text: /******************************************************************************\
  * Copyright (c) 2016, Robert van Engelen, Genivia Inc. All rights reserved.    *
  *                                                                              *
  * Redistribution and use in source and binary forms, with or without           *
  * modification, are permitted provided that the following conditions are met:  *
  *                                                                              *
  *   (1) Redistributions of source code must retain the above copyright notice, *
  *       this list of conditions and the following disclaimer.                  *
  *                                                                              *
  *   (2) Redistributions in binary form must reproduce the above copyright      *
  *       notice, this list of conditions and the following disclaimer in the    *
  *       documentation and/or other materials provided with the distribution.   *
  *                                                                              *
  *   (3) The name of the author may not be used to endorse or promote products  *
  *       derived from this software without specific prior written permission.  *
  *                                                                              *
  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR IMPLIED *
  * WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF         *
  * MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO   *
  * EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,       *
  * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, *
  * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS;  *
  * OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY,     *
  * WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR      *
  * OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF       *
  * ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.                                   *
  \******************************************************************************/
  
  /**
  @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, nullptr);
  }
  
  /// 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, nullptr);
    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
  