C++ Program For LOOK Disk Scheduling Algorithm | C++ Programming

Look Disk Scheduling Algorithm

• LOOK Algorithm is an improved version of the SCAN Algorithm.
• Head starts from the first request at one end of the disk and moves towards the last request at the other end servicing all the requests in between.
• After reaching the last request at the other end, the head reverses its direction.
• It then returns to the first request at the starting end servicing all the requests in between.
• The same process repeats.

C++ program for LOOK Disk Scheduling Algorithm

#include <iostream>
#include <stdlib.h>
using namespace std;
class look_disk
{
    int ref[100];
    int ttrk, cur, size, prev;
    int sort();
public:
    void getdata();
    void total_move();
};
int look_disk::sort()
{
    int temp;
    for (int i = 0; i < size - 1; i++)
        for (int y = 0; y < size - 1; y++)
            if (ref[y] > ref[y + 1])
            {
                temp = ref[y + 1];
                ref[y + 1] = ref[y];
                ref[y] = temp;
            }
    for (int i = 0; i < size; i++)
        if (ref[i] > cur)
            return i;
    return size;
}
void look_disk::getdata()
{
    cout << "Enter total number of tracks : ";
    cin >> ttrk;
    ttrk--;
    cout << "Enter the current position of head : ";
    cin >> cur;
    cout << "Enter previous position of head : ";
    cin >> prev;
    cout << "Enter the size of queue : ";
    cin >> size;
    cout << "Enter the request for tracks : ";
    for (int i = 0; i < size; i++)
        cin >> ref[i];
}
void look_disk::total_move()
{
    int num = cur, move = 0, ind, dir = cur - prev;
    ind = sort();
    if (dir > 0)
    {
        for (int i = ind; i < size; i++)
        {
            move += ref[i] - num;
            num = ref[i];
        }
        if (ind != 0)
        {
            if (ind == size)
                move += num - ref[ind - 1];
            else
                move += ref[size - 1] - ref[ind - 1];
            num = ref[ind - 1];
            for (int i = ind - 2; i >= 0; i--)
            {
                move += num - ref[i];
                num = ref[i];
            }
        }
    }
    else
    {
        for (int i = ind - 1; i >= 0; i--)
        {
            move += num - ref[i];
            num = ref[i];
        }
        if (ind == 0)
            move += ref[ind] - num;
        else if (ind != size)
            move += ref[ind] - ref[0];
        num = ref[ind];
        for (int i = ind + 1; i < size; i++)
        {
            move += ref[i] - num;
            num = ref[i];
        }
    }
    cout << "Total head movements : " << move;
}
int main()
{
    look_disk look;
    look.getdata();
    look.total_move();
    return 0;
}

You May Also Like:

C Program for SCAN disk scheduling algorithm 

C program for First Come First Serve (FCFS) disk scheduling algorithm | C Programming

C program for Shortest Seek Time Next Disk Scheduling Algorithm | C Programming

C++ program for LOOK Disk Scheduling Algorithm | C++ Programming

C Program for C-SCAN Disk Scheduling Algorithm | C Programming

C++ Program For C-LOOK Disk Scheduling Algorithm | C++ Programming