osd-contiki/core/sys/timesynch.c

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/**
* \addtogroup timesynch
* @{
*/
/*
* Copyright (c) 2007, 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: timesynch.c,v 1.4 2007/12/23 14:57:11 oliverschmidt Exp $
*/
/**
* \file
* A simple time synchronization mechanism
* \author
* Adam Dunkels <adam@sics.se>
*/
#include "sys/timesynch.h"
#include "net/rime/rimebuf.h"
#include "net/rime.h"
#include "dev/simple-cc2420.h"
static const struct mac_driver *mac;
static void (* receiver_callback)(const struct mac_driver *);
#include <stdio.h>
static int authority_level;
static rtimer_clock_t offset;
/*---------------------------------------------------------------------------*/
int
timesynch_authority_level(void)
{
return authority_level;
}
/*---------------------------------------------------------------------------*/
void
timesynch_set_authority_level(int level)
{
authority_level = level;
}
/*---------------------------------------------------------------------------*/
rtimer_clock_t
timesynch_time(void)
{
return rtimer_arch_now() + offset;
}
/*---------------------------------------------------------------------------*/
rtimer_clock_t
timesynch_time_to_rtimer(rtimer_clock_t synched_time)
{
return synched_time - offset;
}
/*---------------------------------------------------------------------------*/
rtimer_clock_t
timesynch_offset(void)
{
return offset;
}
/*---------------------------------------------------------------------------*/
static int
send_packet(void)
{
return mac->send();
}
/*---------------------------------------------------------------------------*/
static void
adjust_offset(rtimer_clock_t authoritative_time, rtimer_clock_t local_time)
{
offset = offset + authoritative_time - local_time;
}
/*---------------------------------------------------------------------------*/
static int
read_packet(void)
{
int len;
len = mac->read();
/* We check the authority level of the sender of the incoming
packet. If the sending node has a lower authority level than we
have, we synchronize to the time of the sending node and set our
own authority level to be one more than the sending node. */
if(simple_cc2420_authority_level_of_sender < authority_level) {
adjust_offset(simple_cc2420_time_of_departure +
simple_cc2420_time_for_transmission,
simple_cc2420_time_of_arrival);
if(simple_cc2420_authority_level_of_sender + 1 != authority_level) {
authority_level = simple_cc2420_authority_level_of_sender + 1;
}
/* XXX the authority level should be increased over time except
for the sink node. */
}
return len;
}
/*---------------------------------------------------------------------------*/
static void
set_receive_function(void (* recv)(const struct mac_driver *))
{
receiver_callback = recv;
}
/*---------------------------------------------------------------------------*/
static int
on(void)
{
return mac->on();
}
/*---------------------------------------------------------------------------*/
static int
off(void)
{
return mac->off();
}
/*---------------------------------------------------------------------------*/
static const struct mac_driver timesynch_driver = {
send_packet,
read_packet,
set_receive_function,
on,
off,
};
/*---------------------------------------------------------------------------*/
static void
input_packet(const struct mac_driver *d)
{
if(receiver_callback) {
receiver_callback(&timesynch_driver);
}
}
/*---------------------------------------------------------------------------*/
const struct mac_driver *
timesynch_init(const struct mac_driver *d)
{
mac = d;
mac->set_receive_function(input_packet);
mac->on();
return &timesynch_driver;
}
/*---------------------------------------------------------------------------*/
/** @} */