CSCAN-Disk-Scheduling.c

#include<stdio.h>
#include<stdlib.h>

void cscan(int Ar[20], int n, int start);
void sort(int Ar[20], int n);

int main() {
    int diskQueue[20], n, start, i, max;
    printf("Enter the size of Queue: ");
    scanf("%d", &n);
    printf("Enter the Queue: ");
    for(i=1;i<=n;i++) {                                     /* head element to be read */ 
        scanf("%d",&diskQueue[i]);
    }
    printf("Enter the initial head position: ");
    scanf("%d", &start);                                
    diskQueue[0] = start;                                    /* injecting to the first position */
    ++n;
    sort(diskQueue, n);                                     /* total of n+1 elements */    
    cscan(diskQueue, n, start);

    return 0;
}

void cscan(int Ar[20], int n, int start) {
    int i, pos, diff, seekTime=0, current;
    // position of the disk to start seeking 
    for(i=0;i<n;i++) {                                      
        if(Ar[i]==start) {
            pos=i;
            break;
        }
    }
    // start seeking to the right
    printf("\nMovement of Cylinders\n");
    for(i=pos;i<n-1;i++) {
        diff = abs(Ar[i+1] - Ar[i]);
        seekTime+= diff;
        printf("Move from %d to %d with seek time %d\n", Ar[i], Ar[i+1], diff);
    }
    current=0;                                                                      /* start and end are same as circular, so start state i.e, 0*/
    // last element to 0, the first element
    printf("Move from %d to %d with seek time %d\n", Ar[i], current, 0);            /* head movement as cylinders are treated as a circular list (C-SCAN always goes back to the first track) */
    // start seeking to the right from 0
    for(i=0;i<pos;i++) {
        diff = abs(Ar[i] - current);
        seekTime+= diff;
        printf("Move from %d to %d with seek time %d\n", current, Ar[i], diff);
        current = Ar[i];
    }
    printf("\nTotal Seek Time: %d", seekTime);
    // average of entered elements(n-1) excluding head
    printf("\nAverage Seek Time = %f",(float) seekTime/(n-1));                      /* Note: Even though six seeks were performed using the C-SCAN algorithm, only five I/Os were actually done. */
    printf("\n");
}

void sort(int Ar[20], int n) {
    int i, j, tmp;
    for(i=0;i<n-1;i++) {
        for(j=0;j<n-1-i;j++) {
            if(Ar[j]>Ar[j+1]) {
                tmp = Ar[j];
                Ar[j] = Ar[j+1];
                Ar[j+1] = tmp;
            }
        }
    }
}