Notes

#include<stdio.h>
#include<stdlib.h>


struct process
{
int pid ;
int at ;
int bt ;
int copy_bt ;
int ct;
int wt ;
int tat ;
};

struct node
{
struct process* data ;
struct node* next ;
};

void inqueue(struct node **start , struct process *v)
{
struct node *new = (struct node *)malloc(sizeof(struct node));
new->data = v;
new->next = NULL ;
if(*start == NULL)
*start = new ;
else
{
struct node *t = *start ;
while(t->next!=NULL)
{
if(t->data == v || t->next->data == v)
return;
t = t->next;
}
t->next = new ;
}
}

int isempty(struct node **start)
{
if(*start==NULL)
return 1 ;
return 0 ;
}


struct process* dequeue(struct node **start)
{
if(!isempty(start))
{
struct node* t = *start ;
*start = t->next ;
return t->data;
}
}

void display(struct process *A , int n)
{
printf("nPtATtBTtCTtTATtWT");
for(int i = 0 ; i<n ; i++)
printf("n%dt%dt%dt%dt%dt%d" , A[i].pid, A[i].at , A[i].copy_bt, A[i].ct ,A[i].tat , A[i].wt);
}
void avgtime(struct process *A , int n)
{
int tot_wt = 0;
int tot_tat = 0;
for(int i = 0 ; i < n ; i++)
{
tot_wt = tot_wt + A[i].wt;
tot_tat = tot_tat + A[i].tat;
}
printf("nnAverage waiting time : %f" , (float)tot_wt/n );
printf("nnAverage turnaround time : %f" , (float)tot_tat/n );
}

void rr(struct node **start , struct process *A , int n , int tq)
{
int count = 0 ;
int time = A[0].at;
inqueue(start , &A[0]);
while(!isempty(start))
{
struct process *current = dequeue(start);
if(((*current).bt - tq) <= 0)
{
time = time + (*current).bt;
(*current).bt = 0 ;
(*current).ct = time ;
(*current).tat = time - (*current).at;
(*current).wt = (*current).tat - (*current).copy_bt;
count++;
}
else
{
time = time + tq;
(*current).bt = (*current).bt - tq ;
}
for(int i = 0 ; i < n ; i++)
{
if(A[i].at <= time && A[i].bt > 0 && current!=&A[i])
inqueue(start , &A[i]);
}
if((*current).bt > 0)
inqueue(start , current);
if(isempty(start))
{
for(int i = 0 ; i < n ; i++)
{
if(A[i].bt > 0)
{
time = A[i].at;
inqueue(start , &A[i]);
break;
}
}
}
}
}

int main()
{
struct node *start = NULL ;
int n = 0 , tq = 0 ;

printf("nEnter the number of processes : ");
scanf("%d" , &n);
struct process proc[n] ;
for(int i = 0 ; i<n ; i++)
{
printf("nEnter the Arrival time for process %d: " , (i+1));
proc[i].pid = i+1;
scanf("%d", &proc[i].at);
printf("nEnter the Burst time for process %d: " , (i+1));
scanf("%d",&proc[i].bt);
proc[i].copy_bt = proc[i].bt;
proc[i].ct = 0;
proc[i].wt=0;
proc[i].tat = 0;
}
printf("nEnter the time quantum : ");
scanf("%d" , &tq);


rr(&start,proc,n,tq);
printf("nnIMPLEMENTATION OF ROUND ROBIN CPU SCHEDULINGn");
display(proc,n);
avgtime(proc,n);
return 0;

}