678 lines
21 KiB
C
678 lines
21 KiB
C
/*
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* Copyright (c) 2008, 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: lpp.c,v 1.20 2009/04/07 11:29:08 nvt-se Exp $
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*/
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/**
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* \file
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* Low power probing (R. Musaloiu-Elefteri, C. Liang,
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* A. Terzis. Koala: Ultra-Low Power Data Retrieval in
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* Wireless Sensor Networks, IPSN 2008)
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*
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* \author
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* Adam Dunkels <adam@sics.se>
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*
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*
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* This is an implementation of the LPP (Low-Power Probing) MAC
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* protocol. LPP is a power-saving MAC protocol that works by sending
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* a probe packet each time the radio is turned on. If another node
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* wants to transmit a packet, it can do so after hearing the
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* probe. To send a packet, the sending node turns on its radio to
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* listen for probe packets.
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*
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*/
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#include "dev/leds.h"
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#include "lib/list.h"
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#include "lib/memb.h"
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#include "lib/random.h"
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#include "net/rime.h"
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#include "net/mac/mac.h"
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#include "net/mac/lpp.h"
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#include "net/rime/packetbuf.h"
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#include "net/rime/announcement.h"
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#include "sys/compower.h"
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#include <stdlib.h>
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#include <stdio.h>
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#include <string.h>
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#define DEBUG 0
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#if DEBUG
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#include <stdio.h>
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#define PRINTF(...) printf(__VA_ARGS__)
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#else
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#define PRINTF(...)
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#endif
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#define WITH_ACK_OPTIMIZATION 1
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#define WITH_PROBE_AFTER_RECEPTION 1
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#define WITH_PROBE_AFTER_TRANSMISSION 1
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struct announcement_data {
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uint16_t id;
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uint16_t value;
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};
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#define ANNOUNCEMENT_MSG_HEADERLEN 2
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struct announcement_msg {
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uint16_t num;
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struct announcement_data data[];
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};
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#define LPP_PROBE_HEADERLEN 2
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#define TYPE_PROBE 1
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#define TYPE_DATA 2
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struct lpp_hdr {
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uint16_t type;
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rimeaddr_t sender;
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rimeaddr_t receiver;
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};
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static struct compower_activity current_packet;
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static const struct radio_driver *radio;
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static void (* receiver_callback)(const struct mac_driver *);
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static struct pt dutycycle_pt;
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static struct ctimer timer;
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static uint8_t is_listening = 0;
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static clock_time_t off_time_adjustment = 0;
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#ifdef LPP_CONF_LISTEN_TIME
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#define LISTEN_TIME LPP_CONF_LISTEN_TIME
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#else
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#define LISTEN_TIME (CLOCK_SECOND / 64)
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#endif /** LP_CONF_LISTEN_TIME */
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#ifdef LPP_CONF_OFF_TIME
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#define OFF_TIME LPP_CONF_OFF_TIME
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#else
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#define OFF_TIME (CLOCK_SECOND / 4)
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#endif /* LPP_CONF_OFF_TIME */
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/* If CLOCK_SECOND is less than 4, we may end up with an OFF_TIME that
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is 0 which will make compilation fail due to a modulo operation in
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the code. To ensure that OFF_TIME is greater than zero, we use the
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construct below. */
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#if OFF_TIME == 0
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#undef OFF_TIME
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#define OFF_TIME 1
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#endif
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#define PACKET_LIFETIME (LISTEN_TIME + OFF_TIME)
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#define UNICAST_TIMEOUT (2 * PACKET_LIFETIME)
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#define PROBE_AFTER_TRANSMISSION_TIME (LISTEN_TIME * 2)
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#define ENCOUNTER_LIFETIME (16 * OFF_TIME)
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struct queue_list_item {
