libcxx/include/__chrono/convert_to_timespec.h

   1 // -*- C++ -*-
   2 //===----------------------------------------------------------------------===//
   3 //
   4 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
   5 // See https://llvm.org/LICENSE.txt for license information.
   6 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
   7 //
   8 //===----------------------------------------------------------------------===//
   9 #ifndef _LIBCPP___CHRONO_CONVERT_TO_TIMESPEC_H
  10 #define _LIBCPP___CHRONO_CONVERT_TO_TIMESPEC_H
  11
  12 #include <__chrono/duration.h>
  13 #include <__config>
  14 #include <limits>
  15
  16 #if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
  17 #pragma GCC system_header
  18 #endif
  19
  20 _LIBCPP_PUSH_MACROS
  21 #include <__undef_macros>
  22
  23 _LIBCPP_BEGIN_NAMESPACE_STD
  24
  25 // Convert a nanoseconds duration to the given TimeSpec type, which must have
  26 // the same properties as std::timespec.
  27 template <class _TimeSpec>
  28 _LIBCPP_HIDE_FROM_ABI inline
  29 _TimeSpec __convert_to_timespec(const chrono::nanoseconds& __ns)
  30 {
  31   using namespace chrono;
  32   seconds __s = duration_cast<seconds>(__ns);
  33   _TimeSpec __ts;
  34   typedef decltype(__ts.tv_sec) __ts_sec;
  35   const __ts_sec __ts_sec_max = numeric_limits<__ts_sec>::max();
  36
  37   if (__s.count() < __ts_sec_max)
  38   {
  39     __ts.tv_sec = static_cast<__ts_sec>(__s.count());
  40     __ts.tv_nsec = static_cast<decltype(__ts.tv_nsec)>((__ns - __s).count());
  41   }
  42   else
  43   {
  44     __ts.tv_sec = __ts_sec_max;
  45     __ts.tv_nsec = 999999999; // (10^9 - 1)
  46   }
  47
  48   return __ts;
  49 }
  50
  51 _LIBCPP_END_NAMESPACE_STD
  52
  53 _LIBCPP_POP_MACROS
  54
  55 #endif // _LIBCPP___CHRONO_CONVERT_TO_TIMESPEC_H