move posix, nuttx, qurt components into platforms

2026-05-21 01:12:11 +00:00 · 2018-01-15 15:34:18 -05:00
parent a644ed90dd
commit 2ff81393bc
115 changed files with 251 additions and 306 deletions
--- a/platforms/posix/CMakeLists.txt
+++ b/platforms/posix/CMakeLists.txt
@@ -1,5 +1,7 @@
 include (common/px4_upload)

+add_subdirectory(src)
+
 include_directories(${CMAKE_CURRENT_BINARY_DIR})

 get_property(module_libraries GLOBAL PROPERTY PX4_LIBRARIES)
@@ -10,7 +12,7 @@ px4_posix_generate_builtin_commands(

 # Define build target
 set(APP_NAME px4)
-set(MAIN_SRC ${PX4_SOURCE_DIR}/src/platforms/posix/main.cpp)
+set(MAIN_SRC src/main.cpp)
 set(UPLOAD_NAME upload)

 if ("${BOARD}" STREQUAL "eagle" OR ("${BOARD}" STREQUAL "excelsior"))
--- a/platforms/posix/cmake/px4_impl_os.cmake
+++ b/platforms/posix/cmake/px4_impl_os.cmake
@@ -165,9 +165,7 @@ function(px4_os_add_flags)
 		DEFINITIONS ${DEFINITIONS})

        set(added_include_dirs
-		src/modules/systemlib
-		src/platforms/posix/include
-		mavlink/include/mavlink
+		platforms/posix/include
 		)

 	# This block sets added_definitions and added_cxx_flags.
--- a/platforms/posix/cmake/sitl_target.cmake
+++ b/platforms/posix/cmake/sitl_target.cmake
@@ -32,7 +32,7 @@ endfunction()
 # sitl run targets
 #

-set(SITL_RUNNER_MAIN_CPP ${PX4_SOURCE_DIR}/src/platforms/posix/main.cpp)
+set(SITL_RUNNER_MAIN_CPP src/main.cpp)
 px4_add_sitl_app(APP_NAME px4
 		UPLOAD_NAME upload
 		MAIN_SRC ${SITL_RUNNER_MAIN_CPP}
@@ -111,7 +111,7 @@ foreach(viewer ${viewers})
 				set(SITL_RUNNER_MODEL_FILE ${PX4_SOURCE_DIR}/${config_sitl_rcS_dir}/${model})
 				set(SITL_RUNNER_WORKING_DIRECTORY ${SITL_WORKING_DIR})

-				configure_file(${PX4_SOURCE_DIR}/src/platforms/posix/sitl_runner_main.cpp.in sitl_runner_main_${model}.cpp @ONLY)
+				configure_file(src/sitl_runner_main.cpp.in sitl_runner_main_${model}.cpp @ONLY)

 				px4_add_sitl_app(APP_NAME px4_${model}
 						UPLOAD_NAME upload_${model}
--- a/platforms/posix/include/arch/board/board.h
+++ b/platforms/posix/include/arch/board/board.h
--- a/platforms/posix/include/crc32.h
+++ b/platforms/posix/include/crc32.h
@@ -0,0 +1,83 @@
+/****************************************************************************
+ * include/crc.h
+ *
+ *   Copyright (C) 2010 Gregory Nutt. All rights reserved.
+ *   Author: Gregory Nutt <gnutt@nuttx.org>
+ *
+ * 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 NuttX 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.
+ *
+ ****************************************************************************/
+
+#ifndef __INCLUDE_CRC32_H
+#define __INCLUDE_CRC32_H
+
+/****************************************************************************
+ * Included Files
+ ****************************************************************************/
+
+#include <sys/types.h>
+#include <stdint.h>
+
+/****************************************************************************
+ * Public Function Prototypes
+ ****************************************************************************/
+
+#ifdef __cplusplus
+#define EXTERN extern "C"
+extern "C" {
+#else
+#define EXTERN extern
+#endif
+
+/****************************************************************************
+ * Name: crc32part
+ *
+ * Description:
+ *   Continue CRC calculation on a part of the buffer.
+ *
+ ****************************************************************************/
+
+EXTERN uint32_t crc32part(const uint8_t *src, size_t len,
+			  uint32_t crc32val);
+
+/****************************************************************************
+ * Name: crc32
+ *
+ * Description:
+ *   Return a 32-bit CRC of the contents of the 'src' buffer, length 'len'
+ *
+ ****************************************************************************/
+
+EXTERN uint32_t crc32(const uint8_t *src, size_t len);
+
+#undef EXTERN
+#ifdef __cplusplus
+}
+#endif
+
+#endif /* __INCLUDE_CRC32_H */
--- a/platforms/posix/include/hrt_work.h
+++ b/platforms/posix/include/hrt_work.h
@@ -0,0 +1,63 @@
+/****************************************************************************
+ *
+ * Copyright (C) 2015 Mark Charlebois. 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.
+ *
+ ****************************************************************************/
+
+#include <px4_log.h>
+#include <px4_posix.h>
+#include <semaphore.h>
+#include <px4_workqueue.h>
+
+#pragma once
+
+__BEGIN_DECLS
+
+extern px4_sem_t _hrt_work_lock;
+extern struct wqueue_s g_hrt_work;
+
+void hrt_work_queue_init(void);
+int hrt_work_queue(struct work_s *work, worker_t worker, void *arg, uint32_t usdelay);
+void hrt_work_cancel(struct work_s *work);
+
+static inline void hrt_work_lock(void);
+static inline void hrt_work_lock()
+{
+	px4_sem_wait(&_hrt_work_lock);
+}
+
+static inline void hrt_work_unlock(void);
+static inline void hrt_work_unlock()
+{
+	px4_sem_post(&_hrt_work_lock);
+}
+
+__END_DECLS
+
--- a/platforms/posix/include/px4_platform_types.h
+++ b/platforms/posix/include/px4_platform_types.h
@@ -0,0 +1,3 @@
+#ifdef __PX4_QURT
+#include <dspal_types.h>
+#endif
--- a/platforms/posix/include/queue.h
+++ b/platforms/posix/include/queue.h
@@ -0,0 +1,134 @@
+/************************************************************************
+ * include/queue.h
+ *
+ *   Copyright (C) 2007-2009 Gregory Nutt. All rights reserved.
+ *   Author: Gregory Nutt <gnutt@nuttx.org>
+ *
+ * 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 NuttX 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.
+ *
+ ************************************************************************/
+
+#ifndef __INCLUDE_QUEUE_H
+#define __INCLUDE_QUEUE_H
+
+/************************************************************************
+ * Included Files
+ ************************************************************************/
+
+#include <sys/types.h>
+
+#ifdef __cplusplus
+#include <cstddef>	// NULL
+#else
+#include <stddef.h>	// NULL
+#endif
+
+/************************************************************************
+ * Pre-processor Definitions
+ ************************************************************************/
+
+#define sq_init(q) do { (q)->head = NULL; (q)->tail = NULL; } while (0)
+#define dq_init(q) do { (q)->head = NULL; (q)->tail = NULL; } while (0)
+
+#define sq_next(p) ((p)->flink)
+#define dq_next(p) ((p)->flink)
+#define dq_prev(p) ((p)->blink)
+
+#define sq_empty(q) ((q)->head == NULL)
+#define dq_empty(q) ((q)->head == NULL)
+
+#define sq_peek(q)  ((q)->head)
+#define dq_peek(q)  ((q)->head)
+
+// Required for Linux
+#define FAR
+
+/************************************************************************
+ * Global Type Declarations
+ ************************************************************************/
+
+struct sq_entry_s {
+	FAR struct sq_entry_s *flink;
+};
+typedef struct sq_entry_s sq_entry_t;
+
+struct dq_entry_s {
+	FAR struct dq_entry_s *flink;
+	FAR struct dq_entry_s *blink;
+};
+typedef struct dq_entry_s dq_entry_t;
+
+struct sq_queue_s {
+	FAR sq_entry_t *head;
+	FAR sq_entry_t *tail;
+};
+typedef struct sq_queue_s  sq_queue_t;
+
+struct dq_queue_s {
+	FAR dq_entry_t *head;
+	FAR dq_entry_t *tail;
+};
+typedef struct dq_queue_s dq_queue_t;
+
+/************************************************************************
+ * Global Function Prototypes
+ ************************************************************************/
+
+#ifdef __cplusplus
+#define EXTERN extern "C"
+extern "C" {
+#else
+#define EXTERN extern
+#endif
+
+EXTERN void  sq_addfirst(FAR sq_entry_t *node, sq_queue_t *queue);
+EXTERN void  dq_addfirst(FAR dq_entry_t *node, dq_queue_t *queue);
+EXTERN void  sq_addlast(FAR sq_entry_t *node, sq_queue_t *queue);
+EXTERN void  dq_addlast(FAR dq_entry_t *node, dq_queue_t *queue);
+EXTERN void  sq_addafter(FAR sq_entry_t *prev, FAR sq_entry_t *node,
+			 sq_queue_t *queue);
+EXTERN void  dq_addafter(FAR dq_entry_t *prev, FAR dq_entry_t *node,
+			 dq_queue_t *queue);
+EXTERN void  dq_addbefore(FAR dq_entry_t *next, FAR dq_entry_t *node,
+			  dq_queue_t *queue);
+
+EXTERN FAR sq_entry_t *sq_remafter(FAR sq_entry_t *node, sq_queue_t *queue);
+EXTERN void            sq_rem(FAR sq_entry_t *node, sq_queue_t *queue);
+EXTERN void            dq_rem(FAR dq_entry_t *node, dq_queue_t *queue);
+EXTERN FAR sq_entry_t *sq_remlast(sq_queue_t *queue);
+EXTERN FAR dq_entry_t *dq_remlast(dq_queue_t *queue);
+EXTERN FAR sq_entry_t *sq_remfirst(sq_queue_t *queue);
+EXTERN FAR dq_entry_t *dq_remfirst(dq_queue_t *queue);
+
+#undef EXTERN
+#ifdef __cplusplus
+}
+#endif
+
+#endif /* __INCLUDE_QUEUE_H_ */
+
--- a/platforms/posix/include/system_config.h
+++ b/platforms/posix/include/system_config.h
@@ -0,0 +1,74 @@
+/****************************************************************************
+ *
+ *   Copyright (c) 2017 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 system_config.h
+ *
+ * Definitions used by all SITL and Linux targets
+ */
+
+#pragma once
+
+#define ADC_BATTERY_VOLTAGE_CHANNEL     10
+#define ADC_BATTERY_CURRENT_CHANNEL     ((uint8_t)(-1))
+#define ADC_AIRSPEED_VOLTAGE_CHANNEL    11
+#define ADCSIM0_DEVICE_PATH	"/dev/adc0"
+
+#define SIM_FORMATED_UUID "000000010000000200000003"
+#define PX4_CPU_UUID_BYTE_LENGTH 12
+#define PX4_CPU_UUID_WORD32_LENGTH 3
+#define PX4_CPU_MFGUID_BYTE_LENGTH              PX4_CPU_UUID_BYTE_LENGTH
+#define PX4_CPU_UUID_WORD32_UNIQUE_H            2 /* Most significant digits change the least */
+#define PX4_CPU_UUID_WORD32_UNIQUE_M            1 /* Middle significant digits */
+#define PX4_CPU_UUID_WORD32_UNIQUE_L            0 /* Least significant digits change the most */
+#define PX4_CPU_UUID_WORD32_FORMAT_SIZE         (PX4_CPU_UUID_WORD32_LENGTH-1+(2*PX4_CPU_UUID_BYTE_LENGTH)+1)
+#define PX4_CPU_MFGUID_FORMAT_SIZE              ((2*PX4_CPU_MFGUID_BYTE_LENGTH)+1)
+
+#define BOARD_OVERRIDE_CPU_VERSION (-1)
+#define board_mcu_version(rev, revstr, errata) BOARD_OVERRIDE_CPU_VERSION
+
+#define board_get_uuid32(id) do {for(int _idi=0; _idi < PX4_CPU_UUID_WORD32_LENGTH; _idi++) {id[_idi] = _idi;}} while(0)
+#define board_get_uuid32_formated(format_buffer, size, format, seperator) do { strcpy(format_buffer, SIM_FORMATED_UUID); } while(0)
+
+#define BOARD_HAS_NO_UUID
+
+#define CONFIG_NFILE_STREAMS 1
+#define CONFIG_SCHED_WORKQUEUE 1
+#define CONFIG_SCHED_HPWORK 1
+#define CONFIG_SCHED_LPWORK 1
+
+/** time in ms between checks for work in work queues **/
+#define CONFIG_SCHED_WORKPERIOD 50000
+
+#define CONFIG_SCHED_INSTRUMENTATION 1
+#define CONFIG_MAX_TASKS 32
--- a/platforms/posix/src/CMakeLists.txt
+++ b/platforms/posix/src/CMakeLists.txt
@@ -0,0 +1,34 @@
+############################################################################
+#
+#   Copyright (c) 2017 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.
