private function _getOffsets()
{
if ($_SESSION['tmpval']['max_rows'] == self::ALL_ROWS) {
$pos_next = 0;
$pos_prev = 0;
} else {
$pos_next = $_SESSION['tmpval']['pos'] + $_SESSION['tmpval']['max_rows'];
$pos_prev = $_SESSION['tmpval']['pos'] - $_SESSION['tmpval']['max_rows'];
if ($pos_prev < 0) {
$pos_prev = 0;
}
}
return array($pos_next, $pos_prev);
}