time.h

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// Copyright 2015-2016, Open Source Robotics Foundation, Inc. All rights reserved.
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#ifndef TF2__TIME_H_
#define TF2__TIME_H_
 
#include <chrono>
#include <cmath>
#include <string>
 
#include "tf2/visibility_control.h"
 
namespace tf2
{
using Duration = std::chrono::nanoseconds;
using TimePoint = std::chrono::time_point<std::chrono::system_clock, Duration>;
 
using IDuration = std::chrono::duration<int, std::nano>;
// This is the zero time in ROS
static const TimePoint TimePointZero = TimePoint(IDuration::zero());
 
inline TimePoint get_now()
{
  return std::chrono::system_clock::now();
}
 
inline Duration durationFromSec(double t_sec)
{
  int32_t sec, nsec;
  sec = static_cast<int32_t>(floor(t_sec));
  nsec = static_cast<int32_t>(std::round((t_sec - sec) * 1e9));
  // avoid rounding errors
  sec += (nsec / 1000000000l);
  nsec %= 1000000000l;
  return std::chrono::seconds(sec) + std::chrono::nanoseconds(nsec);
}
 
inline TimePoint timeFromSec(double t_sec)
{
  return tf2::TimePoint(durationFromSec(t_sec));
}
 
inline double durationToSec(const tf2::Duration & input)
{
  int64_t count = input.count();
 
  // scale the nanoseconds separately for improved accuracy
  int32_t sec, nsec;
  nsec = static_cast<int32_t>(count % 1000000000l);
  sec = static_cast<int32_t>((count - nsec) / 1000000000l);
 
  double sec_double, nsec_double;
  nsec_double = 1e-9 * static_cast<double>(nsec);
  sec_double = static_cast<double>(sec);
  return sec_double + nsec_double;
}
 
inline double timeToSec(const TimePoint & timepoint)
{
  return durationToSec(Duration(timepoint.time_since_epoch()));
}
 
TF2_PUBLIC
std::string displayTimePoint(const TimePoint & stamp);
 
}  // namespace tf2
 
#endif  // TF2__TIME_H_