text: /****************************************************************************
   *
   *   Copyright (c) 2016 PX4 Development Team. All rights reserved.
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   * Redistribution and use in source and binary forms, with or without
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   * 1. Redistributions of source code must retain the above copyright
   *    notice, this list of conditions and the following disclaimer.
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   *    used to endorse or promote products derived from this software
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   ****************************************************************************/
  
  /**
   * @file mavlink_ulog.cpp
   * ULog data streaming via MAVLink
   *
   * @author Beat Küng <beat-kueng@gmx.net>
   */
  
  #include "mavlink_ulog.h"
  #include <px4_log.h>
  #include <errno.h>
  #include <mathlib/mathlib.h>
  
  bool MavlinkULog::_init = false;
  MavlinkULog *MavlinkULog::_instance = nullptr;
  px4_sem_t MavlinkULog::_lock;
  const float MavlinkULog::_rate_calculation_delta_t = 0.1f;
  
  
  MavlinkULog::MavlinkULog(int datarate, float max_rate_factor, uint8_t target_system, uint8_t target_component)
  	: _target_system(target_system), _target_component(target_component),
  	  _max_rate_factor(max_rate_factor),
  	  _max_num_messages(math::max(1, (int)ceilf(_rate_calculation_delta_t *_max_rate_factor * datarate /
  				      (MAVLINK_MSG_ID_LOGGING_DATA_LEN + MAVLINK_NUM_NON_PAYLOAD_BYTES)))),
  	  _current_rate_factor(max_rate_factor)
  {
  	// make sure we won't read any old messages
  	while (_ulog_stream_sub.update()) {
  
  <<<<<<< HEAD
  =======
  	if (_ulog_stream_sub < 0) {
  		PX4_ERR("orb_subscribe failed (%i)", errno);
  
  	} else {
  		// make sure we won't read any old messages
  		struct ulog_stream_s stream_msg;
  		bool update;
  
  		while (orb_check(_ulog_stream_sub, &update) == 0 && update) {
  			orb_copy(ORB_ID(ulog_stream), _ulog_stream_sub, &stream_msg);
  		}
  >>>>>>> f13bbacd5277123d6af2cb5ed21587c220031353
  	}
  
  	_waiting_for_initial_ack = true;
  	_last_sent_time = hrt_absolute_time(); //(ab)use this timestamp during initialization
  	_next_rate_check = _last_sent_time + _rate_calculation_delta_t * 1.e6f;
  }
  
  MavlinkULog::~MavlinkULog()
  {
  	if (_ulog_stream_ack_pub) {
  		orb_unadvertise(_ulog_stream_ack_pub);
  	}
  }
  
  void MavlinkULog::start_ack_received()
  {
  	if (_waiting_for_initial_ack) {
  		_last_sent_time = 0;
  		_waiting_for_initial_ack = false;
  		PX4_DEBUG("got logger ack");
  	}
  }
  
  int MavlinkULog::handle_update(mavlink_channel_t channel)
  {
  	static_assert(sizeof(ulog_stream_s::data) == MAVLINK_MSG_LOGGING_DATA_FIELD_DATA_LEN,
  		      "Invalid uorb ulog_stream.data length");
  	static_assert(sizeof(ulog_stream_s::data) == MAVLINK_MSG_LOGGING_DATA_ACKED_FIELD_DATA_LEN,
  		      "Invalid uorb ulog_stream.data length");
  
  	if (_waiting_for_initial_ack) {
  		if (hrt_elapsed_time(&_last_sent_time) > 3e5) {
  			PX4_WARN("no ack from logger (is it running?)");
  			return -1;
  		}
  
  		return 0;
  	}
  
  	// check if we're waiting for an ACK
  	if (_last_sent_time) {
  		bool check_for_updates = false;
  
  		if (_ack_received) {
  			_last_sent_time = 0;
  			check_for_updates = true;
  
  		} else {
  
  			if (hrt_elapsed_time(&_last_sent_time) > ulog_stream_ack_s::ACK_TIMEOUT * 1000) {
  				if (++_sent_tries > ulog_stream_ack_s::ACK_MAX_TRIES) {
  					return -ETIMEDOUT;
  
