src/libswift/avgspeed.cpp

   1 /*
   2  *  avgspeed.cpp
   3  *  Class to compute moving average speed
   4  *
   5  *  Created by Arno Bakker
   6  *  Copyright 2009 Delft University of Technology. All rights reserved.
   7  *
   8  */
   9 #include "avgspeed.h"
  10
  11 using namespace swift;
  12
  13 MovingAverageSpeed::MovingAverageSpeed(tint speed_interval, tint fudge)
  14 {
  15     speed_interval_ = speed_interval;
  16     fudge_ = fudge;
  17         t_start_ = usec_time() - fudge_;
  18         t_end_ = t_start_;
  19         speed_ = 0.0;
  20         resetstate_ = false;
  21 }
  22
  23
  24 void MovingAverageSpeed::AddPoint(uint64_t amount)
  25 {
  26         // Arno, 2012-01-04: Resetting this measurement includes not adding
  27         // points for a few seconds after the reset, to accomodate the case
  28         // of going from high speed to low speed and content still coming in.
  29         //
  30         if (resetstate_) {
  31                 if ((t_start_ + speed_interval_/2) > usec_time()) {
  32                         return;
  33                 }
  34                 resetstate_ = false;
  35         }
  36
  37     tint t = usec_time();
  38     speed_ = (speed_ * ((double)(t_end_ - t_start_)/((double)TINT_SEC)) + (double)amount) / ((t - t_start_)/((double)TINT_SEC) + 0.0001);
  39     t_end_ = t;
  40     if (t_start_ < t - speed_interval_)
  41         t_start_ = t - speed_interval_;
  42 }
  43
  44
  45 double MovingAverageSpeed::GetSpeed()
  46 {
  47     AddPoint(0);
  48     return speed_;
  49 }
  50
  51
  52 double MovingAverageSpeed::GetSpeedNeutral()
  53 {
  54     return speed_;
  55 }
  56
  57
  58 void MovingAverageSpeed::Reset()
  59 {
  60         resetstate_ = true;
  61         t_start_ = usec_time() - fudge_;
  62         t_end_ = t_start_;
  63         speed_ = 0.0;
  64 }