osd-contiki/core/net/mac/csma.c
adamdunkels ae88ed04f1 Moved the definition of the channel check rate used by the radio duty
cycling layer. This definition was previously held in net/mac/mac.h,
with the name MAC_CONF_CHANNEL_CHECK_RATE. But since the rate is used
by the radio duty cycling layer, it makes more sense to change its
name to reflect this. Also, the configuration option should be tied to
the netstack configuration instead.

So the new configuration option is called
NETSTACK_CONF_RDC_CHANNEL_CHECK_RATE.
2010-10-03 20:37:32 +00:00

263 lines
7.9 KiB
C

/*
* Copyright (c) 2010, Swedish Institute of Computer Science.
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
* 3. Neither the name of the Institute nor the names of its contributors
* 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
* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
* SUCH DAMAGE.
*
* This file is part of the Contiki operating system.
*
* $Id: csma.c,v 1.20 2010/10/03 20:37:32 adamdunkels Exp $
*/
/**
* \file
* A Carrier Sense Multiple Access (CSMA) MAC layer
* \author
* Adam Dunkels <adam@sics.se>
*/
#include "net/mac/csma.h"
#include "net/packetbuf.h"
#include "net/queuebuf.h"
#include "sys/ctimer.h"
#include "lib/random.h"
#include "net/netstack.h"
#include "lib/list.h"
#include "lib/memb.h"
#include <string.h>
#define DEBUG 0
#if DEBUG
#include <stdio.h>
#define PRINTF(...) printf(__VA_ARGS__)
#else /* DEBUG */
#define PRINTF(...)
#endif /* DEBUG */
#ifndef CSMA_MAX_MAC_TRANSMISSIONS
#ifdef CSMA_CONF_MAX_MAC_TRANSMISSIONS
#define CSMA_MAX_MAC_TRANSMISSIONS CSMA_CONF_MAX_MAC_TRANSMISSIONS
#else
#define CSMA_MAX_MAC_TRANSMISSIONS 1
#endif /* CSMA_CONF_MAX_MAC_TRANSMISSIONS */
#endif /* CSMA_MAX_MAC_TRANSMISSIONS */
#if CSMA_MAX_MAC_TRANSMISSIONS < 1
#error CSMA_CONF_MAX_MAC_TRANSMISSIONS must be at least 1.
#error Change CSMA_CONF_MAX_MAC_TRANSMISSIONS in contiki-conf.h or in your Makefile.
#endif /* CSMA_CONF_MAX_MAC_TRANSMISSIONS < 1 */
struct queued_packet {
struct queued_packet *next;
struct queuebuf *buf;
struct ctimer retransmit_timer;
mac_callback_t sent;
void *cptr;
uint8_t transmissions, max_transmissions;
uint8_t collisions, deferrals;
};
#define MAX_QUEUED_PACKETS 8
MEMB(packet_memb, struct queued_packet, MAX_QUEUED_PACKETS);
static void packet_sent(void *ptr, int status, int num_transmissions);
/*---------------------------------------------------------------------------*/
static void
retransmit_packet(void *ptr)
{
struct queued_packet *q = ptr;
queuebuf_to_packetbuf(q->buf);
PRINTF("csma: resending number %d %p\n", q->transmissions, q);
NETSTACK_RDC.send(packet_sent, q);
}
/*---------------------------------------------------------------------------*/
static void
free_packet(struct queued_packet *q)
{
queuebuf_free(q->buf);
memb_free(&packet_memb, q);
ctimer_stop(&q->retransmit_timer);
}
/*---------------------------------------------------------------------------*/
static void
packet_sent(void *ptr, int status, int num_transmissions)
{
struct queued_packet *q = ptr;
clock_time_t time = 0;
mac_callback_t sent;
void *cptr;
int num_tx;
switch(status) {
case MAC_TX_OK:
case MAC_TX_NOACK:
q->transmissions++;
break;
case MAC_TX_COLLISION:
q->collisions++;
break;
case MAC_TX_DEFERRED:
q->deferrals++;
break;
}
sent = q->sent;
cptr = q->cptr;
num_tx = q->transmissions;
if(status == MAC_TX_COLLISION ||
status == MAC_TX_NOACK) {