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struct queue_list_item *next;
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struct queuebuf *packet;
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struct ctimer timer;
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struct compower_activity compower;
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};
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#ifdef QUEUEBUF_CONF_NUM
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#define MAX_QUEUED_PACKETS QUEUEBUF_CONF_NUM / 2
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#else /* QUEUEBUF_CONF_NUM */
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#define MAX_QUEUED_PACKETS 4
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#endif /* QUEUEBUF_CONF_NUM */
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LIST(pending_packets_list);
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LIST(queued_packets_list);
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MEMB(queued_packets_memb, struct queue_list_item, MAX_QUEUED_PACKETS);
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struct encounter {
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struct encounter *next;
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rimeaddr_t neighbor;
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clock_time_t time;
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struct ctimer remove_timer;
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struct ctimer turn_on_radio_timer;
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};
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#define MAX_ENCOUNTERS 4
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LIST(encounter_list);
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MEMB(encounter_memb, struct encounter, MAX_ENCOUNTERS);
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/*---------------------------------------------------------------------------*/
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static void
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turn_radio_on(void)
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{
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radio->on();
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leds_on(LEDS_YELLOW);
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}
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/*---------------------------------------------------------------------------*/
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static void
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turn_radio_off(void)
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{
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radio->off();
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leds_off(LEDS_YELLOW);
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}
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/*---------------------------------------------------------------------------*/
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static void
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remove_encounter(void *encounter)
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{
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struct encounter *e = encounter;
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ctimer_stop(&e->remove_timer);
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ctimer_stop(&e->turn_on_radio_timer);
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list_remove(encounter_list, e);
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memb_free(&encounter_memb, e);
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}
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/*---------------------------------------------------------------------------*/
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static void
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register_encounter(rimeaddr_t *neighbor, clock_time_t time)
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{
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struct encounter *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(encounter_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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ctimer_set(&e->remove_timer, ENCOUNTER_LIFETIME, remove_encounter, e);
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break;
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}
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}
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/* No matchin encounter was found, so we allocate a new one. */
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if(e == NULL) {
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e = memb_alloc(&encounter_memb);
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if(e == NULL) {
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/* We could not allocate memory for this encounter, so we just drop it. */
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return;
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}
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rimeaddr_copy(&e->neighbor, neighbor);
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e->time = time;
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ctimer_set(&e->remove_timer, ENCOUNTER_LIFETIME, remove_encounter, e);
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list_add(encounter_list, e);
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}
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}
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/*---------------------------------------------------------------------------*/
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static void
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turn_radio_on_callback(void *packet)
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{
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struct queue_list_item *p = packet;
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list_remove(pending_packets_list, p);
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list_add(queued_packets_list, p);
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turn_radio_on();
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/* printf("enc\n");*/
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}
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/*---------------------------------------------------------------------------*/
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/* This function goes through all encounters to see if it finds a
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matching neighbor. If so, we set a ctimer that will turn on the
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radio just before we expect the neighbor to send a probe packet. If
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we cannot find a matching encounter, we just turn on the radio.
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The outbound packet is put on either the pending_packets_list or
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the queued_packets_list, depending on if the packet should be sent
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immediately.
