internal static extern IntPtr cl_engine_get_str(IntPtr engine, cl_engine_field field, ref int err);
internal static extern long cl_engine_get_num(IntPtr engine, cl_engine_field field, ref int err);
internal static extern int cl_engine_set_str(IntPtr engine, cl_engine_field field, string str);
internal static extern int cl_engine_set_num(IntPtr engine, cl_engine_field field, long num);
internal static extern IntPtr cl_engine_get_str(IntPtr engine, cl_engine_field field, IntPtr err);
internal static extern long cl_engine_get_num(IntPtr engine, cl_engine_field field, IntPtr err);