mbed-os/drivers/HighResClock.h

81 lines
2.5 KiB
C++

/* 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 */