ctdma_mac.c

00001 /*
00002  * Copyright (c) 2007, Swedish Institute of Computer Science.
00003  * All rights reserved.
00004  *
00005  * Redistribution and use in source and binary forms, with or without
00006  * modification, are permitted provided that the following conditions
00007  * are met:
00008  * 1. Redistributions of source code must retain the above copyright
00009  *    notice, this list of conditions and the following disclaimer.
00010  * 2. Redistributions in binary form must reproduce the above copyright
00011  *    notice, this list of conditions and the following disclaimer in the
00012  *    documentation and/or other materials provided with the distribution.
00013  * 3. Neither the name of the Institute nor the names of its contributors
00014  *    may be used to endorse or promote products derived from this software
00015  *    without specific prior written permission.
00016  *
00017  * THIS SOFTWARE IS PROVIDED BY THE INSTITUTE AND CONTRIBUTORS ``AS IS'' AND
00018  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
00019  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
00020  * ARE DISCLAIMED.  IN NO EVENT SHALL THE INSTITUTE OR CONTRIBUTORS BE LIABLE
00021  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
00022  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
00023  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
00024  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
00025  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
00026  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
00027  * SUCH DAMAGE.
00028  *
00029  * This file is part of the Contiki operating system.
00030  *
00031  * $Id: ctdma_mac.c,v 1.6 2010/06/14 19:19:16 adamdunkels Exp $
00032  */
00033 
00034 #include "contiki.h"
00035 #include "net/mac/ctdma_mac.h"
00036 #include "net/packetbuf.h"
00037 #include "net/uip-fw.h"
00038 #include "sys/ctimer.h"
00039 #include "net/rime.h"
00040 #include "lib/memb.h"
00041 #include "lib/list.h"
00042 #include "dev/leds.h"
00043 #include "node-id.h"
00044 
00045 #include <string.h>
00046 #include <stdio.h>
00047 
00048 #define DEBUG 1
00049 #if DEBUG
00050 #define DLEDS_ON(x) leds_on(x)
00051 #define DLEDS_OFF(x) leds_off(x)
00052 #define DLEDS_TOGGLE(x) leds_toggle(x)
00053 #define PRINTF(...) printf(__VA_ARGS__)
00054 #else
00055 #define DLEDS_ON(x)
00056 #define DLEDS_OFF(x)
00057 #define DLEDS_TOGGLE(x)
00058 #define PRINTF(...)
00059 #endif
00060 
00061 /* TDMA */
00062 #define NR_SLOTS 3
00063 #define SLOT_LENGTH (CLOCK_SECOND/3)
00064 #define GUARD_PERIOD (CLOCK_SECOND/12)
00065 
00066 #define MY_SLOT (node_id % NR_SLOTS)
00067 #define PERIOD_LENGTH CLOCK_SECOND
00068 
00069 /* Buffers */
00070 #define NUM_PACKETS 8
00071 uint8_t lastqueued = 0;
00072 uint8_t nextsend = 0;
00073 uint8_t freeslot = 0;
00074 struct queuebuf* data[NUM_PACKETS];
00075 int id[NUM_PACKETS];
00076 
00077 static struct ctimer ctimer;
00078 uint8_t timer_on = 0;
00079 
00080 static const struct radio_driver *radio;
00081 static void (* receiver_callback)(const struct mac_driver *);
00082 static int id_counter = 0;
00083 static int sent_counter = 0;
00084 
00085 /*---------------------------------------------------------------------------*/
00086 static void
00087 transmitter(void *ptr)
00088 {
00089   clock_time_t now, rest, period_start, slot_start;
00090 
00091   /* Calculate slot start time */
00092   now = clock_time();
00093   rest = now % PERIOD_LENGTH;
00094   period_start = now - rest;
00095   slot_start = period_start + MY_SLOT*SLOT_LENGTH;
00096 
00097   /* Check if we are inside our slot */
00098   if (now < slot_start ||
00099       now > slot_start + SLOT_LENGTH - GUARD_PERIOD)
00100   {
00101     PRINTF("TIMER We are outside our slot: %u != [%u,%u]\n", now, slot_start, slot_start + SLOT_LENGTH);
00102     while (now > slot_start + SLOT_LENGTH - GUARD_PERIOD)
00103     {
00104       slot_start += PERIOD_LENGTH;
00105     }
00106     
00107     PRINTF("TIMER Rescheduling until %u\n", slot_start);
00108     ctimer_set(&ctimer, slot_start - clock_time(), transmitter, NULL);
00109     return;
00110   }
00111 
00112   /* Transmit queued packets */
00113   while (nextsend != freeslot)
00114   {
00115     PRINTF("RADIO Transmitting packet #%i\n", id[nextsend]);
