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Add a Trickle Timer Library (RFC 6206)

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George Oikonomou 2012-04-16 10:27:43 +01:00 committed by George Oikonomou
parent 0d913d0d61
commit ffeceb9164
3 changed files with 899 additions and 1 deletions
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2
Makefile.include
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@ -59,7 +59,7 @@ include $(CONTIKI)/core/net/mac/Makefile.mac
SYSTEM = process.c procinit.c autostart.c elfloader.c profile.c \ SYSTEM = process.c procinit.c autostart.c elfloader.c profile.c \
timetable.c timetable-aggregate.c compower.c serial-line.c timetable.c timetable-aggregate.c compower.c serial-line.c
THREADS = mt.c THREADS = mt.c
LIBS = memb.c mmem.c timer.c list.c etimer.c ctimer.c energest.c rtimer.c stimer.c \ LIBS = memb.c mmem.c timer.c list.c etimer.c ctimer.c energest.c rtimer.c stimer.c trickle-timer.c \
print-stats.c ifft.c crc16.c random.c checkpoint.c ringbuf.c settings.c print-stats.c ifft.c crc16.c random.c checkpoint.c ringbuf.c settings.c
DEV = nullradio.c DEV = nullradio.c

407
core/lib/trickle-timer.c Executable file
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@ -0,0 +1,407 @@
/**
* \addtogroup trickle-timer
* @{
*/
/**
* \file
* Trickle timer library implementation.
* \author
* George Oikonomou - <oikonomou@users.sourceforge.net>
*/
/*
* Copyright (c) 2012, George Oikonomou - <oikonomou@users.sourceforge.net>
* 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 copyright holder 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 COPYRIGHT HOLDERS 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
* COPYRIGHT HOLDER 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.
*/
#include "contiki-conf.h"
#include "lib/trickle-timer.h"
#include "sys/ctimer.h"
#include "sys/cc.h"
#include "lib/random.h"
/*---------------------------------------------------------------------------*/
#define DEBUG 0
#if DEBUG
#include <stdio.h>
#define PRINTF(...) printf(__VA_ARGS__)
#else
#define PRINTF(...)
#endif
/*---------------------------------------------------------------------------*/
/**
* \brief Wide randoms for platforms using a 4-byte wide clock
* (see ::TRICKLE_TIMER_WIDE_RAND)
*/
#if TRICKLE_TIMER_WIDE_RAND
#define tt_rand() wide_rand()
#else
#define tt_rand() random_rand()
#endif
/*---------------------------------------------------------------------------*/
/* Declarations of variables of local interest */
/*---------------------------------------------------------------------------*/
static struct trickle_timer *loctt; /* Pointer to a struct for local use */
static clock_time_t loc_clock; /* A local, general-purpose placeholder */
static void fire(void *ptr);
static void double_interval(void *ptr);
/*---------------------------------------------------------------------------*/
/* Local utilities and functions to be used as ctimer callbacks */
/*---------------------------------------------------------------------------*/
#if TRICKLE_TIMER_WIDE_RAND
/* Returns a 4-byte wide, unsigned random number */
static uint32_t
wide_rand()
{
return ((uint32_t)random_rand() << 16 | random_rand());
}
#endif
/*---------------------------------------------------------------------------*/
/*
* Returns the maximum sane Imax value for a given Imin
*
* This function is a variant of a fairly standard 'Count Leading Zeros'. It
* has three flavours. The most suitable one for a specific platform can be
* configured by changing the value of TRICKLE_TIMER_CONF_MAX_IMAX_WIDTH
* in the platform's contiki-conf.h
*/
#if TRICKLE_TIMER_ERROR_CHECKING
static uint8_t
max_imax(clock_time_t value)
{
uint8_t zeros = 0;
#if (TRICKLE_TIMER_MAX_IMAX_WIDTH==TRICKLE_TIMER_MAX_IMAX_GENERIC)
uint8_t i;
