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osd-contiki/core/net/mac/csma.c

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/*
* 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.
*
*/
/**
* \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 "sys/clock.h"
#include "lib/random.h"
#include "net/netstack.h"
#include "lib/list.h"
#include "lib/memb.h"
#include <string.h>
#include <stdio.h>
#define DEBUG 0
#if DEBUG
#include <stdio.h>
#define PRINTF(...) printf(__VA_ARGS__)
#else /* DEBUG */
#define PRINTF(...)
#endif /* DEBUG */
/* Constants of the IEEE 802.15.4 standard */
/* macMinBE: Initial backoff exponent. Range 0--CSMA_MAX_BE */
#ifdef CSMA_CONF_MIN_BE
#define CSMA_MIN_BE CSMA_CONF_MIN_BE
#else
#define CSMA_MIN_BE 0
#endif
/* macMaxBE: Maximum backoff exponent. Range 3--8 */
#ifdef CSMA_CONF_MAX_BE
#define CSMA_MAX_BE CSMA_CONF_MAX_BE
#else
#define CSMA_MAX_BE 4
#endif
/* macMaxCSMABackoffs: Maximum number of backoffs in case of channel busy/collision. Range 0--5 */
#ifdef CSMA_CONF_MAX_BACKOFF
#define CSMA_MAX_BACKOFF CSMA_CONF_MAX_BACKOFF
#else
#define CSMA_MAX_BACKOFF 5
#endif
/* macMaxFrameRetries: Maximum number of re-transmissions attampts. Range 0--7 */
#ifdef CSMA_CONF_MAX_FRAME_RETRIES
#define CSMA_MAX_MAX_FRAME_RETRIES CSMA_CONF_MAX_FRAME_RETRIES
#else
#define CSMA_MAX_MAX_FRAME_RETRIES 7
#endif
/* Packet metadata */
struct qbuf_metadata {
mac_callback_t sent;
void *cptr;
uint8_t max_transmissions;
};
/* Every neighbor has its own packet queue */
struct neighbor_queue {
struct neighbor_queue *next;
linkaddr_t addr;
struct ctimer transmit_timer;
uint8_t transmissions;
uint8_t collisions;
LIST_STRUCT(queued_packet_list);
};
/* The maximum number of co-existing neighbor queues */
#ifdef CSMA_CONF_MAX_NEIGHBOR_QUEUES
#define CSMA_MAX_NEIGHBOR_QUEUES CSMA_CONF_MAX_NEIGHBOR_QUEUES
#else
#define CSMA_MAX_NEIGHBOR_QUEUES 2
#endif /* CSMA_CONF_MAX_NEIGHBOR_QUEUES */
/* The maximum number of pending packet per neighbor */
#ifdef CSMA_CONF_MAX_PACKET_PER_NEIGHBOR
#define CSMA_MAX_PACKET_PER_NEIGHBOR CSMA_CONF_MAX_PACKET_PER_NEIGHBOR
#else
#define CSMA_MAX_PACKET_PER_NEIGHBOR MAX_QUEUED_PACKETS
#endif /* CSMA_CONF_MAX_PACKET_PER_NEIGHBOR */
#define MAX_QUEUED_PACKETS QUEUEBUF_NUM
MEMB(neighbor_memb, struct neighbor_queue, CSMA_MAX_NEIGHBOR_QUEUES);
MEMB(packet_memb, struct rdc_buf_list, MAX_QUEUED_PACKETS);
MEMB(metadata_memb, struct qbuf_metadata, MAX_QUEUED_PACKETS);
LIST(neighbor_list);
static void packet_sent(void *ptr, int status, int num_transmissions);
static void transmit_packet_list(void *ptr);
/*---------------------------------------------------------------------------*/
static struct neighbor_queue *
neighbor_queue_from_addr(const linkaddr_t *addr)
{
struct neighbor_queue *n = list_head(neighbor_list);
while(n != NULL) {
if(linkaddr_cmp(&n->addr, addr)) {
return n;
}
n = list_item_next(n);
}
return NULL;
}
/*---------------------------------------------------------------------------*/
static clock_time_t
backoff_period(void)
{
clock_time_t time;
/* 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, we use
* the default in IEEE 802.15.4: aUnitBackoffPeriod which is
* 20 symbols i.e. 320 usec. That is, 1/3125 second. */
if(time == 0) {
time = MAX(CLOCK_SECOND / 3125, 1);
}
return time;
}
/*---------------------------------------------------------------------------*/
static void
transmit_packet_list(void *ptr)
{
struct neighbor_queue *n = ptr;
if(n) {
struct rdc_buf_list *q = list_head(n->queued_packet_list);
if(q != NULL) {
PRINTF("csma: preparing number %d %p, queue len %d\n", n->transmissions, q,
list_length(n->queued_packet_list));
/* Send packets in the neighbor's list */
NETSTACK_RDC.send_list(packet_sent, n, q);
}
}
}
/*---------------------------------------------------------------------------*/
static void
schedule_transmission(struct neighbor_queue *n)
{
clock_time_t delay;
int backoff_exponent; /* BE in IEEE 802.15.4 */
backoff_exponent = MIN(n->collisions, CSMA_MAX_BE);
