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
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
|
//
// © 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.Runtime.InteropServices;
using System.Text;
namespace DotZLib
{
#region ChecksumGeneratorBase
/// <summary>
/// Implements the common functionality needed for all <see cref="ChecksumGenerator"/>s
/// </summary>
/// <example></example>
public abstract class ChecksumGeneratorBase : ChecksumGenerator
{
/// <summary>
/// The value of the current checksum
/// </summary>
protected uint _current;
/// <summary>
/// Initializes a new instance of the checksum generator base - the current checksum is
/// set to zero
/// </summary>
public ChecksumGeneratorBase()
{
_current = 0;
}
/// <summary>
/// Initializes a new instance of the checksum generator basewith a specified value
/// </summary>
/// <param name="initialValue">The value to set the current checksum to</param>
public ChecksumGeneratorBase(uint initialValue)
{
_current = initialValue;
}
/// <summary>
/// Resets the current checksum to zero
/// </summary>
public void Reset() { _current = 0; }
/// <summary>
/// Gets the current checksum value
/// </summary>
public uint Value { get { return _current; } }
/// <summary>
/// Updates the current checksum with part of an array of bytes
/// </summary>
/// <param name="data">The data to update the checksum with</param>
/// <param name="offset">Where in <c>data</c> to start updating</param>
/// <param name="count">The number of bytes from <c>data</c> to use</param>
/// <exception cref="ArgumentException">The sum of offset and count is larger than the length of <c>data</c></exception>
/// <exception cref="NullReferenceException"><c>data</c> is a null reference</exception>
/// <exception cref="ArgumentOutOfRangeException">Offset or count is negative.</exception>
/// <remarks>All the other <c>Update</c> methods are implmeneted in terms of this one.
/// This is therefore the only method a derived class has to implement</remarks>
public abstract void Update(byte[] data, int offset, int count);
/// <summary>
/// Updates the current checksum with an array of bytes.
/// </summary>
/// <param name="data">The data to update the checksum with</param>
public void Update(byte[] data)
{
Update(data, 0, data.Length);
}
/// <summary>
/// Updates the current checksum with the data from a string
/// </summary>
/// <param name="data">The string to update the checksum with</param>
/// <remarks>The characters in the string are converted by the UTF-8 encoding</remarks>
public void Update(string data)
{
Update(Encoding.UTF8.GetBytes(data));
}
/// <summary>
/// Updates the current checksum with the data from a string, using a specific encoding
/// </summary>
/// <param name="data">The string to update the checksum with</param>
/// <param name="encoding">The encoding to use</param>
public void Update(string data, Encoding encoding)
{
Update(encoding.GetBytes(data));
}
}
#endregion
#region CRC32
/// <summary>
/// Implements a CRC32 checksum generator
/// </summary>
public sealed class CRC32Checksum : ChecksumGeneratorBase
{
#region DLL imports
[DllImport("ZLIB1.dll", CallingConvention=CallingConvention.Cdecl)]
private static extern uint crc32(uint crc, int data, uint length);
#endregion
/// <summary>
/// Initializes a new instance of the CRC32 checksum generator
/// </summary>
public CRC32Checksum() : base() {}
/// <summary>
/// Initializes a new instance of the CRC32 checksum generator with a specified value
/// </summary>
/// <param name="initialValue">The value to set the current checksum to</param>
public CRC32Checksum(uint initialValue) : base(initialValue) {}
/// <summary>
/// Updates the current checksum with part of an array of bytes
/// </summary>
/// <param name="data">The data to update the checksum with</param>
/// <param name="offset">Where in <c>data</c> to start updating</param>
/// <param name="count">The number of bytes from <c>data</c> to use</param>
/// <exception cref="ArgumentException">The sum of offset and count is larger than the length of <c>data</c></exception>
/// <exception cref="NullReferenceException"><c>data</c> is a null reference</exception>
/// <exception cref="ArgumentOutOfRangeException">Offset or count is negative.</exception>
public override void Update(byte[] data, int offset, int count)
{
if (offset < 0 || count < 0) throw new ArgumentOutOfRangeException();
if ((offset+count) > data.Length) throw new ArgumentException();
GCHandle hData = GCHandle.Alloc(data, GCHandleType.Pinned);
try
{
_current = crc32(_current, hData.AddrOfPinnedObject().ToInt32()+offset, (uint)count);
}
finally
{
hData.Free();
}
}
}
#endregion
#region Adler
/// <summary>
/// Implements a checksum generator that computes the Adler checksum on data
/// </summary>
public sealed class AdlerChecksum : ChecksumGeneratorBase
{
#region DLL imports
[DllImport("ZLIB1.dll", CallingConvention=CallingConvention.Cdecl)]
private static extern uint adler32(uint adler, int data, uint length);
#endregion
/// <summary>
/// Initializes a new instance of the Adler checksum generator
/// </summary>
public AdlerChecksum() : base() {}
/// <summary>
/// Initializes a new instance of the Adler checksum generator with a specified value
/// </summary>
/// <param name="initialValue">The value to set the current checksum to</param>
public AdlerChecksum(uint initialValue) : base(initialValue) {}
/// <summary>
/// Updates the current checksum with part of an array of bytes
/// </summary>
/// <param name="data">The data to update the checksum with</param>
/// <param name="offset">Where in <c>data</c> to start updating</param>
/// <param name="count">The number of bytes from <c>data</c> to use</param>
/// <exception cref="ArgumentException">The sum of offset and count is larger than the length of <c>data</c></exception>
/// <exception cref="NullReferenceException"><c>data</c> is a null reference</exception>
/// <exception cref="ArgumentOutOfRangeException">Offset or count is negative.</exception>
public override void Update(byte[] data, int offset, int count)
{
if (offset < 0 || count < 0) throw new ArgumentOutOfRangeException();
if ((offset+count) > data.Length) throw new ArgumentException();
GCHandle hData = GCHandle.Alloc(data, GCHandleType.Pinned);
try
{
_current = adler32(_current, hData.AddrOfPinnedObject().ToInt32()+offset, (uint)count);
}
finally
{
hData.Free();
}
}
}
#endregion
}
|
