Added working SJF files

Author: anuraagbaishya

OS Lab/CPU Scheduling/non-pre-SJF.c

@@ -0,0 +1,95 @@
+#include<stdio.h>
+int main()
+{
+int i,n,p[10]={1,2,3,4,5,6,7,8,9,10},min,k=1,btime=0;
+int bt[10],temp,j,at[10],wt[10],tt[10],ta=0,sum=0;
+float wavg=0,tavg=0,tsum=0,wsum=0;
+printf(" -------Shortest Job First Scheduling ( NP )-------\n");
+printf("\nEnter the No. of processes :");
+scanf("%d",&n);
+ 
+for(i=0;i<n;i++)
+{
+printf("\tEnter the burst time of %d process :",i+1);
+scanf(" %d",&bt[i]);
+printf("\tEnter the arrival time of %d process :",i+1);
+scanf(" %d",&at[i]);
+}
+ 
+/*Sorting According to Arrival Time*/
+ 
+for(i=0;i<n;i++)
+{
+for(j=0;j<n;j++)
+{
+if(at[i]<at[j])
+{
+temp=p[j];
+p[j]=p[i];
+p[i]=temp;
+temp=at[j];
+at[j]=at[i];
+at[i]=temp;
+temp=bt[j];
+bt[j]=bt[i];
+bt[i]=temp;
+}
+}
+}
+ 
+/*Arranging the table according to Burst time,
+Execution time and Arrival Time
+Arrival time <= Execution time
+*/
+ 
+for(j=0;j<n;j++)
+{
+btime=btime+bt[j];
+min=bt[k];
+for(i=k;i<n;i++)
+{
+if (btime>=at[i] && bt[i]<min)
+{
+temp=p[k];
+p[k]=p[i];
+p[i]=temp;
+temp=at[k];
+at[k]=at[i];
+at[i]=temp;
+temp=bt[k];
+bt[k]=bt[i];
+bt[i]=temp;
+}
+}
+k++;
+}
+wt[0]=0;
+for(i=1;i<n;i++)
+{
+sum=sum+bt[i-1];
+wt[i]=sum-at[i];
+wsum=wsum+wt[i];
+}
+ 
+wavg=(wsum/n);
+for(i=0;i<n;i++)
+{
+ta=ta+bt[i];
+tt[i]=ta-at[i];
+tsum=tsum+tt[i];
+}
+ 
+tavg=(tsum/n);
+ 
+printf("************************");
+printf("\n RESULT:-");
+printf("\nProcess\t Burst\t Arrival\t Waiting\t Turn-around" );
+for(i=0;i<n;i++)
+{
+printf("\n p%d\t %d\t %d\t\t %d\t\t\t%d",p[i],bt[i],at[i],wt[i],tt[i]);
+}
+ 
+printf("\n\nAVERAGE WAITING TIME : %f",wavg);
+printf("\nAVERAGE TURN AROUND TIME : %f",tavg);
+return 0;
+}

OS Lab/CPU Scheduling/preemSJF.c

@@ -0,0 +1,45 @@
+#include <stdio.h>
+ 
+int main()
+{
+int arrival_time[10], burst_time[10], temp[10];
+int i, smallest, count = 0, time, limit;
+double wait_time = 0, turnaround_time = 0, end;
+float average_waiting_time, average_turnaround_time;
+printf("\nEnter the Total Number of Processes:\t");
+scanf("%d", &limit);
+printf("\nEnter Details of %d Processes\n", limit);
+for(i = 0; i < limit; i++)
+{
+printf("\nEnter Arrival Time:\t");
+scanf("%d", &arrival_time[i]);
+printf("Enter Burst Time:\t");
+scanf("%d", &burst_time[i]);
+temp[i] = burst_time[i];
+}
+   burst_time[9] = 9999;  
+for(time = 0; count != limit; time++)
+{
+   smallest = 9;
+   for(i = 0; i < limit; i++)
+   {
+   if(arrival_time[i] <= time && burst_time[i] < burst_time[smallest] && burst_time[i] > 0)
+{
+   smallest = i;
+}
+   }
+   burst_time[smallest]--;
+   if(burst_time[smallest] == 0)
+   {
+   count++;
+   end = time + 1;
+   wait_time = wait_time + end - arrival_time[smallest] - temp[smallest];
+   turnaround_time = turnaround_time + end - arrival_time[smallest];
+   }
+}
+average_waiting_time = wait_time / limit;
+average_turnaround_time = turnaround_time / limit;
+printf("\n\nAverage Waiting Time:\t%lf\n", average_waiting_time);
+     printf("Average Turnaround Time:\t%lf\n", average_turnaround_time);
+     return 0;
+}