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+############################################################################
+#
+# Copyright (c) 2017 - 2019 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.
+#
+############################################################################
+
+#=============================================================================
+# CMAKE CODING STANDARD FOR PX4
+#
+# Structure
+# ---------------------------------------------------------------------------
+#
+# * Common functions should be included in px_base.cmake.
+#
+# * OS/ board specific fucntions should be include in
+#	px_impl_${PX4_PLATFORM}.cmake or px4_impl_${PX4_PLATFORM}_${PX4_BOARD}.cmake.
+#
+# Formatting
+# ---------------------------------------------------------------------------
+#
+# * Use hard indents to match the px4 source code.
+#
+# * All function and script arguments are upper case.
+#
+# * All local variables are lower case.
+#
+# * All cmake functions are lowercase.
+#
+# * For else, endif, endfunction, etc, never put the name of the statement
+#
+# Functions/Macros
+# ---------------------------------------------------------------------------
+#
+# * Use px4_parse_function_args to parse functions and check for required
+#   arguments. Unless there is only one argument in the function and it is clear.
+#
+# * Never use macros. They allow overwriting global variables and this
+#	makes variable declarations hard to locate.
+#
+# * If a target from add_custom_* is set in a function, explicitly pass it
+#	as an output argument so that the target name is clear to the user.
+#
+# * Avoid use of global variables in functions. Functions in a nested
+#	scope may use global variables, but this makes it difficult to
+#	reuse functions.
+#
+# Included CMake Files
+# ---------------------------------------------------------------------------
+#
+# * All variables in config files must have the prefix "config_".
+#
+# * Never set global variables in an included cmake file,
+#	you may only define functions. This excludes config and Toolchain files.
+#	This makes it clear to the user when variables are being set or targets
+#	are being created.
+#
+# * Setting a global variable in a CMakeLists.txt file is ok, because
+#	each CMakeLists.txt file has scope in the current directory and all
+#	subdirectories, so it is not truly global.
+#
+# * All toolchain files should be included in the cmake
+#	directory and named Toolchain-"name".cmake.
+#
+# Misc
+# ---------------------------------------------------------------------------
+#
+# * If referencing a string variable, don't put it in quotes.
+#	Don't do "${PX4_PLATFORM}" STREQUAL "posix",
+#	instead type ${PX4_PLATFORM} STREQUAL "posix". This will throw an
+#	error when ${PX4_PLATFORM} is not defined instead of silently
+#	evaluating to false.
+#
+#=============================================================================
+
+cmake_minimum_required(VERSION 3.2 FATAL_ERROR)
+
+set(PX4_SOURCE_DIR "${CMAKE_CURRENT_SOURCE_DIR}")
+set(PX4_BINARY_DIR "${CMAKE_CURRENT_BINARY_DIR}")
+
+list(APPEND CMAKE_MODULE_PATH ${PX4_SOURCE_DIR}/cmake)
+include(px4_parse_function_args)
+
+#=============================================================================
+# git
+#
+include(px4_git)
+
+execute_process(
+	COMMAND git describe --exclude ext/* --always --tags
+	OUTPUT_VARIABLE PX4_GIT_TAG
+	OUTPUT_STRIP_TRAILING_WHITESPACE
+	WORKING_DIRECTORY ${PX4_SOURCE_DIR}
+	)
+message(STATUS "PX4 version: ${PX4_GIT_TAG}")
+
+define_property(GLOBAL PROPERTY PX4_MODULE_LIBRARIES
+                 BRIEF_DOCS "PX4 module libs"
+                 FULL_DOCS "List of all PX4 module libraries"
+                 )
+
+define_property(GLOBAL PROPERTY PX4_MODULE_PATHS
+                 BRIEF_DOCS "PX4 module paths"
+                 FULL_DOCS "List of paths to all PX4 modules"
+                 )
+
+#=============================================================================
+# configuration
+#
+
+set(CONFIG "px4_sitl_default" CACHE STRING "desired configuration")
+
+include(px4_add_module)
+set(config_module_list)
+
+include(px4_config)
+include(px4_add_board)
+include(${PX4_CONFIG_FILE})
+message(STATUS "PX4 config: ${PX4_CONFIG}")
+message(STATUS "PX4 platform: ${PX4_PLATFORM}")
+
+if(${PX4_PLATFORM} STREQUAL "posix")
+	if(ENABLE_LOCKSTEP_SCHEDULER)
+		add_definitions(-DENABLE_LOCKSTEP_SCHEDULER)
+		message(STATUS "PX4 lockstep: enabled")
+	else()
+		message(STATUS "PX4 lockstep: disabled")
+	endif()
+endif()
+
+# external modules
+set(EXTERNAL_MODULES_LOCATION "" CACHE STRING "External modules source location")
+
+if(NOT EXTERNAL_MODULES_LOCATION STREQUAL "")
+	get_filename_component(EXTERNAL_MODULES_LOCATION "${EXTERNAL_MODULES_LOCATION}" ABSOLUTE)
+endif()
+
+set_property(GLOBAL PROPERTY PX4_MODULE_CONFIG_FILES)
+
+include(platforms/${PX4_PLATFORM}/cmake/px4_impl_os.cmake)
+list(APPEND CMAKE_MODULE_PATH ${PX4_SOURCE_DIR}/platforms/${PX4_PLATFORM}/cmake)
+
+if(EXISTS "${PX4_SOURCE_DIR}/platforms/${PX4_PLATFORM}/cmake/init.cmake")
+	include(init)
+endif()
+
+# CMake build type (Debug Release RelWithDebInfo MinSizeRel Coverage)
+if(NOT CMAKE_BUILD_TYPE)
+	if(${PX4_PLATFORM} STREQUAL "nuttx")
+		set(PX4_BUILD_TYPE "MinSizeRel")
+	else()
+		set(PX4_BUILD_TYPE "RelWithDebInfo")
+	endif()
+
+	set(CMAKE_BUILD_TYPE ${PX4_BUILD_TYPE} CACHE STRING "Build type" FORCE)
+endif()
+
+if((CMAKE_BUILD_TYPE STREQUAL "Debug") OR (CMAKE_BUILD_TYPE STREQUAL "Coverage"))
+	set(MAX_CUSTOM_OPT_LEVEL -O0)
+elseif(CMAKE_BUILD_TYPE MATCHES "Sanitizer")
+	set(MAX_CUSTOM_OPT_LEVEL -O1)
+elseif(CMAKE_BUILD_TYPE MATCHES "Release")
+	set(MAX_CUSTOM_OPT_LEVEL -O3)
+else()
+	if(px4_constrained_flash_build)
+		set(MAX_CUSTOM_OPT_LEVEL -Os)
+	else()
+		set(MAX_CUSTOM_OPT_LEVEL -O2)
+	endif()
+endif()
+
+set_property(CACHE CMAKE_BUILD_TYPE PROPERTY STRINGS "Debug;Release;RelWithDebInfo;MinSizeRel;Coverage;AddressSanitizer;UndefinedBehaviorSanitizer")
+message(STATUS "cmake build type: ${CMAKE_BUILD_TYPE}")
+
+#=============================================================================
+# project definition
+#
+project(px4 CXX C ASM)
+
+set(package-contact "px4users@googlegroups.com")
+
+set(CMAKE_CXX_STANDARD 14)
+set(CMAKE_CXX_STANDARD_REQUIRED ON)
+set(CMAKE_C_STANDARD 11)
+set(CMAKE_C_STANDARD_REQUIRED ON)
+set(CMAKE_EXPORT_COMPILE_COMMANDS ON)
+
+# For the catkin build process, unset build of dynamically-linked binaries
+# and do not change CMAKE_RUNTIME_OUTPUT_DIRECTORY
+if (NOT CATKIN_DEVEL_PREFIX)
+	set(CMAKE_RUNTIME_OUTPUT_DIRECTORY ${PX4_BINARY_DIR})
+	set(CMAKE_RUNTIME_OUTPUT_DIRECTORY_DEBUG ${PX4_BINARY_DIR})
+	set(CMAKE_RUNTIME_OUTPUT_DIRECTORY_RELEASE ${PX4_BINARY_DIR})
+else()
+	SET(BUILD_SHARED_LIBS OFF)
+endif()
+
+#=============================================================================
+
+# gold linker - use if available (posix only for now)
+if(${PX4_PLATFORM} STREQUAL "posix")
+	include(CMakeDependentOption)
+	CMAKE_DEPENDENT_OPTION(USE_LD_GOLD
+			"Use GNU gold linker" ON
+			"NOT WIN32;NOT APPLE" OFF
+	)
+
+	if(USE_LD_GOLD)
+		execute_process(COMMAND ${CMAKE_C_COMPILER} -fuse-ld=gold -Wl,--version ERROR_QUIET OUTPUT_VARIABLE LD_VERSION)
+		if("${LD_VERSION}" MATCHES "GNU gold")
+			set(CMAKE_EXE_LINKER_FLAGS "${CMAKE_EXE_LINKER_FLAGS} -lcrypto -fuse-ld=gold")
+			set(CMAKE_SHARED_LINKER_FLAGS "${CMAKE_SHARED_LINKER_FLAGS} -lcrypto -fuse-ld=gold")
+		else()
+			set(USE_LD_GOLD OFF)
+		endif()
+	endif()
+endif()
+
+#=============================================================================
+
+# Setup install paths
+if(${PX4_PLATFORM} STREQUAL "posix")
+	# This makes it possible to dynamically load code which depends on symbols
+	# inside the px4 executable.
+	set(CMAKE_POSITION_INDEPENDENT_CODE ON)
+	set(CMAKE_ENABLE_EXPORTS ON)
+
+	include(coverage)
+	include(sanitizers)
+
+	# Define GNU standard installation directories
+	include(GNUInstallDirs)
+
+	if (NOT CMAKE_INSTALL_PREFIX)
+		set(CMAKE_INSTALL_PREFIX "/usr" CACHE PATH "Install path prefix" FORCE)
+	endif()
+endif()
+
+include(ccache)
+
+#=============================================================================
+# find programs and packages
+#
+
+# see if catkin was invoked to build this
+if (CATKIN_DEVEL_PREFIX)
+	message(STATUS "catkin ENABLED")
+	find_package(catkin REQUIRED)
+	if (catkin_FOUND)
+		catkin_package()
+	else()
+		message(FATAL_ERROR "catkin not found")
+	endif()
+endif()
+
+# Python
+# If using catkin, Python 2 is found since it points
+# to the Python libs installed with the ROS distro
+if (NOT CATKIN_DEVEL_PREFIX)
+	find_package(PythonInterp 3)
+	# We have a custom error message to tell users how to install python3.
