Round Robin Scheduling Algorithm Implementation Using C

Coding:

#include<stdio.h>

#define FINISHED 0

#define WAITING 1

#define RUNNING 2

struct pro

{

 char ID[6];

 int burst_time;

 int wait_time;

 int turn_time;

 int state;

}process[10];

int no;

 void main()

 {

 int i,j,sum,time=0,time_slice=1,curr_proc,prev_time=0,sturn=0;

 int fin=0;

 printf("\nEnter the no of process:");

 scanf("%d",&no);

 for(i=1;i<=no;i++)

 {

   printf("\nEnter process ID:");

   scanf("%s",process[i].ID);

   printf("\nEnter cpu burst time:");

   scanf("%d",&process[i].burst_time);

   process[i].wait_time=0;

   process[i].turn_time=process[i].burst_time;

   process[i].state=WAITING;

   }

   curr_proc=1;

   process[curr_proc].state=RUNNING;

   while(1)

   {

   process[curr_proc].burst_time--;

   time++;

   for(j=1;j<=no;j++)

   {

     if(process[j].state==WAITING)

     {

       process[j].wait_time++;

       process[j].turn_time++;

       }

   }

   if(time_slice==5||process[curr_proc].burst_time==0)

   {

   if (process[curr_proc].burst_time==0)

   {

   process[curr_proc].state=FINISHED;

   fin++;

   }

   else

   process[curr_proc ].state=WAITING;

   printf("\n%s-%d to %d",process[curr_proc].ID,prev_time,time);

   if(fin==no)

   break;

   curr_proc=curr_proc%no+1;

   while(process[curr_proc].state==FINISHED)

   {

   curr_proc=curr_proc%no+1;

   }

   process[curr_proc].state=RUNNING;

   prev_time=time;

   time_slice=0;

   }

   time_slice++;

   }

   printf("\n\n Process Waitingtime Turnaround time\n\n");

   sum=0;

   for(i=1;i<=no;i++)

   {

   sum+=process[i].wait_time;

   sturn+=process[i].turn_time;

   printf("\n%s\t%d\t\t%d",process[i].ID,process[i].wait_time,process[i].turn_time);

   }

   printf("\n\nAverage waiting time:%.2f\n",(float)sum/(float)no);

   printf("\nAverage turn around time:%.2f\n",(float)sturn/(float)no);

 }

Output:

Enter process ID:P1

Enter cpu burst time:9

Enter process ID:P2

Enter cpu burst time:12

Enter process ID:P3

Enter cpu burst time:10

P1-0 to 5

P2-5 to 10

P3-10 to 15

P1-15 to 19

P2-19 to 24

P3-24 to 29

P2-29 to 31

 Process Waitingtime Turnaround time

P1      10              19

P2      19              31

P3      19              29

Average waiting time:16.00

Average turn around time:26.33