text: /*
   * Author: Jon Trulson <jtrulson@ics.com>
   * Copyright (c) 2014 Intel Corporation.
   *
   * Permission is hereby granted, free of charge, to any person obtaining
   * a copy of this software and associated documentation files (the
   * "Software"), to deal in the Software without restriction, including
   * without limitation the rights to use, copy, modify, merge, publish,
   * distribute, sublicense, and/or sell copies of the Software, and to
   * permit persons to whom the Software is furnished to do so, subject to
   * the following conditions:
   *
   * The above copyright notice and this permission notice shall be
   * included in all copies or substantial portions of the Software.
   *
   * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
   * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
   * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
   * NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE
   * LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
   * OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
   * WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
   */
  
  #include <iostream>
  #include <string>
  #include <stdexcept>
  
  #include "groveehr.h"
  
  using namespace upm;
  using namespace std;
  
  GroveEHR::GroveEHR(int pin)
  {
    if ( !(m_gpio = mraa_gpio_init(pin)) )
      {
        throw std::invalid_argument(std::string(__FUNCTION__) +
                                    ": mraa_aio_init() failed, invalid pin?");
        return;
      }
  
    mraa_gpio_dir(m_gpio, MRAA_GPIO_IN);
  
    initClock();
    m_beatCounter = 0;
  }
  
  GroveEHR::~GroveEHR()
  {
    mraa_gpio_close(m_gpio);
  }
  
  void GroveEHR::initClock()
  {
    gettimeofday(&m_startTime, NULL);
  }
  
  uint32_t GroveEHR::getMillis()
  {
    struct timeval elapsed, now;
    uint32_t elapse;
  
    // get current time
    gettimeofday(&now, NULL);
  
    // compute the delta since m_startTime
    if( (elapsed.tv_usec = now.tv_usec - m_startTime.tv_usec) < 0 ) 
      {
        elapsed.tv_usec += 1000000;
        elapsed.tv_sec = now.tv_sec - m_startTime.tv_sec - 1;
      } 
    else 
      {
        elapsed.tv_sec = now.tv_sec - m_startTime.tv_sec;
      }
  
    elapse = (uint32_t)((elapsed.tv_sec * 1000) + (elapsed.tv_usec / 1000));
  
    // never return 0
    if (elapse == 0)
      elapse = 1;
  
    return elapse;
  }
  
  void GroveEHR::clearBeatCounter()
  {
    m_beatCounter = 0;
  }
  
  void GroveEHR::startBeatCounter()
  {
    // install our interrupt handler
    mraa_gpio_isr(m_gpio, MRAA_GPIO_EDGE_RISING, 
                  &beatISR, this);
  }
  
  void GroveEHR::stopBeatCounter()
  {
    // remove the interrupt handler
    mraa_gpio_isr_exit(m_gpio);
  }
  
  uint32_t GroveEHR::beatCounter()
  {
    return m_beatCounter;
  }
  
  void GroveEHR::beatISR(void *ctx)
  {
    upm::GroveEHR *This = (upm::GroveEHR *)ctx;
    This->m_beatCounter++;
  }
  
  int GroveEHR::heartRate()
  {
    uint32_t millis = getMillis();
    uint32_t beats = beatCounter();
    
    float heartRate = 0;
    // wait at least 5 seconds before attempting to compute the
    // heart rate
    if (millis > 5000)
      {
        heartRate = (float(beats) / (float(millis) / 1000.0)) * 60.0;
      }
  
    return int(heartRate);
  }
  