Function esp_idf_svc::sys::esp_event_handler_register

pub unsafe extern "C" fn esp_event_handler_register(
    event_base: *const i8,
    event_id: i32,
    event_handler: Option<unsafe extern "C" fn(_: *mut c_void, _: *const i8, _: i32, _: *mut c_void)>,
    event_handler_arg: *mut c_void,
) -> i32

@brief Register an event handler to the system event loop (legacy).

This function can be used to register a handler for either: (1) specific events, (2) all events of a certain event base, or (3) all events known by the system event loop.

• specific events: specify exact event_base and event_id
• all events of a certain base: specify exact event_base and use ESP_EVENT_ANY_ID as the event_id
• all events known by the loop: use ESP_EVENT_ANY_BASE for event_base and ESP_EVENT_ANY_ID as the event_id

Registering multiple handlers to events is possible. Registering a single handler to multiple events is also possible. However, registering the same handler to the same event multiple times would cause the previous registrations to be overwritten.

@param[in] event_base the base ID of the event to register the handler for @param[in] event_id the ID of the event to register the handler for @param[in] event_handler the handler function which gets called when the event is dispatched @param[in] event_handler_arg data, aside from event data, that is passed to the handler when it is called

@note the event loop library does not maintain a copy of event_handler_arg, therefore the user should ensure that event_handler_arg still points to a valid location by the time the handler gets called

@return

• ESP_OK: Success
• ESP_ERR_NO_MEM: Cannot allocate memory for the handler
• ESP_ERR_INVALID_ARG: Invalid combination of event base and event ID
• Others: Fail