orb_advert_t changed to void * and checks changed to nullptr

The existing orb_advert_t use thoughout the code sometimes tries
to treat it as a file descriptor and there are checks for < 0
and ::close calls on orb_advert_t types which is an invalid use
of an object pointer, which is what orb_advert_t really is.

Initially I had changed the -1 initializations to 0 but it was
suggested that this should be nullptr. That was a good recommendation
but the definition of orb_advert_t had to change to void * because
you cannot initialize a uintptr_t as nullptr.

Signed-off-by: Mark Charlebois <charlebm@gmail.com>

src/platforms/posix/drivers/accelsim/accelsim.cpp

@@ -369,7 +369,7 @@ ACCELSIM::ACCELSIM(const char* path, enum Rotation rotation) :
 	_mag_range_ga(0.0f),
 	_mag_range_scale(0.0f),
 	_mag_samplerate(0),
-	_accel_topic(0),
+	_accel_topic(nullptr),
 	_accel_orb_class_instance(-1),
 	_accel_class_instance(-1),
 	_accel_read(0),
@@ -481,7 +481,7 @@ ACCELSIM::init()
 	_mag->_mag_topic = orb_advertise_multi(ORB_ID(sensor_mag), &mrp,
 		&_mag->_mag_orb_class_instance, ORB_PRIO_LOW);
 
-	if (_mag->_mag_topic == 0) {
+	if (_mag->_mag_topic == nullptr) {
 		PX4_WARN("ADVERT ERR");
 	}
 
@@ -496,7 +496,7 @@ ACCELSIM::init()
 	_accel_topic = orb_advertise_multi(ORB_ID(sensor_accel), &arp,
 		&_accel_orb_class_instance, ORB_PRIO_DEFAULT);
 
-	if (_accel_topic == 0) {
+	if (_accel_topic == nullptr) {
 		PX4_WARN("ADVERT ERR");
 	}
 
@@ -1077,7 +1077,7 @@ ACCELSIM::measure()
 
 		// The first call to measure() is from init() and _accel_topic is not
 		// yet initialized
-		if (_accel_topic != 0) {
+		if (_accel_topic != nullptr) {
 			orb_publish(ORB_ID(sensor_accel), _accel_topic, &accel_report);
 		}
 	}
@@ -1175,7 +1175,7 @@ ACCELSIM::mag_measure()
 ACCELSIM_mag::ACCELSIM_mag(ACCELSIM *parent) :
 	VDev("ACCELSIM_mag", ACCELSIM_DEVICE_PATH_MAG),
 	_parent(parent),
-	_mag_topic(-1),
+	_mag_topic(nullptr),
 	_mag_orb_class_instance(-1),
 	_mag_class_instance(-1)
 {

src/platforms/posix/drivers/airspeedsim/airspeedsim.cpp

@@ -83,8 +83,8 @@ Airspeed::Airspeed(int bus, int address, unsigned conversion_interval, const cha
 	_measure_ticks(0),
 	_collect_phase(false),
 	_diff_pres_offset(0.0f),
-	_airspeed_pub(0),
-	_subsys_pub(0),
+	_airspeed_pub(nullptr),
+	_subsys_pub(nullptr),
 	_class_instance(-1),
 	_conversion_interval(conversion_interval),
 	_sample_perf(perf_alloc(PC_ELAPSED, "airspeed_read")),
@@ -143,7 +143,7 @@ Airspeed::init()
 		/* measurement will have generated a report, publish */
 		_airspeed_pub = orb_advertise(ORB_ID(differential_pressure), &arp);
 
-		if (_airspeed_pub == 0)
+		if (_airspeed_pub == nullptr)
 			PX4_WARN("uORB started?");
 	}
 
@@ -364,7 +364,7 @@ Airspeed::update_status()
 			SUBSYSTEM_TYPE_DIFFPRESSURE
 		};
 
-		if (_subsys_pub > 0) {
+		if (_subsys_pub != nullptr) {
 			orb_publish(ORB_ID(subsystem_info), _subsys_pub, &info);
 		} else {
 			_subsys_pub = orb_advertise(ORB_ID(subsystem_info), &info);

src/platforms/posix/drivers/barosim/baro.cpp

@@ -213,7 +213,7 @@ BAROSIM::BAROSIM(device::Device *interface, barosim::prom_u &prom_buf, const cha
 	_OFF(0),
 	_SENS(0),
 	_msl_pressure(101325),
-	_baro_topic(0),
+	_baro_topic(nullptr),
 	_orb_class_instance(-1),
 	_class_instance(-1),
 	_sample_perf(perf_alloc(PC_ELAPSED, "barosim_read")),
@@ -315,7 +315,7 @@ BAROSIM::init()
 		_baro_topic = orb_advertise_multi(ORB_ID(sensor_baro), &brp,
 				&_orb_class_instance, (is_external()) ? ORB_PRIO_HIGH : ORB_PRIO_DEFAULT);
 
-		if (_baro_topic == 0) {
+		if (_baro_topic == nullptr) {
 			PX4_ERR("failed to create sensor_baro publication");
 		}
 		//PX4_WARN("sensor_baro publication %ld", _baro_topic);
@@ -722,7 +722,7 @@ BAROSIM::collect()
 
 		/* publish it */
 		if (!(_pub_blocked)) {
-			if (_baro_topic != 0) {
+			if (_baro_topic != nullptr) {
 				/* publish it */
 				orb_publish(ORB_ID(sensor_baro), _baro_topic, &report);
 			}

src/platforms/posix/drivers/gyrosim/gyrosim.cpp

@@ -472,7 +472,7 @@ GYROSIM::GYROSIM(const char *path_accel, const char *path_gyro, enum Rotation ro
 	_accel_scale{},
 	_accel_range_scale(0.0f),
 	_accel_range_m_s2(0.0f),
-	_accel_topic(0),
+	_accel_topic(nullptr),
 	_accel_orb_class_instance(-1),
 	_accel_class_instance(-1),
 	_gyro_reports(nullptr),
@@ -624,7 +624,7 @@ GYROSIM::init()
 	_accel_topic = orb_advertise_multi(ORB_ID(sensor_accel), &arp,
 		&_accel_orb_class_instance, ORB_PRIO_HIGH);
 
-	if (_accel_topic == 0) {
+	if (_accel_topic == nullptr) {
 		PX4_WARN("ADVERT FAIL");
 	}
 
@@ -636,7 +636,7 @@ GYROSIM::init()
 	_gyro->_gyro_topic = orb_advertise_multi(ORB_ID(sensor_gyro), &grp,
 		&_gyro->_gyro_orb_class_instance, ORB_PRIO_HIGH);
 
-	if (_gyro->_gyro_topic == 0) {
+	if (_gyro->_gyro_topic == nullptr) {
 		PX4_WARN("ADVERT FAIL");
 	}
 
@@ -1547,7 +1547,7 @@ GYROSIM::print_registers()
 GYROSIM_gyro::GYROSIM_gyro(GYROSIM *parent, const char *path) :
 	VDev("GYROSIM_gyro", path),
 	_parent(parent),
-	_gyro_topic(0),
+	_gyro_topic(nullptr),
 	_gyro_orb_class_instance(-1),
 	_gyro_class_instance(-1)
 {