clock_time_t mask = 0xFFFF;
value--;
for(i = sizeof(clock_time_t) << 2; i > 0; i >>= 1) {
if((value & (mask <<= i)) == 0) {
zeros += i;
value <<= i;
}
}
#elif (TRICKLE_TIMER_MAX_IMAX_WIDTH==TRICKLE_TIMER_MAX_IMAX_16_BIT)
if((value & 0xFF00) == 0) {
zeros += 8;
value <<= 8;
}
if((value & 0xF000) == 0) {
zeros += 4;
value <<= 4;
}
if((value & 0xC000) == 0) {
zeros += 2;
value <<= 2;
}
if((value & 0x8000) == 0) {
zeros++;
}
#elif (TRICKLE_TIMER_MAX_IMAX_WIDTH==TRICKLE_TIMER_MAX_IMAX_32_BIT)
if((value & 0xFFFF0000) == 0) {
zeros += 16;
value <<= 16;
}
if((value & 0xFF000000) == 0) {
zeros += 8;
value <<= 8;
}
if((value & 0xF0000000) == 0) {
zeros += 4;
value <<= 4;
}
if((value & 0xC0000000) == 0) {
zeros += 2;
value <<= 2;
}
if((value & 0x80000000) == 0) {
zeros += 1;
}
#endif
return zeros - 1; /* Always non-negative due to the range of 'value' */
}
#endif /* TRICKLE_TIMER_ERROR_CHECKING */
/*---------------------------------------------------------------------------*/
/* Returns a random time point t in [I/2 , I) */
static clock_time_t
get_t(clock_time_t i_cur)
{
i_cur >>= 1;
PRINTF("trickle_timer get t: [%lu, %lu)\n", (unsigned long)i_cur,
(unsigned long)(i_cur << 1));
return i_cur + (tt_rand() % i_cur);
}
/*---------------------------------------------------------------------------*/
static void
schedule_for_end(struct trickle_timer *tt)
{
/* Reset our ctimer, schedule interval_end to run at time I */
clock_time_t now = clock_time();
loc_clock = TRICKLE_TIMER_INTERVAL_END(tt) - now;
PRINTF("trickle_timer sched for end: at %lu, end in %ld\n",
(unsigned long)clock_time(), (signed long)loc_clock);
/* Interval's end will happen in loc_clock ticks. Make sure this isn't in
* the past... */
if(loc_clock > (TRICKLE_TIMER_CLOCK_MAX >> 1)) {
loc_clock = 0; /* Interval ended in the past, schedule for in 0 */
PRINTF("trickle_timer doubling: Was in the past. Compensating\n");
}
ctimer_set(&tt->ct, loc_clock, double_interval, tt);
}
/*---------------------------------------------------------------------------*/
/* This is used as a ctimer callback, thus its argument must be void *. ptr is
* a pointer to the struct trickle_timer that fired */
static void
double_interval(void *ptr)
{
clock_time_t last_end;
/* 'cast' ptr to a struct trickle_timer */
loctt = (struct trickle_timer *)ptr;
loctt->c = 0;
PRINTF("trickle_timer doubling: at %lu, (was for %lu), ",
(unsigned long)clock_time(),
(unsigned long)TRICKLE_TIMER_INTERVAL_END(loctt));
/* Remember the previous interval's end (absolute time), before we double */
last_end = TRICKLE_TIMER_INTERVAL_END(loctt);
/* Double the interval if we have to */
if(loctt->i_cur <= TRICKLE_TIMER_INTERVAL_MAX(loctt) >> 1) {
/* If I <= Imax/2, we double */
loctt->i_cur <<= 1;
PRINTF("I << 1 = %lu\n", (unsigned long)loctt->i_cur);
} else {
/* We may have I > Imax/2 but I <> Imax, in which case we set to Imax
* This will happen when I didn't start as Imin (before the first reset) */
loctt->i_cur = TRICKLE_TIMER_INTERVAL_MAX(loctt);
PRINTF("I = Imax = %lu\n", (unsigned long)loctt->i_cur);
}
/* Random t in [I/2, I) */
loc_clock = get_t(loctt->i_cur);
PRINTF("trickle_timer doubling: t=%lu\n", (unsigned long)loc_clock);
#if TRICKLE_TIMER_COMPENSATE_DRIFT
/* Schedule for t ticks after the previous interval's end, not after now. If
* that is in the past, schedule in 0 */
loc_clock = (last_end + loc_clock) - clock_time();
PRINTF("trickle_timer doubling: at %lu, in %ld ticks\n",
(unsigned long)clock_time(), (signed long)loc_clock);
if(loc_clock > (TRICKLE_TIMER_CLOCK_MAX >> 1)) {
/* Oops, that's in the past */
loc_clock = 0;
PRINTF("trickle_timer doubling: Was in the past. Compensating\n");
}
ctimer_set(&loctt->ct, loc_clock, fire, loctt);
/* Store the actual interval start (absolute time), we need it later.
