43b5425493
Fixed a wrapping problem in the ETX EWMA calculation. Corrected the multiplier of the link metric, and simplified the configuration so that the user does not need to specify the multiplier.
266 lines
7.6 KiB
C
266 lines
7.6 KiB
C
/**
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* \addtogroup uip6
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* @{
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*/
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/*
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* Copyright (c) 2010, 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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*/
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/**
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* \file
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* The Minimum Rank with Hysteresis Objective Function (MRHOF)
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*
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* This implementation uses the estimated number of
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* transmissions (ETX) as the additive routing metric,
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* and also provides stubs for the energy metric.
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*
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* \author Joakim Eriksson <joakime@sics.se>, Nicolas Tsiftes <nvt@sics.se>
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*/
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#include "net/rpl/rpl-private.h"
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#include "net/nbr-table.h"
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#define DEBUG DEBUG_NONE
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#include "net/uip-debug.h"
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static void reset(rpl_dag_t *);
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static void neighbor_link_callback(rpl_parent_t *, int, int);
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static rpl_parent_t *best_parent(rpl_parent_t *, rpl_parent_t *);
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static rpl_dag_t *best_dag(rpl_dag_t *, rpl_dag_t *);
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static rpl_rank_t calculate_rank(rpl_parent_t *, rpl_rank_t);
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static void update_metric_container(rpl_instance_t *);
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rpl_of_t rpl_mrhof = {
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reset,
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neighbor_link_callback,
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best_parent,
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best_dag,
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calculate_rank,
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update_metric_container,
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1
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};
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/* Constants for the ETX moving average */
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#define ETX_SCALE 100
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#define ETX_ALPHA 90
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/* Reject parents that have a higher link metric than the following. */
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#define MAX_LINK_METRIC 10
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/* Reject parents that have a higher path cost than the following. */
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#define MAX_PATH_COST 100
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/*
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* The rank must differ more than 1/PARENT_SWITCH_THRESHOLD_DIV in order
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* to switch preferred parent.
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*/
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#define PARENT_SWITCH_THRESHOLD_DIV 2
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typedef uint16_t rpl_path_metric_t;
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static rpl_path_metric_t
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calculate_path_metric(rpl_parent_t *p)
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{
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if(p == NULL) {
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return MAX_PATH_COST * RPL_DAG_MC_ETX_DIVISOR;
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}
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#if RPL_DAG_MC == RPL_DAG_MC_NONE
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return p->rank + (uint16_t)p->link_metric;
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#elif RPL_DAG_MC == RPL_DAG_MC_ETX
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return p->mc.obj.etx + (uint16_t)p->link_metric;
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#elif RPL_DAG_MC == RPL_DAG_MC_ENERGY
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return p->mc.obj.energy.energy_est + (uint16_t)p->link_metric;
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#else
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#error "Unsupported RPL_DAG_MC configured. See rpl.h."
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#endif /* RPL_DAG_MC */
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}
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static void
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reset(rpl_dag_t *sag)
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{
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PRINTF("RPL: Reset MRHOF\n");
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}
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static void
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neighbor_link_callback(rpl_parent_t *p, int status, int numtx)
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{
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uint16_t recorded_etx = p->link_metric;
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uint16_t packet_etx = numtx * RPL_DAG_MC_ETX_DIVISOR;
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uint16_t new_etx;
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/* Do not penalize the ETX when collisions or transmission errors occur. */
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if(status == MAC_TX_OK || status == MAC_TX_NOACK) {
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if(status == MAC_TX_NOACK) {
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packet_etx = MAX_LINK_METRIC * RPL_DAG_MC_ETX_DIVISOR;
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}
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new_etx = ((uint32_t)recorded_etx * ETX_ALPHA +
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(uint32_t)packet_etx * (ETX_SCALE - ETX_ALPHA)) / ETX_SCALE;
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PRINTF("RPL: ETX changed from %u to %u (packet ETX = %u)\n",
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(unsigned)(recorded_etx / RPL_DAG_MC_ETX_DIVISOR),
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(unsigned)(new_etx / RPL_DAG_MC_ETX_DIVISOR),
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(unsigned)(packet_etx / RPL_DAG_MC_ETX_DIVISOR));
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p->link_metric = new_etx;
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}
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}
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static rpl_rank_t
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calculate_rank(rpl_parent_t *p, rpl_rank_t base_rank)
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{
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rpl_rank_t new_rank;
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rpl_rank_t rank_increase;
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if(p == NULL) {
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if(base_rank == 0) {
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return INFINITE_RANK;