+#
+############################################################################
+
+add_subdirectory(px4_layer)
--- a/platforms/posix/src/main.cpp
+++ b/platforms/posix/src/main.cpp
@@ -0,0 +1,670 @@
+/****************************************************************************
+ *
+ *   Copyright (C) 2015 Mark Charlebois. 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 main.cpp
+ * Basic shell to execute builtin "apps"
+ *
+ * @author Mark Charlebois <charlebm@gmail.com>
+ * @author Roman Bapst <bapstroman@gmail.com>
+ */
+
+#include <iostream>
+#include <fstream>
+#include <string>
+#include <sstream>
+#include <vector>
+#include <signal.h>
+#include <unistd.h>
+#include <stdio.h>
+#include "apps.h"
+#include "px4_middleware.h"
+#include "px4_posix.h"
+#include "px4_log.h"
+#include "DriverFramework.hpp"
+#include <termios.h>
+#include <sys/stat.h>
+
+namespace px4
+{
+void init_once();
+}
+
+using namespace std;
+
+typedef int (*px4_main_t)(int argc, char *argv[]);
+
+#define CMD_BUFF_SIZE	100
+
+#ifdef PATH_MAX
+const unsigned path_max_len = PATH_MAX;
+#else
+const unsigned path_max_len = 1024;
+#endif
+
+static volatile bool _ExitFlag = false;
+
+static struct termios orig_term;
+
+extern "C" {
+	void _SigIntHandler(int sig_num);
+	void _SigIntHandler(int sig_num)
+	{
+		cout.flush();
+		cout << endl << "Exiting..." << endl;
+		cout.flush();
+		_ExitFlag = true;
+	}
+	void _SigFpeHandler(int sig_num);
+	void _SigFpeHandler(int sig_num)
+	{
+		cout.flush();
+		cout << endl << "floating point exception" << endl;
+		PX4_BACKTRACE();
+		cout.flush();
+	}
+}
+
+static inline bool fileExists(const string &name)
+{
+	struct stat buffer;
+	return (stat(name.c_str(), &buffer) == 0);
+}
+
+static inline bool dirExists(const string &path)
+{
+	struct stat info;
+
+	if (stat(path.c_str(), &info) != 0) {
+		return false;
+
+	} else if (info.st_mode & S_IFDIR) {
+		return true;
+
+	} else {
+		return false;
+	}
+}
+
+static inline void touch(const string &name)
+{
+	fstream fs;
+	fs.open(name, ios::out);
+	fs.close();
+}
+
+static int mkpath(const char *path, mode_t mode);
+
+static int do_mkdir(const char *path, mode_t mode)
+{
+	struct stat             st;
+	int             status = 0;
+
+	if (stat(path, &st) != 0) {
+		/* Directory does not exist. EEXIST for race condition */
+		if (mkdir(path, mode) != 0 && errno != EEXIST) {
+			status = -1;
+		}
+
+	} else if (!S_ISDIR(st.st_mode)) {
+		errno = ENOTDIR;
+		status = -1;
+	}
+
+	return (status);
+}
+
+/**
+** mkpath - ensure all directories in path exist
+** Algorithm takes the pessimistic view and works top-down to ensure
+** each directory in path exists, rather than optimistically creating
+** the last element and working backwards.
+*/
+static int mkpath(const char *path, mode_t mode)
+{
+	char           *pp;
+	char           *sp;
+	int             status;
+	char           *copypath = strdup(path);
+
+	status = 0;
+	pp = copypath;
+
+	while (status == 0 && (sp = strchr(pp, '/')) != nullptr) {
+		if (sp != pp) {
+			/* Neither root nor double slash in path */
+			*sp = '\0';
+			status = do_mkdir(copypath, mode);
+			*sp = '/';
+		}
+
+		pp = sp + 1;
+	}
+
+	if (status == 0) {
+		status = do_mkdir(path, mode);
+	}
+
+	free(copypath);
+	return (status);
+}
+
+static string pwd()
+{
+	char temp[path_max_len];
+	return (getcwd(temp, path_max_len) ? string(temp) : string(""));
+}
+
+static void print_prompt()
+{
+	cout.flush();
+	cout << "pxh> ";
+	cout.flush();
+}
+
+static void run_cmd(const vector<string> &appargs, bool exit_on_fail, bool silently_fail = false)
+{
+	static apps_map_type apps;
+	static bool initialized = false;
+
+	if (!initialized) {
+		init_app_map(apps);
+		initialized = true;
+	}
+
+	// command is appargs[0]
+	string command = appargs[0];
+
+	if (apps.find(command) != apps.end()) {
+		const char *arg[appargs.size() + 2];
+
+		unsigned int i = 0;
+
+		while (i < appargs.size() && appargs[i] != "") {
+			arg[i] = (char *)appargs[i].c_str();
+			++i;
+		}
+
+		arg[i] = (char *)nullptr;
+
+		int retval = apps[command](i, (char **)arg);
+
+		if (retval) {
+			cout << "Command '" << command << "' failed, returned " << retval << endl;
+
+			if (exit_on_fail && retval) {
+				exit(retval);
+			}
+		}
+
+	} else if (command == "help") {
+		list_builtins(apps);
+
+	} else if (command.length() == 0 || command[0] == '#') {
+		// Do nothing
+
+	} else if (!silently_fail) {
+		cout << "Invalid command: " << command << "\ntype 'help' for a list of commands" << endl;
+
+	}
+}
+
+static void usage()
+{
+
+	cout << "./px4 [-d] [data_directory] startup_config [-h]" << endl;
+	cout << "   -d            - Optional flag to run the app in daemon mode and does not listen for user input." <<
+	     endl;
+	cout << "                   This is needed if px4 is intended to be run as a upstart job on linux" << endl;
+	cout << "<data_directory> - directory where ROMFS and posix-configs are located (if not given, CWD is used)" << endl;
+	cout << "<startup_config> - config file for starting/stopping px4 modules" << endl;
+	cout << "   -h            - help/usage information" << endl;
+}
+
+static void process_line(string &line, bool exit_on_fail)
+{
+	vector<string> appargs(20);
+
+	stringstream(line) >> appargs[0] >> appargs[1] >> appargs[2] >> appargs[3] >> appargs[4] >> appargs[5] >> appargs[6] >>
+			   appargs[7] >> appargs[8] >> appargs[9] >> appargs[10] >> appargs[11] >> appargs[12] >> appargs[13] >>
+			   appargs[14] >> appargs[15] >> appargs[16] >> appargs[17] >> appargs[18] >> appargs[19];
+	run_cmd(appargs, exit_on_fail);
+}
+
+static void restore_term()
+{
+	cout << "Restoring terminal\n";
+	tcsetattr(0, TCSANOW, &orig_term);
+}
+
+bool px4_exit_requested(void)
+{
+	return _ExitFlag;
+}
+
+static void set_cpu_scaling()
+{
+#if defined(__PX4_POSIX_EAGLE) || defined(__PX4_POSIX_EXCELSIOR)
+	// On Snapdragon we miss updates in sdlog2 unless all 4 CPUs are run
+	// at the maximum frequency all the time.
+	// Interestingely, cpu0 and cpu3 set the scaling for all 4 CPUs on Snapdragon.
+	system("echo performance > /sys/devices/system/cpu/cpu0/cpufreq/scaling_governor");
+	system("echo performance > /sys/devices/system/cpu/cpu3/cpufreq/scaling_governor");
+
+	// Alternatively we could also raise the minimum frequency to save some power,
+	// unfortunately this still lead to some drops.
