/** * \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> * * $Id: etimer.c,v 1.3 2007/10/07 19:59:27 joxe Exp $ */ #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; } /*---------------------------------------------------------------------------*/ /** @} */