Mbed OS Reference | HighResClock.h Source File

 /* mbed Microcontroller Library
  * Copyright (c) 2006-2019 ARM Limited
  * SPDX-License-Identifier: Apache-2.0
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
  * You may obtain a copy of the License at
  *
  *     http://www.apache.org/licenses/LICENSE-2.0
  *
  * Unless required by applicable law or agreed to in writing, software
  * distributed under the License is distributed on an "AS IS" BASIS,
  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
  * See the License for the specific language governing permissions and
  * limitations under the License.
  */
 #ifndef MBED_HIGHRESCLOCK_H
 #define MBED_HIGHRESCLOCK_H
 
 #include <chrono>
 #include "hal/us_ticker_api.h"
 #include "platform/mbed_power_mgmt.h"
 
 namespace mbed {
 /**
  * \defgroup drivers_HighResClock HighResClock class
  * \ingroup drivers-public-api-ticker
  * @{
  */
 
 /**
  * A C++11 Clock representing the HAL us_ticker.
  *
  * The high resolution clock will pause whenever deep sleep is entered.
  *
  * Lock and unlock methods are provided to control deep sleep to keep the
  * clock running. LowPowerClock provides the same methods as dummies to support
  * generic code that works with either clock.
  *
  * Locks and unlocks are passed to the deep sleep manager, so are reference counted.
  *
  * The lock and unlock methods mean this is a C++11 BasicLockable class,
  * so scoped_lock<HighResClock> or unique_lock<HighResClock> could be used to
  * manage ownership and guarantee balanced unlocking.
  *
  * @note To avoid the need to worry about locking, consider using the Timer, Ticker or
  *       Timeout classes, which lock automatically and only whenever they are active
  */
 class HighResClock {
 public:
     /* duration is C++11 standard microseconds, so representation will be 64-bit signed integer */
     using duration = std::chrono::microseconds;
     using rep = duration::rep;
     using period = duration::period;
     using time_point = std::chrono::time_point<HighResClock>;
     static const bool is_steady = false;
 
     /** Read the current time */
     static time_point now()
     {
         return time_point{duration{ticker_read_us(get_us_ticker_data())}};
     }
 
     /** Lock the clock to ensure it stays running */
     static void lock()
     {
         sleep_manager_lock_deep_sleep();
     }
 
     /** Unlock the clock, allowing it to stop during power saving */
     static void unlock()
     {
         sleep_manager_unlock_deep_sleep();
     }
 };
 
 /** @}*/
 
 }
 #endif /* MBED_HIGHRESCLOCK_H */
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