+	//system("echo 1190400 > /sys/devices/system/cpu/cpu0/cpufreq/scaling_min_freq");
+#endif
+}
+
+#ifdef __PX4_SITL_MAIN_OVERRIDE
+int SITL_MAIN(int argc, char **argv);
+
+int SITL_MAIN(int argc, char **argv)
+#else
+int main(int argc, char **argv)
+#endif
+{
+	bool daemon_mode = false;
+	bool chroot_on = false;
+
+	tcgetattr(0, &orig_term);
+	atexit(restore_term);
+
+	struct sigaction sig_int;
+	memset(&sig_int, 0, sizeof(struct sigaction));
+	sig_int.sa_handler = _SigIntHandler;
+	sig_int.sa_flags = 0;// not SA_RESTART!;
+
+	struct sigaction sig_fpe;
+	memset(&sig_fpe, 0, sizeof(struct sigaction));
+	sig_fpe.sa_handler = _SigFpeHandler;
+	sig_fpe.sa_flags = 0;// not SA_RESTART!;
+
+	sigaction(SIGINT, &sig_int, nullptr);
+	//sigaction(SIGTERM, &sig_int, NULL);
+	sigaction(SIGFPE, &sig_fpe, nullptr);
+
+	set_cpu_scaling();
+
+	int index = 1;
+	string  commands_file;
+	int positional_arg_count = 0;
+	string data_path;
+	string node_name;
+
+	// parse arguments
+	while (index < argc) {
+		//cout << "arg: " << index << " : " << argv[index] << endl;
+
+		if (argv[index][0] == '-') {
+			// the arg starts with -
+			if (strncmp(argv[index], "-d", 2) == 0) {
+				daemon_mode = true;
+
+			} else if (strncmp(argv[index], "-h", 2) == 0) {
+				usage();
+				return 0;
+
+			} else if (strncmp(argv[index], "-c", 2) == 0) {
+				chroot_on = true;
+
+			} else {
+				PX4_ERR("Unknown/unhandled parameter: %s", argv[index]);
+				return 1;
+			}
+
+		} else if (!strncmp(argv[index], "__", 2)) {
+			//cout << "ros argument" << endl;
+
+			// ros arguments
+			if (!strncmp(argv[index], "__name:=", 8)) {
+				string name_arg = argv[index];
+				node_name = name_arg.substr(8);
+				cout << "node name: " << node_name << endl;
+			}
+
+		} else {
+			//cout << "positional argument" << endl;
+
+			positional_arg_count += 1;
+
+			if (positional_arg_count == 1) {
+				data_path = argv[index];
+
+			} else if (positional_arg_count == 2) {
+				commands_file = argv[index];
+			}
+		}
+
+		++index;
+	}
+
+	if (positional_arg_count != 2 && positional_arg_count != 1) {
+		PX4_ERR("Error expected 1 or 2 position arguments, got %d", positional_arg_count);
+		usage();
+		return -1;
+	}
+
+	bool symlinks_needed = true;
+
+	if (positional_arg_count == 1) { //data path is optional
+		commands_file = data_path;
+		symlinks_needed = false;
+
+	} else {
+		cout << "data path: " << data_path << endl;
+	}
+
+	cout << "commands file: " << commands_file << endl;
+
+	if (commands_file.empty()) {
+		PX4_ERR("Error commands file not specified");
+		return -1;
+	}
+
+	if (!fileExists(commands_file)) {
+		PX4_ERR("Error opening commands file, does not exist: %s", commands_file.c_str());
+		return -1;
+	}
+
+	// create sym-links
+	if (symlinks_needed) {
+		vector<string> path_sym_links;
+		path_sym_links.push_back("ROMFS");
+		path_sym_links.push_back("posix-configs");
+		path_sym_links.push_back("test_data");
+
+		for (unsigned i = 0; i < path_sym_links.size(); i++) {
+			string path_sym_link = path_sym_links[i];
+			//cout << "path sym link: " << path_sym_link << endl;
+			string src_path = data_path + "/" + path_sym_link;
+			string dest_path =  pwd() + "/" +  path_sym_link;
+
+			PX4_DEBUG("Creating symlink %s -> %s", src_path.c_str(), dest_path.c_str());
+
+			if (dirExists(path_sym_link)) { continue; }
+
+			// create sym-links
+			int ret = symlink(src_path.c_str(), dest_path.c_str());
+
+			if (ret != 0) {
+				PX4_ERR("Error creating symlink %s -> %s",
+					src_path.c_str(), dest_path.c_str());
+				return ret;
+
+			} else {
+				PX4_DEBUG("Successfully created symlink %s -> %s",
+					  src_path.c_str(), dest_path.c_str());
+			}
+		}
+	}
+
+	// setup rootfs
+	const string eeprom_path = "./rootfs/eeprom/";
+	const string microsd_path = "./rootfs/fs/microsd/";
+
+	if (!fileExists(eeprom_path + "parameters")) {
+		cout << "creating new parameters file" << endl;
+		mkpath(eeprom_path.c_str(), S_IRUSR | S_IWUSR | S_IXUSR);
+		touch(eeprom_path + "parameters");
+	}
+
+	if (!fileExists(microsd_path + "dataman")) {
+		cout << "creating new dataman file" << endl;
+		mkpath(microsd_path.c_str(), S_IRUSR | S_IWUSR | S_IXUSR);
+		touch(microsd_path + "dataman");
+	}
+
+	// initialize
+	DriverFramework::Framework::initialize();
+	px4::init_once();
+
+	px4::init(argc, argv, "px4");
+
+	// if commandfile is present, process the commands from the file
+	if (!commands_file.empty()) {
+		ifstream infile(commands_file.c_str());
+
+		if (infile.is_open()) {
+			for (string line; getline(infile, line, '\n');) {
+
+				if (px4_exit_requested()) {
+					break;
+				}
+
+				// TODO: this should be true but for that we have to check all startup files
+				process_line(line, false);
+			}
+
+		} else {
+			PX4_ERR("Error opening commands file: %s", commands_file.c_str());
+		}
+	}
+
+	if (chroot_on) {
+		// Lock this application in the current working dir
+		// this is not an attempt to secure the environment,
+		// rather, to replicate a deployed file system.
+
+		char pwd_path[path_max_len];
+		const char *folderpath = "/rootfs/";
+
+		if (nullptr == getcwd(pwd_path, sizeof(pwd_path))) {
+			PX4_ERR("Failed acquiring working dir, abort.");
+			exit(1);
+		}
+
+		if (nullptr == strcat(pwd_path, folderpath)) {
+			PX4_ERR("Failed completing path, abort.");
+			exit(1);
+		}
+
+		if (chroot(pwd_path)) {
+			PX4_ERR("Failed chrooting application, path: %s, error: %s.", pwd_path, strerror(errno));
+			exit(1);
+		}
+
+		if (chdir("/")) {
+			PX4_ERR("Failed changing to root dir, path: %s, error: %s.", pwd_path, strerror(errno));
+			exit(1);
+		}
+	}
+
+	if (!daemon_mode) {
+		string mystr;
+		string string_buffer[CMD_BUFF_SIZE];
+		int buf_ptr_write = 0;
+		int buf_ptr_read = 0;
+		uint8_t cursor_position =
+			0; // position of the cursor from right to left (0: all the way to the right, mystr.length: all the way to the left)
+
+		print_prompt();
+
+		// change input mode so that we can manage shell
+		struct termios term;
+		tcgetattr(0, &term);
+		term.c_lflag &= ~ICANON;
+		term.c_lflag &= ~ECHO;
+		tcsetattr(0, TCSANOW, &term);
+		setbuf(stdin, nullptr);
+
+		while (!_ExitFlag) {
+
+			char c = getchar();
+			string add_string; // string to add at current cursor position
+			bool update_prompt = true;
+
+			switch (c) {
+			case 127:	// backslash
+				if (mystr.length() - cursor_position > 0) {
+					mystr.erase(mystr.length() - cursor_position - 1, 1);
+
+				}
+
+				break;
+
+			case '\n':	// user hit enter
+				if (buf_ptr_write == CMD_BUFF_SIZE) {
+					buf_ptr_write = 0;
+				}
+
+				if (buf_ptr_write > 0) {
+					if (!mystr.empty() && mystr != string_buffer[buf_ptr_write - 1]) {
+						string_buffer[buf_ptr_write] = mystr;
+						buf_ptr_write++;
+					}
+
+				} else {
+					if (!mystr.empty() && mystr != string_buffer[CMD_BUFF_SIZE - 1]) {
+						string_buffer[buf_ptr_write] = mystr;
+						buf_ptr_write++;
+					}
+				}
+
+				cout << endl;
+				process_line(mystr, false);
+				// reset string and cursor position
+				mystr = "";
+				cursor_position = 0;
+				buf_ptr_read = buf_ptr_write;
+
+				print_prompt();
+				break;
+
+			case '\033': {	// arrow keys
+					c = getchar();	// skip first one, does not have the info
+					c = getchar();
+
+					if (c == 'A') { // arrow up
+						buf_ptr_read--;
+
+					} else if (c == 'B') { // arrow down
+						if (buf_ptr_read < buf_ptr_write) {
+							buf_ptr_read++;
+						}
+
+					} else if (c == 'C') { // arrow right
+						if (cursor_position > 0) {
+							printf("\033[1C");
+							cursor_position--;
+						}
+
+						break;
+
+					} else if (c == 'D') { // arrow left
+						if (cursor_position < mystr.length()) {
+							printf("\033[1D");
+							cursor_position++;
+						}
+
+						break;
+
+					} else if (c == 'H') { // Home (go to the beginning of the command)
+						cursor_position = mystr.length();
+						break;
+
+					} else if (c == '1') { // Home (go to the beginning of the command, Editing key)
+						(void)getchar(); // swallow '~'
+						cursor_position = mystr.length();
+						break;
+
+					} else if (c == 'F') { // End (go to the end of the command)
+						cursor_position = 0;
+						break;
+
+					} else if (c == '4') { // End (go to the end of the command, Editing key)
+						(void)getchar(); // swallow '~'
+						cursor_position = 0;
+						break;
+					}
+
+					if (buf_ptr_read < 0) {
+						buf_ptr_read = 0;
+					}
+
+					string saved_cmd = string_buffer[buf_ptr_read];
+					mystr = saved_cmd;
+					cursor_position = 0; // move cursor to end of line
+
+					break;
+				}
+
+			default:	// any other input
+				if (c > 3) {
+					add_string += c;
+
+				} else {
+					update_prompt = false;
+				}
+
+				break;
+			}
+
+			if (update_prompt) {
+				// reprint prompt with mystr
+				mystr.insert(mystr.length() - cursor_position, add_string);
+				printf("%c[2K", 27);
+				cout << (char)13;
+				print_prompt();
+				cout << mystr;
+
+				// Move the cursor to its position
+				if (cursor_position > 0) {
+					printf("\033[%dD", cursor_position);
+				}
+			}
+
+		}
+
+	} else {
+		while (!_ExitFlag) {
+			usleep(100000);
+		}
+	}
+
+	// TODO: Always try to stop muorb for QURT because px4_task_is_running doesn't seem to work.