+	if (NOT PYTHONINTERP_FOUND)
+		message(FATAL_ERROR "Python 3 not found. Please install Python 3:\n"
+			"    Ubuntu: sudo apt install python3 python3-dev python3-pip\n"
+			"    macOS: brew install python")
+	endif()
+else()
+	find_package(PythonInterp REQUIRED)
+endif()
+
+option(PYTHON_COVERAGE "Python code coverage" OFF)
+if(PYTHON_COVERAGE)
+	message(STATUS "python coverage enabled")
+	set(PYTHON_EXECUTABLE coverage run -p)
+endif()
+
+#=============================================================================
+# get chip and chip manufacturer
+#
+px4_os_determine_build_chip()
+if(NOT PX4_CHIP_MANUFACTURER)
+	message(FATAL_ERROR "px4_os_determine_build_chip() needs to set PX4_CHIP_MANUFACTURER")
+endif()
+if(NOT PX4_CHIP)
+	message(FATAL_ERROR "px4_os_determine_build_chip() needs to set PX4_CHIP")
+endif()
+
+#=============================================================================
+# build flags
+#
+include(px4_add_common_flags)
+px4_add_common_flags()
+px4_os_add_flags()
+
+#=============================================================================
+# board cmake init (optional)
+#
+if(EXISTS ${PX4_BOARD_DIR}/cmake/init.cmake)
+	include(${PX4_BOARD_DIR}/cmake/init.cmake)
+endif()
+
+#=============================================================================
+# message, and airframe generation
+#
+include(px4_metadata)
+
+add_subdirectory(msg EXCLUDE_FROM_ALL)
+
+px4_generate_airframes_xml(BOARD ${PX4_BOARD})
+
+#=============================================================================
+# external projects
+#
+set(ep_base ${PX4_BINARY_DIR}/external)
+set_property(DIRECTORY PROPERTY EP_BASE ${ep_base})
+
+# add external project install folders to build
+# add the directories so cmake won't warn
+execute_process(COMMAND ${CMAKE_COMMAND} -E make_directory ${ep_base})
+execute_process(COMMAND ${CMAKE_COMMAND} -E make_directory ${ep_base}/Install)
+execute_process(COMMAND ${CMAKE_COMMAND} -E make_directory ${ep_base}/Install/lib)
+link_directories(${ep_base}/Install/lib)
+execute_process(COMMAND ${CMAKE_COMMAND} -E make_directory ${ep_base}/Install/include)
+include_directories(${ep_base}/Install/include)
+
+#=============================================================================
+# external modules
+#
+set(external_module_paths)
+if (NOT EXTERNAL_MODULES_LOCATION STREQUAL "")
+	message(STATUS "External modules: ${EXTERNAL_MODULES_LOCATION}")
+	add_subdirectory("${EXTERNAL_MODULES_LOCATION}/src" external_modules)
+
+	foreach(external_module ${config_module_list_external})
+		add_subdirectory(${EXTERNAL_MODULES_LOCATION}/src/${external_module} external_modules/${external_module})
+		list(APPEND external_module_paths ${EXTERNAL_MODULES_LOCATION}/src/${external_module})
+	endforeach()
+endif()
+
+#=============================================================================
+# Testing - Automatic unit and integration testing with CTest
+#
+
+# optionally enable cmake testing (supported only on posix)
+option(CMAKE_TESTING "Configure test targets" OFF)
+if(${PX4_CONFIG} STREQUAL "px4_sitl_test")
+	set(CMAKE_TESTING ON)
+endif()
+if(CMAKE_TESTING)
+	include(CTest) # sets BUILD_TESTING variable
+endif()
+
+# enable test filtering to run only specific tests with the ctest -R regex functionality
+set(TESTFILTER "" CACHE STRING "Filter string for ctest to selectively only run specific tests (ctest -R)")
+
+# if testing is enabled download and configure gtest
+list(APPEND CMAKE_MODULE_PATH ${PX4_SOURCE_DIR}/cmake/gtest/)
+include(px4_add_gtest)
+if(BUILD_TESTING)
+	include(gtest)
+
+	add_custom_target(test_results
+			COMMAND GTEST_COLOR=1 ${CMAKE_CTEST_COMMAND} --output-on-failure -T Test -R ${TESTFILTER} USES_TERMINAL
+			DEPENDS
+				px4
+				examples__dyn_hello
+				test_mixer_multirotor
+			USES_TERMINAL
+			COMMENT "Running tests"
+			WORKING_DIRECTORY ${PX4_BINARY_DIR})
+	set_target_properties(test_results PROPERTIES EXCLUDE_FROM_ALL TRUE)
+endif()
+
+
+#=============================================================================
+# subdirectories
+#
+add_library(parameters_interface INTERFACE)
+
+include(px4_add_library)
+add_subdirectory(src/lib EXCLUDE_FROM_ALL)
+
+add_subdirectory(platforms/${PX4_PLATFORM}/src/px4)
+add_subdirectory(platforms EXCLUDE_FROM_ALL)
+
+if(EXISTS "${PX4_BOARD_DIR}/CMakeLists.txt")
+	add_subdirectory(${PX4_BOARD_DIR})
+endif()
+
+foreach(module ${config_module_list})
+	add_subdirectory(src/${module})
+endforeach()
+
+# must be the last module before firmware
+add_subdirectory(src/lib/parameters EXCLUDE_FROM_ALL)
+target_link_libraries(parameters_interface INTERFACE parameters)
+
+# firmware added last to generate the builtin for included modules
+add_subdirectory(platforms/${PX4_PLATFORM})
+
+#=============================================================================
+# uORB graph generation: add a custom target 'uorb_graph'
+#
+set(uorb_graph_config ${PX4_BOARD})
+
+set(graph_module_list "")
+foreach(module ${config_module_list})
+	set(graph_module_list "${graph_module_list}" "--src-path" "src/${module}")
+endforeach()
+
+add_custom_command(OUTPUT ${uorb_graph_config}
+	COMMAND ${PYTHON_EXECUTABLE} ${PX4_SOURCE_DIR}/Tools/uorb_graph/create.py
+		${graph_module_list}
+		--exclude-path src/examples
+		--file ${PX4_SOURCE_DIR}/Tools/uorb_graph/graph_${uorb_graph_config}
+	WORKING_DIRECTORY ${PX4_SOURCE_DIR}
+	COMMENT "Generating uORB graph"
+)
+add_custom_target(uorb_graph DEPENDS ${uorb_graph_config})
+
+
+include(doxygen)
+include(metadata)
+include(package)
+
+# print size
+add_custom_target(size
+	COMMAND size $<TARGET_FILE:px4>
+	DEPENDS px4
+	WORKING_DIRECTORY ${PX4_BINARY_DIR}
+	USES_TERMINAL
+	)
+
+# install python requirements using configured python
+add_custom_target(install_python_requirements
+	COMMAND ${PYTHON_EXECUTABLE} -m pip install --requirement ${PX4_SOURCE_DIR}/Tools/setup/requirements.txt
+	DEPENDS ${PX4_SOURCE_DIR}/Tools/setup/requirements.txt
+	USES_TERMINAL
+)

+#include <openssl/pem.h>
+#include <openssl/evp.h>
+#include <openssl/bio.h>
+#include <openssl/err.h>
+#include <iostream>
+#include <iomanip>
+#include <fstream>
+#include <cstring>
+#include <algorithm>
+
+
+using namespace std;
+
+
+int generate_key()
+{
+	ofstream fout;
+	BIO* bio;
+
+	// generate key pair
+	EVP_PKEY* key = NULL;
+	EVP_PKEY_CTX *pctx = EVP_PKEY_CTX_new_id(EVP_PKEY_ED25519, NULL);
+	if(EVP_PKEY_keygen_init(pctx) != 1)
+	{
+		cout << "Error: EVP_PKEY_keygen_init" << endl;
+		cout << ERR_error_string(ERR_get_error(),NULL) << endl;
+		return 0;
+	}
+	if(EVP_PKEY_keygen(pctx, &key) != 1)
+	{
+		cout << "Error: EVP_PKEY_keygen" << endl;
+		cout << ERR_error_string(ERR_get_error(),NULL) << endl;
+		return 0;
+	}
+	EVP_PKEY_CTX_free(pctx);
+	
+	// save private key
+	bio = BIO_new( BIO_s_mem() );
+	if(PEM_write_bio_PrivateKey(bio, key, NULL, NULL, 0, NULL, NULL) != 1)
+	{
+		cout << "Error: PEM_write_bio_PrivateKey" << endl;
+		cout << ERR_error_string(ERR_get_error(),NULL) << endl;
+		return 0;
+	}
+	unsigned char private_key[120] = { 0 };
+	BIO_read(bio, private_key, 120);
+	BIO_free(bio);
+	cout << private_key << endl;
+	fout.open("private_key");
+	fout << private_key;
+	fout.close();	
+
+	// save public key
+	bio = BIO_new( BIO_s_mem() );
+	if(PEM_write_bio_PUBKEY(bio, key) != 1)
+	{
+		cout << "Error: PEM_write_bio_PUBKEY" << endl;
+		cout << ERR_error_string(ERR_get_error(),NULL) << endl;
+		return 0;
+	}
+	EVP_PKEY_free(key);
+	unsigned char public_key[120] = { 0 };
+	BIO_read(bio, public_key, 120);
+	BIO_free(bio);
+	cout << public_key << endl;
+	fout.open("public_key");
+	fout << public_key;
+	fout.close();
+
+	return 1;
+}
+
+
+
+int sign(char* signee_file, char* key_file)
+{
+	ifstream fin;
+	ofstream fout;	
+	BIO* bio;
+	EVP_PKEY* pkey = NULL;
+	int signee_size = 0, key_size = 0;
+	
+	// open signee_file
+	fin.open(signee_file);
+	if (fin.fail()) {
+		cout << "Error: Can't open signee file." << endl;
+		return 0;
+	}
+	fin.seekg(0, ios::end);
+	signee_size = fin.tellg();
+	fin.seekg(0, ios::beg);
