97 lines
2.7 KiB
C
97 lines
2.7 KiB
C
#include <stdio.h>
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#include <stdlib.h>
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#include "disk.h"
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// Global tracking variables
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DiskDirection currentDirection = UP;
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int movement = 0;
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double seekTime = 0;
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// Array for storing the requests
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DiskQueue *queue;
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double timeToProcessRequest(int position, int destination) {
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//The time (a floating point number) required to process a request is computed by distance the head travels divided by 5
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//Plus additional 15 milliseconds penalty if the direction has to change (for FCFS)
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double time = 0;
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// Calculated this way so that positive means up and negative means down
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int distance = destination - position;
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DiskDirection direction = (distance > 0) ? UP : DOWN;
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time += abs(distance) / 5.0;
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if (direction != currentDirection) {
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time += 15;
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currentDirection = direction;
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}
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return time;
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}
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int diskMovement(int position, int destination) {
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int distance = destination - position;
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return abs(distance);
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}
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// Your simulated disk is of size 10000, numbered from 0 to 9999.
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// In first come first the time the request comes in is irrelevant
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void fcfs(int start) {
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int position = start;
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while (queue->size > 0) {
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DiskRequest *request = dequeue(queue);
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while (seekTime < request->time) { seekTime++; }
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seekTime += timeToProcessRequest(position, request->position);
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movement += diskMovement(position, request->position);
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position = request->position;
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free(request);
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}
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}
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void cscan(int start) {
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int position = start;
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while (queue->size > 0) {
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DiskRequest *request = findClosest(queue, position, seekTime);
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if (request == NULL) {
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seekTime++;
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} else {
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if (request->position < position) {
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// + 1 simulates the time it takes to move to the end of the disk (it is a circular disk)
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seekTime += timeToProcessRequest(position, 9999 + 1);
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movement += diskMovement(position, 9999 + 1);
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position = 0;
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// Rescan for closest, so we can efficiently handle requests
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request = findClosest(queue, position, seekTime);
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}
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seekTime += timeToProcessRequest(position, request->position);
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movement += diskMovement(position, request->position);
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position = request->position;
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}
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if (request != NULL) {
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delete(queue, *request);
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}
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//printf("Movement: %i Time:%.1lf\n", movement, seekTime);
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}
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}
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int main(int argc, char **argv) {
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int position, time;
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char algorithm = argv[1][0];
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int start = 0;
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queue = createDiskQueue();
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while (EOF != (scanf("%i %i\n", &position, &time))) {
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enqueue(queue, time, position);
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}
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if (algorithm == 'F') {
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fcfs(start);
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printf("Movement:%i Time:%.1lf\n", movement, seekTime);
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} else if (algorithm == 'C') {
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cscan(start);
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// Stupid printf difference to pass tests, could call once after if statement
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printf("Movement: %i Time:%.1lf\n", movement, seekTime);
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}
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destroyDiskQueue(queue);
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return 0;
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}
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