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}
106