release/src/router/zlib/contrib/dotzlib/DotZLib/Deflater.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 compressor, using the deflate algorithm in the ZLib dll
  17     /// </summary>
  18         public sealed class Deflater : CodecBase
  19         {
  20         #region Dll imports
  21         [DllImport("ZLIB1.dll", CallingConvention=CallingConvention.Cdecl, CharSet=CharSet.Ansi)]
  22         private static extern int deflateInit_(ref ZStream sz, int level, string vs, int size);
  23
  24         [DllImport("ZLIB1.dll", CallingConvention=CallingConvention.Cdecl)]
  25         private static extern int deflate(ref ZStream sz, int flush);
  26
  27         [DllImport("ZLIB1.dll", CallingConvention=CallingConvention.Cdecl)]
  28         private static extern int deflateReset(ref ZStream sz);
  29
  30         [DllImport("ZLIB1.dll", CallingConvention=CallingConvention.Cdecl)]
  31         private static extern int deflateEnd(ref ZStream sz);
  32         #endregion
  33
  34         /// <summary>
  35         /// Constructs an new instance of the <c>Deflater</c>
  36         /// </summary>
  37         /// <param name="level">The compression level to use for this <c>Deflater</c></param>
  38                 public Deflater(CompressLevel level) : base()
  39                 {
  40             int retval = deflateInit_(ref _ztream, (int)level, Info.Version, Marshal.SizeOf(_ztream));
  41             if (retval != 0)
  42                 throw new ZLibException(retval, "Could not initialize deflater");
  43
  44             resetOutput();
  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                 while (err >= 0 && _ztream.avail_in > 0)
  68                 {
  69                     err = deflate(ref _ztream, (int)FlushTypes.None);
  70                     if (err == 0)
  71                         while (_ztream.avail_out == 0)
  72                         {
  73                             OnDataAvailable();
  74                             err = deflate(ref _ztream, (int)FlushTypes.None);
  75                         }
  76                     inputIndex += (int)_ztream.total_in;
  77                 }
  78             }
  79             setChecksum( _ztream.adler );
  80         }
  81
  82
  83         /// <summary>
  84         /// Finishes up any pending data that needs to be processed and handled.
  85         /// </summary>
  86         public override void Finish()
  87         {
  88             int err;
  89             do
  90             {
  91                 err = deflate(ref _ztream, (int)FlushTypes.Finish);
  92                 OnDataAvailable();
  93             }
  94             while (err == 0);
  95             setChecksum( _ztream.adler );
  96             deflateReset(ref _ztream);
  97             resetOutput();
  98         }
  99
 100         /// <summary>
 101         /// Closes the internal zlib deflate stream
 102         /// </summary>
 103         protected override void CleanUp() { deflateEnd(ref _ztream); }
 104
 105     }
 106 }