Contiki 2.6

tdma_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: tdma_mac.c,v 1.8 2010/06/14 19:19:17 adamdunkels Exp $
00032  */
00033 
00034 #include "contiki.h"
00035 #include "net/mac/tdma_mac.h"
00036 #include "net/packetbuf.h"
00037 #include "net/uip-fw.h"
00038 #include "sys/rtimer.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 configuration */
00062 #define NR_SLOTS 3
00063 #define SLOT_LENGTH (RTIMER_SECOND/3)
00064 #define GUARD_PERIOD (RTIMER_SECOND/12)
00065 
00066 #define MY_SLOT (node_id % NR_SLOTS)
00067 #define PERIOD_LENGTH RTIMER_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 rtimer rtimer;
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 char
00087 transmitter(struct rtimer *t, void *ptr)
00088 {
00089   int r;
00090   rtimer_clock_t now, rest, period_start, slot_start;
00091 
00092   /* Calculate slot start time */
00093   now = RTIMER_NOW();
00094   rest = now % PERIOD_LENGTH;
00095   period_start = now - rest;
00096   slot_start = period_start + MY_SLOT*SLOT_LENGTH;
00097 
00098   /* Check if we are inside our slot */
00099   if(now < slot_start ||
00100       now > slot_start + SLOT_LENGTH - GUARD_PERIOD) {
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       slot_start += PERIOD_LENGTH;
00104     }
00105 
00106     PRINTF("TIMER Rescheduling until %u\n", slot_start);
00107     r = rtimer_set(&rtimer, slot_start, 1,
00108         (void (*)(struct rtimer *, void *))transmitter, NULL);
00109     if(r) {
00110       PRINTF("TIMER Error #1: %d\n", r);
00111     }
00112 
00113     return 1;
00114   }
00115 
00116   /* Transmit queued packets */
00117   while(nextsend != freeslot) {
00118     PRINTF("RADIO Transmitting packet #%i\n", id[nextsend]);
00119     if(!radio->send(queuebuf_dataptr(data[nextsend]),
00120                     queuebuf_datalen(data[nextsend]))) {
00121       sent_counter++;
00122       PRINTF("RADIO Transmit OK for #%i, total=%i\n", id[nextsend], sent_counter);
00123       DLEDS_TOGGLE(LEDS_GREEN);
00124     } else {
00125       PRINTF("RADIO Transmit failed for #%i, total=%i\n", id[nextsend], sent_counter);
00126       DLEDS_TOGGLE(LEDS_RED);
00127     }
00128 
00129     nextsend = (nextsend + 1) % NUM_PACKETS;
00130 
00131     /* Recalculate new slot */
00132     if(RTIMER_NOW() > slot_start + SLOT_LENGTH - GUARD_PERIOD) {
00133       PRINTF("TIMER No more time to transmit\n");
00134       break;
00135     }
00136   }
00137 
00138   /* Calculate time of our next slot */
00139   slot_start += PERIOD_LENGTH;
00140   PRINTF("TIMER Rescheduling until %u\n", slot_start);
00141   r = rtimer_set(&rtimer, slot_start, 1,
00142       (void (*)(struct rtimer *, void *))transmitter, NULL);
00143   if(r) {
00144     PRINTF("TIMER Error #2: %d\n", r);
00145   }
00146 
00147   return 0;
00148 }
00149 /*---------------------------------------------------------------------------*/
00150 static int
00151 send(void)
00152 {
00153   int r;
00154   id_counter++;
00155 
00156   /* Clean up already sent packets */
00157   while(lastqueued != nextsend) {
00158     PRINTF("BUFFER Cleaning up packet #%i\n", id[lastqueued]);
00159     queuebuf_free(data[lastqueued]);
00160     data[lastqueued] = NULL;
00161 
00162     lastqueued = (lastqueued + 1) % NUM_PACKETS;
00163   }
00164 
00165   if((freeslot + 1) % NUM_PACKETS == lastqueued) {
00166     PRINTF("BUFFER Buffer full, dropping packet #%i\n", (id_counter+1));
00167     return UIP_FW_DROPPED;
00168   }
00169 
00170   /* Allocate queue buf for packet */
00171   data[freeslot] = queuebuf_new_from_packetbuf();
00172   id[freeslot] = id_counter;
00173   if(data[freeslot] == NULL) {
00174     PRINTF("BUFFER Queuebuffer full, dropping packet #%i\n", id[freeslot]);
00175     return UIP_FW_DROPPED;
00176   }
00177   PRINTF("BUFFER Wrote packet #%i to buffer \n", id[freeslot]);
00178 
00179   freeslot = (freeslot + 1) % NUM_PACKETS;
00180 
00181   if(!timer_on) {
00182     PRINTF("TIMER Starting timer\n");
00183     r = rtimer_set(&rtimer, RTIMER_NOW() + RTIMER_SECOND, 1,
00184         (void (*)(struct rtimer *, void *))transmitter, NULL);
00185     if(r) {
00186       PRINTF("TIMER Error #3: %d\n", r);
00187     } else {
00188       timer_on = 1;
00189     }
00190   }
00191 
00192   return UIP_FW_OK; /* TODO Return what? */
00193 }
00194 /*---------------------------------------------------------------------------*/
00195 static void
00196 input(const struct radio_driver *d)
00197 {
00198   receiver_callback(&tdma_mac_driver);
00199 }
00200 /*---------------------------------------------------------------------------*/
00201 static int
00202 read(void)
00203 {
00204   int len;
00205   packetbuf_clear();
00206   len = radio->read(packetbuf_dataptr(), PACKETBUF_SIZE);
00207   packetbuf_set_datalen(len);
00208   return len;
00209 }
00210 /*---------------------------------------------------------------------------*/
00211 static void
00212 set_receive_function(void (* recv)(const struct mac_driver *))
00213 {
00214   receiver_callback = recv;
00215 }
00216 /*---------------------------------------------------------------------------*/
00217 static int
00218 on(void)
00219 {
00220   return radio->on();
00221 }
00222 /*---------------------------------------------------------------------------*/
00223 static int
00224 off(int keep_radio_on)
00225 {
00226   if(keep_radio_on) {
00227     return radio->on();
00228   } else {
00229     return radio->off();
00230   }
00231 }
00232 /*---------------------------------------------------------------------------*/
00233 const struct mac_driver *
00234 tdma_mac_init(const struct radio_driver *d)
00235 {
00236   int i;
00237   for(i = 0; i < NUM_PACKETS; i++) {
00238     data[i] = NULL;
00239   }
00240 
00241   radio = d;
00242   radio->set_receive_function(input);
00243   radio->on();
00244 
00245   return &tdma_mac_driver;
00246 }
00247 /*---------------------------------------------------------------------------*/
00248 const struct mac_driver tdma_mac_driver = {
00249     "TDMA MAC",
00250     tdma_mac_init,
00251     send,
00252     read,
00253     set_receive_function,
00254     on,
00255     off,
00256 };