Initial stab at supporting multiple publications on the same base name and auto-enumeration of additional publications.

9 files changed, 266 insertions, 83 deletions

diff --git a/src/drivers/drv_orb_dev.h b/src/drivers/drv_orb_dev.h
index 713618545..e0b16fa5c 100644
--- a/src/drivers/drv_orb_dev.h
+++ b/src/drivers/drv_orb_dev.h
@@ -1,6 +1,6 @@
 /****************************************************************************
  *
- *   Copyright (C) 2012 PX4 Development Team. All rights reserved.
+ *   Copyright (c) 2012-2015 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
@@ -35,7 +35,9 @@
 #define _DRV_UORB_H
 
 /**
- * @file uORB published object driver.
+ * @file drv_orb_dev.h
+ * 
+ * uORB published object driver.
  */
 
 #include <sys/types.h>
@@ -84,4 +86,7 @@
 /** Get the global advertiser handle for the topic */
 #define ORBIOCGADVERTISER	_ORBIOC(13)
 
+/** Get the priority for the topic */
+#define ORBIOCGPRIORITY		_ORBIOC(14)
+
 #endif /* _DRV_UORB_H */
diff --git a/src/modules/uORB/Publication.cpp b/src/modules/uORB/Publication.cpp
index 71757e1f4..d33f93060 100644
--- a/src/modules/uORB/Publication.cpp
+++ b/src/modules/uORB/Publication.cpp
@@ -1,6 +1,6 @@
 /****************************************************************************
  *
- *   Copyright (C) 2012 PX4 Development Team. All rights reserved.
+ *   Copyright (c) 2012-2015 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
diff --git a/src/modules/uORB/Publication.hpp b/src/modules/uORB/Publication.hpp
index 8650b3df8..b64559734 100644
--- a/src/modules/uORB/Publication.hpp
+++ b/src/modules/uORB/Publication.hpp
@@ -1,6 +1,6 @@
 /****************************************************************************
  *
- *   Copyright (C) 2012 PX4 Development Team. All rights reserved.
+ *   Copyright (c) 2012-2015 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
diff --git a/src/modules/uORB/Subscription.cpp b/src/modules/uORB/Subscription.cpp
index 44b6debc7..8884e5a3a 100644
--- a/src/modules/uORB/Subscription.cpp
+++ b/src/modules/uORB/Subscription.cpp
@@ -1,6 +1,6 @@
 /****************************************************************************
  *
- *   Copyright (C) 2012 PX4 Development Team. All rights reserved.
+ *   Copyright (c) 2012-2015 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
diff --git a/src/modules/uORB/Subscription.hpp b/src/modules/uORB/Subscription.hpp
index 34e9a83e0..75cf36254 100644
--- a/src/modules/uORB/Subscription.hpp
+++ b/src/modules/uORB/Subscription.hpp
@@ -1,6 +1,6 @@
 /****************************************************************************
  *
- *   Copyright (C) 2012 PX4 Development Team. All rights reserved.
+ *   Copyright (c) 2012-2015 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
diff --git a/src/modules/uORB/module.mk b/src/modules/uORB/module.mk
index 9385ce253..71ad09130 100644
--- a/src/modules/uORB/module.mk
+++ b/src/modules/uORB/module.mk
@@ -1,6 +1,6 @@
 ############################################################################
 #
-#   Copyright (c) 2012, 2013 PX4 Development Team. All rights reserved.
+#   Copyright (c) 2012-2015 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
@@ -37,8 +37,7 @@
 
 MODULE_COMMAND		= uorb
 
-# XXX probably excessive, 2048 should be sufficient
-MODULE_STACKSIZE	= 4096
+MODULE_STACKSIZE	= 2048
 
