Paginator::calculateQueryLimits

static function calculateQueryLimits($numberOfRecords, $pageNumber, $numberOfRecordsPerPage, $backward)
{
	$pageNumber = intval($pageNumber);
	$numberOfRecords = intval($numberOfRecords);

	$numberOfRecordsPerPage = intval($numberOfRecordsPerPage);
	if ($numberOfRecordsPerPage <= 0)
		$numberOfRecordsPerPage = 10;

	$pageCount = floor($numberOfRecords / $numberOfRecordsPerPage);
	if ($backward)
	{
		$makeweight = ($numberOfRecords % $numberOfRecordsPerPage);
		if ($pageCount == 0 && $makeweight > 0)
			$pageCount = 1;

		if ($pageNumber < 1)
			$pageNumber = 1;
		if ($pageNumber > $pageCount)
			$pageNumber = $pageCount;

		$firstRecordToShow = 0;
		if ($pageNumber != $pageCount)
			$firstRecordToShow += $makeweight;

		$firstRecordToShow += ($pageCount - $pageNumber) * $numberOfRecordsPerPage;
		$lastRecordToShow = $makeweight + ($pageCount - $pageNumber + 1) * $numberOfRecordsPerPage;
	}
	else
	{
		if ($numberOfRecordsPerPage && ($numberOfRecords % $numberOfRecordsPerPage > 0))
			$pageCount++;

		if ($pageNumber < 1)
			$pageNumber = 1;
		if ($pageNumber > $pageCount)
			$pageNumber = $pageCount;

		$firstRecordToShow = $numberOfRecordsPerPage * ($pageNumber - 1);
		$lastRecordToShow = $numberOfRecordsPerPage * $pageNumber;
	}

	return array($firstRecordToShow, $lastRecordToShow - $firstRecordToShow);
}