SSTF disk scheduling
Program to implement SSTF disk scheduling algorithm
/* Variable description : req[] - array for taking the request, index[] - array for store the distance of
each request from the current position, a[] - array to store the final sequence in which requests should be fulfilled, min - to find the nearest request from the index array, mini - stores the index of nearest request, move - to calculate total head movement, cp1 - to save the initial value of current position */
#include<math.h>
#include<stdio.h>
int main()
{
int i,n,k,req[50],mov=0,cp,index[50],min,a[50],j=0,mini,cp1;
printf("enter the current position\n");
scanf("%d",&cp);
printf("enter the number of requests\n");
scanf("%d",&n);
cp1=cp;
printf("enter the request order\n");
for(i=0;i<n;i++)
{
scanf("%d",&req[i]);
}
for(k=0;k<n;k++){
for(i=0;i<n;i++)
{
index[i]=abs(cp-req[i]); // calculate distance of each request from current position
}
// to find the nearest request
min=index[0];
mini=0;
for(i=1;i<n;i++)
{
if(min>index[i])
{
min=index[i];
mini=i;
}
}
a[j]=req[mini];
j++;
cp=req[mini]; // change the current position value to next request
req[mini]=999;} // the request that is processed its value is changed so that it is not processed again
printf("Sequence is : ");
printf("%d",cp1);
mov=mov+abs(cp1-a[0]); // head movement
for(i=1;i<n;i++)
{
mov=mov+abs(a[i]-a[i-1]); ///head movement
printf(" -> %d",a[i]);
}
printf("\n");
printf("total head movement = %d\n",mov);
}