/* If the transmission was not performed because of a collision or
noack, we must retransmit the packet. */
switch(status) {
case MAC_TX_COLLISION:
PRINTF("csma: rexmit collision %d\n", q->transmissions);
break;
case MAC_TX_NOACK:
PRINTF("csma: rexmit noack %d\n", q->transmissions);
break;
default:
PRINTF("csma: rexmit err %d, %d\n", status, q->transmissions);
}
/* The retransmission time must be proportional to the channel
check interval of the underlying radio duty cycling layer. */
time = NETSTACK_RDC.channel_check_interval();
/* If the radio duty cycle has no channel check interval (i.e., it
does not turn the radio off), we make the retransmission time
proportional to the configured MAC channel check rate. */
if(time == 0) {
time = CLOCK_SECOND / NETSTACK_RDC_CHANNEL_CHECK_RATE;
}
/* The retransmission time uses a linear backoff so that the
interval between the transmissions increase with each
retransmit. */
time = time + (random_rand() % ((q->transmissions + 1) * 3 * time));
if(q->transmissions + q->collisions < q->max_transmissions) {
PRINTF("csma: retransmitting with time %lu %p\n", time, q);
ctimer_set(&q->retransmit_timer, time,
retransmit_packet, q);
} else {
PRINTF("csma: drop after %d\n", q->transmissions);
free_packet(q);
mac_call_sent_callback(sent, cptr, status, num_tx);
}
} else if(status == MAC_TX_OK) {
PRINTF("csma: rexmit ok %d\n", q->transmissions);
free_packet(q);
mac_call_sent_callback(sent, cptr, status, num_tx);
}
}
/*---------------------------------------------------------------------------*/
static void
send_packet(mac_callback_t sent, void *ptr)
{
struct queued_packet *q;
static uint16_t seqno;
packetbuf_set_attr(PACKETBUF_ATTR_MAC_SEQNO, seqno++);
/* Remember packet for later. */
q = memb_alloc(&packet_memb);
if(q != NULL) {
q->buf = queuebuf_new_from_packetbuf();
if(q != NULL) {
if(packetbuf_attr(PACKETBUF_ATTR_MAX_MAC_TRANSMISSIONS) == 0) {
/* Use default configuration for max transmissions */
q->max_transmissions = CSMA_MAX_MAC_TRANSMISSIONS;
} else {
q->max_transmissions =
packetbuf_attr(PACKETBUF_ATTR_MAX_MAC_TRANSMISSIONS);
}
q->transmissions = 0;
q->collisions = 0;
q->deferrals = 0;
q->sent = sent;
q->cptr = ptr;
NETSTACK_RDC.send(packet_sent, q);
return;
}
memb_free(&packet_memb, q);
}
PRINTF("csma: could not allocate queuebuf, will drop if collision or noack\n");
NETSTACK_RDC.send(sent, ptr);
}
/*---------------------------------------------------------------------------*/
static void
input_packet(void)
{
NETSTACK_NETWORK.input();
}
/*---------------------------------------------------------------------------*/
static int
on(void)
{
return NETSTACK_RDC.on();
}
/*---------------------------------------------------------------------------*/
static int
off(int keep_radio_on)
{
return NETSTACK_RDC.off(keep_radio_on);
}
/*---------------------------------------------------------------------------*/
static unsigned short
channel_check_interval(void)
{
if(NETSTACK_RDC.channel_check_interval) {
return NETSTACK_RDC.channel_check_interval();
}
return 0;
}
/*---------------------------------------------------------------------------*/
static void
init(void)
{
memb_init(&packet_memb);
}
/*---------------------------------------------------------------------------*/
const struct mac_driver csma_driver = {
"CSMA",
init,
send_packet,
input_packet,
on,
off,
channel_check_interval,
};
/*---------------------------------------------------------------------------*/