Diff: drivers/internal/TaskBase.h

Revision:

1:9db0e321a9f4

diff -r 5b88d5760320 -r 9db0e321a9f4 drivers/internal/TaskBase.h
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/drivers/internal/TaskBase.h	Tue Dec 31 06:02:27 2019 +0000
@@ -0,0 +1,168 @@
+/*
+ * Copyright (c) 2018-2019, Arm Limited and affiliates.
+ * 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 TASK_BASE_H
+#define TASK_BASE_H
+
+#include "platform/Callback.h"
+#include "platform/mbed_assert.h"
+#include "LinkEntry.h"
+
+namespace rtos {
+class Semaphore;
+}
+
+namespace events {
+
+class TaskQueue;
+
+/**
+ * \defgroup drivers_TaskBase TaskBase class
+ * \ingroup drivers-internal-api-usb
+ * @{
+ */
+
+/** TaskBase
+ *
+ *  Representation of a caller allocated task
+ */
+class TaskBase : public LinkEntry {
+public:
+
+    typedef void (*run_callback_t)(void *data);
+
+    /**
+     * Construct a new TaskBase object
+     *
+     * @param q Queue for posting to
+     */
+    TaskBase(TaskQueue *q);
+
+    /**
+     * Destroy this TaskBase
+     */
+    virtual ~TaskBase();
+
+    /**
+     * Set the queue of this task
+     *
+     * @param q TaskQueue to post to
+     */
+    void set(TaskQueue *q);
+
+    /**
+     * Cancel the execution of this task
+     *
+     * Once cancelled the task can be posted again. Previous
+     * calls to post may still run. If you need to ensure the
+     * callback has finished the function wait() can be used.
+     *
+     * @note This function is interrupt safe
+     */
+    void cancel();
+
+    /**
+     * Return true if this task is ready to be posted
+     *
+     * Check if this task is on a queue waiting to be run.
+     *
+     * @return true if it is safe to call post
+     */
+    bool ready();
+
+    /**
+     * Wait for this task to finish execution
+     *
+     * When this function returns then this task is in the finished state.
+     */
+    void wait();
+
+    /**
+     * Check if the callback has run to completion or been fully canceled
+     *
+     * When an task is finished the queue is completely done with it and the
+     * callback is either fully complete or has been canceled and will not run.
+     *
+     * @return true if this task has been flushed from the queue, false otherwise
+     */
+    bool finished();
+
+protected:
+
+    /**
+     * Size of buffer required for TaskBase::start
+     *
+     * @return requested buffer size
+     */
+    virtual uint32_t size() = 0;
+
+    /**
+     * Copy any callback data and return a callback to run
+     *
+     * @param data Buffer to copy data to. Do not copy more than TaskBase::size() data.
+     * @param size Maximum size to copy
+     */
+    virtual run_callback_t start(void *data, uint32_t size) = 0;
+
+    /**
+     * Inform this task that execution has finished.
+     *
+     */
+    virtual void finish();
+
+    /**
+     * Post this task to the set TaskQueue for execution
+     */
+    void post();
+
+private:
+
+    TaskQueue *_queue;
+    bool _posted;
+    uint16_t _start_count;
+    rtos::Semaphore *_flush_sem;
+
+    friend class TaskQueue;
+
+    /*
+     * Must be called in a critical section
+     *
+     * This function should not be called directly. Instead
+     * TaskQueue::task_start should be used instead.
+     */
+    run_callback_t _start(void *buffer, uint32_t size);
+
+    /*
+     * Must be called in a critical section
+     *
+     * This function should not be called directly. Instead
+     * TaskQueue::task_finish should be used instead.
+     *
+     */
+    void _finish();
+
+    /*
+     * Unblock wait if this task is finished
+     */
+    void _wake_check();
+};
+
+/** @}*/
+
+}
+
+#endif