Notes

#include<stdio.h>
int n,nf;
int in[100];
int p[50];
int hit=0;
int i,j,k;
int pgfaultcnt=0;
void getData() {
printf("nEnter length of page reference sequence:");
scanf("%d",&n);
printf("nEnter the page reference sequence:");
for(i=0; i<n; i++)
scanf("%d",&in[i]);
printf("nEnter no of frames:");
scanf("%d",&nf);
}
void initialize() {
pgfaultcnt=0;
for(i=0; i<nf; i++)
p[i]=9999;
}
int isHit(int data) {
hit=0;
for(j=0; j<nf; j++) {
if(p[j]==data) {
hit=1;
break;
}
}
return hit;
}
int getHitIndex(int data) {
int hitind;
for(k=0; k<nf; k++) {
if(p[k]==data) {
hitind=k;
break;
}
}
return hitind;
}
void dispPages() {
for (k=0; k<nf; k++) {
if(p[k]!=9999)
printf(" %d",p[k]);
}
}
void dispPgFaultCnt() {
printf("nTotal no of page faults:%d",pgfaultcnt);
}
void fifo() {
initialize();
for(i=0; i<n; i++) {
printf("nFor %d :",in[i]);
if(isHit(in[i])==0) {
for(k=0; k<nf-1; k++)
p[k]=p[k+1];
p[k]=in[i];
pgfaultcnt++;
dispPages();
}
else
printf("No page fault");
}
dispPgFaultCnt();
}
void optimal() {
initialize();
int near[50];
for(i=0; i<n; i++) {
printf("nFor %d :",in[i]);
if(isHit(in[i])==0) {
for(j=0; j<nf; j++) {
int pg=p[j];
int found=0;
for(k=i; k<n; k++) {
if(pg==in[k]) {
near[j]=k;
found=1;
break;
}
else
found=0;
}
if(!found)
near[j]=9999;
}
int max=-9999;
int repindex;
for(j=0; j<nf; j++) {
if(near[j]>max) {
max=near[j];
repindex=j;
}
}
p[repindex]=in[i];
pgfaultcnt++;
dispPages();
}
else
printf("No page fault");
}
dispPgFaultCnt();
}
void lru() {
initialize();

int least[50];
for(i=0; i<n; i++)
{

printf("nFor %d :",in[i]);

if(isHit(in[i])==0)
{

for(j=0; j<nf; j++)
{
int pg=p[j];
int found=0;
for(k=i-1; k>=0; k--)
{
if(pg==in[k])
{
least[j]=k;
found=1;
break;
}
else
found=0;
}
if(!found)
least[j]=-9999;
}
int min=9999;
int repindex;
for(j=0; j<nf; j++)
{
if(least[j]<min)
{
min=least[j];
repindex=j;
}
}
p[repindex]=in[i];
pgfaultcnt++;

dispPages();
}
else
printf("No page fault!");
}
dispPgFaultCnt();
}
int main() {
int choice;
while(1) {
printf("nPage Replacement Algorithmsn1.Enter datan2.FIFOn3.Optimaln4.LRUn5.ExitnEnter your choice:");
scanf("%d",&choice);
switch(choice) {
case 1:
getData();
break;
case 2:
fifo();
break;
case 3:
optimal();
break;
case 4:
lru();
break;
default:
return 0;
break;
}
}
}