116 lines
4.4 KiB
C
116 lines
4.4 KiB
C
/*
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* Copyright (c) 2010, Swedish Institute of Computer Science.
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* All rights reserved.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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* 1. Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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* 2. Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in the
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* documentation and/or other materials provided with the distribution.
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* 3. Neither the name of the Institute nor the names of its contributors
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* may be used to endorse or promote products derived from this software
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* without specific prior written permission.
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*
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* THIS SOFTWARE IS PROVIDED BY THE INSTITUTE AND CONTRIBUTORS ``AS IS'' AND
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* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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* ARE DISCLAIMED. IN NO EVENT SHALL THE INSTITUTE OR CONTRIBUTORS BE LIABLE
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* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
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* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
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* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
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* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
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* SUCH DAMAGE.
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*
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* This file is part of the Contiki operating system.
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*
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* $Id: phase.c,v 1.1 2010/02/18 20:58:59 adamdunkels Exp $
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*/
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/**
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* \file
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* Common functionality for phase optimization in duty cycling radio protocols
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* \author
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* Adam Dunkels <adam@sics.se>
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*/
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#include "net/mac/phase.h"
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#include "net/rime/packetbuf.h"
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/*---------------------------------------------------------------------------*/
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void
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phase_register(const struct phase_list *list,
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const rimeaddr_t * neighbor, rtimer_clock_t time)
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{
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struct phase *e;
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/* If we have an entry for this neighbor already, we renew it. */
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for(e = list_head(*list->list); e != NULL; e = e->next) {
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if(rimeaddr_cmp(neighbor, &e->neighbor)) {
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e->time = time;
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break;
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}
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}
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/* No matching phase was found, so we allocate a new one. */
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if(e == NULL) {
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e = memb_alloc(list->memb);
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if(e == NULL) {
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/* We could not allocate memory for this phase, so we drop
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the last item on the list and reuse it for our phase. */
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e = list_chop(*list->list);
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}
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rimeaddr_copy(&e->neighbor, neighbor);
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e->time = time;
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list_push(*list->list, e);
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}
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}
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/*---------------------------------------------------------------------------*/
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void
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phase_wait(struct phase_list *list,
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const rimeaddr_t *neighbor, rtimer_clock_t cycle_time,
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rtimer_clock_t wait_before)
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{
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struct phase *e;
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/* We go through the list of phases to find if we have recorded
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an phase with this particular neighbor. If so, we can compute
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the time for the next expected phase and setup a ctimer to
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switch on the radio just before the phase. */
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for(e = list_head(*list->list); e != NULL; e = e->next) {
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const rimeaddr_t *neighbor = packetbuf_addr(PACKETBUF_ADDR_RECEIVER);
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if(rimeaddr_cmp(neighbor, &e->neighbor)) {
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rtimer_clock_t wait, now, expected;
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/* We expect phases to happen every CYCLE_TIME time
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units. The next expected phase is at time e->time +
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CYCLE_TIME. To compute a relative offset, we subtract
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with clock_time(). Because we are only interested in turning
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on the radio within the CYCLE_TIME period, we compute the
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waiting time with modulo CYCLE_TIME. */
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now = RTIMER_NOW();
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wait = (rtimer_clock_t)((e->time - now) & (cycle_time - 1));
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if(wait < wait_before) {
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wait += cycle_time;
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}
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expected = now + wait - wait_before;
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if(!RTIMER_CLOCK_LT(expected, now)) {
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/* Wait until the receiver is expected to be awake */
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while(RTIMER_CLOCK_LT(RTIMER_NOW(), expected));
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}
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}
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}
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}
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/*---------------------------------------------------------------------------*/
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void
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phase_init(struct phase_list *list)
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{
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list_init(*list->list);
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memb_init(list->memb);
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}
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/*---------------------------------------------------------------------------*/
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