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