+	if (true) {
+		//if (px4_task_is_running("muorb")) {
+		// sending muorb stop is needed if it is running to exit cleanly
+		vector<string> muorb_stop_cmd = { "muorb", "stop" };
+		run_cmd(muorb_stop_cmd, !daemon_mode, true);
+	}
+
+	vector<string> shutdown_cmd = { "shutdown" };
+	run_cmd(shutdown_cmd, true);
+	DriverFramework::Framework::shutdown();
+
+	return OK;
+}
+
+/* vim: set noet fenc=utf-8 ff=unix sts=0 sw=4 ts=4 : */
--- a/platforms/posix/src/px4_layer/CMakeLists.txt
+++ b/platforms/posix/src/px4_layer/CMakeLists.txt
@@ -0,0 +1,61 @@
+############################################################################
+#
+#   Copyright (c) 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
+# 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.
+#
+############################################################################
+
+set(EXTRA_DEPENDS)
+if("${CONFIG_SHMEM}" STREQUAL "1")
+	set(CMAKE_MODULE_PATH ${CMAKE_MODULE_PATH} "${PX4_SOURCE_DIR}/cmake/cmake_hexagon")
+	include(hexagon_sdk)
+	include_directories(${HEXAGON_SDK_INCLUDES})
+	include_directories(${PX4_BINARY_DIR}/platforms/posix)
+	list(APPEND SHMEM_SRCS
+		shmem_posix.c
+	)
+	# TODO: This didn't seem to be tracked correctly from posix_eagle_release.cmake
+	set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -DCONFIG_SHMEM")
+	set(EXTRA_DEPENDS generate_px4muorb_stubs)
+endif()
+
+px4_add_module(
+	MODULE platforms__posix__px4_layer
+	COMPILE_FLAGS
+	SRCS
+		px4_posix_impl.cpp
+		px4_posix_tasks.cpp
+		px4_sem.cpp
+		lib_crc32.c
+		drv_hrt.c
+		${SHMEM_SRCS}
+	DEPENDS
+		platforms__common
+		${EXTRA_DEPENDS}
+	)
--- a/platforms/posix/src/px4_layer/drv_hrt.c
+++ b/platforms/posix/src/px4_layer/drv_hrt.c
@@ -0,0 +1,603 @@
+/****************************************************************************
+ *
+ *   Copyright (c) 2012, 2013 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 drv_hrt.c
+ *
+ * High-resolution timer with callouts and timekeeping.
+ */
+
+#include <px4_time.h>
+#include <px4_posix.h>
+#include <px4_defines.h>
+#include <px4_workqueue.h>
+#include <px4_tasks.h>
+#include <drivers/drv_hrt.h>
+#include <semaphore.h>
+#include <time.h>
+#include <string.h>
+#include <inttypes.h>
+#include <errno.h>
+#include "hrt_work.h"
+
+static struct sq_queue_s	callout_queue;
+
+/* latency histogram */
+#define LATENCY_BUCKET_COUNT 8
+__EXPORT const uint16_t latency_bucket_count = LATENCY_BUCKET_COUNT;
+__EXPORT const uint16_t	latency_buckets[LATENCY_BUCKET_COUNT] = { 1, 2, 5, 10, 20, 50, 100, 1000 };
+__EXPORT uint32_t	latency_counters[LATENCY_BUCKET_COUNT + 1];
+
+static void		hrt_call_reschedule(void);
+
+// Intervals in usec
+#define HRT_INTERVAL_MIN	50
+#define HRT_INTERVAL_MAX	50000000
+
+static px4_sem_t 	_hrt_lock;
+static struct work_s	_hrt_work;
+#ifndef __PX4_QURT
+static hrt_abstime px4_timestart = 0;
+#else
+static int32_t dsp_offset = 0;
+#endif
+static hrt_abstime _start_delay_time = 0;
+static hrt_abstime _delay_interval = 0;
+static hrt_abstime max_time = 0;
+pthread_mutex_t _hrt_mutex = PTHREAD_MUTEX_INITIALIZER;
+
+static void
+hrt_call_invoke(void);
+
+static hrt_abstime
+_hrt_absolute_time_internal(void);
+
+__EXPORT hrt_abstime hrt_reset(void);
+
+static void hrt_lock(void)
+{
+	px4_sem_wait(&_hrt_lock);
+}
+
+static void hrt_unlock(void)
+{
+	px4_sem_post(&_hrt_lock);
+}
+
+#if defined(__PX4_APPLE_LEGACY)
+#include <sys/time.h>
+
+int px4_clock_gettime(clockid_t clk_id, struct timespec *tp)
+{
+	struct timeval now;
+	int rv = gettimeofday(&now, NULL);
+
+	if (rv) {
+		return rv;
+	}
+
+	tp->tv_sec = now.tv_sec;
+	tp->tv_nsec = now.tv_usec * 1000;
+
+	return 0;
+}
+
+int px4_clock_settime(clockid_t clk_id, struct timespec *tp)
+{
+	/* do nothing right now */
+	return 0;
+}
+
+#elif defined(__PX4_QURT)
+
+#include "dspal_time.h"
+
+int px4_clock_settime(clockid_t clk_id, struct timespec *tp)
+{
+	/* do nothing right now */
+	return 0;
+}
+
+int px4_clock_gettime(clockid_t clk_id, struct timespec *tp)
+{
+	return clock_gettime(clk_id, tp);
+}
+
+#endif
+
+#ifndef __PX4_QURT
+/*
+ * Get system time in us
+ */
+uint64_t hrt_system_time(void)
+{
+	struct timespec ts;
+	px4_clock_gettime(CLOCK_MONOTONIC, &ts);
+	return ts_to_abstime(&ts);
+}
+#endif
+
+/*
+ * Get absolute time.
+ */
+hrt_abstime _hrt_absolute_time_internal(void)
+{
+	struct timespec ts;
+
+#if defined(__PX4_QURT)
+	// Don't use the timestart on the DSP on Snapdragon because we manually
+	// set the px4_timestart using the hrt_set_absolute_time_offset().
+	px4_clock_gettime(CLOCK_MONOTONIC, &ts);
+	return ts_to_abstime(&ts) + dsp_offset;
+
+#elif (defined(__PX4_POSIX_EAGLE) || defined(__PX4_POSIX_EXCELSIOR))
+	// Don't do any offseting on the Linux side on the Snapdragon.
+	px4_clock_gettime(CLOCK_MONOTONIC, &ts);
+	return ts_to_abstime(&ts);
+
+#else
+
+	if (!px4_timestart) {
+		px4_clock_gettime(CLOCK_MONOTONIC, &ts);
+		px4_timestart = ts_to_abstime(&ts);
+	}
+
+	px4_clock_gettime(CLOCK_MONOTONIC, &ts);
+	return ts_to_abstime(&ts) - px4_timestart;
+#endif
+}
+
+#ifdef __PX4_QURT
+int hrt_set_absolute_time_offset(int32_t time_diff_us)
+{
+	dsp_offset = time_diff_us;
+	return 0;
+}
+#endif
+
+/*
+ * Get absolute time.
+ */
+hrt_abstime hrt_absolute_time(void)
+{
+	pthread_mutex_lock(&_hrt_mutex);
+
+	hrt_abstime ret;
+
+	if (_start_delay_time > 0) {
+		ret = _start_delay_time;
+
+	} else {
+		ret = _hrt_absolute_time_internal();
+	}
+
+	ret -= _delay_interval;
+
+	if (ret < max_time) {
+		PX4_ERR("WARNING! TIME IS NEGATIVE! %d vs %d", (int)ret, (int)max_time);
+		ret = max_time;
+	}
+
+	max_time = ret;
+	pthread_mutex_unlock(&_hrt_mutex);
+
+	return ret;
+}
+
+__EXPORT hrt_abstime hrt_reset(void)
+{
+#ifndef __PX4_QURT
+	px4_timestart = 0;
+#endif
+	max_time = 0;
+	return _hrt_absolute_time_internal();
+}
+
+/*
+ * Convert a timespec to absolute time.
+ */
+hrt_abstime ts_to_abstime(struct timespec *ts)
+{
+	hrt_abstime	result;
+
+	result = (hrt_abstime)(ts->tv_sec) * 1000000;
+	result += ts->tv_nsec / 1000;
+
+	return result;
+}
+
+/*
+ * Compute the delta between a timestamp taken in the past
+ * and now.
+ *
+ * This function is safe to use even if the timestamp is updated
+ * by an interrupt during execution.
+ */
+hrt_abstime hrt_elapsed_time(const volatile hrt_abstime *then)
+{
+	hrt_abstime delta = hrt_absolute_time() - *then;
+	return delta;
+}
+
+/*
+ * Store the absolute time in an interrupt-safe fashion.
+ *
+ * This function ensures that the timestamp cannot be seen half-written by an interrupt handler.
+ */
+hrt_abstime hrt_store_absolute_time(volatile hrt_abstime *now)
+{
+	hrt_abstime ts = hrt_absolute_time();
+	return ts;
+}
+
+
+/*
+ * If this returns true, the entry has been invoked and removed from the callout list,
+ * or it has never been entered.
+ *
+ * Always returns false for repeating callouts.
+ */
+bool	hrt_called(struct hrt_call *entry)
+{
+	return (entry->deadline == 0);
+}
+
+/*
+ * Remove the entry from the callout list.
+ */
+void	hrt_cancel(struct hrt_call *entry)
+{
+	hrt_lock();
+	sq_rem(&entry->link, &callout_queue);
+	entry->deadline = 0;
+
+	/* if this is a periodic call being removed by the callout, prevent it from
+	 * being re-entered when the callout returns.
+	 */
+	entry->period = 0;
+	hrt_unlock();
+	// endif
+}
+
+/*
+ * initialise a hrt_call structure
+ */
+void	hrt_call_init(struct hrt_call *entry)
+{
+	memset(entry, 0, sizeof(*entry));
+}
+
+/*
+ * delay a hrt_call_every() periodic call by the given number of
+ * microseconds. This should be called from within the callout to
+ * cause the callout to be re-scheduled for a later time. The periodic
+ * callouts will then continue from that new base time at the
+ * previously specified period.
+ */
+void	hrt_call_delay(struct hrt_call *entry, hrt_abstime delay)
+{
+	entry->deadline = hrt_absolute_time() + delay;
+}
+
+/*
+ * Initialise the HRT.
