440 lines
14 KiB
C
440 lines
14 KiB
C
/*
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* Copyright (c) 2010, Swedish Institute of Computer Science.
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* All rights reserved.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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* 1. Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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* 2. Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in the
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* documentation and/or other materials provided with the distribution.
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* 3. Neither the name of the Institute nor the names of its contributors
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* may be used to endorse or promote products derived from this software
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* without specific prior written permission.
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*
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* THIS SOFTWARE IS PROVIDED BY THE INSTITUTE AND CONTRIBUTORS ``AS IS'' AND
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* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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* ARE DISCLAIMED. IN NO EVENT SHALL THE INSTITUTE OR CONTRIBUTORS BE LIABLE
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* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
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* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
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* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
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* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
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* SUCH DAMAGE.
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*
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* This file is part of the Contiki operating system.
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*
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*/
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/**
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* \file
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* A Carrier Sense Multiple Access (CSMA) MAC layer
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* \author
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* Adam Dunkels <adam@sics.se>
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*/
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#include "net/mac/csma.h"
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#include "net/packetbuf.h"
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#include "net/queuebuf.h"
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#include "sys/ctimer.h"
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#include "sys/clock.h"
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#include "lib/random.h"
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#include "net/netstack.h"
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#include "lib/list.h"
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#include "lib/memb.h"
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#include <string.h>
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#include <stdio.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 /* DEBUG */
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#define PRINTF(...)
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#endif /* DEBUG */
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#ifndef CSMA_MAX_BACKOFF_EXPONENT
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#ifdef CSMA_CONF_MAX_BACKOFF_EXPONENT
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#define CSMA_MAX_BACKOFF_EXPONENT CSMA_CONF_MAX_BACKOFF_EXPONENT
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#else
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#define CSMA_MAX_BACKOFF_EXPONENT 3
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#endif /* CSMA_CONF_MAX_BACKOFF_EXPONENT */
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#endif /* CSMA_MAX_BACKOFF_EXPONENT */
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#ifndef CSMA_MAX_MAC_TRANSMISSIONS
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#ifdef CSMA_CONF_MAX_MAC_TRANSMISSIONS
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#define CSMA_MAX_MAC_TRANSMISSIONS CSMA_CONF_MAX_MAC_TRANSMISSIONS
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#else
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#define CSMA_MAX_MAC_TRANSMISSIONS 3
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#endif /* CSMA_CONF_MAX_MAC_TRANSMISSIONS */
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#endif /* CSMA_MAX_MAC_TRANSMISSIONS */
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#if CSMA_MAX_MAC_TRANSMISSIONS < 1
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#error CSMA_CONF_MAX_MAC_TRANSMISSIONS must be at least 1.
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#error Change CSMA_CONF_MAX_MAC_TRANSMISSIONS in contiki-conf.h or in your Makefile.
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#endif /* CSMA_CONF_MAX_MAC_TRANSMISSIONS < 1 */
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/* Packet metadata */
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struct qbuf_metadata {
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mac_callback_t sent;
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void *cptr;
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uint8_t max_transmissions;
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};
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/* Every neighbor has its own packet queue */
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struct neighbor_queue {
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struct neighbor_queue *next;
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linkaddr_t addr;
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struct ctimer transmit_timer;
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uint8_t transmissions;
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uint8_t collisions, deferrals;
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LIST_STRUCT(queued_packet_list);
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};
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/* The maximum number of co-existing neighbor queues */
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#ifdef CSMA_CONF_MAX_NEIGHBOR_QUEUES
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#define CSMA_MAX_NEIGHBOR_QUEUES CSMA_CONF_MAX_NEIGHBOR_QUEUES
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#else
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#define CSMA_MAX_NEIGHBOR_QUEUES 2
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#endif /* CSMA_CONF_MAX_NEIGHBOR_QUEUES */
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#define MAX_QUEUED_PACKETS QUEUEBUF_NUM
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MEMB(neighbor_memb, struct neighbor_queue, CSMA_MAX_NEIGHBOR_QUEUES);
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MEMB(packet_memb, struct rdc_buf_list, MAX_QUEUED_PACKETS);
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MEMB(metadata_memb, struct qbuf_metadata, MAX_QUEUED_PACKETS);
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LIST(neighbor_list);
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static void packet_sent(void *ptr, int status, int num_transmissions);
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static void transmit_packet_list(void *ptr);
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/*---------------------------------------------------------------------------*/
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static struct neighbor_queue *
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neighbor_queue_from_addr(const linkaddr_t *addr)
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{
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struct neighbor_queue *n = list_head(neighbor_list);
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while(n != NULL) {
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if(linkaddr_cmp(&n->addr, addr)) {
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return n;
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}
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n = list_item_next(n);
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}
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return NULL;
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}
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/*---------------------------------------------------------------------------*/
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static clock_time_t
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default_timebase(void)
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{
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clock_time_t time;
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/* The retransmission time must be proportional to the channel
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check interval of the underlying radio duty cycling layer. */
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time = NETSTACK_RDC.channel_check_interval();
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/* If the radio duty cycle has no channel check interval (i.e., it
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does not turn the radio off), we make the retransmission time
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proportional to the configured MAC channel check rate. */
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if(time == 0) {
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time = CLOCK_SECOND / NETSTACK_RDC_CHANNEL_CHECK_RATE;
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}
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return time;
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}
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/*---------------------------------------------------------------------------*/
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static void
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transmit_packet_list(void *ptr)
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{
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struct neighbor_queue *n = ptr;
