Class BoardControllerDLL

python_package/brainflow/board_shim.py:159–592

class BoardControllerDLL(object):
    __instance = None

    @classmethod
    def get_instance(cls):
        if cls.__instance is None:
            cls.__instance = cls()
        return cls.__instance

    def __init__(self):
        if platform.system() == 'Windows':
            if struct.calcsize("P") * 8 == 64:
                dll_path = 'lib\\BoardController.dll'
            else:
                dll_path = 'lib\\BoardController32.dll'
        elif platform.system() == 'Darwin':
            dll_path = 'lib/libBoardController.dylib'
        else:
            dll_path = 'lib/libBoardController.so'
        try:
            resource = files(__name__).joinpath(dll_path)
            full_path = str(resource)
        except (TypeError, AttributeError):
            # Fallback for:
            # 1. Python < 3.9 (importlib.resources.files not available)
            # 2. NixOS/packaging edge cases where importlib.resources may not work
            import pkg_resources
            full_path = pkg_resources.resource_filename(__name__, dll_path)
        if os.path.isfile(full_path):
            dir_path = os.path.abspath(os.path.dirname(full_path))
            # for python we load dll by direct path but this dll may depend on other dlls and they will not be found!
            # to solve it we can load all of them before loading the main one or change PATH\LD_LIBRARY_PATH env var.
            # env variable looks better, since it can be done only once for all dependencies
            # for python 3.8 PATH env var doesnt work anymore
            try:
                os.add_dll_directory(dir_path)
            except (AttributeError, FileNotFoundError, OSError):
                # Best effort only: this may be unavailable or fail on some
                # platforms/runtime configurations; PATH/LD_LIBRARY_PATH is
                # updated below as a fallback.
                pass
            if platform.system() == 'Windows':
                os.environ['PATH'] = dir_path + os.pathsep + os.environ.get('PATH', '')
            else:
                os.environ['LD_LIBRARY_PATH'] = dir_path + os.pathsep + os.environ.get('LD_LIBRARY_PATH', '')
            self.lib = ctypes.cdll.LoadLibrary(full_path)
        else:
            raise FileNotFoundError(
                'Dynamic library %s is missed, did you forget to compile brainflow before installation of python package?' % full_path)

        self.prepare_session = self.lib.prepare_session
        self.prepare_session.restype = ctypes.c_int
        self.prepare_session.argtypes = [
            ctypes.c_int,
            ctypes.c_char_p
        ]

        self.is_prepared = self.lib.is_prepared