37 lines
1001 B
C++
37 lines
1001 B
C++
// SPDX-License-Identifier: BSD-2-Clause
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// author: Max Kellermann <max.kellermann@gmail.com>
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#pragma once
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#include <chrono>
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/**
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* Calculate a std::chrono::system_clock::time_point from a duration
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* relative to the UNIX epoch (1970-01-01T00:00Z).
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*/
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template<class Rep, class Period>
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[[gnu::const]]
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std::chrono::system_clock::time_point
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TimePointAfterUnixEpoch(const std::chrono::duration<Rep,Period> d) noexcept
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{
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/* this is guaranteed to be 0 in C++20 */
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const auto unix_epoch = std::chrono::system_clock::from_time_t(0);
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return unix_epoch +
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std::chrono::duration_cast<std::chrono::system_clock::duration>(d);
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}
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/**
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* Calculate the duration that has passed since the UNIX epoch
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* (1970-01-01T00:00Z).
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*/
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[[gnu::const]]
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inline std::chrono::system_clock::duration
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DurationSinceUnixEpoch(const std::chrono::system_clock::time_point tp) noexcept
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{
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/* this is guaranteed to be 0 in C++20 */
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const auto unix_epoch = std::chrono::system_clock::from_time_t(0);
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return tp - unix_epoch;
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}
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