/* Compute max delay as per IEEE 802.15.4: 2^BE-1 backoff periods */
delay = ((1 << backoff_exponent) - 1) * backoff_period();
if(delay > 0) {
/* Pick a time for next transmission */
delay = random_rand() % delay;
}
PRINTF("csma: scheduling transmission in %u ticks, NB=%u, BE=%u\n",
(unsigned)delay, n->collisions, backoff_exponent);
ctimer_set(&n->transmit_timer, delay, transmit_packet_list, n);
}
/*---------------------------------------------------------------------------*/
static void
free_packet(struct neighbor_queue *n, struct rdc_buf_list *p, int status)
{
if(p != NULL) {
/* Remove packet from list and deallocate */
list_remove(n->queued_packet_list, p);
queuebuf_free(p->buf);
memb_free(&metadata_memb, p->ptr);
memb_free(&packet_memb, p);
PRINTF("csma: free_queued_packet, queue length %d, free packets %d\n",
list_length(n->queued_packet_list), memb_numfree(&packet_memb));
if(list_head(n->queued_packet_list) != NULL) {
/* There is a next packet. We reset current tx information */
n->transmissions = 0;
n->collisions = CSMA_MIN_BE;
/* Schedule next transmissions */
schedule_transmission(n);
} else {
/* This was the last packet in the queue, we free the neighbor */
ctimer_stop(&n->transmit_timer);
list_remove(neighbor_list, n);
memb_free(&neighbor_memb, n);
}
}
}
/*---------------------------------------------------------------------------*/
static void
tx_done(int status, struct rdc_buf_list *q, struct neighbor_queue *n)
{
mac_callback_t sent;
struct qbuf_metadata *metadata;
void *cptr;
uint8_t ntx;
metadata = (struct qbuf_metadata *)q->ptr;
sent = metadata->sent;
cptr = metadata->cptr;
ntx = n->transmissions;
switch(status) {
case MAC_TX_OK:
PRINTF("csma: rexmit ok %d\n", n->transmissions);
break;
case MAC_TX_COLLISION:
case MAC_TX_NOACK:
PRINTF("csma: drop with status %d after %d transmissions, %d collisions\n",
status, n->transmissions, n->collisions);
break;
default:
PRINTF("csma: rexmit failed %d: %d\n", n->transmissions, status);
break;
}
free_packet(n, q, status);
mac_call_sent_callback(sent, cptr, status, ntx);
}
/*---------------------------------------------------------------------------*/
static void
rexmit(struct rdc_buf_list *q, struct neighbor_queue *n)
{
schedule_transmission(n);
/* This is needed to correctly attribute energy that we spent
transmitting this packet. */
queuebuf_update_attr_from_packetbuf(q->buf);
}
/*---------------------------------------------------------------------------*/
static void
collision(struct rdc_buf_list *q, struct neighbor_queue *n,
int num_transmissions)
{
struct qbuf_metadata *metadata;
metadata = (struct qbuf_metadata *)q->ptr;
n->collisions += num_transmissions;
if(n->collisions > CSMA_MAX_BACKOFF) {
n->collisions = CSMA_MIN_BE;
/* Increment to indicate a next retry */
n->transmissions++;
}
if(n->transmissions >= metadata->max_transmissions) {
tx_done(MAC_TX_COLLISION, q, n);
} else {
PRINTF("csma: rexmit collision %d\n", n->transmissions);
rexmit(q, n);
}
}
/*---------------------------------------------------------------------------*/
static void
noack(struct rdc_buf_list *q, struct neighbor_queue *n, int num_transmissions)
{
struct qbuf_metadata *metadata;
metadata = (struct qbuf_metadata *)q->ptr;
n->collisions = CSMA_MIN_BE;
n->transmissions += num_transmissions;
if(n->transmissions >= metadata->max_transmissions) {
tx_done(MAC_TX_NOACK, q, n);
} else {
PRINTF("csma: rexmit noack %d\n", n->transmissions);
rexmit(q, n);
}
}
/*---------------------------------------------------------------------------*/
static void
tx_ok(struct rdc_buf_list *q, struct neighbor_queue *n, int num_transmissions)
{
n->collisions = CSMA_MIN_BE;
n->transmissions += num_transmissions;
tx_done(MAC_TX_OK, q, n);
}
/*---------------------------------------------------------------------------*/
static void
packet_sent(void *ptr, int status, int num_transmissions)
{
struct neighbor_queue *n;
struct rdc_buf_list *q;
n = ptr;
if(n == NULL) {
return;
}
/* Find out what packet this callback refers to */
for(q = list_head(n->queued_packet_list);
