145 lines
5.3 KiB
C
145 lines
5.3 KiB
C
/**
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* \addtogroup sys
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* @{
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*/
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/**
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* \defgroup timesynch Implicit network time synchronization
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* @{
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*
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* This crude and simple network time synchronization module
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* synchronizes clocks of all nodes in a network. The time
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* synchronization is implicit in that no explicit time
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* synchronization messages are sent: the module relies on the
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* underlying network device driver to timestamp all radio messages,
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* both outgoing and incoming. The code currently only works on the
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* Tmote Sky platform and the simple-cc2420 driver.
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*
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* Every node has an authority level, which is included in every
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* outgoing packet. If a message is received from a node with higher
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* authority (lower authority number), the node adjusts its clock
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* towards the clock of the sending node.
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*
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* The timesynch module is implemented as a meta-MAC protocol, so that
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* the module is invoked for every incoming packet.
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*
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*/
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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: timesynch.h,v 1.1 2007/12/16 14:29:56 adamdunkels Exp $
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*/
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/**
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* \file
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* Header file for a simple time synchronization mechanism
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* \author
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* Adam Dunkels <adam@sics.se>
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*/
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#ifndef __TIMESYNCH_H__
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#define __TIMESYNCH_H__
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#include "net/mac/mac.h"
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#include "sys/rtimer.h"
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/**
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* \brief Initialize the timesynch module; should be called during the MAC initialization procedure
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* \param r The underlying MAC driver
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* \return A pointer to the timesynch module's meta MAC driver
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*
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* This function initializes the timesynch module. The
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* function should be called as part of the MAC
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* initialization procedure.
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*
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*/
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const struct mac_driver *timesynch_init(const struct mac_driver *r);
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/**
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* \brief Get the current time-synchronized time
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* \return The current time-synchronized time
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*
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* This function returns the current time-synchronized
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* time.
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*
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*/
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rtimer_clock_t timesynch_time(void);
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/**
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* \brief Get the current time-synchronized rtimer time, suitable for use with the rtimer module
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* \return The current time-synchronized rtimer time
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*
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* This function returns the (local) rtimer-equivalent
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* time corresponding to the current time-synchronized
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* (global) time. The rtimer-equivalent time is used for
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* setting rtimer timers that are synchronized to other
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* nodes in the network.
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*
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*/
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rtimer_clock_t timesynch_time_to_rtimer(rtimer_clock_t synched_time);
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/**
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* \brief Get the current time-synchronized offset from the rtimer clock, which is used mainly for debugging
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* \return The current time-synchronized offset from the rtimer clock
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*
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* This function returns the current time-synchronized
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* offset from the rtimer arch clock. This is mainly
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* useful for debugging the timesynch module.
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*
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*/
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rtimer_clock_t timesynch_offset(void);
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/**
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* \brief Get the current authority level of the time-synchronized time
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* \return The current authority level of the time-synchronized time
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*
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* This function returns the current authority level of
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* the time-synchronized time. A node with a lower
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* authority level is defined to have a better notion of
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* time than a node with a higher authority
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* level. Authority level 0 is best and should be used by
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* a sink node that has a connection to an outside,
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* "true", clock source.
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*
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*/
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int timesynch_authority_level(void);
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/**
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* \brief Set the authority level of the current time
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* \param level The authority level
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*/
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void timesynch_set_authority_level(int level);
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#endif /* __TIMESYNCH_H__ */
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/** @} */
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/** @} */
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