mcs/class/ByteFX.Data/Common/BitStream.cs

   1 using System;\r
   2 using System.IO;\r
   3 \r
   4 namespace ByteFX.Data.Common\r
   5 {\r
   6         /// <summary>\r
   7         /// Summary description for BitStream.\r
   8         /// </summary>\r
   9         public class BitStream : MemoryStream\r
  10         {\r
  11                 private byte[]  _input;\r
  12                 private int             _start;\r
  13                 private int             _end;\r
  14                 private int             _bitindex;\r
  15                 private uint    _bitbuffer;\r
  16                 private int             _bits_in_buffer;\r
  17 \r
  18                 public BitStream(byte[] input, int index, int len)\r
  19                 {\r
  20                         _bitindex = 0;\r
  21                         _bitbuffer = 0;\r
  22                         _bits_in_buffer = 0;\r
  23                         _input = input;\r
  24                         _start = index;\r
  25                         _end = _start + len;\r
  26                 }\r
  27 \r
  28                 public int GetBits(int numbits)\r
  29                 {\r
  30                         return 0;\r
  31                 }\r
  32 \r
  33                 public int PeekBits(int numbits)\r
  34                 {\r
  35                         int val=0;\r
  36 \r
  37                         int index=_start;\r
  38                         while (numbits > 0)\r
  39                         {\r
  40                                 val = (val << 8) | _input[index++];\r
  41                                 numbits -= 8;\r
  42                         }\r
  43 \r
  44                         while (_bits_in_buffer < numbits)\r
  45                         {\r
  46                                 if (_start == _end)\r
  47                                         throw new Exception("Out of bits");\r
  48                                 byte b = _input[_start++];\r
  49                         }\r
  50                         return 0;\r
  51                 }\r
  52         }\r
  53 }\r