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*/
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static void
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turn_radio_on_for_neighbor(rimeaddr_t *neighbor, struct queue_list_item *i)
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{
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struct encounter *e;
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if(rimeaddr_cmp(neighbor, &rimeaddr_null)) {
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/* We have been asked to turn on the radio for a broadcast, so we
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just turn on the radio. */
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turn_radio_on();
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list_add(queued_packets_list, i);
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return;
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}
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/* We go through the list of encounters to find if we have recorded
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an encounter with this particular neighbor. If so, we can compute
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the time for the next expected encounter and setup a ctimer to
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switch on the radio just before the encounter. */
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for(e = list_head(encounter_list); e != NULL; e = e->next) {
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if(rimeaddr_cmp(neighbor, &e->neighbor)) {
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clock_time_t wait, now;
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/* We expect encounters to happen roughly every OFF_TIME time
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units. The next expected encounter is at time e->time +
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OFF_TIME. To compute a relative offset, we subtract with
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clock_time(). Because we are only interested in turning on
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the radio within the OFF_TIME period, we compute the waiting
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time with modulo OFF_TIME. */
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now = clock_time();
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wait = ((clock_time_t)(e->time - now)) % (OFF_TIME);
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/* printf("now %d e %d e-n %d w %d %d\n", now, e->time, e->time - now, (e->time - now) % (OFF_TIME), wait);
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printf("Time now %lu last encounter %lu next expected encouter %lu wait %lu/%d (%lu)\n",
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(1000ul * (unsigned long)now) / CLOCK_SECOND,
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(1000ul * (unsigned long)e->time) / CLOCK_SECOND,
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(1000ul * (unsigned long)(e->time + OFF_TIME)) / CLOCK_SECOND,
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(1000ul * (unsigned long)wait) / CLOCK_SECOND, wait,
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(1000ul * (unsigned long)(wait + now)) / CLOCK_SECOND);*/
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/* printf("Neighbor %d.%d found encounter, waiting %d ticks\n",
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neighbor->u8[0], neighbor->u8[1], wait);*/
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ctimer_set(&e->turn_on_radio_timer, wait, turn_radio_on_callback, i);
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list_add(pending_packets_list, i);
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return;
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}
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}
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/* We did not find the neighbor in the list of recent encounters, so
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we just turn on the radio. */
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/* printf("Neighbor %d.%d not found in recent encounters\n",
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neighbor->u8[0], neighbor->u8[1]);*/
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turn_radio_on();
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list_add(queued_packets_list, i);
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return;
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}
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/*---------------------------------------------------------------------------*/
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static void
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remove_queued_packet(void *item)
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{
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struct queue_list_item *i = item;
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ctimer_stop(&i->timer);
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queuebuf_free(i->packet);
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list_remove(pending_packets_list, i);
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list_remove(queued_packets_list, i);
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/* XXX potential optimization */
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if(list_length(queued_packets_list) == 0 && is_listening == 0) {
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turn_radio_off();
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compower_accumulate(&i->compower);
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}
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memb_free(&queued_packets_memb, i);
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}
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/*---------------------------------------------------------------------------*/
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static void
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listen_callback(int periods)
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{
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is_listening = periods;
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turn_radio_on();
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}
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/*---------------------------------------------------------------------------*/
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/**
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* Send a probe packet.
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*/
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static void
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send_probe(void)
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{
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struct lpp_hdr *hdr;
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struct announcement_msg *adata;
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struct announcement *a;
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/* Set up the probe header. */
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packetbuf_clear();
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packetbuf_set_datalen(sizeof(struct lpp_hdr));
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hdr = packetbuf_dataptr();
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hdr->type = TYPE_PROBE;
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rimeaddr_copy(&hdr->sender, &rimeaddr_node_addr);
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rimeaddr_copy(&hdr->receiver, packetbuf_addr(PACKETBUF_ADDR_RECEIVER));
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/* Construct the announcements */
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adata = (struct announcement_msg *)((char *)hdr + sizeof(struct lpp_hdr));
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adata->num = 0;
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for(a = announcement_list(); a != NULL; a = a->next) {
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adata->data[adata->num].id = a->id;
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adata->data[adata->num].value = a->value;
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adata->num++;
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}
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packetbuf_set_datalen(sizeof(struct lpp_hdr) +
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ANNOUNCEMENT_MSG_HEADERLEN +
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sizeof(struct announcement_data) * adata->num);
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/* PRINTF("Sending probe\n");*/
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/* printf("probe\n");*/
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/* XXX should first check access to the medium (CCA - Clear Channel
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Assessment) and add LISTEN_TIME to off_time_adjustment if there
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is a packet in the air. */
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radio->send(packetbuf_hdrptr(), packetbuf_totlen());
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compower_accumulate(&compower_idle_activity);
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}
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/*---------------------------------------------------------------------------*/
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/**
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* Duty cycle the radio and send probes. This function is called
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* repeatedly by a ctimer. The function restart_dutycycle() is used to
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* (re)start the duty cycling.