+	unsigned char* signee = new unsigned char[signee_size];
+	fin.read((char*)signee, signee_size);
+	fin.close();
+
+	// open private key
+	fin.open(key_file);
+	if (fin.fail()) {
+		cout << "Error: Can't open key file." << endl;
+		return 0;
+	}
+	fin.seekg(0, ios::end);
+	key_size = fin.tellg();
+	fin.seekg(0, ios::beg);
+	unsigned char* key = new unsigned char[key_size];
+	fin.read((char*)key, key_size);
+	fin.close();
+	cout << key << endl;
+	bio = BIO_new( BIO_s_mem() );
+	BIO_write(bio, key, key_size);
+	if(PEM_read_bio_PrivateKey(bio, &pkey, NULL, NULL) == NULL)
+	{	
+		cout << "Error: PEM_read_bio_PrivateKey" << endl;
+		cout << ERR_error_string(ERR_get_error(),NULL) << endl;
+		return 0;
+	}
+	BIO_free(bio);
+
+	// File Signing, Make Signature
+	unsigned char sig[65] = { 0 };
+	size_t sig_size = 64;
+	EVP_MD_CTX* ctx = EVP_MD_CTX_new();
+	if(EVP_DigestSignInit(ctx, NULL, NULL, NULL, pkey) != 1)
+	{
+		cout << "Error: EVP_DigestSignInit" << endl;
+		cout << ERR_error_string(ERR_get_error(),NULL) << endl;
+		return 0;
+	}
+	if(EVP_DigestSign(ctx, sig, &sig_size, signee, signee_size) != 1)
+	{
+		cout << "Error: EVP_DigestSign" << endl;
+		cout << ERR_error_string(ERR_get_error(),NULL) << endl;
+		return 0;
+	}
+	EVP_MD_CTX_free(ctx);
+	EVP_PKEY_free(pkey);
+
+	fout.open("./signature");
+	cout << hex << setfill('0');
+	fout << hex << setfill('0');
+	for(int i = 0; i < sig_size; i++)
+	{
+		cout << setw(2) << (int)sig[i];
+		fout << setw(2) << (int)sig[i];
+	}
+	cout << endl;
+	fout.close();
+
+	return 1;
+}
+
+
+/*
+int verify(char* signee_file, char* sig_file, char* key_file)
+{
+	ifstream fin;
+	BIO* bio;
+	EVP_PKEY* pkey = NULL;
+	int signee_size = 0, key_size = 0, sig_size = 0;
+	
+	// open signee_file
+	fin.open(signee_file);
+	fin.seekg(0, ios::end);
+	signee_size = fin.tellg();
+	fin.seekg(0, ios::beg);
+	unsigned char* signee = new unsigned char[signee_size];
+	fin.read((char*)signee, signee_size);
+	fin.close();
+
+	// open public key
+	fin.open(key_file);
+	fin.seekg(0, ios::end);
+	key_size = fin.tellg();
+	fin.seekg(0, ios::beg);
+	unsigned char* key = new unsigned char[key_size];
+	fin.read((char*)key, key_size);
+	fin.close();
+	cout << key << endl;
+	bio = BIO_new( BIO_s_mem() );
+	BIO_write(bio, key, key_size);
+	if(PEM_read_bio_PUBKEY(bio, &pkey, NULL, NULL) == NULL)
+	{	
+		cout << "Error: " << ERR_error_string(ERR_get_error(),NULL) << endl;
+		return 0;
+	}
+	BIO_free(bio);
+
+	fin.open(sig_file);
+	fin.seekg(0, ios::end);
+	sig_size = fin.tellg();
+	fin.seekg(0, ios::beg);
+	unsigned char* sig_char = new unsigned char[sig_size];
+	fin.read((char*)sig_char, sig_size);
+	fin.close();
+	unsigned char sig[65] = { 0 };
+	char temp[3] = { 0 };
+	for(int i = 0; i < sig_size; i+=2)
+	{
+		temp[0] = sig_char[i];
+		temp[1] = sig_char[i+1];
+		sig[i/2] = (unsigned char) strtol(temp, NULL, 16);
+	}
+	sig_size /= 2;
+
+	EVP_MD_CTX* ctx = EVP_MD_CTX_new();
+	if(EVP_DigestVerifyInit(ctx, NULL, NULL, NULL, pkey) != 1)
+	{
+		cout << "Error: " << ERR_error_string(ERR_get_error(),NULL) << endl;
+		return 0;
+	}
+	if(EVP_DigestVerify(ctx, sig, sig_size, signee, signee_size) != 1)
+	{
+		cout << "Error: " << ERR_error_string(ERR_get_error(),NULL) << endl;
+		return 0;
+	}
+	EVP_PKEY_free(pkey);
+	
+	cout << "Success" << endl;
+	return 1;
+}
+*/
+
+
+bool cmdOptionExists(char** begin, char** end, const string& option)
+{
+	return find(begin, end, option) != end;
+}
+
+
+
+char* getCmdOption(char** begin, char** end, const string& option)
+{
+	char** itr = find(begin, end, option);
+	if (itr != end && ++itr != end)
+		return *itr;
+	return 0;
+}
+
+
+
+int main(int argc, char* argv[])
+{
+	if (cmdOptionExists(argv, argv+argc, "-h")\
+		|| cmdOptionExists(argv, argv+argc, "--help"))
+	{
+		cout << "Usage" << endl;
+		cout << "Generate key: " << argv[0] << " --genkey" << endl;
+		cout << "Signing file: " << argv[0] << " -f signee_path -k key_path" << endl;
+		return 0;
+	}
+
+	if (cmdOptionExists(argv, argv+argc, "--genkey"))
+	{
+		generate_key();
+		return 0;
+	}
+
+	if (cmdOptionExists(argv, argv+argc, "-f")\
+		&& cmdOptionExists(argv, argv+argc, "-k"))
+	{
+		char* signee_path = getCmdOption(argv, argv+argc, "-f");
+		char* key_path = getCmdOption(argv, argv+argc, "-k");
+		if (sign(signee_path, key_path) != 1)
+			cout << "Error occured" << endl;
+		return 0;
+	}
+	else
+	{
+		cout << "Usage" << endl;
+		cout << "Generate key: " << argv[0] << " --genkey" << endl;
+		cout << "Signing file: " << argv[0] << " -f signee_path -k key_path" << endl;
+	}
+//	generate_key();
+//	sign(argv[1], argv[2]);
+//	verify(argv[1], argv[2], argv[3]);
+	return 0;
+}

+/****************************************************************************
+ *
+ *   Copyright (c) 2015 Mark Charlebois. All rights reserved.
+ *   Copyright (c) 2016-2019 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 simulator.cpp
+ *
+ * This module interfaces via MAVLink to a software in the loop simulator (SITL)
+ * such as jMAVSim or Gazebo.
+ */
+
+#include <px4_platform_common/log.h>
+#include <px4_platform_common/tasks.h>
+#include <px4_platform_common/time.h>
+#include <systemlib/err.h>
+#include <drivers/drv_board_led.h>
+#include <openssl/evp.h>
+#include <openssl/pem.h>
+#include <openssl/bio.h>
+#include <openssl/err.h>
+#include <fstream>
+#include <cstring>
+
+#include "simulator.h"
+
+static px4_task_t g_sim_task = -1;
+
+Simulator *Simulator::_instance = nullptr;
+
+void Simulator::parameters_update(bool force)
+{
+	// check for parameter updates
+	if (_parameter_update_sub.updated() || force) {
+		// clear update
+		parameter_update_s pupdate;
+		_parameter_update_sub.copy(&pupdate);
+
+		// update parameters from storage
+		updateParams();
+	}
+}
+
+int Simulator::verify()
+{
+/*
+	char path[256];
+	if(getcwd(path, 256) == NULL)
+		PX4_INFO("Test path: %s", strerror(errno));
+	else
+		PX4_INFO("Test path: %s", path);
+*/
+
+	std::ifstream fin;
+	BIO* bio;
+	EVP_PKEY* pkey = NULL;
+
+	const char* file_path = "../../bin/px4";	
+//	const char* file_path = "../../../../Tools/test.txt";
+	const char* sig_path = "../../../../Tools/signature";	
+	const char* key_path = "../../../../Tools/public_key";
+
+	int file_size = 0, sig_size = 0, key_size = 0;
+
+	// open exe file
+	fin.open(file_path);
+	if (fin.fail()) {
+		PX4_WARN("Error: Can't open exe file during signature verifying.");
+		return 0;
+	}
+	fin.seekg(0, std::ios::end);
+	file_size = fin.tellg();
+	fin.seekg(0, std::ios::beg);
+	unsigned char* file = new unsigned char[file_size];
+	fin.read((char*)file, file_size);
+	fin.close();
+
+	// open signature file
+	fin.open(sig_path);
+	if (fin.fail()) {
+		PX4_WARN("Error: Can't open signature file during signature verifying.");
+		return 0;
+	}
+	fin.seekg(0, std::ios::end);
+	sig_size = fin.tellg();
+	fin.seekg(0, std::ios::beg);
+	unsigned char* sig_char = new unsigned char[sig_size];
+	fin.read((char*)sig_char, sig_size);
+	fin.close();
+	unsigned char sig[65] = { 0 };
+	char temp[3] = { 0 };
+	for (int i = 0; i < sig_size; i+=2)
+	{
+		temp[0] = sig_char[i];
+		temp[1] = sig_char[i+1];
+		sig[i/2] = (unsigned char)strtol(temp, NULL, 16);
+	}
+	delete[] sig_char;
+	sig_size /= 2;
+
+	// open public key file
+	fin.open(key_path);
+	if (fin.fail()) {
+		PX4_WARN("Error: Can't open public key file during signature verifying.");
+		return 0;
+	}
+	fin.seekg(0, std::ios::end);
+	key_size = fin.tellg();
+	fin.seekg(0, std::ios::beg);
+	unsigned char* key = new unsigned char[key_size];
+	fin.read((char*)key, key_size);
+	fin.close();
+
+	// make key file to pkey
+	bio = BIO_new( BIO_s_mem() );
+	BIO_write(bio, key, key_size);
+	if (PEM_read_bio_PUBKEY(bio, &pkey, NULL, NULL) == NULL) {
+		PX4_WARN("Error: PEM_read_bio_PUBKEY");	//ERR_error_string(ERR_get_error(), NULL)
+		return 0;
+	}
+	delete[] key;
+	BIO_free(bio);
+
+	// verifying signature
+	EVP_MD_CTX* ctx = EVP_MD_CTX_new();
+	if (EVP_DigestVerifyInit(ctx, NULL, NULL, NULL, pkey) != 1) {
+		PX4_WARN("Error: EVP_DigestVerifyInit");	//ERR_error_string(ERR_get_error(), NULL)
+		return 0;
