1 // chrono -*- C++ -*- 2 3 // Copyright (C) 2008-2022 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 #include <chrono> 27 28 // Conditional inclusion of sys/time.h for gettimeofday 29 #if !defined(_GLIBCXX_USE_CLOCK_MONOTONIC) && \ 30 !defined(_GLIBCXX_USE_CLOCK_REALTIME) && \ 31 defined(_GLIBCXX_USE_GETTIMEOFDAY) 32 #include <sys/time.h> 33 #endif 34 35 #ifdef _GLIBCXX_USE_CLOCK_GETTIME_SYSCALL 36 #include <unistd.h> 37 #include <sys/syscall.h> 38 #endif 39 40 namespace std _GLIBCXX_VISIBILITY(default) 41 { 42 _GLIBCXX_BEGIN_NAMESPACE_VERSION 43 44 namespace chrono 45 { 46 _GLIBCXX_BEGIN_INLINE_ABI_NAMESPACE(_V2) 47 48 constexpr bool system_clock::is_steady; 49 50 system_clock::time_point now()51 system_clock::now() noexcept 52 { 53 #ifdef _GLIBCXX_USE_CLOCK_REALTIME 54 timespec tp; 55 // -EINVAL, -EFAULT 56 #ifdef _GLIBCXX_USE_CLOCK_GETTIME_SYSCALL 57 syscall(SYS_clock_gettime, CLOCK_REALTIME, &tp); 58 #else 59 clock_gettime(CLOCK_REALTIME, &tp); 60 #endif 61 return time_point(duration(chrono::seconds(tp.tv_sec) 62 + chrono::nanoseconds(tp.tv_nsec))); 63 #elif defined(_GLIBCXX_USE_GETTIMEOFDAY) 64 timeval tv; 65 // EINVAL, EFAULT 66 gettimeofday(&tv, 0); 67 return time_point(duration(chrono::seconds(tv.tv_sec) 68 + chrono::microseconds(tv.tv_usec))); 69 #else 70 std::time_t __sec = std::time(0); 71 return system_clock::from_time_t(__sec); 72 #endif 73 } 74 75 76 constexpr bool steady_clock::is_steady; 77 78 steady_clock::time_point now()79 steady_clock::now() noexcept 80 { 81 #ifdef _GLIBCXX_USE_CLOCK_MONOTONIC 82 timespec tp; 83 // -EINVAL, -EFAULT 84 #ifdef _GLIBCXX_USE_CLOCK_GETTIME_SYSCALL 85 syscall(SYS_clock_gettime, CLOCK_MONOTONIC, &tp); 86 #else 87 clock_gettime(CLOCK_MONOTONIC, &tp); 88 #endif 89 return time_point(duration(chrono::seconds(tp.tv_sec) 90 + chrono::nanoseconds(tp.tv_nsec))); 91 #else 92 return time_point(system_clock::now().time_since_epoch()); 93 #endif 94 } 95 96 _GLIBCXX_END_INLINE_ABI_NAMESPACE(_V2) 97 } // namespace chrono 98 99 _GLIBCXX_END_NAMESPACE_VERSION 100 } // namespace std 101