316 lines
9.5 KiB
C
316 lines
9.5 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 1.2 2008/05/15 08:59:48 adamdunkels 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 "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/rimebuf.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 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 struct queuebuf *queued_packet;
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#define LISTEN_TIME CLOCK_SECOND / 64
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#define OFF_TIME CLOCK_SECOND / 2
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#define DUMP_QUEUED_PACKET 1
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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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/**
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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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rimebuf_clear();
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hdr = rimebuf_dataptr();
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rimebuf_set_datalen(sizeof(struct lpp_hdr));
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rimeaddr_copy(&hdr->sender, &rimeaddr_node_addr);
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rimeaddr_copy(&hdr->receiver, rimebuf_addr(RIMEBUF_ADDR_RECEIVER));
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hdr->type = TYPE_PROBE;
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PRINTF("Sending probe\n");
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radio->send(rimebuf_hdrptr(), rimebuf_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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if(queued_packet != NULL) {
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/* We are currently sending a packet so we should keep the radio
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turned on and not send any probes at this point. */
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ctimer_set(t, OFF_TIME * 2, dutycycle, t);
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PT_YIELD(&pt);
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queuebuf_free(queued_packet);
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queued_packet = NULL;
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PRINTF("Removing old packet\n");
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}
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turn_radio_on();
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send_probe();
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ctimer_set(t, LISTEN_TIME, dutycycle, t);
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PT_YIELD(&pt);
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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), dutycycle, t);
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PT_YIELD(&pt);
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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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rimebuf_hdralloc(sizeof(struct lpp_hdr));
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hdr = rimebuf_hdrptr();
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rimeaddr_copy(&hdr->sender, &rimeaddr_node_addr);
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rimeaddr_copy(&hdr->receiver, rimebuf_addr(RIMEBUF_ADDR_RECEIVER));
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hdr->type = TYPE_DATA;
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rimebuf_compact();
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PRINTF("queueing packet type %d\n", hdr->type);
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if(rimebuf_attr_isset(RIMEBUF_ATTR_PACKET_TYPE) &&
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rimebuf_attr(RIMEBUF_ATTR_PACKET_TYPE) == RIMEBUF_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(rimebuf_hdrptr(), rimebuf_totlen());
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} else {
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/* If a packet is already queued, the DUMP_QUEUED_PACKET option
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determines if the queued packet should be replaced with the new
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packet, or if the new packet should be dropped. XXX haven't
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measured the effect of this option */
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#if DUMP_QUEUED_PACKET
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if(queued_packet != NULL) {
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queuebuf_free(queued_packet);
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}
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queued_packet = queuebuf_new_from_rimebuf();
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#else /* DUMP_QUEUED_PACKET */
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if(queued_packet == NULL) {
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queued_packet = queuebuf_new_from_rimebuf();
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}
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#endif /* DUMP_QUEUED_PACKET */
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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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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, *qhdr;
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rimebuf_clear();
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len = radio->read(rimebuf_dataptr(), RIMEBUF_SIZE);
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if(len > 0) {
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rimebuf_set_datalen(len);
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hdr = rimebuf_dataptr();
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rimebuf_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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if(queued_packet != NULL) {
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qhdr = queuebuf_dataptr(queued_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\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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radio->send(queuebuf_dataptr(queued_packet),
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queuebuf_datalen(queued_packet));
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queuebuf_free(queued_packet);
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queued_packet = NULL;
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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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} 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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}
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len = rimebuf_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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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, dutycycle, &timer);
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return &lpp_driver;
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}
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/*---------------------------------------------------------------------------*/
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