+ */
+void	hrt_init(void)
+{
+	sq_init(&callout_queue);
+
+	int sem_ret = px4_sem_init(&_hrt_lock, 0, 1);
+
+	if (sem_ret) {
+		PX4_ERR("SEM INIT FAIL: %s", strerror(errno));
+	}
+
+	memset(&_hrt_work, 0, sizeof(_hrt_work));
+}
+
+void	hrt_start_delay()
+{
+	pthread_mutex_lock(&_hrt_mutex);
+	_start_delay_time = _hrt_absolute_time_internal();
+	pthread_mutex_unlock(&_hrt_mutex);
+}
+
+void	hrt_stop_delay_delta(hrt_abstime delta)
+{
+	pthread_mutex_lock(&_hrt_mutex);
+
+	uint64_t delta_measured = _hrt_absolute_time_internal() - _start_delay_time;
+
+	if (delta_measured < delta) {
+		delta = delta_measured;
+	}
+
+	_delay_interval += delta;
+	_start_delay_time = 0;
+
+	pthread_mutex_unlock(&_hrt_mutex);
+
+}
+
+void	hrt_stop_delay()
+{
+	pthread_mutex_lock(&_hrt_mutex);
+	uint64_t delta = _hrt_absolute_time_internal() - _start_delay_time;
+	_delay_interval += delta;
+	_start_delay_time = 0;
+
+	pthread_mutex_unlock(&_hrt_mutex);
+
+}
+
+static void
+hrt_call_enter(struct hrt_call *entry)
+{
+	struct hrt_call	*call, *next;
+
+	//PX4_INFO("hrt_call_enter");
+	call = (struct hrt_call *)sq_peek(&callout_queue);
+
+	if ((call == NULL) || (entry->deadline < call->deadline)) {
+		sq_addfirst(&entry->link, &callout_queue);
+		//if (call != NULL) PX4_INFO("call enter at head, reschedule (%lu %lu)", entry->deadline, call->deadline);
+		/* we changed the next deadline, reschedule the timer event */
+		hrt_call_reschedule();
+
+	} else {
+		do {
+			next = (struct hrt_call *)sq_next(&call->link);
+
+			if ((next == NULL) || (entry->deadline < next->deadline)) {
+				//lldbg("call enter after head\n");
+				sq_addafter(&call->link, &entry->link, &callout_queue);
+				break;
+			}
+		} while ((call = next) != NULL);
+	}
+
+	//PX4_INFO("scheduled");
+}
+
+/**
+ * Timer interrupt handler
+ *
+ * This routine simulates a timer interrupt handler
+ */
+static void
+hrt_tim_isr(void *p)
+{
+
+	//PX4_INFO("hrt_tim_isr");
+	/* run any callouts that have met their deadline */
+	hrt_call_invoke();
+
+	hrt_lock();
+
+	/* and schedule the next interrupt */
+	hrt_call_reschedule();
+
+	hrt_unlock();
+}
+
+/**
+ * Reschedule the next timer interrupt.
+ *
+ * This routine must be called with interrupts disabled.
+ */
+static void
+hrt_call_reschedule()
+{
+	hrt_abstime	now = hrt_absolute_time();
+	hrt_abstime	delay = HRT_INTERVAL_MAX;
+	struct hrt_call	*next = (struct hrt_call *)sq_peek(&callout_queue);
+	hrt_abstime	deadline = now + HRT_INTERVAL_MAX;
+
+	//PX4_INFO("hrt_call_reschedule");
+
+	/*
+	 * Determine what the next deadline will be.
+	 *
+	 * Note that we ensure that this will be within the counter
+	 * period, so that when we truncate all but the low 16 bits
+	 * the next time the compare matches it will be the deadline
+	 * we want.
+	 *
+	 * It is important for accurate timekeeping that the compare
+	 * interrupt fires sufficiently often that the base_time update in
+	 * hrt_absolute_time runs at least once per timer period.
+	 */
+	if (next != NULL) {
+		//lldbg("entry in queue\n");
+		if (next->deadline <= (now + HRT_INTERVAL_MIN)) {
+			//lldbg("pre-expired\n");
+			/* set a minimal deadline so that we call ASAP */
+			delay = HRT_INTERVAL_MIN;
+
+		} else if (next->deadline < deadline) {
+			//lldbg("due soon\n");
+			delay = next->deadline - now;
+		}
+	}
+
+	// There is no timer ISR, so simulate one by putting an event on the
+	// high priority work queue
+
+	// Remove the existing expiry and update with the new expiry
+	hrt_work_cancel(&_hrt_work);
+
+	hrt_work_queue(&_hrt_work, (worker_t)&hrt_tim_isr, NULL, delay);
+}
+
+static void
+hrt_call_internal(struct hrt_call *entry, hrt_abstime deadline, hrt_abstime interval, hrt_callout callout, void *arg)
+{
+	PX4_DEBUG("hrt_call_internal deadline=%lu interval = %lu", deadline, interval);
+	hrt_lock();
+
+	//PX4_INFO("hrt_call_internal after lock");
+	/* if the entry is currently queued, remove it */
+	/* note that we are using a potentially uninitialised
+	   entry->link here, but it is safe as sq_rem() doesn't
+	   dereference the passed node unless it is found in the
+	   list. So we potentially waste a bit of time searching the
+	   queue for the uninitialised entry->link but we don't do
+	   anything actually unsafe.
+	*/
+	if (entry->deadline != 0) {
+		sq_rem(&entry->link, &callout_queue);
+	}
+
+#if 1
+
+	// Use this to debug busy CPU that keeps rescheduling with 0 period time
+	/*if (interval < HRT_INTERVAL_MIN) {*/
+	/*PX4_ERR("hrt_call_internal interval too short: %" PRIu64, interval);*/
+	/*PX4_BACKTRACE();*/
+	/*}*/
+
+#endif
+	entry->deadline = deadline;
+	entry->period = interval;
+	entry->callout = callout;
+	entry->arg = arg;
+
+	hrt_call_enter(entry);
+	hrt_unlock();
+}
+
+/*
+ * Call callout(arg) after delay has elapsed.
+ *
+ * If callout is NULL, this can be used to implement a timeout by testing the call
+ * with hrt_called().
+ */
+void	hrt_call_after(struct hrt_call *entry, hrt_abstime delay, hrt_callout callout, void *arg)
+{
+	//printf("hrt_call_after\n");
+	hrt_call_internal(entry,
+			  hrt_absolute_time() + delay,
+			  0,
+			  callout,
+			  arg);
+}
+
+/*
+ * Call callout(arg) after delay, and then after every interval.
+ *
+ * Note thet the interval is timed between scheduled, not actual, call times, so the call rate may
+ * jitter but should not drift.
+ */
+void	hrt_call_every(struct hrt_call *entry, hrt_abstime delay, hrt_abstime interval, hrt_callout callout, void *arg)
+{
+	hrt_call_internal(entry,
+			  hrt_absolute_time() + delay,
+			  interval,
+			  callout,
+			  arg);
+}
+
+/*
+ * Call callout(arg) at absolute time calltime.
+ */
+void	hrt_call_at(struct hrt_call *entry, hrt_abstime calltime, hrt_callout callout, void *arg)
+{
+	hrt_call_internal(entry, calltime, 0, callout, arg);
+}
+
+#if 0
+/*
+ * Convert absolute time to a timespec.
+ */
+void	abstime_to_ts(struct timespec *ts, hrt_abstime abstime);
+#endif
+
+static void
+hrt_call_invoke(void)
+{
+	struct hrt_call	*call;
+	hrt_abstime deadline;
+
+	hrt_lock();
+
+	while (true) {
+		/* get the current time */
+		hrt_abstime now = hrt_absolute_time();
+
+		call = (struct hrt_call *)sq_peek(&callout_queue);
+
+		if (call == NULL) {
+			break;
+		}
+
+		if (call->deadline > now) {
+			break;
+		}
+
+		sq_rem(&call->link, &callout_queue);
+		//PX4_INFO("call pop");
+
+		/* save the intended deadline for periodic calls */
+		deadline = call->deadline;
+
+		/* zero the deadline, as the call has occurred */
+		call->deadline = 0;
+
+		/* invoke the callout (if there is one) */
+		if (call->callout) {
+			// Unlock so we don't deadlock in callback
+			hrt_unlock();
+
+			//PX4_INFO("call %p: %p(%p)", call, call->callout, call->arg);
+			call->callout(call->arg);
+
+			hrt_lock();
+		}
+
+		/* if the callout has a non-zero period, it has to be re-entered */
+		if (call->period != 0) {
+			// re-check call->deadline to allow for
+			// callouts to re-schedule themselves
+			// using hrt_call_delay()
+			if (call->deadline <= now) {
+				call->deadline = deadline + call->period;
+				//PX4_INFO("call deadline set to %lu now=%lu", call->deadline,  now);
+			}
+
+			hrt_call_enter(call);
+		}
+	}
+
+	hrt_unlock();
+}
+
--- a/platforms/posix/src/px4_layer/lib_crc32.c
+++ b/platforms/posix/src/px4_layer/lib_crc32.c
@@ -0,0 +1,125 @@
+/************************************************************************************************
+ * libc/misc/lib_crc32.c
+ *
+ * This file is a part of NuttX:
+ *
+ *   Copyright (C) 2010-2011 Gregory Nutt. All rights reserved.
+ *
+ * The logic in this file was developed by Gary S. Brown:
+ *
+ *   COPYRIGHT (C) 1986 Gary S. Brown.  You may use this program, or code or tables
+ *   extracted from it, as desired without restriction.
+ *
+ * First, the polynomial itself and its table of feedback terms.  The polynomial is:
+ *
+ *    X^32+X^26+X^23+X^22+X^16+X^12+X^11+X^10+X^8+X^7+X^5+X^4+X^2+X^1+X^0
+ *
+ * Note that we take it "backwards" and put the highest-order term in the lowest-order bit.
