cpu scheduling program

CPU SCHEDULING

#include<iostream.h>

#include<conio.h>

class schedule

{

  public:

    int bt,wt,at,tbt,twt,tat,p,t;

    float awt,abt,aat;

};

schedule ob,obp[100];

int i,j,k,n,t,p[50],pa[100],bt[100];

void get()

{

  ob.twt=0,ob.tat=0,ob.tbt=0;

  cout<<"\nEnter the number of process: ";

  cin>>n;

  for(i=1;i<=n;i++)

  {

   cout<<"\nEnter the Burst Time for P"<<i<<" : ";

   cin>>obp[i].bt;

   bt[i]=obp[i].bt;

   ob.tbt=ob.tbt+obp[i].bt;

   obp[i].t=0;

   p[i]=i;

  }

}

void disp()

{

  cout<<"\n\n";

  for(i=1;i<=n;i++)

  {

   cout<<"\nBurst time for P"<<i<<"       : "<<obp[i].bt<<endl;

   cout<<"\nWaiting time for P"<<i<<"     : "<<obp[i].wt<<endl;

   cout<<"\nTurnAround time for P"<<i<<"  : "<<obp[i].at<<endl;

  }

  cout<<"\nTotal Burst time  : "<<ob.tbt<<endl;

  cout<<"\nTotal Waiting time: "<<ob.twt<<endl;

  cout<<"\nTotal Around time : "<<ob.tat<<endl;

  cout<<"\nAverage Burst time     : "<<ob.abt<<endl;

  cout<<"\nAverage Waiting time   : "<<ob.awt<<endl;

  cout<<"\nAverage TurnAround time: "<<ob.aat<<endl;

}

void fcfs()

{

 clrscr();

 get();

 cout<<"\n\nFCFS Process Array: \n\n";

 for(i=1;i<=n;i++)

  cout<<"P"<<i<<"\t";

 i=1;

 obp[i].wt=0;

 obp[i].at=obp[1].bt;

 for(i=2;i<=n;i++)

 {

  obp[i].wt=obp[i-1].wt+obp[i-1].bt;

  obp[i].at=obp[i].wt+obp[i].bt;

 }

 for(i=1;i<=n;i++)

 {

  ob.twt=ob.twt+obp[i].wt;

  ob.tat=ob.tat+obp[i].at;

 }

 ob.awt=(float)ob.twt/n;

 ob.abt=(float)ob.tbt/n;

 ob.aat=(float)ob.tat/n;

 disp();

}

void sjf()

{

 clrscr();

 get();

 for(i=1;i<=n;i++)

 for(j=1;j<=n;j++)

 if(bt[i]<bt[j])

 {

  t=bt[i];

  bt[i]=bt[j];

  bt[j]=t;

 }

 for(i=1;i<=n;i++)

 for(j=1;j<=n;j++)

 if(bt[i]==obp[j].bt)

 {

  p[i]=j;

 }

 cout<<"\nShortest Job First Process Array: \n\n";

 for(i=1;i<=n;i++)

  cout<<"P"<<p[i]<<"\t";

 cout<<"\n\n\n";

 i=1;

 obp[p[i]].wt=0;

 obp[p[i]].at=obp[p[i]].bt;

 for(i=2;i<=n;i++)

 {

  obp[p[i]].wt=obp[p[i-1]].wt+obp[p[i-1]].bt;

  obp[p[i]].at=obp[p[i]].wt+obp[p[i]].bt;

 }

 for(i=1;i<=n;i++)

 {

  ob.twt=ob.twt+obp[i].wt;

  ob.tat=ob.tat+obp[i].at;

 }

 ob.awt=(float)ob.twt/n;

 ob.abt=(float)ob.tbt/n;

 ob.aat=(float)ob.tat/n;

 disp();

}

void roundrobin()

{

 clrscr();

 get();

 for(i=1,j=1,k=n;i<=ob.tbt;i++)

 {

  pa[i]=p[j];

  obp[p[j]].t=obp[p[j]].t+1;

  if(obp[p[j]].t==obp[p[j]].bt)

