#include "lru.h"
LRUReplacementAlg::LRUReplacementAlg(unsigned long num_frame, int page_bits):
	ReplacementAlg(num_frame, page_bits), m_count(0) 
{
	m_counts = new unsigned long [num_frame];
	for(unsigned int i = 0; i < num_frame; ++i) m_counts[i] = 0;
}

void LRUReplacementAlg::ref(const Ref &r)
{
	const PTE *pte = get_PTE_by_page(pageno(r));
	if(pte->is_valid()) m_counts[pte->get_frame()] = m_count++;
	ReplacementAlg::ref(r);
}

// Return the least-recently-used page: the one with the smallest count.
unsigned long LRUReplacementAlg::fault(const Ref &r)
{
	unsigned long ret = 0;
	unsigned long mincount = m_counts[0];
	for(unsigned long i = 1; i < get_num_frames(); ++i) {
		if(m_counts[i] < mincount) {
			ret = i;
			m_counts[i] = mincount;
		}
	}

	m_counts[ret] = m_count++;
	return ret;
}