Task.h

/*
 * Copyright (C) 2018 Lakoja on github.com
 *
 * 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 __RTOS_TASK_WRAPPER_H__
#define __RTOS_TASK_WRAPPER_H__

class Task
{

private:
  xTaskHandle taskHandle;
  bool isTasked = false;

public:
  void start(String name, UBaseType_t uxPriority = 1, uint16_t stackSize = 5000)
  {
    isTasked = true;
    // TODO what is a reasonable stack size?
    ::xTaskCreate(&runTask, name.c_str(), stackSize, this, uxPriority, &taskHandle);
    // TODO could also use ..PinnedToCore(... tskNO_AFFINITY);
  }

  virtual void run() = 0;
  
protected:
  // TODO what is the difference to delay() and yield()? Is this necessary?
  void delay(uint16_t ms)
  {
    if (isTasked)
      ::vTaskDelay(ms / portTICK_PERIOD_MS);
    else
      delay(ms);
  }

  void yield()
  {
    if (isTasked)
      taskYIELD();
    else
      yield();
  }

  void sleepAfterLoop(uint16_t maxMillis, uint32_t loopStart)
  {
    int32_t sleepNow = maxMillis - (millis() - loopStart);
    if (sleepNow >= 0)
      delay(sleepNow);
    else
      yield(); 
  }

private:
  static void runTask(void *pTaskInstance)
  {
    Task* pTask = (Task*)pTaskInstance;
    pTask->run();
    pTask->cleanup();
  }

  void cleanup()
  {
    ::vTaskDelete(taskHandle);
  }
};

#endif