Write the simulation program for demand paging and show the page scheduling and total number of page faults according to LRU page replacement algorithm. Assume the memory of ‘n’ frames

#include<stdio.h>

int RefString[20],PT[10],nof,nor;

void Accept()
{
int i;
printf("Enter Reference String: \n");
for(i=0;i<nor;i++)
{
printf("[%d]=",i+1);
scanf("%d",&RefString[i]);
}
}

int Search(int s)
{
int i;
for(i=0;i<nof; i++)
if(PT[i]==s)
return(i);
return(-1);
}

int GetLFU(int e, int s)
{
int i,j,cnt1=0,cnt2,posi;
i=s;
do
{
cnt2=0;
for(j=e-1;j>=0;j--)
{
if(PT[i]==RefString[j])
{
cnt2++;
}
}
if(cnt2<cnt1)
{
cnt1=cnt2;
posi = i;
}
i=(i+1)%nof;
}while(i!=s);
return(posi);
}

void LFU()
{
int i,j,k,Faults=1;
clrscr();
for(k=0,i=0; k<nof && i<nor; i++)
{
gotoxy(3*i+1,2);
printf("%2d",RefString[i]);
if(Search(RefString[i])==-1)
{
PT[k]=RefString[i];
for(j=0;j<nof;j++)
{
gotoxy(3*i+1,j+3);
if(PT[j])
printf("%2d",PT[j]);
}
Faults++;
k++;
}
}
k=0;
while(i<nor)
{
gotoxy(3*i+1,2);
printf("%2d",RefString[i]);
if(Search(RefString[i])==-1)
{
k = GetLFU(i,k);
PT[k]=RefString[i];
k=(k+1)%nof;
for(j=0;j<nof;j++)
{
gotoxy(3*i+1,j+3);
if(PT[j])
printf("%2d",PT[j]);
}
Faults++;
}
i++;
}
gotoxy(10,24);
printf("Total Page Faults: %d",Faults);
}

main()
{
clrscr();
printf("Enter Length of reference string: ");
scanf("%d",&nor);
printf("Enter No.of Frames: ");
scanf("%d",&nof);
Accept();
LFU();
getch();
}