Diff: mbed-os/events/equeue/equeue.h

Revision:

0:9fca2b23d0ba

--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/mbed-os/events/equeue/equeue.h	Sat Feb 23 12:13:36 2019 +0000
@@ -0,0 +1,223 @@
+
+/** \addtogroup events */
+/** @{*/
+/*
+ * Flexible event queue for dispatching events
+ *
+ * Copyright (c) 2016 Christopher Haster
+ *
+ * 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 EQUEUE_H
+#define EQUEUE_H
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+// Platform specific files
+#include "equeue/equeue_platform.h"
+
+#include <stddef.h>
+#include <stdint.h>
+
+
+// The minimum size of an event
+// This size is guaranteed to fit events created by event_call
+#define EQUEUE_EVENT_SIZE (sizeof(struct equeue_event) + 2*sizeof(void*))
+
+// Internal event structure
+struct equeue_event {
+    unsigned size;
+    uint8_t id;
+    uint8_t generation;
+
+    struct equeue_event *next;
+    struct equeue_event *sibling;
+    struct equeue_event **ref;
+
+    unsigned target;
+    int period;
+    void (*dtor)(void *);
+
+    void (*cb)(void *);
+    // data follows
+};
+
+// Event queue structure
+typedef struct equeue {
+    struct equeue_event *queue;
+    unsigned tick;
+    unsigned breaks;
+    uint8_t generation;
+
+    unsigned char *buffer;
+    unsigned npw2;
+    void *allocated;
+
+    struct equeue_event *chunks;
+    struct equeue_slab {
+        size_t size;
+        unsigned char *data;
+    } slab;
+
+    struct equeue_background {
+        bool active;
+        void (*update)(void *timer, int ms);
+        void *timer;
+    } background;
+
+    equeue_sema_t eventsema;
+    equeue_mutex_t queuelock;
+    equeue_mutex_t memlock;
+} equeue_t;
+
+
+// Queue lifetime operations
+//
+// Creates and destroys an event queue. The event queue either allocates a
+// buffer of the specified size with malloc or uses a user provided buffer
+// if constructed with equeue_create_inplace.
+//
+// If the event queue creation fails, equeue_create returns a negative,
+// platform-specific error code.
+int equeue_create(equeue_t *queue, size_t size);
+int equeue_create_inplace(equeue_t *queue, size_t size, void *buffer);
+void equeue_destroy(equeue_t *queue);
+
+// Dispatch events
+//
+// Executes events until the specified milliseconds have passed. If ms is
+// negative, equeue_dispatch will dispatch events indefinitely or until
+// equeue_break is called on this queue.
+//
+// When called with a finite timeout, the equeue_dispatch function is
+// guaranteed to terminate. When called with a timeout of 0, the
+// equeue_dispatch does not wait and is irq safe.
+void equeue_dispatch(equeue_t *queue, int ms);
+
+// Break out of a running event loop
+//
+// Forces the specified event queue's dispatch loop to terminate. Pending
+// events may finish executing, but no new events will be executed.
+void equeue_break(equeue_t *queue);
+
+// Simple event calls
+//
+// The specified callback will be executed in the context of the event queue's
+// dispatch loop. When the callback is executed depends on the call function.
+//
+// equeue_call       - Immediately post an event to the queue
+// equeue_call_in    - Post an event after a specified time in milliseconds
+// equeue_call_every - Post an event periodically every milliseconds
+//
+// All equeue_call functions are irq safe and can act as a mechanism for
+// moving events out of irq contexts.
+//
+// The return value is a unique id that represents the posted event and can
+// be passed to equeue_cancel. If there is not enough memory to allocate the
+// event, equeue_call returns an id of 0.
+int equeue_call(equeue_t *queue, void (*cb)(void *), void *data);
+int equeue_call_in(equeue_t *queue, int ms, void (*cb)(void *), void *data);
+int equeue_call_every(equeue_t *queue, int ms, void (*cb)(void *), void *data);
+
+// Allocate memory for events
+//
+// The equeue_alloc function allocates an event that can be manually dispatched
+// with equeue_post. The equeue_dealloc function may be used to free an event
+// that has not been posted. Once posted, an event's memory is managed by the
+// event queue and should not be deallocated.
+//
+// Both equeue_alloc and equeue_dealloc are irq safe.
+//
+// The equeue allocator is designed to minimize jitter in interrupt contexts as
+// well as avoid memory fragmentation on small devices. The allocator achieves
+// both constant-runtime and zero-fragmentation for fixed-size events, however
+// grows linearly as the quantity of different sized allocations increases.
+//
+// The equeue_alloc function returns a pointer to the event's allocated memory
+// and acts as a handle to the underlying event. If there is not enough memory
+// to allocate the event, equeue_alloc returns null.
+void *equeue_alloc(equeue_t *queue, size_t size);
+void equeue_dealloc(equeue_t *queue, void *event);
+
+// Configure an allocated event
+//
+// equeue_event_delay  - Millisecond delay before dispatching an event
+// equeue_event_period - Millisecond period for repeating dispatching an event
+// equeue_event_dtor   - Destructor to run when the event is deallocated
+void equeue_event_delay(void *event, int ms);
+void equeue_event_period(void *event, int ms);
+void equeue_event_dtor(void *event, void (*dtor)(void *));
+
+// Post an event onto the event queue
+//
+// The equeue_post function takes a callback and a pointer to an event
+// allocated by equeue_alloc. The specified callback will be executed in the
+// context of the event queue's dispatch loop with the allocated event
+// as its argument.
+//
+// The equeue_post function is irq safe and can act as a mechanism for
+// moving events out of irq contexts.
+//
+// The return value is a unique id that represents the posted event and can
+// be passed to equeue_cancel.
+int equeue_post(equeue_t *queue, void (*cb)(void *), void *event);
+
+// Cancel an in-flight event
+//
+// Attempts to cancel an event referenced by the unique id returned from
+// equeue_call or equeue_post. It is safe to call equeue_cancel after an event
+// has already been dispatched.
+//
+// The equeue_cancel function is irq safe.
+//
+// If called while the event queue's dispatch loop is active, equeue_cancel
+// does not guarantee that the event will not not execute after it returns as
+// the event may have already begun executing.
+void equeue_cancel(equeue_t *queue, int id);
+
+// Background an event queue onto a single-shot timer
+//
+// The provided update function will be called to indicate when the queue
+// should be dispatched. A negative timeout will be passed to the update
+// function when the timer is no longer needed.
+//
+// Passing a null update function disables the existing timer.
+//
+// The equeue_background function allows an event queue to take advantage
+// of hardware timers or even other event loops, allowing an event queue to
+// be effectively backgrounded.
+void equeue_background(equeue_t *queue,
+        void (*update)(void *timer, int ms), void *timer);
+
+// Chain an event queue onto another event queue
+//
+// After chaining a queue to a target, calling equeue_dispatch on the
+// target queue will also dispatch events from this queue. The queues
+// use their own buffers and events must be managed independently.
+//
+// Passing a null queue as the target will unchain the existing queue.
+//
+// The equeue_chain function allows multiple equeues to be composed, sharing
+// the context of a dispatch loop while still being managed independently.
+void equeue_chain(equeue_t *queue, equeue_t *target);
+
+
+#ifdef __cplusplus
+}
+#endif
+
+#endif
+
+/** @}*/