osd-contiki/core/net/mac/csma.c
adamdunkels e34eb54960 A work-in-progress rework of the Contiki MAC and radio layers. The
main ideas are:

* Separates the Contiki low-layer network stack into four layers:
  network (e.g. sicslowpan / rime), Medium Access Control MAC
  (e.g. CSMA), Radio Duty Cycling RDC (e.g. ContikiMAC, X-MAC), and
  radio (e.g. cc2420).
* Introduces a new way to configure the network stack. Four #defines
  that specify what mechanism/protocol/driver to use at the four
  layers: NETSTACK_CONF_NETWORK, NETSTACK_CONF_MAC, NETSTACK_CONF_RDC,
  NETSTACK_CONF_RADIO.
* Adds a callback mechanism to inform the MAC and network layers about
  the fate of a transmitted packet: if the packet was not possible to
  transmit, the cause of the failure is reported, and if the packets
  was successfully transmitted, the number of tries before it was
  finally transmitted is reported.
* NULL-protocols at both the MAC and RDC layers: nullmac and nullrdc,
  which can be used when MAC and RDC functionality is not needed.
* Extends the radio API with three new functions that enable more
  efficient radio duty cycling protocols: channel check, pending
  packet, and receiving packet.
* New initialization mechanism, which takes advantage of the NETSTACK
  #defines.
2010-02-18 21:48:39 +00:00

281 lines
7.6 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 1.6 2010/02/18 21:48:39 adamdunkels Exp $
*/
/**
* \file
* A MAC
* \author
* Adam Dunkels <adam@sics.se>
*/
#define CSMA_CONF_REXMIT 1
#include "net/mac/csma.h"
#include "net/rime/packetbuf.h"
#include "net/rime/queuebuf.h"
#include "net/rime/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 */
struct queued_packet {
struct queued_packet *next;
struct queuebuf *buf;
struct ctimer retransmit_timer;
mac_callback_t sent;
void *cptr;
uint8_t transmissions;
};
#define MAX_RETRANSMITS 2
#define MAX_QUEUED_PACKETS 8
MEMB(packet_memb, struct queued_packet, MAX_QUEUED_PACKETS);
/*---------------------------------------------------------------------------*/
#if CSMA_CONF_REXMIT
static void
free_packet(struct queued_packet *q)
{
queuebuf_free(q->buf);
memb_free(&packet_memb, q);
}
static void retransmit_packet(void *ptr);
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;
sent = q->sent;
cptr = q->cptr;
num_tx = q->transmissions;
if(status != MAC_TX_OK) {
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", ret, q->transmissions);
}
time = NETSTACK_RDC.channel_check_interval();
if(time == 0) {
time = CLOCK_SECOND;
}
time = time + (random_rand() % (q->transmissions * 3 * time));
if(q->transmissions - 1 < MAX_RETRANSMITS) {
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, ptr, status, num_tx);
}
} else {
PRINTF("csma: rexmit ok %d\n", q->transmissions);
free_packet(q);
mac_call_sent_callback(sent, ptr, status, num_tx);
}
}
static void
retransmit_packet(void *ptr)
{
struct queued_packet *q = ptr;
queuebuf_to_packetbuf(q->buf);
q->transmissions++;
NETSTACK_RDC.send(packet_sent, q);
}
/*---------------------------------------------------------------------------*/
static void
sent_packet_1(void *ptr, int status, int num_transmissions)
{
struct queued_packet *q = ptr;
clock_time_t time;
rimeaddr_t receiver;
rimeaddr_copy(&receiver, packetbuf_addr(PACKETBUF_ADDR_RECEIVER));
if(rimeaddr_cmp(&receiver, &rimeaddr_null)) {
PRINTF("broadcast/");
}
if(status != MAC_TX_OK) {
switch(status) {
case MAC_TX_COLLISION:
PRINTF("csma: collision\n");
break;
case MAC_TX_NOACK:
PRINTF("csma: noack\n");
break;
default:
PRINTF("csma: err %d\n", ret);
}
} else {
PRINTF("csma: ok\n");
}
/* Check if we saw a collission, and if we have a queuebuf with the
packet available. Only retransmit unicast packets. Retransmit
only once, for now. */
if((status == MAC_TX_COLLISION || status == MAC_TX_NOACK) &&
!rimeaddr_cmp(&receiver, &rimeaddr_null)) {
/* If the packet couldn't be sent because of a collision or the
lack of an ACK, we let the other transmissions get through
before we try again. */
time = NETSTACK_RDC.channel_check_interval();
if(time == 0) {
time = CLOCK_SECOND;
}
time = time + (random_rand() % (3 * time));
ctimer_set(&q->retransmit_timer, time,
retransmit_packet, q);
} else {
mac_callback_t sent;
void *cptr;
int num_tx;
sent = q->sent;
cptr = q->cptr;
num_tx = q->transmissions;
free_packet(q);
mac_call_sent_callback(sent, ptr, status, num_tx);
}
}
/*---------------------------------------------------------------------------*/
static void
send_packet(mac_callback_t sent, void *ptr)
{
struct queued_packet *q;
/* Remember packet for later. */
q = memb_alloc(&packet_memb);
if(q != NULL) {
q->buf = queuebuf_new_from_packetbuf();
if(q != NULL) {
q->transmissions = 1;
q->sent = sent;
q->cptr = ptr;
NETSTACK_RDC.send(sent_packet_1, 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);
}
#else /* CSMA_CONF_REXMIT */
static void
send_packet(mac_callback_t sent, void *ptr)
{
NETSTACK_RDC.send(NULL, NULL);
}
#endif /* CSMA_CONF_REXMIT */
/*---------------------------------------------------------------------------*/
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;
}
/*---------------------------------------------------------------------------*/
#define NAMEBUF_LEN 16
static char namebuf[NAMEBUF_LEN];
static void
init(void)
{
memb_init(&packet_memb);
/* PRINTF("CSMA with MAC %s, channel check rate %d Hz\n", mac->name,
CLOCK_SECOND / channel_check_interval());*/
memcpy(namebuf, "CSMA ", 5);
memcpy(namebuf + 5, NETSTACK_RDC.name, NAMEBUF_LEN - 6);
}
/*---------------------------------------------------------------------------*/
const struct mac_driver csma_driver = {
namebuf,
init,
send_packet,
input_packet,
on,
off,
channel_check_interval,
};
/*---------------------------------------------------------------------------*/