u-tools/apps/zlib/contrib/dotzlib/DotZLib/CircularBuffer.cs

   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 }