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if(n) {
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struct rdc_buf_list *q = list_head(n->queued_packet_list);
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if(q != NULL) {
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PRINTF("csma: preparing number %d %p, queue len %d\n", n->transmissions, q,
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list_length(n->queued_packet_list));
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/* Send packets in the neighbor's list */
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NETSTACK_RDC.send_list(packet_sent, n, q);
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}
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}
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}
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/*---------------------------------------------------------------------------*/
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static void
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free_packet(struct neighbor_queue *n, struct rdc_buf_list *p)
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{
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if(p != NULL) {
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/* Remove packet from list and deallocate */
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list_remove(n->queued_packet_list, p);
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queuebuf_free(p->buf);
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memb_free(&metadata_memb, p->ptr);
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memb_free(&packet_memb, p);
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PRINTF("csma: free_queued_packet, queue length %d\n",
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list_length(n->queued_packet_list));
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if(list_head(n->queued_packet_list) != NULL) {
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/* There is a next packet. We reset current tx information */
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n->transmissions = 0;
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n->collisions = 0;
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n->deferrals = 0;
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/* Set a timer for next transmissions */
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ctimer_set(&n->transmit_timer, default_timebase(),
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transmit_packet_list, n);
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} else {
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/* This was the last packet in the queue, we free the neighbor */
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ctimer_stop(&n->transmit_timer);
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list_remove(neighbor_list, n);
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memb_free(&neighbor_memb, n);
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}
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}
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}
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/*---------------------------------------------------------------------------*/
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static void
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packet_sent(void *ptr, int status, int num_transmissions)
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{
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struct neighbor_queue *n;
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struct rdc_buf_list *q;
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struct qbuf_metadata *metadata;
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clock_time_t time = 0;
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mac_callback_t sent;
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void *cptr;
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int num_tx;
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int backoff_exponent;
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int backoff_transmissions;
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n = ptr;
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if(n == NULL) {
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return;
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}
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switch(status) {
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case MAC_TX_OK:
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case MAC_TX_NOACK:
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n->transmissions++;
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break;
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case MAC_TX_COLLISION:
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n->collisions++;
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break;
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case MAC_TX_DEFERRED:
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n->deferrals++;
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break;
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}
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for(q = list_head(n->queued_packet_list);
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q != NULL; q = list_item_next(q)) {
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if(queuebuf_attr(q->buf, PACKETBUF_ATTR_MAC_SEQNO) ==
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packetbuf_attr(PACKETBUF_ATTR_MAC_SEQNO)) {
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break;
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}
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}
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if(q != NULL) {
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metadata = (struct qbuf_metadata *)q->ptr;
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if(metadata != NULL) {
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sent = metadata->sent;
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cptr = metadata->cptr;
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num_tx = n->transmissions;
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if(status == MAC_TX_COLLISION ||
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status == MAC_TX_NOACK) {
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/* If the transmission was not performed because of a
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collision or noack, we must retransmit the packet. */
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switch(status) {
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case MAC_TX_COLLISION:
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PRINTF("csma: rexmit collision %d\n", n->transmissions);
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break;
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case MAC_TX_NOACK:
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PRINTF("csma: rexmit noack %d\n", n->transmissions);
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break;
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default:
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PRINTF("csma: rexmit err %d, %d\n", status, n->transmissions);
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}
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/* The retransmission time must be proportional to the channel
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check interval of the underlying radio duty cycling layer. */
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time = default_timebase();
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/* The retransmission time uses a truncated exponential backoff
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* so that the interval between the transmissions increase with
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* each retransmit. */
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backoff_exponent = num_tx;
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/* Truncate the exponent if needed. */
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if(backoff_exponent > CSMA_MAX_BACKOFF_EXPONENT) {
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backoff_exponent = CSMA_MAX_BACKOFF_EXPONENT;
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}
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/* Proceed to exponentiation. */
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backoff_transmissions = 1 << backoff_exponent;
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/* Pick a time for next transmission, within the interval:
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* [time, time + 2^backoff_exponent * time[ */
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time = time + (random_rand() % (backoff_transmissions * time));
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if(n->transmissions < metadata->max_transmissions) {
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PRINTF("csma: retransmitting with time %lu %p\n", time, q);
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ctimer_set(&n->transmit_timer, time,
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transmit_packet_list, n);
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/* This is needed to correctly attribute energy that we spent
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transmitting this packet. */
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queuebuf_update_attr_from_packetbuf(q->buf);
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} else {
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PRINTF("csma: drop with status %d after %d transmissions, %d collisions\n",
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status, n->transmissions, n->collisions);
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free_packet(n, q);
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mac_call_sent_callback(sent, cptr, status, num_tx);
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}
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} else {
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if(status == MAC_TX_OK) {
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PRINTF("csma: rexmit ok %d\n", n->transmissions);
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} else {
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PRINTF("csma: rexmit failed %d: %d\n", n->transmissions, status);
