osd-contiki/examples/rime/example-neighbors.c

/*
 * Copyright (c) 2010, Swedish Institute of Computer Science.
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 *    notice, this list of conditions and the following disclaimer.
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 *    notice, this list of conditions and the following disclaimer in the
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 *    may be used to endorse or promote products derived from this software
 *    without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE INSTITUTE AND CONTRIBUTORS ``AS IS'' AND
 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED.  IN NO EVENT SHALL THE INSTITUTE OR CONTRIBUTORS BE LIABLE
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 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
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 *
 * This file is part of the Contiki operating system.
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 */

/**
 * \file
 *         Demonstrates how to use broadcast and unicast
 * \author
 *         Adam Dunkels <adam@sics.se>
 *
 *         This example shows how to send broadcast and unicast, as
 *         well as how to use the Contiki memory block manager (MEMB)
 *         and the Contiki list library (LIST) to keep track of
 *         neighbors. The program consists of two processes, one that
 *         periodically sends broadcast messages and one that
 *         periodically sends unicast messages to random neighbors. A
 *         list of neighbors is maintained. The list is populated from
 *         the reception of broadcast messages from neighbors. The
 *         neighbor list keeps a simple set of quality metrics for
 *         each neighbor: a moving average of sequence number gaps,
 *         which indicates the number of broadcast packets that have
 *         been lost; a the last RSSI received; and the last LQI
 *         received.
 */


#include "contiki.h"
#include "lib/list.h"
#include "lib/memb.h"
#include "lib/random.h"
#include "net/rime/rime.h"

#include <stdio.h>

/* This is the structure of broadcast messages. */
struct broadcast_message {
  uint8_t seqno;
};

/* This is the structure of unicast ping messages. */
struct unicast_message {
  uint8_t type;
};

/* These are the types of unicast messages that we can send. */
enum {
  UNICAST_TYPE_PING,
  UNICAST_TYPE_PONG
};

/* This structure holds information about neighbors. */
struct neighbor {
  /* The ->next pointer is needed since we are placing these on a
     Contiki list. */
  struct neighbor *next;

  /* The ->addr field holds the Rime address of the neighbor. */
  linkaddr_t addr;

  /* The ->last_rssi and ->last_lqi fields hold the Received Signal
     Strength Indicator (RSSI) and CC2420 Link Quality Indicator (LQI)
     values that are received for the incoming broadcast packets. */
  uint16_t last_rssi, last_lqi;

  /* Each broadcast packet contains a sequence number (seqno). The
     ->last_seqno field holds the last sequenuce number we saw from
     this neighbor. */
  uint8_t last_seqno;

  /* The ->avg_gap contains the average seqno gap that we have seen
     from this neighbor. */
  uint32_t avg_seqno_gap;

};

/* This #define defines the maximum amount of neighbors we can remember. */
#define MAX_NEIGHBORS 16

/* This MEMB() definition defines a memory pool from which we allocate
   neighbor entries. */
MEMB(neighbors_memb, struct neighbor, MAX_NEIGHBORS);

/* The neighbors_list is a Contiki list that holds the neighbors we
   have seen thus far. */
LIST(neighbors_list);

/* These hold the broadcast and unicast structures, respectively. */
static struct broadcast_conn broadcast;
static struct unicast_conn unicast;

/* These two defines are used for computing the moving average for the
   broadcast sequence number gaps. */
#define SEQNO_EWMA_UNITY 0x100
#define SEQNO_EWMA_ALPHA 0x040

/*---------------------------------------------------------------------------*/
/* We first declare our two processes. */
PROCESS(broadcast_process, "Broadcast process");
PROCESS(unicast_process, "Unicast process");

/* The AUTOSTART_PROCESSES() definition specifices what processes to
   start when this module is loaded. We put both our processes
   there. */
AUTOSTART_PROCESSES(&broadcast_process, &unicast_process);
/*---------------------------------------------------------------------------*/
/* This function is called whenever a broadcast message is received. */
static void
broadcast_recv(struct broadcast_conn *c, const linkaddr_t *from)
{
  struct neighbor *n;
  struct broadcast_message *m;
  uint8_t seqno_gap;

  /* The packetbuf_dataptr() returns a pointer to the first data byte
     in the received packet. */
  m = packetbuf_dataptr();

  /* Check if we already know this neighbor. */
  for(n = list_head(neighbors_list); n != NULL; n = list_item_next(n)) {

    /* We break out of the loop if the address of the neighbor matches
       the address of the neighbor from which we received this
       broadcast message. */
    if(linkaddr_cmp(&n->addr, from)) {
      break;
    }
  }

  /* If n is NULL, this neighbor was not found in our list, and we
     allocate a new struct neighbor from the neighbors_memb memory
     pool. */
  if(n == NULL) {
    n = memb_alloc(&neighbors_memb);

    /* If we could not allocate a new neighbor entry, we give up. We
       could have reused an old neighbor entry, but we do not do this
       for now. */
    if(n == NULL) {
      return;
    }

