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