src/Computer/ClimbAverageCalculator.cpp

   1 /*
   2 Copyright_License {
   3
   4   XCSoar Glide Computer - http://www.xcsoar.org/
   5   Copyright (C) 2000-2013 The XCSoar Project
   6   A detailed list of copyright holders can be found in the file "AUTHORS".
   7
   8   This program is free software; you can redistribute it and/or
   9   modify it under the terms of the GNU General Public License
  10   as published by the Free Software Foundation; either version 2
  11   of the License, or (at your option) any later version.
  12
  13   This program is distributed in the hope that it will be useful,
  14   but WITHOUT ANY WARRANTY; without even the implied warranty of
  15   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  16   GNU General Public License for more details.
  17
  18   You should have received a copy of the GNU General Public License
  19   along with this program; if not, write to the Free Software
  20   Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA  02111-1307, USA.
  21 }
  22 */
  23
  24 #include "ClimbAverageCalculator.hpp"
  25
  26 void
  27 ClimbAverageCalculator::Reset()
  28 {
  29   newestValIndex = -1;
  30   for (int i = 0; i < MAX_HISTORY; i++)
  31     history[i].Reset();
  32 }
  33
  34 fixed
  35 ClimbAverageCalculator::GetAverage(fixed time, fixed altitude, fixed average_time)
  36 {
  37   assert(average_time <= fixed(MAX_HISTORY));
  38
  39   int bestHistory;
  40
  41   // Don't update newestValIndex if the time didn't move forward
  42   if (newestValIndex < 0 ||
  43       !history[newestValIndex].IsDefined() ||
  44       time > history[newestValIndex].time)
  45     newestValIndex = newestValIndex < MAX_HISTORY - 1 ? newestValIndex + 1 : 0;
  46
  47   // add the new sample
  48   history[newestValIndex] = HistoryItem(time, altitude);
  49
  50   // initially bestHistory is the current...
  51   bestHistory = newestValIndex;
  52
  53   // now run through the history and find the best sample
  54   // for average period within the average time period
  55   for (int i = 0; i < MAX_HISTORY; i++) {
  56     if (!history[i].IsDefined())
  57       continue;
  58
  59     // outside the period -> skip value
  60     if (history[i].time + average_time < time)
  61       continue;
  62
  63     // is the sample older (and therefore better) than the current found ?
  64     if (history[i].time < history[bestHistory].time)
  65       bestHistory = i;
  66   }
  67
  68   // calculate the average !
  69   if (bestHistory != newestValIndex)
  70     return (altitude - history[bestHistory].altitude) /
  71            (time - history[bestHistory].time);
  72
  73   return fixed(0);
  74 }
  75
  76 bool
  77 ClimbAverageCalculator::Expired(fixed now, fixed max_age) const
  78 {
  79   if (newestValIndex < 0)
  80     return true;
  81
  82   auto item = history[newestValIndex];
  83   if (!item.IsDefined())
  84     return true;
  85
  86   return now < item.time || now > item.time + max_age;
  87 }