283 lines
7.9 KiB
ReStructuredText
283 lines
7.9 KiB
ReStructuredText
.. include:: /substitutions.rst
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.. _cpp_cmake:
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C++ Example using CMake
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=======================
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In some situations, developers intend to implement software using the NuttX platform in
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a previously set hardware and configuration where it is not possible or allowed to make
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changes. In such situations, less contact with the operating source tree is better, where
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it is only used for the application.
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Some approaches are possible to do that today:
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* https://cwiki.apache.org/confluence/display/NUTTX/Building+NuttX+with+Applications+Outside+of+the+Source+Tree
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* https://www.programmersought.com/article/61604062421/
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We have been seen the increase of the use of C++ language in embedded systems application. And
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CMake (https://www.cmake.org) is the preferred build system used to build C++ projects. NuttX
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support C++ based projects.
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Using the 'build as a library' procedure of NuttX, it is possible to build NuttX
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applications using C++ language and also the cmake build tool.
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This document will show how to reimplement the hellocpp project using this cmake.
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Preparation
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-----------
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#. Base NuttX compilation changes
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For this example, load the configuration 'stm32f4discovery:testlibcxx' for building
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.. code-block:: console
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$ cd nuttx
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$ ./tools/configure.sh stm32f4discovery:testlibcxx
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In menuconfig, the main points to be changed on a typical NuttX configuration are the following:
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* Set RTOS Features -> Tasks and Scheduling -> Application entry point to 'hellocpp_main'
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* Build NuttX and generate the export
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.. code-block:: console
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$ make export
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Creating the project
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--------------------
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#. Create your project file structure
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The project structure is organized as follow:
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.. code-block:: console
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hellocpp/
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hellocpp/CMakeLists.txt
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hellocpp/cmake/stm32f4discovery.cmake
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hellocpp/nuttx-export-10.0.1/
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hellocpp/src/CMakeLists.txt
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hellocpp/src/main.cpp
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hellocpp/src/HelloWorld.h
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hellocpp/src/HelloWorld.cpp
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The directory 'nuttx-export-10.0.1' is the unzipped content from the file created during
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make export procedure done before.
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#. File contents
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* hellocpp/CMakeLists.txt
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.. code-block:: cmake
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cmake_minimum_required(VERSION 3.2...3.15)
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project(HelloCpp
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VERSION 1.0
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DESCRIPTION "Hello world C++ NuttX"
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)
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set(CMAKE_CXX_STANDARD 17)
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set(CMAKE_CXX_STANDARD_REQUIRED ON)
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# set(CMAKE_CXX_EXTENSIONS OFF)
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set(CMAKE_C_STANDARD 99)
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set(NUTTX_PATH "${CMAKE_SOURCE_DIR}/nuttx-export-10.0.1")
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include(cmake/stm32f4discovery.cmake)
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set(AC_COMMON_FLAGS "${AC_COMMON_FLAGS} -Wall -Wshadow -Wundef -fno-strict-aliasing -Os")
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set(AC_COMMON_FLAGS "${AC_COMMON_FLAGS} -D_DEBUG -D_LIBCPP_BUILD_STATIC -D_LIBCPP_NO_EXCEPTIONS ")
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set(AC_COMMON_FLAGS "${AC_COMMON_FLAGS} -fno-exceptions -fcheck-new -fno-rtti -pedantic ")
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set(AC_COMMON_FLAGS "${AC_COMMON_FLAGS} -nostdinc++")
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set(AC_DEFINES "${AC_DEFINES} -DCONFIG_WCHAR_BUILTIN")
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include_directories(
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src
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${NUTTX_PATH}/include
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${NUTTX_PATH}/include/libcxx
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${NUTTX_PATH}/arch/chip
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)
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set(EXE_NAME hellocpp)
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set(CMAKE_C_FLAGS "${CMAKE_C_FLAGS} ${AC_HW_FLAGS} ${AC_DEFINES}")
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set(CMAKE_CXX_FLAGS "${AC_HW_FLAGS} ${AC_DEFINES} ${AC_COMMON_FLAGS} ${AC_CXX_EXTRA_FLAGS}")
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if (PARAM_DEBUG)
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set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -g")
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endif()
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set(CMAKE_SKIP_RPATH ON)
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set(CMAKE_CXX_LINK_EXECUTABLE "${CMAKE_LINKER} ${AC_LINKER_FLAGS} -o ${EXE_NAME}.elf <OBJECTS> <LINK_LIBRARIES>")
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set(BUILD_SHARED_LIBS OFF)
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add_subdirectory(src)
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* hellocpp/cmake/stm32f4discovery.cmake
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.. code-block:: cmake
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set(CMAKE_SYSTEM_NAME Generic)
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set(CMAKE_SYSTEM_PROCESSOR arm)
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set(MCU_LINKER_SCRIPT "${NUTTX_PATH}/scripts/ld.script")
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set(COMPILER_PREFIX arm-none-eabi-)
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# cmake-format: off
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set(CMAKE_C_COMPILER ${COMPILER_PREFIX}gcc)
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set(CMAKE_CXX_COMPILER ${COMPILER_PREFIX}g++)
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set(CMAKE_AR ${COMPILER_PREFIX}ar)
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set(CMAKE_RANLIB ${COMPILER_PREFIX}ranlib)
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set(CMAKE_LINKER ${COMPILER_PREFIX}ld)
