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

   1 // Compatibility symbols for previous versions, C++0x bits -*- C++ -*-
   2
   3 // Copyright (C) 2013-2016 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 <bits/c++config.h>
  26
  27 #ifdef _GLIBCXX_USE_C99_STDINT_TR1
  28
  29 #ifdef _GLIBCXX_USE_GETTIMEOFDAY
  30 #include <sys/time.h>
  31 #endif
  32
  33 #define system_clock system_clockXX
  34 #define steady_clock steady_clockXX
  35 #include <chrono>
  36 #undef system_clock
  37 #undef steady_clock
  38
  39 namespace std _GLIBCXX_VISIBILITY(default)
  40 {
  41   namespace chrono
  42   {
  43   _GLIBCXX_BEGIN_NAMESPACE_VERSION
  44
  45     // NB: Default configuration was no realtime.
  46     struct system_clock
  47     {
  48 #ifdef _GLIBCXX_USE_GETTIMEOFDAY
  49       typedef chrono::microseconds                              duration;
  50 #else
  51       typedef chrono::seconds                                   duration;
  52 #endif
  53
  54       typedef duration::rep                                     rep;
  55       typedef duration::period                                  period;
  56       typedef chrono::time_point<system_clock, duration>        time_point;
  57
  58       static_assert(system_clock::duration::min()
  59                     < system_clock::duration::zero(),
  60                     "a clock's minimum duration cannot be less than its epoch");
  61
  62       static constexpr bool is_steady = false;
  63
  64       static time_point
  65       now() noexcept;
  66     };
  67
  68     constexpr bool system_clock::is_steady;
  69
  70     system_clock::time_point
  71     system_clock::now() noexcept
  72     {
  73 #ifdef _GLIBCXX_USE_GETTIMEOFDAY
  74       timeval tv;
  75       // EINVAL, EFAULT
  76       gettimeofday(&tv, 0);
  77       return time_point(duration(chrono::seconds(tv.tv_sec)
  78                                  + chrono::microseconds(tv.tv_usec)));
  79 #else
  80       std::time_t __sec = std::time(0);
  81       // This is the conversion done by system_clock::from_time_t(__sec)
  82       typedef chrono::time_point<system_clock, seconds> __from;
  83       return time_point_cast<system_clock::duration>
  84              (__from(chrono::seconds(__sec)));
  85 #endif
  86     }
  87
  88   _GLIBCXX_END_NAMESPACE_VERSION
  89   } // namespace chrono
  90 } // namespace std
  91
  92 #endif // _GLIBCXX_USE_C99_STDINT_TR1