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      1 //
      2 //  Copyright Henrik Ravn 2004
      3 //
      4 // Use, modification and distribution are subject to the Boost Software License, Version 1.0.
      5 // (See accompanying file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
      6 //
      7 
      8 using System;
      9 using System.Diagnostics;
     10 using System.Runtime.InteropServices;
     11 
     12 namespace DotZLib
     13 {
     14 
     15     /// <summary>
     16     /// Implements a data decompressor, using the inflate algorithm in the ZLib dll
     17     /// </summary>
     18     public class Inflater : CodecBase
     19 	{
     20         #region Dll imports
     21         [DllImport("ZLIB1.dll", CallingConvention=CallingConvention.Cdecl, CharSet=CharSet.Ansi)]
     22         private static extern int inflateInit_(ref ZStream sz, string vs, int size);
     23 
     24         [DllImport("ZLIB1.dll", CallingConvention=CallingConvention.Cdecl)]
     25         private static extern int inflate(ref ZStream sz, int flush);
     26 
     27         [DllImport("ZLIB1.dll", CallingConvention=CallingConvention.Cdecl)]
     28         private static extern int inflateReset(ref ZStream sz);
     29 
     30         [DllImport("ZLIB1.dll", CallingConvention=CallingConvention.Cdecl)]
     31         private static extern int inflateEnd(ref ZStream sz);
     32         #endregion
     33 
     34         /// <summary>
     35         /// Constructs an new instance of the <c>Inflater</c>
     36         /// </summary>
     37         public Inflater() : base()
     38 		{
     39             int retval = inflateInit_(ref _ztream, Info.Version, Marshal.SizeOf(_ztream));
     40             if (retval != 0)
     41                 throw new ZLibException(retval, "Could not initialize inflater");
     42 
     43             resetOutput();
     44         }
     45 
     46 
     47         /// <summary>
     48         /// Adds more data to the codec to be processed.
     49         /// </summary>
     50         /// <param name="data">Byte array containing the data to be added to the codec</param>
     51         /// <param name="offset">The index of the first byte to add from <c>data</c></param>
     52         /// <param name="count">The number of bytes to add</param>
     53         /// <remarks>Adding data may, or may not, raise the <c>DataAvailable</c> event</remarks>
     54         public override void Add(byte[] data, int offset, int count)
     55         {
     56             if (data == null) throw new ArgumentNullException();
     57             if (offset < 0 || count < 0) throw new ArgumentOutOfRangeException();
     58             if ((offset+count) > data.Length) throw new ArgumentException();
     59 
     60             int total = count;
     61             int inputIndex = offset;
     62             int err = 0;
     63 
     64             while (err >= 0 && inputIndex < total)
     65             {
     66                 copyInput(data, inputIndex, Math.Min(total - inputIndex, kBufferSize));
     67                 err = inflate(ref _ztream, (int)FlushTypes.None);
     68                 if (err == 0)
     69                     while (_ztream.avail_out == 0)
     70                     {
     71                         OnDataAvailable();
     72                         err = inflate(ref _ztream, (int)FlushTypes.None);
     73                     }
     74 
     75                 inputIndex += (int)_ztream.total_in;
     76             }
     77             setChecksum( _ztream.adler );
     78         }
     79 
     80 
     81         /// <summary>
     82         /// Finishes up any pending data that needs to be processed and handled.
     83         /// </summary>
     84         public override void Finish()
     85         {
     86             int err;
     87             do
     88             {
     89                 err = inflate(ref _ztream, (int)FlushTypes.Finish);
     90                 OnDataAvailable();
     91             }
     92             while (err == 0);
     93             setChecksum( _ztream.adler );
     94             inflateReset(ref _ztream);
     95             resetOutput();
     96         }
     97 
     98         /// <summary>
     99         /// Closes the internal zlib inflate stream
    100         /// </summary>
    101         protected override void CleanUp() { inflateEnd(ref _ztream); }
    102 
    103 
    104 	}
    105 }
    106