+	}
+	if (EVP_DigestVerify(ctx, sig, sig_size, file, file_size) != 1) {
+		return 0;
+	}
+	EVP_PKEY_free(pkey);	
+	EVP_MD_CTX_free(ctx);
+	delete[] file;
+
+	PX4_INFO("Success: Verifying Signature");
+
+	return 1;
+}
+
+int Simulator::start(int argc, char *argv[])
+{
+
+	_instance = new Simulator();
+
+	if (_instance->verify() != 1) {
+		PX4_ERR("Signature Verifying failed");
+		return 1;
+	}
+
+	if (_instance) {
+
+		if (argc == 5 && strcmp(argv[3], "-u") == 0) {
+			_instance->set_ip(InternetProtocol::UDP);
+			_instance->set_port(atoi(argv[4]));
+		}
+
+		if (argc == 5 && strcmp(argv[3], "-c") == 0) {
+			_instance->set_ip(InternetProtocol::TCP);
+			_instance->set_port(atoi(argv[4]));
+		}
+
+		if (argc == 6 && strcmp(argv[3], "-t") == 0) {
+			PX4_INFO("Simulator using TCP on remote host %s port %s", argv[4], argv[5]);
+			PX4_WARN("Please ensure port %s is not blocked by a firewall.", argv[5]);
+			_instance->set_ip(InternetProtocol::TCP);
+			_instance->set_tcp_remote_ipaddr(argv[4]);
+			_instance->set_port(atoi(argv[5]));
+		}
+
+		if (argc == 6 && strcmp(argv[3], "-h") == 0) {
+			PX4_INFO("Simulator using TCP on remote host %s port %s", argv[4], argv[5]);
+			PX4_WARN("Please ensure port %s is not blocked by a firewall.", argv[5]);
+			_instance->set_ip(InternetProtocol::TCP);
+			_instance->set_hostname(argv[4]);
+			_instance->set_port(atoi(argv[5]));
+		}
+
+		_instance->run();
+
+		return 0;
+
+	} else {
+		PX4_WARN("Simulator creation failed");
+		return 1;
+	}
+}
+
+static void usage()
+{
+	PX4_INFO("Usage: simulator {start -[spt] [-u udp_port / -c tcp_port] |stop|status}");
+	PX4_INFO("Start simulator:     simulator start");
+	PX4_INFO("Connect using UDP: simulator start -u udp_port");
+	PX4_INFO("Connect using TCP: simulator start -c tcp_port");
+	PX4_INFO("Connect to a remote server using TCP: simulator start -t ip_addr tcp_port");
+	PX4_INFO("Connect to a remote server via hostname using TCP: simulator start -h hostname tcp_port");
+}
+
+__BEGIN_DECLS
+extern int simulator_main(int argc, char *argv[]);
+__END_DECLS
+
+
+int simulator_main(int argc, char *argv[])
+{
+	if (argc > 1 && strcmp(argv[1], "start") == 0) {
+
+		if (g_sim_task >= 0) {
+			PX4_WARN("Simulator already started");
+			return 0;
+		}
+
+		g_sim_task = px4_task_spawn_cmd("simulator",
+						SCHED_DEFAULT,
+						SCHED_PRIORITY_MAX,
+						1500,
+						Simulator::start,
+						argv);
+
+#if defined(ENABLE_LOCKSTEP_SCHEDULER)
+
+		// We want to prevent the rest of the startup script from running until time
+		// is initialized by the HIL_SENSOR messages from the simulator.
+		while (true) {
+			if (Simulator::getInstance() && Simulator::getInstance()->has_initialized()) {
+				break;
+			}
+
+			system_usleep(100);
+		}
+
+#endif
+
+	} else if (argc == 2 && strcmp(argv[1], "stop") == 0) {
+		if (g_sim_task < 0) {
+			PX4_WARN("Simulator not running");
+			return 1;
+
+		} else {
+			px4_task_delete(g_sim_task);
+			g_sim_task = -1;
+		}
+
+	} else if (argc == 2 && strcmp(argv[1], "status") == 0) {
+		if (g_sim_task < 0) {
+			PX4_WARN("Simulator not running");
+			return 1;
+
+		} else {
+			PX4_INFO("running");
+		}
+
+	} else {
+		usage();
+		return 1;
+	}
+
+	return 0;
+}

+/****************************************************************************
+ *
+ *   Copyright (c) 2015 Mark Charlebois. All rights reserved.
+ *   Copyright (c) 2016-2019 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 simulator.h
+ *
+ * This module interfaces via MAVLink to a software in the loop simulator (SITL)
+ * such as jMAVSim or Gazebo.
+ */
+
+#pragma once
+
+#include <drivers/drv_hrt.h>
+#include <drivers/drv_rc_input.h>
+#include <lib/drivers/accelerometer/PX4Accelerometer.hpp>
+#include <lib/drivers/barometer/PX4Barometer.hpp>
+#include <lib/drivers/gyroscope/PX4Gyroscope.hpp>
+#include <lib/drivers/magnetometer/PX4Magnetometer.hpp>
+#include <lib/ecl/geo/geo.h>
+#include <lib/perf/perf_counter.h>
+#include <px4_platform_common/atomic.h>
+#include <px4_platform_common/bitmask.h>
+#include <px4_platform_common/module_params.h>
+#include <px4_platform_common/posix.h>
+#include <uORB/Publication.hpp>
+#include <uORB/Subscription.hpp>
+#include <uORB/SubscriptionInterval.hpp>
+#include <uORB/topics/actuator_outputs.h>
+#include <uORB/topics/differential_pressure.h>
+#include <uORB/topics/distance_sensor.h>
+#include <uORB/topics/irlock_report.h>
+#include <uORB/topics/manual_control_setpoint.h>
+#include <uORB/topics/optical_flow.h>
+#include <uORB/topics/parameter_update.h>
+#include <uORB/topics/sensor_gps.h>
+#include <uORB/topics/vehicle_angular_velocity.h>
+#include <uORB/topics/vehicle_attitude.h>
+#include <uORB/topics/vehicle_global_position.h>
+#include <uORB/topics/vehicle_local_position.h>
+#include <uORB/topics/vehicle_odometry.h>
+#include <uORB/topics/vehicle_status.h>
+#include <uORB/topics/vehicle_command.h>
+#include <uORB/topics/vehicle_command_ack.h>
+
+#include <random>
+
+#include <v2.0/common/mavlink.h>
+#include <v2.0/mavlink_types.h>
+
+using namespace time_literals;
+
+//! Enumeration to use on the bitmask in HIL_SENSOR
+enum class SensorSource {
+	ACCEL		= 0b111,
+	GYRO		= 0b111000,
+	MAG		= 0b111000000,
+	BARO		= 0b1101000000000,
+	DIFF_PRESS	= 0b10000000000
+};
+ENABLE_BIT_OPERATORS(SensorSource)
+
+//! AND operation for the enumeration and unsigned types that returns the bitmask
+template<typename A, typename B>
+static inline SensorSource operator &(A lhs, B rhs)
+{
+	// make it type safe
+	static_assert((std::is_same<A, uint32_t>::value || std::is_same<A, SensorSource>::value),
+		      "first argument is not uint32_t or SensorSource enum type");
+	static_assert((std::is_same<B, uint32_t>::value || std::is_same<B, SensorSource>::value),
+		      "second argument is not uint32_t or SensorSource enum type");
+
+	typedef typename std::underlying_type<SensorSource>::type underlying;
+
+	return static_cast<SensorSource>(
+		       static_cast<underlying>(lhs) &
+		       static_cast<underlying>(rhs)
+	       );
+}
+
+class Simulator : public ModuleParams
+{
+public:
+	static Simulator *getInstance() { return _instance; }
+
+	enum class InternetProtocol {
+		TCP,
+		UDP
+	};
+
+	static int start(int argc, char *argv[]);
+
+	void set_ip(InternetProtocol ip) { _ip = ip; }
+	void set_port(unsigned port) { _port = port; }
+	void set_hostname(std::string hostname) { _hostname = hostname; }
+	void set_tcp_remote_ipaddr(char *tcp_remote_ipaddr) { _tcp_remote_ipaddr = tcp_remote_ipaddr; }
+
+#if defined(ENABLE_LOCKSTEP_SCHEDULER)
+	bool has_initialized() { return _has_initialized.load(); }
+#endif
+
+private:
+	Simulator() : ModuleParams(nullptr)
+	{
+	}
+
+	~Simulator()
+	{
+		// free perf counters
+		perf_free(_perf_sim_delay);
+		perf_free(_perf_sim_interval);
+
+		for (size_t i = 0; i < sizeof(_dist_pubs) / sizeof(_dist_pubs[0]); i++) {
+			delete _dist_pubs[i];
+		}
+
+		px4_lockstep_unregister_component(_lockstep_component);
+
+		for (size_t i = 0; i < sizeof(_sensor_gps_pubs) / sizeof(_sensor_gps_pubs[0]); i++) {
+			delete _sensor_gps_pubs[i];
+		}
+
+		_instance = nullptr;
+	}
+
+
+	void check_failure_injections();
+
+	int publish_flow_topic(const mavlink_hil_optical_flow_t *flow);
+	int publish_odometry_topic(const mavlink_message_t *odom_mavlink);
+	int publish_distance_topic(const mavlink_distance_sensor_t *dist);
+
+	static Simulator *_instance;
+
+	// simulated sensor instances
+	static constexpr uint8_t ACCEL_COUNT_MAX = 3;
+	PX4Accelerometer _px4_accel[ACCEL_COUNT_MAX] {
+		{1310988, ROTATION_NONE}, // 1310988: DRV_IMU_DEVTYPE_SIM, BUS: 1, ADDR: 1, TYPE: SIMULATION
+		{1310996, ROTATION_NONE}, // 1310996: DRV_IMU_DEVTYPE_SIM, BUS: 2, ADDR: 1, TYPE: SIMULATION
+		{1311004, ROTATION_NONE}, // 1311004: DRV_IMU_DEVTYPE_SIM, BUS: 3, ADDR: 1, TYPE: SIMULATION
+	};
+
+	static constexpr uint8_t GYRO_COUNT_MAX = 3;
+	PX4Gyroscope _px4_gyro[GYRO_COUNT_MAX] {
+		{1310988, ROTATION_NONE}, // 1310988: DRV_IMU_DEVTYPE_SIM, BUS: 1, ADDR: 1, TYPE: SIMULATION
