// Inflater.cs
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//
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// Copyright (C) 2001 Mike Krueger
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// Copyright (C) 2004 John Reilly
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//
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// This file was translated from java, it was part of the GNU Classpath
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// Copyright (C) 2001 Free Software Foundation, Inc.
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//
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// This program is free software; you can redistribute it and/or
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// modify it under the terms of the GNU General Public License
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// as published by the Free Software Foundation; either version 2
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// of the License, or (at your option) any later version.
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//
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// This program is distributed in the hope that it will be useful,
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// but WITHOUT ANY WARRANTY; without even the implied warranty of
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// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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// GNU General Public License for more details.
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//
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// You should have received a copy of the GNU General Public License
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// along with this program; if not, write to the Free Software
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// Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
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//
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// Linking this library statically or dynamically with other modules is
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// making a combined work based on this library. Thus, the terms and
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// conditions of the GNU General Public License cover the whole
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// combination.
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//
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// As a special exception, the copyright holders of this library give you
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// permission to link this library with independent modules to produce an
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// executable, regardless of the license terms of these independent
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// modules, and to copy and distribute the resulting executable under
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// terms of your choice, provided that you also meet, for each linked
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// independent module, the terms and conditions of the license of that
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// module. An independent module is a module which is not derived from
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// or based on this library. If you modify this library, you may extend
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// this exception to your version of the library, but you are not
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// obligated to do so. If you do not wish to do so, delete this
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// exception statement from your version.
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using System;
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using ICSharpCode.SharpZipLib.Checksums;
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using ICSharpCode.SharpZipLib.Zip.Compression.Streams;
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namespace ICSharpCode.SharpZipLib.Zip.Compression
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{
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/// <summary>
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/// Inflater is used to decompress data that has been compressed according
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/// to the "deflate" standard described in rfc1951.
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///
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/// By default Zlib (rfc1950) headers and footers are expected in the input.
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/// You can use constructor <code> public Inflater(bool noHeader)</code> passing true
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/// if there is no Zlib header information
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///
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/// The usage is as following. First you have to set some input with
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/// <code>SetInput()</code>, then Inflate() it. If inflate doesn't
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/// inflate any bytes there may be three reasons:
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/// <ul>
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/// <li>IsNeedingInput() returns true because the input buffer is empty.
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/// You have to provide more input with <code>SetInput()</code>.
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/// NOTE: IsNeedingInput() also returns true when, the stream is finished.
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/// </li>
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/// <li>IsNeedingDictionary() returns true, you have to provide a preset
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/// dictionary with <code>SetDictionary()</code>.</li>
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/// <li>IsFinished returns true, the inflater has finished.</li>
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/// </ul>
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/// Once the first output byte is produced, a dictionary will not be
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/// needed at a later stage.
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///
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/// author of the original java version : John Leuner, Jochen Hoenicke
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/// </summary>
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public class Inflater
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{
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#region Constants/Readonly
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/// <summary>
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/// Copy lengths for literal codes 257..285
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/// </summary>
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static readonly int[] CPLENS = {
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3, 4, 5, 6, 7, 8, 9, 10, 11, 13, 15, 17, 19, 23, 27, 31,
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35, 43, 51, 59, 67, 83, 99, 115, 131, 163, 195, 227, 258
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};
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/// <summary>
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/// Extra bits for literal codes 257..285
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/// </summary>
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static readonly int[] CPLEXT = {
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0, 0, 0, 0, 0, 0, 0, 0, 1, 1, 1, 1, 2, 2, 2, 2,
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3, 3, 3, 3, 4, 4, 4, 4, 5, 5, 5, 5, 0
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};
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/// <summary>
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/// Copy offsets for distance codes 0..29
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/// </summary>
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static readonly int[] CPDIST = {
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1, 2, 3, 4, 5, 7, 9, 13, 17, 25, 33, 49, 65, 97, 129, 193,
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257, 385, 513, 769, 1025, 1537, 2049, 3073, 4097, 6145,
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8193, 12289, 16385, 24577
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};
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/// <summary>
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/// Extra bits for distance codes
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/// </summary>
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static readonly int[] CPDEXT = {
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0, 0, 0, 0, 1, 1, 2, 2, 3, 3, 4, 4, 5, 5, 6, 6,
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7, 7, 8, 8, 9, 9, 10, 10, 11, 11,
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12, 12, 13, 13
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};
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/// <summary>
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/// These are the possible states for an inflater
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/// </summary>
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const int DECODE_HEADER = 0;
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const int DECODE_DICT = 1;
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const int DECODE_BLOCKS = 2;
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const int DECODE_STORED_LEN1 = 3;
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const int DECODE_STORED_LEN2 = 4;
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const int DECODE_STORED = 5;
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const int DECODE_DYN_HEADER = 6;
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const int DECODE_HUFFMAN = 7;
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const int DECODE_HUFFMAN_LENBITS = 8;
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const int DECODE_HUFFMAN_DIST = 9;
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const int DECODE_HUFFMAN_DISTBITS = 10;
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const int DECODE_CHKSUM = 11;
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const int FINISHED = 12;
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#endregion
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#region Instance Fields
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/// <summary>
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/// This variable contains the current state.
