Round_Robin.cpp

#include<iostream> 
using namespace std; 
// Function to find the waiting time 
void findWaitingTime(int processes[], int n, 
			int bt[], int wt[], int quantum) 
{ 

	int rem_bt[n]; 
	for (int i = 0 ; i < n ; i++) 
		rem_bt[i] = bt[i]; 
	int t = 0; // Current time
	
	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; 
					
					rem_bt[i] -= quantum; 
				} 
				
				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 << "Processes "<< " Burst time "
		<< " Waiting time " << " Turn around time\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; 
} 
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; 
}