function dl_file_resume($filepath, $filename, $throttle = 0, $callback = '')

{     

  //Get the content type

  $content_type = my_get_mime_type($filename);

  

  //Begin writing headers

  header('Cache-Control:');

  header('Cache-Control: public');

  

  //Use the switch-generated Content-Type

  header('Content-Type: ' . $content_type);

   

  if (stristr($_SERVER['HTTP_USER_AGENT'], 'MSIE'))

  {

    //workaround for IE filename bug with multiple periods / multiple dots in filename

    //that adds square brackets to filename - eg. setup.abc.exe becomes setup[1].abc.exe

    $iefilename = preg_replace('/\./', '%2e', $filename, substr_count($filename, '.') - 1);

    header('Content-Disposition: attachment; filename="' . $iefilename . '"');

  }

  else

    header('Content-Disposition: attachment; filename="' . $filename . '"');



  header('Accept-Ranges: bytes');

  

  $filesize = filesize($filepath);

   

  //check if http_range is sent by browser (or download manager)

  if (isset($_SERVER['HTTP_RANGE']))

  {

    list($a, $range) = explode('=', $_SERVER['HTTP_RANGE']);     

    //if yes, download missing part     

    str_replace($range, '-', $range);

    $size2 = $filesize - 1;

    $new_length = $size2 - $range;

     

    header('HTTP/1.1 206 Partial Content');

    header("Content-Length: $new_length");

    header("Content-Range: bytes $range$size2/$filesize");

  }

  else

  {

    $size2 = $filesize - 1;

    header("Content-Range: bytes 0-$size2/$filesize");

    header('Content-Length: ' . $filesize);

  }

   

  //open the file

  $fp = fopen($filepath, 'rb');

   

  //seek to start of missing part

  @fseek($fp, $range);

   

  //start buffered download

  while (!feof($fp))

  {

    //reset time limit for big files

    set_time_limit(0);

    

    if ($throttle != 0)

    {

      echo fread($fp, 1024 * $throttle);

      sleep(1); 

    }

    else

      echo fread($fp, 1024 * 8);

    

    if ($callback())

      break;

    

    flush();

    @ob_flush();

  }

   

  fclose($fp);

}