Respuesta :
Answer:
Explanation:
#include <stdio.h>
#include <stdlib.h>
#define CYLINDERS 5000
#define REQUESTS 1000
int initialHead = 0;
int disk[REQUESTS];
int* sortDisk()
{
 int temp = 0, m = 0, n = 0;
 //sort the disk using sorting algorithm
 for (m = 0; m < REQUESTS; ++m)
 {
   for (n = m + 1; n < REQUESTS; ++n)
   {
     if (disk[m] > disk[n])
     {
       temp = disk[m];
       disk[m] = disk[n];
       disk[n] = temp;
     }
   }
 }
 return disk;
}
int discSchedAlgFCFS(int *ran_array)
{
 int i = 0, headMovement = 0;
 int this_start = disk[initialHead];
 for (i = initialHead; i < REQUESTS; i++)
   //add absolute difference disk[i]
   //and this_start to head movement
   headMovement += abs(disk[i] - this_start);
 for (i = 0; i < initialHead; i++)
   headMovement += abs(this_start - ran_array[i]);
 //return head movments of fcfs
 return headMovement;
}
int discSchedAlgSSTF(int * disk)
{
 //befor start SSTF algorithm, first sort the disk
 disk = sortDisk();
 //Decalre the variables
 int s = initialHead - 1, l = initialHead + 1;
 int smallDiff = 0, largeDiff = 0;
 int headMovement = 0, n = REQUESTS - 2;
 int new_head = initialHead, head_value = disk[initialHead];
 //loop until the total number of request n to reach 0
 while (n >= 0)
 {
   //absolute difference disk[new_head]
   //and disk[s] into smallDiff
   smallDiff = abs(disk[new_head] - disk[s]);
   //absolute difference disk[new_head]
   //and disk[l] into largeDiff
   largeDiff = abs(disk[l] - disk[new_head]);
   //check if smallDiff is lessthan largeDiff
   if (smallDiff < largeDiff)
   {//then add smallDiff to headMovement
     headMovement += smallDiff;
     new_head = s;
     s--;//Decrement s
   }
   else
   {//else add largeDiff to headMovement
     headMovement += largeDiff;
     new_head = l;
     l++;//increament l
   }
   n--;
 }
 //return head movments of SSTF
 return headMovement;
}
int discSchedAlgSCAN(int * ranArray) {
 int i = 0, currentValue = 0;
 int savedValue = disk[initialHead], difference = 0;
 int headMovement = 0, curr_i = 0;
 for (i = initialHead - 1; i >= 0; --i)
 {
   currentValue = disk[i];
   //absolute difference value saved and current values
   difference = abs(savedValue - currentValue);
   //add difference to the head movment
   headMovement += difference;
   //save the current value as saved value
   savedValue = currentValue;
 }
 /* used to subtract value from zero, or just add same value */
 headMovement += savedValue;
 savedValue = 0;
 for (i = initialHead + 1; i < REQUESTS; i++)
 {
   currentValue = disk[i];
   //absolute difference value saved and current values
   difference = abs(currentValue - savedValue);
   //add difference to the head movment
   headMovement += difference;
   //save the current value as saved value
   savedValue = currentValue;
 }
 //return head movments of SCAN
 return headMovement;
}
int discSchedAlgCSCAN(int *disk) {
 int i = 0, currentValue = 0;
 int savedValue = disk[initialHead], diff = 0;
 int headMovement = 0, lastIndex = 4999;
 for (i = initialHead + 1; i < REQUESTS; i++)
 {
   currentValue = disk[i];
   //absolute difference value saved and current values
   diff = abs(savedValue - currentValue);
   //add difference to the head movment
   headMovement += diff;
   //save the current value as saved value
   savedValue = currentValue;
 }
 //add last val - upper bound, go to and
 //add zero bounday (4999)
 headMovement += lastIndex - savedValue;
 savedValue = 0;
 headMovement += 4999;
 for (i = 0; i < initialHead; i++)
 {
   currentValue = disk[i];
   //absolute difference value saved and current values
   diff = abs(currentValue - savedValue);
   //add difference to the head movment
   headMovement += diff;
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   savedValue = currentValue;
 }
 return headMovement;
}
int discSchedAlgLOOK(int* ranArray)
{
 int i = 0, currentValue = 0;
 int savedValue = disk[initialHead], diff = 0;
 int headMovement = 0, curr_i = 0;
 for (i = initialHead + 1; i < REQUESTS; i++)
 {
   currentValue = disk[i];
   //absolute difference value saved and current values
   diff = abs(savedValue - currentValue);
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   headMovement += diff;
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   savedValue = currentValue;
 }
 for (i = initialHead - 1; i >= 0; --i)
 {
   currentValue = disk[i];
   //absolute difference value saved and current values
   diff = abs(currentValue - savedValue);
   //add difference to the head movment
   headMovement += diff;
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   savedValue = currentValue;
 }
 //return head movments of LOOK
 return headMovement;
}
int discSchedAlgCLOOK(int* ranArray)
{
 int i = 0, currentValue = 0;
 int savedValue = disk[initialHead];
 int diff = 0;
 int headMovement = 0;
 for (i = initialHead + 1; i < REQUESTS; i++)
 {
   currentValue = disk[i];
   //absolute difference value saved and current values
   diff = abs(savedValue - currentValue);
   //add difference to the head movment
   headMovement += diff;
   //save the current value as saved value
   savedValue = currentValue;
 }
 for (i = 0; i < initialHead; i++)
 {
   currentValue = disk[i];
   //absolute difference value saved and current values
   diff = abs(currentValue - savedValue);
   //add difference to the head movment
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