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
  10 #ifndef _LIBCPP___CHRONO_CONVERT_TO_TIMESPEC_H
  11 #define _LIBCPP___CHRONO_CONVERT_TO_TIMESPEC_H
  12
  13 #include <__chrono/duration.h>
  14 #include <__config>
  15 #include <limits>
  16
  17 #if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
  18 #  pragma GCC system_header
  19 #endif
  20
  21 _LIBCPP_PUSH_MACROS
  22 #include <__undef_macros>
  23
  24 _LIBCPP_BEGIN_NAMESPACE_STD
  25
  26 // Convert a nanoseconds duration to the given TimeSpec type, which must have
  27 // the same properties as std::timespec.
  28 template <class _TimeSpec>
  29 _LIBCPP_HIDE_FROM_ABI inline _TimeSpec __convert_to_timespec(const chrono::nanoseconds& __ns) {
  30   using namespace chrono;
  31   seconds __s = duration_cast<seconds>(__ns);
  32   _TimeSpec __ts;
  33   typedef decltype(__ts.tv_sec) __ts_sec;
  34   const __ts_sec __ts_sec_max = numeric_limits<__ts_sec>::max();
  35
  36   if (__s.count() < __ts_sec_max) {
  37     __ts.tv_sec  = static_cast<__ts_sec>(__s.count());
  38     __ts.tv_nsec = static_cast<decltype(__ts.tv_nsec)>((__ns - __s).count());
  39   } else {
  40     __ts.tv_sec  = __ts_sec_max;
  41     __ts.tv_nsec = 999999999; // (10^9 - 1)
  42   }
  43
  44   return __ts;
  45 }
  46
  47 _LIBCPP_END_NAMESPACE_STD
  48
  49 _LIBCPP_POP_MACROS
  50
  51 #endif // _LIBCPP___CHRONO_CONVERT_TO_TIMESPEC_H