timer.h

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* Copyright (c) 2016, Robert van Engelen, Genivia Inc. All rights reserved.    *
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/**
@file      timer.h
@brief     Measure elapsed wall-clock time in milliseconds
@author    Robert van Engelen - engelen@genivia.com
@copyright (c) 2016-2020, Robert van Engelen, Genivia Inc. All rights reserved.
@copyright (c) BSD-3 License - see LICENSE.txt
*/

#ifndef REFLEX_TIMER_H
#define REFLEX_TIMER_H

#if defined(__WIN32__) || defined(_WIN32) || defined(WIN32) || defined(_WIN64) || defined(__CYGWIN__) || defined(__MINGW32__) || defined(__MINGW64__) || defined(__BORLANDC__)

#include <windows.h>

namespace reflex {

typedef SYSTEMTIME timer_type;

/// Start timer.
inline void timer_start(timer_type& t) ///< timer to be initialized
{
  GetLocalTime(&t);
}

/// Return elapsed time in milliseconds (ms) since the last call up to 1 minute (wraps if elapsed time exceeds 1 minute!)
inline float timer_elapsed(timer_type& t) ///< timer to be updated
{
  timer_type now;
  GetLocalTime(&now);
  float sec = now.wMilliseconds;
  sec -= t.wMilliseconds;
  t.wMilliseconds = now.wMilliseconds;
  sec += 1000.0f * (now.wSecond - t.wSecond);
  t.wSecond = now.wSecond;
  if (sec < 0.0)
    sec += 60000.0;
  return sec;
}

} // namespace reflex

#else

#include <cstddef>
#include <sys/time.h>

namespace reflex {

typedef timeval timer_type;

/// Start timer.
inline void timer_start(timer_type& t) ///< timer to be initialized
{
  gettimeofday(&t, NULL);
}

/// Return elapsed time in milliseconds (ms) with microsecond precision since the last call up to 1 minute (wraps if elapsed time exceeds 1 minute!)
inline float timer_elapsed(timer_type& t) ///< timer to be updated
{
  timer_type now;
  gettimeofday(&now, NULL);
  float sec = now.tv_usec;
  sec -= t.tv_usec;
  t.tv_usec = now.tv_usec;
  sec = 1000.0 * (now.tv_sec - t.tv_sec) + sec/1000.0;
  t.tv_sec = now.tv_sec;
  if (sec < 0.0)
    sec += 60000.0;
  return sec;
}

} // namespace reflex

#endif

#endif