bizhang_-obav/src/modules/land_detector/LandDetector.cpp

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/**
 * @file LandDetector.cpp
 * Land detection algorithm
 *
 * @author Johan Jansen <jnsn.johan@gmail.com>
 * @author Morten Lysgaard <morten@lysgaard.no>
 */

#include "LandDetector.h"
#include <unistd.h>                 //usleep
#include <drivers/drv_hrt.h>
#include <px4_config.h>
#include <px4_defines.h>

namespace landdetection
{

LandDetector::LandDetector() :
	_landDetectedPub(0),
	_landDetected( {0, false}),
	       _arming_time(0),
	       _taskShouldExit(false),
	       _taskIsRunning(false),
_work{} {
	// ctor
}

LandDetector::~LandDetector()
{
	work_cancel(HPWORK, &_work);
	_taskShouldExit = true;
}

int LandDetector::start()
{
	/* schedule a cycle to start things */
	work_queue(HPWORK, &_work, (worker_t)&LandDetector::cycle_trampoline, this, 0);

	return 0;
}

void LandDetector::shutdown()
{
	_taskShouldExit = true;
}

void
LandDetector::cycle_trampoline(void *arg)
{
	LandDetector *dev = reinterpret_cast<LandDetector *>(arg);

	dev->cycle();
}

void LandDetector::cycle()
{
	if (!_taskIsRunning) {
		// advertise the first land detected uORB
		_landDetected.timestamp = hrt_absolute_time();
		_landDetected.landed = false;
		_landDetected.freefall = false;
		_landDetectedPub = orb_advertise(ORB_ID(vehicle_land_detected), &_landDetected);

		// initialize land detection algorithm
		initialize();

		// task is now running, keep doing so until shutdown() has been called
		_taskIsRunning = true;
		_taskShouldExit = false;
	}

	LandDetectionResult current_state = update();
	bool landDetected = (current_state == LANDDETECTION_RES_LANDED);
	bool freefallDetected = (current_state == LANDDETECTION_RES_FREEFALL);

	// publish if land detection state has changed
	if ((_landDetected.landed != landDetected) || (_landDetected.freefall != freefallDetected)) {
		_landDetected.timestamp = hrt_absolute_time();
		_landDetected.landed = landDetected;
		_landDetected.freefall = freefallDetected;

		// publish the land detected broadcast
		orb_publish(ORB_ID(vehicle_land_detected), (orb_advert_t)_landDetectedPub, &_landDetected);
		//warnx("in air status changed: %s", (_landDetected.landed) ? "LANDED" : "TAKEOFF");
	}

	if (!_taskShouldExit) {
		work_queue(HPWORK, &_work, (worker_t)&LandDetector::cycle_trampoline, this,
			   USEC2TICK(1000000 / LAND_DETECTOR_UPDATE_RATE));
	}
}

bool LandDetector::orb_update(const struct orb_metadata *meta, int handle, void *buffer)
{
	bool newData = false;

	// check if there is new data to grab
	if (orb_check(handle, &newData) != OK) {
		return false;
	}

	if (!newData) {
		return false;
	}

	if (orb_copy(meta, handle, buffer) != OK) {
		return false;
	}

	return true;
}

}