+		{1310996, ROTATION_NONE}, // 1310996: DRV_IMU_DEVTYPE_SIM, BUS: 2, ADDR: 1, TYPE: SIMULATION
+		{1311004, ROTATION_NONE}, // 1311004: DRV_IMU_DEVTYPE_SIM, BUS: 3, ADDR: 1, TYPE: SIMULATION
+	};
+
+	PX4Magnetometer		_px4_mag_0{197388, ROTATION_NONE}; // 197388: DRV_MAG_DEVTYPE_MAGSIM, BUS: 1, ADDR: 1, TYPE: SIMULATION
+	PX4Magnetometer		_px4_mag_1{197644, ROTATION_NONE}; // 197644: DRV_MAG_DEVTYPE_MAGSIM, BUS: 2, ADDR: 1, TYPE: SIMULATION
+
+	PX4Barometer		_px4_baro_0{6620172}; // 6620172: DRV_BARO_DEVTYPE_BAROSIM, BUS: 1, ADDR: 4, TYPE: SIMULATION
+	PX4Barometer		_px4_baro_1{6620428}; // 6620428: DRV_BARO_DEVTYPE_BAROSIM, BUS: 2, ADDR: 4, TYPE: SIMULATION
+
+	float _sensors_temperature{0};
+
+	perf_counter_t _perf_sim_delay{perf_alloc(PC_ELAPSED, MODULE_NAME": network delay")};
+	perf_counter_t _perf_sim_interval{perf_alloc(PC_INTERVAL, MODULE_NAME": network interval")};
+
+	// uORB publisher handlers
+	uORB::Publication<differential_pressure_s>	_differential_pressure_pub{ORB_ID(differential_pressure)};
+	uORB::PublicationMulti<optical_flow_s>		_flow_pub{ORB_ID(optical_flow)};
+	uORB::Publication<irlock_report_s>		_irlock_report_pub{ORB_ID(irlock_report)};
+	uORB::Publication<vehicle_odometry_s>		_visual_odometry_pub{ORB_ID(vehicle_visual_odometry)};
+	uORB::Publication<vehicle_odometry_s>		_mocap_odometry_pub{ORB_ID(vehicle_mocap_odometry)};
+
+	uORB::Publication<vehicle_command_ack_s>	_command_ack_pub{ORB_ID(vehicle_command_ack)};
+
+	uORB::PublicationMulti<distance_sensor_s>	*_dist_pubs[ORB_MULTI_MAX_INSTANCES] {};
+	uint32_t _dist_sensor_ids[ORB_MULTI_MAX_INSTANCES] {};
+
+	uORB::SubscriptionInterval _parameter_update_sub{ORB_ID(parameter_update), 1_s};
+
+	unsigned int _port{14560};
+
+	InternetProtocol _ip{InternetProtocol::UDP};
+
+	std::string _hostname{""};
+
+	char *_tcp_remote_ipaddr{nullptr};
+
+	double _realtime_factor{1.0};		///< How fast the simulation runs in comparison to real system time
+
+	hrt_abstime _last_sim_timestamp{0};
+	hrt_abstime _last_sitl_timestamp{0};
+
+	int verify();
+
+	void run();
+	void handle_message(const mavlink_message_t *msg);
+	void handle_message_distance_sensor(const mavlink_message_t *msg);
+	void handle_message_hil_gps(const mavlink_message_t *msg);
+	void handle_message_hil_sensor(const mavlink_message_t *msg);
+	void handle_message_hil_state_quaternion(const mavlink_message_t *msg);
+	void handle_message_landing_target(const mavlink_message_t *msg);
+	void handle_message_odometry(const mavlink_message_t *msg);
+	void handle_message_optical_flow(const mavlink_message_t *msg);
+	void handle_message_rc_channels(const mavlink_message_t *msg);
+	void handle_message_vision_position_estimate(const mavlink_message_t *msg);
+
+	void parameters_update(bool force);
+	void poll_for_MAVLink_messages();
+	void request_hil_state_quaternion();
+	void send();
+	void send_controls();
+	void send_heartbeat();
+	void send_mavlink_message(const mavlink_message_t &aMsg);
+	void update_sensors(const hrt_abstime &time, const mavlink_hil_sensor_t &sensors);
+
+	static void *sending_trampoline(void *);
+
+	void actuator_controls_from_outputs(mavlink_hil_actuator_controls_t *msg);
+
+
+	// uORB publisher handlers
+	uORB::Publication<vehicle_angular_velocity_s>	_vehicle_angular_velocity_ground_truth_pub{ORB_ID(vehicle_angular_velocity_groundtruth)};
+	uORB::Publication<vehicle_attitude_s>		_attitude_ground_truth_pub{ORB_ID(vehicle_attitude_groundtruth)};
+	uORB::Publication<vehicle_global_position_s>	_gpos_ground_truth_pub{ORB_ID(vehicle_global_position_groundtruth)};
+	uORB::Publication<vehicle_local_position_s>	_lpos_ground_truth_pub{ORB_ID(vehicle_local_position_groundtruth)};
+	uORB::Publication<input_rc_s>			_input_rc_pub{ORB_ID(input_rc)};
+
+	// HIL GPS
+	static constexpr int MAX_GPS = 3;
+	uORB::PublicationMulti<sensor_gps_s>	*_sensor_gps_pubs[MAX_GPS] {};
+	uint8_t _gps_ids[MAX_GPS] {};
+	std::default_random_engine _gen{};
+
+	// uORB subscription handlers
+	int _actuator_outputs_sub{-1};
+	actuator_outputs_s _actuator_outputs{};
+
+	uORB::Subscription _vehicle_status_sub{ORB_ID(vehicle_status)};
+	uORB::Subscription _vehicle_command_sub{ORB_ID(vehicle_command)};
+
+	// hil map_ref data
+	map_projection_reference_s	_global_local_proj_ref{};
+	float						_global_local_alt0{NAN};
+
+	vehicle_status_s _vehicle_status{};
+
+	bool _accel_blocked[ACCEL_COUNT_MAX] {};
+	bool _accel_stuck[ACCEL_COUNT_MAX] {};
+	sensor_accel_fifo_s _last_accel_fifo{};
+	matrix::Vector3f _last_accel[GYRO_COUNT_MAX] {};
+
+	bool _gyro_blocked[GYRO_COUNT_MAX] {};
+	bool _gyro_stuck[GYRO_COUNT_MAX] {};
+	sensor_gyro_fifo_s _last_gyro_fifo{};
+	matrix::Vector3f _last_gyro[GYRO_COUNT_MAX] {};
+
+	bool _baro_blocked{false};
+	bool _baro_stuck{false};
+
+	bool _mag_blocked{false};
+	bool _mag_stuck{false};
+
+	bool _gps_blocked{false};
+	bool _airspeed_blocked{false};
+
+	float _last_magx{0.0f};
+	float _last_magy{0.0f};
+	float _last_magz{0.0f};
+
+#if defined(ENABLE_LOCKSTEP_SCHEDULER)
+	px4::atomic<bool> _has_initialized {false};
+#endif
+
+	int _lockstep_component{-1};
+
+	DEFINE_PARAMETERS(
+		(ParamInt<px4::params::MAV_TYPE>) _param_mav_type,
+		(ParamInt<px4::params::MAV_SYS_ID>) _param_mav_sys_id,
+		(ParamInt<px4::params::MAV_COMP_ID>) _param_mav_comp_id
+	)
+};

+############################################################################
+#
+# Copyright (c) 2017 - 2019 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.
+#
+############################################################################
+
+#=============================================================================
+# CMAKE CODING STANDARD FOR PX4
+#
+# Structure
+# ---------------------------------------------------------------------------
+#
+# * Common functions should be included in px_base.cmake.
+#
+# * OS/ board specific fucntions should be include in
+#	px_impl_${PX4_PLATFORM}.cmake or px4_impl_${PX4_PLATFORM}_${PX4_BOARD}.cmake.
+#
+# Formatting
+# ---------------------------------------------------------------------------
+#
+# * Use hard indents to match the px4 source code.
+#
+# * All function and script arguments are upper case.
+#
+# * All local variables are lower case.
+#
+# * All cmake functions are lowercase.
+#
+# * For else, endif, endfunction, etc, never put the name of the statement
+#
+# Functions/Macros
+# ---------------------------------------------------------------------------
+#
+# * Use px4_parse_function_args to parse functions and check for required
+#   arguments. Unless there is only one argument in the function and it is clear.
+#
+# * Never use macros. They allow overwriting global variables and this
+#	makes variable declarations hard to locate.
+#
+# * If a target from add_custom_* is set in a function, explicitly pass it
+#	as an output argument so that the target name is clear to the user.
+#
+# * Avoid use of global variables in functions. Functions in a nested
+#	scope may use global variables, but this makes it difficult to
+#	reuse functions.
+#
+# Included CMake Files
+# ---------------------------------------------------------------------------
+#
+# * All variables in config files must have the prefix "config_".
+#
+# * Never set global variables in an included cmake file,
+#	you may only define functions. This excludes config and Toolchain files.
+#	This makes it clear to the user when variables are being set or targets
+#	are being created.
+#
+# * Setting a global variable in a CMakeLists.txt file is ok, because
+#	each CMakeLists.txt file has scope in the current directory and all
+#	subdirectories, so it is not truly global.
+#
+# * All toolchain files should be included in the cmake
+#	directory and named Toolchain-"name".cmake.
+#
+# Misc
+# ---------------------------------------------------------------------------
+#
+# * If referencing a string variable, don't put it in quotes.
+#	Don't do "${PX4_PLATFORM}" STREQUAL "posix",
+#	instead type ${PX4_PLATFORM} STREQUAL "posix". This will throw an
+#	error when ${PX4_PLATFORM} is not defined instead of silently
+#	evaluating to false.
