zlib/contrib/dotzlib/DotZLib/Inflater.cs

   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 }