nes-proj/core/net/rime/collect-link-estimate.c

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/**
* \addtogroup rimelinkestimate
* @{
*/
/*
* 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.
*
* $Id: collect-link-estimate.c,v 1.5 2010/10/11 23:34:02 adamdunkels Exp $
*/
/**
* \file
* Implementation of Collect link estimate based on ETX
* \author
* Adam Dunkels <adam@sics.se>
*/
#include "net/rime/collect.h"
#include "net/rime/collect-link-estimate.h"
/* This defines the window used by the ETX computation when computing
the ETX. It cannot be larger than
COLLECT_LINK_ESTIMATE_HISTORY_SIZE, which is defined in
collect-link-estimate.h. */
#define ETX_HISTORY_WINDOW 8
#define INITIAL_LINK_ESTIMATE 16
#define DEBUG 0
#if DEBUG
#include <stdio.h>
#define PRINTF(...) printf(__VA_ARGS__)
#else
#define PRINTF(...)
#endif
/*---------------------------------------------------------------------------*/
static void
set_all_estimates(struct collect_link_estimate *le, uint16_t value)
{
int i;
for(i = 0; i < ETX_HISTORY_WINDOW; i++) {
le->history[i] = value;
}
}
/*---------------------------------------------------------------------------*/
void
collect_link_estimate_new(struct collect_link_estimate *le)
{
/* Start with a conservative / pessimistic estimate of link quality
for new links. */
set_all_estimates(le, 0/*INITIAL_LINK_ESTIMATE*/);
le->historyptr = 0;
le->num_estimates = 0;
}
/*---------------------------------------------------------------------------*/
void
collect_link_estimate_update_tx(struct collect_link_estimate *le, uint8_t tx)
{
if(tx == 0) {
/* printf("ERROR tx == 0\n");*/
return;
}
if(le != NULL) {
/* if(le->num_estimates == 0) {
set_all_estimates(le, tx);
} else*/ {
le->history[le->historyptr] = tx;
le->historyptr = (le->historyptr + 1) % ETX_HISTORY_WINDOW;
}
if(le->num_estimates < ETX_HISTORY_WINDOW) {
le->num_estimates++;
}
}
}
/*---------------------------------------------------------------------------*/
void
collect_link_estimate_update_tx_fail(struct collect_link_estimate *le,
uint8_t tx)
{
collect_link_estimate_update_tx(le, tx * 2);
}
/*---------------------------------------------------------------------------*/
void
collect_link_estimate_update_rx(struct collect_link_estimate *n)
{
}
/*---------------------------------------------------------------------------*/
uint16_t
collect_link_estimate(struct collect_link_estimate *le)
{
int i;
uint16_t etx;
if(le->num_estimates == 0) {
return INITIAL_LINK_ESTIMATE * COLLECT_LINK_ESTIMATE_UNIT;
}
PRINTF("collect_link_estimate: ");
etx = 0;
for(i = 0; i < le->num_estimates; ++i) {
PRINTF("%d+", le->history[i]);
etx += le->history[(le->historyptr - i - 1) & (ETX_HISTORY_WINDOW - 1)];
}
PRINTF("/%d = %d\n", i,
(COLLECT_LINK_ESTIMATE_UNIT * etx) / i);
return (COLLECT_LINK_ESTIMATE_UNIT * etx) / i;
}
/*---------------------------------------------------------------------------*/
int
collect_link_estimate_num_estimates(struct collect_link_estimate *le)
{
if(le != NULL) {
return le->num_estimates;
}
return 0;
}
/*---------------------------------------------------------------------------*/
/** @} */