/* Lab7 - To implement FIFO page replacement algo
 * Pravin Paratey (pravin[AT]iitb.ac.in)
 */
 
#include <stdio.h>
 
 
int FrameBuffer[100][2];
 
int main()
{
	FILE *fp;
	int numFrames;
	int pageHits=0;
	int count=0;
	int pageNum;
	int purgeMem;
	int i;
	int eof;
	int leastUsed=0;
	int leastIndex=0;
 
	fp = fopen("lru.in","r");
	fscanf(fp, "%i", &numFrames);
 
	while(1)
	{
		eof = fscanf(fp, "%i", &pageNum);
		if (eof == -1)
			break;
 
		printf("[%i] Requested\n",pageNum);
		purgeMem=1;
		for(i=0;i<numFrames;i++)
			if (FrameBuffer[i][0] == pageNum)
			{
				pageHits++;
				FrameBuffer[i][1]++;
				purgeMem=0;
				printf("[%i] Found\n",pageNum);
			}
		if (purgeMem)
		{
			leastUsed=100;
			leastIndex=0;
			for(i=0;i<numFrames;i++)
			{
				if(FrameBuffer[i][1] < leastUsed)
				{
					leastUsed=FrameBuffer[i][1];
					leastIndex=i;
				}
			}
			printf("[%i] Not Found ... added -%i- purged\n",pageNum,FrameBuffer[leastIndex][0]);
			FrameBuffer[leastIndex][0] = pageNum;
			FrameBuffer[leastIndex][1] = 0;
		}
		count++;
 
	}
 
	printf("Total pages requested=%i\nPage Hits=%i\nHit Rate=%f",
			count, pageHits, (float)pageHits/(float)count);
	fclose(fp);
	return 0;
}