* We pretend that it started at the same time when the last one ended */
loctt->i_start = last_end;
#else
/* Assumed that the previous interval's end is 'now' and schedule in t ticks
* after 'now', ignoring potential offsets */
ctimer_set(&loctt->ct, loc_clock, fire, loctt);
/* Store the actual interval start (absolute time), we need it later */
loctt->i_start = loctt->ct.etimer.timer.start;
#endif
PRINTF("trickle_timer doubling: Last end %lu, new end %lu, for %lu, I=%lu\n",
(unsigned long)last_end,
(unsigned long)TRICKLE_TIMER_INTERVAL_END(loctt),
(unsigned long)(loctt->ct.etimer.timer.start +
loctt->ct.etimer.timer.interval),
(unsigned long)(loctt->i_cur));
}
/*---------------------------------------------------------------------------*/
/* Called by the ctimer module at time t within the current interval. ptr is
* a pointer to the struct trickle_timer of interest */
static void
fire(void *ptr)
{
/* 'cast' c to a struct trickle_timer */
loctt = (struct trickle_timer *)ptr;
PRINTF("trickle_timer fire: at %lu (was for %lu)\n",
(unsigned long)clock_time(),
(unsigned long)(loctt->ct.etimer.timer.start +
loctt->ct.etimer.timer.interval));
if(loctt->cb) {
/*
* Call the protocol's TX callback, with the suppression status as an
* argument.
*/
PRINTF("trickle_timer fire: Suppression Status %u (%u < %u)\n",
TRICKLE_TIMER_PROTO_TX_ALLOW(loctt), loctt->c, loctt->k);
loctt->cb(loctt->cb_arg, TRICKLE_TIMER_PROTO_TX_ALLOW(loctt));
}
schedule_for_end(loctt);
}
/*---------------------------------------------------------------------------*/
/* New trickle interval, either due to a newly set trickle timer or due to an
* inconsistency. Schedule 'fire' to be called in t ticks. */
static void
new_interval(struct trickle_timer *tt)
{
tt->c = 0;
/* Random t in [I/2, I) */
loc_clock = get_t(tt->i_cur);
ctimer_set(&tt->ct, loc_clock, fire, tt);
/* Store the actual interval start (absolute time), we need it later */
tt->i_start = tt->ct.etimer.timer.start;
PRINTF("trickle_timer new interval: at %lu, ends %lu, ",
(unsigned long)clock_time(),
(unsigned long)TRICKLE_TIMER_INTERVAL_END(tt));
PRINTF("t=%lu, I=%lu\n", (unsigned long)loc_clock, (unsigned long)tt->i_cur);
}
/*---------------------------------------------------------------------------*/
/* Functions to be called by the protocol implementation */
/*---------------------------------------------------------------------------*/
void
trickle_timer_consistency(struct trickle_timer *tt)
{
if(tt->c < 0xFF) {
tt->c++;
}
PRINTF("trickle_timer consistency: c=%u\n", tt->c);
}
/*---------------------------------------------------------------------------*/
void
trickle_timer_inconsistency(struct trickle_timer *tt)
{
/* "If I is equal to Imin when Trickle hears an "inconsistent" transmission,
* Trickle does nothing." */
if(tt->i_cur != tt->i_min) {
PRINTF("trickle_timer inconsistency\n");
tt->i_cur = tt->i_min;
new_interval(tt);
}
}
/*---------------------------------------------------------------------------*/
uint8_t
trickle_timer_config(struct trickle_timer *tt, clock_time_t i_min,
uint8_t i_max, uint8_t k)
{
#if TRICKLE_TIMER_ERROR_CHECKING
/*
* Although in theory Imin=1 is a valid value, it would break get_t() and
* doesn't make sense anyway. Thus Valid Imin values are in the range:
* 1 < Imin <= (TRICKLE_TIMER_CLOCK_MAX >> 1) + 1
*/
if(TRICKLE_TIMER_IMIN_IS_BAD(i_min)) {
