platform independent simple slotted tdma mac protocol
observe: uses event timers, not real-time timers!
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fros4943
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858e2682e6
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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: tdma_mac.c,v 1.1 2007/08/31 13:42:22 fros4943 Exp $
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*/
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#include "contiki.h"
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#include "net/mac/tdma_mac.h"
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#include "net/rime/rimebuf.h"
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#include "net/uip-fw.h"
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#include "lib/memb.h"
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#include "lib/list.h"
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#include "node-id.h"
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#include <string.h>
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#include <stdio.h>
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static const struct radio_driver *radio;
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static void (* receiver_callback)(const struct mac_driver *);
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static int id_counter = 0;
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#define DEBUG 1
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#if DEBUG
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/*#include "printf2log.h"*/ /* XXX COOJA specifics */
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#define PRINTF(...) printf(__VA_ARGS__)
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#else
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#define PRINTF(...)
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#endif
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/* TDMA configuration */
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#define MAX_BUFFERED_PACKETS 6
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#define NR_SLOTS 10
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#define SLOT_LENGTH (CLOCK_SECOND) /* Slot length */
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#define GUARD_PERIOD (CLOCK_SECOND / 2) /* Approx. packet transmission time */
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#define MY_SLOT (node_id % NR_SLOTS)
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#define PERIOD_LENGTH (SLOT_LENGTH*NR_SLOTS)
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enum {
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EVENT_PACKET_BUFFERED
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};
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struct buf_packet {
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struct buf_packet *next;
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struct queuebuf *queued_packet;
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int id;
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struct etimer etimer;
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};
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LIST(buf_packet_list);
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MEMB(buf_packet_mem, struct buf_packet, MAX_BUFFERED_PACKETS);
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PROCESS(tdma_process, "TDMA process");
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/*---------------------------------------------------------------------------*/
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PROCESS_THREAD(tdma_process, ev, data)
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{
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PROCESS_BEGIN();
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while(1) {
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PROCESS_YIELD();
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if(ev == EVENT_PACKET_BUFFERED || ev == PROCESS_EVENT_TIMER) {
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struct buf_packet *packet;
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/* Locate packet */
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for(packet = list_head(buf_packet_list); packet != NULL; packet = packet->next) {
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if (etimer_expired(&packet->etimer)) {
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int ret, rest, period_start, my_next_slot;
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clock_time_t now;
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/* Calculate time of our next slot */
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now = clock_time();
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rest = now % PERIOD_LENGTH;
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period_start = now - rest;
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my_next_slot = period_start + MY_SLOT*SLOT_LENGTH;
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/* Transmit if inside our slot, with enough time left */
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if ((now == my_next_slot) ||
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(now > my_next_slot && (now - my_next_slot) < (SLOT_LENGTH-GUARD_PERIOD)))
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{
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PRINTF("SCHEDULE We can deliver right now (%i), slot = (%i <-> %i)\n", now, my_next_slot, my_next_slot + SLOT_LENGTH);
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}
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else
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{
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if (now > my_next_slot) {
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my_next_slot += PERIOD_LENGTH;
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}
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int distance = my_next_slot - now;
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etimer_set(&packet->etimer, distance);
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PRINTF("SCHEDULE Packet #%i rescheduled at %i to %i\n", packet->id, clock_time(), my_next_slot);
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continue;
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}
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/* Clear Rime buffer */
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rimebuf_clear();
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/* Restore packet from buffer */
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if(packet->queued_packet != NULL) {
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queuebuf_to_rimebuf(packet->queued_packet);
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queuebuf_free(packet->queued_packet);
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}
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/* Send packet */
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PRINTF("TDMA_PROC Packet #%i send starting at %i\n", packet->id, clock_time());
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ret = radio->send(rimebuf_hdrptr(), rimebuf_totlen());
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if (ret == UIP_FW_OK) {
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/* Remove transmitted packet */
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list_remove(buf_packet_list, packet);
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memb_free(&buf_packet_mem, packet);
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PRINTF("BUFFER Packet removed, memory freed\n");
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PRINTF("TDMA_PROC Packet #%i sent at %i\n", packet->id, clock_time());
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} else {
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/* Reschedule packet */
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etimer_set(&packet->etimer, SLOT_LENGTH);
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PRINTF("TDMA_PROC Packet #%i forced rescheduled\n", packet->id);
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}
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}
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}
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}
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}
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PROCESS_END();
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}
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/*---------------------------------------------------------------------------*/
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static int
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send(void)
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{
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struct buf_packet *packet;
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packet = (struct buf_packet *)memb_alloc(&buf_packet_mem);
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if (packet == NULL) {
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PRINTF("BUFFER No memory available, packet dropped\n");
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return UIP_FW_DROPPED;
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}
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/* Add to buffered packets list */
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list_add(buf_packet_list, packet);
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PRINTF("BUFFER Packet added, memory allocated\n");
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/* Store packet data */
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packet->queued_packet = queuebuf_new_from_rimebuf();
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if (packet->queued_packet == NULL) {
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list_remove(buf_packet_list, packet);
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memb_free(&buf_packet_mem, packet);
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PRINTF("BUFFER No queue memory available, packet dropped\n");
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return UIP_FW_DROPPED;
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}
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PROCESS_CONTEXT_BEGIN(&tdma_process);
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etimer_set(&packet->etimer, 0);
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PROCESS_CONTEXT_END(&tdma_process);
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/* TODO ID only used for debugging */
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packet->id = id_counter++;
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/* Clear Rime buffer */
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rimebuf_clear();
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process_post(&tdma_process, EVENT_PACKET_BUFFERED, NULL);
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return UIP_FW_OK; /* TODO Return what? */
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}
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/*---------------------------------------------------------------------------*/
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static void
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input(const struct radio_driver *d)
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{
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receiver_callback(&tdma_mac_driver);
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}
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/*---------------------------------------------------------------------------*/
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static int
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read(void)
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{
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int len;
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rimebuf_clear();
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len = radio->read(rimebuf_dataptr(), RIMEBUF_SIZE);
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rimebuf_set_datalen(len);
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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 radio->on();
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}
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/*---------------------------------------------------------------------------*/
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static int
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off(void)
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{
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return radio->off();
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}
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/*---------------------------------------------------------------------------*/
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void
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tdma_mac_init(const struct radio_driver *d)
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{
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memb_init(&buf_packet_mem);
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list_init(buf_packet_list);
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process_start(&tdma_process, NULL);
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radio = d;
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radio->set_receive_function(input);
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radio->on();
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}
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/*---------------------------------------------------------------------------*/
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const struct mac_driver tdma_mac_driver = {
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send,
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read,
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set_receive_function,
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on,
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off,
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};
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@ -0,0 +1,44 @@
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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: tdma_mac.h,v 1.1 2007/08/31 13:42:22 fros4943 Exp $
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*/
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#ifndef __TDMA_MAC_H__
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#define __TDMA_MAC_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 tdma_mac_driver;
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void tdma_mac_init(const struct radio_driver *r);
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#endif /* __TDMA_MAC_H__ */
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