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)]
inflateInit_(ref ZStream sz, string vs, int size)22         private static extern int inflateInit_(ref ZStream sz, string vs, int size);
23 
24         [DllImport("ZLIB1.dll", CallingConvention=CallingConvention.Cdecl)]
inflate(ref ZStream sz, int flush)25         private static extern int inflate(ref ZStream sz, int flush);
26 
27         [DllImport("ZLIB1.dll", CallingConvention=CallingConvention.Cdecl)]
inflateReset(ref ZStream sz)28         private static extern int inflateReset(ref ZStream sz);
29 
30         [DllImport("ZLIB1.dll", CallingConvention=CallingConvention.Cdecl)]
inflateEnd(ref ZStream sz)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>
Inflater()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>
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                 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>
Finish()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>
CleanUp()101         protected override void CleanUp() { inflateEnd(ref _ztream); }
102 
103 
104 	}
105 }
106