableBytesIn = n; z.TotalBytesIn += p - z.NextIn; z.NextIn = p;
								s.writeAt = q;

								return ZlibConstants.Z_DATA_ERROR;
							}
						}
						while (true);
						break;
					}

					if ((e & 64) == 0)
					{
						t += tp[tp_index_t_3 + 2];
						t += (b & InternalInflateConstants.InflateMask[e]);
						tp_index_t_3 = (tp_index + t) * 3;
						if ((e = tp[tp_index_t_3]) == 0)
						{
							b >>= (tp[tp_index_t_3 + 1]); k -= (tp[tp_index_t_3 + 1]);
							s.window[q++] = (byte)tp[tp_index_t_3 + 2];
							m--;
							break;
						}
					}
					else if ((e & 32) != 0)
					{
						c = z.AvailableBytesIn - n; c = (k >> 3) < c ? k >> 3 : c; n += c; p -= c; k -= (c << 3);

						s.bitb = b; s.bitk = k;
						z.AvailableBytesIn = n; z.TotalBytesIn += p - z.NextIn; z.NextIn = p;
						s.writeAt = q;

						return ZlibConstants.Z_STREAM_END;
					}
					else
					{
						z.Message = "invalid literal/length code";

						c = z.AvailableBytesIn - n; c = (k >> 3) < c ? k >> 3 : c; n += c; p -= c; k -= (c << 3);

						s.bitb = b; s.bitk = k;
						z.AvailableBytesIn = n; z.TotalBytesIn += p - z.NextIn; z.NextIn = p;
						s.writeAt = q;

						return ZlibConstants.Z_DATA_ERROR;
					}
				}
				while (true);
			}
			while (m >= 258 && n >= 10);

			// not enough input or output--restore pointers and return
			c = z.AvailableBytesIn - n; c = (k >> 3) < c ? k >> 3 : c; n += c; p -= c; k -= (c << 3);

			s.bitb = b; s.bitk = k;
			z.AvailableBytesIn = n; z.TotalBytesIn += p - z.NextIn; z.NextIn = p;
			s.writeAt = q;

			return ZlibConstants.Z_OK;
		}
	}

	internal sealed class InflateManager
	{
		// preset dictionary flag in zlib header
		private const int PRESET_DICT = 0x20;

		private const int Z_DEFLATED = 8;

		private enum InflateManagerMode
		{
			METHOD = 0,  // waiting for method byte
			FLAG = 1,  // waiting for flag byte
			DICT4 = 2,  // four dictionary check bytes to go
			DICT3 = 3,  // three dictionary check bytes to go
			DICT2 = 4,  // two dictionary check bytes to go
			DICT1 = 5,  // one dictionary check byte to go
			DICT0 = 6,  // waiting for inflateSetDictionary
			BLOCKS = 7,  // decompressing blocks
			CHECK4 = 8,  // four check bytes to go
			CHECK3 = 9,  // three check bytes to go
			CHECK2 = 10, // two check bytes to go
			CHECK1 = 11, // one check byte to go
			DONE = 12, // finished check, done
			BAD = 13, // got an error--stay here
		}

		private InflateManagerMode mode; // current inflate mode
		internal ZlibCodec _codec; // pointer back to this zlib stream

		// mode dependent information
		internal int method; // if FLAGS, method byte

		// if CHECK, check values to compare
		internal uint computedCheck; // computed check value
		internal uint expectedCheck; // stream check value

		// if BAD, inflateSync's marker bytes count
		internal int marker;

		// mode independent information
		//internal int nowrap; // flag for no wrapper
		private bool _handleRfc1950HeaderBytes = true;
		internal bool HandleRfc1950HeaderBytes
		{
			get { return _handleRfc1950HeaderBytes; }
			set { _handleRfc1950HeaderBytes = value; }
		}
		internal int wbits; // log2(window size)  (8..15, defaults to 15)

		internal InflateBlocks blocks; // current inflate_blocks state

		public InflateManager() { }

		public InflateManager(bool expectRfc1950HeaderBytes)
		{
			_handleRfc1950HeaderBytes = expectRfc1950HeaderBytes;
		}

		internal int Reset()
		{
			_codec.TotalBytesIn = _codec.TotalBytesOut = 0;
			_codec.Message = null;
			mode = HandleRfc1950HeaderBytes ? InflateManagerMode.METHOD : InflateManagerMode.BLOCKS;
			blocks.Reset();
			return ZlibConstants.Z_OK;
		}

		internal int End()
		{
			if (blocks != null)
				blocks.Free();
			blocks = null;
			return ZlibConstants.Z_OK;
		}

		internal int Initialize(ZlibCodec codec, int w)
		{
			_codec = codec;
			_codec.Message = null;
			blocks = null;

			// handle undocumented nowrap option (no zlib header or check)
			//nowrap = 0;
			//if (w < 0)
			//{
			//    w = - w;
			//    nowrap = 1;
			//}

