Chris@4: //
Chris@4: // © Copyright Henrik Ravn 2004
Chris@4: //
Chris@4: // Use, modification and distribution are subject to the Boost Software License, Version 1.0.
Chris@4: // (See accompanying file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
Chris@4: //
Chris@4: 
Chris@4: using System;
Chris@4: using System.Runtime.InteropServices;
Chris@4: using System.Text;
Chris@4: 
Chris@4: 
Chris@4: namespace DotZLib
Chris@4: {
Chris@4:     #region ChecksumGeneratorBase
Chris@4:     /// <summary>
Chris@4:     /// Implements the common functionality needed for all <see cref="ChecksumGenerator"/>s
Chris@4:     /// </summary>
Chris@4:     /// <example></example>
Chris@4:     public abstract class ChecksumGeneratorBase : ChecksumGenerator
Chris@4:     {
Chris@4:         /// <summary>
Chris@4:         /// The value of the current checksum
Chris@4:         /// </summary>
Chris@4:         protected uint _current;
Chris@4: 
Chris@4:         /// <summary>
Chris@4:         /// Initializes a new instance of the checksum generator base - the current checksum is
Chris@4:         /// set to zero
Chris@4:         /// </summary>
Chris@4:         public ChecksumGeneratorBase()
Chris@4:         {
Chris@4:             _current = 0;
Chris@4:         }
Chris@4: 
Chris@4:         /// <summary>
Chris@4:         /// Initializes a new instance of the checksum generator basewith a specified value
Chris@4:         /// </summary>
Chris@4:         /// <param name="initialValue">The value to set the current checksum to</param>
Chris@4:         public ChecksumGeneratorBase(uint initialValue)
Chris@4:         {
Chris@4:             _current = initialValue;
Chris@4:         }
Chris@4: 
Chris@4:         /// <summary>
Chris@4:         /// Resets the current checksum to zero
Chris@4:         /// </summary>
Chris@4:         public void Reset() { _current = 0; }
Chris@4: 
Chris@4:         /// <summary>
Chris@4:         /// Gets the current checksum value
Chris@4:         /// </summary>
Chris@4:         public uint Value { get { return _current; } }
Chris@4: 
Chris@4:         /// <summary>
Chris@4:         /// Updates the current checksum with part of an array of bytes
Chris@4:         /// </summary>
Chris@4:         /// <param name="data">The data to update the checksum with</param>
Chris@4:         /// <param name="offset">Where in <c>data</c> to start updating</param>
Chris@4:         /// <param name="count">The number of bytes from <c>data</c> to use</param>
Chris@4:         /// <exception cref="ArgumentException">The sum of offset and count is larger than the length of <c>data</c></exception>
Chris@4:         /// <exception cref="NullReferenceException"><c>data</c> is a null reference</exception>
Chris@4:         /// <exception cref="ArgumentOutOfRangeException">Offset or count is negative.</exception>
Chris@4:         /// <remarks>All the other <c>Update</c> methods are implmeneted in terms of this one.
Chris@4:         /// This is therefore the only method a derived class has to implement</remarks>
Chris@4:         public abstract void Update(byte[] data, int offset, int count);
Chris@4: 
Chris@4:         /// <summary>
Chris@4:         /// Updates the current checksum with an array of bytes.
Chris@4:         /// </summary>
Chris@4:         /// <param name="data">The data to update the checksum with</param>
Chris@4:         public void Update(byte[] data)
Chris@4:         {
Chris@4:             Update(data, 0, data.Length);
Chris@4:         }
Chris@4: 
Chris@4:         /// <summary>
Chris@4:         /// Updates the current checksum with the data from a string
Chris@4:         /// </summary>
Chris@4:         /// <param name="data">The string to update the checksum with</param>
Chris@4:         /// <remarks>The characters in the string are converted by the UTF-8 encoding</remarks>
Chris@4:         public void Update(string data)
Chris@4:         {
Chris@4: 			Update(Encoding.UTF8.GetBytes(data));
Chris@4:         }
Chris@4: 
Chris@4:         /// <summary>
Chris@4:         /// Updates the current checksum with the data from a string, using a specific encoding
Chris@4:         /// </summary>
Chris@4:         /// <param name="data">The string to update the checksum with</param>
Chris@4:         /// <param name="encoding">The encoding to use</param>
Chris@4:         public void Update(string data, Encoding encoding)
Chris@4:         {
Chris@4:             Update(encoding.GetBytes(data));
Chris@4:         }
Chris@4: 
Chris@4:     }
Chris@4:     #endregion
Chris@4: 
Chris@4:     #region CRC32
Chris@4:     /// <summary>
Chris@4:     /// Implements a CRC32 checksum generator
Chris@4:     /// </summary>
Chris@4:     public sealed class CRC32Checksum : ChecksumGeneratorBase
Chris@4:     {
Chris@4:         #region DLL imports
Chris@4: 
