private static byte[] _file;
        public static int FindPattern(byte[] btPattern, string strMask)
        {
            try
            {
                if (strMask.Length != btPattern.Length)
                    return -1;
                for (int x = 0; x < _file.Length; x++)
                {
                    if (MaskCheck(x, btPattern, strMask))
                    {
                        return x;
                    }
                }
                return -1;
            }
            catch (Exception ex)
            {
                return -1;
            }
        }

        private static bool MaskCheck(int nOffset, byte[] btPattern, string strMask)
        {
            for (int x = 0; x < btPattern.Length; x++)
            {
                if (strMask[x] == '?')
                    continue;

                if ((strMask[x] == 'x') && (btPattern[x] != _file[nOffset + x]))
                    return false;
            }
            return true;
        }