+#
+#=============================================================================
+
+cmake_minimum_required(VERSION 3.2 FATAL_ERROR)
+
+set(PX4_SOURCE_DIR "${CMAKE_CURRENT_SOURCE_DIR}")
+set(PX4_BINARY_DIR "${CMAKE_CURRENT_BINARY_DIR}")
+
+list(APPEND CMAKE_MODULE_PATH ${PX4_SOURCE_DIR}/cmake)
+include(px4_parse_function_args)
+
+#=============================================================================
+# git
+#
+include(px4_git)
+
+execute_process(
+	COMMAND git describe --always --tags
+	OUTPUT_VARIABLE PX4_GIT_TAG
+	OUTPUT_STRIP_TRAILING_WHITESPACE
+	WORKING_DIRECTORY ${PX4_SOURCE_DIR}
+	)
+message(STATUS "PX4 version: ${PX4_GIT_TAG}")
+
+define_property(GLOBAL PROPERTY PX4_MODULE_LIBRARIES
+                 BRIEF_DOCS "PX4 module libs"
+                 FULL_DOCS "List of all PX4 module libraries"
+                 )
+
+define_property(GLOBAL PROPERTY PX4_MODULE_PATHS
+                 BRIEF_DOCS "PX4 module paths"
+                 FULL_DOCS "List of paths to all PX4 modules"
+                 )
+
+#=============================================================================
+# configuration
+#
+
+set(CONFIG "px4_sitl_default" CACHE STRING "desired configuration")
+
+include(px4_add_module)
+set(config_module_list)
+
+include(px4_config)
+include(px4_add_board)
+include(${PX4_CONFIG_FILE})
+message(STATUS "PX4 config: ${PX4_CONFIG}")
+message(STATUS "PX4 platform: ${PX4_PLATFORM}")
+
+if(${PX4_PLATFORM} STREQUAL "posix")
+	if(ENABLE_LOCKSTEP_SCHEDULER)
+		add_definitions(-DENABLE_LOCKSTEP_SCHEDULER)
+		message(STATUS "PX4 lockstep: enabled")
+	else()
+		message(STATUS "PX4 lockstep: disabled")
+	endif()
+endif()
+
+# external modules
+set(EXTERNAL_MODULES_LOCATION "" CACHE STRING "External modules source location")
+
+if(NOT EXTERNAL_MODULES_LOCATION STREQUAL "")
+	get_filename_component(EXTERNAL_MODULES_LOCATION "${EXTERNAL_MODULES_LOCATION}" ABSOLUTE)
+endif()
+
+set_property(GLOBAL PROPERTY PX4_MODULE_CONFIG_FILES)
+
+include(platforms/${PX4_PLATFORM}/cmake/px4_impl_os.cmake)
+list(APPEND CMAKE_MODULE_PATH ${PX4_SOURCE_DIR}/platforms/${PX4_PLATFORM}/cmake)
+
+if(EXISTS "${PX4_SOURCE_DIR}/platforms/${PX4_PLATFORM}/cmake/init.cmake")
+	include(init)
+endif()
+
+# CMake build type (Debug Release RelWithDebInfo MinSizeRel Coverage)
+if(NOT CMAKE_BUILD_TYPE)
+	if(${PX4_PLATFORM} STREQUAL "nuttx")
+		set(PX4_BUILD_TYPE "MinSizeRel")
+	else()
+		set(PX4_BUILD_TYPE "RelWithDebInfo")
+	endif()
+
+	set(CMAKE_BUILD_TYPE ${PX4_BUILD_TYPE} CACHE STRING "Build type" FORCE)
+endif()
+
+if((CMAKE_BUILD_TYPE STREQUAL "Debug") OR (CMAKE_BUILD_TYPE STREQUAL "Coverage"))
+	set(MAX_CUSTOM_OPT_LEVEL -O0)
+elseif(CMAKE_BUILD_TYPE MATCHES "Sanitizer")
+	set(MAX_CUSTOM_OPT_LEVEL -O1)
+else()
+	if(px4_constrained_flash_build)
+		set(MAX_CUSTOM_OPT_LEVEL -Os)
+	else()
+		set(MAX_CUSTOM_OPT_LEVEL -O2)
+	endif()
+endif()
+
+set_property(CACHE CMAKE_BUILD_TYPE PROPERTY STRINGS "Debug;Release;RelWithDebInfo;MinSizeRel;Coverage;AddressSanitizer;UndefinedBehaviorSanitizer")
+message(STATUS "cmake build type: ${CMAKE_BUILD_TYPE}")
+
+#=============================================================================
+# project definition
+#
+project(px4 CXX C ASM)
+
+set(package-contact "px4users@googlegroups.com")
+
+set(CMAKE_CXX_STANDARD 14)
+set(CMAKE_CXX_STANDARD_REQUIRED ON)
+set(CMAKE_C_STANDARD 11)
+set(CMAKE_C_STANDARD_REQUIRED ON)
+set(CMAKE_EXPORT_COMPILE_COMMANDS ON)
+
+# For the catkin build process, unset build of dynamically-linked binaries
+# and do not change CMAKE_RUNTIME_OUTPUT_DIRECTORY
+if (NOT CATKIN_DEVEL_PREFIX)
+	set(CMAKE_RUNTIME_OUTPUT_DIRECTORY ${PX4_BINARY_DIR})
+	set(CMAKE_RUNTIME_OUTPUT_DIRECTORY_DEBUG ${PX4_BINARY_DIR})
+	set(CMAKE_RUNTIME_OUTPUT_DIRECTORY_RELEASE ${PX4_BINARY_DIR})
+else()
+	SET(BUILD_SHARED_LIBS OFF)
+endif()
+
+#=============================================================================
+
+# gold linker - use if available (posix only for now)
+if(${PX4_PLATFORM} STREQUAL "posix")
+	include(CMakeDependentOption)
+	CMAKE_DEPENDENT_OPTION(USE_LD_GOLD
+			"Use GNU gold linker" ON
+			"NOT WIN32;NOT APPLE" OFF
+	)
+
+	if(USE_LD_GOLD)
+		execute_process(COMMAND ${CMAKE_C_COMPILER} -fuse-ld=gold -Wl,--version ERROR_QUIET OUTPUT_VARIABLE LD_VERSION)
+		if("${LD_VERSION}" MATCHES "GNU gold")
+			set(CMAKE_EXE_LINKER_FLAGS "${CMAKE_EXE_LINKER_FLAGS} -fuse-ld=gold")
+			set(CMAKE_SHARED_LINKER_FLAGS "${CMAKE_SHARED_LINKER_FLAGS} -fuse-ld=gold")
+		else()
+			set(USE_LD_GOLD OFF)
+		endif()
+	endif()
+endif()
+
+#=============================================================================
+
+# Setup install paths
+if(${PX4_PLATFORM} STREQUAL "posix")
+	# This makes it possible to dynamically load code which depends on symbols
+	# inside the px4 executable.
+	set(CMAKE_POSITION_INDEPENDENT_CODE ON)
+	set(CMAKE_ENABLE_EXPORTS ON)
+
+	include(coverage)
+	include(sanitizers)
+
+	# Define GNU standard installation directories
+	include(GNUInstallDirs)
+
+	if (NOT CMAKE_INSTALL_PREFIX)
+		set(CMAKE_INSTALL_PREFIX "/usr" CACHE PATH "Install path prefix" FORCE)
+	endif()
+endif()
+
+include(ccache)
+
+#=============================================================================
+# find programs and packages
+#
+
+# see if catkin was invoked to build this
+if (CATKIN_DEVEL_PREFIX)
+	message(STATUS "catkin ENABLED")
+	find_package(catkin REQUIRED)
+	if (catkin_FOUND)
+		catkin_package()
+	else()
+		message(FATAL_ERROR "catkin not found")
+	endif()
+endif()
+
+# Python
+# If using catkin, Python 2 is found since it points
+# to the Python libs installed with the ROS distro
+if (NOT CATKIN_DEVEL_PREFIX)
+	find_package(PythonInterp 3)
+	# We have a custom error message to tell users how to install python3.
+	if (NOT PYTHONINTERP_FOUND)
+		message(FATAL_ERROR "Python 3 not found. Please install Python 3:\n"
+			"    Ubuntu: sudo apt install python3 python3-dev python3-pip\n"
+			"    macOS: brew install python")
+	endif()
+else()
+	find_package(PythonInterp REQUIRED)
+endif()
+
+option(PYTHON_COVERAGE "Python code coverage" OFF)
+if(PYTHON_COVERAGE)
+	message(STATUS "python coverage enabled")
+	set(PYTHON_EXECUTABLE coverage run -p)
+endif()
+
+#=============================================================================
+# get chip and chip manufacturer
+#
+px4_os_determine_build_chip()
+if(NOT PX4_CHIP_MANUFACTURER)
+	message(FATAL_ERROR "px4_os_determine_build_chip() needs to set PX4_CHIP_MANUFACTURER")
+endif()
+if(NOT PX4_CHIP)
+	message(FATAL_ERROR "px4_os_determine_build_chip() needs to set PX4_CHIP")
+endif()
+
+#=============================================================================
+# build flags
+#
+include(px4_add_common_flags)
+px4_add_common_flags()
+px4_os_add_flags()
+
+#=============================================================================
+# board cmake init (optional)
+#
+if(EXISTS ${PX4_BOARD_DIR}/cmake/init.cmake)
+	include(${PX4_BOARD_DIR}/cmake/init.cmake)
+endif()
+
+#=============================================================================
+# message, and airframe generation
+#
+include(px4_metadata)
+
+add_subdirectory(msg EXCLUDE_FROM_ALL)
+
+px4_generate_airframes_xml(BOARD ${PX4_BOARD})
+
+#=============================================================================
+# external projects
+#
+set(ep_base ${PX4_BINARY_DIR}/external)
+set_property(DIRECTORY PROPERTY EP_BASE ${ep_base})
+
+# add external project install folders to build
+# add the directories so cmake won't warn
+execute_process(COMMAND ${CMAKE_COMMAND} -E make_directory ${ep_base})
+execute_process(COMMAND ${CMAKE_COMMAND} -E make_directory ${ep_base}/Install)