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*/
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static int
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dutycycle(void *ptr)
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{
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struct ctimer *t = ptr;
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PT_BEGIN(&dutycycle_pt);
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while(1) {
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/* Send a probe packet. */
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send_probe();
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/* Turn on the radio for a while in anticipation of a data packet
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from a neighbor. */
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turn_radio_on();
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/* Set a timer so that we keep the radio on for LISTEN_TIME. */
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ctimer_set(t, LISTEN_TIME, (void (*)(void *))dutycycle, t);
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PT_YIELD(&dutycycle_pt);
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/* If we have no packets to send (indicated by the list length of
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queued_packets_list being zero), we should turn the radio
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off. Othersize, we keep the radio on. */
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if(list_length(queued_packets_list) == 0) {
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/* If we are not listening for announcements, we turn the radio
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off and wait until we send the next probe. */
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if(is_listening == 0) {
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turn_radio_off();
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compower_accumulate(&compower_idle_activity);
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ctimer_set(t, OFF_TIME + off_time_adjustment, (void (*)(void *))dutycycle, t);
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off_time_adjustment = 0;
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PT_YIELD(&dutycycle_pt);
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} else {
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is_listening--;
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ctimer_set(t, OFF_TIME, (void (*)(void *))dutycycle, t);
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PT_YIELD(&dutycycle_pt);
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}
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} else {
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ctimer_set(t, OFF_TIME, (void (*)(void *))dutycycle, t);
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PT_YIELD(&dutycycle_pt);
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}
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}
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PT_END(&dutycycle_pt);
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}
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/*---------------------------------------------------------------------------*/
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static void
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restart_dutycycle(clock_time_t initial_wait)
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{
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PT_INIT(&dutycycle_pt);
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ctimer_set(&timer, initial_wait, (void (*)(void *))dutycycle, &timer);
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}
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/*---------------------------------------------------------------------------*/
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/**
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*
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* Send a packet. This function builds a complete packet with an LPP
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* header and queues the packet. When a probe is heard (in the
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* read_packet() function), and the sender of the probe matches the
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* receiver of the queued packet, the queued packet is sent.
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*
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* ACK packets are treated differently from other packets: if a node
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* sends a packet that it expects to be ACKed, the sending node keeps
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* its radio on for some time after sending its packet. So we do not
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* need to wait for a probe packet: we just transmit the ACK packet
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* immediately.
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*
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*/
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static int
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send_packet(void)
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{
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struct lpp_hdr hdr;
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clock_time_t timeout;
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rimeaddr_copy(&hdr.sender, &rimeaddr_node_addr);
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rimeaddr_copy(&hdr.receiver, packetbuf_addr(PACKETBUF_ADDR_RECEIVER));
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hdr.type = TYPE_DATA;
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packetbuf_hdralloc(sizeof(struct lpp_hdr));
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memcpy(packetbuf_hdrptr(), &hdr, sizeof(struct lpp_hdr));
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packetbuf_compact();
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PRINTF("%d.%d: queueing packet to %d.%d, channel %d\n",
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rimeaddr_node_addr.u8[0], rimeaddr_node_addr.u8[1],
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hdr.receiver.u8[0], hdr.receiver.u8[1],
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packetbuf_attr(PACKETBUF_ATTR_CHANNEL));
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#if WITH_ACK_OPTIMIZATION
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if(packetbuf_attr(PACKETBUF_ATTR_PACKET_TYPE) == PACKETBUF_ATTR_PACKET_TYPE_ACK) {
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/* Send ACKs immediately. */
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radio->send(packetbuf_hdrptr(), packetbuf_totlen());
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return 1;
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}
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#endif /* WITH_ACK_OPTIMIZATION */
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{
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struct queue_list_item *i;
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i = memb_alloc(&queued_packets_memb);
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if(i != NULL) {
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i->packet = queuebuf_new_from_packetbuf();
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if(i->packet == NULL) {
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memb_free(&queued_packets_memb, i);
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return 0;
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} else {
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timeout = UNICAST_TIMEOUT;
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if(rimeaddr_cmp(&hdr.receiver, &rimeaddr_null)) {
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timeout = PACKET_LIFETIME;
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}
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ctimer_set(&i->timer, timeout, remove_queued_packet, i);
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/* Wait for a probe packet from a neighbor. The actual packet
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transmission is handled by the read_packet() function,
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which receives the probe from the neighbor. */
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turn_radio_on_for_neighbor(&hdr.receiver, i);
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}
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}
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}
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return 1;
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}
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/*---------------------------------------------------------------------------*/
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/**
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* Read a packet from the underlying radio driver. If the incoming
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* packet is a probe packet and the sender of the probe matches the
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* destination address of the queued packet (if any), the queued packet
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* is sent.
