CCITTFaxFileScan.cs

using System;
using System.Collections.Generic;
using System.IO;
using System.Linq;
using System.Text;
using System.Threading.Tasks;

namespace CCITTFaxFileScan
{
  class Program
  {
    static void Main(string[] args)
    {
      FileStream itwFile = File.OpenRead(args[0]);
      Console.WriteLine("Scanning for EOFB with fill order msb-first");
      ScanForEOFB(itwFile, 1);
      Console.WriteLine("Scanning for EOFB with fill order lsb-first");
      ScanForEOFB(itwFile, 2);
      Console.WriteLine("Scanning for EOL with fill order msb-first");
      ScanForEOL(itwFile, 1);
      Console.WriteLine("Scanning for EOL with fill order lsb-first");
      ScanForEOL(itwFile, 2);
      Console.ReadLine();
    }

    private static void ScanForEOFB(FileStream itwFile, int fillOrder)
    {
      const int EOFB = 0x1001; //000000000001000000000001
      itwFile.Seek(0, SeekOrigin.Begin);
      int last24Bits = 0;
      int bi;
      while ((bi = itwFile.ReadByte()) != -1)
      {
        byte b = (byte)bi;
        for (int bit = 0; bit < 8; bit++)
        {
          last24Bits <<= 1;
          last24Bits &= 0x00FFFFFF;
          if (fillOrder == 1)
            last24Bits |= (b >> (7-bit)) & 1;
          else
            last24Bits |= (b >> bit) & 1;
          if (last24Bits == EOFB)
          {
            Console.WriteLine("EOFB at {0:X8}.{1}", itwFile.Position, bit);
          }
        }
      }
    }

    private static void ScanForEOL(FileStream itwFile, int fillOrder)
    {
      const int EOL = 0x1; //0000 0000-0001
      itwFile.Seek(0, SeekOrigin.Begin);
      int last12Bits = 0;
      int bi;
      while ((bi = itwFile.ReadByte()) != -1)
      {
        byte b = (byte)bi;
        for (int bit = 0; bit < 8; bit++)
        {
          last12Bits <<= 1;
          last12Bits &= 0x00000FFF;
          if (fillOrder == 1)
            last12Bits |= (b >> (7-bit)) & 1;
          else
            last12Bits |= (b >> bit) & 1;
          if (last12Bits == EOL)
          {
            Console.WriteLine("EOL at {0:X8}.{1}", itwFile.Position, bit);
          }
        }
      }
    }
  }
}