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Added a simple CSMA (Carrier Sense Multiple Access) mechanism that
works on top of an underlying duty cycling mechanism. The CSMA layer retransmits packets that could not be sent because of a collision was detected.
This commit is contained in:
adamdunkels
parent
7ad93e5d18
commit
4f3e8d565c
@ -1,2 +1,2 @@
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CONTIKI_SOURCEFILES += xmac.c nullmac.c lpp.c frame802154.c sicslowmac.c
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CONTIKI_SOURCEFILES += framer.c framer-nullmac.c framer-802154.c
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CONTIKI_SOURCEFILES += framer.c framer-nullmac.c framer-802154.c csma.c
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206
core/net/mac/csma.c
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206
core/net/mac/csma.c
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/*
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* Copyright (c) 2007, 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 1.1 2010/01/25 11:46:44 adamdunkels Exp $
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*/
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/**
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* \file
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* A MAC
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* \author
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* Adam Dunkels <adam@sics.se>
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*/
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#define CSMA_CONF_REXMIT 1
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#include "net/mac/csma.h"
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#include "net/rime/packetbuf.h"
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#include "net/rime/queuebuf.h"
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#include "net/rime/ctimer.h"
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#include "lib/random.h"
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#include "lib/list.h"
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#include "lib/memb.h"
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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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uint8_t retransmits;
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};
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#define MAX_QUEUED_PACKETS 4
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LIST(packet_list);
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MEMB(packet_memb, struct queued_packet, MAX_QUEUED_PACKETS);
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static const struct mac_driver *mac;
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static void (* receiver_callback)(const struct mac_driver *);
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const struct mac_driver *csma_init(const struct mac_driver *psc);
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/*---------------------------------------------------------------------------*/
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#if CSMA_CONF_REXMIT
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static void
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retransmit_packet(void *ptr)
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{
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int ret;
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struct queued_packet *q = ptr;
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queuebuf_to_packetbuf(q->buf);
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ret = mac->send();
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queuebuf_free(q->buf);
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list_remove(packet_list, q);
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memb_free(&packet_memb, q);
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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 queuebuf *buf;
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int ret;
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clock_time_t time;
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rimeaddr_t receiver;
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/* Remember packet for later. */
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rimeaddr_copy(&receiver, packetbuf_addr(PACKETBUF_ADDR_RECEIVER));
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buf = queuebuf_new_from_packetbuf();
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ret = mac->send();
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/* if(ret != MAC_TX_OK) {
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printf("CSMA: err %d\n", ret);
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}*/
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/* Check if we saw a collission, and if we have a queuebuf with the
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packet available. Only retransmit unicast packets. Retransmit
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only once, for now. */
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if(ret == MAC_TX_COLLISION && buf != NULL &&
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!rimeaddr_cmp(&receiver, &rimeaddr_null)) {
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struct queued_packet *q;
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q = memb_alloc(&packet_memb);
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if(q == NULL) {
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queuebuf_free(buf);
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return ret;
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}
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q->buf = buf;
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q->retransmits = 0;
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time = mac->channel_check_interval();
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if(time == 0) {
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time = CLOCK_SECOND;
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}
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time = time + (random_rand() % (3 * time));
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ctimer_set(&q->retransmit_timer, time,
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retransmit_packet, q);
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list_add(packet_list, q);
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}
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queuebuf_free(buf);
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return ret;
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}
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#else /* CSMA_CONF_REXMIT */
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static int
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send_packet(void)
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{
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return mac->send();
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}
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#endif /* CSMA_CONF_REXMIT */
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/*---------------------------------------------------------------------------*/
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static void
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input_packet(const struct mac_driver *d)
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{
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if(receiver_callback) {
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receiver_callback(&csma_driver);
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}
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}
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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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len = mac->read();
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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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return mac->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 mac->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(mac->channel_check_interval) {
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return mac->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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#define NAMEBUF_LEN 16
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static char namebuf[NAMEBUF_LEN];
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const struct mac_driver csma_driver = {
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namebuf,
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csma_init,
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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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channel_check_interval,
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};
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/*---------------------------------------------------------------------------*/
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const struct mac_driver *
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csma_init(const struct mac_driver *psc)
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{
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memb_init(&packet_memb);
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list_init(packet_list);
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mac = psc;
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mac->set_receive_function(input_packet);
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/* printf("CSMA with MAC %s, channel check rate %d Hz\n", mac->name,
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CLOCK_SECOND / channel_check_interval());*/
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memcpy(namebuf, "CSMA ", 5);
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memcpy(namebuf + 5, psc->name, NAMEBUF_LEN - 6);
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return &csma_driver;
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}
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/*---------------------------------------------------------------------------*/
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52
core/net/mac/csma.h
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52
core/net/mac/csma.h
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@ -0,0 +1,52 @@
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/*
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* Copyright (c) 2007, 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.h,v 1.1 2010/01/25 11:46:44 adamdunkels Exp $
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*/
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/**
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* \file
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* A MAC stack protocol that performs retransmissions when the
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* underlying MAC layer has problems with collisions
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* \author
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* Adam Dunkels <adam@sics.se>
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*/
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#ifndef __CSMA_H__
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#define __CSMA_H__
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#include "net/mac/mac.h"
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#include "dev/radio.h"
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extern const struct mac_driver csma_driver;
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const struct mac_driver *csma_init(const struct mac_driver *r);
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#endif /* __CSMA_H__ */
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