Add support for FreeRTOS and lwIP (#166)

Add support for FreeRTOS and lwIP

Signed-off-by: Jeroen Koekkoek <jeroen@koekkoek.nl>

src/cmake/modules/GenerateDummyExportHeader.cmake

@@ -0,0 +1,51 @@
+# Copyright(c) 2006 to 2018 ADLINK Technology Limited and others
+#
+# This program and the accompanying materials are made available under the
+# terms of the Eclipse Public License v. 2.0 which is available at
+# http://www.eclipse.org/legal/epl-2.0, or the Eclipse Distribution License
+# v. 1.0 which is available at
+# http://www.eclipse.org/org/documents/edl-v10.php.
+#
+# SPDX-License-Identifier: EPL-2.0 OR BSD-3-Clause
+
+function(GENERATE_DUMMY_EXPORT_HEADER _target)
+  set(_opts)
+  set(_single_opts BASE_NAME EXPORT_FILE_NAME)
+  set(_multi_opts)
+  cmake_parse_arguments(_args "${_opts}" "${_single_opts}" "${_multi_opts}" ${ARGN})
+
+  if(NOT _target)
+    message(FATAL_ERROR "Target not specified")
+  elseif(NOT TARGET ${_target})
+    message(FATAL_ERROR "Target ${_target} does not exist")
+  endif()
+
+  string(TOUPPER _target_uc "${_target}")
+  string(TOLOWER _target_lc "${_target}")
+
+  if(_args_EXPORT_FILE_NAME)
+    set(_path "${_args_EXPORT_FILE_NAME}")
+  else()
+    set(_path "${CMAKE_CURRENT_BINARY_DIR}/${_target_lc}_export.h")
+  endif()
+
+  if(_args_BASE_NAME)
+    string(TOUPPER "${_args_BASE_NAME}" _base_name)
+  else()
+    set(_base_name "${_target_uc}")
+  endif()
+
+  get_filename_component(_dir  "${_path}" DIRECTORY)
+  get_filename_component(_file "${_path}" NAME)
+
+  if(NOT IS_DIRECTORY "${_dir}")
+    file(MAKE_DIRECTORY "${_dir}")
+  endif()
+
+  set(_content
+"/* Dummy export header generated by CMake. */
+#define ${_base_name}_EXPORT\n")
+
+  file(WRITE "${_path}" "${_content}")
+endfunction()
+