chtm.c

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/*
    ChibiOS - Copyright (C) 2006,2007,2008,2009,2010,2011,2012,2013,2014,
              2015,2016,2017,2018,2019,2020,2021 Giovanni Di Sirio.
 
    This file is part of ChibiOS.
 
    ChibiOS is free software; you can redistribute it and/or modify
    it under the terms of the GNU General Public License as published by
    the Free Software Foundation version 3 of the License.
 
    ChibiOS is distributed in the hope that it will be useful,
    but WITHOUT ANY WARRANTY; without even the implied warranty of
    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
    GNU General Public License for more details.
 
    You should have received a copy of the GNU General Public License
    along with this program.  If not, see <http://www.gnu.org/licenses/>.
*/
 
/**
 * @file    rt/src/chtm.c
 * @brief   Time Measurement module code.
 *
 * @addtogroup time_measurement
 * @details Time Measurement APIs and services.
 * @{
 */
 
#include "ch.h"
 
#if (CH_CFG_USE_TM == TRUE) || defined(__DOXYGEN__)
 
/*===========================================================================*/
/* Module local definitions.                                                 */
/*===========================================================================*/
 
/**
 * @brief   Number of iterations in the calibration loop.
 * @note    This is required in order to assess the best result in
 *          architectures with instruction cache.
 */
#define TM_CALIBRATION_LOOP             4U
 
/*===========================================================================*/
/* Module exported variables.                                                */
/*===========================================================================*/
 
/*===========================================================================*/
/* Module local types.                                                       */
/*===========================================================================*/
 
/*===========================================================================*/
/* Module local variables.                                                   */
/*===========================================================================*/
 
/*===========================================================================*/
/* Module local functions.                                                   */
/*===========================================================================*/
 
static inline void tm_stop(time_measurement_t *tmp,
                           rtcnt_t now,
                           rtcnt_t offset) {
 
  tmp->n++;
  tmp->last = (now - tmp->last) - offset;
  tmp->cumulative += (rttime_t)tmp->last;
  if (tmp->last > tmp->worst) {
    tmp->worst = tmp->last;
  }
  if (tmp->last < tmp->best) {
    tmp->best = tmp->last;
  }
}
 
/*===========================================================================*/
/* Module exported functions.                                                */
/*===========================================================================*/
 
/**
 * @brief   Initializes the time measurement unit.
 *
 * @init
 */
void _tm_init(void) {
  time_measurement_t tm;
  unsigned i;
 
  /* Time Measurement subsystem calibration, it does a null measurement
     and calculates the call overhead which is subtracted to real
     measurements.*/
  ch.tm.offset = (rtcnt_t)0;
  chTMObjectInit(&tm);
  i = TM_CALIBRATION_LOOP;
  do {
    chTMStartMeasurementX(&tm);
    chTMStopMeasurementX(&tm);
    i--;
  } while (i > 0U);
  ch.tm.offset = tm.best;
}
 
/**
 * @brief   Initializes a @p TimeMeasurement object.
 *
 * @param[out] tmp      pointer to a @p TimeMeasurement structure
 *
 * @init
 */
void chTMObjectInit(time_measurement_t *tmp) {
 
  tmp->best       = (rtcnt_t)-1;
  tmp->worst      = (rtcnt_t)0;
  tmp->last       = (rtcnt_t)0;
  tmp->n          = (ucnt_t)0;
  tmp->cumulative = (rttime_t)0;
}
 
/**
 * @brief   Starts a measurement.
 * @pre     The @p time_measurement_t structure must be initialized.
 *
 * @param[in,out] tmp   pointer to a @p TimeMeasurement structure
 *
 * @xclass
 */
NOINLINE void chTMStartMeasurementX(time_measurement_t *tmp) {
 
  tmp->last = chSysGetRealtimeCounterX();
}
 
/**
 * @brief   Stops a measurement.
 * @pre     The @p time_measurement_t structure must be initialized.
 *
 * @param[in,out] tmp   pointer to a @p time_measurement_t structure
 *
 * @xclass
 */
NOINLINE void chTMStopMeasurementX(time_measurement_t *tmp) {
 
  tm_stop(tmp, chSysGetRealtimeCounterX(), ch.tm.offset);
}
 
/**
 * @brief   Stops a measurement and chains to the next one using the same time
 *          stamp.
 *
 * @param[in,out] tmp1  pointer to the @p time_measurement_t structure to be
 *                      stopped
 * @param[in,out] tmp2  pointer to the @p time_measurement_t structure to be
 *                      started
 *
 *
 * @xclass
 */
NOINLINE void chTMChainMeasurementToX(time_measurement_t *tmp1,
                                      time_measurement_t *tmp2) {
 
  /* Starts new measurement.*/
  tmp2->last = chSysGetRealtimeCounterX();
 
  /* Stops previous measurement using the same time stamp.*/
  tm_stop(tmp1, tmp2->last, (rtcnt_t)0);
}
 
#endif /* CH_CFG_USE_TM == TRUE */
 
/** @} */