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 
8 using System;
9 using System.Diagnostics;
10 
11 namespace DotZLib
12 {
13 
14 	/// <summary>
15 	/// This class implements a circular buffer
16 	/// </summary>
17 	internal class CircularBuffer
18 	{
19         #region Private data
20         private int _capacity;
21         private int _head;
22         private int _tail;
23         private int _size;
24         private byte[] _buffer;
25         #endregion
26 
CircularBuffer(int capacity)27         public CircularBuffer(int capacity)
28         {
29             Debug.Assert( capacity > 0 );
30             _buffer = new byte[capacity];
31             _capacity = capacity;
32             _head = 0;
33             _tail = 0;
34             _size = 0;
35         }
36 
37         public int Size { get { return _size; } }
38 
Put(byte[] source, int offset, int count)39         public int Put(byte[] source, int offset, int count)
40         {
41             Debug.Assert( count > 0 );
42             int trueCount = Math.Min(count, _capacity - Size);
43             for (int i = 0; i < trueCount; ++i)
44                 _buffer[(_tail+i) % _capacity] = source[offset+i];
45             _tail += trueCount;
46             _tail %= _capacity;
47             _size += trueCount;
48             return trueCount;
49         }
50 
Put(byte b)51         public bool Put(byte b)
52         {
53             if (Size == _capacity) // no room
54                 return false;
55             _buffer[_tail++] = b;
56             _tail %= _capacity;
57             ++_size;
58             return true;
59         }
60 
Get(byte[] destination, int offset, int count)61         public int Get(byte[] destination, int offset, int count)
62         {
63             int trueCount = Math.Min(count,Size);
64             for (int i = 0; i < trueCount; ++i)
65                 destination[offset + i] = _buffer[(_head+i) % _capacity];
66             _head += trueCount;
67             _head %= _capacity;
68             _size -= trueCount;
69             return trueCount;
70         }
71 
Get()72         public int Get()
73         {
74             if (Size == 0)
75                 return -1;
76 
77             int result = (int)_buffer[_head++ % _capacity];
78             --_size;
79             return result;
80         }
81 
82     }
83 }
84