 SRCS			= uORB.cpp \
 			  objects_common.cpp \
diff --git a/src/modules/uORB/objects_common.cpp b/src/modules/uORB/objects_common.cpp
index 78fdf4de7..20a9bcc43 100644
--- a/src/modules/uORB/objects_common.cpp
+++ b/src/modules/uORB/objects_common.cpp
@@ -1,6 +1,6 @@
 /****************************************************************************
  *
- *   Copyright (C) 2012-2014 PX4 Development Team. All rights reserved.
+ *   Copyright (c) 2012-2015 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
diff --git a/src/modules/uORB/uORB.cpp b/src/modules/uORB/uORB.cpp
index 3373aac83..cfea12f04 100644
--- a/src/modules/uORB/uORB.cpp
+++ b/src/modules/uORB/uORB.cpp
@@ -1,6 +1,6 @@
 /****************************************************************************
  *
- *   Copyright (Cc) 2012-2015 PX4 Development Team. All rights reserved.
+ *   Copyright (c) 2012-2015 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
@@ -51,6 +51,7 @@
 #include <stdio.h>
 #include <math.h>
 #include <unistd.h>
+#include <systemlib/err.h>
 
 #include <nuttx/arch.h>
 #include <nuttx/wqueue.h>
@@ -68,6 +69,7 @@
 namespace
 {
 
+/* internal use only */
 static const unsigned orb_maxpath = 64;
 
 /* oddly, ERROR is not defined for c++ */
@@ -81,17 +83,30 @@ enum Flavor {
 	PARAM
 };
 
+struct orb_advertdata {
+	const struct orb_metadata *meta;
+	int *instance;
+	int priority;
+};
+
 int
-node_mkpath(char *buf, Flavor f, const struct orb_metadata *meta)
+node_mkpath(char *buf, Flavor f, const struct orb_metadata *meta, int *instance = nullptr)
 {
 	unsigned len;
 
-	len = snprintf(buf, orb_maxpath, "/%s/%s",
-		       (f == PUBSUB) ? "obj" : "param",
-		       meta->o_name);
+	unsigned index = 0;
+
+	if (instance != nullptr) {
+		index = *instance;
+	}
+
+	len = snprintf(buf, orb_maxpath, "/%s/%s%d",
+			(f == PUBSUB) ? "obj" : "param",
+			meta->o_name, index);
 
-	if (len >= orb_maxpath)
+	if (len >= orb_maxpath) {
 		return -ENAMETOOLONG;
+	}
 
 	return OK;
 }
@@ -104,7 +119,7 @@ node_mkpath(char *buf, Flavor f, const struct orb_metadata *meta)
 class ORBDevNode : public device::CDev
 {
 public:
-	ORBDevNode(const struct orb_metadata *meta, const char *name, const char *path);
+	ORBDevNode(const struct orb_metadata *meta, const char *name, const char *path, int priority);
 	~ORBDevNode();
 
 	virtual int		open(struct file *filp);
@@ -126,6 +141,7 @@ private:
 		struct hrt_call	update_call;	/**< deferred wakeup call if update_period is nonzero */
 		void		*poll_priv;	/**< saved copy of fds->f_priv while poll is active */
 		bool		update_reported; /**< true if we have reported the update via poll/check */
+		int		priority;	/**< priority of publisher */
 	};
 
 	const struct orb_metadata *_meta;	/**< object metadata information */
@@ -133,6 +149,7 @@ private:
 	hrt_abstime		_last_update;	/**< time the object was last updated */
 	volatile unsigned 	_generation;	/**< object generation count */
 	pid_t			_publisher;	/**< if nonzero, current publisher */
+	const int		_priority;	/**< priority of topic */
 
 	SubscriberData		*filp_to_sd(struct file *filp) {
 		SubscriberData *sd = (SubscriberData *)(filp->f_priv);
@@ -160,13 +177,14 @@ private:
 	bool			appears_updated(SubscriberData *sd);
 };
 
