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/**
 * @brief This module provides timer scheduling functionality for the 802.15.4 driver.
 *
 * Timer module should be used to implement strict timing features specified in IEEE 802.15.4 like:
 * * CSL,
 * * Timing out waiting for ACK frames,
 * * CSMA/CA,
 * * Inter-frame spacing: SIFS, LIFS (note that AIFS is implemented without using timer module).
 *
 * @note Current implementation supports only single one-shot timer. It may be extended to support
 *       timer scheduling and repetitive timers if needed.
 */

#ifndef NRF_802154_TIMER_SCHED_H_
#define NRF_802154_TIMER_SCHED_H_

#include <stdbool.h>
#include <stdint.h>

#ifdef __cplusplus
extern "C" {
#endif

/**
 * @defgroup nrf_802154_timer_sched Timer Scheduler module for the 802.15.4 driver
 * @{
 * @ingroup nrf_802154_timer_sched
 * @brief Timer Scheduler module for the 802.15.4 driver.
 *
 */

/**
 * @brief Type of function called when timer fires.
 *
 * @param[inout]  p_context  Pointer to user-defined memory location. May be NULL.
 */
typedef void (* nrf_802154_timer_callback_t)(void * p_context);

/**
 * @brief Type for driver instance.
 */
typedef struct nrf_802154_timer_s nrf_802154_timer_t;

/**
 * @brief Structure containing timer data used by timer module.
 */
struct nrf_802154_timer_s
{
    uint32_t                    t0;        ///< Base time of the timer [us]
    uint32_t                    dt;        ///< Timer expiration delta from @p t0 [us]
    nrf_802154_timer_callback_t callback;  ///< Callback function called when timer expires
    void                      * p_context; ///< User-defined context passed to callback function
    nrf_802154_timer_t        * p_next;    ///< A pointer to the next running timer
};

/**
 * @brief Initialize the timer scheduler.
 */
void nrf_802154_timer_sched_init(void);

/**
 * @brief Deinitialize the timer scheduler.
 */
void nrf_802154_timer_sched_deinit(void);

/**
 * @brief Get current time.
 *
 * This function is useful to set base time in @sa nrf_802154_timer_t structure.
 *
 * @return Current time in microseconds [us].
 */
uint32_t nrf_802154_timer_sched_time_get(void);

/**
 * @brief Get granularity of the timer that runs the timer scheduler.
 *
 * @return Granularity of the timer in microseconds [us].
 */
uint32_t nrf_802154_timer_sched_granularity_get(void);

/**
 * @brief Check if given time is in future.
 *
 * @param[in]  now  Current time. @sa nrf_802154_timer_sched_time_get()
 * @param[in]  t0   Base of time compared with @p now.
 * @param[in]  dt   Time delta from @p t0 compared with @p now.
 *
 * @retval true   Given time @p t0 @p dt is in future (compared to given @p now).
 * @retval false  Given time @p t0 @p dt is not in future (compared to given @p now).
 */
bool nrf_802154_timer_sched_time_is_in_future(uint32_t now, uint32_t t0, uint32_t dt);

/**
 * @brief Get timer time remaining to expiration.
 *
 * @param[in]  p_timer   Pointer to the timer to check remaining time.
 *
 * @retval remaining time [us] or 0 if timer has already expired.
 */
uint32_t nrf_802154_timer_sched_remaining_time_get(const nrf_802154_timer_t * p_timer);

/**
 * @brief Start given timer and add it to the scheduler.
 *
 * @note Fields t0, dt, callback and p_context should be filled in @p p_timer prior to calling this
 *       function; callback field cannot be NULL.
 *
 * @note Due to timer granularity the callback function cannot be called exactly at specified time.
 *       Use @p round_up to specify if given timer should be expired before or after time given in
 *       the @p p_timer structure. The dt field of the @p p_timer is updated with the rounded up value.
 *
 * @param[inout]  p_timer   Pointer to the timer to start and add to the scheduler.
 * @param[in]     round_up  True if timer should expire after specified time, false if it should
 *                          expire before.
 */
void nrf_802154_timer_sched_add(nrf_802154_timer_t * p_timer, bool round_up);

/**
 * @brief Stop given timer and remove it from the scheduler.
 *
 * @param[inout]  p_timer  Pointer to the timer to stop and remove from the scheduler.
 */
void nrf_802154_timer_sched_remove(nrf_802154_timer_t * p_timer);

/**
 * @brief Check if given timer is already scheduled.
 *
 * @param[in]  p_timer  Pointer to the timer to check.
 *
 * @retval true   Given timer is already scheduled.
 * @retval false  Given timer is not scheduled.
 */
bool nrf_802154_timer_sched_is_running(nrf_802154_timer_t * p_timer);

/**
 *@}
 **/

#ifdef __cplusplus
}
#endif

#endif /* NRF_802154_TIMER_SCHED_H_ */