text: /**
   * Copyright (c) 2012 - 2021, Nordic Semiconductor ASA
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  /** @file
   *
   * @defgroup app_scheduler Scheduler
   * @{
   * @ingroup app_common
   *
   * @brief The scheduler is used for transferring execution from the interrupt context to the main
   *        context.
   *
   * @details See @ref seq_diagrams_sched for sequence diagrams illustrating the flow of events
   *          when using the Scheduler.
   *
   * @section app_scheduler_req Requirements:
   *
   * @subsection main_context_logic Logic in main context:
   *
   *   - Define an event handler for each type of event expected.
   *   - Initialize the scheduler by calling the APP_SCHED_INIT() macro before entering the
   *     application main loop.
   *   - Call app_sched_execute() from the main loop each time the application wakes up because of an
   *     event (typically when sd_app_evt_wait() returns).
   *
   * @subsection int_context_logic Logic in interrupt context:
   *
   *   - In the interrupt handler, call app_sched_event_put()
   *     with the appropriate data and event handler. This will insert an event into the
   *     scheduler's queue. The app_sched_execute() function will pull this event and call its
   *     handler in the main context.
   *
   * @if (PERIPHERAL)
   * For an example usage of the scheduler, see the implementations of
   * @ref ble_sdk_app_hids_mouse and @ref ble_sdk_app_hids_keyboard.
   * @endif
   *
   * @image html scheduler_working.svg The high level design of the scheduler
   */
  
  #ifndef APP_SCHEDULER_H__
  #define APP_SCHEDULER_H__
  
  #include "sdk_config.h"
  #include <stdint.h>
  #include "app_error.h"
  #include "app_util.h"
  
  #ifdef __cplusplus
  extern "C" {
  #endif
  
  #define APP_SCHED_EVENT_HEADER_SIZE 8       /**< Size of app_scheduler.event_header_t (only for use inside APP_SCHED_BUF_SIZE()). */
  
  /**@brief Compute number of bytes required to hold the scheduler buffer.
   *
   * @param[in] EVENT_SIZE   Maximum size of events to be passed through the scheduler.
   * @param[in] QUEUE_SIZE   Number of entries in scheduler queue (i.e. the maximum number of events
   *                         that can be scheduled for execution).
   *
   * @return    Required scheduler buffer size (in bytes).
   */
  #define APP_SCHED_BUF_SIZE(EVENT_SIZE, QUEUE_SIZE)                                                 \
              (((EVENT_SIZE) + APP_SCHED_EVENT_HEADER_SIZE) * ((QUEUE_SIZE) + 1))
  
  /**@brief Scheduler event handler type. */
  typedef void (*app_sched_event_handler_t)(void * p_event_data, uint16_t event_size);
  
  /**@brief Macro for initializing the event scheduler.
   *
   * @details It will also handle dimensioning and allocation of the memory buffer required by the
   *          scheduler, making sure the buffer is correctly aligned.
   *
   * @param[in] EVENT_SIZE   Maximum size of events to be passed through the scheduler.
   * @param[in] QUEUE_SIZE   Number of entries in scheduler queue (i.e. the maximum number of events
   *                         that can be scheduled for execution).
   *
   * @note Since this macro allocates a buffer, it must only be called once (it is OK to call it
   *       several times as long as it is from the same location, e.g. to do a reinitialization).
   */
  #define APP_SCHED_INIT(EVENT_SIZE, QUEUE_SIZE)                                                     \
      do                                                                                             \
      {                                                                                              \
          static uint32_t APP_SCHED_BUF[CEIL_DIV(APP_SCHED_BUF_SIZE((EVENT_SIZE), (QUEUE_SIZE)),     \
                                                 sizeof(uint32_t))];                                 \
          uint32_t ERR_CODE = app_sched_init((EVENT_SIZE), (QUEUE_SIZE), APP_SCHED_BUF);             \
          APP_ERROR_CHECK(ERR_CODE);                                                                 \
      } while (0)
  
  /**@brief Function for initializing the Scheduler.
   *
   * @details It must be called before entering the main loop.
   *
   * @param[in]   max_event_size   Maximum size of events to be passed through the scheduler.
   * @param[in]   queue_size       Number of entries in scheduler queue (i.e. the maximum number of
   *                               events that can be scheduled for execution).
   * @param[in]   p_evt_buffer   Pointer to memory buffer for holding the scheduler queue. It must
   *                               be dimensioned using the APP_SCHED_BUFFER_SIZE() macro. The buffer
   *                               must be aligned to a 4 byte boundary.
   *
   * @note Normally initialization should be done using the APP_SCHED_INIT() macro, as that will both
   *       allocate the scheduler buffer, and also align the buffer correctly.
   *
   * @retval      NRF_SUCCESS               Successful initialization.
   * @retval      NRF_ERROR_INVALID_PARAM   Invalid parameter (buffer not aligned to a 4 byte
   *                                        boundary).
   */
  uint32_t app_sched_init(uint16_t max_event_size, uint16_t queue_size, void * p_evt_buffer);
  
  /**@brief Function for executing all scheduled events.
   *
   * @details This function must be called from within the main loop. It will execute all events
   *          scheduled since the last time it was called.
   */
  void app_sched_execute(void);
  
  /**@brief Function for scheduling an event.
   *
   * @details Puts an event into the event queue.
   *
   * @param[in]   p_event_data   Pointer to event data to be scheduled.
   * @param[in]   event_size     Size of event data to be scheduled.
   * @param[in]   handler        Event handler to receive the event.
   *
   * @return      NRF_SUCCESS on success, otherwise an error code.
   */
  uint32_t app_sched_event_put(void const *              p_event_data,
                               uint16_t                  event_size,
                               app_sched_event_handler_t handler);
  
  /**@brief Function for getting the maximum observed queue utilization.
   *
   * Function for tuning the module and determining QUEUE_SIZE value and thus module RAM usage.
   *
   * @note @ref APP_SCHEDULER_WITH_PROFILER must be enabled to use this functionality.
   *
   * @return Maximum number of events in queue observed so far.
   */
  uint16_t app_sched_queue_utilization_get(void);
  
  /**@brief Function for getting the current amount of free space in the queue.
   *
   * @details The real amount of free space may be less if entries are being added from an interrupt.
   *          To get the sxact value, this function should be called from the critical section.
   *
   * @return Amount of free space in the queue.
   */
  uint16_t app_sched_queue_space_get(void);
  
  /**@brief A function to pause the scheduler.
   *
   * @details When the scheduler is paused events are not pulled from the scheduler queue for
   *          processing. The function can be called multiple times. To unblock the scheduler the
   *          function @ref app_sched_resume has to be called the same number of times.
   *
   * @note @ref APP_SCHEDULER_WITH_PAUSE must be enabled to use this functionality.
   */
  void app_sched_pause(void);
  
  /**@brief A function to resume a scheduler.
   *
   * @details To unblock the scheduler this function has to be called the same number of times as
   *          @ref app_sched_pause function.
   *
   * @note @ref APP_SCHEDULER_WITH_PAUSE must be enabled to use this functionality.
   */
  void app_sched_resume(void);
  
  #ifdef __cplusplus
  }
  #endif
  
  #endif // APP_SCHEDULER_H__
  
  /** @} */
  