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: 
Chris@4: namespace DotZLib
Chris@4: {
Chris@4: 	/// <summary>
Chris@4: 	/// Implements the common functionality needed for all <see cref="Codec"/>s
Chris@4: 	/// </summary>
Chris@4: 	public abstract class CodecBase : Codec, IDisposable
Chris@4: 	{
Chris@4: 
Chris@4:         #region Data members
Chris@4: 
Chris@4:         /// <summary>
Chris@4:         /// Instance of the internal zlib buffer structure that is
Chris@4:         /// passed to all functions in the zlib dll
Chris@4:         /// </summary>
Chris@4:         internal ZStream _ztream = new ZStream();
Chris@4: 
Chris@4:         /// <summary>
Chris@4:         /// True if the object instance has been disposed, false otherwise
Chris@4:         /// </summary>
Chris@4:         protected bool _isDisposed = false;
Chris@4: 
Chris@4:         /// <summary>
Chris@4:         /// The size of the internal buffers
Chris@4:         /// </summary>
Chris@4:         protected const int kBufferSize = 16384;
Chris@4: 
Chris@4:         private byte[] _outBuffer = new byte[kBufferSize];
Chris@4:         private byte[] _inBuffer = new byte[kBufferSize];
Chris@4: 
Chris@4:         private GCHandle _hInput;
Chris@4:         private GCHandle _hOutput;
Chris@4: 
Chris@4:         private uint _checksum = 0;
Chris@4: 
Chris@4:         #endregion
Chris@4: 
Chris@4:         /// <summary>
Chris@4:         /// Initializes a new instance of the <c>CodeBase</c> class.
Chris@4:         /// </summary>
Chris@4: 		public CodecBase()
Chris@4: 		{
Chris@4:             try
Chris@4:             {
Chris@4:                 _hInput = GCHandle.Alloc(_inBuffer, GCHandleType.Pinned);
Chris@4:                 _hOutput = GCHandle.Alloc(_outBuffer, GCHandleType.Pinned);
Chris@4:             }
Chris@4:             catch (Exception)
Chris@4:             {
Chris@4:                 CleanUp(false);
Chris@4:                 throw;
Chris@4:             }
Chris@4:         }
Chris@4: 
Chris@4: 
Chris@4:         #region Codec Members
Chris@4: 
Chris@4:         /// <summary>
Chris@4:         /// Occurs when more processed data are available.
Chris@4:         /// </summary>
Chris@4:         public event DataAvailableHandler DataAvailable;
Chris@4: 
Chris@4:         /// <summary>
Chris@4:         /// Fires the <see cref="DataAvailable"/> event
Chris@4:         /// </summary>
Chris@4:         protected void OnDataAvailable()
Chris@4:         {
Chris@4:             if (_ztream.total_out > 0)
Chris@4:             {
Chris@4:                 if (DataAvailable != null)
Chris@4:                     DataAvailable( _outBuffer, 0, (int)_ztream.total_out);
Chris@4:                 resetOutput();
Chris@4:             }
Chris@4:         }
Chris@4: 
Chris@4:         /// <summary>
Chris@4:         /// Adds more data to the codec to be processed.
Chris@4:         /// </summary>
Chris@4:         /// <param name="data">Byte array containing the data to be added to the codec</param>
Chris@4:         /// <remarks>Adding data may, or may not, raise the <c>DataAvailable</c> event</remarks>
Chris@4:         public void Add(byte[] data)
Chris@4:         {
Chris@4:             Add(data,0,data.Length);
Chris@4:         }
Chris@4: 
Chris@4:         /// <summary>
Chris@4:         /// Adds more data to the codec to be processed.
Chris@4:         /// </summary>
Chris@4:         /// <param name="data">Byte array containing the data to be added to the codec</param>
Chris@4:         /// <param name="offset">The index of the first byte to add from <c>data</c></param>
Chris@4:         /// <param name="count">The number of bytes to add</param>
Chris@4:         /// <remarks>Adding data may, or may not, raise the <c>DataAvailable</c> event</remarks>
Chris@4:         /// <remarks>This must be implemented by a derived class</remarks>
Chris@4:         public abstract void Add(byte[] data, int offset, int count);
Chris@4: 
Chris@4:         /// <summary>
Chris@4:         /// Finishes up any pending data that needs to be processed and handled.