-ORBDevNode::ORBDevNode(const struct orb_metadata *meta, const char *name, const char *path) :
+ORBDevNode::ORBDevNode(const struct orb_metadata *meta, const char *name, const char *path, int priority) :
 	CDev(name, path),
 	_meta(meta),
 	_data(nullptr),
 	_last_update(0),
 	_generation(0),
-	_publisher(0)
+	_publisher(0),
+	_priority(priority)
 {
 	// enable debug() calls
 	_debug_enabled = true;
@@ -176,6 +194,7 @@ ORBDevNode::~ORBDevNode()
 {
 	if (_data != nullptr)
 		delete[] _data;
+
 }
 
 int
@@ -225,6 +244,9 @@ ORBDevNode::open(struct file *filp)
 		/* default to no pending update */
 		sd->generation = _generation;
 
+		/* set priority */
+		sd->priority = _priority;
+
 		filp->f_priv = (void *)sd;
 
 		ret = CDev::open(filp);
@@ -283,6 +305,9 @@ ORBDevNode::read(struct file *filp, char *buffer, size_t buflen)
 	/* track the last generation that the file has seen */
 	sd->generation = _generation;
 
+	/* set priority */
+	sd->priority = _priority;
+
 	/*
 	 * Clear the flag that indicates that an update has been reported, as
 	 * we have just collected it.
@@ -364,6 +389,10 @@ ORBDevNode::ioctl(struct file *filp, int cmd, unsigned long arg)
 		*(uintptr_t *)arg = (uintptr_t)this;
 		return OK;
 
+	case ORBIOCGPRIORITY:
+		*(int *)arg = sd->priority;
+		return OK;
+
 	default:
 		/* give it to the superclass */
 		return CDev::ioctl(filp, cmd, arg);
@@ -556,40 +585,73 @@ ORBDevMaster::ioctl(struct file *filp, int cmd, unsigned long arg)
 
 	switch (cmd) {
 	case ORBIOCADVERTISE: {
-			const struct orb_metadata *meta = (const struct orb_metadata *)arg;
+			const struct orb_advertdata *adv = (const struct orb_advertdata *)arg;
+			const struct orb_metadata *meta = adv->meta;
 			const char *objname;
+			const char *devpath;
 			char nodepath[orb_maxpath];
 			ORBDevNode *node;
 
 			/* construct a path to the node - this also checks the node name */
-			ret = node_mkpath(nodepath, _flavor, meta);
+			ret = node_mkpath(nodepath, _flavor, meta, adv->instance);
 
-			if (ret != OK)
+			if (ret != OK) {
 				return ret;
+			}
 
 			/* driver wants a permanent copy of the node name, so make one here */
 			objname = strdup(meta->o_name);
 
-			if (objname == nullptr)
+			if (objname == nullptr) {
 				return -ENOMEM;
+			}
 
-			/* construct the new node */
-			node = new ORBDevNode(meta, objname, nodepath);
+			/* ensure that only one advertiser runs through this critical section */
+			lock();
 
-			/* initialise the node - this may fail if e.g. a node with this name already exists */
-			if (node != nullptr)
+			ret = ERROR;
+
+			/* try for topic groups */
+			const unsigned max_group_tries = (adv->instance != nullptr) ? ORB_MULTI_MAX_INSTANCES : 1;
+			unsigned group_tries = 0;
+			do {
+				/* if path is modifyable change try index */
+				if (adv->instance != nullptr) {
+					/* replace the number at the end of the string */
+					nodepath[strlen(nodepath) - 1] = '0' + group_tries;
+					*(adv->instance) = group_tries;
+				}
+
+				/* driver wants a permanent copy of the path, so make one here */
+				devpath = strdup(nodepath);
+
+				/* construct the new node */
+				node = new ORBDevNode(meta, objname, devpath, adv->priority);
+
+				/* if we didn't get a device, that's bad */
+				if (node == nullptr) {
+					unlock();
+					return -ENOMEM;
+				}
+
+				/* initialise the node - this may fail if e.g. a node with this name already exists */
 				ret = node->init();
+				
+				/* if init failed, discard the node and its name */
+				if (ret != OK) {
+					delete node;
+					free((void *)objname);
+				}
 
