Notes

#include<stdio.h>
struct process
{
char name;
int at,bt,wt,tt,rt;
int completed;
float ntt;
}p[10];
int n;
int q[100]; //queue
int front=-1,rear=-1;
void enqueue(int i)
{
if(rear==100)
{
printf("overflow");
return 0;
}rear++;
q[rear]=i;
if(front==-1)
front=0;

}

int dequeue()
{
if(front==-1)
{
printf("underflow");
return 0;
} int temp=q[front];
if(front==rear)
front=rear=-1;
else
front++;
return temp;
}
int isInQueue(int i)
{int k;
for(k=front;k<=rear;k++)
{
if(q[k]==i)
return 1;
}
return 0;

}void sortByArrival()
{
struct process temp;
int i,j;
for(i=0;i<n-1;i++)
for(j=i+1;j<n;j++)
{
if(p[i].at>p[j].at)
{
temp=p[i];
p[i]=p[j];
p[j]=temp;
}
}
}

void main()
{
int i,j,time=0,sum_bt=0,tq;
char c;
float avgwt=0;
printf("Enter no of processes:");
scanf("%d",&n);
for(i=0,c='A';i<n;i++,c++)
{
p[i].name=c;
printf("nEnter the arrival time and burst time of process %c: ",p[i].name);
scanf("%d%d",&p[i].at,&p[i].bt);
p[i].rt=p[i].bt;
p[i].completed=0;
sum_bt+=p[i].bt;

}

printf("nEnter the time quantum:");
scanf("%d",&tq);

sortByArrival();
enqueue(0); // enqueue the first process
printf("Process execution order: ");
for(time=p[0].at;time<sum_bt;) // run until the total burst time reached
{ i=dequeue();

if(p[i].rt<=tq)
{ // for processes having remaining time with less than or equal time quantum

time+=p[i].rt;
p[i].rt=0;
p[i].completed=1;
printf(" %c ",p[i].name);
p[i].wt=time-p[i].at-p[i].bt;
p[i].tt=time-p[i].at;
p[i].ntt=((float)p[i].tt/p[i].bt);
for(j=0;j<n;j++) // enqueue the processes which have come while scheduling
{
if(p[j].at<=time && p[j].completed!=1&& isInQueue(j)!=1)
{
enqueue(j);

}
}
}
else // more than time quantum
{
time+=tq;
p[i].rt-=tq;
printf(" %c ",p[i].name);
for(j=0;j<n;j++) //enqueue the processes which have come scheduling first
{
if(p[j].at<=time && p[j].completed!=1&&i!=j&& isInQueue(j)!=1)
{
enqueue(j);

}
}
enqueue(i); // then enqueue the uncompleted process

}



}

printf("nNametArrival TimetBurst TimetWaiting TimetTurnAround Timet Normalized TT");
for(i=0;i<n;i++)
{avgwt+=p[i].wt;
printf("n%ctt%dtt%dtt%dtt%dtt%f",p[i].name,p[i].at,p[i].bt,p[i].wt,p[i].tt,p[i].ntt);
}
printf("nAverage waiting time:%fn",avgwt/n);
}