是否可以使快速排序函数排序数组降序?

我得到了下面的php函数,想把它改成降序排序,有人能帮我吗:

function quickSort(&$numbers, $array_size,$level)
{
   q_sort($numbers, 0, $array_size - 1,$level);
}


function q_sort(&$numbers, $left, $right,$level)
{
   $l_hold = $left;
   $r_hold = $right;
   $pivot = $numbers[$left];


   while ($left < $right)
   {
      if ($level == 'RegID')
      {
         while (($numbers[$right]->RegID >= $pivot->RegID) && ($left < $right))
            $right--;
      }


      if ($left != $right)
      {
         $numbers[$left] = $numbers[$right];
         $left++;
      }

      if($level == 'RegID')
      {
         while (($numbers[$left]->RegID >= $pivot->RegID) && ($left < $right))
            $left++;
      }



      if ($left != $right)
      {
         $numbers[$right] = $numbers[$left];
         $right--;
      }
   }

   $numbers[$left] = $pivot;
   $pivot = $left;
   $left = $l_hold;
   $right = $r_hold;

   if ($left < $pivot)
      q_sort($numbers, $left, $pivot-1,$level);
   if ($right > $pivot)
      q_sort($numbers, $pivot+1, $right,$level);

}