124 lines
3.7 KiB
C
124 lines
3.7 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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* \file
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* An implementation of RPL's objective function 0.
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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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#define DEBUG DEBUG_ANNOTATE
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#include "net/uip-debug.h"
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#include "net/neighbor-info.h"
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static void reset(rpl_dag_t *);
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static rpl_parent_t *best_parent(rpl_parent_t *, rpl_parent_t *);
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static rpl_rank_t calculate_rank(rpl_parent_t *, rpl_rank_t);
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rpl_of_t rpl_of0 = {
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reset,
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NULL,
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best_parent,
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calculate_rank,
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0
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};
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#define DEFAULT_RANK_INCREMENT DEFAULT_MIN_HOPRANKINC
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#define MIN_DIFFERENCE (ETX_DIVISOR + ETX_DIVISOR / 2)
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static void
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reset(rpl_dag_t *dag)
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{
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PRINTF("RPL: Resetting OF0\n");
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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 increment;
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if(base_rank == 0) {
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if(p == NULL) {
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return INFINITE_RANK;
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}
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base_rank = p->rank;
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}
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increment = p != NULL ? p->dag->min_hoprankinc : DEFAULT_RANK_INCREMENT;
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if((rpl_rank_t)(base_rank + increment) < base_rank) {
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PRINTF("RPL: OF0 rank %d incremented to infinite rank due to wrapping\n",
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base_rank);
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return INFINITE_RANK;
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}
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return base_rank + increment;
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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_rank_t r1, r2;
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rpl_dag_t *dag;
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PRINTF("RPL: Comparing parent ");
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PRINT6ADDR(&p1->addr);
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PRINTF(" (confidence %d, rank %d) with parent ",
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p1->etx, p1->rank);
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PRINT6ADDR(&p2->addr);
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PRINTF(" (confidence %d, rank %d)\n",
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p2->etx, p2->rank);
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r1 = DAG_RANK(p1->rank, (rpl_dag_t *)p1->dag) * ETX_DIVISOR + p1->etx;
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r2 = DAG_RANK(p2->rank, (rpl_dag_t *)p1->dag) * ETX_DIVISOR + p2->etx;
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/* Compare two parents by looking both and their rank and at the ETX
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for that parent. We choose the parent that has the most
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favourable combination. */
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dag = (rpl_dag_t *)p1->dag; /* Both parents must be in the same DAG. */
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if(r1 < r2 + MIN_DIFFERENCE &&
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r1 > r2 - MIN_DIFFERENCE) {
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return dag->preferred_parent;
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} else if(r1 < r2) {
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return p1;
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} else {
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return p2;
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}
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}
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