px4_autopilot/platforms/common/uORB/Subscription.cpp

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/**
 * @file Subscription.cpp
 *
 */

#include "Subscription.hpp"
#include <px4_platform_common/defines.h>

namespace uORB
{

bool Subscription::subscribe()
{
	// check if already subscribed
	if (_node != nullptr) {
		return true;
	}

	if (_orb_id != ORB_ID::INVALID && uORB::Manager::get_instance()) {
		unsigned initial_generation;
		void *node = uORB::Manager::orb_add_internal_subscriber(_orb_id, _instance, &initial_generation);

		if (node) {
			_node = node;
			_last_generation = initial_generation;
			return true;
		}
	}

	return false;
}

void Subscription::unsubscribe()
{
	if (_node != nullptr) {
		uORB::Manager::orb_remove_internal_subscriber(_node);
	}

	_node = nullptr;
	_last_generation = 0;
}

bool Subscription::ChangeInstance(uint8_t instance)
{
	if (instance != _instance) {
		if (uORB::Manager::orb_device_node_exists(_orb_id, _instance)) {
			// if desired new instance exists, unsubscribe from current
			unsubscribe();
			_instance = instance;
			subscribe();
			return true;
		}

	} else {
		// already on desired index
		return true;
	}

	return false;
}

} // namespace uORB