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@ -57,10 +57,6 @@ void delete(DiskQueue *queue, DiskRequest request) {
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exit(EXIT_FAILURE);
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}
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DiskRequest peek(DiskQueue *queue) {
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return *queue->head;
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}
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DiskRequest *dequeue(DiskQueue *queue) {
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DiskRequest *head = queue->head;
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queue->head = head->next;
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@ -81,26 +77,34 @@ void destroyDiskQueue(DiskQueue *queue) {
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DiskRequest* findClosest(DiskQueue *queue, int position, double time) {
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DiskRequest *current = queue->head;
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DiskRequest *closest = NULL;
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DiskRequest *next = NULL;
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DiskRequest *first = NULL;
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while (current != NULL) {
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if (current->time <= time) { // Filter out requests that haven't come in yet
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if (closest == NULL) { // If there is no closest yet, set it to the current
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closest = current;
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if (first == NULL) {
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first = current;
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} else {
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int closestDistance = closest->position - position; // Distance from the closest to the current position, negative means down (bad)
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if (current->position < first->position) {
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first = current;
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}
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}
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int currentDistance = current->position - position; // Distance from the current to the current position, negative means down (bad)
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if (currentDistance > 0) { // If the current is up
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if (currentDistance < closestDistance) { // If the current is closer than the closest
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closest = current;
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if (next == NULL) { // If there is no next yet, set it to the current
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next = current;
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} else {
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int nextDistance = next->position - position; // Distance from the next to the current position, negative means down (bad)
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if (currentDistance < nextDistance) { // If the current is closer than the next
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next = current;
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}
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}
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}
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}
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current = current->next;
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}
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// Bad
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if (closest == NULL) {
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return NULL;
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// If we didn't find a request that is above the current position, return the first as a fallback
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if (next == NULL) {
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return first;
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}
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return closest;
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return next;
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}
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