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}
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rank_increase = RPL_INIT_LINK_METRIC * RPL_DAG_MC_ETX_DIVISOR;
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} else {
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rank_increase = p->link_metric;
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if(base_rank == 0) {
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base_rank = p->rank;
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}
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}
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if(INFINITE_RANK - base_rank < rank_increase) {
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/* Reached the maximum rank. */
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new_rank = INFINITE_RANK;
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} else {
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/* Calculate the rank based on the new rank information from DIO or
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stored otherwise. */
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new_rank = base_rank + rank_increase;
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}
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return new_rank;
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}
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static rpl_dag_t *
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best_dag(rpl_dag_t *d1, rpl_dag_t *d2)
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{
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if(d1->grounded != d2->grounded) {
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return d1->grounded ? d1 : d2;
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}
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if(d1->preference != d2->preference) {
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return d1->preference > d2->preference ? d1 : d2;
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}
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return d1->rank < d2->rank ? d1 : d2;
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}
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static rpl_parent_t *
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best_parent(rpl_parent_t *p1, rpl_parent_t *p2)
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{
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rpl_dag_t *dag;
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rpl_path_metric_t min_diff;
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rpl_path_metric_t p1_metric;
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rpl_path_metric_t p2_metric;
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dag = p1->dag; /* Both parents are in the same DAG. */
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min_diff = RPL_DAG_MC_ETX_DIVISOR /
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PARENT_SWITCH_THRESHOLD_DIV;
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p1_metric = calculate_path_metric(p1);
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p2_metric = calculate_path_metric(p2);
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/* Maintain stability of the preferred parent in case of similar ranks. */
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if(p1 == dag->preferred_parent || p2 == dag->preferred_parent) {
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if(p1_metric < p2_metric + min_diff &&
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p1_metric > p2_metric - min_diff) {
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PRINTF("RPL: MRHOF hysteresis: %u <= %u <= %u\n",
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p2_metric - min_diff,
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p1_metric,
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p2_metric + min_diff);
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return dag->preferred_parent;
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}
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}
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return p1_metric < p2_metric ? p1 : p2;
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}
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#if RPL_DAG_MC == RPL_DAG_MC_NONE
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static void
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update_metric_container(rpl_instance_t *instance)
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{
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instance->mc.type = RPL_DAG_MC;
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}
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#else
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static void
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update_metric_container(rpl_instance_t *instance)
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{
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rpl_path_metric_t path_metric;
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rpl_dag_t *dag;
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#if RPL_DAG_MC == RPL_DAG_MC_ENERGY
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uint8_t type;
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#endif
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instance->mc.type = RPL_DAG_MC;
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instance->mc.flags = RPL_DAG_MC_FLAG_P;
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instance->mc.aggr = RPL_DAG_MC_AGGR_ADDITIVE;
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instance->mc.prec = 0;
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dag = instance->current_dag;
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if (!dag->joined) {
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PRINTF("RPL: Cannot update the metric container when not joined\n");
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return;
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}
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if(dag->rank == ROOT_RANK(instance)) {
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path_metric = 0;
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} else {
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path_metric = calculate_path_metric(dag->preferred_parent);
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}
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#if RPL_DAG_MC == RPL_DAG_MC_ETX
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instance->mc.length = sizeof(instance->mc.obj.etx);
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instance->mc.obj.etx = path_metric;
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PRINTF("RPL: My path ETX to the root is %u.%u\n",
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instance->mc.obj.etx / RPL_DAG_MC_ETX_DIVISOR,
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(instance->mc.obj.etx % RPL_DAG_MC_ETX_DIVISOR * 100) /
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RPL_DAG_MC_ETX_DIVISOR);
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#elif RPL_DAG_MC == RPL_DAG_MC_ENERGY
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instance->mc.length = sizeof(instance->mc.obj.energy);
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if(dag->rank == ROOT_RANK(instance)) {
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type = RPL_DAG_MC_ENERGY_TYPE_MAINS;
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} else {
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type = RPL_DAG_MC_ENERGY_TYPE_BATTERY;
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}
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instance->mc.obj.energy.flags = type << RPL_DAG_MC_ENERGY_TYPE;
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instance->mc.obj.energy.energy_est = path_metric;
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#endif /* RPL_DAG_MC == RPL_DAG_MC_ETX */
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}
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#endif /* RPL_DAG_MC == RPL_DAG_MC_NONE */
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