flight/pios/common/pios_deltatime.c

   1 /**
   2  ******************************************************************************
   3  * @addtogroup PIOS PIOS Core hardware abstraction layer
   4  * @{
   5  * @addtogroup PIOS_DELTATIME time measurement Functions
   6  * @brief PiOS Delay functionality
   7  * @{
   8  *
   9  * @file       pios_deltatime.c
  10  * @author     The OpenPilot Team, http://www.openpilot.org Copyright (C) 2010.
  11  * @brief      Settings functions header
  12  * @see        The GNU Public License (GPL) Version 3
  13  *
  14  *****************************************************************************/
  15 /*
  16  * This program is free software; you can redistribute it and/or modify
  17  * it under the terms of the GNU General Public License as published by
  18  * the Free Software Foundation; either version 3 of the License, or
  19  * (at your option) any later version.
  20  *
  21  * This program is distributed in the hope that it will be useful, but
  22  * WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
  23  * or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
  24  * for more details.
  25  *
  26  * You should have received a copy of the GNU General Public License along
  27  * with this program; if not, write to the Free Software Foundation, Inc.,
  28  * 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
  29  */
  30
  31 #include <pios.h>
  32
  33
  34 void PIOS_DELTATIME_Init(PiOSDeltatimeConfig *config, float average, float min, float max, float alpha)
  35 {
  36     PIOS_Assert(config);
  37     config->average = average;
  38     config->min     = min;
  39     config->max     = max;
  40     config->alpha   = alpha;
  41     config->last    = PIOS_DELAY_GetRaw();
  42 };
  43
  44
  45 float PIOS_DELTATIME_GetAverageSeconds(PiOSDeltatimeConfig *config)
  46 {
  47     PIOS_Assert(config);
  48     float dT = PIOS_DELAY_DiffuS(config->last) * 1.0e-6f;
  49     config->last = PIOS_DELAY_GetRaw();
  50     if (dT < config->min) {
  51         dT = config->min;
  52     }
  53     if (dT > config->max) {
  54         dT = config->max;
  55     }
  56     config->average = config->average * (1.0f - config->alpha) + dT * config->alpha;
  57     return config->average;
  58 }
  59
  60
  61 /**
  62  * @}
  63  * @}
  64  */