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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 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 }
    107