  {

   if(j==k)

   {

    p[j]='\0';

    j=j-1;

   }

   else

   {

    for(t=j;t<=k-1;t++)

    {

     p[t]=p[t+1];

    }

    p[t]='\0';

   }

   k=k-1;

   if(j!=p[k])

    goto l;

  }

  if(j>=k)

   j=1;

  else

   j++;

   l:

 }

 pa[i]='\0';

 cout<<"\nRound Robin Schedule Process Array: \n\n";

 i=1;

 while(pa[i]!='\0')

 {

  cout<<"P"<<pa[i]<<" ";

  i++;

 }

 for(i=1;i<=n;i++)

 {

  for(j=ob.tbt;j>0;j--)

  {

   if(pa[j]==i)

   {

    obp[i].wt=j-obp[i].bt;

    obp[i].at=obp[i].bt+obp[i].wt;

    break;

   }

  }

  ob.twt=ob.twt+obp[i].wt;

  ob.tat=ob.tat+obp[i].at;

 }

 ob.awt=(float)ob.twt/n;

 ob.abt=(float)ob.tbt/n;

 ob.aat=(float)ob.tat/n;

 disp();

}

void main()

{

  int ch;

  clrscr();

  cout<<"\nCPU SCHEDULING "<<endl;

  cout<<"\n1.FCFS\n2.SJF\n3.Round Robin\n4.Exit\n\n";

  do

  {

     cout<<"\n\nEnter your choice:"<<endl;

     cin>>ch;

     switch(ch)

     {

       case 1: fcfs();

                 break;

       case 2: sjf();

                 break;

       case 3: roundrobin();

                 break;

     }

  }while(ch!=4);

  getch();

}

OUPUT:

CPU SCHEDULING

1.FCFS

2.SJF

3.Round Robin

4.Exit

Enter your choice:

1

Enter the number of process: 3

Enter the Burst Time for P1 : 3

Enter the Burst Time for P2 : 2

Enter the Burst Time for P3 : 1

FCFS Process Array:

P1      P2      P3

Burst time for P1       : 3

Waiting time for P1     : 0

TurnAround time for P1  : 3

Burst time for P2       : 2

Waiting time for P2     : 3

TurnAround time for P2  : 5

Burst time for P3       : 1

Waiting time for P3     : 5

TurnAround time for P3  : 6

Total Burst time  : 6

Total Waiting time: 8

Total Around time : 14

Average Burst time     : 2

Average Waiting time   : 2.666667

Average TurnAround time: 4.666667

Enter your choice:

2

Enter the number of process: 3

Enter the Burst Time for P1 : 4

Enter the Burst Time for P2 : 3

Enter the Burst Time for P3 : 7

Shortest Job First Process Array:

P2      P1      P3

Burst time for P1       : 4

Waiting time for P1     : 3

TurnAround time for P1  : 7

Burst time for P2       : 3

Waiting time for P2     : 0

TurnAround time for P2  : 3

Burst time for P3       : 7

Waiting time for P3     : 7

TurnAround time for P3  : 14

Total Burst time  : 14

Total Waiting time: 10

Total Around time : 24

Average Burst time     : 4.666667

Average Waiting time   : 3.333333

Average TurnAround time: 8

Enter your choice:

3

Enter the number of process: 3

Enter the Burst Time for P1 : 9

Enter the Burst Time for P2 : 3

Enter the Burst Time for P3 : 1

Round Robin Schedule Process Array:

P1 P2 P3 P1 P2 P1 P2 P1 P1 P1 P1 P1 P1

Burst time for P1       : 9

Waiting time for P1     : 4

TurnAround time for P1  : 13

Burst time for P2       : 3

Waiting time for P2     : 4

TurnAround time for P2  : 7

Burst time for P3       : 1

Waiting time for P3     : 2

TurnAround time for P3  : 3

Total Burst time  : 13

Total Waiting time: 10

Total Around time : 23

Average Burst time     : 4.333333

Average Waiting time   : 3.333333

Average TurnAround time: 7.666667

Enter your choice:

4