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}
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free_packet(n, q);
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mac_call_sent_callback(sent, cptr, status, num_tx);
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}
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}
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}
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}
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/*---------------------------------------------------------------------------*/
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static void
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send_packet(mac_callback_t sent, void *ptr)
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{
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struct rdc_buf_list *q;
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struct neighbor_queue *n;
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static uint8_t initialized = 0;
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static uint16_t seqno;
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const linkaddr_t *addr = packetbuf_addr(PACKETBUF_ADDR_RECEIVER);
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if(!initialized) {
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initialized = 1;
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/* Initialize the sequence number to a random value as per 802.15.4. */
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seqno = random_rand();
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}
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if(seqno == 0) {
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/* PACKETBUF_ATTR_MAC_SEQNO cannot be zero, due to a pecuilarity
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in framer-802154.c. */
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seqno++;
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}
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packetbuf_set_attr(PACKETBUF_ATTR_MAC_SEQNO, seqno++);
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/* Look for the neighbor entry */
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n = neighbor_queue_from_addr(addr);
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if(n == NULL) {
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/* Allocate a new neighbor entry */
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n = memb_alloc(&neighbor_memb);
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if(n != NULL) {
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/* Init neighbor entry */
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linkaddr_copy(&n->addr, addr);
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n->transmissions = 0;
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n->collisions = 0;
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n->deferrals = 0;
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/* Init packet list for this neighbor */
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LIST_STRUCT_INIT(n, queued_packet_list);
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/* Add neighbor to the list */
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list_add(neighbor_list, n);
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}
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}
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if(n != NULL) {
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/* Add packet to the neighbor's queue */
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q = memb_alloc(&packet_memb);
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if(q != NULL) {
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q->ptr = memb_alloc(&metadata_memb);
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if(q->ptr != NULL) {
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q->buf = queuebuf_new_from_packetbuf();
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if(q->buf != NULL) {
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struct qbuf_metadata *metadata = (struct qbuf_metadata *)q->ptr;
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/* Neighbor and packet successfully allocated */
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if(packetbuf_attr(PACKETBUF_ATTR_MAX_MAC_TRANSMISSIONS) == 0) {
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/* Use default configuration for max transmissions */
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metadata->max_transmissions = CSMA_MAX_MAC_TRANSMISSIONS;
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} else {
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metadata->max_transmissions =
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packetbuf_attr(PACKETBUF_ATTR_MAX_MAC_TRANSMISSIONS);
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}
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metadata->sent = sent;
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metadata->cptr = ptr;
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if(packetbuf_attr(PACKETBUF_ATTR_PACKET_TYPE) ==
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PACKETBUF_ATTR_PACKET_TYPE_ACK) {
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list_push(n->queued_packet_list, q);
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} else {
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list_add(n->queued_packet_list, q);
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}
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/* If q is the first packet in the neighbor's queue, send asap */
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if(list_head(n->queued_packet_list) == q) {
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ctimer_set(&n->transmit_timer, 0, transmit_packet_list, n);
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}
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return;
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}
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memb_free(&metadata_memb, q->ptr);
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PRINTF("csma: could not allocate queuebuf, dropping packet\n");
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}
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memb_free(&packet_memb, q);
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PRINTF("csma: could not allocate queuebuf, dropping packet\n");
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}
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/* The packet allocation failed. Remove and free neighbor entry if empty. */
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if(list_length(n->queued_packet_list) == 0) {
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list_remove(neighbor_list, n);
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memb_free(&neighbor_memb, n);
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}
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PRINTF("csma: could not allocate packet, dropping packet\n");
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} else {
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PRINTF("csma: could not allocate neighbor, dropping packet\n");
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}
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mac_call_sent_callback(sent, ptr, MAC_TX_ERR, 1);
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}
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/*---------------------------------------------------------------------------*/
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static void
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input_packet(void)
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{
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NETSTACK_NETWORK.input();
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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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return NETSTACK_RDC.on();
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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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return NETSTACK_RDC.off(keep_radio_on);
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}
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/*---------------------------------------------------------------------------*/
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static unsigned short
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channel_check_interval(void)
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{
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if(NETSTACK_RDC.channel_check_interval) {
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return NETSTACK_RDC.channel_check_interval();
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}
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return 0;
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}
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/*---------------------------------------------------------------------------*/
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static void
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init(void)
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{
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memb_init(&packet_memb);
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memb_init(&metadata_memb);
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memb_init(&neighbor_memb);
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}
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/*---------------------------------------------------------------------------*/
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const struct mac_driver csma_driver = {
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"CSMA",
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init,
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send_packet,
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input_packet,
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on,
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off,
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channel_check_interval,
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};
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/*---------------------------------------------------------------------------*/
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