mirror of https://github.com/ARMmbed/mbed-os.git
129 lines
3.7 KiB
C++
129 lines
3.7 KiB
C++
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/*
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* Copyright (c) 2015-2019, ARM Limited, All Rights Reserved
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* SPDX-License-Identifier: Apache-2.0
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*
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* Licensed under the Apache License, Version 2.0 (the "License"); you may
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* not use this file except in compliance with the License.
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* You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
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* WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*/
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#ifndef __MBED_CHRONO_H__
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#define __MBED_CHRONO_H__
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#include "mbed_toolchain.h"
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#include <cstdint>
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#include <cassert>
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#include <ratio>
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#include <chrono>
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/** \addtogroup platform-public-api */
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/** @{*/
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/**
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* \defgroup platform_chrono chrono utilities
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*
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* Additions and variations of std::chrono
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*
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* - unsigned 32-bit variants of standard signed 64-bit duration types
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* - centiseconds and deciseconds
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* @{
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*/
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namespace mbed {
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/* Extensions declared in mbed::chrono, following pattern of std::chrono */
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namespace chrono {
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/* Add deciseconds and centiseconds - may be
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* useful to use lower precision when not messing with templating.
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*/
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using deciseconds = std::chrono::duration<long long, std::deci>;
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using centiseconds = std::chrono::duration<long long, std::centi>;
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/** 32-bit microsecond duration type
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*
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* Standard std::chrono::microseconds is signed 64-bit. For some purposes
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* it's more efficient to process small times as 32-bit. And when doing so,
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* as we likely need to worry about wrapping, use of an unsigned
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* value to process modulo 2**32 is appropriate.
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*/
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using microseconds_u32 = std::chrono::duration<std::uint32_t, std::micro>;
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/** 32-bit millisecond duration type
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*
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* Standard std::chrono::milliseconds is signed 64-bit. For some purposes
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* it's more efficient to process times as 32-bit. And when doing so,
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* as we likely need to worry about wrapping, use of an unsigned
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* value to process modulo 2**32 is appropriate.
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*/
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using milliseconds_u32 = std::chrono::duration<std::uint32_t, std::milli>;
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} // namespace chrono
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inline namespace literals {
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inline namespace chrono_literals {
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/** User-defined literal for deciseconds (1/10 of a second)
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*
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* Useful in case we might change kernel tick frequency to be slower - with tick frequency 1000Hz, it is
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* possible to assign 500ms to a KernelClock::duration, but that would fail at slower rates.
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*
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* Example use:
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*
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* using namespace mbed::chrono_literals;
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*
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* ThisThread::sleep_for(5_ds);
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*/
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constexpr chrono::deciseconds operator "" _ds(unsigned long long x)
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{
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chrono::deciseconds::rep val = static_cast<chrono::deciseconds::rep>(x);
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assert(val >= 0 && static_cast<unsigned long long>(val) == x);
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return chrono::deciseconds(val);
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}
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/** User-defined literal for centiseconds (1/100 of a second)
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*
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* Useful in case we might change kernel tick frequency to be slower - with tick frequency 1000Hz, it is
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* possible to assign 500ms to a KernelClock::duration, but that would fail at slower rates.
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*
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* Example use:
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*
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* using namespace mbed::chrono_literals;
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*
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* ThisThread::sleep_for(1_cs);
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*/
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constexpr chrono::centiseconds operator "" _cs(unsigned long long x)
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{
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chrono::centiseconds::rep val = static_cast<chrono::centiseconds::rep>(x);
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assert(val >= 0 && static_cast<unsigned long long>(val) == x);
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return chrono::centiseconds(val);
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}
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} // inline namespace chrono_literals
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} // inline namespace literals
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namespace chrono {
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using namespace chrono_literals;
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} // namespace chrono
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} // namespace mbed
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/**@}*/
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/**@}*/
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#endif // __MBED_CHRONO_H__
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