BlockBuffer *MRUBlockManager::MakeBlockResident(ArrayIndex p_BlockNumber, ArrayIndex &p_OldBufferNumber)
{
	ArrayIndex i;
	ArrayIndex EarliestStamp;
	time_t TimeStamp;

	if (m_BlockNumber[p_OldBufferNumber] == p_BlockNumber)
		{
		m_TimeStamp[p_OldBufferNumber] = time(NULL);
		return m_BlockBuffer[p_OldBufferNumber];
		}

	for (i = 0; i < m_BlockNumber.GetSize(); i ++)
		{
		if (m_BlockNumber[i] == p_BlockNumber)
			{
			m_TimeStamp[i] = time(NULL);
			return m_BlockBuffer[i];
			}
		}

	TimeStamp = WayInTheFuture;
	for (i = 0; i < m_TimeStamp.GetSize(); i ++)
		{
		if (m_TimeStamp[i] < TimeStamp) // find the earliest timestamp
			{
			TimeStamp = m_TimeStamp[i];
			EarliestStamp = i;
			}
		}

	if (m_BufferModified[EarliestStamp]) /* it needs to be written out */
		Write(EarliestStamp);

	// set block number of new occupant
	m_BlockNumber[EarliestStamp] = p_BlockNumber;

	m_BufferModified[EarliestStamp] = FALSE; // not modified yet
	m_TimeStamp[EarliestStamp] = time(NULL);
	Read(EarliestStamp);

	p_OldBufferNumber = EarliestStamp;

	return m_BlockBuffer[EarliestStamp];
}