00116     if(!radio->send(
00117         queuebuf_dataptr(data[nextsend]), 
00118         queuebuf_datalen(data[nextsend])))
00119     {
00120       sent_counter++;
00121       PRINTF("RADIO Transmit OK for #%i, total=%i\n", id[nextsend], sent_counter);
00122       DLEDS_TOGGLE(LEDS_GREEN);
00123     }
00124     else
00125     {
00126       PRINTF("RADIO Transmit failed for #%i, total=%i\n", id[nextsend], sent_counter);
00127       DLEDS_TOGGLE(LEDS_RED);
00128     }
00129 
00130     nextsend = (nextsend + 1) % NUM_PACKETS;
00131 
00132     /* Recalculate new slot */
00133     if (clock_time() > slot_start + SLOT_LENGTH - GUARD_PERIOD)
00134     {
00135       PRINTF("TIMER No more time to transmit\n");
00136       break;
00137     }
00138   }
00139 
00140   /* Calculate time of our next slot */
00141   slot_start += PERIOD_LENGTH;
00142   PRINTF("TIMER Rescheduling until %u\n", slot_start);
00143   ctimer_set(&ctimer, slot_start - clock_time(), transmitter, NULL);
00144 }
00145 /*---------------------------------------------------------------------------*/
00146 static int
00147 send(void)
00148 {
00149   id_counter++;
00150   
00151   /* Clean up already sent packets */
00152   while (lastqueued != nextsend)
00153   {
00154     PRINTF("BUFFER Cleaning up packet #%i\n", id[lastqueued]);
00155     queuebuf_free(data[lastqueued]);
00156     data[lastqueued] = NULL;
00157 
00158     lastqueued = (lastqueued + 1) % NUM_PACKETS;
00159   }
00160   
00161   if ((freeslot + 1) % NUM_PACKETS == lastqueued)
00162   {
00163     PRINTF("BUFFER Buffer full, dropping packet #%i\n", (id_counter+1));
00164     return UIP_FW_DROPPED;
00165   }
00166 
00167   /* Allocate queue buf for packet */
00168   data[freeslot] = queuebuf_new_from_packetbuf();
00169   id[freeslot] = id_counter;
00170   if (data[freeslot] == NULL)
00171   {
00172     PRINTF("BUFFER Queuebuffer full, dropping packet #%i\n", id[freeslot]);
00173     return UIP_FW_DROPPED;
00174   }
00175   PRINTF("BUFFER Wrote packet #%i to buffer \n", id[freeslot]);
00176 
00177   freeslot = (freeslot + 1) % NUM_PACKETS;
00178   
00179   if (!timer_on) 
00180   {
00181     PRINTF("TIMER Starting timer\n");
00182     ctimer_set(&ctimer, CLOCK_SECOND, transmitter, NULL);
00183     timer_on = 1;
00184   }
00185 
00186   return UIP_FW_OK; /* TODO Return what? */
00187 }
00188 /*---------------------------------------------------------------------------*/
00189 static void
00190 input(const struct radio_driver *d)
00191 {
00192   receiver_callback(&ctdma_mac_driver);
00193 }
00194 /*---------------------------------------------------------------------------*/
00195 static int
00196 read(void)
00197 {
00198   int len;
00199   packetbuf_clear();
00200   len = radio->read(packetbuf_dataptr(), PACKETBUF_SIZE);
00201   packetbuf_set_datalen(len);
00202   return len;
00203 }
00204 /*---------------------------------------------------------------------------*/
00205 static void
00206 set_receive_function(void (* recv)(const struct mac_driver *))
00207 {
00208   receiver_callback = recv;
00209 }
00210 /*---------------------------------------------------------------------------*/
00211 static int
00212 on(void)
00213 {
00214   return radio->on();
00215 }
00216 /*---------------------------------------------------------------------------*/
00217 static int
00218 off(int keep_radio_on)
00219 {
00220   if(keep_radio_on) {
00221     return radio->on();
00222   } else {
00223     return radio->off();
00224   }
00225 }
00226 /*---------------------------------------------------------------------------*/
00227 const struct mac_driver *
00228 ctdma_mac_init(const struct radio_driver *d)
00229 {
00230   int i;
00231   for (i=0; i < NUM_PACKETS; i++)
00232   {
00233     data[i] = NULL;
00234   }
00235 
00236   radio = d;
00237   radio->set_receive_function(input);
00238   radio->on();
00239   return &ctdma_mac_driver;
00240 }
00241 /*---------------------------------------------------------------------------*/
00242 const struct mac_driver ctdma_mac_driver = {
00243   "CTDMA",
00244   ctdma_mac_init,
00245   send,
00246   read,
00247   set_receive_function,
00248   on,
00249   off,
00250 };

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