Write the simulation program for preemptive scheduling algorithm using Priority.

/* Write the simulation program for preemptive scheduling algorithm using Priority. The arrival time, first CPU bursts and process priority of different jobs should be input to the system. The output should give the Gantt chart and Turnaround Time for each process and average times.*/
#include<stdio.h>

struct Input
{
char pname[10];
int  bt,at,ct,tbt,p;
}tab[5];

struct Sequence
{
int start,end;
char pname[10];
}seq[100],seq1[20];

int finish,time,n,k,prev,q;

void getinput()
{
int i;
clrscr();
printf("\nEnter No.of Processes:");
scanf("%d",&n);

for(i=0;i<n;i++)
{
printf("Process name:");
scanf("%s",tab[i].pname);
printf("Burst time:");
scanf("%d",&tab[i].bt);
printf("Arrival time:");
scanf("%d",&tab[i].at);
printf("Enter priority: ");
scanf("%d",&tab[i].p);

tab[i].tbt = tab[i].bt;
}
}
void printinput()
{
int i;

printf("\nProcess\tBT\tAT\tpriority");
for(i=0;i<n;i++)
printf("\n%s\t%d\t%d\t%d",tab[i].pname,tab[i].tbt,tab[i].at,tab[i].p);
getch();
}

void bubble()
{
struct Input t;
int i,j;
for(i=0;i<n;i++)
for(j=0;j< (n-1)-i;j++)
if(tab[j].at>tab[j+1].at)
{
t = tab[j];
tab[j] = tab[j+1];
tab[j+1] = t;
}
}
int getmin(int t)
{
int i,mini,min=99;
for(i=0;i<n;i++)
if(tab[i].at<=t && tab[i].tbt!=0 && tab[i].p<min)
{
min = tab[i].p;
mini = i;
}
return mini;
}



void printoutput()
{
int i;
float AvgTAT=0,AvgWT=0;
printf("\nProcess\tAT\tBT\tCT\tTAT\tWT");
for(i=0;i<n;i++)
{
printf("\n%s\t%d\t%d\t%d\t%d\t%d",tab[i].pname,
 tab[i].at,
 tab[i].bt,
 tab[i].ct,
 tab[i].ct-tab[i].at,
 tab[i].ct-tab[i].at-tab[i].bt);
AvgTAT += tab[i].ct-tab[i].at;
AvgWT += tab[i].ct-tab[i].at-tab[i].bt;
}
AvgTAT/=n;
AvgWT/=n;
printf("\nAverage TAT = %f",AvgTAT);
printf("\nAverage WT = %f",AvgWT);
getch();
}

int arrived(int t)
{
int i;
for(i=0;i<n;i++)
if(tab[i].at<=t && tab[i].tbt!=0)
return 1;
return 0;
}

void processinput()
{
int i=0,j;
finish = k = 0;
while(finish!=n)
{
if(arrived(time))
{
     i=getmin(time);
time++;
tab[i].tbt--;
printinput();
seq[k].start=prev;
seq[k].end = time;
strcpy(seq[k++].pname,tab[i].pname);
prev = time;
tab[i].ct=time;
if(tab[i].tbt==0)
{
finish++;

}


}
else
{
time++;
seq[k].start=prev;
seq[k].end = time;
strcpy(seq[k++].pname,"*");
prev = time;
}

}
}

void ganttchart()
{
int i,j=1;
clrscr();
seq1[0] = seq[0];
for(i=1;i<k;i++)
{
if(strcmp(seq1[j-1].pname,seq[i].pname)==0)
seq1[j-1].end = seq[i].end;
else
seq1[j++] = seq[i];
}
for(i=0;i<j;i++)
printf("\n%d\t%s\t%d",seq1[i].start,seq1[i].pname,seq1[i].end);
getch();
}

void main()
{
int i;
getinput();
printf("\nEntered data-: ");
printinput();
bubble();
printf("\nData after sorting according to arrival time-: ");
printinput();
processinput();

printoutput();

ganttchart();


}