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/// </summary>
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int mode;
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/// <summary>
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/// The adler checksum of the dictionary or of the decompressed
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/// stream, as it is written in the header resp. footer of the
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/// compressed stream.
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/// Only valid if mode is DECODE_DICT or DECODE_CHKSUM.
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/// </summary>
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int readAdler;
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/// <summary>
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/// The number of bits needed to complete the current state. This
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/// is valid, if mode is DECODE_DICT, DECODE_CHKSUM,
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/// DECODE_HUFFMAN_LENBITS or DECODE_HUFFMAN_DISTBITS.
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/// </summary>
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int neededBits;
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int repLength;
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int repDist;
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int uncomprLen;
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/// <summary>
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/// True, if the last block flag was set in the last block of the
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/// inflated stream. This means that the stream ends after the
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/// current block.
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/// </summary>
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bool isLastBlock;
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/// <summary>
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/// The total number of inflated bytes.
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/// </summary>
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long totalOut;
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/// <summary>
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/// The total number of bytes set with setInput(). This is not the
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/// value returned by the TotalIn property, since this also includes the
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/// unprocessed input.
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/// </summary>
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long totalIn;
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/// <summary>
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/// This variable stores the noHeader flag that was given to the constructor.
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/// True means, that the inflated stream doesn't contain a Zlib header or
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/// footer.
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/// </summary>
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bool noHeader;
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StreamManipulator input;
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OutputWindow outputWindow;
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InflaterDynHeader dynHeader;
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InflaterHuffmanTree litlenTree, distTree;
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Adler32 adler;
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#endregion
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#region Constructors
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/// <summary>
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/// Creates a new inflater or RFC1951 decompressor
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/// RFC1950/Zlib headers and footers will be expected in the input data
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/// </summary>
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public Inflater() : this(false)
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{
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}
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/// <summary>
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/// Creates a new inflater.
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/// </summary>
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/// <param name="noHeader">
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/// True if no RFC1950/Zlib header and footer fields are expected in the input data
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///
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/// This is used for GZIPed/Zipped input.
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///
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/// For compatibility with
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/// Sun JDK you should provide one byte of input more than needed in
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/// this case.
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/// </param>
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public Inflater(bool noHeader)
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{
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this.noHeader = noHeader;
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this.adler = new Adler32();
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input = new StreamManipulator();
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outputWindow = new OutputWindow();
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mode = noHeader ? DECODE_BLOCKS : DECODE_HEADER;
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}
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#endregion
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/// <summary>
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/// Resets the inflater so that a new stream can be decompressed. All
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/// pending input and output will be discarded.
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/// </summary>
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public void Reset()
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{
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mode = noHeader ? DECODE_BLOCKS : DECODE_HEADER;
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totalIn = 0;
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totalOut = 0;
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input.Reset();
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outputWindow.Reset();
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dynHeader = null;
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litlenTree = null;
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distTree = null;
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isLastBlock = false;
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adler.Reset();
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}
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/// <summary>
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/// Decodes a zlib/RFC1950 header.
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/// </summary>
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/// <returns>
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/// False if more input is needed.
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/// </returns>
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/// <exception cref="SharpZipBaseException">
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/// The header is invalid.
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/// </exception>
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private bool DecodeHeader()
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{
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int header = input.PeekBits(16);
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if (header < 0) {
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return false;
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}
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input.DropBits(16);
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// The header is written in "wrong" byte order
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header = ((header << 8) | (header >> 8)) & 0xffff;
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if (header % 31 != 0) {
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throw new SharpZipBaseException("Header checksum illegal");
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}
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if ((header & 0x0f00) != (Deflater.DEFLATED << 8)) {
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throw new SharpZipBaseException("Compression Method unknown");
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}
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/* Maximum size of the backwards window in bits.
