1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
|
//
// � Copyright Henrik Ravn 2004
//
// Use, modification and distribution are subject to the Boost Software License, Version 1.0.
// (See accompanying file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
//
using System;
using System.Diagnostics;
using System.Runtime.InteropServices;
namespace DotZLib
{
/// <summary>
/// Implements a data compressor, using the deflate algorithm in the ZLib dll
/// </summary>
public sealed class Deflater : CodecBase
{
#region Dll imports
[DllImport("ZLIB1.dll", CallingConvention=CallingConvention.Cdecl, CharSet=CharSet.Ansi)]
private static extern int deflateInit_(ref ZStream sz, int level, string vs, int size);
[DllImport("ZLIB1.dll", CallingConvention=CallingConvention.Cdecl)]
private static extern int deflate(ref ZStream sz, int flush);
[DllImport("ZLIB1.dll", CallingConvention=CallingConvention.Cdecl)]
private static extern int deflateReset(ref ZStream sz);
[DllImport("ZLIB1.dll", CallingConvention=CallingConvention.Cdecl)]
private static extern int deflateEnd(ref ZStream sz);
#endregion
/// <summary>
/// Constructs an new instance of the <c>Deflater</c>
/// </summary>
/// <param name="level">The compression level to use for this <c>Deflater</c></param>
public Deflater(CompressLevel level) : base()
{
int retval = deflateInit_(ref _ztream, (int)level, Info.Version, Marshal.SizeOf(_ztream));
if (retval != 0)
throw new ZLibException(retval, "Could not initialize deflater");
resetOutput();
}
/// <summary>
/// Adds more data to the codec to be processed.
/// </summary>
/// <param name="data">Byte array containing the data to be added to the codec</param>
/// <param name="offset">The index of the first byte to add from <c>data</c></param>
/// <param name="count">The number of bytes to add</param>
/// <remarks>Adding data may, or may not, raise the <c>DataAvailable</c> event</remarks>
public override void Add(byte[] data, int offset, int count)
{
if (data == null) throw new ArgumentNullException();
if (offset < 0 || count < 0) throw new ArgumentOutOfRangeException();
if ((offset+count) > data.Length) throw new ArgumentException();
int total = count;
int inputIndex = offset;
int err = 0;
while (err >= 0 && inputIndex < total)
{
copyInput(data, inputIndex, Math.Min(total - inputIndex, kBufferSize));
while (err >= 0 && _ztream.avail_in > 0)
{
err = deflate(ref _ztream, (int)FlushTypes.None);
if (err == 0)
while (_ztream.avail_out == 0)
{
OnDataAvailable();
err = deflate(ref _ztream, (int)FlushTypes.None);
}
inputIndex += (int)_ztream.total_in;
}
}
setChecksum( _ztream.adler );
}
/// <summary>
/// Finishes up any pending data that needs to be processed and handled.
/// </summary>
public override void Finish()
{
int err;
do
{
err = deflate(ref _ztream, (int)FlushTypes.Finish);
OnDataAvailable();
}
while (err == 0);
setChecksum( _ztream.adler );
deflateReset(ref _ztream);
resetOutput();
}
/// <summary>
/// Closes the internal zlib deflate stream
/// </summary>
protected override void CleanUp() { deflateEnd(ref _ztream); }
}
}
|
