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.Runtime.InteropServices;
10 using System.Text;
11
12
13 namespace DotZLib
14 {
15 #region ChecksumGeneratorBase
16 /// <summary>
17 /// Implements the common functionality needed for all <see cref="ChecksumGenerator"/>s
18 /// </summary>
19 /// <example></example>
20 public abstract class ChecksumGeneratorBase : ChecksumGenerator
21 {
22 /// <summary>
23 /// The value of the current checksum
24 /// </summary>
25 protected uint _current;
26
27 /// <summary>
28 /// Initializes a new instance of the checksum generator base - the current checksum is
29 /// set to zero
30 /// </summary>
31 public ChecksumGeneratorBase()
32 {
33 _current = 0;
34 }
35
36 /// <summary>
37 /// Initializes a new instance of the checksum generator basewith a specified value
38 /// </summary>
39 /// <param name="initialValue">The value to set the current checksum to</param>
40 public ChecksumGeneratorBase(uint initialValue)
41 {
42 _current = initialValue;
43 }
44
45 /// <summary>
46 /// Resets the current checksum to zero
47 /// </summary>
48 public void Reset() { _current = 0; }
49
50 /// <summary>
51 /// Gets the current checksum value
52 /// </summary>
53 public uint Value { get { return _current; } }
54
55 /// <summary>
56 /// Updates the current checksum with part of an array of bytes
57 /// </summary>
58 /// <param name="data">The data to update the checksum with</param>
59 /// <param name="offset">Where in <c>data</c> to start updating</param>
60 /// <param name="count">The number of bytes from <c>data</c> to use</param>
61 /// <exception cref="ArgumentException">The sum of offset and count is larger than the length of <c>data</c></exception>
62 /// <exception cref="NullReferenceException"><c>data</c> is a null reference</exception>
63 /// <exception cref="ArgumentOutOfRangeException">Offset or count is negative.</exception>
64 /// <remarks>All the other <c>Update</c> methods are implmeneted in terms of this one.
65 /// This is therefore the only method a derived class has to implement</remarks>
66 public abstract void Update(byte[] data, int offset, int count);
67
68 /// <summary>
69 /// Updates the current checksum with an array of bytes.
70 /// </summary>
71 /// <param name="data">The data to update the checksum with</param>
72 public void Update(byte[] data)
73 {
74 Update(data, 0, data.Length);
75 }
76
77 /// <summary>
78 /// Updates the current checksum with the data from a string
79 /// </summary>
80 /// <param name="data">The string to update the checksum with</param>
81 /// <remarks>The characters in the string are converted by the UTF-8 encoding</remarks>
82 public void Update(string data)
83 {
84 Update(Encoding.UTF8.GetBytes(data));
85 }
86
87 /// <summary>
88 /// Updates the current checksum with the data from a string, using a specific encoding
89 /// </summary>
90 /// <param name="data">The string to update the checksum with</param>
91 /// <param name="encoding">The encoding to use</param>
92 public void Update(string data, Encoding encoding)
93 {
94 Update(encoding.GetBytes(data));
95 }
96
97 }
98 #endregion
99
100 #region CRC32
101 /// <summary>
102 /// Implements a CRC32 checksum generator
103 /// </summary>
104 public sealed class CRC32Checksum : ChecksumGeneratorBase
105 {
106 #region DLL imports
107
108 [DllImport("ZLIB1.dll", CallingConvention=CallingConvention.Cdecl)]
109 private static extern uint crc32(uint crc, int data, uint length);
110
111 #endregion
112
113 /// <summary>
114 /// Initializes a new instance of the CRC32 checksum generator
115 /// </summary>
116 public CRC32Checksum() : base() {}
117
118 /// <summary>
119 /// Initializes a new instance of the CRC32 checksum generator with a specified value
120 /// </summary>
121 /// <param name="initialValue">The value to set the current checksum to</param>
122 public CRC32Checksum(uint initialValue) : base(initialValue) {}
123
124 /// <summary>
125 /// Updates the current checksum with part of an array of bytes
126 /// </summary>
127 /// <param name="data">The data to update the checksum with</param>
128 /// <param name="offset">Where in <c>data</c> to start updating</param>
129 /// <param name="count">The number of bytes from <c>data</c> to use</param>
130 /// <exception cref="ArgumentException">The sum of offset and count is larger than the length of <c>data</c></exception>
131 /// <exception cref="NullReferenceException"><c>data</c> is a null reference</exception>
132 /// <exception cref="ArgumentOutOfRangeException">Offset or count is negative.</exception>
133 public override void Update(byte[] data, int offset, int count)
134 {
135 if (offset < 0 || count < 0) throw new ArgumentOutOfRangeException();
136 if ((offset+count) > data.Length) throw new ArgumentException();
137 GCHandle hData = GCHandle.Alloc(data, GCHandleType.Pinned);
138 try
139 {
140 _current = crc32(_current, hData.AddrOfPinnedObject().ToInt32()+offset, (uint)count);
141 }
142 finally
143 {
144 hData.Free();
145 }
146 }
147
148 }
149 #endregion
150
151 #region Adler
152 /// <summary>
153 /// Implements a checksum generator that computes the Adler checksum on data
154 /// </summary>
155 public sealed class AdlerChecksum : ChecksumGeneratorBase
156 {
157 #region DLL imports
158
159 [DllImport("ZLIB1.dll", CallingConvention=CallingConvention.Cdecl)]
160 private static extern uint adler32(uint adler, int data, uint length);
161
162 #endregion
163
164 /// <summary>
165 /// Initializes a new instance of the Adler checksum generator
166 /// </summary>
167 public AdlerChecksum() : base() {}
168
169 /// <summary>
170 /// Initializes a new instance of the Adler checksum generator with a specified value
171 /// </summary>
172 /// <param name="initialValue">The value to set the current checksum to</param>
173 public AdlerChecksum(uint initialValue) : base(initialValue) {}
174
175 /// <summary>
176 /// Updates the current checksum with part of an array of bytes
177 /// </summary>
178 /// <param name="data">The data to update the checksum with</param>
179 /// <param name="offset">Where in <c>data</c> to start updating</param>
180 /// <param name="count">The number of bytes from <c>data</c> to use</param>
181 /// <exception cref="ArgumentException">The sum of offset and count is larger than the length of <c>data</c></exception>
182 /// <exception cref="NullReferenceException"><c>data</c> is a null reference</exception>
183 /// <exception cref="ArgumentOutOfRangeException">Offset or count is negative.</exception>
184 public override void Update(byte[] data, int offset, int count)
185 {
186 if (offset < 0 || count < 0) throw new ArgumentOutOfRangeException();
187 if ((offset+count) > data.Length) throw new ArgumentException();
188 GCHandle hData = GCHandle.Alloc(data, GCHandleType.Pinned);
189 try
190 {
191 _current = adler32(_current, hData.AddrOfPinnedObject().ToInt32()+offset, (uint)count);
192 }
193 finally
194 {
195 hData.Free();
196 }
197 }
198
199 }
200 #endregion
201
202 }