+ * The X^32 term is "implied"; the LSB is the X^31 term, etc.  The X^0 term (usually shown
+ * as "+1") results in the MSB being 1
+ *
+ * Note that the usual hardware shift register implementation, which is what we're using
+ * (we're merely optimizing it by doing eight-bit chunks at a time) shifts bits into the
+ * lowest-order term.  In our implementation, that means shifting towards the right.  Why
+ * do we do it this way?  Because the calculated CRC must be transmitted in order from
+ * highest-order term to lowest-order term.  UARTs transmit characters in order from LSB
+ * to MSB.  By storing the CRC this way we hand it to the UART in the order low-byte to
+ * high-byte; the UART sends each low-bit to hight-bit; and the result is transmission bit
+ * by bit from highest- to lowest-order term without requiring any bit shuffling on our
+ * part.  Reception works similarly
+ *
+ * The feedback terms table consists of 256, 32-bit entries.  Notes
+ *
+ * - The table can be generated at runtime if desired; code to do so is shown later.  It
+ *   might not be obvious, but the feedback terms simply represent the results of eight
+ *   shift/xor operations for all combinations of data and CRC register values
+ *
+ * - The values must be right-shifted by eight bits by the updcrc logic; the shift must
+ *   be u_(bring in zeroes).  On some hardware you could probably optimize the shift in
+ *   assembler by using byte-swap instructions polynomial $edb88320
+  ************************************************************************************************/
+
+/************************************************************************************************
+ * Included Files
+ ************************************************************************************************/
+
+#include <sys/types.h>
+#include <stdint.h>
+#include <crc32.h>
+
+// Needed for Linux
+#define FAR
+
+/************************************************************************************************
+ * Private Data
+ ************************************************************************************************/
+
+static const uint32_t crc32_tab[] = {
+	0x00000000, 0x77073096, 0xee0e612c, 0x990951ba, 0x076dc419, 0x706af48f, 0xe963a535, 0x9e6495a3,
+	0x0edb8832, 0x79dcb8a4, 0xe0d5e91e, 0x97d2d988, 0x09b64c2b, 0x7eb17cbd, 0xe7b82d07, 0x90bf1d91,
+	0x1db71064, 0x6ab020f2, 0xf3b97148, 0x84be41de, 0x1adad47d, 0x6ddde4eb, 0xf4d4b551, 0x83d385c7,
+	0x136c9856, 0x646ba8c0, 0xfd62f97a, 0x8a65c9ec, 0x14015c4f, 0x63066cd9, 0xfa0f3d63, 0x8d080df5,
+	0x3b6e20c8, 0x4c69105e, 0xd56041e4, 0xa2677172, 0x3c03e4d1, 0x4b04d447, 0xd20d85fd, 0xa50ab56b,
+	0x35b5a8fa, 0x42b2986c, 0xdbbbc9d6, 0xacbcf940, 0x32d86ce3, 0x45df5c75, 0xdcd60dcf, 0xabd13d59,
+	0x26d930ac, 0x51de003a, 0xc8d75180, 0xbfd06116, 0x21b4f4b5, 0x56b3c423, 0xcfba9599, 0xb8bda50f,
+	0x2802b89e, 0x5f058808, 0xc60cd9b2, 0xb10be924, 0x2f6f7c87, 0x58684c11, 0xc1611dab, 0xb6662d3d,
+	0x76dc4190, 0x01db7106, 0x98d220bc, 0xefd5102a, 0x71b18589, 0x06b6b51f, 0x9fbfe4a5, 0xe8b8d433,
+	0x7807c9a2, 0x0f00f934, 0x9609a88e, 0xe10e9818, 0x7f6a0dbb, 0x086d3d2d, 0x91646c97, 0xe6635c01,
+	0x6b6b51f4, 0x1c6c6162, 0x856530d8, 0xf262004e, 0x6c0695ed, 0x1b01a57b, 0x8208f4c1, 0xf50fc457,
+	0x65b0d9c6, 0x12b7e950, 0x8bbeb8ea, 0xfcb9887c, 0x62dd1ddf, 0x15da2d49, 0x8cd37cf3, 0xfbd44c65,
+	0x4db26158, 0x3ab551ce, 0xa3bc0074, 0xd4bb30e2, 0x4adfa541, 0x3dd895d7, 0xa4d1c46d, 0xd3d6f4fb,
+	0x4369e96a, 0x346ed9fc, 0xad678846, 0xda60b8d0, 0x44042d73, 0x33031de5, 0xaa0a4c5f, 0xdd0d7cc9,
+	0x5005713c, 0x270241aa, 0xbe0b1010, 0xc90c2086, 0x5768b525, 0x206f85b3, 0xb966d409, 0xce61e49f,
+	0x5edef90e, 0x29d9c998, 0xb0d09822, 0xc7d7a8b4, 0x59b33d17, 0x2eb40d81, 0xb7bd5c3b, 0xc0ba6cad,
+	0xedb88320, 0x9abfb3b6, 0x03b6e20c, 0x74b1d29a, 0xead54739, 0x9dd277af, 0x04db2615, 0x73dc1683,
+	0xe3630b12, 0x94643b84, 0x0d6d6a3e, 0x7a6a5aa8, 0xe40ecf0b, 0x9309ff9d, 0x0a00ae27, 0x7d079eb1,
+	0xf00f9344, 0x8708a3d2, 0x1e01f268, 0x6906c2fe, 0xf762575d, 0x806567cb, 0x196c3671, 0x6e6b06e7,
+	0xfed41b76, 0x89d32be0, 0x10da7a5a, 0x67dd4acc, 0xf9b9df6f, 0x8ebeeff9, 0x17b7be43, 0x60b08ed5,
+	0xd6d6a3e8, 0xa1d1937e, 0x38d8c2c4, 0x4fdff252, 0xd1bb67f1, 0xa6bc5767, 0x3fb506dd, 0x48b2364b,
+	0xd80d2bda, 0xaf0a1b4c, 0x36034af6, 0x41047a60, 0xdf60efc3, 0xa867df55, 0x316e8eef, 0x4669be79,
+	0xcb61b38c, 0xbc66831a, 0x256fd2a0, 0x5268e236, 0xcc0c7795, 0xbb0b4703, 0x220216b9, 0x5505262f,
+	0xc5ba3bbe, 0xb2bd0b28, 0x2bb45a92, 0x5cb36a04, 0xc2d7ffa7, 0xb5d0cf31, 0x2cd99e8b, 0x5bdeae1d,
+	0x9b64c2b0, 0xec63f226, 0x756aa39c, 0x026d930a, 0x9c0906a9, 0xeb0e363f, 0x72076785, 0x05005713,
+	0x95bf4a82, 0xe2b87a14, 0x7bb12bae, 0x0cb61b38, 0x92d28e9b, 0xe5d5be0d, 0x7cdcefb7, 0x0bdbdf21,
+	0x86d3d2d4, 0xf1d4e242, 0x68ddb3f8, 0x1fda836e, 0x81be16cd, 0xf6b9265b, 0x6fb077e1, 0x18b74777,
+	0x88085ae6, 0xff0f6a70, 0x66063bca, 0x11010b5c, 0x8f659eff, 0xf862ae69, 0x616bffd3, 0x166ccf45,
+	0xa00ae278, 0xd70dd2ee, 0x4e048354, 0x3903b3c2, 0xa7672661, 0xd06016f7, 0x4969474d, 0x3e6e77db,
+	0xaed16a4a, 0xd9d65adc, 0x40df0b66, 0x37d83bf0, 0xa9bcae53, 0xdebb9ec5, 0x47b2cf7f, 0x30b5ffe9,
+	0xbdbdf21c, 0xcabac28a, 0x53b39330, 0x24b4a3a6, 0xbad03605, 0xcdd70693, 0x54de5729, 0x23d967bf,
+	0xb3667a2e, 0xc4614ab8, 0x5d681b02, 0x2a6f2b94, 0xb40bbe37, 0xc30c8ea1, 0x5a05df1b, 0x2d02ef8d
+};
+
+/************************************************************************************************
+ * Public Functions
+ ************************************************************************************************/
+/************************************************************************************************
+ * Name: crc32part
+ *
+ * Description:
+ *   Continue CRC calculation on a part of the buffer.
+ *
+ ************************************************************************************************/
+
+uint32_t crc32part(FAR const uint8_t *src, size_t len, uint32_t crc32val)
+{
+	size_t i;
+
+	for (i = 0;  i < len;  i++) {
+		crc32val = crc32_tab[(crc32val ^ src[i]) & 0xff] ^ (crc32val >> 8);
+	}
+
+	return crc32val;
+}
+
+/************************************************************************************************
+ * Name: crc32
+ *
+ * Description:
+ *   Return a 32-bit CRC of the contents of the 'src' buffer, length 'len'
+ *
+ ************************************************************************************************/
+
+uint32_t crc32(FAR const uint8_t *src, size_t len)
+{
+	return crc32part(src, len, 0);
+}
--- a/platforms/posix/src/px4_layer/px4_posix_impl.cpp
+++ b/platforms/posix/src/px4_layer/px4_posix_impl.cpp
@@ -0,0 +1,114 @@
+/****************************************************************************
+ *
+ *   Copyright (c) 2015 Mark Charlebois. 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 px4_posix_impl.cpp
+ *
+ * PX4 Middleware Wrapper Linux Implementation
+ */
+
+#include <px4_defines.h>
+#include <px4_middleware.h>
+#include <px4_workqueue.h>
+#include <px4_defines.h>
+#include <stdint.h>
+#include <stdio.h>
+#include <signal.h>
+#include <errno.h>
+#include <unistd.h>
+#include <systemlib/param/param.h>
+#include "hrt_work.h"
+#include <drivers/drv_hrt.h>
+#include "px4_time.h"
+#include <pthread.h>
+
+extern pthread_t _shell_task_id;
+
+__BEGIN_DECLS
+
+long PX4_TICKS_PER_SEC = sysconf(_SC_CLK_TCK);
+
+#ifdef CONFIG_SHMEM
+extern void init_params(void);
+#endif
+
+__END_DECLS
+
+namespace px4
+{
+
+void init_once();
+
+void init_once()
+{
+	_shell_task_id = pthread_self();
+	//printf("[init] shell id: %lu\n", (unsigned long)_shell_task_id);
+	work_queues_init();
+	hrt_work_queue_init();
+	hrt_init();
+	param_init();
+
+#ifdef CONFIG_SHMEM
+	PX4_DEBUG("Syncing params to shared memory\n");
+	init_params();
+#endif
+}
+
+void init(int argc, char *argv[], const char *app_name)
+{
+	printf("\n");
+	printf("______  __   __    ___ \n");
+	printf("| ___ \\ \\ \\ / /   /   |\n");
+	printf("| |_/ /  \\ V /   / /| |\n");
+	printf("|  __/   /   \\  / /_| |\n");
+	printf("| |     / /^\\ \\ \\___  |\n");
+	printf("\\_|     \\/   \\/     |_/\n");
+	printf("\n");
+	printf("%s starting.\n", app_name);
+	printf("\n");
+
+	// set the threads name
+#ifdef __PX4_DARWIN
+	(void)pthread_setname_np(app_name);
+#else
+	(void)pthread_setname_np(pthread_self(), app_name);
+#endif
+}
+
+uint64_t get_time_micros()
+{
+	return hrt_absolute_time();
+}
+
+}
+
--- a/platforms/posix/src/px4_layer/px4_posix_tasks.cpp
+++ b/platforms/posix/src/px4_layer/px4_posix_tasks.cpp
@@ -0,0 +1,451 @@
+/****************************************************************************
+ *
+ *   Copyright (C) 2015 Mark Charlebois. All rights reserved.