-			/* if we didn't get a device, that's bad */
-			if (node == nullptr)
-				return -ENOMEM;
+			} while (ret != OK && (group_tries++ < max_group_tries));
 
-			/* if init failed, discard the node and its name */
-			if (ret != OK) {
-				delete node;
-				free((void *)objname);
+			if (group_tries >= max_group_tries) {
+				ret = -ENOMEM;
 			}
 
+			/* the file handle for the driver has been created, unlock */
+			unlock();
+
 			return ret;
 		}
 
@@ -614,6 +676,7 @@ struct orb_test {
 };
 
 ORB_DEFINE(orb_test, struct orb_test);
+ORB_DEFINE(orb_multitest, struct orb_test);
 
 int
 test_fail(const char *fmt, ...)
@@ -643,8 +706,6 @@ test_note(const char *fmt, ...)
 	return OK;
 }
 
-ORB_DECLARE(sensor_combined);
-
 int
 test()
 {
@@ -700,48 +761,65 @@ test()
 	orb_unsubscribe(sfd);
 	close(pfd);
 
-#if 0
-	/* this is a hacky test that exploits the sensors app to test rate-limiting */
+	/* this routine tests the multi-topic support */
+	test_note("try multi-topic support");
 
-	sfd = orb_subscribe(ORB_ID(sensor_combined));
+	int instance0;
+	int pfd0 = orb_advertise_multi(ORB_ID(orb_multitest), &t, &instance0, ORB_PRIO_MAX);
 
-	hrt_abstime start, end;
-	unsigned count;
+		test_note("advertised");
+	usleep(300000);
 
-	start = hrt_absolute_time();
-	count = 0;
+	int instance1;
+	int pfd1 = orb_advertise_multi(ORB_ID(orb_multitest), &t, &instance1, ORB_PRIO_MIN);
 
-	do {
-		orb_check(sfd, &updated);
+	if (instance0 != 0)
+		return test_fail("mult. id0: %d", instance0);
 
-		if (updated) {
-			orb_copy(ORB_ID(sensor_combined), sfd, nullptr);
-			count++;
-		}
-	} while (count < 100);
+	if (instance1 != 1)
+		return test_fail("mult. id1: %d", instance1);
 
-	end = hrt_absolute_time();
-	test_note("full-speed, 100 updates in %llu", end - start);
+	t.val = 103;
+	if (OK != orb_publish(ORB_ID(orb_multitest), pfd0, &t))
+		return test_fail("mult. pub0 fail");
 
-	orb_set_interval(sfd, 10);
+		test_note("published");
+	usleep(300000);
 
-	start = hrt_absolute_time();
-	count = 0;
+	t.val = 203;
+	if (OK != orb_publish(ORB_ID(orb_multitest), pfd1, &t))
+		return test_fail("mult. pub1 fail");
 
-	do {
-		orb_check(sfd, &updated);
+	/* subscribe to both topics and ensure valid data is received */
+	int sfd0 = orb_subscribe_multi(ORB_ID(orb_multitest), 0);
 
-		if (updated) {
-			orb_copy(ORB_ID(sensor_combined), sfd, nullptr);
-			count++;
-		}
-	} while (count < 100);
+	if (OK != orb_copy(ORB_ID(orb_multitest), sfd0, &t))
+		return test_fail("sub #0 copy failed: %d", errno);
 
-	end = hrt_absolute_time();
-	test_note("100Hz, 100 updates in %llu", end - start);
+	if (t.val != 103)
+		return test_fail("sub #0 val. mismatch: %d", t.val);
 
