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Flight Software & Embedded Systems Framework

Note: auto-generated from comments in: ./API.cmake

API.cmake:

API of the fprime CMake system. These functions represent the external interface to all of the fprime CMake system. Users and developers should understand these functions in order to perform basic CMake setup while building as part of an fprime project.

The standard patterns include:

  • Add a directory to the fprime system. Use this in place of add_subdirectory to get cleanly organized builds.
  • Register an fprime module/executable/ut to receive the benefits of autocoding.
  • Register an fprime build target/build stage to allow custom build steps. (Experimental)

Macro restrict_platforms:

Restricts a CMakeLists.txt file to a given list of platforms. This prevents usage on platforms for which the module is incapable of being used and replaces the historical pattern of an if-tree detecting unsupported platforms.

Usage: restrict_platforms(Linux Darwin) # Restricts to Linux and Darwin platforms

Args: ARGN: list of platforms that are supported

Macro prevent_prescan:

Prevents a CMakeLists.txt file from being processed in the prescan phase of the project. Will generate fake targets for all those targets specified to ensure that dependencies may be attached to these targets in the larger system.

Usage: prevent_prescan(target1 target2 …) # Generate fake targets and skip prescan

Args: ARGN: list of targets to synthesize

Function add_fprime_subdirectory:

Adds a subdirectory to the build system. This allows the system to find new available modules, executables, and unit tests. Every module, used or not, by the deployment/root CMAKE file should be added as a subdirectory somewhere in the tree. CMake’s dependency system will prevent superfluous building, and add_fprime_subdirectory calls construct the super-graph from which the build graph is realized. Thus it is inconsequential to add a subdirectory that will not be used, but all code should be found within this super-graph to be available to the build.

Every subdirectory added should declare a CMakeLists.txt. These in-turn may add their own sub- directories. This creates a directed acyclic graph of modules, one subgraph of which will be built for each executable/module/library defined in the system. The subgraph should also be a DAG.

This directory is computed based off the closest path in FPRIME_BUILD_LOCATIONS. It must be set to be used. Otherwise, an error will occur. EXCLUDE_FROM_ALL can also be supplied. See: https://cmake.org/cmake/help/latest/command/add_fprime_subdirectory.html

Note: Replaces CMake add_subdirectory call in order to automate the [binary_dir] argument. fprime subdirectories have specific binary roots to avoid collisions, and provide for the standard fprime #include paths rooted at the root of the repo.

Arguments:

  • FP_SOURCE_DIR: directory to add (same as add_directory)
  • EXCLUDE_FROM_ALL: (optional) exclude any targets from ‘all’. See: https://cmake.org/cmake/help/latest/command/add_fprime_subdirectory.html

Function register_fprime_module:

Registers a module using the fprime build system. This comes with dependency management and fprime autocoding capabilities. The caller should first set two variables before calling this function to define the autocoding and source inputs, and (optionally) any non-standard link dependencies.

Required variables (defined in calling scope):

  • SOURCE_FILES: cmake list of input source files. Place any “.fpp”, “.c”, “*.cpp” etc files here. This list will be split into autocoder inputs, and hand-coded sources based on the name/type.

i.e.:

set(SOURCE_FILES
    MyComponent.fpp
    SomeFile.cpp
    MyComponentImpl.cpp)
  • MOD_DEPS: (optional) cmake list of extra link dependencies. This is optional, and only needed if non-standard link dependencies are used, or if a dependency cannot be inferred from the include graph of the autocoder inputs to the module. If not set or supplied, only fprime inferable dependencies will be available. Link flags like “-lpthread” can be added here as well. Do NOT supply executable targets in MOD_DEPS. See: register_fprime_executable for alternatives.

i.e.:

set(MOD_DEPS
    Os
    Module1
    Module2
    -lpthread)

Standard add_fprime_module Example

Standard modules don’t require extra modules, and define both autocoder inputs and standard source files. Thus, only the SOURCE_FILE variable needs to be set and then the register call can be made. This is the only required lines in a module CMakeLists.txt.