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* We currently ignore this, but we could use it to make the
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* inflater window more space efficient. On the other hand the
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* full window (15 bits) is needed most times, anyway.
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int max_wbits = ((header & 0x7000) >> 12) + 8;
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*/
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if ((header & 0x0020) == 0) { // Dictionary flag?
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mode = DECODE_BLOCKS;
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} else {
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mode = DECODE_DICT;
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neededBits = 32;
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}
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return true;
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}
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/// <summary>
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/// Decodes the dictionary checksum after the deflate header.
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/// </summary>
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/// <returns>
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/// False if more input is needed.
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/// </returns>
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private bool DecodeDict()
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{
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while (neededBits > 0) {
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int dictByte = input.PeekBits(8);
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if (dictByte < 0) {
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return false;
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}
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input.DropBits(8);
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readAdler = (readAdler << 8) | dictByte;
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neededBits -= 8;
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}
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return false;
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}
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/// <summary>
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/// Decodes the huffman encoded symbols in the input stream.
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/// </summary>
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/// <returns>
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/// false if more input is needed, true if output window is
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/// full or the current block ends.
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/// </returns>
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/// <exception cref="SharpZipBaseException">
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/// if deflated stream is invalid.
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/// </exception>
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private bool DecodeHuffman()
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{
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int free = outputWindow.GetFreeSpace();
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while (free >= 258)
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{
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int symbol;
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switch (mode)
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{
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case DECODE_HUFFMAN:
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// This is the inner loop so it is optimized a bit
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while (((symbol = litlenTree.GetSymbol(input)) & ~0xff) == 0)
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{
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outputWindow.Write(symbol);
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if (--free < 258)
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{
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return true;
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}
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}
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if (symbol < 257)
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{
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if (symbol < 0)
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{
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return false;
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}
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else
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{
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// symbol == 256: end of block
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distTree = null;
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litlenTree = null;
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mode = DECODE_BLOCKS;
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return true;
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}
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}
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try
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{
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repLength = CPLENS[symbol - 257];
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neededBits = CPLEXT[symbol - 257];
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}
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catch (Exception)
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{
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throw new SharpZipBaseException("Illegal rep length code");
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}
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goto case DECODE_HUFFMAN_LENBITS; // fall through
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case DECODE_HUFFMAN_LENBITS:
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if (neededBits > 0)
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{
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mode = DECODE_HUFFMAN_LENBITS;
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int i = input.PeekBits(neededBits);
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if (i < 0)
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{
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return false;
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}
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input.DropBits(neededBits);
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repLength += i;
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}
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mode = DECODE_HUFFMAN_DIST;
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goto case DECODE_HUFFMAN_DIST; // fall through
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case DECODE_HUFFMAN_DIST:
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symbol = distTree.GetSymbol(input);
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if (symbol < 0)
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{
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return false;
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}
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try
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{
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repDist = CPDIST[symbol];
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neededBits = CPDEXT[symbol];
|
}
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catch (Exception)
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{
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throw new SharpZipBaseException("Illegal rep dist code");
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}
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goto case DECODE_HUFFMAN_DISTBITS; // fall through
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case DECODE_HUFFMAN_DISTBITS:
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if (neededBits > 0)
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{
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mode = DECODE_HUFFMAN_DISTBITS;
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int i = input.PeekBits(neededBits);
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if (i < 0)
|
{
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return false;
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}
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input.DropBits(neededBits);
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repDist += i;
|
}
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outputWindow.Repeat(repLength, repDist);
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free -= repLength;
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mode = DECODE_HUFFMAN;
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break;
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default:
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throw new SharpZipBaseException("Inflater unknown mode");
|
}
|
}
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return true;
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}
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/// <summary>
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/// Decodes the adler checksum after the deflate stream.
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/// </summary>
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/// <returns>
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/// false if more input is needed.
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/// </returns>
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/// <exception cref="SharpZipBaseException">
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/// If checksum doesn't match.