PRINTF("trickle_timer config: Bad Imin value\n");
return TRICKLE_TIMER_ERROR;
}
if(tt == NULL || i_max == 0 || k == 0) {
PRINTF("trickle_timer config: Bad arguments\n");
return TRICKLE_TIMER_ERROR;
}
/*
* If clock_time_t is not wide enough to store Imin << Imax, we adjust Imax
*
* This means that 'we' are likely to have a different Imax than 'them'
* See RFC 6206, sec 6.3 for the consequences of this situation
*/
if(TRICKLE_TIMER_IPAIR_IS_BAD(i_min, i_max)) {
PRINTF("trickle_timer config: %lu << %u would exceed clock boundaries. ",
(unsigned long)i_min, i_max);
/* For this Imin, get the maximum sane Imax */
i_max = max_imax(i_min);
PRINTF("trickle_timer config: Using Imax=%u\n", i_max);
}
#endif
tt->i_min = i_min;
tt->i_max = i_max;
tt->i_max_abs = i_min << i_max;
tt->k = k;
PRINTF("trickle_timer config: Imin=%lu, Imax=%u, k=%u\n",
(unsigned long)tt->i_min, tt->i_max, tt->k);
return TRICKLE_TIMER_SUCCESS;
}
/*---------------------------------------------------------------------------*/
uint8_t
trickle_timer_set(struct trickle_timer *tt, trickle_timer_cb_t proto_cb,
void *ptr)
{
#if TRICKLE_TIMER_ERROR_CHECKING
/* Sanity checks */
if(tt == NULL || proto_cb == NULL) {
PRINTF("trickle_timer set: Bad arguments\n");
return TRICKLE_TIMER_ERROR;
}
#endif
tt->cb = proto_cb;
tt->cb_arg = ptr;
/* Random I in [Imin , Imax] */
tt->i_cur = tt->i_min +
(tt_rand() % (TRICKLE_TIMER_INTERVAL_MAX(tt) - tt->i_min + 1));
PRINTF("trickle_timer set: I=%lu in [%lu , %lu]\n", (unsigned long)tt->i_cur,
(unsigned long)tt->i_min,
(unsigned long)TRICKLE_TIMER_INTERVAL_MAX(tt));
new_interval(tt);
PRINTF("trickle_timer set: at %lu, ends %lu, t=%lu in [%lu , %lu)\n",
(unsigned long)tt->i_start,
(unsigned long)TRICKLE_TIMER_INTERVAL_END(tt),
(unsigned long)tt->ct.etimer.timer.interval,
(unsigned long)tt->i_cur >> 1, (unsigned long)tt->i_cur);
return TRICKLE_TIMER_SUCCESS;
}
/*---------------------------------------------------------------------------*/
/** @} */

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core/lib/trickle-timer.h Executable file
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/** \addtogroup lib
* @{ */
/**
* \defgroup trickle-timer Trickle timers
*
* This library implements timers which behave in accordance with RFC 6206
* "The Trickle Algorithm" (http://tools.ietf.org/html/rfc6206)
*
* Protocols wishing to use trickle timers, may use this library instead of
* implementing the trickle algorithm internally.
*
* The protocol implementation will declare one (or more) variable(s) of type
* struct ::trickle_timer and will then populate its fields by calling
* trickle_timer_config(). trickle_timer_set() will start the timer.
*
* When the timer reaches time t within the current trickle interval, the
* library will call a protocol-provided callback, which will signal to the
* protocol that it is time to TX (see algorithm step 4 in the RFC).
*
* The proto does not need to check the suppression conditions. This is done by
* the library and if TX must be suppressed, the callback won't be called at
* all.
*
* The library also provides functions to be called when the protocol hears a
* 'consistent' or 'inconsistent' message and when an 'external event' occurs
* (in this context, those terms have the exact same meaning as in the RFC).
*
* @{
*/
/**
* \file
* Trickle timer library header file.
