contiki/core/sys/etimer.c

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/**
* \addtogroup etimer
* @{
*/
/**
* \file
* Event timer library implementation.
* \author
* Adam Dunkels <adam@sics.se>
*/
/*
* Copyright (c) 2004, Swedish Institute of Computer Science.
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
* 3. Neither the name of the Institute nor the names of its contributors
* may be used to endorse or promote products derived from this software
* without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE INSTITUTE AND CONTRIBUTORS ``AS IS'' AND
* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
* ARE DISCLAIMED. IN NO EVENT SHALL THE INSTITUTE OR CONTRIBUTORS BE LIABLE
* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
* SUCH DAMAGE.
*
* This file is part of the Contiki operating system.
*
* Author: Adam Dunkels <adam@sics.se>
*
*/
#include "contiki-conf.h"
#include "sys/etimer.h"
#include "sys/process.h"
static struct etimer *timerlist;
static clock_time_t next_expiration;
PROCESS(etimer_process, "Event timer");
/*---------------------------------------------------------------------------*/
static void
update_time(void)
{
clock_time_t tdist;
clock_time_t now;
struct etimer *t;
if (timerlist == NULL) {
next_expiration = 0;
} else {
now = clock_time();
t = timerlist;
/* Must calculate distance to next time into account due to wraps */
tdist = t->timer.start + t->timer.interval - now;
for(t = t->next; t != NULL; t = t->next) {
if(t->timer.start + t->timer.interval - now < tdist) {
tdist = t->timer.start + t->timer.interval - now;
}
}
next_expiration = now + tdist;
}
}
/*---------------------------------------------------------------------------*/
PROCESS_THREAD(etimer_process, ev, data)
{
struct etimer *t, *u;
PROCESS_BEGIN();
timerlist = NULL;
while(1) {
PROCESS_YIELD();
if(ev == PROCESS_EVENT_EXITED) {
struct process *p = data;
while(timerlist != NULL && timerlist->p == p) {
timerlist = timerlist->next;
}
if(timerlist != NULL) {
t = timerlist;
while(t->next != NULL) {
if(t->next->p == p) {
t->next = t->next->next;
} else
t = t->next;
}
}
continue;
} else if(ev != PROCESS_EVENT_POLL) {
continue;
}
again:
u = NULL;
for(t = timerlist; t != NULL; t = t->next) {
if(timer_expired(&t->timer)) {
if(process_post(t->p, PROCESS_EVENT_TIMER, t) == PROCESS_ERR_OK) {
/* Reset the process ID of the event timer, to signal that the
etimer has expired. This is later checked in the
etimer_expired() function. */
t->p = PROCESS_NONE;
if(u != NULL) {
u->next = t->next;
} else {
timerlist = t->next;
}
t->next = NULL;
update_time();
goto again;
} else {
etimer_request_poll();
}
}
u = t;
}
}
PROCESS_END();
}
/*---------------------------------------------------------------------------*/
void
etimer_request_poll(void)
{
process_poll(&etimer_process);
}
/*---------------------------------------------------------------------------*/
static void
add_timer(struct etimer *timer)
{
struct etimer *t;
etimer_request_poll();
if(timer->p != PROCESS_NONE) {
/* Timer not on list. */
for(t = timerlist; t != NULL; t = t->next) {
if(t == timer) {
/* Timer already on list, bail out. */
update_time();
return;
}
}
}
timer->p = PROCESS_CURRENT();
timer->next = timerlist;
timerlist = timer;
update_time();
}
/*---------------------------------------------------------------------------*/
void
etimer_set(struct etimer *et, clock_time_t interval)
{
timer_set(&et->timer, interval);
add_timer(et);
}
/*---------------------------------------------------------------------------*/
void
etimer_reset(struct etimer *et)
{
timer_reset(&et->timer);
add_timer(et);
}
/*---------------------------------------------------------------------------*/
void
etimer_restart(struct etimer *et)
{
timer_restart(&et->timer);
add_timer(et);
}
/*---------------------------------------------------------------------------*/
void
etimer_adjust(struct etimer *et, int timediff)
{
et->timer.start += timediff;
update_time();
}
/*---------------------------------------------------------------------------*/
int
etimer_expired(struct etimer *et)
{
return et->p == PROCESS_NONE;
}
/*---------------------------------------------------------------------------*/
clock_time_t
etimer_expiration_time(struct etimer *et)
{
return et->timer.start + et->timer.interval;
}
/*---------------------------------------------------------------------------*/
clock_time_t
etimer_start_time(struct etimer *et)
{
return et->timer.start;
}
/*---------------------------------------------------------------------------*/
int
etimer_pending(void)
{
return timerlist != NULL;
}
/*---------------------------------------------------------------------------*/
clock_time_t
etimer_next_expiration_time(void)
{
return etimer_pending() ? next_expiration : 0;
}
/*---------------------------------------------------------------------------*/
void
etimer_stop(struct etimer *et)
{
struct etimer *t;
/* First check if et is the first event timer on the list. */
if(et == timerlist) {
timerlist = timerlist->next;
update_time();
} else {
/* Else walk through the list and try to find the item before the
et timer. */
for(t = timerlist; t != NULL && t->next != et; t = t->next);
if(t != NULL) {
/* We've found the item before the event timer that we are about
to remove. We point the items next pointer to the event after
the removed item. */
t->next = et->next;
update_time();
}
}
/* Remove the next pointer from the item to be removed. */
et->next = NULL;
/* Set the timer as expired */
et->p = PROCESS_NONE;
}
/*---------------------------------------------------------------------------*/
/** @} */