-	orb_unsubscribe(sfd);
-#endif
+	int sfd1 = orb_subscribe_multi(ORB_ID(orb_multitest), 1);
+
+	if (OK != orb_copy(ORB_ID(orb_multitest), sfd1, &t))
+		return test_fail("sub #1 copy failed: %d", errno);
+
+	if (t.val != 203)
+		return test_fail("sub #1 val. mismatch: %d", t.val);
+
+	/* test priorities */
+	int prio;
+	if (OK != orb_priority(sfd0, &prio))
+		return test_fail("prio #0");
+	
+	if (prio != ORB_PRIO_MAX)
+		return test_fail("prio: %d", prio);
+
+	if (OK != orb_priority(sfd1, &prio))
+		return test_fail("prio #1");
+
+	if (prio != ORB_PRIO_MIN)
+		return test_fail("prio: %d", prio);
 
 	return test_note("PASS");
 }
@@ -771,7 +849,7 @@ uorb_main(int argc, char *argv[])
 	if (!strcmp(argv[1], "start")) {
 
 		if (g_dev != nullptr) {
-			fprintf(stderr, "[uorb] already loaded\n");
+			warnx("already loaded");
 			/* user wanted to start uorb, its already running, no error */
 			return 0;
 		}
@@ -780,18 +858,17 @@ uorb_main(int argc, char *argv[])
 		g_dev = new ORBDevMaster(PUBSUB);
 
 		if (g_dev == nullptr) {
-			fprintf(stderr, "[uorb] driver alloc failed\n");
+			warnx("driver alloc failed");
 			return -ENOMEM;
 		}
 
 		if (OK != g_dev->init()) {
-			fprintf(stderr, "[uorb] driver init failed\n");
+			warnx("driver init failed");
 			delete g_dev;
 			g_dev = nullptr;
 			return -EIO;
 		}
 
-		printf("[uorb] ready\n");
 		return OK;
 	}
 
@@ -807,8 +884,7 @@ uorb_main(int argc, char *argv[])
 	if (!strcmp(argv[1], "status"))
 		return info();
 
-	fprintf(stderr, "unrecognised command, try 'start', 'test' or 'status'\n");
-	return -EINVAL;
+	errx(-EINVAL, "unrecognized command, try 'start', 'test' or 'status'");
 }
 
 /*
@@ -825,11 +901,14 @@ namespace
  *       we tried to advertise.
  */
 int
-node_advertise(const struct orb_metadata *meta)
+node_advertise(const struct orb_metadata *meta, int *instance = nullptr, int priority = ORB_PRIO_DEFAULT)
 {
 	int fd = -1;
 	int ret = ERROR;
 
+	/* fill advertiser data */
+	const struct orb_advertdata adv = { meta, instance, priority };
+
 	/* open the control device */
 	fd = open(TOPIC_MASTER_DEVICE_PATH, 0);
 
@@ -837,11 +916,12 @@ node_advertise(const struct orb_metadata *meta)
 		goto out;
 
 	/* advertise the object */
-	ret = ioctl(fd, ORBIOCADVERTISE, (unsigned long)(uintptr_t)meta);
+	ret = ioctl(fd, ORBIOCADVERTISE, (unsigned long)(uintptr_t)&adv);
 
 	/* it's OK if it already exists */
-	if ((OK != ret) && (EEXIST == errno))
+	if ((OK != ret) && (EEXIST == errno)) {
 		ret = OK;
+	}
 
 out:
 
@@ -858,7 +938,7 @@ out:
  * advertisers.
  */
 int
-node_open(Flavor f, const struct orb_metadata *meta, const void *data, bool advertiser)
+node_open(Flavor f, const struct orb_metadata *meta, const void *data, bool advertiser, int *instance = nullptr, int priority = ORB_PRIO_DEFAULT)
 {
 	char path[orb_maxpath];
 	int fd, ret;
@@ -883,7 +963,7 @@ node_open(Flavor f, const struct orb_metadata *meta, const void *data, bool adve
 	/*
 	 * Generate the path to the node and try to open it.
 	 */
-	ret = node_mkpath(path, f, meta);
+	ret = node_mkpath(path, f, meta, instance);
 
 	if (ret != OK) {
 		errno = -ret;
@@ -893,15 +973,34 @@ node_open(Flavor f, const struct orb_metadata *meta, const void *data, bool adve
 	/* open the path as either the advertiser or the subscriber */
 	fd = open(path, (advertiser) ? O_WRONLY : O_RDONLY);
 