*
* \author
* George Oikonomou - <oikonomou@users.sourceforge.net>
*/
/*
* Copyright (c) 2012, George Oikonomou - <oikonomou@users.sourceforge.net>
* 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 copyright holder 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 COPYRIGHT HOLDERS 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
* COPYRIGHT HOLDER 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.
*/
#ifndef __TRICKLE_TIMER_H__
#define __TRICKLE_TIMER_H__
#include "contiki-conf.h"
#include "sys/ctimer.h"
/*---------------------------------------------------------------------------*/
/* Trickle Timer Library Constants */
/*---------------------------------------------------------------------------*/
/**
* \name Trickle Timer Library: Constants
* @{
*/
/*---------------------------------------------------------------------------*/
/**
* \brief Set as value of k to disable suppression
*/
#define TRICKLE_TIMER_INFINITE_REDUNDANCY 0x00
#define TRICKLE_TIMER_ERROR 0
#define TRICKLE_TIMER_SUCCESS 1
/**
* \brief Use as the value of TRICKLE_TIMER_MAX_IMAX_WIDTH to enable the
* generic 'Find max Imax' routine
*/
#define TRICKLE_TIMER_MAX_IMAX_GENERIC 0
/**
* \brief Use as the value of TRICKLE_TIMER_MAX_IMAX_WIDTH to enable the 16-bit
* 'Find max Imax' routine
*/
#define TRICKLE_TIMER_MAX_IMAX_16_BIT 1
/**
* \brief Use as the value of TRICKLE_TIMER_MAX_IMAX_WIDTH to enable the 32-bit
* 'Find max Imax' routine
*/
#define TRICKLE_TIMER_MAX_IMAX_32_BIT 2
/**
* \brief Constants used as values for the \e suppress param of
* trickle_timer_cb_t
*/
#define TRICKLE_TIMER_TX_SUPPRESS 0
#define TRICKLE_TIMER_TX_OK 1
/** @} */
/*---------------------------------------------------------------------------*/
/**
* \brief Controls whether the library will try to compensate for time drifts
* caused by getting called later than scheduled.
*
* 1: Enabled (default). 0: Disabled
*
* To override the default, define TRICKLE_TIMER_CONF_COMPENSATE_DRIFT in
* contiki-conf.h
*
* Bear in mind that this controls the behaviour of the entire library (i.e.
* all trickle timers) and not of an individual timer
*/
#ifdef TRICKLE_TIMER_CONF_COMPENSATE_DRIFT
#define TRICKLE_TIMER_COMPENSATE_DRIFT TRICKLE_TIMER_CONF_COMPENSATE_DRIFT
#else
#define TRICKLE_TIMER_COMPENSATE_DRIFT 1
#endif
/*---------------------------------------------------------------------------*/
/**
* \brief Turns on support for 4-byte wide, unsigned random numbers
*
* We need this for platforms which have a 4-byte wide clock_time_t. For those
* platforms and if Imin << Imax is GT 0xFFFF, random_rand alone is not always
* enough to generate a correct t in [I/2, I). Specifically, we need wide
* randoms when I > 0x1FFFF.
*
* For platforms with a 2-byte wide clock_time_t, this can be defined as 0
* to reduce code footprint and increase speed.
*/
#ifdef TRICKLE_TIMER_CONF_WIDE_RAND
#define TRICKLE_TIMER_WIDE_RAND TRICKLE_TIMER_CONF_WIDE_RAND
#else
#define TRICKLE_TIMER_WIDE_RAND 1
#endif
/*---------------------------------------------------------------------------*/
/**
* \brief Selects a flavor for the 'Find maximum Imax' (max_imax) function.
*
* When configuring a new trickle timer, the library verifies that the (Imin ,
* Imax) pair will fit in the platform's clock_time_t boundaries. If this is
* not the case, Imax will be adjusted down. In order to achieve this, we use
* an internal function which is a slight variant of a standard 'Count Leading
* Zeros'.
*
* This functionality is disabled when ::TRICKLE_TIMER_ERROR_CHECKING is 0
*
* This define helps us generate, at the pre-processing stage, the desired
* version of this function. We start with a generic version by default. The
* platform's contiki-conf.h can change this to use the 16- or 32-bit specific
* flavor by defining TRICKLE_TIMER_CONF_MAX_IMAX_WIDTH.