			// set window size
			if (w < 8 || w > 15)
			{
				End();
				throw new ZlibException("Bad window size.");

				//return ZlibConstants.Z_STREAM_ERROR;
			}
			wbits = w;

			blocks = new InflateBlocks(codec,
					HandleRfc1950HeaderBytes ? this : null,
					1 << w);

			// reset state
			Reset();
			return ZlibConstants.Z_OK;
		}


		internal int Inflate(FlushType flush)
		{
			int b;

			if (_codec.InputBuffer == null)
				throw new ZlibException("InputBuffer is null. ");

			//             int f = (flush == FlushType.Finish)
			//                 ? ZlibConstants.Z_BUF_ERROR
			//                 : ZlibConstants.Z_OK;

			// workitem 8870
			int f = ZlibConstants.Z_OK;
			int r = ZlibConstants.Z_BUF_ERROR;

			while (true)
			{
				switch (mode)
				{
					case InflateManagerMode.METHOD:
						if (_codec.AvailableBytesIn == 0) return r;
						r = f;
						_codec.AvailableBytesIn--;
						_codec.TotalBytesIn++;
						if (((method = _codec.InputBuffer[_codec.NextIn++]) & 0xf) != Z_DEFLATED)
						{
							mode = InflateManagerMode.BAD;
							_codec.Message = String.Format("unknown compression method (0x{0:X2})", method);
							marker = 5; // can't try inflateSync
							break;
						}
						if ((method >> 4) + 8 > wbits)
						{
							mode = InflateManagerMode.BAD;
							_codec.Message = String.Format("invalid window size ({0})", (method >> 4) + 8);
							marker = 5; // can't try inflateSync
							break;
						}
						mode = InflateManagerMode.FLAG;
						break;


					case InflateManagerMode.FLAG:
						if (_codec.AvailableBytesIn == 0) return r;
						r = f;
						_codec.AvailableBytesIn--;
						_codec.TotalBytesIn++;
						b = (_codec.InputBuffer[_codec.NextIn++]) & 0xff;

						if ((((method << 8) + b) % 31) != 0)
						{
							mode = InflateManagerMode.BAD;
							_codec.Message = "incorrect header check";
							marker = 5; // can't try inflateSync
							break;
						}

						mode = ((b & PRESET_DICT) == 0)
								? InflateManagerMode.BLOCKS
								: InflateManagerMode.DICT4;
						break;

					case InflateManagerMode.DICT4:
						if (_codec.AvailableBytesIn == 0) return r;
						r = f;
						_codec.AvailableBytesIn--;
						_codec.TotalBytesIn++;
						expectedCheck = (uint)((_codec.InputBuffer[_codec.NextIn++] << 24) & 0xff000000);
						mode = InflateManagerMode.DICT3;
						break;

					case InflateManagerMode.DICT3:
						if (_codec.AvailableBytesIn == 0) return r;
						r = f;
						_codec.AvailableBytesIn--;
						_codec.TotalBytesIn++;
						expectedCheck += (uint)((_codec.InputBuffer[_codec.NextIn++] << 16) & 0x00ff0000);
						mode = InflateManagerMode.DICT2;
						break;

					case InflateManagerMode.DICT2:

						if (_codec.AvailableBytesIn == 0) return r;
						r = f;
						_codec.AvailableBytesIn--;
						_codec.TotalBytesIn++;
						expectedCheck += (uint)((_codec.InputBuffer[_codec.NextIn++] << 8) & 0x0000ff00);
						mode = InflateManagerMode.DICT1;
						break;


					case InflateManagerMode.DICT1:
						if (_codec.AvailableBytesIn == 0) return r;
						r = f;
						_codec.AvailableBytesIn--; _codec.TotalBytesIn++;
						expectedCheck += (uint)(_codec.InputBuffer[_codec.NextIn++] & 0x000000ff);
						_codec._Adler32 = expectedCheck;
						mode = InflateManagerMode.DICT0;
						return ZlibConstants.Z_NEED_DICT;


					case InflateManagerMode.DICT0:
						mode = InflateManagerMode.BAD;
						_codec.Message = "need dictionary";
						marker = 0; // can try inflateSync
						return ZlibConstants.Z_STREAM_ERROR;


					case InflateManagerMode.BLOCKS:
						r = blocks.Process(r);
						if (r == ZlibConstants.Z_DATA_ERROR)
						{
							mode = InflateManagerMode.BAD;
							marker = 0; // can try inflateSync
							break;
						}

						if (r == ZlibConstants.Z_OK) r = f;

						if (r != ZlibConstants.Z_STREAM_END)
							return r;

						r = f;
						computedCheck = blocks.Reset();
						if (!HandleRfc1950HeaderBytes)
						{
							mode = InflateManagerMode.DONE;
							return ZlibConstants.Z_STREAM_END;
						}
						mode = InflateManagerMode.CHECK4;
						break;