+	/* if we want to advertise and the node existed, we have to re-try again */
+	if ((fd >= 0) && (instance != nullptr) && (advertiser)) {
+		/* close the fd, we want a new one */
+		close(fd);
+		/* the node_advertise call will automatically go for the next free entry */
+		fd = -1;
+	}
+
 	/* we may need to advertise the node... */
 	if (fd < 0) {
 
 		/* try to create the node */
-		ret = node_advertise(meta);
+		ret = node_advertise(meta, instance, priority);
+
+		if (ret == OK) {
+			/* update the path, as it might have been updated during the node_advertise call */
+			ret = node_mkpath(path, f, meta, instance);
+
+			if (ret != OK) {
+				errno = -ret;
+				return ERROR;
+			}
+		}
 
 		/* on success, try the open again */
-		if (ret == OK)
+		if (ret == OK) {
 			fd = open(path, (advertiser) ? O_WRONLY : O_RDONLY);
+		}
 	}
 
 	if (fd < 0) {
@@ -918,11 +1017,17 @@ node_open(Flavor f, const struct orb_metadata *meta, const void *data, bool adve
 orb_advert_t
 orb_advertise(const struct orb_metadata *meta, const void *data)
 {
+	return orb_advertise_multi(meta, data, nullptr, ORB_PRIO_DEFAULT);
+}
+
+orb_advert_t
+orb_advertise_multi(const struct orb_metadata *meta, const void *data, int *instance, int priority)
+{
 	int result, fd;
 	orb_advert_t advertiser;
 
 	/* open the node as an advertiser */
-	fd = node_open(PUBSUB, meta, data, true);
+	fd = node_open(PUBSUB, meta, data, true, instance, priority);
 	if (fd == ERROR)
 		return ERROR;
 
@@ -933,7 +1038,7 @@ orb_advertise(const struct orb_metadata *meta, const void *data)
 		return ERROR;
 
 	/* the advertiser must perform an initial publish to initialise the object */
-	result= orb_publish(meta, advertiser, data);
+	result = orb_publish(meta, advertiser, data);
 	if (result == ERROR)
 		return ERROR;
 
@@ -947,6 +1052,13 @@ orb_subscribe(const struct orb_metadata *meta)
 }
 
 int
+orb_subscribe_multi(const struct orb_metadata *meta, unsigned instance)
+{
+	int inst = instance;
+	return node_open(PUBSUB, meta, nullptr, false, &inst);
+}
+
+int
 orb_unsubscribe(int handle)
 {
 	return close(handle);
@@ -989,6 +1101,12 @@ orb_stat(int handle, uint64_t *time)
 }
 
 int
+orb_priority(int handle, int *priority)
+{
+	return ioctl(handle, ORBIOCGPRIORITY, (unsigned long)(uintptr_t)priority);
+}
+
+int
 orb_set_interval(int handle, unsigned interval)
 {
 	return ioctl(handle, ORBIOCSETINTERVAL, interval * 1000);
diff --git a/src/modules/uORB/uORB.h b/src/modules/uORB/uORB.h
index beb23f61d..a0ad75273 100644
--- a/src/modules/uORB/uORB.h
+++ b/src/modules/uORB/uORB.h
@@ -1,6 +1,6 @@
 /****************************************************************************
  *
- *   Copyright (C) 2012 PX4 Development Team. All rights reserved.
+ *   Copyright (c) 2012-2015 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
@@ -57,6 +57,25 @@ struct orb_metadata {
 typedef const struct orb_metadata *orb_id_t;
 