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*/
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static int
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read_packet(void)
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{
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int len;
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struct lpp_hdr *hdr;
|
|
clock_time_t reception_time;
|
|
|
|
reception_time = clock_time();
|
|
|
|
packetbuf_clear();
|
|
len = radio->read(packetbuf_dataptr(), PACKETBUF_SIZE);
|
|
if(len > sizeof(struct lpp_hdr)) {
|
|
packetbuf_set_datalen(len);
|
|
hdr = packetbuf_dataptr();
|
|
packetbuf_hdrreduce(sizeof(struct lpp_hdr));
|
|
/* PRINTF("got packet type %d\n", hdr->type);*/
|
|
if(hdr->type == TYPE_PROBE) {
|
|
/* Parse incoming announcements */
|
|
struct announcement_msg *adata = packetbuf_dataptr();
|
|
int i;
|
|
|
|
/* PRINTF("%d.%d: probe from %d.%d with %d announcements\n",
|
|
rimeaddr_node_addr.u8[0], rimeaddr_node_addr.u8[1],
|
|
hdr->sender.u8[0], hdr->sender.u8[1], adata->num);*/
|
|
|
|
for(i = 0; i < adata->num; ++i) {
|
|
/* PRINTF("%d.%d: announcement %d: %d\n",
|
|
rimeaddr_node_addr.u8[0], rimeaddr_node_addr.u8[1],
|
|
adata->data[i].id,
|
|
adata->data[i].value);*/
|
|
|
|
announcement_heard(&hdr->sender,
|
|
adata->data[i].id,
|
|
adata->data[i].value);
|
|
}
|
|
|
|
register_encounter(&hdr->sender, reception_time);
|
|
|
|
if(list_length(queued_packets_list) > 0) {
|
|
struct queue_list_item *i;
|
|
for(i = list_head(queued_packets_list); i != NULL; i = i->next) {
|
|
struct lpp_hdr *qhdr;
|
|
|
|
qhdr = queuebuf_dataptr(i->packet);
|
|
if(rimeaddr_cmp(&qhdr->receiver, &hdr->sender) ||
|
|
rimeaddr_cmp(&qhdr->receiver, &rimeaddr_null)) {
|
|
PRINTF("%d.%d: got a probe from %d.%d, sending packet to %d.%d\n",
|
|
rimeaddr_node_addr.u8[0], rimeaddr_node_addr.u8[1],
|
|
hdr->sender.u8[0], hdr->sender.u8[1],
|
|
qhdr->receiver.u8[0], qhdr->receiver.u8[1]);
|
|
queuebuf_to_packetbuf(i->packet);
|
|
|
|
radio->send(queuebuf_dataptr(i->packet),
|
|
queuebuf_datalen(i->packet));
|
|
|
|
/* Attribute the energy spent on listening for the probe
|
|
to this packet transmission. */
|
|
compower_accumulate(&i->compower);
|
|
|
|
/* If the packet was not a broadcast packet, we dequeue it
|
|
now. Broadcast packets should be transmitted to all
|
|
neighbors, and are dequeued by the dutycycling function
|
|
instead, after the appropriate time. */
|
|
if(!rimeaddr_cmp(&qhdr->receiver, &rimeaddr_null)) {
|
|
remove_queued_packet(i);
|
|
|
|
#if WITH_PROBE_AFTER_TRANSMISSION
|
|
/* Send a probe packet to catch any reply from the other node. */
|
|
restart_dutycycle(PROBE_AFTER_TRANSMISSION_TIME);
|
|
#endif /* WITH_PROBE_AFTER_TRANSMISSION */
|
|
}
|
|
|
|
#if WITH_ACK_OPTIMIZATION
|
|
if(packetbuf_attr(PACKETBUF_ATTR_RELIABLE)) {
|
|
/* We're sending a packet that needs an ACK, so we keep
|
|
the radio on in anticipation of the ACK. */
|
|