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set(CMAKE_ASM_COMPILER ${COMPILER_PREFIX}gcc)
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set(CMAKE_OBJCOPY ${COMPILER_PREFIX}objcopy)
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set(CMAKE_OBJDUMP ${COMPILER_PREFIX}objdump)
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set(CMAKE_SIZE ${COMPILER_PREFIX}size)
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set(CMAKE_FIND_ROOT_PATH_MODE_PROGRAM NEVER)
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set(CMAKE_FIND_ROOT_PATH_MODE_LIBRARY ONLY)
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set(CMAKE_FIND_ROOT_PATH_MODE_INCLUDE ONLY)
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set(CMAKE_FIND_ROOT_PATH_MODE_PACKAGE ONLY)
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set(CMAKE_TRY_COMPILE_TARGET_TYPE STATIC_LIBRARY)
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set(AC_HW_FLAGS "-mcpu=cortex-m4 -mthumb -mfloat-abi=soft ")
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set(AC_HW_FLAGS "${AC_HW_FLAGS} -isystem ${NUTTX_PATH}/include")
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set(AC_HW_FLAGS "${AC_HW_FLAGS} -pipe")
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set(AC_LINKER_FLAGS "--entry=__start -nostartfiles -nodefaultlibs -T${MCU_LINKER_SCRIPT}")
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* hellocpp/src/CMakeLists.txt
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.. code-block:: cmake
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set(HEADER_FILES
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HelloWorld.h
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)
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set(SOURCE_FILES
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HelloWorld.cpp
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)
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link_directories(${EXE_NAME} ${NUTTX_PATH}/libs)
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add_executable(${EXE_NAME} ${SOURCE_FILES} main.cpp ${HEADER_FILES})
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add_custom_command(
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TARGET ${EXE_NAME}
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POST_BUILD
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COMMAND ${CMAKE_OBJCOPY} ARGS -S -O binary ${CMAKE_BINARY_DIR}/${EXE_NAME}.elf ${CMAKE_BINARY_DIR}/${EXE_NAME}.bin
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)
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target_link_libraries(${EXE_NAME} --start-group)
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target_link_libraries(${EXE_NAME} sched)
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target_link_libraries(${EXE_NAME} drivers)
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target_link_libraries(${EXE_NAME} boards)
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target_link_libraries(${EXE_NAME} c)
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target_link_libraries(${EXE_NAME} mm)
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target_link_libraries(${EXE_NAME} arch)
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target_link_libraries(${EXE_NAME} xx)
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target_link_libraries(${EXE_NAME} apps)
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target_link_libraries(${EXE_NAME} fs)
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target_link_libraries(${EXE_NAME} binfmt)
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target_link_libraries(${EXE_NAME} board)
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target_link_libraries(${EXE_NAME} gcc)
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target_link_libraries(${EXE_NAME} supc++)
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target_link_libraries(${EXE_NAME} --end-group)
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* hellocpp/src/main.cpp
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.. code-block:: c++
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#include "HelloWorld.h"
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#include <nuttx/config.h>
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extern "C"
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{
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int hellocpp_main(void)
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{
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CHelloWorld *pHelloWorld = new CHelloWorld();
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pHelloWorld->HelloWorld();
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CHelloWorld helloWorld;
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helloWorld.HelloWorld();
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delete pHelloWorld;
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return 0;
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}
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}
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* hellocpp/src/HelloWorld.h
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.. code-block:: c++
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#ifndef HELLOWORLD_H_
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#define HELLOWORLD_H_
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#include "nuttx/config.h"
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class CHelloWorld
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{
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public:
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CHelloWorld();
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~CHelloWorld();
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bool HelloWorld(void);
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private:
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int mSecret;
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};
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#endif
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* hellocpp/src/HelloWorld.cpp
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.. code-block:: c++
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#include <cstdio>
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#include <string>
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#include "HelloWorld.h"
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CHelloWorld::CHelloWorld() {
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mSecret = 42;
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std::printf("Constructor: mSecret=%d\n",mSecret);
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}
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CHelloWorld::~CHelloWorld() {
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}
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bool CHelloWorld::HelloWorld(void) {
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std::printf("HelloWorld: mSecret=%d\n",mSecret);
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std::string sentence = "Hello";
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std::printf("TEST=%s\n",sentence.c_str());
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if (mSecret == 42) {
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std::printf("CHelloWorld: HelloWorld: Hello, world!\n");
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return true;
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}
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else {
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std::printf("CHelloWorld: HelloWorld: CONSTRUCTION FAILED!\n");
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return false;
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}
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}
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Building
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--------
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To launch build, you use the cmake procedure:
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.. code-block:: console
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$ mkdir build
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$ cd build
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$ cmake ..
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$ make
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And finally a bin file will be created to be loaded on the board.
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