ssos10.c

#include<stdio.h>
#include<stdlib.h>
struct proc
{
	int id;
int arrival;
int burst;
int rem;
int wait;
int finish;
int turnaround;
float ratio;
}process[10];  //structure to hold the process information
struct proc temp;
int no;

int chkprocess(int);
int nextprocess();
void roundrobin(int, int, int[], int[]);
void srtf(int);

main()
{
	int n,tq,choice;       
int bt[10],st[10],i,j,k;
	for(; ;)
	{
		printf("Enter the choice  \n");
		printf(" 1. Round Robin\n 2. SRT\n 3. Exit \n");
		scanf("%d",&choice);
		switch(choice)
		{
			case 1:
				printf("Round Robin scheduling algorithm\n");
				printf("Enter number of processes:\n");
				scanf("%d",&n);
				printf("Enter burst time for sequences:");
				for(i=0;i<n;i++)
				{
					scanf("%d",&bt[i]);
					st[i]=bt[i];	//service time
				}
				printf("Enter time quantum:");
				scanf("%d",&tq);
				roundrobin(n,tq,st,bt);
break;

			case 2: 
				printf("\n \n ---SHORTEST REMAINING TIME NEXT---\n \n ");
				printf("\n \n Enter the number of processes: ");
				scanf("%d", &n);
				srtf(n);
				break;
				
			case 3: exit(0);
		}// end of switch
	}// end of for
}//end of main()

void  roundrobin(int n,int tq,int st[],int bt[])
{    		    
	int time=0;
int tat[10],wt[10],i,count=0,swt=0,stat=0,temp1,sq=0,j,k;
float awt=0.0,atat=0.0;
while(1)
{
	for(i=0,count=0;i<n;i++)
     	{
			temp1=tq;
			if(st[i]==0) // when service time of a process equals zero we continue to next process
			{             
				count++;   //then count value is incremented 
				continue;
			}
			if(st[i]>tq) // when service time of a process greater than time quantum then time
				st[i]=st[i]-tq;     //quantum value subtracted from service time
			else
				if(st[i]>=0)              
				{
					temp1=st[i];      // temp1 stores the service time of a process
					st[i]=0;               // making service time equals 0
				}
			sq=sq+temp1;      // utilizing temp1 value to calculate turnaround time
			tat[i]=sq;               // turn around time
		}  //end of for
		if(n==count)      // it indicates all processes  have completed their task because the count value 
			break;                       // incremented when service time equals 0
	} //end of while
	for(i=0;i<n;i++)       // to calculate the wait time and turnaround time of each process
	{       
		wt[i]=tat[i]-bt[i];     // waiting time calculated from the turnaround time - burst time
		swt=swt+wt[i];       // summation of  wait time 
		stat=stat+tat[i];      // summation of turnaround time
	}
	awt=(float)swt/n;          // average wait time
	atat=(float)stat/n;         // average turnaround time
	printf("Process_no	Burst time	Wait time	Turn around time\n");
	for(i=0;i<n;i++)
		printf("%d\t\t%d\t\t%d\t\t%d\n",i+1,bt[i],wt[i],tat[i]);
	printf("Avg wait time is %f\n Avg turn around time is %f\n",awt,atat);
}// end of Round Robin


int chkprocess(int s)         // function to check process remaining time is zero or not
{
	int i;
	for(i = 1; i <= s; i++)
	{
		if(process[i].rem != 0)
			return 1;
	}
	return 0;
} // end of chkprocess    
           
int nextprocess()        // function to identify the next process to be executed
{
int min, l, i;
min = 32000;   //any limit assumed
for(i = 1; i <= no; i++)
{
		if( process[i].rem!=0 && process[i].rem < min)
	{
		min = process[i].rem;
		l = i;
	}
}
return l;
}  // end of nextprocess

void srtf(int n)
{
	int i,j,k,time=0;
	float tavg,wavg;
	for(i = 1; i <= n; i++)
	{
	process[i].id = i;
	printf("\n\nEnter the arrival time for process %d: ", i);
	scanf("%d", &(process[i].arrival));
	printf("Enter the burst time for process %d: ", i);
	scanf("%d", &(process[i].burst));
	process[i].rem = process[i].burst;
}
for(i = 1; i <= n; i++)
{
	for(j = i + 1; j <= n; j++)
	{
		if(process[i].arrival > process[j].arrival)   //  sort  arrival time of a process
		{
			temp = process[i];
			process[i] = process[j];
			process[j] = temp;
		}
	}
}

no = 0;
j = 1;
	while(chkprocess(n) == 1)
{
	if(process[no + 1].arrival == time)
	{
		no++;
		if(process[j].rem==0)          
			process[j].finish=time;
		j = nextprocess(); 
	}
	if(process[j].rem != 0)             // to calculate the waiting time of  a process
	{
		process[j].rem--;
		for(i = 1; i <= no; i++)
		{
			if(i != j && process[i].rem != 0)
				process[i].wait++;             
		}
	}
            else
	{
		process[j].finish = time;
		j=nextprocess();
		time--;
		k=j;
	}
	time++;
}
process[k].finish = time;
printf("\n\n\t\t\t---SHORTEST REMAINING TIME FIRST---");
printf("\n\n Process  Arrival  Burst   Waiting  Finishing turnaround  Tr/Tb \n");
printf("%5s %9s %7s %10s %8s %9s\n\n", "id", "time", "time", "time", "time", "time");
for(i = 1; i <= n; i++)
{
		process[i].turnaround = process[i].wait + process[i].burst; // calc of turnaround 
		process[i].ratio = (float)process[i].turnaround / (float)process[i].burst;        

		printf("%5d %8d %7d  %8d %10d %9d %10.1f ", process[i].id, process[i].arrival,
		process[i].burst, process[i].wait, process[i].finish, process[i].turnaround, process[i].ratio);
		tavg=tavg+ process[i].turnaround;    //summation of turnaround time
		wavg=wavg+process[i].wait;           // summation of waiting time
		printf("\n\n");
}

tavg=tavg/n;        // average turnaround time
wavg=wavg/n;     // average wait time
printf("tavg=%f\t wavg=%f\n",tavg,wavg);
}// end of srtf