osd-contiki/core/net/rpl/rpl-of0.c

124 lines
3.7 KiB
C

/**
* \addtogroup uip6
* @{
*/
/*
* 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.
*/
/**
* \file
* An implementation of RPL's objective function 0.
*
* \author Joakim Eriksson <joakime@sics.se>, Nicolas Tsiftes <nvt@sics.se>
*/
#include "net/rpl/rpl-private.h"
#define DEBUG DEBUG_ANNOTATE
#include "net/uip-debug.h"
#include "net/neighbor-info.h"
static void reset(rpl_dag_t *);
static rpl_parent_t *best_parent(rpl_parent_t *, rpl_parent_t *);
static rpl_rank_t calculate_rank(rpl_parent_t *, rpl_rank_t);
rpl_of_t rpl_of0 = {
reset,
NULL,
best_parent,
calculate_rank,
0
};
#define DEFAULT_RANK_INCREMENT DEFAULT_MIN_HOPRANKINC
#define MIN_DIFFERENCE (ETX_DIVISOR + ETX_DIVISOR / 2)
static void
reset(rpl_dag_t *dag)
{
PRINTF("RPL: Resetting OF0\n");
}
static rpl_rank_t
calculate_rank(rpl_parent_t *p, rpl_rank_t base_rank)
{
rpl_rank_t increment;
if(base_rank == 0) {
if(p == NULL) {
return INFINITE_RANK;
}
base_rank = p->rank;
}
increment = p != NULL ? p->dag->min_hoprankinc : DEFAULT_RANK_INCREMENT;
if((rpl_rank_t)(base_rank + increment) < base_rank) {
PRINTF("RPL: OF0 rank %d incremented to infinite rank due to wrapping\n",
base_rank);
return INFINITE_RANK;
}
return base_rank + increment;
}
static rpl_parent_t *
best_parent(rpl_parent_t *p1, rpl_parent_t *p2)
{
rpl_rank_t r1, r2;
rpl_dag_t *dag;
PRINTF("RPL: Comparing parent ");
PRINT6ADDR(&p1->addr);
PRINTF(" (confidence %d, rank %d) with parent ",
p1->etx, p1->rank);
PRINT6ADDR(&p2->addr);
PRINTF(" (confidence %d, rank %d)\n",
p2->etx, p2->rank);
r1 = DAG_RANK(p1->rank, (rpl_dag_t *)p1->dag) * ETX_DIVISOR + p1->etx;
r2 = DAG_RANK(p2->rank, (rpl_dag_t *)p1->dag) * ETX_DIVISOR + p2->etx;
/* Compare two parents by looking both and their rank and at the ETX
for that parent. We choose the parent that has the most
favourable combination. */
dag = (rpl_dag_t *)p1->dag; /* Both parents must be in the same DAG. */
if(r1 < r2 + MIN_DIFFERENCE &&
r1 > r2 - MIN_DIFFERENCE) {
return dag->preferred_parent;
} else if(r1 < r2) {
return p1;
} else {
return p2;
}
}