+execute_process(COMMAND ${CMAKE_COMMAND} -E make_directory ${ep_base}/Install/lib)
+link_directories(${ep_base}/Install/lib)
+execute_process(COMMAND ${CMAKE_COMMAND} -E make_directory ${ep_base}/Install/include)
+include_directories(${ep_base}/Install/include)
+
+#=============================================================================
+# external modules
+#
+set(external_module_paths)
+if (NOT EXTERNAL_MODULES_LOCATION STREQUAL "")
+	message(STATUS "External modules: ${EXTERNAL_MODULES_LOCATION}")
+	add_subdirectory("${EXTERNAL_MODULES_LOCATION}/src" external_modules)
+
+	foreach(external_module ${config_module_list_external})
+		add_subdirectory(${EXTERNAL_MODULES_LOCATION}/src/${external_module} external_modules/${external_module})
+		list(APPEND external_module_paths ${EXTERNAL_MODULES_LOCATION}/src/${external_module})
+	endforeach()
+endif()
+
+#=============================================================================
+# Testing - Automatic unit and integration testing with CTest
+#
+
+# optionally enable cmake testing (supported only on posix)
+option(CMAKE_TESTING "Configure test targets" OFF)
+if(${PX4_CONFIG} STREQUAL "px4_sitl_test")
+	set(CMAKE_TESTING ON)
+endif()
+if(CMAKE_TESTING)
+	include(CTest) # sets BUILD_TESTING variable
+endif()
+
+# enable test filtering to run only specific tests with the ctest -R regex functionality
+set(TESTFILTER "" CACHE STRING "Filter string for ctest to selectively only run specific tests (ctest -R)")
+
+# if testing is enabled download and configure gtest
+list(APPEND CMAKE_MODULE_PATH ${PX4_SOURCE_DIR}/cmake/gtest/)
+include(px4_add_gtest)
+if(BUILD_TESTING)
+	include(gtest)
+
+	add_custom_target(test_results
+			COMMAND GTEST_COLOR=1 ${CMAKE_CTEST_COMMAND} --output-on-failure -T Test -R ${TESTFILTER} USES_TERMINAL
+			DEPENDS
+				px4
+				examples__dyn_hello
+				test_mixer_multirotor
+			USES_TERMINAL
+			COMMENT "Running tests"
+			WORKING_DIRECTORY ${PX4_BINARY_DIR})
+	set_target_properties(test_results PROPERTIES EXCLUDE_FROM_ALL TRUE)
+endif()
+
+
+#=============================================================================
+# subdirectories
+#
+add_library(parameters_interface INTERFACE)
+
+include(px4_add_library)
+add_subdirectory(src/lib EXCLUDE_FROM_ALL)
+
+add_subdirectory(platforms/${PX4_PLATFORM}/src/px4)
+add_subdirectory(platforms EXCLUDE_FROM_ALL)
+
+if(EXISTS "${PX4_BOARD_DIR}/CMakeLists.txt")
+	add_subdirectory(${PX4_BOARD_DIR})
+endif()
+
+foreach(module ${config_module_list})
+	add_subdirectory(src/${module})
+endforeach()
+
+# must be the last module before firmware
+add_subdirectory(src/lib/parameters EXCLUDE_FROM_ALL)
+target_link_libraries(parameters_interface INTERFACE parameters)
+
+# firmware added last to generate the builtin for included modules
+add_subdirectory(platforms/${PX4_PLATFORM})
+
+#=============================================================================
+# uORB graph generation: add a custom target 'uorb_graph'
+#
+set(uorb_graph_config ${PX4_BOARD})
+
+set(graph_module_list "")
+foreach(module ${config_module_list})
+	set(graph_module_list "${graph_module_list}" "--src-path" "src/${module}")
+endforeach()
+
+add_custom_command(OUTPUT ${uorb_graph_config}
+	COMMAND ${PYTHON_EXECUTABLE} ${PX4_SOURCE_DIR}/Tools/uorb_graph/create.py
+		${graph_module_list}
+		--exclude-path src/examples
+		--file ${PX4_SOURCE_DIR}/Tools/uorb_graph/graph_${uorb_graph_config}
+	WORKING_DIRECTORY ${PX4_SOURCE_DIR}
+	COMMENT "Generating uORB graph"
+)
+add_custom_target(uorb_graph DEPENDS ${uorb_graph_config})
+
+
+include(doxygen)
+include(metadata)
+include(package)
+
+# print size
+add_custom_target(size
+	COMMAND size $<TARGET_FILE:px4>
+	DEPENDS px4
+	WORKING_DIRECTORY ${PX4_BINARY_DIR}
+	USES_TERMINAL
+	)
+
+# install python requirements using configured python
+add_custom_target(install_python_requirements
+	COMMAND ${PYTHON_EXECUTABLE} -m pip install --requirement ${PX4_SOURCE_DIR}/Tools/setup/requirements.txt
+	DEPENDS ${PX4_SOURCE_DIR}/Tools/setup/requirements.txt
+	USES_TERMINAL
+)

+/****************************************************************************
+ *
+ *   Copyright (c) 2015 Mark Charlebois. All rights reserved.
+ *   Copyright (c) 2016-2019 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 simulator.cpp
+ *
+ * This module interfaces via MAVLink to a software in the loop simulator (SITL)
+ * such as jMAVSim or Gazebo.
+ */
+
+#include <px4_platform_common/log.h>
+#include <px4_platform_common/tasks.h>
+#include <px4_platform_common/time.h>
+#include <systemlib/err.h>
+#include <drivers/drv_board_led.h>
+
+#include "simulator.h"
+
+static px4_task_t g_sim_task = -1;
+
+Simulator *Simulator::_instance = nullptr;
+
+void Simulator::parameters_update(bool force)
+{
+	// check for parameter updates
+	if (_parameter_update_sub.updated() || force) {
+		// clear update
+		parameter_update_s pupdate;
+		_parameter_update_sub.copy(&pupdate);
+
+		// update parameters from storage
+		updateParams();
+	}
+}
+
+int Simulator::start(int argc, char *argv[])
+{
+	_instance = new Simulator();
+
+	if (_instance) {
+		if (argc == 5 && strcmp(argv[3], "-u") == 0) {
+			_instance->set_ip(InternetProtocol::UDP);
+			_instance->set_port(atoi(argv[4]));
+		}
+
+		if (argc == 5 && strcmp(argv[3], "-c") == 0) {
+			_instance->set_ip(InternetProtocol::TCP);
+			_instance->set_port(atoi(argv[4]));
+		}
+
+		if (argc == 6 && strcmp(argv[3], "-t") == 0) {
+			_instance->set_ip(InternetProtocol::TCP);
+			_instance->set_tcp_remote_ipaddr(argv[4]);
+			_instance->set_port(atoi(argv[5]));
+		}
+
+		_instance->run();
+
+		return 0;
+
+	} else {
+		PX4_WARN("Simulator creation failed");
+		return 1;
+	}
+}
+
+static void usage()
+{
+	PX4_INFO("Usage: simulator {start -[spt] [-u udp_port / -c tcp_port] |stop|status}");
+	PX4_INFO("Start simulator:     simulator start");
+	PX4_INFO("Connect using UDP: simulator start -u udp_port");
+	PX4_INFO("Connect using TCP: simulator start -c tcp_port");
+	PX4_INFO("Connect to a remote server using TCP: simulator start -t ip_addr tcp_port");
+}
+
+__BEGIN_DECLS
+extern int simulator_main(int argc, char *argv[]);
+__END_DECLS
+
+
+int simulator_main(int argc, char *argv[])
+{
+	if (argc > 1 && strcmp(argv[1], "start") == 0) {
+
+		if (g_sim_task >= 0) {
+			PX4_WARN("Simulator already started");
+			return 0;
+		}
+
+		g_sim_task = px4_task_spawn_cmd("simulator",
+						SCHED_DEFAULT,
+						SCHED_PRIORITY_MAX,
+						1500,
+						Simulator::start,
+						argv);
+
+#if defined(ENABLE_LOCKSTEP_SCHEDULER)
+
+		// We want to prevent the rest of the startup script from running until time
+		// is initialized by the HIL_SENSOR messages from the simulator.
+		while (true) {
+			if (Simulator::getInstance() && Simulator::getInstance()->has_initialized()) {
+				break;
+			}
+
+			system_usleep(100);
+		}
+
+#endif
+
+	} else if (argc == 2 && strcmp(argv[1], "stop") == 0) {
+		if (g_sim_task < 0) {
+			PX4_WARN("Simulator not running");
+			return 1;
+
+		} else {
+			px4_task_delete(g_sim_task);
+			g_sim_task = -1;
+		}
+
+	} else if (argc == 2 && strcmp(argv[1], "status") == 0) {
+		if (g_sim_task < 0) {
+			PX4_WARN("Simulator not running");
+			return 1;
+
+		} else {
+			PX4_INFO("running");
+		}
+
+	} else {
+		usage();
+		return 1;
+	}
+
+	return 0;
+}

+/****************************************************************************
+ *
+ *   Copyright (c) 2015 Mark Charlebois. All rights reserved.
+ *   Copyright (c) 2016-2019 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 simulator.h
+ *
+ * This module interfaces via MAVLink to a software in the loop simulator (SITL)
+ * such as jMAVSim or Gazebo.