turn_radio_on();
|
|
}
|
|
#endif /* WITH_ACK_OPTIMIZATION */
|
|
|
|
}
|
|
}
|
|
}
|
|
|
|
} else if(hdr->type == TYPE_DATA) {
|
|
PRINTF("%d.%d: got data from %d.%d\n",
|
|
rimeaddr_node_addr.u8[0], rimeaddr_node_addr.u8[1],
|
|
hdr->sender.u8[0], hdr->sender.u8[1]);
|
|
|
|
/* Accumulate the power consumption for the packet reception. */
|
|
compower_accumulate(¤t_packet);
|
|
/* Convert the accumulated power consumption for the received
|
|
packet to packet attributes so that the higher levels can
|
|
keep track of the amount of energy spent on receiving the
|
|
packet. */
|
|
compower_attrconv(¤t_packet);
|
|
|
|
/* Clear the accumulated power consumption so that it is ready
|
|
for the next packet. */
|
|
compower_clear(¤t_packet);
|
|
|
|
#if WITH_PROBE_AFTER_RECEPTION
|
|
/* XXX send probe after receiving a packet to facilitate data
|
|
streaming. We must first copy the contents of the packetbuf into
|
|
a queuebuf to avoid overwriting the data with the probe packet. */
|
|
if(rimeaddr_cmp(&hdr->receiver, &rimeaddr_node_addr)) {
|
|
struct queuebuf *q;
|
|
q = queuebuf_new_from_packetbuf();
|
|
if(q != NULL) {
|
|
send_probe();
|
|
queuebuf_to_packetbuf(q);
|
|
queuebuf_free(q);
|
|
}
|
|
}
|
|
#endif /* WITH_PROBE_AFTER_RECEPTION */
|
|
}
|
|
|
|
len = packetbuf_datalen();
|
|
}
|
|
return len;
|
|
}
|
|
/*---------------------------------------------------------------------------*/
|
|
static void
|
|
set_receive_function(void (* recv)(const struct mac_driver *))
|
|
{
|
|
receiver_callback = recv;
|
|
}
|
|
/*---------------------------------------------------------------------------*/
|
|
static int
|
|
on(void)
|
|
{
|
|
turn_radio_on();
|
|
return 1;
|
|
}
|
|
/*---------------------------------------------------------------------------*/
|
|
static int
|
|
off(int keep_radio_on)
|
|
{
|
|
if(keep_radio_on) {
|
|
turn_radio_on();
|
|
} else {
|
|
turn_radio_off();
|
|
}
|
|
return 1;
|
|
}
|
|
/*---------------------------------------------------------------------------*/
|
|
static const struct mac_driver lpp_driver = {
|
|
"LPP",
|
|
send_packet,
|
|
read_packet,
|
|
set_receive_function,
|
|
on,
|
|
off,
|
|
};
|
|
/*---------------------------------------------------------------------------*/
|
|
static void
|
|
input_packet(const struct radio_driver *d)
|
|
{
|
|
if(receiver_callback) {
|
|
receiver_callback(&lpp_driver);
|
|
}
|
|
}
|
|
/*---------------------------------------------------------------------------*/
|
|
const struct mac_driver *
|
|
lpp_init(const struct radio_driver *d)
|
|
{
|
|
radio = d;
|
|
radio->set_receive_function(input_packet);
|
|
restart_dutycycle(random_rand() % OFF_TIME);
|
|
|
|
announcement_register_listen_callback(listen_callback);
|
|
|
|
memb_init(&queued_packets_memb);
|
|
list_init(queued_packets_list);
|
|
list_init(pending_packets_list);
|
|
return &lpp_driver;
|
|
}
|
|
/*---------------------------------------------------------------------------*/
|