#include "roundrobin.h"
#include<iomanip>
#include<iostream>
using namespace std;
roundrobin::roundrobin(void)
{
    rq=w=t=NULL;
}

roundrobin::~roundrobin(void)
{
    if(rq!=NULL)
    {
        delete[] rq;
        delete[] w;
        delete[] t;
        delete[] a;
    }
}
int roundrobin::read()//read input from the user
{
    int i;
    cout<<"Enter number of processes:";
    cin>>n;
    if(rq!=NULL)
    {
        delete[] rq;
        delete[] w;
        delete[] t;
    }
    try
    {
        rq=new int[n];
        w=new int[n];
        t=new int[n];
        a=new int[n];
    }
    catch(bad_alloc &ba)
    {
        cerr<<ba.what()<<endl;
        exit(1);
    }
    cout<<"Enter arrival times:\n";
    for(i=0;i<n;i++)
    {
        cin>>a[i];
    }
    cout<<"Enter request times:\n";
    for(i=0;i<n;i++)
    {
        cin>>rq[i];
        w[i]=t[i]=0;
    }
    cout<<"Enter time quantum:";
    cin>>q;
    return 1;
}
void roundrobin::calc()//to calculate turn-around and wait times of all processes and the ordering
{
    int j=0;
    int time;
    int k;
    int i;
    int *r;//remaining times
    try
    {
        r=new int[n];
    }
    catch(bad_alloc &ba)
    {
        cerr<<ba.what()<<endl;
        exit(1);
    }
    for(i=0;i<n;i++)    r[i]=rq[i];
    bool f=false;//flag to indicate whether any process was scheduled as i changed from 0 to n-1 in the next for loop
    int sp=0;//time spent
    for(i=0;j<n;i=(i+1)%n)//while there are uncompleted processes
    {
        if(r[i]>0&&sp>=a[i])//find the next uncompleted process which has already or just arrived
        {
            f=true;
            if(r[i]<=q)//if the process requests for time less than the quantum
                time=r[i];//time to be alloted in this turn is the complete requested time
            else    time=q;//else, it is the quantum time
            //schedule the process
            t[i]+=time,r[i]-=time,order.push_back(i+1);
            if(r[i]==0) j++;//if the process has got completed, increment j
            for(k=0;k<n;k++)
                if(r[k]!=0&&k!=i&&a[k]<sp+time)//for all other arrived processes incompleted after scheduling this process
                    if(!(a[k]<=sp))//if they arrived while scheduling this process
                        w[k]+=sp+time-a[k],t[i]+=sp+time-a[k];//account for the time they spent waiting while the process was being scheduled
                    else
                        w[k]+=time,t[k]+=time;//add time to their wait times and turn-around times
            sp+=time;
            continue;
        }
        if(i==n-1)
        {
            if(!f)
            //now there are no more arrived processes to be scheduled
            //so change sp to the arrival time of next arriving process
            {
                int it;
                int diff=0;//diff between present time spent and arrivaltime of next arriving process
                for(it=0;it<n;it++)
                    if(sp<a[it])//if process has'nt yet arrived
                    {
                        if(diff==0) diff=a[it]-sp;
                        else if(diff>a[it]-sp)  diff=a[it]-sp;
                    }
                sp+=diff;
            }
            f=false;
        }
    }
    delete[] r;
}
void roundrobin::display()
{
    int i;
    float tav=0;//average turn-around time
    float wav=0;//average wait time
    for(i=0;i<n;i++)
        tav+=t[i],wav+=w[i];
    tav/=n,wav/=n;
    cout<<"Scheduling order:\n";
    list<int>::iterator oi;
    for(oi=order.begin();oi!=order.end();oi++)
        cout<<*oi<<"\t";
    cout<<"\nAverage turn-around time = "<<tav<<endl<<"Average wait time = "<<wav<<endl;
}