Getting of the page item in the list, Bitrix

<?php
 /**
  * Getting of the page item in the list
  *
  * @access public
  * @param array $arParams params element (only `int` type)
  * @param array $arFilter filter elements
  * @param array $arSort sort elements
  * @return int
  * @api
  */
 function GetNumPageElement (array $arParams, array $arFilter, array $arOrder = array('SORT' => 'ASC'))
 {
         //LQ_FI::CleanArrayInt($arParams);

         // -> check
     if ($arParams['ID'] < 1 or $arParams['nPageSize'] < 1)
     {
         return 1;
     }

     // -> complex?
     $complex = isset($arOrder['SORT']) && count($arOrder) > 1;

     // -> ib interface
     $arFilter['ACTIVE'] = 'Y';

         // -> section
     if ($arParams['SECTION_ID'] > 0)
     {
         $arFilter['SECTION_ID'] = $arParams['SECTION_ID'];
     }

     // -> limit
     if ($complex === FALSE)
     {
         foreach ($arOrder as $key => $by)
         {
             if (isset($arParams[$key]))
             {
                 $prefix = (mb_stripos($by, 'asc') !== FALSE) ? '<=' : '>=';

                                 // -> add filter of limit
                                 $arFilter[$prefix.$key] = $arParams[$key];
             }
         }
     }

     unset($arFilter['ID']);

     // -> get
     $obj = CIBlockElement::GetList($arOrder, $arFilter, FALSE, FALSE, array('ID'));

     // -> rows count
     $rowsCount = $obj->SelectedRowsCount();

     // -> logic complex
     if ($complex === TRUE)
     {
         $rowsCount = 0;

         // -> rows
         while ($arItem = $obj->Fetch())
         {
             ++$rowsCount;

             // -> point break
             if ($arItem['ID'] == $arParams['ID']) break;
         }
     }

     // -> calculate
     if ($rowsCount <= $arParams['nPageSize'])
     {
         return 1;
     }

     return ceil($rowsCount/$arParams['nPageSize']);
 }
?>