*
* Depending on the toolchain, the generic variant may actually result in a
* smaller code size. Do your own experiments.
*
* TRICKLE_TIMER_MAX_IMAX_GENERIC (0): Generic function which will work
* regardless whether the platform uses a 16 or 32 bit wide clock type
*
* TRICKLE_TIMER_MAX_IMAX_16_BIT (1): You can select this in your
* contiki-conf.h if your platform's clock_time_t is 16 bits wide
*
* TRICKLE_TIMER_MAX_IMAX_32_BIT (2): You can select this in your
* contiki-conf.h if your platform's clock_time_t is 32 bits wide
*/
#ifdef TRICKLE_TIMER_CONF_MAX_IMAX_WIDTH
#define TRICKLE_TIMER_MAX_IMAX_WIDTH TRICKLE_TIMER_CONF_MAX_IMAX_WIDTH
#else
#define TRICKLE_TIMER_MAX_IMAX_WIDTH TRICKLE_TIMER_MAX_IMAX_GENERIC
#endif
/**
* \brief Enables/Disables error checking
*
* 1: Enabled (default). The library checks the validity of Imin and Imax
* 0: Disabled. All error checking is turned off. This reduces code size.
*/
#ifdef TRICKLE_TIMER_CONF_ERROR_CHECKING
#define TRICKLE_TIMER_ERROR_CHECKING TRICKLE_TIMER_CONF_ERROR_CHECKING
#else
#define TRICKLE_TIMER_ERROR_CHECKING 1
#endif
/*---------------------------------------------------------------------------*/
/* Trickle Timer Library Macros */
/*---------------------------------------------------------------------------*/
/**
* \name Trickle Timer Library: Macros
* @{
*/
/**
* \brief cross-platform method to get the maximum clock_time_t value
*/
#define TRICKLE_TIMER_CLOCK_MAX ((clock_time_t)~0)
/**
* \brief Checks if the trickle timer's suppression feature is enabled
*
* \param tt A pointer to a ::trickle_timer structure
*
* \retval non-zero Suppression is enabled
* \retval 0 Suppression is disabled
*/
#define TRICKLE_TIMER_SUPPRESSION_ENABLED(tt) \
((tt)->k != TRICKLE_TIMER_INFINITE_REDUNDANCY)
/**
* \brief Checks if the trickle timer's suppression feature is disabled
*
* \param tt A pointer to a ::trickle_timer structure
*
* \retval non-zero Suppression is disabled
* \retval 0 Suppression is enabled
*/
#define TRICKLE_TIMER_SUPPRESSION_DISABLED(tt) \
((tt)->k == TRICKLE_TIMER_INFINITE_REDUNDANCY)
/**
* \brief Determines whether the protocol must go ahead with a transmission
*
* \param tt A pointer to a ::trickle_timer structure
*
* \retval non-zero Go ahead with TX
* \retval 0 Suppress
*/
#define TRICKLE_TIMER_PROTO_TX_ALLOW(tt) \
(TRICKLE_TIMER_SUPPRESSION_DISABLED(tt) || ((tt)->c < (tt)->k))
/**
* \brief Determines whether the protocol must suppress a transmission
*
* \param tt A pointer to a ::trickle_timer structure
*
* \retval non-zero Suppress
* \retval 0 Go ahead with TX
*/
#define TRICKLE_TIMER_PROTO_TX_SUPPRESS(tt) \
(TRICKLE_TIMER_SUPPRESSION_ENABLED(tt) && ((tt)->c >= (tt)->k))
/**
* \brief Returns a timer's maximum interval size (Imin << Imax) as a number of
* clock ticks
*
* \param tt A pointer to a ::trickle_timer structure
*
* \return Maximum trickle interval length in clock ticks
*/
#define TRICKLE_TIMER_INTERVAL_MAX(tt) ((tt)->i_max_abs)
/**
* \brief Returns the current trickle interval's end (absolute time in ticks)
*
* \param tt A pointer to a ::trickle_timer structure
*
* \return The absolute number of clock ticks when the current trickle interval
* will expire
*/
#define TRICKLE_TIMER_INTERVAL_END(tt) ((tt)->i_start + (tt)->i_cur)
/**
* \brief Checks whether an Imin value is suitable considering the various
* restrictions imposed by our platform's clock as well as by the library itself
*
* \param imin An Imin value in clock ticks
*
* \retval 1 The Imin value is valid
* \retval 0 The Imin value is invalid
*/
#define TRICKLE_TIMER_IMIN_IS_OK(imin) \
((imin > 1) && (i_min <= (TRICKLE_TIMER_CLOCK_MAX >> 1)))
/**
* \brief Checks whether an Imin value is invalid considering the various
* restrictions imposed by our platform's clock as well as by the library itself
*
* \param imin An Imin value in clock ticks
*
