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
  8using System;
  9using System.Diagnostics;
 10using System.Runtime.InteropServices;
 11
 12namespace DotZLib
 13{
 14
 15    /// <summary>
 16    /// Implements a data decompressor, using the inflate algorithm in the ZLib dll
 17    /// </summary>
 18    public class Inflater : CodecBase
 19	{
 20        #region Dll imports
 21        [DllImport("ZLIB1.dll", CallingConvention=CallingConvention.Cdecl, CharSet=CharSet.Ansi)]
 22        private static extern int inflateInit_(ref ZStream sz, string vs, int size);
 23
 24        [DllImport("ZLIB1.dll", CallingConvention=CallingConvention.Cdecl)]
 25        private static extern int inflate(ref ZStream sz, int flush);
 26
 27        [DllImport("ZLIB1.dll", CallingConvention=CallingConvention.Cdecl)]
 28        private static extern int inflateReset(ref ZStream sz);
 29
 30        [DllImport("ZLIB1.dll", CallingConvention=CallingConvention.Cdecl)]
 31        private static extern int inflateEnd(ref ZStream sz);
 32        #endregion
 33
 34        /// <summary>
 35        /// Constructs an new instance of the <c>Inflater</c>
 36        /// </summary>
 37        public Inflater() : base()
 38		{
 39            int retval = inflateInit_(ref _ztream, Info.Version, Marshal.SizeOf(_ztream));
 40            if (retval != 0)
 41                throw new ZLibException(retval, "Could not initialize inflater");
 42
 43            resetOutput();
 44        }
 45
 46
 47        /// <summary>
 48        /// Adds more data to the codec to be processed.
 49        /// </summary>
 50        /// <param name="data">Byte array containing the data to be added to the codec</param>
 51        /// <param name="offset">The index of the first byte to add from <c>data</c></param>
 52        /// <param name="count">The number of bytes to add</param>
 53        /// <remarks>Adding data may, or may not, raise the <c>DataAvailable</c> event</remarks>
 54        public override void Add(byte[] data, int offset, int count)
 55        {
 56            if (data == null) throw new ArgumentNullException();
 57            if (offset < 0 || count < 0) throw new ArgumentOutOfRangeException();
 58            if ((offset+count) > data.Length) throw new ArgumentException();
 59
 60            int total = count;
 61            int inputIndex = offset;
 62            int err = 0;
 63
 64            while (err >= 0 && inputIndex < total)
 65            {
 66                copyInput(data, inputIndex, Math.Min(total - inputIndex, kBufferSize));
 67                err = inflate(ref _ztream, (int)FlushTypes.None);
 68                if (err == 0)
 69                    while (_ztream.avail_out == 0)
 70                    {
 71                        OnDataAvailable();
 72                        err = inflate(ref _ztream, (int)FlushTypes.None);
 73                    }
 74
 75                inputIndex += (int)_ztream.total_in;
 76            }
 77            setChecksum( _ztream.adler );
 78        }
 79
 80
 81        /// <summary>
 82        /// Finishes up any pending data that needs to be processed and handled.
 83        /// </summary>
 84        public override void Finish()
 85        {
 86            int err;
 87            do
 88            {
 89                err = inflate(ref _ztream, (int)FlushTypes.Finish);
 90                OnDataAvailable();
 91            }
 92            while (err == 0);
 93            setChecksum( _ztream.adler );
 94            inflateReset(ref _ztream);
 95            resetOutput();
 96        }
 97
 98        /// <summary>
 99        /// Closes the internal zlib inflate stream
100        /// </summary>
101        protected override void CleanUp() { inflateEnd(ref _ztream); }
102
103
104	}
105}