libstdc++-v3/src/c++11/chrono.cc

   1 // chrono -*- C++ -*-
   2
   3 // Copyright (C) 2008-2013 Free Software Foundation, Inc.
   4 //
   5 // This file is part of the GNU ISO C++ Library.  This library is free
   6 // software; you can redistribute it and/or modify it under the
   7 // terms of the GNU General Public License as published by the
   8 // Free Software Foundation; either version 3, or (at your option)
   9 // any later version.
  10
  11 // This library is distributed in the hope that it will be useful,
  12 // but WITHOUT ANY WARRANTY; without even the implied warranty of
  13 // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  14 // GNU General Public License for more details.
  15
  16 // Under Section 7 of GPL version 3, you are granted additional
  17 // permissions described in the GCC Runtime Library Exception, version
  18 // 3.1, as published by the Free Software Foundation.
  19
  20 // You should have received a copy of the GNU General Public License and
  21 // a copy of the GCC Runtime Library Exception along with this program;
  22 // see the files COPYING3 and COPYING.RUNTIME respectively.  If not, see
  23 // <http://www.gnu.org/licenses/>.
  24
  25 #include <chrono>
  26
  27 #ifdef _GLIBCXX_USE_C99_STDINT_TR1
  28
  29 // conditional inclusion of sys/time.h for gettimeofday
  30 #if !defined(_GLIBCXX_USE_CLOCK_MONOTONIC) && \
  31     !defined(_GLIBCXX_USE_CLOCK_REALTIME) && \
  32      defined(_GLIBCXX_USE_GETTIMEOFDAY)
  33 #include <sys/time.h>
  34 #endif
  35
  36 namespace std _GLIBCXX_VISIBILITY(default)
  37 {
  38   namespace chrono
  39   {
  40   _GLIBCXX_BEGIN_NAMESPACE_VERSION
  41
  42     constexpr bool system_clock::is_steady;
  43
  44     system_clock::time_point
  45     system_clock::now() noexcept
  46     {
  47 #ifdef _GLIBCXX_USE_CLOCK_REALTIME
  48       timespec tp;
  49       // -EINVAL, -EFAULT
  50       clock_gettime(CLOCK_REALTIME, &tp);
  51       return time_point(duration(chrono::seconds(tp.tv_sec)
  52                                  + chrono::nanoseconds(tp.tv_nsec)));
  53 #elif defined(_GLIBCXX_USE_GETTIMEOFDAY)
  54       timeval tv;
  55       // EINVAL, EFAULT
  56       gettimeofday(&tv, 0);
  57       return time_point(duration(chrono::seconds(tv.tv_sec)
  58                                  + chrono::microseconds(tv.tv_usec)));
  59 #else
  60       std::time_t __sec = std::time(0);
  61       return system_clock::from_time_t(__sec);
  62 #endif
  63     }
  64
  65 #ifdef _GLIBCXX_USE_CLOCK_MONOTONIC
  66     constexpr bool steady_clock::is_steady;
  67
  68     steady_clock::time_point
  69     steady_clock::now() noexcept
  70     {
  71       timespec tp;
  72       // -EINVAL, -EFAULT
  73       clock_gettime(CLOCK_MONOTONIC, &tp);
  74       return time_point(duration(chrono::seconds(tp.tv_sec)
  75                                  + chrono::nanoseconds(tp.tv_nsec)));
  76     }
  77 #endif
  78
  79   _GLIBCXX_END_NAMESPACE_VERSION
  80   } // namespace chrono
  81 } // namespace std
  82
  83 #endif // _GLIBCXX_USE_C99_STDINT_TR1