* \retval 1 The Imin value is invalid
* \retval 0 The Imin value is valid
*/
#define TRICKLE_TIMER_IMIN_IS_BAD(imin) \
((imin < 2) || (i_min > (TRICKLE_TIMER_CLOCK_MAX >> 1)))
/**
* \brief Checks whether Imin << Imax is unsuitable considering the boundaries
* of our platform's clock_time_t
*
* \param i_min Imin value
* \param i_max Maximum number of doublings
*
* \retval non-zero The pair would exceed clock boundaries
* \retval 0 The pair is suitable for the platform
*
* Timers scheduled far in the future can be perceived as being scheduled in
* the past.
* Thus, we limit Imin << Imax to be LEQ(TRICKLE_TIMER_CLOCK_MAX >> 1) + 1
*/
#define TRICKLE_TIMER_IPAIR_IS_BAD(i_min, i_max) \
((TRICKLE_TIMER_CLOCK_MAX >> (i_max + 1)) < i_min - 1)
/** @} */
/*---------------------------------------------------------------------------*/
/* Trickle Timer Library Data Representation */
/*---------------------------------------------------------------------------*/
/**
* \name Trickle Timer Library: Data Representation
* @{
*/
/**
* \brief typedef for a callback function to be defined in the protocol's
* implementation.
*
* Those callbaks are stored as a function pointer inside a ::trickle_timer
* structure and are called by the library at time t within the current trickle
* interval.
*
* Some protocols may rely on multiple trickle timers. For this reason, this
* function's argument will be an opaque pointer, aiming to help the protocol
* determine which timer triggered the call.
*
* The \e suppress argument is used so that the library can signal the protocol
* whether it should TX or suppress
*/
typedef void (* trickle_timer_cb_t)(void *ptr, uint8_t suppress);
/**
* \struct trickle_timer
*
* A trickle timer.
*
* This structure is used for declaring a trickle timer. In order for the timer
* to start running, the protocol must first populate the structure's fields
* by calling trickle_timer_set(). Protocol implementations must NOT modify the
* contents of this structure directly.
*
* Protocol developers must also be careful to specify the values of Imin and
* Imax in such a way that the maximum interval size does not exceed the
* boundaries of clock_time_t
*/
struct trickle_timer {
clock_time_t i_min; /**< Imin: Clock ticks */
clock_time_t i_cur; /**< I: Current interval in clock_ticks */
clock_time_t i_start; /**< Start of this interval (absolute clock_time) */
clock_time_t i_max_abs; /**< Maximum interval size in clock ticks (and not in
number of doublings). This is a cached value of
Imin << Imax used internally, so that we can
have direct access to the maximum interval size
without having to calculate it all the time */
struct ctimer ct; /**< A \ref ctimer used internally */
trickle_timer_cb_t cb; /**< Protocol's own callback, invoked at time t
within the current interval */
void *cb_arg; /**< Opaque pointer to be used as the argument of the
protocol's callback */
uint8_t i_max; /**< Imax: Max number of doublings */
uint8_t k; /**< k: Redundancy Constant */
uint8_t c; /**< c: Consistency Counter */
};
/** @} */
/*---------------------------------------------------------------------------*/
/* Trickle Timer Library Functions */
/*---------------------------------------------------------------------------*/
/**
* \name Trickle Timer Library: Functions called by protocol implementations
* @{
*/
/**
* \brief Configure a trickle timer
* \param tt A pointer to a ::trickle_timer structure
* \param i_min The timer's Imin configuration parameter, in units of
* clock_time_t
* \param i_max The timer's Imax configuration parameter (maximum number of
* doublings), specified as number of doublings
* \param k The timer's K (redundancy constant). If the value of K
* equals #TRICKLE_TIMER_INFINITE_REDUNDANCY, message
* suppression will be disabled
* \retval 0 Error (Bad argument)
* \retval non-zero Success.
