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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)]
deflateInit_(ref ZStream sz, int level, string vs, int size)22         private static extern int deflateInit_(ref ZStream sz, int level, string vs, int size);
23 
24         [DllImport("ZLIB1.dll", CallingConvention=CallingConvention.Cdecl)]
deflate(ref ZStream sz, int flush)25         private static extern int deflate(ref ZStream sz, int flush);
26 
27         [DllImport("ZLIB1.dll", CallingConvention=CallingConvention.Cdecl)]
deflateReset(ref ZStream sz)28         private static extern int deflateReset(ref ZStream sz);
29 
30         [DllImport("ZLIB1.dll", CallingConvention=CallingConvention.Cdecl)]
deflateEnd(ref ZStream sz)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>
Deflater(CompressLevel level)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>
Add(byte[] data, int offset, int count)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>
Finish()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>
CleanUp()103         protected override void CleanUp() { deflateEnd(ref _ztream); }
104 
105     }
106 }
107