					case InflateManagerMode.CHECK4:
						if (_codec.AvailableBytesIn == 0) return r;
						r = f;
						_codec.AvailableBytesIn--;
						_codec.TotalBytesIn++;
						expectedCheck = (uint)((_codec.InputBuffer[_codec.NextIn++] << 24) & 0xff000000);
						mode = InflateManagerMode.CHECK3;
						break;

					case InflateManagerMode.CHECK3:
						if (_codec.AvailableBytesIn == 0) return r;
						r = f;
						_codec.AvailableBytesIn--; _codec.TotalBytesIn++;
						expectedCheck += (uint)((_codec.InputBuffer[_codec.NextIn++] << 16) & 0x00ff0000);
						mode = InflateManagerMode.CHECK2;
						break;

					case InflateManagerMode.CHECK2:
						if (_codec.AvailableBytesIn == 0) return r;
						r = f;
						_codec.AvailableBytesIn--;
						_codec.TotalBytesIn++;
						expectedCheck += (uint)((_codec.InputBuffer[_codec.NextIn++] << 8) & 0x0000ff00);
						mode = InflateManagerMode.CHECK1;
						break;

					case InflateManagerMode.CHECK1:
						if (_codec.AvailableBytesIn == 0) return r;
						r = f;
						_codec.AvailableBytesIn--; _codec.TotalBytesIn++;
						expectedCheck += (uint)(_codec.InputBuffer[_codec.NextIn++] & 0x000000ff);
						if (computedCheck != expectedCheck)
						{
							mode = InflateManagerMode.BAD;
							_codec.Message = "incorrect data check";
							marker = 5; // can't try inflateSync
							break;
						}
						mode = InflateManagerMode.DONE;
						return ZlibConstants.Z_STREAM_END;

					case InflateManagerMode.DONE:
						return ZlibConstants.Z_STREAM_END;

					case InflateManagerMode.BAD:
						throw new ZlibException(String.Format("Bad state ({0})", _codec.Message));

					default:
						throw new ZlibException("Stream error.");

				}
			}
		}



		internal int SetDictionary(byte[] dictionary)
		{
			int index = 0;
			int length = dictionary.Length;
			if (mode != InflateManagerMode.DICT0)
				throw new ZlibException("Stream error.");

			if (Adler.Adler32(1, dictionary, 0, dictionary.Length) != _codec._Adler32)
			{
				return ZlibConstants.Z_DATA_ERROR;
			}

			_codec._Adler32 = Adler.Adler32(0, null, 0, 0);

			if (length >= (1 << wbits))
			{
				length = (1 << wbits) - 1;
				index = dictionary.Length - length;
			}
			blocks.SetDictionary(dictionary, index, length);
			mode = InflateManagerMode.BLOCKS;
			return ZlibConstants.Z_OK;
		}


		private static readonly byte[] mark = new byte[] { 0, 0, 0xff, 0xff };

		internal int Sync()
		{
			int n; // number of bytes to look at
			int p; // pointer to bytes
			int m; // number of marker bytes found in a row
			long r, w; // temporaries to save total_in and total_out

			// set up
			if (mode != InflateManagerMode.BAD)
			{
				mode = InflateManagerMode.BAD;
				marker = 0;
			}
			if ((n = _codec.AvailableBytesIn) == 0)
				return ZlibConstants.Z_BUF_ERROR;
			p = _codec.NextIn;
			m = marker;

			// search
			while (n != 0 && m < 4)
			{
				if (_codec.InputBuffer[p] == mark[m])
				{
					m++;
				}
				else if (_codec.InputBuffer[p] != 0)
				{
					m = 0;
				}
				else
				{
					m = 4 - m;
				}
				p++; n--;
			}

			// restore
			_codec.TotalBytesIn += p - _codec.NextIn;
			_codec.NextIn = p;
			_codec.AvailableBytesIn = n;
			marker = m;

			// return no joy or set up to restart on a new block
			if (m != 4)
			{
				return ZlibConstants.Z_DATA_ERROR;
			}
			r = _codec.TotalBytesIn;
			w = _codec.TotalBytesOut;
			Reset();
			_codec.TotalBytesIn = r;
			_codec.TotalBytesOut = w;
			mode = InflateManagerMode.BLOCKS;
			return ZlibConstants.Z_OK;
		}


		// Returns true if inflate is currently at the end of a block generated
		// by Z_SYNC_FLUSH or Z_FULL_FLUSH. This function is used by one PPP
		// implementation to provide an additional safety check. PPP uses Z_SYNC_FLUSH
		// but removes the length bytes of the resulting empty stored block. When
		// decompressing, PPP checks that at the end of input packet, inflate is
		// waiting for these length bytes.
		internal int SyncPoint(ZlibCodec z)
		{
			return blocks.SyncPoint();
		}
	}
}