Diff: mbed-os/events/mbed_shared_queues.h

Revision:

0:9b3d4731edbb

--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/mbed-os/events/mbed_shared_queues.h	Thu Jun 21 13:51:43 2018 +0000
@@ -0,0 +1,92 @@
+
+/** \addtogroup events */
+/** @{*/
+/* events
+ * Copyright (c) 2017 ARM Limited
+ *
+ * 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_SHARED_QUEUES_H
+#define MBED_SHARED_QUEUES_H
+
+#include "events/EventQueue.h"
+
+namespace mbed {
+
+/**
+ * Return a pointer to an EventQueue, on which normal tasks can be queued.
+ *
+ * All calls to this return the same EventQueue - it and its dispatch thread
+ * are created on the first call to this function. The dispatch thread
+ * runs at default priority (currently osPriorityNormal).
+ *
+ * The EventQueue returned may be used to call() Events, or to chain() other
+ * EventQueues so that they are run in the same context.
+ *
+ * Events (or chained EventQueues) executing on the normal event queue should
+ * normally take less than 10ms to execute, to avoid starving other users. As
+ * such, users can expect that event latency will typically be 10ms or less,
+ * but could occasionally be significantly higher if many events are queued.
+ *
+ * If an RTOS is not present or the configuration option
+ * `events.shared-dispatch-from-application` is set to true, then this
+ * does not create a dedicated dispatch thread - instead the application is
+ * expected to run the EventQueue's dispatch, eg from main. This is necessary
+ * for the event loop to work without an RTOS, or an RTOS system can can save
+ * memory by reusing the main stack.
+ *
+ * @note
+ * mbed_event_queue is not itself IRQ safe. To use the mbed_event_queue in
+ * interrupt context, you must first call `mbed_event_queue()` in threaded
+ * context and store the pointer for later use.
+ *
+ * @return pointer to event queue
+ */
+events::EventQueue *mbed_event_queue();
+
+#ifdef MBED_CONF_RTOS_PRESENT
+/**
+ * Return a pointer to an EventQueue, on which small high-priority tasks can
+ * be queues, such as simple deferrals from interrupt.
+ *
+ * All calls to this return the same EventQueue - it and its thread are
+ * created on the first call to this function. The dispatch thread
+ * runs at a high priority (currently osPriorityHigh).
+ *
+ * The EventQueue returned may be used to call() Events, or to chain() other
+ * EventQueues so that they are run in the same context.
+ *
+ * Events (or chained EventQueues) executing on the high-priority event queue
+ * should normally take less than 100us to execute, to avoid starving other
+ * users. As such, users can expect that event latency will typically be 100us
+ * or less, but could occasionally be significantly higher if many events are
+ * queued.
+ *
+ * @note
+ * mbed_highprio_event_queue is not itself IRQ safe. To use the
+ * mbed_highprio_event_queue in interrupt context, you must first call
+ * `mbed_event_queue()` in threaded context and store the pointer for
+ * later use.
+ *
+ * @return pointer to high-priority event queue
+ */
+
+events::EventQueue *mbed_highprio_event_queue();
+
+#endif // MBED_CONF_RTOS_PRESENT
+
+};
+
+#endif
+
+/** @}*/