q != NULL; q = list_item_next(q)) {
if(queuebuf_attr(q->buf, PACKETBUF_ATTR_MAC_SEQNO) ==
packetbuf_attr(PACKETBUF_ATTR_MAC_SEQNO)) {
break;
}
}
if(q == NULL) {
PRINTF("csma: seqno %d not found\n",
packetbuf_attr(PACKETBUF_ATTR_MAC_SEQNO));
return;
} else if(q->ptr == NULL) {
PRINTF("csma: no metadata\n");
return;
}
switch(status) {
case MAC_TX_OK:
tx_ok(q, n, num_transmissions);
break;
case MAC_TX_NOACK:
noack(q, n, num_transmissions);
break;
case MAC_TX_COLLISION:
collision(q, n, num_transmissions);
break;
case MAC_TX_DEFERRED:
break;
default:
tx_done(status, q, n);
break;
}
}
/*---------------------------------------------------------------------------*/
static void
send_packet(mac_callback_t sent, void *ptr)
{
struct rdc_buf_list *q;
struct neighbor_queue *n;
static uint8_t initialized = 0;
static uint16_t seqno;
const linkaddr_t *addr = packetbuf_addr(PACKETBUF_ADDR_RECEIVER);
if(!initialized) {
initialized = 1;
/* Initialize the sequence number to a random value as per 802.15.4. */
seqno = random_rand();
}
if(seqno == 0) {
/* PACKETBUF_ATTR_MAC_SEQNO cannot be zero, due to a pecuilarity
in framer-802154.c. */
seqno++;
}
packetbuf_set_attr(PACKETBUF_ATTR_MAC_SEQNO, seqno++);
/* Look for the neighbor entry */
n = neighbor_queue_from_addr(addr);
if(n == NULL) {
/* Allocate a new neighbor entry */
n = memb_alloc(&neighbor_memb);
if(n != NULL) {
/* Init neighbor entry */
linkaddr_copy(&n->addr, addr);
n->transmissions = 0;
n->collisions = CSMA_MIN_BE;
/* Init packet list for this neighbor */
LIST_STRUCT_INIT(n, queued_packet_list);
/* Add neighbor to the list */
list_add(neighbor_list, n);
}
}
if(n != NULL) {
/* Add packet to the neighbor's queue */
if(list_length(n->queued_packet_list) < CSMA_MAX_PACKET_PER_NEIGHBOR) {
q = memb_alloc(&packet_memb);
if(q != NULL) {
q->ptr = memb_alloc(&metadata_memb);
if(q->ptr != NULL) {
q->buf = queuebuf_new_from_packetbuf();
if(q->buf != NULL) {
struct qbuf_metadata *metadata = (struct qbuf_metadata *)q->ptr;
/* Neighbor and packet successfully allocated */
if(packetbuf_attr(PACKETBUF_ATTR_MAX_MAC_TRANSMISSIONS) == 0) {
/* Use default configuration for max transmissions */
metadata->max_transmissions = CSMA_MAX_MAX_FRAME_RETRIES + 1;
} else {
metadata->max_transmissions =
packetbuf_attr(PACKETBUF_ATTR_MAX_MAC_TRANSMISSIONS);
}
metadata->sent = sent;
metadata->cptr = ptr;
#if PACKETBUF_WITH_PACKET_TYPE
if(packetbuf_attr(PACKETBUF_ATTR_PACKET_TYPE) ==
PACKETBUF_ATTR_PACKET_TYPE_ACK) {
list_push(n->queued_packet_list, q);
} else
#endif
{
list_add(n->queued_packet_list, q);
}
PRINTF("csma: send_packet, queue length %d, free packets %d\n",
list_length(n->queued_packet_list), memb_numfree(&packet_memb));
/* If q is the first packet in the neighbor's queue, send asap */
if(list_head(n->queued_packet_list) == q) {
schedule_transmission(n);
}
return;
}
memb_free(&metadata_memb, q->ptr);
PRINTF("csma: could not allocate queuebuf, dropping packet\n");
}
memb_free(&packet_memb, q);
PRINTF("csma: could not allocate queuebuf, dropping packet\n");
}
/* The packet allocation failed. Remove and free neighbor entry if empty. */
if(list_length(n->queued_packet_list) == 0) {
list_remove(neighbor_list, n);
memb_free(&neighbor_memb, n);
}
} else {
PRINTF("csma: Neighbor queue full\n");
}
PRINTF("csma: could not allocate packet, dropping packet\n");
} else {
PRINTF("csma: could not allocate neighbor, dropping packet\n");
}
mac_call_sent_callback(sent, ptr, MAC_TX_ERR, 1);
}
/*---------------------------------------------------------------------------*/
static void
input_packet(void)
{
NETSTACK_LLSEC.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);
memb_init(&metadata_memb);
memb_init(&neighbor_memb);
}
/*---------------------------------------------------------------------------*/
const struct mac_driver csma_driver = {
"CSMA",
init,
send_packet,
input_packet,
on,
off,
channel_check_interval,
};
/*---------------------------------------------------------------------------*/
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