gzencode and stream http archive

function gzencode_stream($input, $level = -1, $mode = FORCE_GZIP) {
  $mode = in_array($mode, array(FORCE_GZIP, FORCE_DEFLATE, FORCE_DEFLATE), TRUE) ? $mode : FORCE_GZIP;
  $level = ($level = (int)$level) < 0 || $level > 9 ? -1 : $level;
  if (function_exists('gzdeflate')) {
    $mode = ($mode == FORCE_GZIP) ? FORCE_DEFLATE : $mode;
  } elseif (function_exists('gzencode') && $mode == FORCE_GZIP) {
    return gzencode($input, $level);
  } elseif (function_exists('gzcompress') && $mode == FORCE_DEFLATE) {
    return gzcompress($input, $level);
  }
  $flags = ($mode == FORCE_DEFLATE) ? FORCE_DEFLATE : 0