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/// </exception>
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private bool DecodeChksum()
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{
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while (neededBits > 0) {
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int chkByte = input.PeekBits(8);
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if (chkByte < 0) {
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return false;
|
}
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input.DropBits(8);
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readAdler = (readAdler << 8) | chkByte;
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neededBits -= 8;
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}
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if ((int) adler.Value != readAdler) {
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throw new SharpZipBaseException("Adler chksum doesn't match: " + (int)adler.Value + " vs. " + readAdler);
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}
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mode = FINISHED;
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return false;
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}
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/// <summary>
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/// Decodes the deflated stream.
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/// </summary>
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/// <returns>
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/// false if more input is needed, or if finished.
|
/// </returns>
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/// <exception cref="SharpZipBaseException">
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/// if deflated stream is invalid.
|
/// </exception>
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private bool Decode()
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{
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switch (mode) {
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case DECODE_HEADER:
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return DecodeHeader();
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case DECODE_DICT:
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return DecodeDict();
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case DECODE_CHKSUM:
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return DecodeChksum();
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|
case DECODE_BLOCKS:
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if (isLastBlock) {
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if (noHeader) {
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mode = FINISHED;
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return false;
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} else {
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input.SkipToByteBoundary();
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neededBits = 32;
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mode = DECODE_CHKSUM;
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return true;
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}
|
}
|
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int type = input.PeekBits(3);
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if (type < 0) {
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return false;
|
}
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input.DropBits(3);
|
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if ((type & 1) != 0) {
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isLastBlock = true;
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}
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switch (type >> 1){
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case DeflaterConstants.STORED_BLOCK:
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input.SkipToByteBoundary();
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mode = DECODE_STORED_LEN1;
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break;
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case DeflaterConstants.STATIC_TREES:
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litlenTree = InflaterHuffmanTree.defLitLenTree;
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distTree = InflaterHuffmanTree.defDistTree;
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mode = DECODE_HUFFMAN;
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break;
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case DeflaterConstants.DYN_TREES:
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dynHeader = new InflaterDynHeader();
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mode = DECODE_DYN_HEADER;
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break;
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default:
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throw new SharpZipBaseException("Unknown block type " + type);
|
}
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return true;
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case DECODE_STORED_LEN1:
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{
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if ((uncomprLen = input.PeekBits(16)) < 0) {
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return false;
|
}
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input.DropBits(16);
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mode = DECODE_STORED_LEN2;
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}
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goto case DECODE_STORED_LEN2; // fall through
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case DECODE_STORED_LEN2:
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{
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int nlen = input.PeekBits(16);
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if (nlen < 0) {
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return false;
|
}
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input.DropBits(16);
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if (nlen != (uncomprLen ^ 0xffff)) {
|
throw new SharpZipBaseException("broken uncompressed block");
|
}
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mode = DECODE_STORED;
|
}
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goto case DECODE_STORED; // fall through
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case DECODE_STORED:
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{
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int more = outputWindow.CopyStored(input, uncomprLen);
|
uncomprLen -= more;
|
if (uncomprLen == 0) {
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mode = DECODE_BLOCKS;
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return true;
|
}
|
return !input.IsNeedingInput;
|
}
|
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case DECODE_DYN_HEADER:
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if (!dynHeader.Decode(input)) {
|
return false;
|
}
|
|
litlenTree = dynHeader.BuildLitLenTree();
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distTree = dynHeader.BuildDistTree();
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mode = DECODE_HUFFMAN;
|
goto case DECODE_HUFFMAN; // fall through
|
|
case DECODE_HUFFMAN:
|
case DECODE_HUFFMAN_LENBITS:
|
case DECODE_HUFFMAN_DIST:
|
case DECODE_HUFFMAN_DISTBITS:
|
return DecodeHuffman();
|
|
case FINISHED:
|
return false;
|
|
default:
|
throw new SharpZipBaseException("Inflater.Decode unknown mode");
|
}
|
}
|
|
/// <summary>
|
/// Sets the preset dictionary. This should only be called, if
|
/// needsDictionary() returns true and it should set the same
|
/// dictionary, that was used for deflating. The getAdler()
|
/// function returns the checksum of the dictionary needed.
|
/// </summary>
|
/// <param name="buffer">
|
/// The dictionary.
|
/// </param>
|
public void SetDictionary(byte[] buffer)
|
{
|
SetDictionary(buffer, 0, buffer.Length);
|
}
|
|
/// <summary>
|
/// Sets the preset dictionary. This should only be called, if
|
/// needsDictionary() returns true and it should set the same
|
/// dictionary, that was used for deflating. The getAdler()
|
/// function returns the checksum of the dictionary needed.