+ *   Author: @author Mark Charlebois <charlebm#gmail.com>
+ *
+ * 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 px4_posix_tasks.c
+ * Implementation of existing task API for Linux
+ */
+
+#include <px4_log.h>
+#include <px4_defines.h>
+#include <unistd.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <errno.h>
+#include <stdbool.h>
+#include <signal.h>
+#include <fcntl.h>
+#include <sched.h>
+#include <unistd.h>
+#include <string.h>
+#include <pthread.h>
+#include <limits.h>
+
+#include <sys/stat.h>
+#include <sys/types.h>
+#include <string>
+
+#include <px4_tasks.h>
+#include <px4_posix.h>
+#include <systemlib/err.h>
+
+#define MAX_CMD_LEN 100
+
+#define PX4_MAX_TASKS 50
+#define SHELL_TASK_ID (PX4_MAX_TASKS+1)
+
+pthread_t _shell_task_id = 0;
+pthread_mutex_t task_mutex = PTHREAD_MUTEX_INITIALIZER;
+
+struct task_entry {
+	pthread_t pid;
+	std::string name;
+	bool isused;
+	task_entry() : isused(false) {}
+};
+
+static task_entry taskmap[PX4_MAX_TASKS] = {};
+
+typedef struct {
+	px4_main_t entry;
+	char name[16]; //pthread_setname_np is restricted to 16 chars
+	int argc;
+	char *argv[];
+	// strings are allocated after the struct data
+} pthdata_t;
+
+static void *entry_adapter(void *ptr)
+{
+	pthdata_t *data = (pthdata_t *) ptr;
+
+	int rv;
+
+	// set the threads name
+#ifdef __PX4_DARWIN
+	rv = pthread_setname_np(data->name);
+#else
+	rv = pthread_setname_np(pthread_self(), data->name);
+#endif
+
+	if (rv) {
+		PX4_ERR("px4_task_spawn_cmd: failed to set name of thread %d %d\n", rv, errno);
+	}
+
+	data->entry(data->argc, data->argv);
+	free(ptr);
+	PX4_DEBUG("Before px4_task_exit");
+	px4_task_exit(0);
+	PX4_DEBUG("After px4_task_exit");
+
+	return nullptr;
+}
+
+void
+px4_systemreset(bool to_bootloader)
+{
+	PX4_WARN("Called px4_system_reset");
+	exit(0);
+}
+
+px4_task_t px4_task_spawn_cmd(const char *name, int scheduler, int priority, int stack_size, px4_main_t entry,
+			      char *const argv[])
+{
+
+	int rv;
+	int argc = 0;
+	int i;
+	unsigned int len = 0;
+	unsigned long offset;
+	unsigned long structsize;
+	char *p = (char *)argv;
+
+	pthread_attr_t attr;
+	struct sched_param param = {};
+
+	// Calculate argc
+	while (p != (char *)nullptr) {
+		p = argv[argc];
+
+		if (p == (char *)nullptr) {
+			break;
+		}
+
+		++argc;
+		len += strlen(p) + 1;
+	}
+
+	structsize = sizeof(pthdata_t) + (argc + 1) * sizeof(char *);
+
+	// not safe to pass stack data to the thread creation
+	pthdata_t *taskdata = (pthdata_t *)malloc(structsize + len);
+	memset(taskdata, 0, structsize + len);
+	offset = ((unsigned long)taskdata) + structsize;
+
+	strncpy(taskdata->name, name, 16);
+	taskdata->name[15] = 0;
+	taskdata->entry = entry;
+	taskdata->argc = argc;
+
+	for (i = 0; i < argc; i++) {
+		PX4_DEBUG("arg %d %s\n", i, argv[i]);
+		taskdata->argv[i] = (char *)offset;
+		strcpy((char *)offset, argv[i]);
+		offset += strlen(argv[i]) + 1;
+	}
+
+	// Must add NULL at end of argv
+	taskdata->argv[argc] = (char *)nullptr;
+
+	PX4_DEBUG("starting task %s", name);
+
+	rv = pthread_attr_init(&attr);
+
+	if (rv != 0) {
+		PX4_ERR("px4_task_spawn_cmd: failed to init thread attrs");
+		free(taskdata);
+		return (rv < 0) ? rv : -rv;
+	}
+
+#ifndef __PX4_DARWIN
+
+	if (stack_size < PTHREAD_STACK_MIN) {
+		stack_size = PTHREAD_STACK_MIN;
+	}
+
+	rv = pthread_attr_setstacksize(&attr, PX4_STACK_ADJUSTED(stack_size));
+
+	if (rv != 0) {
+		PX4_ERR("pthread_attr_setstacksize to %d returned error (%d)", stack_size, rv);
+		pthread_attr_destroy(&attr);
+		free(taskdata);
+		return (rv < 0) ? rv : -rv;
+	}
+
+#endif
+
+	rv = pthread_attr_setinheritsched(&attr, PTHREAD_EXPLICIT_SCHED);
+
+	if (rv != 0) {
+		PX4_ERR("px4_task_spawn_cmd: failed to set inherit sched");
+		pthread_attr_destroy(&attr);
+		free(taskdata);
+		return (rv < 0) ? rv : -rv;
+	}
+
+	rv = pthread_attr_setschedpolicy(&attr, scheduler);
+
+	if (rv != 0) {
+		PX4_ERR("px4_task_spawn_cmd: failed to set sched policy");
+		pthread_attr_destroy(&attr);
+		free(taskdata);
+		return (rv < 0) ? rv : -rv;
+	}
+
+#ifdef __PX4_CYGWIN
+	/* Priorities on Windows are defined a lot differently */
+	priority = SCHED_PRIORITY_DEFAULT;
+#endif
+
+	param.sched_priority = priority;
+
+	rv = pthread_attr_setschedparam(&attr, &param);
+
+	if (rv != 0) {
+		PX4_ERR("px4_task_spawn_cmd: failed to set sched param");
+		pthread_attr_destroy(&attr);
+		free(taskdata);
+		return (rv < 0) ? rv : -rv;
+	}
+
+	pthread_mutex_lock(&task_mutex);
+
+	int taskid = 0;
+
+	for (i = 0; i < PX4_MAX_TASKS; ++i) {
+		if (taskmap[i].isused == false) {
+			taskmap[i].name = name;
+			taskmap[i].isused = true;
+			taskid = i;
+			break;
+		}
+	}
+
+	if (i >= PX4_MAX_TASKS) {
+		pthread_attr_destroy(&attr);
+		pthread_mutex_unlock(&task_mutex);
+		free(taskdata);
+		return -ENOSPC;
+	}
+
+	rv = pthread_create(&taskmap[taskid].pid, &attr, &entry_adapter, (void *) taskdata);
+
+	if (rv != 0) {
+
+		if (rv == EPERM) {
+			//printf("WARNING: NOT RUNING AS ROOT, UNABLE TO RUN REALTIME THREADS\n");
+			rv = pthread_create(&taskmap[taskid].pid, nullptr, &entry_adapter, (void *) taskdata);
+
+			if (rv != 0) {
+				PX4_ERR("px4_task_spawn_cmd: failed to create thread %d %d\n", rv, errno);
+				taskmap[taskid].isused = false;
+				pthread_attr_destroy(&attr);
+				pthread_mutex_unlock(&task_mutex);
+				free(taskdata);
+				return (rv < 0) ? rv : -rv;
+			}
+
+		} else {
+			pthread_attr_destroy(&attr);
+			pthread_mutex_unlock(&task_mutex);
+			free(taskdata);
+			return (rv < 0) ? rv : -rv;
+		}
+	}
+
+	pthread_attr_destroy(&attr);
+	pthread_mutex_unlock(&task_mutex);
+
+	return i;
+}
+
+int px4_task_delete(px4_task_t id)
+{
+	int rv = 0;
+	pthread_t pid;
+	PX4_DEBUG("Called px4_task_delete");
+
+	if (id < PX4_MAX_TASKS && taskmap[id].isused) {
+		pid = taskmap[id].pid;
+
+	} else {
+		return -EINVAL;
+	}
+
+	pthread_mutex_lock(&task_mutex);
+
+	// If current thread then exit, otherwise cancel
+	if (pthread_self() == pid) {
+		pthread_join(pid, nullptr);
+		taskmap[id].isused = false;
+		pthread_mutex_unlock(&task_mutex);
+		pthread_exit(nullptr);
+
+	} else {
+		rv = pthread_cancel(pid);
+	}
+
+	taskmap[id].isused = false;
+	pthread_mutex_unlock(&task_mutex);
+
+	return rv;
+}
+
+void px4_task_exit(int ret)
+{
+	int i;
+	pthread_t pid = pthread_self();
+
+	// Get pthread ID from the opaque ID
+	for (i = 0; i < PX4_MAX_TASKS; ++i) {
+		if (taskmap[i].pid == pid) {
+			pthread_mutex_lock(&task_mutex);
+			taskmap[i].isused = false;
+			break;
+		}
+	}
+
+	if (i >= PX4_MAX_TASKS)  {
+		PX4_ERR("px4_task_exit: self task not found!");
+
+	} else {
+		PX4_DEBUG("px4_task_exit: %s", taskmap[i].name.c_str());
+	}
+
+	pthread_mutex_unlock(&task_mutex);
+
+	pthread_exit((void *)(unsigned long)ret);
+}
+
+int px4_task_kill(px4_task_t id, int sig)
+{
+	int rv = 0;
+	pthread_t pid;
+	PX4_DEBUG("Called px4_task_kill %d", sig);
+
+	if (id < PX4_MAX_TASKS && taskmap[id].isused && taskmap[id].pid != 0) {
+		pthread_mutex_lock(&task_mutex);
+		pid = taskmap[id].pid;
+		pthread_mutex_unlock(&task_mutex);
+
+	} else {
+		return -EINVAL;
+	}
+
+	// If current thread then exit, otherwise cancel
+	rv = pthread_kill(pid, sig);
+
+	return rv;
+}
+
+void px4_show_tasks()
+{
+	int idx;
+	int count = 0;
+
+	PX4_INFO("Active Tasks:");
+
+	for (idx = 0; idx < PX4_MAX_TASKS; idx++) {
+		if (taskmap[idx].isused) {
+			PX4_INFO("   %-10s %lu", taskmap[idx].name.c_str(), (unsigned long)taskmap[idx].pid);
+			count++;
+		}
+	}
+
+	if (count == 0) {
+		PX4_INFO("   No running tasks");
+	}
+
+}
+
+bool px4_task_is_running(const char *taskname)
+{
+	int idx;
+
+	for (idx = 0; idx < PX4_MAX_TASKS; idx++) {
+		if (taskmap[idx].isused && (strcmp(taskmap[idx].name.c_str(), taskname) == 0)) {
+			return true;
+		}
+	}
+
+	return false;
+}
+
+px4_task_t px4_getpid()
+{
+	pthread_t pid = pthread_self();
+	px4_task_t ret = -1;
+
+	pthread_mutex_lock(&task_mutex);
+
+	for (int i = 0; i < PX4_MAX_TASKS; i++) {
+		if (taskmap[i].isused && taskmap[i].pid == pid) {
