Notifier.h

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// Copyright (c) FIRST and other WPILib contributors.
// Open Source Software; you can modify and/or share it under the terms of
// the WPILib BSD license file in the root directory of this project.
 
#pragma once
 
#include <stdint.h>
 
#include <wpi/nodiscard.h>
 
#include "hal/Types.h"
 
/**
 * @defgroup hal_notifier Notifier Functions
 * @ingroup hal_capi
 * @{
 */
 
#ifdef __cplusplus
extern "C" {
#endif
 
/**
 * Initializes a notifier.
 *
 * A notifier is an FPGA controller timer that triggers at requested intervals
 * based on the FPGA time. This can be used to make precise control loops.
 *
 * @param[out] status Error status variable. 0 on success.
 * @return the created notifier
 */
HAL_NotifierHandle HAL_InitializeNotifier(int32_t* status);
 
/**
 * Sets the HAL notifier thread priority.
 *
 * The HAL notifier thread is responsible for managing the FPGA's notifier
 * interrupt and waking up user's Notifiers when it's their time to run.
 * Giving the HAL notifier thread real-time priority helps ensure the user's
 * real-time Notifiers, if any, are notified to run in a timely manner.
 *
 * @param[in] realTime Set to true to set a real-time priority, false for
 *                     standard priority.
 * @param[in] priority Priority to set the thread to. For real-time, this is
 *                     1-99 with 99 being highest. For non-real-time, this is
 *                     forced to 0. See "man 7 sched" for more details.
 * @param[out] status  Error status variable. 0 on success.
 * @return True on success.
 */
HAL_Bool HAL_SetNotifierThreadPriority(HAL_Bool realTime, int32_t priority,
                                       int32_t* status);
 
/**
 * Sets the name of a notifier.
 *
 * @param[in] notifierHandle the notifier handle
 * @param[in] name name
 * @param[out] status Error status variable. 0 on success.
 */
void HAL_SetNotifierName(HAL_NotifierHandle notifierHandle, const char* name,
                         int32_t* status);
 
/**
 * Stops a notifier from running.
 *
 * This will cause any call into HAL_WaitForNotifierAlarm to return with time =
 * 0.
 *
 * @param[in] notifierHandle the notifier handle
 * @param[out] status Error status variable. 0 on success.
 */
void HAL_StopNotifier(HAL_NotifierHandle notifierHandle, int32_t* status);
 
/**
 * Cleans a notifier.
 *
 * Note this also stops a notifier if it is already running.
 *
 * @param[in] notifierHandle the notifier handle
 * @param[out] status Error status variable. 0 on success.
 */
void HAL_CleanNotifier(HAL_NotifierHandle notifierHandle, int32_t* status);
 
/**
 * Updates the trigger time for a notifier.
 *
 * Note that this time is an absolute time relative to HAL_GetFPGATime()
 *
 * @param[in] notifierHandle the notifier handle
 * @param[in] triggerTime    the updated trigger time
 * @param[out] status        Error status variable. 0 on success.
 */
void HAL_UpdateNotifierAlarm(HAL_NotifierHandle notifierHandle,
                             uint64_t triggerTime, int32_t* status);
 
/**
 * Cancels the next notifier alarm.
 *
 * This does not cause HAL_WaitForNotifierAlarm to return.
 *
 * @param[in] notifierHandle the notifier handle
 * @param[out] status Error status variable. 0 on success.
 */
void HAL_CancelNotifierAlarm(HAL_NotifierHandle notifierHandle,
                             int32_t* status);
 
/**
 * Waits for the next alarm for the specific notifier.
 *
 * This is a blocking call until either the time elapses or HAL_StopNotifier
 * gets called. If the latter occurs, this function will return zero and any
 * loops using this function should exit. Failing to do so can lead to
 * use-after-frees.
 *
 * @param[in] notifierHandle the notifier handle
 * @param[out] status        Error status variable. 0 on success.
 * @return the FPGA time the notifier returned
 */
WPI_NODISCARD
uint64_t HAL_WaitForNotifierAlarm(HAL_NotifierHandle notifierHandle,
                                  int32_t* status);
 
#ifdef __cplusplus
}  // extern "C"
#endif
/** @} */