set(SOURCE_FILE
    MyComponent.fpp
    SomeFile.cpp
    MyComponentImpl.cpp)

register_fprime_module()

Non-Autocoded and Autocode-Only Modules Example

Modules that do not require autocoding need not specify *.xml files as source. Thus, code-only modules just define *.cpp. Note: dependency inference is only done when autocoder inputs (.fpp, .xml) are supplied.

set(SOURCE_FILE
    SomeFile1.cpp
    Another2.cpp)

register_fprime_module()

Modules requiring only autocoding may just specify *.xml files.

set(SOURCE_FILE
    MyComponent.fpp)

register_fprime_module()

Specific Dependencies and Linking in Modules Example

Some modules need to pick a specific set of dependencies and link flags. This can be done with the MOD_DEPS variable. This feature can be used to pick specific implementations for some fprime modules that implement to a generic interface like the console logger implementation.

set(SOURCE_FILE
    MyComponent.fpp
    SomeFile.cpp
    MyComponentImpl.cpp)

set(MOD_DEPS
    Module1
    -lpthread)

register_fprime_module()

Function register_fprime_executable:

Registers an executable using the fprime build system. This comes with dependency management and fprime autocoding capabilities. This requires three variables to define the executable name, autocoding and source inputs, and (optionally) any non-standard link dependencies.

Note: this is not intended for deployment executables (e.g. an fprime binary) but rather for utilities, helper executables and tools. To register a deployment binary see register_fprime_deployment.

Executables will automatically install itself and its dependencies into the out-of-cache build artifacts directory, specified by the FPRIME_INSTALL_DEST variable, when built.

Required variables (defined in calling scope):

  • EXECUTABLE_NAME: (optional) executable name supplied. If not set, nor passed in, then FPRIME_CURRENT_MODULE from the CMake definitions is used.

  • SOURCE_FILES: cmake list of input source files. Place any “.fpp”, “.c”, “*.cpp” etc. files here. This list will be split into autocoder inputs and sources. i.e.: 
    set(SOURCE_FILES
  MyComponent.fpp
  SomeFile.cpp
  MyComponentImpl.cpp)
  • MOD_DEPS: (optional) cmake list of extra link dependencies. This is optional, and only needed if non-standard link dependencies are used, or if a dependency cannot be inferred from the include graph of the autocoder inputs to the module. If not set or supplied, only fprime inferable dependencies will be available. Link flags like “-lpthread” can be here.

i.e.:

set(MOD_DEPS
    Module1
    Module2
    -lpthread)

Note: this operates almost identically to register_fprime_module with respect to the variable definitions. The difference is this call will yield an optionally named linked binary executable.

Caveats

Executable targets should not be supplied as dependencies through MOD_DEPS (e.g. to register_fprime_deployment). Doing so may cause problems with final linking of other executables due to multiple main function definitions. A better model would be to add a CMake only dependency without using MOD_DEPS.

Note: these errors are definition order dependent and thus users should not supply executables through MOD_DEPS even if it seems to work correctly.

i.e.:

set(SOURCE_FILES "tool.c")
register_fprime_executable(TOOL)
...
...
register_fprime_deployment(MY_DEPLOYMENT)
add_dependencies(MY_DEPLOYMENT TOOL) # CMake only dependency

Function register_fprime_deployment:

Registers an deployment using the fprime build system. This comes with dependency management and fprime autocoding capabilities. This requires two variables to define autocoding and source inputs, and (optionally) any non-standard link dependencies.

An executable will be created and automatically install itself and its dependencies into the out-of-cache build artifacts directory, specified by the FPRIME_INSTALL_DEST variable, when built. This will automatically run all deployment targets such that the standard deployment will be built (e.g. the dictionary will be built).

This is typically called from within the top-level CMakeLists.txt file that defines a deployment.

