C++ Code for Project :URGENT

[sharma]

I have this code to implement Go Baack N ARQ in networks. I need to put real time delay of frames i.e a separate timer for each frame instead of a single timer for all. Furthermore i need to add a case of Negative Acknowledgement being sent by the receiver if the frame was lost and the sender class should resend only that very frame again.There is a need to modify this code for my purpose. Please do help me ive tried this so many times and is a part of my project.I need to complete it urgently.

#include<iostream.h>

#include<conio.h>

#include<math.h>

class sender

{
      public :
int size,sf,sn,t,a[500],q[500],w,ff,sent  ;
sender(){}//default constructor
sender(int x,int aa)//parameterised constructor
{ 
 ff=aa;//ff and aa = total no of frames 
size=pow(2,x)-1;//size of sliding window
sn=0;//next frame to sent
sf=0;//first outstanding frame
w=0;//count of frames 
if(aa<=5)
t=2;//timer (decremented by 1 after a frame is sent)
else
t=5;//timer (decremented by 1 after a frame is sent)
sent=0;
for(int i=0;i<aa;i=i+size+1)//to assign sequence no to frames
{ 
for(int j=0;j<=size;j++)
{
if(i+j < aa)
a[i+j]=j;
}
}
} 
void reqstsend()//to send frames
{
if(w<ff)//check whether the no. of frame sent is less than total no of frames
{
if(t<=0 )//check for time out
{
cout<<endl<<"Caution : Timer out"<<endl;
timeout();
}
else if((sn-sf)>=size || sf==sn+1 )
{
cout<<endl<<"Caution : Window is full"<<endl;
t--;

}
  
/*else if(sn == size)//special case when sn==size sn should be =0
{
cout<<endl<<"frame F"<<sn<<" sent..."<<endl;
sn=0;
t--;
w++;
sent++;
show();
cout<<endl<<"frames sent :- ";
for(int i=0;i<w;i++)
{ 
        cout<<" "<<a[i]<<" ";
}
}*/
else//normal sending
{
cout<<endl<<"Frame F"<<sn<<" sent..."<<endl;
sn++;
t--;
w++;
sent++;
show();
cout<<endl<<"Frames sent :- ";
for(int i=0;i<w;i++)
{       
cout<<" "<<a[i]<<" ";
}
}
}
else
cout<<endl<<" ***All Frames Sent***"<<endl;
}
void arivack(int y)//recieving acknowledgement
{
sf=y;
t=sn-sf;
}
void timeout()
{
sn=sf;
if(ff<5) 
{
  t=2;
w=w-2;
sent=sent-2;
}
Else
{    
t=5;
w=w-5;
sent=sent-5;
}
}
void sdisplay()//displaying frames initially
{
cout<<endl<<"Frames :- ";
for(int i=0;i<ff;i++)
cout<<" "<<a[i]<<" ";
cout<<endl<<endl<<"sn = "<<sn<<endl<<"sf = "<<sf<<endl;
}
void show()
{
     cout<<endl<<"No of frames sent ="<<sent<<endl;
}
};//class sender ends
 
class reciever : public sender
{
public :
int rn,b[500],c,reci;
sender *s;//sender class pointer
reciever(sender *y,int q)//contructor to initialise variables and element of array
{
reci =0;
rn=size;//next expected frame
c=0;//counter
for(int i=0;i<q;i++)
b[i]=0;
s=y;
}
void arivnot(int x)
{
if(rn == x)//recieve in order
{
if(rn != s->size)//recieving frames
{
b[c]=rn;
c++;
rn++;
}
else//special case when rn =size, then rn should be =0
{
b[c]=rn;
c++;
rn=0;
}
}
}
void sendack(int z)
{
cout<<endl<<"Acknowledgement A"<<z<<" sent"<<endl;
s->arivack(z); 
}

void sendlostack(int z)
{
cout<<endl<<"Acknowledgement A"<<z<<" sent"<<endl;
}

void rdisplay()
{     
cout<<endl<<"No of frames recieved ="<<c<<endl;
cout<<endl<<"Frames recieved :- ";
for(int i=0;i<c;i++)
cout<<" "<<b[i]<<" ";
cout<<endl<<endl<<"rn = "<<rn<<endl<<endl;
}
};//class reciever ends   

int main()
 {
int m,x=3,h,y,counter=0;
cout<<endl<<"Enter the value of sequence no. (m no of bits) => ";
cin>>m;
cout<<"Sliding window size ="<<pow(2,m-1)<<endl;
cout<<"Recieving window size ="<<pow(2,m-1)<<endl;
cout<<"Enter the total no of frames you want to send "<<endl;
cin>> h;
sender pqr(m,h),*g=&pqr;
reciever rec(g,h),*r=&rec;
while(1)
{
                 if(counter==0)
{
                      cout<<endl<<"Press 1 for going to sender side"<<endl
                      <<"Press 0 to exit"<<endl <<"enter code => ";
                     cin>>x;
if(x==2)
x=8;
counter++;
if(x!=1)
counter--;
}
else
{
             cout<<endl<<"Press 1 for going to sender side"<<endl <<"Press 2 for going to receiver             side"<<endl <<"Press 0 to exit"<<endl  <<"enter code => ";
cin>>x;
}
switch(x)
{
case 1 : while(y != 3)
 {

            pqr.sdisplay();
            cout<<endl<<"Press 1 to send frame"<<endl <<"Press 2 to send frame (lost or incorrect)"<<endl
             <<"Press 3 to go back"<<endl<<" => ";
             cin>>y;
switch(y)

             {

             case 1 :
        
                  pqr.reqstsend();

                  if(pqr.sn == 0)

                  r->arivnot(pqr.size);

                  else

                  r->arivnot(pqr.sn-1);
    
                  break;

             case 2 : pqr.reqstsend();

                  break;

             case 3 :
                  
                   break;

             default :
                     
                   cout<<endl<<"Caution !!! error in code !!!  please enter right choice "<<endl;

                   break;

             }

             }

             y=0;

             break;

case 2 : while(y != 3)

             {

             r->rdisplay();

             cout<<endl<<"Press 1 to send Acknowledgement"<<endl

                        <<"Press 2 to send ack (lost)"<<endl
                        
                         <<"Press 3 to go back"<<endl

                         <<" => ";

             cin>>y;

             switch(y)

             {

             case 1 : 
                  
                         r->sendack(rec.rn);  // cout<<endl<<"no of frames sent ="<<pqr.sent<<endl;

                         break;
              
             case 2:
                   
                         r->sendlostack(rec.rn);
                   
                   break;

             case 3:
                  
                   break;

             default : 
                     cout<<endl<<"Caution !!! error in code !!!"<<endl;

                         break;

             }

             };

             y=0;

             break;

case 0 :
    
     exit(0);
    
      break;

default : 
        
        cout<<endl<<"Caution !!! error in code !!!"<<endl;

                break;

}

}

getch();

return 0;

}