CS3413/Assignment8/code/main.c

#include <stdio.h>
#include <stdlib.h>
#include "disk.h"

// Global tracking variables
DiskDirection currentDirection = UP;
int movement = 0;
double seekTime = 0;

// Array for storing the requests
DiskQueue *queue;

double timeToProcessRequest(int position, int destination) {
	//The time (a floating point number) required to process a request is computed by distance the head travels divided by 5
	//Plus additional 15 milliseconds penalty if the direction has to change (for FCFS)
	double time = 0;
	// Calculated this way so that positive means up and negative means down
	int distance = destination - position;
	DiskDirection direction = (distance > 0) ? UP : DOWN;
	time += abs(distance) / 5.0;
	if (direction != currentDirection) {
		time += 15;
		currentDirection = direction;
	}
	return time;
}

int diskMovement(int position, int destination) {
	int distance = destination - position;
	return abs(distance);
}

// Your simulated disk is of size 10000, numbered from 0 to 9999.

// In first come first the time the request comes in is irrelevant
void fcfs(int start) {
	int position = start;
	while (queue->size > 0) {
		DiskRequest *request = dequeue(queue);
		while (seekTime < request->time) { seekTime++; }
		seekTime += timeToProcessRequest(position, request->position);
		movement += diskMovement(position, request->position);
		position = request->position;
		free(request);
	}
}

void cscan(int start) {
	int position = start;

	while (queue->size > 0) {
		DiskRequest *request = findClosest(queue, position, seekTime);
		if (request == NULL) {
			seekTime++;
		} else {
			if (request->position < position) {
				// + 1 simulates the time it takes to move to the end of the disk (it is a circular disk)
				seekTime += timeToProcessRequest(position, 9999 + 1);
				movement += diskMovement(position, 9999 + 1);
				position = 0;
				// Rescan for closest, so we can efficiently handle requests
				request = findClosest(queue, position, seekTime);
			}
			seekTime += timeToProcessRequest(position, request->position);
			movement += diskMovement(position, request->position);
			position = request->position;
		}
		if (request != NULL) {
			delete(queue, *request);
		}
	}
}


int main(int argc, char **argv) {
	int position, time;
	char algorithm = argv[1][0];
	int start = 0;

	queue = createDiskQueue();
	while (EOF != (scanf("%i %i\n", &position, &time))) {
		enqueue(queue, time, position);
	}
	if (algorithm == 'F') {
		fcfs(start);
		printf("Movement:%i Time:%.1lf\n", movement, seekTime);
	} else if (algorithm == 'C') {
		cscan(start);
		// Stupid printf difference to pass tests, could call once after if statement
		printf("Movement: %i Time:%.1lf\n", movement, seekTime);
	}
	destroyDiskQueue(queue);

	return 0;
}