{if $smarty.get.id_category|intval}
    {assign var='request' value=$link->getPaginationLink('category', $category, false, true)}
{elseif $smarty.get.id_manufacturer|intval}
    {assign var='request' value=$link->getPaginationLink('manufacturer', $manufacturer, false, true)}
{elseif $smarty.get.id_supplier|intval}
    {assign var='request' value=$link->getPaginationLink('supplier', $supplier, false, true)}
{else}
    {assign var='request' value=$link->getPaginationLink(false, false, false, true)}
{/if}
<form id="productsSortForm" action="{$request}">
    <p class="select">
        <select id="selectPrductSort" onchange="document.location.href = $(this).val();">
            <option value="{$link->addSortDetails($request, 'position', $orderwayposition)|escape:'htmlall':'UTF-8'}" {if $orderby eq 'position'}selected="selected"{/if}>{l s='--'}</option>
            <option value="{$link->addSortDetails($request, 'price', 'asc')|escape:'htmlall':'UTF-8'}" {if $orderby eq 'price'    AND $orderway eq 'ASC' }selected="selected"{/if}>{l s='price: lowest first'}</option>
            <option value="{$link->addSortDetails($request, 'price', 'desc')|escape:'htmlall':'UTF-8'}" {if $orderby eq 'price'    AND $orderway eq 'DESC'}selected="selected"{/if}>{l s='price: highest first'}</option>
            <option value="{$link->addSortDetails($request, 'name', 'asc')|escape:'htmlall':'UTF-8'}" {if $orderby eq 'name'     AND $orderway eq 'ASC' }selected="selected"{/if}>{l s='name: A to Z'}</option>
            <option value="{$link->addSortDetails($request, 'name', 'desc')|escape:'htmlall':'UTF-8'}" {if $orderby eq 'name'     AND $orderway eq 'DESC'}selected="selected"{/if}>{l s='name: Z to A'}</option>
            <option value="{$link->addSortDetails($request, 'quantity', 'desc')|escape:'htmlall':'UTF-8'}" {if $orderby eq 'quantity' AND $orderway eq 'DESC' }selected="selected"{/if}>{l s='in-stock first'}</option>
        </select>
        <label for="selectPrductSort">{l s='sort by'}</label>
    </p>
</form>

function performSearch(Smarty $smarty, $page = 1, $perPage = 10, $orderBy = 'newest', $orderWay = 'DESC')
....
if($orderBy == 'price') $orderBy = 'orderprice';

if($orderBy == 'quantity') $orderBy = 'quantity';

<li><a href="#price_desc">{l s='Price Highest' mod='filtersearch'}</a></li>

<li><a href="#quantity">{l s='+' mod='filtersearch'}</a></li>

<div id="price_desc"></div>

<div id="quantity"></div>