448 lines
13 KiB
C
448 lines
13 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 1.14 2009/03/31 14:44:13 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 <stdlib.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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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 const struct radio_driver *radio;
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static void (* receiver_callback)(const struct mac_driver *);
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static struct pt pt;
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static struct ctimer timer;
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static uint8_t is_listening = 0;
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#define LISTEN_TIME CLOCK_SECOND / 32
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#define OFF_TIME CLOCK_SECOND * 1
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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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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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};
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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(queued_packets_list);
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MEMB(queued_packets_memb, struct queue_list_item, MAX_QUEUED_PACKETS);
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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_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(queued_packets_list, i);
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memb_free(&queued_packets_memb, 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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}
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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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radio->send(packetbuf_hdrptr(), packetbuf_totlen());
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}
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/*---------------------------------------------------------------------------*/
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/**
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* Duty cycle the radio. The protothread is driven by a ctimer that is
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* initiated in the lpp_init() function.
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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(&pt);
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while(1) {
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turn_radio_on();
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send_probe();
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ctimer_set(t, LISTEN_TIME, (void (*)(void *))dutycycle, t);
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PT_YIELD(&pt);
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if(list_length(queued_packets_list) == 0) {
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if(is_listening == 0) {
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turn_radio_off();
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/* There is a bit of randomness here right now to avoid collisions
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due to synchronization effects. Not sure how needed it is
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though. XXX */
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ctimer_set(t, OFF_TIME / 2 + (random_rand() % (OFF_TIME / 2)),
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(void (*)(void *))dutycycle, t);
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PT_YIELD(&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(&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(&pt);
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}
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}
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PT_END(&pt);
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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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packetbuf_hdralloc(sizeof(struct lpp_hdr));
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hdr = packetbuf_hdrptr();
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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_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(packetbuf_attr(PACKETBUF_ATTR_PACKET_TYPE) == PACKETBUF_ATTR_PACKET_TYPE_ACK) {
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/* Immediately send ACKs - we're assuming that the other node is
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listening. */
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/* printf("Immediately sending ACK\n");*/
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return radio->send(packetbuf_hdrptr(), packetbuf_totlen());
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} else {
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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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list_add(queued_packets_list, i);
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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 */
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turn_radio_on();
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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;
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packetbuf_clear();
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len = radio->read(packetbuf_dataptr(), PACKETBUF_SIZE);
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if(len > 0) {
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packetbuf_set_datalen(len);
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hdr = packetbuf_dataptr();
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packetbuf_hdrreduce(sizeof(struct lpp_hdr));
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/* PRINTF("got packet type %d\n", hdr->type);*/
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if(hdr->type == TYPE_PROBE) {
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/* Parse incoming announcements */
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struct announcement_msg *adata = packetbuf_dataptr();
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int i;
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/* PRINTF("%d.%d: probe from %d.%d with %d announcements\n",
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rimeaddr_node_addr.u8[0], rimeaddr_node_addr.u8[1],
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hdr->sender.u8[0], hdr->sender.u8[1], adata->num);*/
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for(i = 0; i < adata->num; ++i) {
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/* PRINTF("%d.%d: announcement %d: %d\n",
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rimeaddr_node_addr.u8[0], rimeaddr_node_addr.u8[1],
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adata->data[i].id,
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adata->data[i].value);*/
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announcement_heard(&hdr->sender,
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adata->data[i].id,
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adata->data[i].value);
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}
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if(list_length(queued_packets_list) > 0) {
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struct queue_list_item *i;
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for(i = list_head(queued_packets_list); i != NULL; i = i->next) {
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struct lpp_hdr *qhdr;
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qhdr = queuebuf_dataptr(i->packet);
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if(rimeaddr_cmp(&qhdr->receiver, &hdr->sender) ||
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rimeaddr_cmp(&qhdr->receiver, &rimeaddr_null)) {
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PRINTF("%d.%d: got a probe from %d.%d, sending packet to %d.%d\n",
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rimeaddr_node_addr.u8[0], rimeaddr_node_addr.u8[1],
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hdr->sender.u8[0], hdr->sender.u8[1],
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qhdr->receiver.u8[0], qhdr->receiver.u8[1]);
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radio->send(queuebuf_dataptr(i->packet),
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queuebuf_datalen(i->packet));
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/* If the packet was not a broadcast packet, we dequeue it
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now. Broadcast packets should be transmitted to all
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neighbors, and are dequeued by the dutycycling function
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instead, after the appropriate time. */
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if(!rimeaddr_cmp(&qhdr->receiver, &rimeaddr_null)) {
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remove_queued_packet(i);
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}
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turn_radio_on(); /* XXX Awaiting an ACK: we should check the
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packet type of the queued packet to see
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if it is a data packet. If not, we
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should not turn the radio on. */
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}
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}
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}
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} else if(hdr->type == TYPE_DATA) {
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PRINTF("%d.%d: got data from %d.%d\n",
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rimeaddr_node_addr.u8[0], rimeaddr_node_addr.u8[1],
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hdr->sender.u8[0], hdr->sender.u8[1]);
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/* XXX send probe after receiving a packet to facilitate data
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streaming. We must first copy the contents of the packetbuf into
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a queuebuf to avoid overwriting the data with the probe packet. */
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if(rimeaddr_cmp(&hdr->receiver, &rimeaddr_node_addr)) {
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struct queuebuf *q;
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q = queuebuf_new_from_packetbuf();
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if(q != NULL) {
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send_probe();
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queuebuf_to_packetbuf(q);
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queuebuf_free(q);
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}
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}
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}
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len = packetbuf_datalen();
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}
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return len;
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}
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/*---------------------------------------------------------------------------*/
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static void
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set_receive_function(void (* recv)(const struct mac_driver *))
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{
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receiver_callback = recv;
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}
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/*---------------------------------------------------------------------------*/
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static int
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on(void)
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{
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turn_radio_on();
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return 1;
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}
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/*---------------------------------------------------------------------------*/
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static int
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off(int keep_radio_on)
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{
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if(keep_radio_on) {
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turn_radio_on();
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} else {
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turn_radio_off();
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}
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return 1;
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}
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/*---------------------------------------------------------------------------*/
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static const struct mac_driver lpp_driver = {
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"LPP",
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send_packet,
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read_packet,
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set_receive_function,
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on,
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off,
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};
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/*---------------------------------------------------------------------------*/
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static void
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input_packet(const struct radio_driver *d)
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{
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if(receiver_callback) {
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receiver_callback(&lpp_driver);
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}
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}
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/*---------------------------------------------------------------------------*/
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const struct mac_driver *
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lpp_init(const struct radio_driver *d)
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{
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radio = d;
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radio->set_receive_function(input_packet);
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ctimer_set(&timer, LISTEN_TIME, (void (*)(void *))dutycycle, &timer);
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announcement_register_listen_callback(listen_callback);
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memb_init(&queued_packets_memb);
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list_init(queued_packets_list);
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return &lpp_driver;
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}
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/*---------------------------------------------------------------------------*/
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