nes-proj/os/net/rpl-lite/rpl-of0.c

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/*
* Copyright (c) 2010, 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.
*
*/
/**
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* \addtogroup rpl-lite
* @{
*
* \file
* An implementation of RPL's objective function 0, RFC6552
*
* \author Joakim Eriksson <joakime@sics.se>, Nicolas Tsiftes <nvt@sics.se>
* Simon Duquennoy <simon.duquennoy@inria.fr>
*/
#include "net/rpl-lite/rpl.h"
#include "net/nbr-table.h"
#include "net/link-stats.h"
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/* Log configuration */
#include "sys/log.h"
#define LOG_MODULE "RPL"
#define LOG_LEVEL LOG_LEVEL_RPL
/* Constants from RFC6552. We use the default values. */
#define RANK_STRETCH 0 /* Must be in the range [0;5] */
#define RANK_FACTOR 1 /* Must be in the range [1;4] */
#define MIN_STEP_OF_RANK 1
#define MAX_STEP_OF_RANK 9
/* OF0 computes rank increase as follows:
* rank_increase = (RANK_FACTOR * STEP_OF_RANK + RANK_STRETCH) * min_hop_rank_increase
* STEP_OF_RANK is an implementation-specific scalar value in the range [1;9].
* RFC6552 provides a default value of 3 but recommends to use a dynamic link metric
* such as ETX.
* */
#define RPL_OF0_FIXED_SR 0
#define RPL_OF0_ETX_BASED_SR 1
/* Select RPL_OF0_FIXED_SR or RPL_OF0_ETX_BASED_SR */
#ifdef RPL_OF0_CONF_SR
#define RPL_OF0_SR RPL_OF0_CONF_SR
#else /* RPL_OF0_CONF_SR */
#define RPL_OF0_SR RPL_OF0_ETX_BASED_SR
#endif /* RPL_OF0_CONF_SR */
#if RPL_OF0_FIXED_SR
#define STEP_OF_RANK(nbr) (3)
#endif /* RPL_OF0_FIXED_SR */
#if RPL_OF0_ETX_BASED_SR
/* Numbers suggested by P. Thubert for in the 6TiSCH WG. Anything that maps ETX to
* a step between 1 and 9 works. */
#define STEP_OF_RANK(nbr) (((3 * nbr_link_metric(nbr)) / LINK_STATS_ETX_DIVISOR) - 2)
#endif /* RPL_OF0_ETX_BASED_SR */
/*---------------------------------------------------------------------------*/
static void
reset(void)
{
LOG_INFO("reset OF0\n");
}
/*---------------------------------------------------------------------------*/
static uint16_t
nbr_link_metric(rpl_nbr_t *nbr)
{
/* OF0 operates without metric container; the only metric we have is ETX */
const struct link_stats *stats = rpl_neighbor_get_link_stats(nbr);
return stats != NULL ? stats->etx : 0xffff;
}
/*---------------------------------------------------------------------------*/
static uint16_t
nbr_rank_increase(rpl_nbr_t *nbr)
{
uint16_t min_hoprankinc;
if(nbr == NULL) {
return RPL_INFINITE_RANK;
}
min_hoprankinc = curr_instance.min_hoprankinc;
return (RANK_FACTOR * STEP_OF_RANK(nbr) + RANK_STRETCH) * min_hoprankinc;
}
/*---------------------------------------------------------------------------*/
static uint16_t
nbr_path_cost(rpl_nbr_t *nbr)
{
if(nbr == NULL) {
return 0xffff;
}
/* path cost upper bound: 0xffff */
return MIN((uint32_t)nbr->rank + nbr_link_metric(nbr), 0xffff);
}
/*---------------------------------------------------------------------------*/
static rpl_rank_t
rank_via_nbr(rpl_nbr_t *nbr)
{
if(nbr == NULL) {
return RPL_INFINITE_RANK;
} else {
return MIN((uint32_t)nbr->rank + nbr_rank_increase(nbr), RPL_INFINITE_RANK);
}
}
/*---------------------------------------------------------------------------*/
static int
nbr_has_usable_link(rpl_nbr_t *nbr)
{
return 1;
}
/*---------------------------------------------------------------------------*/
static int
nbr_is_acceptable_parent(rpl_nbr_t *nbr)
{
return STEP_OF_RANK(nbr) >= MIN_STEP_OF_RANK
&& STEP_OF_RANK(nbr) <= MAX_STEP_OF_RANK;
}
/*---------------------------------------------------------------------------*/
static rpl_nbr_t *
best_parent(rpl_nbr_t *nbr1, rpl_nbr_t *nbr2)
{
uint16_t nbr1_cost;
uint16_t nbr2_cost;
int nbr1_is_acceptable;
int nbr2_is_acceptable;
nbr1_is_acceptable = nbr1 != NULL && nbr_is_acceptable_parent(nbr1);
nbr2_is_acceptable = nbr2 != NULL && nbr_is_acceptable_parent(nbr2);
if(!nbr1_is_acceptable) {
return nbr2_is_acceptable ? nbr2 : NULL;
}
if(!nbr2_is_acceptable) {
return nbr1_is_acceptable ? nbr1 : NULL;
}
nbr1_cost = nbr_path_cost(nbr1);
nbr2_cost = nbr_path_cost(nbr2);
/* Paths costs coarse-grained (multiple of min_hoprankinc), we operate without hysteresis */
if(nbr1_cost != nbr2_cost) {
/* Pick nbr with lowest path cost */
return nbr1_cost < nbr2_cost ? nbr1 : nbr2;
} else {
/* We have a tie! */
/* Stik to current preferred parent if possible */
if(nbr1 == curr_instance.dag.preferred_parent || nbr2 == curr_instance.dag.preferred_parent) {
return curr_instance.dag.preferred_parent;
}
/* None of the nodes is the current preferred parent,
* choose nbr with best link metric */
return nbr_link_metric(nbr1) < nbr_link_metric(nbr2) ? nbr1 : nbr2;
}
}
/*---------------------------------------------------------------------------*/
static void
update_metric_container(void)
{
curr_instance.mc.type = RPL_DAG_MC_NONE;
}
/*---------------------------------------------------------------------------*/
rpl_of_t rpl_of0 = {
reset,
nbr_link_metric,
nbr_has_usable_link,
nbr_is_acceptable_parent,
nbr_path_cost,
rank_via_nbr,
best_parent,
update_metric_container,
RPL_OCP_OF0
};
/** @}*/