Subscription.cpp
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/****************************************************************************
*
* Copyright (c) 2012-2019 PX4 Development Team. All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
*
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in
* the documentation and/or other materials provided with the
* distribution.
* 3. Neither the name PX4 nor the names of its contributors may be
* used to endorse or promote products derived from this software
* without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
* "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
* LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
* FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
* COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
* INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
* BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS
* OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
* AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
* ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
* POSSIBILITY OF SUCH DAMAGE.
*
****************************************************************************/
/**
* @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) {
DeviceMaster *device_master = uORB::Manager::get_instance()->get_device_master();
if (device_master != nullptr) {
if (!device_master->deviceNodeExists(_orb_id, _instance)) {
return false;
}
uORB::DeviceNode *node = device_master->getDeviceNode(get_topic(), _instance);
if (node != nullptr) {
_node = node;
_node->add_internal_subscriber();
_last_generation = _node->get_initial_generation();
return true;
}
}
}
return false;
}
void Subscription::unsubscribe()
{
if (_node != nullptr) {
_node->remove_internal_subscriber();
}
_node = nullptr;
_last_generation = 0;
}
bool Subscription::ChangeInstance(uint8_t instance)
{
if (instance != _instance) {
DeviceMaster *device_master = uORB::Manager::get_instance()->get_device_master();
if (device_master != nullptr) {
if (!device_master->deviceNodeExists(_orb_id, _instance)) {
return false;
}
// 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