Chris@4:         [DllImport("ZLIB1.dll", CallingConvention=CallingConvention.Cdecl)]
Chris@4:         private static extern uint crc32(uint crc, int data, uint length);
Chris@4: 
Chris@4:         #endregion
Chris@4: 
Chris@4:         /// <summary>
Chris@4:         /// Initializes a new instance of the CRC32 checksum generator
Chris@4:         /// </summary>
Chris@4:         public CRC32Checksum() : base() {}
Chris@4: 
Chris@4:         /// <summary>
Chris@4:         /// Initializes a new instance of the CRC32 checksum generator with a specified value
Chris@4:         /// </summary>
Chris@4:         /// <param name="initialValue">The value to set the current checksum to</param>
Chris@4:         public CRC32Checksum(uint initialValue) : base(initialValue) {}
Chris@4: 
Chris@4:         /// <summary>
Chris@4:         /// Updates the current checksum with part of an array of bytes
Chris@4:         /// </summary>
Chris@4:         /// <param name="data">The data to update the checksum with</param>
Chris@4:         /// <param name="offset">Where in <c>data</c> to start updating</param>
Chris@4:         /// <param name="count">The number of bytes from <c>data</c> to use</param>
Chris@4:         /// <exception cref="ArgumentException">The sum of offset and count is larger than the length of <c>data</c></exception>
Chris@4:         /// <exception cref="NullReferenceException"><c>data</c> is a null reference</exception>
Chris@4:         /// <exception cref="ArgumentOutOfRangeException">Offset or count is negative.</exception>
Chris@4:         public override void Update(byte[] data, int offset, int count)
Chris@4:         {
Chris@4:             if (offset < 0 || count < 0) throw new ArgumentOutOfRangeException();
Chris@4:             if ((offset+count) > data.Length) throw new ArgumentException();
Chris@4:             GCHandle hData = GCHandle.Alloc(data, GCHandleType.Pinned);
Chris@4:             try
Chris@4:             {
Chris@4:                 _current = crc32(_current, hData.AddrOfPinnedObject().ToInt32()+offset, (uint)count);
Chris@4:             }
Chris@4:             finally
Chris@4:             {
Chris@4:                 hData.Free();
Chris@4:             }
Chris@4:         }
Chris@4: 
Chris@4:     }
Chris@4:     #endregion
Chris@4: 
Chris@4:     #region Adler
Chris@4:     /// <summary>
Chris@4:     /// Implements a checksum generator that computes the Adler checksum on data
Chris@4:     /// </summary>
Chris@4:     public sealed class AdlerChecksum : ChecksumGeneratorBase
Chris@4:     {
Chris@4:         #region DLL imports
Chris@4: 
Chris@4:         [DllImport("ZLIB1.dll", CallingConvention=CallingConvention.Cdecl)]
Chris@4:         private static extern uint adler32(uint adler, int data, uint length);
Chris@4: 
Chris@4:         #endregion
Chris@4: 
Chris@4:         /// <summary>
Chris@4:         /// Initializes a new instance of the Adler checksum generator
Chris@4:         /// </summary>
Chris@4:         public AdlerChecksum() : base() {}
Chris@4: 
Chris@4:         /// <summary>
Chris@4:         /// Initializes a new instance of the Adler checksum generator with a specified value
Chris@4:         /// </summary>
Chris@4:         /// <param name="initialValue">The value to set the current checksum to</param>
Chris@4:         public AdlerChecksum(uint initialValue) : base(initialValue) {}
Chris@4: 
Chris@4:         /// <summary>
Chris@4:         /// Updates the current checksum with part of an array of bytes
Chris@4:         /// </summary>
Chris@4:         /// <param name="data">The data to update the checksum with</param>
Chris@4:         /// <param name="offset">Where in <c>data</c> to start updating</param>
Chris@4:         /// <param name="count">The number of bytes from <c>data</c> to use</param>
Chris@4:         /// <exception cref="ArgumentException">The sum of offset and count is larger than the length of <c>data</c></exception>
Chris@4:         /// <exception cref="NullReferenceException"><c>data</c> is a null reference</exception>
Chris@4:         /// <exception cref="ArgumentOutOfRangeException">Offset or count is negative.</exception>
Chris@4:         public override void Update(byte[] data, int offset, int count)
Chris@4:         {
Chris@4:             if (offset < 0 || count < 0) throw new ArgumentOutOfRangeException();
Chris@4:             if ((offset+count) > data.Length) throw new ArgumentException();
Chris@4:             GCHandle hData = GCHandle.Alloc(data, GCHandleType.Pinned);
Chris@4:             try
Chris@4:             {
Chris@4:                 _current = adler32(_current, hData.AddrOfPinnedObject().ToInt32()+offset, (uint)count);
Chris@4:             }
Chris@4:             finally
Chris@4:             {
Chris@4:                 hData.Free();
Chris@4:             }
Chris@4:         }
Chris@4: 
Chris@4:     }
Chris@4:     #endregion
Chris@4: 
Chris@4: }