 /**
+ * Maximum number of multi topic instances
+ */
+#define ORB_MULTI_MAX_INSTANCES	4
+
+/**
+ * Topic priority.
+ * Relevant for multi-topics / topic groups
+ */
+enum ORB_PRIO {
+	ORB_PRIO_MIN = 0,
+	ORB_PRIO_VERY_LOW = 25,
+	ORB_PRIO_LOW = 50,
+	ORB_PRIO_DEFAULT = 75,
+	ORB_PRIO_HIGH = 100,
+	ORB_PRIO_VERY_HIGH = 125,
+	ORB_PRIO_MAX = 255
+};
+
+/**
  * Generates a pointer to the uORB metadata structure for
  * a given topic.
  *
@@ -128,7 +147,7 @@ typedef const struct orb_metadata *orb_id_t;
 #define ORB_DEFINE(_name, _struct)			\
 	const struct orb_metadata __orb_##_name = {	\
 		#_name,					\
-		sizeof(_struct)				\
+		sizeof(_struct),			\
 	}; struct hack
 
 __BEGIN_DECLS
@@ -168,6 +187,34 @@ typedef intptr_t	orb_advert_t;
 extern orb_advert_t orb_advertise(const struct orb_metadata *meta, const void *data) __EXPORT;
 
 /**
+ * Advertise as the publisher of a topic.
+ *
+ * This performs the initial advertisement of a topic; it creates the topic
+ * node in /obj if required and publishes the initial data.
+ *
+ * Any number of advertisers may publish to a topic; publications are atomic
+ * but co-ordination between publishers is not provided by the ORB. 
+ *
+ * @param meta		The uORB metadata (usually from the ORB_ID() macro)
+ *			for the topic.
+ * @param data		A pointer to the initial data to be published.
+ *			For topics updated by interrupt handlers, the advertisement
+ *			must be performed from non-interrupt context.
+ * @param instance	Pointer to an integer which will yield the instance ID (0-based)
+ *			of the publication.
+ * @param priority	The priority of the instance. If a subscriber subscribes multiple
+ *			instances, the priority allows the subscriber to prioritize the best
+ *			data source as long as its available.
+ * @return		ERROR on error, otherwise returns a handle
+ *			that can be used to publish to the topic.
+ *			If the topic in question is not known (due to an
+ *			ORB_DEFINE with no corresponding ORB_DECLARE)
+ *			this function will return -1 and set errno to ENOENT.
+ */
+extern orb_advert_t orb_advertise_multi(const struct orb_metadata *meta, const void *data, int *instance, int priority) __EXPORT;
+
+
+/**
  * Publish new data to a topic.
  *
  * The data is atomically published to the topic and any waiting subscribers
@@ -210,6 +257,8 @@ extern int	orb_publish(const struct orb_metadata *meta, orb_advert_t handle, con
  */
 extern int	orb_subscribe(const struct orb_metadata *meta) __EXPORT;
 
+extern int	orb_subscribe_multi(const struct orb_metadata *meta, unsigned instance) __EXPORT;
+
 /**
  * Unsubscribe from a topic.
  *
@@ -267,6 +316,18 @@ extern int	orb_check(int handle, bool *updated) __EXPORT;
 extern int	orb_stat(int handle, uint64_t *time) __EXPORT;
 
 /**
+ * Return the priority of the topic
+ *
+ * @param handle	A handle returned from orb_subscribe.
+ * @param priority	Returns the priority of this topic. This is only relevant for
+ *			topics which are published by multiple publishers (e.g. mag0, mag1, etc.)
+ *			and allows a subscriber to automatically pick the topic with the highest
+ *			priority, independent of the startup order of the associated publishers.
+ * @return		OK on success, ERROR otherwise with errno set accordingly.
+ */
+extern int	orb_priority(int handle, int *priority) __EXPORT;
+
+/**
  * Set the minimum interval between which updates are seen for a subscription.
  *
  * If this interval is set, the subscriber will not see more than one update