diskscheduling.c

#include<stdio.h>
#include<stdlib.h>
void fcfs();
void scan();
void cscan();
void main()
{
    int op;
    while (1)
    {
        printf("\n1.FCFS 2.SCAN 3.C-SCAN 4.Exit \nEnter Your Choice: ");
        scanf("%d",&op);
        switch (op)
        {
           case 1:
              fcfs();
              break;
           case 2:
              scan();
              break;
           case 3:
              cscan();
              break;
           case 4:
              exit(0);
              break;
           default:
              printf("Wrong Choice!");
              break;
        }
    }
}
void fcfs()
{
    int initialHead, requests[20], i, currentHeadMovement, numRequests, totalHeadMovement=0;
    printf("Enter initial head position: ");
    scanf("%d", &initialHead);
    printf("Enter number of disk requests: ");
    scanf("%d", &numRequests);

    printf("Enter the disk requests: ");
    for (i = 1; i <= numRequests; i++)
        scanf("%d", &requests[i]);
    requests[0] = initialHead; 

    printf("\n---FCFS DISK SCHEDULING---\n");
    for (i = 0; i <numRequests; i++) 
    {
        currentHeadMovement = abs(requests[i] - requests[i + 1]);
        printf("Head movement from %d to %d: %d\n",requests[i],requests[i+1],currentHeadMovement);
        totalHeadMovement += currentHeadMovement;
    }
    printf("Total seek time is : %d\n", totalHeadMovement);
}
void scan()
{
    int requests[100], i, j, numRequests, totalHeadMovement = 0, initialHead, diskSize, currentMovement , ch;
    printf("Enter total disk size: ");
    scanf("%d", &diskSize);

    printf("Enter the number of Requests: ");
    scanf("%d", &numRequests);
    
    printf("Enter the Requests sequence: ");
    for (i = 0; i < numRequests; i++)
        scanf("%d", &requests[i]);
    
    printf("Enter initial head position: ");
    scanf("%d", &initialHead);
    
    for (i = 0; i < numRequests; i++)
        for (j = 0; j < numRequests - i - 1; j++)
            if (requests[j] > requests[j + 1]) 
            {
                int temp = requests[j];
                requests[j] = requests[j + 1];
                requests[j + 1] = temp;
            }
    
    int index;
    for (i = 0; i < numRequests; i++) 
        if (initialHead < requests[i]) 
        {
            index = i;
            break;
        }
    
    printf("1.Move towards Right 2.Move towards Left Enter your choice: ");
    scanf("%d",&ch);
    if(ch==1)
    {
        printf("---SCAN Head Movements---\n");
        for (i = index; i < numRequests; i++) 
        {
            currentMovement = abs(requests[i] - initialHead);
            printf("From %d to %d: %d\n",initialHead,requests[i],currentMovement);
            totalHeadMovement += currentMovement;
            initialHead = requests[i];
        }
        currentMovement = abs(diskSize - requests[i - 1] - 1);
        printf("From %d to right end: %d\n",requests[i-1],currentMovement);
        totalHeadMovement += currentMovement;
        initialHead = diskSize-1;
        for (i = index-1; i >= 0; i--) 
        {
            currentMovement = abs(requests[i] - initialHead);
            printf("From %d to %d: %d\n",initialHead,requests[i],currentMovement);
            totalHeadMovement += currentMovement;
            initialHead = requests[i];
        }
        printf("Total head movement: %d\n", totalHeadMovement);
    }
    
    else if (ch==2)
    {
        printf("---SCAN Head Movements---\n");
        for (i = index-1; i >=0; i--) 
        {
            currentMovement = abs(requests[i] - initialHead);
            printf("From %d to %d: %d\n",initialHead,requests[i],currentMovement);
            totalHeadMovement += currentMovement;
            initialHead = requests[i];
        }
        currentMovement = abs(0 - requests[0]);
        printf("From %d to left end: %d\n",requests[0],currentMovement);
        totalHeadMovement += currentMovement;
        initialHead = 0;
        for (i = index; i < numRequests; i++) 
        {
            currentMovement = abs(requests[i] - initialHead);
            printf("From %d to %d: %d\n",initialHead,requests[i],currentMovement);
            totalHeadMovement += currentMovement;
            initialHead = requests[i];
        }
        printf("Total head movement: %d\n", totalHeadMovement);
    }
    else
        printf("Wrong Choice!");
}
void cscan()
{
    int requests[100], i, j, numRequests, totalHeadMovement = 0, initialHead, diskSize, currentMovement , ch;
    printf("Enter total disk size: ");
    scanf("%d", &diskSize);
    
    printf("Enter the number of Requests: ");
    scanf("%d", &numRequests);
    
    printf("Enter the Requests sequence: ");
    for (i = 0; i < numRequests; i++)
        scanf("%d", &requests[i]);
    
    printf("Enter initial head position: ");
    scanf("%d", &initialHead);
    
    for (i = 0; i < numRequests; i++)
        for (j = 0; j < numRequests - i - 1; j++)
            if (requests[j] > requests[j + 1]) 
            {
                int temp = requests[j];
                requests[j] = requests[j + 1];
                requests[j + 1] = temp;
            }
    
    int index;
    for (i = 0; i < numRequests; i++)
        if (initialHead < requests[i]) 
        {
            index = i;
            break;
        }
    
    printf("1.Move towards Right 2.Move towards Left Enter your choice: ");
    scanf("%d",&ch);
    
    if(ch==1)
    {
        printf("--- C-SCAN Head Movements---\n");
        for (i = index; i < numRequests; i++) 
        {
            currentMovement = abs(requests[i] - initialHead);
            printf("From %d to %d: %d\n",initialHead,requests[i],currentMovement);
            totalHeadMovement += currentMovement;
            initialHead = requests[i];
        }
        currentMovement = abs(diskSize - requests[i - 1] - 1);
        printf("From %d to right end: %d\n",requests[i-1],currentMovement);
        totalHeadMovement += currentMovement;
        printf("From right end to start: %d\n",abs(diskSize - 1));
        totalHeadMovement += abs(diskSize - 1);
        initialHead = 0;
        for (i = 0; i < index; i++) 
        {
            currentMovement = abs(requests[i] - initialHead);
            printf("From %d to %d: %d\n",initialHead,requests[i],currentMovement);
            totalHeadMovement += currentMovement;
            initialHead = requests[i];
        }
        printf("Total head movement: %d\n", totalHeadMovement);
    }
    
    else if(ch==2)
    {
        printf("--- C-SCAN Head Movements---\n");
        for (i = index-1; i >=0; i--) 
        {
            currentMovement = abs(requests[i] - initialHead);
            printf("From %d to %d: %d\n",initialHead,requests[i],currentMovement);
            totalHeadMovement += currentMovement;
            initialHead = requests[i];
        }
        currentMovement = abs(0 - requests[0]);
        printf("From %d to left end: %d\n",requests[0],currentMovement);
        totalHeadMovement += currentMovement;
        printf("From start to right end: %d\n",abs(diskSize - 1));
        totalHeadMovement += abs(diskSize - 1);
        initialHead = diskSize-1;
        for (i = numRequests-1; i >= index; i--) 
        {
            currentMovement = abs(requests[i] - initialHead);
            printf("From %d to %d: %d\n",initialHead,requests[i],currentMovement);
            totalHeadMovement += currentMovement;
            initialHead = requests[i];
        }
        printf("Total head movement: %d\n", totalHeadMovement);
    }
    
    else
        printf("Wrong Choice!");
}