+			ret = i;
+		}
+	}
+
+	pthread_mutex_unlock(&task_mutex);
+	return ret;
+}
+
+const char *px4_get_taskname()
+{
+	pthread_t pid = pthread_self();
+	const char *prog_name = "UnknownApp";
+
+	pthread_mutex_lock(&task_mutex);
+
+	for (int i = 0; i < PX4_MAX_TASKS; i++) {
+		if (taskmap[i].isused && taskmap[i].pid == pid) {
+			prog_name = taskmap[i].name.c_str();
+		}
+	}
+
+	pthread_mutex_unlock(&task_mutex);
+
+	return prog_name;
+}
+
+int px4_prctl(int option, const char *arg2, px4_task_t pid)
+{
+	int rv;
+
+	switch (option) {
+	case PR_SET_NAME:
+		// set the threads name
+#ifdef __PX4_DARWIN
+		rv = pthread_setname_np(arg2);
+#else
+		rv = pthread_setname_np(pthread_self(), arg2);
+#endif
+		break;
+
+	default:
+		rv = -1;
+		PX4_WARN("FAILED SETTING TASK NAME");
+		break;
+	}
+
+	return rv;
+}
+
--- a/platforms/posix/src/px4_layer/px4_sem.cpp
+++ b/platforms/posix/src/px4_layer/px4_sem.cpp
@@ -0,0 +1,205 @@
+/****************************************************************************
+ *
+ *   Copyright (c) 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
+ * 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 px4_sem.cpp
+ *
+ * PX4 Middleware Wrapper Linux Implementation
+ */
+
+#include <px4_defines.h>
+#include <px4_middleware.h>
+#include <px4_workqueue.h>
+#include <stdint.h>
+#include <stdio.h>
+#include <pthread.h>
+#include <errno.h>
+
+#if defined(__PX4_DARWIN) || defined(__PX4_CYGWIN)
+
+#include <px4_posix.h>
+
+int px4_sem_init(px4_sem_t *s, int pshared, unsigned value)
+{
+	// We do not used the process shared arg
+	(void)pshared;
+	s->value = value;
+	pthread_cond_init(&(s->wait), NULL);
+	pthread_mutex_init(&(s->lock), NULL);
+
+	return 0;
+}
+
+int px4_sem_setprotocol(px4_sem_t *s, int protocol)
+{
+	return 0;
+}
+
+int px4_sem_wait(px4_sem_t *s)
+{
+	int ret = pthread_mutex_lock(&(s->lock));
+
+	if (ret) {
+		return ret;
+	}
+
+	s->value--;
+
+	if (s->value < 0) {
+		ret = pthread_cond_wait(&(s->wait), &(s->lock));
+
+	} else {
+		ret = 0;
+	}
+
+	if (ret) {
+		PX4_WARN("px4_sem_wait failure");
+	}
+
+	int mret = pthread_mutex_unlock(&(s->lock));
+
+	return (ret) ? ret : mret;
+}
+
+int px4_sem_trywait(px4_sem_t *s)
+{
+	int ret = pthread_mutex_lock(&(s->lock));
+
+	if (ret) {
+		return ret;
+	}
+
+	if (s->value <= 0) {
+		errno = EAGAIN;
+		ret = -1;
+
+	} else {
+		s->value--;
+	}
+
+	int mret = pthread_mutex_unlock(&(s->lock));
+
+	return (ret) ? ret : mret;
+}
+
+int px4_sem_timedwait(px4_sem_t *s, const struct timespec *abstime)
+{
+	int ret = pthread_mutex_lock(&(s->lock));
+
+	if (ret) {
+		return ret;
+	}
+
+	s->value--;
+	errno = 0;
+
+	if (s->value < 0) {
+		ret = pthread_cond_timedwait(&(s->wait), &(s->lock), abstime);
+
+	} else {
+		ret = 0;
+	}
+
+	int err = ret;
+
+	if (err != 0 && err != ETIMEDOUT) {
+		setbuf(stdout, NULL);
+		setbuf(stderr, NULL);
+		const unsigned NAMELEN = 32;
+		char thread_name[NAMELEN] = {};
+		(void)pthread_getname_np(pthread_self(), thread_name, NAMELEN);
+		PX4_WARN("%s: px4_sem_timedwait failure: ret: %d, %s", thread_name, ret, strerror(err));
+	}
+
+	int mret = pthread_mutex_unlock(&(s->lock));
+
+	return (err) ? err : mret;
+}
+
+int px4_sem_post(px4_sem_t *s)
+{
+	int ret = pthread_mutex_lock(&(s->lock));
+
+	if (ret) {
+		return ret;
+	}
+
+	s->value++;
+
+	if (s->value <= 0) {
+		ret = pthread_cond_signal(&(s->wait));
+
+	} else {
+		ret = 0;
+	}
+
+	if (ret) {
+		PX4_WARN("px4_sem_post failure");
+	}
+
+	int mret = pthread_mutex_unlock(&(s->lock));
+
+	// return the cond signal failure if present,
+	// else return the mutex status
+	return (ret) ? ret : mret;
+}
+
+int px4_sem_getvalue(px4_sem_t *s, int *sval)
+{
+	int ret = pthread_mutex_lock(&(s->lock));
+
+	if (ret) {
+		PX4_WARN("px4_sem_getvalue failure");
+	}
+
+	if (ret) {
+		return ret;
+	}
+
+	*sval = s->value;
+	ret = pthread_mutex_unlock(&(s->lock));
+
+	return ret;
+}
+
+int px4_sem_destroy(px4_sem_t *s)
+{
+	pthread_mutex_lock(&(s->lock));
+	pthread_cond_destroy(&(s->wait));
+	pthread_mutex_unlock(&(s->lock));
+	pthread_mutex_destroy(&(s->lock));
+
+	return 0;
+}
+
+#endif
--- a/platforms/posix/src/px4_layer/shmem_posix.c
+++ b/platforms/posix/src/px4_layer/shmem_posix.c
@@ -0,0 +1,131 @@
+/****************************************************************************
+ *
+ * Copyright (c) 2015 Vijay Venkatraman. 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.
+ *
+ ****************************************************************************/
+
+#include <px4_defines.h>
+#include <px4_posix.h>
+#include <string.h>
+#include <stdbool.h>
+#include <stdlib.h>
+#include <fcntl.h>
+#include <unistd.h>
+#include <systemlib/err.h>
+#include <errno.h>
+#include <semaphore.h>
+
+#include <sys/stat.h>
+
+#include <drivers/drv_hrt.h>
+#include <sys/mman.h>
+#include <sys/ioctl.h>
+
+#include "systemlib/param/param.h"
+
+#include <shmem.h>
+#include "px4muorb.h"
+
+//#define SHMEM_DEBUG
+void update_to_shmem(param_t param, union param_value_u value);
+int update_from_shmem(param_t param, union param_value_u *value);
+void update_index_from_shmem(void);
+uint64_t update_from_shmem_prev_time = 0, update_from_shmem_current_time = 0;
+extern unsigned char *adsp_changed_index;
+
+struct param_wbuf_s {
+	union param_value_u val;
+	param_t param;
+	bool unsaved;
+};
+
+/*update value and param's change bit in shared memory*/
+void update_to_shmem(param_t param, union param_value_u value)
+{
+	if (px4muorb_param_update_to_shmem(param, (unsigned char *) &value,
+					   sizeof(value))) {
+		PX4_ERR("krait update param %u failed", param);
+	}
+}
+
+void update_index_from_shmem(void)
+{
+	if (!adsp_changed_index) {
+		PX4_ERR("%s no param buffer", __FUNCTION__);
+		return;
+	}
+
+	px4muorb_param_update_index_from_shmem(adsp_changed_index,
+					       PARAM_BUFFER_SIZE);
+}
+
+static void update_value_from_shmem(param_t param, union param_value_u *value)
+{
+	if (px4muorb_param_update_value_from_shmem(param, (unsigned char *) value,
+			sizeof(union param_value_u))) {
+		PX4_ERR("%s get param failed", __FUNCTION__);
+	}
+}
+
+int update_from_shmem(param_t param, union param_value_u *value)
+{
+	unsigned int byte_changed, bit_changed;
+	unsigned int retval = 0;
+
+	if (!adsp_changed_index) {
+		PX4_ERR("%s no param buffer", __FUNCTION__);
+		return 0;
+	}
+
+	update_from_shmem_current_time = hrt_absolute_time();
+
+	if ((update_from_shmem_current_time - update_from_shmem_prev_time)
+	    > 1000000) { //update every 1 second
+		update_from_shmem_prev_time = update_from_shmem_current_time;
+		update_index_from_shmem();
+	}
+
+	byte_changed = param / 8;
+	bit_changed = 1 << param % 8;
+
+	if (adsp_changed_index[byte_changed] & bit_changed) {
+		update_value_from_shmem(param, value);
+		adsp_changed_index[byte_changed] &= ~bit_changed; //clear the bit
+		retval = 1;
+	}
+
+	//else {PX4_INFO("no change to param %s", param_name(param));}
+
+	PX4_DEBUG("%s %d bit on adsp index[%d]",
+		  (retval) ? "cleared" : "unchanged", bit_changed, byte_changed);
+
+	return retval;
+}
+
--- a/platforms/posix/src/sitl_runner_main.cpp.in
+++ b/platforms/posix/src/sitl_runner_main.cpp.in
@@ -0,0 +1,53 @@
+/****************************************************************************
+ *
+ *   Copyright (C) 2015 Anton Matosov. 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 sitl_runner_main.cpp
+ * Basic shell to execute px4 with specific model
+ *
+ * @author Anton Matosov <anton.matosov@gmail.com>
+ */
+
+#include <unistd.h>
+
+#define __PX4_SITL_MAIN_OVERRIDE
+#include "@SITL_RUNNER_MAIN_CPP@"
+
+int main(int argc, const char **argv)
+{
+    if (chdir("@SITL_RUNNER_WORKING_DIRECTORY@") != 0) {
+        PX4_ERR("Failed to change current directory to @SITL_RUNNER_WORKING_DIRECTORY@. error %i", errno);
+        return errno;
+    }
+    const char *argsOverride[] = {argv[0], "@SITL_RUNNER_SOURCE_DIR@", "@SITL_RUNNER_MODEL_FILE@"};
+    return SITL_MAIN(sizeof(argsOverride) / sizeof(argsOverride[0]), (char**)argsOverride);
+}