Question

In C++, assuming you have the following incomplete code:

#include<iostream>
#include <unistd.h>
using namespace std;
// Structure for storing the process data
struct procData
{
char pname[5]; // Name of a process
int arrivt; //Arrival time of a process
int pburst; // Burst time of a process
int endtime; // Exit time/ Leaving time of a process
int remburst; // Remaining burst time of a process
int readyFlag; // boolean, Flag for maintaining the process status
};
// Global variable
int qTime; // Time quantum
// Function prototypes
procData* procIPData(int ); // Input the processes data in the global array
void calculate(procData*, int); // Calculate the average waiting and turn around time
void display_waittime(procData*, int); // Display the average and waiting and turn around time
int main()
{
procData *q;
int noProcess; // Number of processes
cout << "Enter Total no. of processes" << endl;
cin >> noProcess;
q = procIPData(noProcess);
calculate(q, noProcess);
display_waittime(q, noProcess);
return 0;
}

procData* procIPData(int noProc)
{
procData *a = new procData[noProc];
for (int i = 0; i < noProc; i++)
{
cout << "Enter process name:" << endl;
cin >> a[i].pname;
cout << "Enter process burst time:" << endl;
cin >> a[i].pburst;
cout << "Enter process arrival time:" << endl;
cin >> a[i].arrivt;
a[i].remburst = a[i].pburst;
a[i].endtime = 0;
a[i].readyFlag = 0;
}
cout << "Enter the time quantum/Time Slice:" << endl;
cin >> qTime;
return a;
}
void calculate(procData* a, int noProc)
{
// To be completed
}
void display_waittime(procData* a, int noProc)
{
int totalTA = 0, totalWait = 0, ta = 0, tw = 0;
for (int i = 0; i < noProc; i++)
{
ta = a[i].endtime - a[i].arrivt;
tw = ta - a[i].pburst;
cout << endl << "Waiting time for Process " << a[i].pname << " is " << tw << endl;
totalTA = totalTA + ta;
totalWait = totalWait + tw;
}
cout << "Average waiting time = " << ((float) totalWait / (float) noProc) << endl;
cout << "Average turnaround time= " << ((float) totalTA / (float) noProc) << endl;
}

Complete the C++ program so that it displays the Gantt chart, average waiting time and average turnaround time for the list of process using pre-emptive Round-robin CPU scheduling strategy. The program takes the CPU burst times and arrival times for the given list of processes as input.

Answer 1

The solution for above problem is as follows:-

Code-

#include<iostream>
#include <unistd.h>
#include<algorithm>
using namespace std;
// Structure for storing the process data
struct procData
{
   char pname[5]; // Name of a process
   int arrivt; //Arrival time of a process
   int pburst; // Burst time of a process
   int endtime; // Exit time/ Leaving time of a process
   int remburst; // Remaining burst time of a process
   int readyFlag; // boolean, Flag for maintaining the process status
};
// Global variable
int qTime; // Time quantum
// Function prototypes
procData* procIPData(int noProc); // Input the processes data in the global array
void calculate(procData*, int); // Calculate the average waiting and turn around time
void display_waittime(procData*, int); // Display the average and waiting and turn around time
int main()
{
   procData *q;
   int noProcess; // Number of processes
   cout << "Enter Total no. of processes" << endl;
   cin >> noProcess;
   q = procIPData(noProcess);
   calculate(q, noProcess);
   display_waittime(q, noProcess);
   return 0;
}

procData* procIPData(int noProc)
{
   procData *a = new procData[noProc];
   for (int i = 0; i < noProc; i++)
   {
       cout << "Enter process name:" << endl;
       cin >> a[i].pname;
       cout << "Enter process burst time:" << endl;
       cin >> a[i].pburst;
       cout << "Enter process arrival time:" << endl;
       cin >> a[i].arrivt;
       a[i].remburst = a[i].pburst;
       a[i].endtime = 0;
       a[i].readyFlag = 0;
   }
   cout << "Enter the time quantum/Time Slice:" << endl;
   cin >> qTime;
   return a;
}
bool compare(procData a,procData b){
   return a.arrivt<b.arrivt;
}
void calculate(procData* a, int noProc)
{
   sort(a,a+noProc,compare);//Sorting processes accoridng to arrival time;
   int time,count,flag=0,remain=noProc;
   for(time=0,count=0;remain!=0;)
   {
       if(a[count].remburst<=qTime && a[count].remburst>0)
       {
           time+=a[count].remburst;
           a[count].remburst=0;
           flag=1;
       }
       else if(a[count].remburst>0)
       {
           a[count].remburst-=qTime;
           time+=qTime;
       }
       if(a[count].remburst==0 && flag==1)
       {
           remain--;
           a[count].endtime=time;
           flag=0;
       }
       if(count==noProc-1)
           count=0;
       else if(a[count+1].arrivt<=time)
           count++;
       else
           count=0;
   }
}
void display_waittime(procData* a, int noProc)
{
   int totalTA = 0, totalWait = 0, ta = 0, tw = 0;
   for (int i = 0; i < noProc; i++)
   {
       ta = a[i].endtime - a[i].arrivt;
       tw = ta - a[i].pburst;
       cout << endl << "Waiting time for Process " << a[i].pname << " is " << tw << endl;
       totalTA = totalTA + ta;
       totalWait = totalWait + tw;
   }
   cout << "Average waiting time = " << ((float) totalWait / (float) noProc) << endl;
   cout << "Average turnaround time= " << ((float) totalTA / (float) noProc) << endl;
}

Code screenshots-

Outputs-

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