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      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 
     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 
     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 
     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 
     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 
     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