//#include "stdafx.h"
#include<stdio.h>
#include<stdlib.h>
#include<stdbool.h>
#define VM_PAGE 7      /*Number of virtual pages*/
#define PM_PAGE 4         /* Number of memory blocks allocated to the job */
#define TOTAL_INSERT 18 /*Number of virtual page replacements*/
typedef struct
{
	int vmn;
	int pmn;
	int exist;
	int time;
}vpage_item;
vpage_item page_table[VM_PAGE];

vpage_item* ppage_bitmap[PM_PAGE];

int vpage_arr[TOTAL_INSERT] = { 1,2,3,4,2,6,2,1,2,3,7,6,3,2,1,2,3,6 }; // The access order virtual pages


void init_data() //initialize data
{
	for (int i = 0; i<VM_PAGE; i++)
	{
		page_table[i].vmn = i + 1;  
		page_table[i].pmn = -1;    
		page_table[i].exist = 0;
		page_table[i].time = -1;

	}
	for (int i = 0; i<PM_PAGE; i++) /*initialize the physical page map*/
	{
		ppage_bitmap[i] = NULL;
	}
}

void FIFO()/*FIFO page replacement algorithem*/
{
	int k = 0;
	int i;
	int sum = 0;
	int missing_page_count = 0;
	int current_time = 0;
	bool isleft = true;  /* Whether there are remaining physical blocks */
	while (sum < TOTAL_INSERT)
	{
		if (page_table[vpage_arr[sum] - 1].exist == 0)
		{
			missing_page_count++;
			if (k < 4)
			{
				if (ppage_bitmap[k] == NULL) /*find a free block*/
				{
					ppage_bitmap[k] = &page_table[vpage_arr[sum] - 1];
					ppage_bitmap[k]->exist = 1;
					ppage_bitmap[k]->pmn = k;
					ppage_bitmap[k]->time = current_time;
					k++;
				}
			}
			else
			{
				int temp = ppage_bitmap[0]->time;	
				int j = 0;                    
				for (i = 0; i < PM_PAGE; i++)
				{
					if (ppage_bitmap[i]->time < temp)
					{
						temp = ppage_bitmap[i]->time;
						j = i;
					}
				}
				ppage_bitmap[j]->exist = 0;
				ppage_bitmap[j] = &page_table[vpage_arr[sum] - 1]; /*update page table */
				ppage_bitmap[j]->exist = 1;
				ppage_bitmap[j]->pmn = j;
				ppage_bitmap[j]->time = current_time;
			}
		}
		current_time++;
		sum++;
	}
	printf("The number of page faults of FIFO is:%d\t Page fault rate:%f\t The number of replacement:%d\tReplacement rate:%f\n", missing_page_count, missing_page_count / (float)TOTAL_INSERT, missing_page_count - 4, (missing_page_count - 4) / (float)TOTAL_INSERT);
    
}
void LRU()
{
}
void OPT()
{
}

int main()
{
	int a;	
	do
	{
		printf("Please choose page replacement algorithm：1.FIFO\t2.LRU\t3.OPT\t0. quit\n");
		scanf_s("%d", &a);
		switch (a)
		{
		case 1:
			init_data();
			FIFO();
			break;
		case 2:
			init_data();
			LRU();
			break;
		case 3:
			init_data();
			OPT();
			break;
		}
	} while (a != 0);
	return 0;
}