    /* Initialize the fields. */
    linkaddr_copy(&n->addr, from);
    n->last_seqno = m->seqno - 1;
    n->avg_seqno_gap = SEQNO_EWMA_UNITY;

    /* Place the neighbor on the neighbor list. */
    list_add(neighbors_list, n);
  }

  /* We can now fill in the fields in our neighbor entry. */
  n->last_rssi = packetbuf_attr(PACKETBUF_ATTR_RSSI);
  n->last_lqi = packetbuf_attr(PACKETBUF_ATTR_LINK_QUALITY);

  /* Compute the average sequence number gap we have seen from this neighbor. */
  seqno_gap = m->seqno - n->last_seqno;
  n->avg_seqno_gap = (((uint32_t)seqno_gap * SEQNO_EWMA_UNITY) *
                      SEQNO_EWMA_ALPHA) / SEQNO_EWMA_UNITY +
                      ((uint32_t)n->avg_seqno_gap * (SEQNO_EWMA_UNITY -
                                                     SEQNO_EWMA_ALPHA)) /
    SEQNO_EWMA_UNITY;

  /* Remember last seqno we heard. */
  n->last_seqno = m->seqno;

  /* Print out a message. */
  printf("broadcast message received from %d.%d with seqno %d, RSSI %u, LQI %u, avg seqno gap %d.%02d\n",
         from->u8[0], from->u8[1],
         m->seqno,
         packetbuf_attr(PACKETBUF_ATTR_RSSI),
         packetbuf_attr(PACKETBUF_ATTR_LINK_QUALITY),
         (int)(n->avg_seqno_gap / SEQNO_EWMA_UNITY),
         (int)(((100UL * n->avg_seqno_gap) / SEQNO_EWMA_UNITY) % 100));
}
/* This is where we define what function to be called when a broadcast
   is received. We pass a pointer to this structure in the
   broadcast_open() call below. */
static const struct broadcast_callbacks broadcast_call = {broadcast_recv};
/*---------------------------------------------------------------------------*/
/* This function is called for every incoming unicast packet. */
static void
recv_uc(struct unicast_conn *c, const linkaddr_t *from)
{
  struct unicast_message *msg;

  /* Grab the pointer to the incoming data. */
  msg = packetbuf_dataptr();

  /* We have two message types, UNICAST_TYPE_PING and
     UNICAST_TYPE_PONG. If we receive a UNICAST_TYPE_PING message, we
     print out a message and return a UNICAST_TYPE_PONG. */
  if(msg->type == UNICAST_TYPE_PING) {
    printf("unicast ping received from %d.%d\n",
           from->u8[0], from->u8[1]);
    msg->type = UNICAST_TYPE_PONG;
    packetbuf_copyfrom(msg, sizeof(struct unicast_message));
    /* Send it back to where it came from. */
    unicast_send(c, from);
  }
}
static const struct unicast_callbacks unicast_callbacks = {recv_uc};
/*---------------------------------------------------------------------------*/
PROCESS_THREAD(broadcast_process, ev, data)
{
  static struct etimer et;
  static uint8_t seqno;
  struct broadcast_message msg;

  PROCESS_EXITHANDLER(broadcast_close(&broadcast);)

  PROCESS_BEGIN();

  broadcast_open(&broadcast, 129, &broadcast_call);

  while(1) {

    /* Send a broadcast every 16 - 32 seconds */
    etimer_set(&et, CLOCK_SECOND * 16 + random_rand() % (CLOCK_SECOND * 16));

    PROCESS_WAIT_EVENT_UNTIL(etimer_expired(&et));

    msg.seqno = seqno;
    packetbuf_copyfrom(&msg, sizeof(struct broadcast_message));
    broadcast_send(&broadcast);
    seqno++;
  }

  PROCESS_END();
}
/*---------------------------------------------------------------------------*/
PROCESS_THREAD(unicast_process, ev, data)
{
  PROCESS_EXITHANDLER(unicast_close(&unicast);)
    
  PROCESS_BEGIN();

  unicast_open(&unicast, 146, &unicast_callbacks);

  while(1) {
    static struct etimer et;
    struct unicast_message msg;
    struct neighbor *n;
    int randneighbor, i;
    
    etimer_set(&et, CLOCK_SECOND * 8 + random_rand() % (CLOCK_SECOND * 8));
    
    PROCESS_WAIT_EVENT_UNTIL(etimer_expired(&et));

    /* Pick a random neighbor from our list and send a unicast message to it. */
    if(list_length(neighbors_list) > 0) {
      randneighbor = random_rand() % list_length(neighbors_list);
      n = list_head(neighbors_list);
      for(i = 0; i < randneighbor; i++) {
        n = list_item_next(n);
      }
      printf("sending unicast to %d.%d\n", n->addr.u8[0], n->addr.u8[1]);

      msg.type = UNICAST_TYPE_PING;
      packetbuf_copyfrom(&msg, sizeof(msg));
      unicast_send(&unicast, &n->addr);
    }
  }

  PROCESS_END();
}
/*---------------------------------------------------------------------------*/