mirror of https://github.com/ARMmbed/mbed-os.git
93 lines
3.3 KiB
C++
93 lines
3.3 KiB
C++
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/** \addtogroup events */
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/** @{*/
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/* events
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* Copyright (c) 2017 ARM Limited
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*
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* Licensed under the Apache License, Version 2.0 (the "License");
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* you may 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,
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* WITHOUT 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_SHARED_QUEUES_H
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#define MBED_SHARED_QUEUES_H
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#include "events/EventQueue.h"
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namespace mbed {
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/**
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* Return a pointer to an EventQueue, on which normal tasks can be queued.
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*
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* All calls to this return the same EventQueue - it and its dispatch thread
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* are created on the first call to this function. The dispatch thread
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* runs at default priority (currently osPriorityNormal).
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*
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* The EventQueue returned may be used to call() Events, or to chain() other
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* EventQueues so that they are run in the same context.
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*
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* Events (or chained EventQueues) executing on the normal event queue should
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* normally take less than 10ms to execute, to avoid starving other users. As
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* such, users can expect that event latency will typically be 10ms or less,
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* but could occasionally be significantly higher if many events are queued.
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*
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* If an RTOS is not present or the configuration option
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* `events.shared-dispatch-from-application` is set to true, then this
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* does not create a dedicated dispatch thread - instead the application is
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* expected to run the EventQueue's dispatch, eg from main. This is necessary
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* for the event loop to work without an RTOS, or an RTOS system can can save
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* memory by reusing the main stack.
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*
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* @note
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* mbed_event_queue is not itself IRQ safe. To use the mbed_event_queue in
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* interrupt context, you must first call `mbed_event_queue()` in threaded
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* context and store the pointer for later use.
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*
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* @return pointer to event queue
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*/
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events::EventQueue *mbed_event_queue();
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#ifdef MBED_CONF_RTOS_PRESENT
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/**
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* Return a pointer to an EventQueue, on which small high-priority tasks can
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* be queues, such as simple deferrals from interrupt.
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*
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* All calls to this return the same EventQueue - it and its thread are
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* created on the first call to this function. The dispatch thread
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* runs at a high priority (currently osPriorityHigh).
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*
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* The EventQueue returned may be used to call() Events, or to chain() other
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* EventQueues so that they are run in the same context.
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*
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* Events (or chained EventQueues) executing on the high-priority event queue
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* should normally take less than 100us to execute, to avoid starving other
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* users. As such, users can expect that event latency will typically be 100us
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* or less, but could occasionally be significantly higher if many events are
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* queued.
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*
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* @note
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* mbed_highprio_event_queue is not itself IRQ safe. To use the
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* mbed_highprio_event_queue in interrupt context, you must first call
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* `mbed_event_queue()` in threaded context and store the pointer for
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* later use.
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*
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* @return pointer to high-priority event queue
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*/
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events::EventQueue *mbed_highprio_event_queue();
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#endif // MBED_CONF_RTOS_PRESENT
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};
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#endif
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/** @}*/
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