*
* This function is used to set the initial configuration for a trickle timer.
* A trickle timer MUST be configured before the protocol calls
* trickle_timer_set().
*
* If Imin<<Imax would exceed the platform's clock_time_t boundaries, this
* function adjusts Imax to the maximum permitted value for the provided Imin.
* This means that in a network with heterogenous hardware, 'we' are likely to
* have a different Imax than 'some of them'. See RFC 6206, sec 6.3 for the
* consequences of this situation
*/
uint8_t trickle_timer_config(struct trickle_timer *tt, clock_time_t i_min,
uint8_t i_max, uint8_t k);
/**
* \brief Start a previously configured trickle timer
* \param tt A pointer to a ::trickle_timer structure
* \param proto_cb A pointer to a callback function, which will be invoked at
* at time t within the current trickle interval
* \param ptr An opaque pointer which will be passed as the argument to
* proto_cb when the timer fires.
* \retval 0 Error (tt was null or the timer was not configured properly)
* \retval non-zero Success.
*
* This function is used to set a trickle timer. The protocol implementation
* must use this function ONLY to initialise a new trickle timer and NOT to
* reset it as a result of external events or inconsistencies.
*
* The protocol implementation must configure the trickle timer by calling
* trickle_timer_config() before calling this function.
*/
uint8_t trickle_timer_set(struct trickle_timer *tt,
trickle_timer_cb_t proto_cb, void *ptr);
/**
* \brief Stop a running trickle timer.
* \param tt A pointer to a ::trickle_timer structure
*
* This function stops a running trickle timer that was previously started with
* trickle_timer_start(). After this function has been called, the trickle
* timer will no longer call the protocol's callback and its interval will not
* double any more. In order to resume the trickle timer, the user application
* must call trickle_timer_set().
*
* The protocol implementation must NOT use trickle_timer_stop(), _set() cycles
* to reset a timer manually. Instead, in response to events or inconsistencies,
* the corresponding functions must be used
*/
#define trickle_timer_stop(tt) ctimer_stop((tt)->ct)
/**
* \brief To be called by the protocol when it hears a consistent
* transmission
* \param tt A pointer to a ::trickle_timer structure
*
* When the trickle-based protocol hears a consistent transmission it must call
* this function to increment trickle's consistency counter, which is later
* used to determine whether the protocol must suppress or go ahead with its
* own transmissions.
*
* As the trickle timer library implementation may change in the future to
* perform further tasks upon reception of a consistent transmission, the
* protocol's implementation MUST use this call to increment the consistency
* counter instead of directly writing to the structure's field.
*/
void trickle_timer_consistency(struct trickle_timer *tt);
/**
* \brief To be called by the protocol when it hears an inconsistent
* transmission
* \param tt A pointer to a ::trickle_timer structure
*
* When the protocol hears an inconsistent transmission, it must call this
* function to notify the library that the timer must be reset.
*
* Before resetting the timer, the library will perform a set of checks.
* Therefore, it is important that the protocol calls this function instead of
* trying to reset the timer by itself.
*/
void trickle_timer_inconsistency(struct trickle_timer *tt);
/**
* \brief To be called by the protocol when an external event occurs that
* should trigger a timer reset
* \param tt A pointer to a ::trickle_timer structure
*
* When an external event occurs that should result in a timer reset, the
* protocol implementation must call this function to notify the library.
*
* Before resetting the timer, the library will perform a set of checks.
* Therefore, it is important that the protocol calls this function instead of
* trying to reset the timer by itself.
*/
#define trickle_timer_reset_event(tt) trickle_timer_inconsistency(tt)
/** @} */
#endif /* __TRICKLE_TIMER_H__ */
/** @} */
/** @} */