PageRepAlgo.c

#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("\n\t17BCE0544\n\tPage Replacement Algorithms\n1.Enter data\n2.FIFO\n3.Optimal\n4.LRU\n5.Exit\nEnter 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;
        }
    }
}