text: #ifndef BOOST_THREAD_PTHREAD_TIMESPEC_HPP
  #define BOOST_THREAD_PTHREAD_TIMESPEC_HPP
  //  (C) Copyright 2007-8 Anthony Williams
  //  (C) Copyright 2012 Vicente J. Botet Escriba
  //
  //  Distributed under the Boost Software License, Version 1.0. (See
  //  accompanying file LICENSE_1_0.txt or copy at
  //  http://www.boost.org/LICENSE_1_0.txt)
  
  #include <boost/thread/detail/config.hpp>
  #include <boost/thread/thread_time.hpp>
  #if defined BOOST_THREAD_USES_DATETIME
  #include <boost/date_time/posix_time/conversion.hpp>
  #endif
  #include <pthread.h>
  #ifndef _WIN32
  #include <unistd.h>
  #endif
  #ifdef BOOST_THREAD_USES_CHRONO
  #include <boost/chrono/duration.hpp>
  #endif
  
  #if defined(macintosh) || defined(__APPLE__) || defined(__APPLE_CC__)
  #     define BOOST_THREAD_TIMESPEC_MAC_API
  #include <sys/time.h> //for gettimeofday and timeval
  #else
  #include <time.h>  // for clock_gettime
  #endif
  
  #include <boost/config/abi_prefix.hpp>
  
  namespace boost
  {
    namespace detail
    {
  #if defined BOOST_THREAD_USES_DATETIME
      inline struct timespec to_timespec(boost::system_time const& abs_time)
      {
        struct timespec timeout = { 0,0};
        boost::posix_time::time_duration const time_since_epoch=abs_time-boost::posix_time::from_time_t(0);
  
        timeout.tv_sec=time_since_epoch.total_seconds();
        timeout.tv_nsec=(long)(time_since_epoch.fractional_seconds()*(1000000000l/time_since_epoch.ticks_per_second()));
        return timeout;
      }
  #endif
  #if defined BOOST_THREAD_USES_CHRONO
      inline timespec to_timespec(chrono::nanoseconds const& ns)
      {
        struct timespec ts;
        ts.tv_sec = static_cast<long>(chrono::duration_cast<chrono::seconds>(ns).count());
        ts.tv_nsec = static_cast<long>((ns - chrono::duration_cast<chrono::seconds>(ns)).count());
        return ts;
      }
  
  #endif
  
      inline timespec to_timespec(boost::intmax_t const& ns)
      {
        boost::intmax_t s = ns / 1000000000l;
        struct timespec ts;
        ts.tv_sec = static_cast<long> (s);
        ts.tv_nsec = static_cast<long> (ns - s * 1000000000l);
        return ts;
      }
      inline boost::intmax_t to_nanoseconds_int_max(timespec const& ts)
      {
        return static_cast<boost::intmax_t>(ts.tv_sec) * 1000000000l + ts.tv_nsec;
      }
      inline bool timespec_ge_zero(timespec const& ts)
      {
        return (ts.tv_sec >= 0) || (ts.tv_nsec >= 0);
      }
      inline timespec timespec_now()
      {
        timespec ts;
  
  #if defined(BOOST_THREAD_TIMESPEC_MAC_API)
        timeval tv;
        ::gettimeofday(&tv, 0);
        ts.tv_sec = tv.tv_sec;
        ts.tv_nsec = tv.tv_usec * 1000;
  #else
        if ( ::clock_gettime( CLOCK_REALTIME, &ts ) )
        {
          BOOST_ASSERT(0 && "Boost::Thread - Internal Error");
        }
  #endif
        return ts;
      }
      inline timespec timespec_zero()
      {
        timespec ts;
        ts.tv_sec = 0;
        ts.tv_nsec = 0;
        return ts;
      }
      inline timespec timespec_plus(timespec const& lhs, timespec const& rhs)
      {
        return to_timespec(to_nanoseconds_int_max(lhs) + to_nanoseconds_int_max(rhs));
      }
      inline timespec timespec_minus(timespec const& lhs, timespec const& rhs)
      {
        return to_timespec(to_nanoseconds_int_max(lhs) - to_nanoseconds_int_max(rhs));
      }
      inline bool timespec_gt(timespec const& lhs, timespec const& rhs)
      {
        return to_nanoseconds_int_max(lhs) > to_nanoseconds_int_max(rhs);
      }
      inline bool timespec_ge(timespec const& lhs, timespec const& rhs)
      {
        return to_nanoseconds_int_max(lhs) >= to_nanoseconds_int_max(rhs);
      }
  
    }
  }
  
  #include <boost/config/abi_suffix.hpp>
  
  #endif
  