|
/// </summary>
|
/// <param name="buffer">
|
/// The dictionary.
|
/// </param>
|
/// <param name="index">
|
/// The index into buffer where the dictionary starts.
|
/// </param>
|
/// <param name="count">
|
/// The number of bytes in the dictionary.
|
/// </param>
|
/// <exception cref="System.InvalidOperationException">
|
/// No dictionary is needed.
|
/// </exception>
|
/// <exception cref="SharpZipBaseException">
|
/// The adler checksum for the buffer is invalid
|
/// </exception>
|
public void SetDictionary(byte[] buffer, int index, int count)
|
{
|
if ( buffer == null ) {
|
throw new ArgumentNullException("buffer");
|
}
|
|
if ( index < 0 ) {
|
throw new ArgumentOutOfRangeException("index");
|
}
|
|
if ( count < 0 ) {
|
throw new ArgumentOutOfRangeException("count");
|
}
|
|
if (!IsNeedingDictionary) {
|
throw new InvalidOperationException("Dictionary is not needed");
|
}
|
|
adler.Update(buffer, index, count);
|
|
if ((int)adler.Value != readAdler) {
|
throw new SharpZipBaseException("Wrong adler checksum");
|
}
|
adler.Reset();
|
outputWindow.CopyDict(buffer, index, count);
|
mode = DECODE_BLOCKS;
|
}
|
|
/// <summary>
|
/// Sets the input. This should only be called, if needsInput()
|
/// returns true.
|
/// </summary>
|
/// <param name="buffer">
|
/// the input.
|
/// </param>
|
public void SetInput(byte[] buffer)
|
{
|
SetInput(buffer, 0, buffer.Length);
|
}
|
|
/// <summary>
|
/// Sets the input. This should only be called, if needsInput()
|
/// returns true.
|
/// </summary>
|
/// <param name="buffer">
|
/// The source of input data
|
/// </param>
|
/// <param name="index">
|
/// The index into buffer where the input starts.
|
/// </param>
|
/// <param name="count">
|
/// The number of bytes of input to use.
|
/// </param>
|
/// <exception cref="System.InvalidOperationException">
|
/// No input is needed.
|
/// </exception>
|
/// <exception cref="System.ArgumentOutOfRangeException">
|
/// The index and/or count are wrong.
|
/// </exception>
|
public void SetInput(byte[] buffer, int index, int count)
|
{
|
input.SetInput(buffer, index, count);
|
totalIn += (long)count;
|
}
|
|
/// <summary>
|
/// Inflates the compressed stream to the output buffer. If this
|
/// returns 0, you should check, whether IsNeedingDictionary(),
|
/// IsNeedingInput() or IsFinished() returns true, to determine why no
|
/// further output is produced.
|
/// </summary>
|
/// <param name="buffer">
|
/// the output buffer.
|
/// </param>
|
/// <returns>
|
/// The number of bytes written to the buffer, 0 if no further
|
/// output can be produced.
|
/// </returns>
|
/// <exception cref="System.ArgumentOutOfRangeException">
|
/// if buffer has length 0.
|
/// </exception>
|
/// <exception cref="System.FormatException">
|
/// if deflated stream is invalid.
|
/// </exception>
|
public int Inflate(byte[] buffer)
|
{
|
if ( buffer == null )
|
{
|
throw new ArgumentNullException("buffer");
|
}
|
|
return Inflate(buffer, 0, buffer.Length);
|
}
|
|
/// <summary>
|
/// Inflates the compressed stream to the output buffer. If this
|
/// returns 0, you should check, whether needsDictionary(),
|
/// needsInput() or finished() returns true, to determine why no
|
/// further output is produced.
|
/// </summary>
|
/// <param name="buffer">
|
/// the output buffer.
|
/// </param>
|
/// <param name="offset">
|
/// the offset in buffer where storing starts.
|
/// </param>
|
/// <param name="count">
|
/// the maximum number of bytes to output.
|
/// </param>
|
/// <returns>
|
/// the number of bytes written to the buffer, 0 if no further output can be produced.
|
/// </returns>
|
/// <exception cref="System.ArgumentOutOfRangeException">
|
/// if count is less than 0.
|
/// </exception>
|
/// <exception cref="System.ArgumentOutOfRangeException">
|
/// if the index and / or count are wrong.
