code: public static function getByteOrder()
      {
          if (!isset(self::$byteOrder)) {
              // Check if "pack" gives the required IEEE 64bit float
              $teststr = pack('d', 1.2345);
              $number = pack('C8', 0x8D, 0x97, 0x6E, 0x12, 0x83, 0xC0, 0xF3, 0x3F);
              if ($number == $teststr) {
                  $byte_order = 0; // Little Endian
              } elseif ($number == strrev($teststr)) {
                  $byte_order = 1; // Big Endian
              } else {
                  // Give up. I'll fix this in a later version.
                  throw new WriterException('Required floating point format not supported on this platform.');
              }
              self::$byteOrder = $byte_order;
          }
  
          return self::$byteOrder;
      }
docs: Determine the byte order and store it as class data to avoid
  recalculating it for each call to new().
  
  @return int