#include <stdio.h>

#define NUM_GROUPS	3
#define NUM_TASKS	6

struct task_struct
{
	int pid;
	int gid;
	int time_slice;
	struct task_struct *next;
};

struct group_struct
{
	int num_tasks;
	struct task_struct *head;
	struct task_struct *tail;
};

struct task_struct task[NUM_TASKS];	// task array
struct group_struct group[NUM_GROUPS];	// group queues
int next_group = 0;			// next group to be scheduled

/* add a new task at the tail of the group queue */
void enqueue(struct task_struct *p)
{
	// add your own code here
}

/* remove the task pointed by p from its group queue */
/* Note: p may not be the head of queue in sched_exit()! */
void dequeue(struct task_struct *p)
{
	// add your own code here
}

/* move the task from the head to the tail of the group queue */
void requeue(struct task_struct *p)
{
	// add your own code here
}

void print_stat(int round)
{
	int i, j;
	struct task_struct *p;
 
	if (round)
		printf("\n\n");
	printf("************Round %d************\n", round);
	printf("GROUP_ID  TASK_ID  TIME_LEFT\n");
	for (i = 0; i < NUM_GROUPS; i++)
	{
		p = group[i].head;
		if (i && group[i].num_tasks)
			printf("-------------------------------\n");
		for (j = 0; j < group[i].num_tasks; j++)
		{
			printf("%8d  %7d  %9d\n", p->gid, p->pid, p->time_slice);
			p = p->next;
		}
	}
}

/* return 1 if all group queues are empty */
int empty()
{
	int i;

	for (i = 0; i < NUM_GROUPS; i++)
	{
		if (group[i].num_tasks)
			return 0;
	}

	return 1;
}

int main()
{
	int run_time[NUM_TASKS] = {250, 100, 100, 260, 200, 180};
	int group_id[NUM_TASKS] = {1024, 1024, 1024, 1025, 1026, 1026};
	int i, round;
	struct task_struct *next_task;

	/* Initialize our group queues */
	for (i = 0; i < NUM_GROUPS; i++)
	{
		group[i].num_tasks = 0;
		group[i].head = group[i].tail = NULL;
	}

	/* Initialize all the tasks and enqueue to different groups */
	for (i = 0; i < NUM_TASKS; i++)
	{
		task[i].pid = i;
		task[i].gid = group_id[i];
		task[i].time_slice = run_time[i];
		task[i].next = NULL;
		enqueue(&task[i]);
	}

	/* Group-based Fair Share Scheduling */
	round = 0;
	while (!empty())
	{
		/* print scheduling information */
		if (round % NUM_GROUPS == 0)
		{
			print_stat(round / NUM_GROUPS);
			printf("Tasks to run: ");
		}
		round++;

		/* if group queue is empty, skip it */
		if (group[next_group].num_tasks)
		{

			/* choose the next runnable task (head of the next_group) */
			next_task = group[next_group].head;
			printf("%d ", next_task->pid);
			next_task->time_slice -= 100;
			if (next_task->time_slice <= 0)
				dequeue(next_task);
			else
				requeue(next_task);
		}

		/* choose the next group queue to be scheduled */
		next_group = (next_group + 1) % NUM_GROUPS;
	}
	printf("\n");

	return 0;
}