|
/// </exception>
|
/// <exception cref="System.FormatException">
|
/// if deflated stream is invalid.
|
/// </exception>
|
public int Inflate(byte[] buffer, int offset, int count)
|
{
|
if ( buffer == null )
|
{
|
throw new ArgumentNullException("buffer");
|
}
|
|
if ( count < 0 ) {
|
#if NETCF_1_0
|
throw new ArgumentOutOfRangeException("count");
|
#else
|
throw new ArgumentOutOfRangeException("count", "count cannot be negative");
|
#endif
|
}
|
|
if ( offset < 0 ) {
|
#if NETCF_1_0
|
throw new ArgumentOutOfRangeException("offset");
|
#else
|
throw new ArgumentOutOfRangeException("offset", "offset cannot be negative");
|
#endif
|
}
|
|
if ( offset + count > buffer.Length ) {
|
throw new ArgumentException("count exceeds buffer bounds");
|
}
|
|
// Special case: count may be zero
|
if (count == 0)
|
{
|
if (!IsFinished) { // -jr- 08-Nov-2003 INFLATE_BUG fix..
|
Decode();
|
}
|
return 0;
|
}
|
|
int bytesCopied = 0;
|
|
do {
|
if (mode != DECODE_CHKSUM) {
|
/* Don't give away any output, if we are waiting for the
|
* checksum in the input stream.
|
*
|
* With this trick we have always:
|
* IsNeedingInput() and not IsFinished()
|
* implies more output can be produced.
|
*/
|
int more = outputWindow.CopyOutput(buffer, offset, count);
|
if ( more > 0 ) {
|
adler.Update(buffer, offset, more);
|
offset += more;
|
bytesCopied += more;
|
totalOut += (long)more;
|
count -= more;
|
if (count == 0) {
|
return bytesCopied;
|
}
|
}
|
}
|
} while (Decode() || ((outputWindow.GetAvailable() > 0) && (mode != DECODE_CHKSUM)));
|
return bytesCopied;
|
}
|
|
/// <summary>
|
/// Returns true, if the input buffer is empty.
|
/// You should then call setInput().
|
/// NOTE: This method also returns true when the stream is finished.
|
/// </summary>
|
public bool IsNeedingInput {
|
get {
|
return input.IsNeedingInput;
|
}
|
}
|
|
/// <summary>
|
/// Returns true, if a preset dictionary is needed to inflate the input.
|
/// </summary>
|
public bool IsNeedingDictionary {
|
get {
|
return mode == DECODE_DICT && neededBits == 0;
|
}
|
}
|
|
/// <summary>
|
/// Returns true, if the inflater has finished. This means, that no
|
/// input is needed and no output can be produced.
|
/// </summary>
|
public bool IsFinished {
|
get {
|
return mode == FINISHED && outputWindow.GetAvailable() == 0;
|
}
|
}
|
|
/// <summary>
|
/// Gets the adler checksum. This is either the checksum of all
|
/// uncompressed bytes returned by inflate(), or if needsDictionary()
|
/// returns true (and thus no output was yet produced) this is the
|
/// adler checksum of the expected dictionary.
|
/// </summary>
|
/// <returns>
|
/// the adler checksum.
|
/// </returns>
|
public int Adler {
|
get {
|
return IsNeedingDictionary ? readAdler : (int) adler.Value;
|
}
|
}
|
|
/// <summary>
|
/// Gets the total number of output bytes returned by Inflate().
|
/// </summary>
|
/// <returns>
|
/// the total number of output bytes.
|
/// </returns>
|
public long TotalOut {
|
get {
|
return totalOut;
|
}
|
}
|
|
/// <summary>
|
/// Gets the total number of processed compressed input bytes.
|
/// </summary>
|
/// <returns>
|
/// The total number of bytes of processed input bytes.
|
/// </returns>
|
public long TotalIn {
|
get {
|
return totalIn - (long)RemainingInput;
|
}
|
}
|
|
/// <summary>
|
/// Gets the number of unprocessed input bytes. Useful, if the end of the
|
/// stream is reached and you want to further process the bytes after
|
/// the deflate stream.
|
/// </summary>
|
/// <returns>
|
/// The number of bytes of the input which have not been processed.
|
/// </returns>
|
public int RemainingInput {
|
// TODO: This should be a long?
|
get {
|
return input.AvailableBytes;
|
}
|
}
|
}
|
}
|
