C++ FMUs

This is a repository of FMUs written in plain C++ using the CPPFMU framework.

How to build

NOTE: After cloning the repository for the first time, remember to initialise and update the CPPFMU submodule:

git submodule init
git submodule update

The build procedure is fairly standard CMake. First, create a build directory somewhere. Here, we'll assume that it is created in the top-level source directory:

mkdir build
cd build

Then, run CMake twice, once to genereate the buildsystem and once to build the code:

cmake ..
cmake --build .

Assuming everything went well, the generated FMUs will be located in the build directory.

Checking FMU compliance

It's always a good idea to use the FMU Compliance Checker to verify that FMUs are FMI compliant. To activate a set of tests that run the FMU checker on each generated FMU, enable the FMU_CHECK_COMPLIANCE option. If the FMU Compliance Checker is not installed in a standard location, you may also have to specify where to find it. Here is an example:

cmake -DFMU_CHECK_COMPLIANCE=ON -DCMAKE_PREFIX_PATH=/opt/fmu_checker ..
cmake --build .
ctest

Multi-platform FMUs

The tools/MergeFMUs.cmake script is designed to merge FMUs compiled for different platforms into one multi-platform FMU.

The most straightforward way to compile the FMUs for different platforms is to actually perform the compilation on the platforms in question, and then gather the FMUs in one place for merging. Cross compilation is another, albeit more involved, possibility.

It is usually easy to compile for different processor architectures (i.e., 32- and 64-bit processors) on a single platform, though.

With GCC and CMake's Makefile generator, the default target architecture is usually the one the operating system was built for. To compile for a different one, ensure that you have installed the g++-multilib package, and then set the CMake variable CMAKE_CXX_FLAGS to -m32 or -m64 in the generation command in the previous section. Here is how to build for both architectures on a 64-bit machine:

mkdir build64 build32
cd build64
cmake ..
cmake --build .
cd ../build32
cmake -DCMAKE_CXX_FLAGS=-m32 ..
cmake --build .

With the Visual Studio generators, the default is usually to build in 32-bit mode regardless of OS architecture. To switch to 64-bit mode, use the -A option:

mkdir build32 build64
cd build32
cmake ..
cmake --build .
cd ../build64
cmake -A x64 ..
cmake --build .

Once the various platform- and/or architecture-specific FMUs have been built, they can be merged into one using the MergeFMUs script like in this example:

cmake "-DINPUT_FMUS=build32/foo.fmu;build64/foo.fmu;/mnt/winbuild/foo.fmu" -DOUTPUT_FMU=foo.fmu -P tools/MergeFMUs.cmake