/* nano_timer.c - timer for nanokernel-only systems */

/*
 * Copyright (c) 1997-2014 Wind River Systems, Inc.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

#include <nano_private.h>

struct nano_timer *_nano_timer_list;


void nano_timer_init(struct nano_timer *timer, void *data)
{
	nano_lifo_init(&timer->lifo);
	timer->userData = data;
	DEBUG_TRACING_OBJ_INIT(struct nano_timer *, timer, _track_list_nano_timer);
}


FUNC_ALIAS(_timer_start, nano_isr_timer_start, void);
FUNC_ALIAS(_timer_start, nano_fiber_timer_start, void);
FUNC_ALIAS(_timer_start, nano_task_timer_start, void);
FUNC_ALIAS(_timer_start, nano_timer_start, void);

/**
 *
 * @brief Start a nanokernel timer (generic implementation)
 *
 * This function starts a previously initialized nanokernel timer object.
 * The timer will expire in <ticks> system clock ticks.
 *
 * @param timer The Timer to start
 * @param ticks The number of system ticks before expiration
 *
 * @return N/A
 */
void _timer_start(struct nano_timer *timer, int ticks)
{
	unsigned int imask;
	struct nano_timer *cur;
	struct nano_timer *prev = NULL;

	timer->ticks = ticks;

	imask = irq_lock();

	cur = _nano_timer_list;

	while (cur && (timer->ticks > cur->ticks)) {
		timer->ticks -= cur->ticks;
		prev = cur;
		cur = cur->link;
	}

	timer->link = cur;
	if (cur != NULL)
		cur->ticks -= timer->ticks;

	if (prev != NULL)
		prev->link = timer;
	else
		_nano_timer_list = timer;

	irq_unlock(imask);
}

/**
 * @brief Stop a nanokernel timer (generic implementation)
 *
 * This function stops a previously started nanokernel timer object.
 * @param timer Timer to stop
 * @return N/A
 */
static void _timer_stop(struct nano_timer *timer)
{
	unsigned int imask;
	struct nano_timer *cur;
	struct nano_timer *prev = NULL;

	imask = irq_lock();

	cur = _nano_timer_list;

	/* find prev */
	while (cur && cur != timer) {
		prev = cur;
		cur = cur->link;
	}

	/* if found it, remove it */
	if (cur) {
		/* if it was first */
		if (prev == NULL) {
			_nano_timer_list = timer->link;
			/* if not last */
			if (_nano_timer_list)
				_nano_timer_list->ticks += timer->ticks;
		} else {
			prev->link = timer->link;
			/* if not last */
			if (prev->link)
				prev->link->ticks += timer->ticks;
		}
	}

	/* now the timer can't expire since it is removed from the list */

	irq_unlock(imask);
}


FUNC_ALIAS(_timer_stop_non_preemptible, nano_isr_timer_stop, void);
FUNC_ALIAS(_timer_stop_non_preemptible, nano_fiber_timer_stop, void);
void _timer_stop_non_preemptible(struct nano_timer *timer)
{
	extern void _lifo_put_non_preemptible(struct nano_lifo *lifo, void *data);

	_timer_stop(timer);

	/* if there was a waiter, kick it */
	if (timer->lifo.wait_q.head) {
		_lifo_put_non_preemptible(&timer->lifo, (void *)0);
	}
}

void nano_task_timer_stop(struct nano_timer *timer)
{

	_timer_stop(timer);

	/* if there was a waiter, kick it */
	if (timer->lifo.wait_q.head) {
		nano_task_lifo_put(&timer->lifo, (void *)0);
	}
}

void nano_timer_stop(struct nano_timer *timer)
{
	static void (*func[3])(struct nano_timer *) = {
		nano_isr_timer_stop,
		nano_fiber_timer_stop,
		nano_task_timer_stop,
	};

	func[sys_execution_context_type_get()](timer);
}