  				} else {
  					PX4_DEBUG("re-sending ulog mavlink message (try=%i)", _sent_tries);
  					_last_sent_time = hrt_absolute_time();
  
  					const ulog_stream_s &ulog_data = _ulog_stream_sub.get();
  
  					mavlink_logging_data_acked_t msg;
  					msg.sequence = ulog_data.sequence;
  					msg.length = ulog_data.length;
  					msg.first_message_offset = ulog_data.first_message_offset;
  					msg.target_system = _target_system;
  					msg.target_component = _target_component;
  					memcpy(msg.data, ulog_data.data, sizeof(msg.data));
  					mavlink_msg_logging_data_acked_send_struct(channel, &msg);
  				}
  			}
  		}
  
  		if (!check_for_updates) {
  			return 0;
  		}
  	}
  
  	while ((_current_num_msgs < _max_num_messages) && _ulog_stream_sub.update()) {
  		const ulog_stream_s &ulog_data = _ulog_stream_sub.get();
  
  		if (ulog_data.timestamp > 0) {
  			if (ulog_data.flags & ulog_stream_s::FLAGS_NEED_ACK) {
  				_sent_tries = 1;
  				_last_sent_time = hrt_absolute_time();
  				lock();
  				_wait_for_ack_sequence = ulog_data.sequence;
  				_ack_received = false;
  				unlock();
  
  				mavlink_logging_data_acked_t msg;
  				msg.sequence = ulog_data.sequence;
  				msg.length = ulog_data.length;
  				msg.first_message_offset = ulog_data.first_message_offset;
  				msg.target_system = _target_system;
  				msg.target_component = _target_component;
  				memcpy(msg.data, ulog_data.data, sizeof(msg.data));
  				mavlink_msg_logging_data_acked_send_struct(channel, &msg);
  
  			} else {
  				mavlink_logging_data_t msg;
  				msg.sequence = ulog_data.sequence;
  				msg.length = ulog_data.length;
  				msg.first_message_offset = ulog_data.first_message_offset;
  				msg.target_system = _target_system;
  				msg.target_component = _target_component;
  				memcpy(msg.data, ulog_data.data, sizeof(msg.data));
  				mavlink_msg_logging_data_send_struct(channel, &msg);
  			}
  		}
  
  		++_current_num_msgs;
  	}
  
  	//need to update the rate?
  	hrt_abstime t = hrt_absolute_time();
  
  	if (t > _next_rate_check) {
  		if (_current_num_msgs < _max_num_messages) {
  			_current_rate_factor = _max_rate_factor * (float)_current_num_msgs / _max_num_messages;
  
  		} else {
  			_current_rate_factor = _max_rate_factor;
  		}
  
  		_current_num_msgs = 0;
  		_next_rate_check = t + _rate_calculation_delta_t * 1.e6f;
  		PX4_DEBUG("current rate=%.3f (max=%i msgs in %.3fs)", (double)_current_rate_factor, _max_num_messages,
  			  (double)_rate_calculation_delta_t);
  	}
  
  	return 0;
  }
  
  void MavlinkULog::initialize()
  {
  	if (_init) {
  		return;
  	}
  
  	px4_sem_init(&_lock, 1, 1);
  	_init = true;
  }
  
  MavlinkULog *MavlinkULog::try_start(int datarate, float max_rate_factor, uint8_t target_system,
  				    uint8_t target_component)
  {
  	MavlinkULog *ret = nullptr;
  	bool failed = false;
  	lock();
  
  	if (!_instance) {
  		ret = _instance = new MavlinkULog(datarate, max_rate_factor, target_system, target_component);
  
  		if (!_instance) {
  			failed = true;
  		}
  	}
  
  	unlock();
  
  	if (failed) {
  		PX4_ERR("alloc failed");
  	}
  
  	return ret;
  }
  
  void MavlinkULog::stop()
  {
  	lock();
  
  	if (_instance) {
  		delete _instance;
  		_instance = nullptr;
  	}
  
  	unlock();
  }
  
  void MavlinkULog::handle_ack(mavlink_logging_ack_t ack)
  {
  	lock();
  
  	if (_instance) { // make sure stop() was not called right before
  		if (_wait_for_ack_sequence == ack.sequence) {
  			_ack_received = true;
  			publish_ack(ack.sequence);
  		}
  	}
  
  	unlock();
  }
  
  void MavlinkULog::publish_ack(uint16_t sequence)
  {
  	ulog_stream_ack_s ack;
  	ack.timestamp = hrt_absolute_time();
  	ack.sequence = sequence;
  
  	if (_ulog_stream_ack_pub == nullptr) {
  		_ulog_stream_ack_pub = orb_advertise(ORB_ID(ulog_stream_ack), &ack);
  
  	} else {
  		orb_publish(ORB_ID(ulog_stream_ack), _ulog_stream_ack_pub, &ack);
  	}
  }
  