if (Tools::getValue('orderby') === 'reduction')
{
    foreach ($this->cat_products as &$row)
        $row['price_tmp'] = $row['price_without_reduction'] - $row['price'];
    
    if (Tools::getValue('orderway') === 'asc')
        uasort($this->cat_products, 'cmpPriceAsc');
    else
        uasort($this->cat_products, 'cmpPriceDesc');
}

$this->pagination($this->nbProducts);