275 lines
8.2 KiB
C
275 lines
8.2 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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* $Id: csma.c,v 1.22 2010/10/24 21:07:00 adamdunkels Exp $
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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 "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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#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_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 1
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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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struct queued_packet {
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struct queued_packet *next;
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struct queuebuf *buf;
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struct ctimer retransmit_timer;
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mac_callback_t sent;
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void *cptr;
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uint8_t transmissions, max_transmissions;
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uint8_t collisions, deferrals;
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};
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#define MAX_QUEUED_PACKETS 8
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MEMB(packet_memb, struct queued_packet, MAX_QUEUED_PACKETS);
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static void packet_sent(void *ptr, int status, int num_transmissions);
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/*---------------------------------------------------------------------------*/
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static void
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retransmit_packet(void *ptr)
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{
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struct queued_packet *q = ptr;
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queuebuf_to_packetbuf(q->buf);
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PRINTF("csma: resending number %d %p\n", q->transmissions, q);
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NETSTACK_RDC.send(packet_sent, q);
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}
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/*---------------------------------------------------------------------------*/
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static void
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free_packet(struct queued_packet *q)
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{
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// printf("free_packet %p\n", q);
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ctimer_stop(&q->retransmit_timer);
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queuebuf_free(q->buf);
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memb_free(&packet_memb, q);
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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 queued_packet *q = ptr;
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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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// printf("packet_sent %p\n", q);
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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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q->transmissions++;
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break;
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case MAC_TX_COLLISION:
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q->collisions++;
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break;
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case MAC_TX_DEFERRED:
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q->deferrals++;
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break;
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}
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sent = q->sent;
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cptr = q->cptr;
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num_tx = q->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 collision or
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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", q->transmissions);
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break;
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case MAC_TX_NOACK:
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PRINTF("csma: rexmit noack %d\n", q->transmissions);
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break;
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default:
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PRINTF("csma: rexmit err %d, %d\n", status, q->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 = 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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/* The retransmission time uses a linear backoff so that the
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interval between the transmissions increase with each
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retransmit. */
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time = time + (random_rand() % ((q->transmissions + 1) * 2 * time));
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if(q->transmissions + q->collisions < q->max_transmissions) {
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PRINTF("csma: retransmitting with time %lu %p\n", time, q);
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ctimer_set(&q->retransmit_timer, time,
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retransmit_packet, q);
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} else {
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PRINTF("csma: drop after %d\n", q->transmissions);
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queuebuf_to_packetbuf(q->buf);
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free_packet(q);
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// printf("call 1 %p\n", cptr);
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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", q->transmissions);
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} else {
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PRINTF("csma: rexmit failed %d: %d\n", q->transmissions, status);
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}
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queuebuf_to_packetbuf(q->buf);
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free_packet(q);
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// printf("call 2 %p\n", cptr);
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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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static void
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send_packet(mac_callback_t sent, void *ptr)
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{
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struct queued_packet *q;
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static uint16_t seqno;
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packetbuf_set_attr(PACKETBUF_ATTR_MAC_SEQNO, seqno++);
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/* Remember packet for later. */
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q = memb_alloc(&packet_memb);
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if(q != NULL) {
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// printf("send_packet %p\n", q);
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q->buf = queuebuf_new_from_packetbuf();
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if(q != NULL) {
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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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q->max_transmissions = CSMA_MAX_MAC_TRANSMISSIONS;
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} else {
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q->max_transmissions =
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packetbuf_attr(PACKETBUF_ATTR_MAX_MAC_TRANSMISSIONS);
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}
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q->transmissions = 0;
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q->collisions = 0;
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q->deferrals = 0;
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q->sent = sent;
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q->cptr = ptr;
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NETSTACK_RDC.send(packet_sent, q);
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return;
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}
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memb_free(&packet_memb, q);
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}
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PRINTF("csma: could not allocate queuebuf, will drop if collision or noack\n");
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NETSTACK_RDC.send(sent, ptr);
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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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}
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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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