chit3

// C++ program for implementation of RR scheduling
#include<iostream>
using namespace std;

// Function to find the waiting time for all
// processes
void findWaitingTime(int processes[], int n,
int bt[], int wt[], int quantum)
{
// Make a copy of burst times bt[] to store remaining
// burst times.
int rem_bt[n];
for (int i = 0 ; i < n ; i++)
rem_bt[i] = bt[i];

int t = 0; // Current time 

// Keep traversing processes in round robin manner 
// until all of them are not done. 
while (1) 
{ 
	bool done = true; 

	// Traverse all processes one by one repeatedly 
	for (int i = 0 ; i < n; i++) 
	{ 
		// If burst time of a process is greater than 0 
		// then only need to process further 
		if (rem_bt[i] > 0) 
		{ 
			done = false; // There is a pending process 

			if (rem_bt[i] > quantum) 
			{ 
				// Increase the value of t i.e. shows 
				// how much time a process has been processed 
				t += quantum; 

				// Decrease the burst_time of current process 
				// by quantum 
				rem_bt[i] -= quantum; 
			} 

			// If burst time is smaller than or equal to 
			// quantum. Last cycle for this process 
			else
			{ 
				// Increase the value of t i.e. shows 
				// how much time a process has been processed 
				t = t + rem_bt[i]; 

				// Waiting time is current time minus time 
				// used by this process 
				wt[i] = t - bt[i]; 

				// As the process gets fully executed 
				// make its remaining burst time = 0 
				rem_bt[i] = 0; 
			} 
		} 
	} 

	// If all processes are done 
	if (done == true) 
	break; 
} 

}

// Function to calculate turn around time
void findTurnAroundTime(int processes[], int n,
int bt[], int wt[], int tat[])
{
// calculating turnaround time by adding
// bt[i] + wt[i]
for (int i = 0; i < n ; i++)
tat[i] = bt[i] + wt[i];
}

// Function to calculate average time
void findavgTime(int processes[], int n, int bt[],
int quantum)
{
int wt[n], tat[n], total_wt = 0, total_tat = 0;

// Function to find waiting time of all processes 
findWaitingTime(processes, n, bt, wt, quantum); 

// Function to find turn around time for all processes 
findTurnAroundTime(processes, n, bt, wt, tat); 

// Display processes along with all details 
cout << "PN\t "<< " \tBT "
	<< " WT " << " \tTAT\n"; 

// Calculate total waiting time and total turn 
// around time 
for (int i=0; i<n; i++) 
{ 
	total_wt = total_wt + wt[i]; 
	total_tat = total_tat + tat[i]; 
	cout << " " << i+1 << "\t\t" << bt[i] <<"\t "
		<< wt[i] <<"\t\t " << tat[i] <<endl; 
} 

cout << "Average waiting time = "
	<< (float)total_wt / (float)n; 
cout << "\nAverage turn around time = "
	<< (float)total_tat / (float)n; 

}

// Driver code
int main()
{
// process id's
int processes[] = { 1, 2, 3};
int n = sizeof processes / sizeof processes[0];

// Burst time of all processes 
int burst_time[] = {10, 5, 8}; 

// Time quantum 
int quantum = 2; 
findavgTime(processes, n, burst_time, quantum); 
return 0; 

}