+ */
+
+#pragma once
+
+#include <drivers/drv_hrt.h>
+#include <drivers/drv_rc_input.h>
+#include <lib/drivers/accelerometer/PX4Accelerometer.hpp>
+#include <lib/drivers/barometer/PX4Barometer.hpp>
+#include <lib/drivers/gyroscope/PX4Gyroscope.hpp>
+#include <lib/drivers/magnetometer/PX4Magnetometer.hpp>
+#include <lib/ecl/geo/geo.h>
+#include <lib/perf/perf_counter.h>
+#include <px4_platform_common/atomic.h>
+#include <px4_platform_common/bitmask.h>
+#include <px4_platform_common/module_params.h>
+#include <px4_platform_common/posix.h>
+#include <uORB/Publication.hpp>
+#include <uORB/Subscription.hpp>
+#include <uORB/SubscriptionInterval.hpp>
+#include <uORB/topics/actuator_outputs.h>
+#include <uORB/topics/differential_pressure.h>
+#include <uORB/topics/distance_sensor.h>
+#include <uORB/topics/irlock_report.h>
+#include <uORB/topics/manual_control_setpoint.h>
+#include <uORB/topics/optical_flow.h>
+#include <uORB/topics/parameter_update.h>
+#include <uORB/topics/sensor_gps.h>
+#include <uORB/topics/vehicle_angular_velocity.h>
+#include <uORB/topics/vehicle_attitude.h>
+#include <uORB/topics/vehicle_global_position.h>
+#include <uORB/topics/vehicle_local_position.h>
+#include <uORB/topics/vehicle_odometry.h>
+#include <uORB/topics/vehicle_status.h>
+#include <uORB/topics/vehicle_command.h>
+#include <uORB/topics/vehicle_command_ack.h>
+
+#include <random>
+
+#include <v2.0/common/mavlink.h>
+#include <v2.0/mavlink_types.h>
+
+using namespace time_literals;
+
+//! Enumeration to use on the bitmask in HIL_SENSOR
+enum class SensorSource {
+	ACCEL		= 0b111,
+	GYRO		= 0b111000,
+	MAG		= 0b111000000,
+	BARO		= 0b1101000000000,
+	DIFF_PRESS	= 0b10000000000
+};
+ENABLE_BIT_OPERATORS(SensorSource)
+
+//! AND operation for the enumeration and unsigned types that returns the bitmask
+template<typename A, typename B>
+static inline SensorSource operator &(A lhs, B rhs)
+{
+	// make it type safe
+	static_assert((std::is_same<A, uint32_t>::value || std::is_same<A, SensorSource>::value),
+		      "first argument is not uint32_t or SensorSource enum type");
+	static_assert((std::is_same<B, uint32_t>::value || std::is_same<B, SensorSource>::value),
+		      "second argument is not uint32_t or SensorSource enum type");
+
+	typedef typename std::underlying_type<SensorSource>::type underlying;
+
+	return static_cast<SensorSource>(
+		       static_cast<underlying>(lhs) &
+		       static_cast<underlying>(rhs)
+	       );
+}
+
+class Simulator : public ModuleParams
+{
+public:
+	static Simulator *getInstance() { return _instance; }
+
+	enum class InternetProtocol {
+		TCP,
+		UDP
+	};
+
+	static int start(int argc, char *argv[]);
+
+	void set_ip(InternetProtocol ip) { _ip = ip; }
+	void set_port(unsigned port) { _port = port; }
+	void set_tcp_remote_ipaddr(char *tcp_remote_ipaddr) { _tcp_remote_ipaddr = tcp_remote_ipaddr; }
+
+#if defined(ENABLE_LOCKSTEP_SCHEDULER)
+	bool has_initialized() { return _has_initialized.load(); }
+#endif
+
+private:
+	Simulator() : ModuleParams(nullptr)
+	{
+	}
+
+	~Simulator()
+	{
+		// free perf counters
+		perf_free(_perf_sim_delay);
+		perf_free(_perf_sim_interval);
+
+		for (size_t i = 0; i < sizeof(_dist_pubs) / sizeof(_dist_pubs[0]); i++) {
+			delete _dist_pubs[i];
+		}
+
+		px4_lockstep_unregister_component(_lockstep_component);
+
+		for (size_t i = 0; i < sizeof(_sensor_gps_pubs) / sizeof(_sensor_gps_pubs[0]); i++) {
+			delete _sensor_gps_pubs[i];
+		}
+
+		_instance = nullptr;
+	}
+
+
+	void check_failure_injections();
+
+	int publish_flow_topic(const mavlink_hil_optical_flow_t *flow);
+	int publish_odometry_topic(const mavlink_message_t *odom_mavlink);
+	int publish_distance_topic(const mavlink_distance_sensor_t *dist);
+
+	static Simulator *_instance;
+
+	// simulated sensor instances
+	static constexpr uint8_t ACCEL_COUNT_MAX = 3;
+	PX4Accelerometer _px4_accel[ACCEL_COUNT_MAX] {
+		{1310988, ROTATION_NONE}, // 1310988: DRV_IMU_DEVTYPE_SIM, BUS: 1, ADDR: 1, TYPE: SIMULATION
+		{1310996, ROTATION_NONE}, // 1310996: DRV_IMU_DEVTYPE_SIM, BUS: 2, ADDR: 1, TYPE: SIMULATION
+		{1311004, ROTATION_NONE}, // 1311004: DRV_IMU_DEVTYPE_SIM, BUS: 3, ADDR: 1, TYPE: SIMULATION
+	};
+
+	static constexpr uint8_t GYRO_COUNT_MAX = 3;
+	PX4Gyroscope _px4_gyro[GYRO_COUNT_MAX] {
+		{1310988, ROTATION_NONE}, // 1310988: DRV_IMU_DEVTYPE_SIM, BUS: 1, ADDR: 1, TYPE: SIMULATION
+		{1310996, ROTATION_NONE}, // 1310996: DRV_IMU_DEVTYPE_SIM, BUS: 2, ADDR: 1, TYPE: SIMULATION
+		{1311004, ROTATION_NONE}, // 1311004: DRV_IMU_DEVTYPE_SIM, BUS: 3, ADDR: 1, TYPE: SIMULATION
+	};
+
+	PX4Magnetometer		_px4_mag_0{197388, ROTATION_NONE}; // 197388: DRV_MAG_DEVTYPE_MAGSIM, BUS: 1, ADDR: 1, TYPE: SIMULATION
+	PX4Magnetometer		_px4_mag_1{197644, ROTATION_NONE}; // 197644: DRV_MAG_DEVTYPE_MAGSIM, BUS: 2, ADDR: 1, TYPE: SIMULATION
+
+	PX4Barometer		_px4_baro_0{6620172}; // 6620172: DRV_BARO_DEVTYPE_BAROSIM, BUS: 1, ADDR: 4, TYPE: SIMULATION
+	PX4Barometer		_px4_baro_1{6620428}; // 6620428: DRV_BARO_DEVTYPE_BAROSIM, BUS: 2, ADDR: 4, TYPE: SIMULATION
+
+	float _sensors_temperature{0};
+
+	perf_counter_t _perf_sim_delay{perf_alloc(PC_ELAPSED, MODULE_NAME": network delay")};
+	perf_counter_t _perf_sim_interval{perf_alloc(PC_INTERVAL, MODULE_NAME": network interval")};
+
+	// uORB publisher handlers
+	uORB::Publication<differential_pressure_s>	_differential_pressure_pub{ORB_ID(differential_pressure)};
+	uORB::PublicationMulti<optical_flow_s>		_flow_pub{ORB_ID(optical_flow)};
+	uORB::Publication<irlock_report_s>		_irlock_report_pub{ORB_ID(irlock_report)};
+	uORB::Publication<vehicle_odometry_s>		_visual_odometry_pub{ORB_ID(vehicle_visual_odometry)};
+	uORB::Publication<vehicle_odometry_s>		_mocap_odometry_pub{ORB_ID(vehicle_mocap_odometry)};
+
+	uORB::Publication<vehicle_command_ack_s>	_command_ack_pub{ORB_ID(vehicle_command_ack)};
+
+	uORB::PublicationMulti<distance_sensor_s>	*_dist_pubs[ORB_MULTI_MAX_INSTANCES] {};
+	uint32_t _dist_sensor_ids[ORB_MULTI_MAX_INSTANCES] {};
+
+	uORB::SubscriptionInterval _parameter_update_sub{ORB_ID(parameter_update), 1_s};
+
+	unsigned int _port{14560};
+
+	InternetProtocol _ip{InternetProtocol::UDP};
+
+	char *_tcp_remote_ipaddr{nullptr};
+
+	double _realtime_factor{1.0};		///< How fast the simulation runs in comparison to real system time
+
+	hrt_abstime _last_sim_timestamp{0};
+	hrt_abstime _last_sitl_timestamp{0};
+
+
+	void run();
+	void handle_message(const mavlink_message_t *msg);
+	void handle_message_distance_sensor(const mavlink_message_t *msg);
+	void handle_message_hil_gps(const mavlink_message_t *msg);
+	void handle_message_hil_sensor(const mavlink_message_t *msg);
+	void handle_message_hil_state_quaternion(const mavlink_message_t *msg);
+	void handle_message_landing_target(const mavlink_message_t *msg);
+	void handle_message_odometry(const mavlink_message_t *msg);
+	void handle_message_optical_flow(const mavlink_message_t *msg);
+	void handle_message_rc_channels(const mavlink_message_t *msg);
+	void handle_message_vision_position_estimate(const mavlink_message_t *msg);
+
+	void parameters_update(bool force);
+	void poll_for_MAVLink_messages();
+	void request_hil_state_quaternion();
+	void send();
+	void send_controls();
+	void send_heartbeat();
+	void send_mavlink_message(const mavlink_message_t &aMsg);
+	void update_sensors(const hrt_abstime &time, const mavlink_hil_sensor_t &sensors);
+
+	static void *sending_trampoline(void *);
+
+	void actuator_controls_from_outputs(mavlink_hil_actuator_controls_t *msg);
+
+
+	// uORB publisher handlers
+	uORB::Publication<vehicle_angular_velocity_s>	_vehicle_angular_velocity_ground_truth_pub{ORB_ID(vehicle_angular_velocity_groundtruth)};
+	uORB::Publication<vehicle_attitude_s>		_attitude_ground_truth_pub{ORB_ID(vehicle_attitude_groundtruth)};
+	uORB::Publication<vehicle_global_position_s>	_gpos_ground_truth_pub{ORB_ID(vehicle_global_position_groundtruth)};
+	uORB::Publication<vehicle_local_position_s>	_lpos_ground_truth_pub{ORB_ID(vehicle_local_position_groundtruth)};
+	uORB::Publication<input_rc_s>			_input_rc_pub{ORB_ID(input_rc)};
+
+	// HIL GPS
+	static constexpr int MAX_GPS = 3;
+	uORB::PublicationMulti<sensor_gps_s>	*_sensor_gps_pubs[MAX_GPS] {};
+	uint8_t _gps_ids[MAX_GPS] {};
+	std::default_random_engine _gen{};
+
+	// uORB subscription handlers
+	int _actuator_outputs_sub{-1};
+	actuator_outputs_s _actuator_outputs{};
+
+	uORB::Subscription _vehicle_status_sub{ORB_ID(vehicle_status)};
+	uORB::Subscription _vehicle_command_sub{ORB_ID(vehicle_command)};
+
+	// hil map_ref data
+	map_projection_reference_s	_global_local_proj_ref{};
+	float						_global_local_alt0{NAN};
+
+	vehicle_status_s _vehicle_status{};
+
+	bool _accel_blocked[ACCEL_COUNT_MAX] {};
+	bool _accel_stuck[ACCEL_COUNT_MAX] {};
+	sensor_accel_fifo_s _last_accel_fifo{};
+	matrix::Vector3f _last_accel[GYRO_COUNT_MAX] {};
+
+	bool _gyro_blocked[GYRO_COUNT_MAX] {};
+	bool _gyro_stuck[GYRO_COUNT_MAX] {};
+	sensor_gyro_fifo_s _last_gyro_fifo{};
+	matrix::Vector3f _last_gyro[GYRO_COUNT_MAX] {};
+
+	bool _baro_blocked{false};
+	bool _baro_stuck{false};
+
+	bool _mag_blocked{false};
+	bool _mag_stuck{false};
+
+	bool _gps_blocked{false};
+	bool _airspeed_blocked{false};
+
+	float _last_magx{0.0f};
+	float _last_magy{0.0f};
+	float _last_magz{0.0f};
+
+#if defined(ENABLE_LOCKSTEP_SCHEDULER)
+	px4::atomic<bool> _has_initialized {false};
+#endif
+
+	int _lockstep_component{-1};
+
+	DEFINE_PARAMETERS(
+		(ParamInt<px4::params::MAV_TYPE>) _param_mav_type,
+		(ParamInt<px4::params::MAV_SYS_ID>) _param_mav_sys_id,
+		(ParamInt<px4::params::MAV_COMP_ID>) _param_mav_comp_id
+	)
+};