Chris@4:         /// </summary>
Chris@4:         /// <remarks>This must be implemented by a derived class</remarks>
Chris@4:         public abstract void Finish();
Chris@4: 
Chris@4:         /// <summary>
Chris@4:         /// Gets the checksum of the data that has been added so far
Chris@4:         /// </summary>
Chris@4:         public uint Checksum { get { return _checksum; } }
Chris@4: 
Chris@4:         #endregion
Chris@4: 
Chris@4:         #region Destructor & IDisposable stuff
Chris@4: 
Chris@4:         /// <summary>
Chris@4:         /// Destroys this instance
Chris@4:         /// </summary>
Chris@4:         ~CodecBase()
Chris@4:         {
Chris@4:             CleanUp(false);
Chris@4:         }
Chris@4: 
Chris@4:         /// <summary>
Chris@4:         /// Releases any unmanaged resources and calls the <see cref="CleanUp()"/> method of the derived class
Chris@4:         /// </summary>
Chris@4:         public void Dispose()
Chris@4:         {
Chris@4:             CleanUp(true);
Chris@4:         }
Chris@4: 
Chris@4:         /// <summary>
Chris@4:         /// Performs any codec specific cleanup
Chris@4:         /// </summary>
Chris@4:         /// <remarks>This must be implemented by a derived class</remarks>
Chris@4:         protected abstract void CleanUp();
Chris@4: 
Chris@4:         // performs the release of the handles and calls the dereived CleanUp()
Chris@4:         private void CleanUp(bool isDisposing)
Chris@4:         {
Chris@4:             if (!_isDisposed)
Chris@4:             {
Chris@4:                 CleanUp();
Chris@4:                 if (_hInput.IsAllocated)
Chris@4:                     _hInput.Free();
Chris@4:                 if (_hOutput.IsAllocated)
Chris@4:                     _hOutput.Free();
Chris@4: 
Chris@4:                 _isDisposed = true;
Chris@4:             }
Chris@4:         }
Chris@4: 
Chris@4: 
Chris@4:         #endregion
Chris@4: 
Chris@4:         #region Helper methods
Chris@4: 
Chris@4:         /// <summary>
Chris@4:         /// Copies a number of bytes to the internal codec buffer - ready for proccesing
Chris@4:         /// </summary>
Chris@4:         /// <param name="data">The byte array that contains the data to copy</param>
Chris@4:         /// <param name="startIndex">The index of the first byte to copy</param>
Chris@4:         /// <param name="count">The number of bytes to copy from <c>data</c></param>
Chris@4:         protected void copyInput(byte[] data, int startIndex, int count)
Chris@4:         {
Chris@4:             Array.Copy(data, startIndex, _inBuffer,0, count);
Chris@4:             _ztream.next_in = _hInput.AddrOfPinnedObject();
Chris@4:             _ztream.total_in = 0;
Chris@4:             _ztream.avail_in = (uint)count;
Chris@4: 
Chris@4:         }
Chris@4: 
Chris@4:         /// <summary>
Chris@4:         /// Resets the internal output buffers to a known state - ready for processing
Chris@4:         /// </summary>
Chris@4:         protected void resetOutput()
Chris@4:         {
Chris@4:             _ztream.total_out = 0;
Chris@4:             _ztream.avail_out = kBufferSize;
Chris@4:             _ztream.next_out = _hOutput.AddrOfPinnedObject();
Chris@4:         }
Chris@4: 
Chris@4:         /// <summary>
Chris@4:         /// Updates the running checksum property
Chris@4:         /// </summary>
Chris@4:         /// <param name="newSum">The new checksum value</param>
Chris@4:         protected void setChecksum(uint newSum)
Chris@4:         {
Chris@4:             _checksum = newSum;
Chris@4:         }
Chris@4:         #endregion
Chris@4: 
Chris@4:     }
Chris@4: }