Required variables (defined in calling scope):

  • SOURCE_FILES: cmake list of input source files. Place any “.fpp”, “.c”, “*.cpp” etc. files here. This list will be split into autocoder inputs and sources. i.e.: 
    set(SOURCE_FILES
  MyComponent.fpp
  SomeFile.cpp
  MyComponentImpl.cpp)
  • MOD_DEPS: cmake list of extra link dependencies. This is almost always required to supply the topology module. Other entries are only needed when they cannot be inferred from the model (e.g. linker flags). Do NOT supply executable targets in MOD_DEPS. See: register_fprime_executable for alternatives.

i.e.:

set(MOD_DEPS
    ${FPRIME_CURRENT_MODULE}/Top
    Module1
    Module2
    -lpthread)

Note: this operates almost identically to register_fprime_executable and register_fprime_module with respect to the variable definitions. The difference is deployment targets will be run (e.g. dictionary generation), and the executable binary will be named after the module, or if project when defined directly in a project CMakeLists.txt

Standard fprime Deployment Example

To create a standard fprime deployment, an the user must call register_fprime_deployment() after defining SOURCE_FILES and MOD_DEPS.

set(SOURCE_FILES
  "${CMAKE_CURRENT_LIST_DIR}/Main.cpp"
)
# Note: supply dependencies that cannot be detected via the model here.
set(MOD_DEPS
  ${FPRIME_CURRENT_MODULE}/Top
)
register_fprime_deployment()

Function register_fprime_ut:

Registers an executable unit-test using the fprime build system. This comes with dependency management and fprime autocoding capabilities. This requires three variables defining the unit test name, autocoding and source inputs for the unit test, and (optionally) any non-standard link dependencies.

Note: This is ONLY run when the BUILD_TESTING is enabled. Unit testing is restricted to this build type as fprime sets additional flags when building for unit tests.

Required variables (defined in calling scope):

  • UT_NAME: (optional) executable name supplied. If not supplied, or passed in, then the _ut_exe will be used.

  • UT_SOURCE_FILES: cmake list of UT source files. Place any “.fpp”, “.c”, “*.cpp” etc. files here. This list will be split into autocoder inputs or sources. These sources only apply to the unit test.

i.e.:

set(UT_SOURCE_FILES
    MyComponent.fpp
    SomeFile.cpp
    MyComponentImpl.cpp)
  • UT_MOD_DEPS: (optional) cmake list of extra link dependencies. This is optional, and only needed if non-standard link dependencies are used. If not set or supplied, only fprime detectable dependencies will be available. Link flags like “-lpthread” can be supplied here.

i.e.:

set(UT_MOD_DEPS
    Module1
    Module2
    -lpthread)

Note: this is typically called after any other register calls in the module.

  • UT_AUTO_HELPERS: (optional) When set ON, a test helper file will be generated that auto-codes the connect ports and init components methods. This removes the maintenance overhead for these functions. ON additionally adds test source directories to the include path for the unit test target. When set to OFF, this helper file will be created when generating implementation templates allowing users to modify these files. Default: OFF

Unit-Test Example

A standard unit test defines only UT_SOURCES. These sources have the test cpp files and the model .fpp of the module being tested. This is used to generate the GTest harness.

set(UT_SOURCE_FILES
  "${FPRIME_FRAMEWORK_PATH}/Svc/CmdDispatcher/CommandDispatcher.fpp"
  "${CMAKE_CURRENT_LIST_DIR}/test/ut/CommandDispatcherTester.cpp"
  "${CMAKE_CURRENT_LIST_DIR}/test/ut/CommandDispatcherImplTester.cpp"
)
register_fprime_ut()

Macro register_fprime_target:

This function allows users to register custom build targets into the build system. These targets are defined in a CMake file and consist of three functions that operate on different parts of the build: global, per-module, and per-deployment. See: Targets.

This function takes in either a file path to a CMake file defining targets, or an short include path that accomplishes the same thing. Note: make sure the directory is on the CMake include path to use the second form. The supplied file should define three functions: add_global_target, add_module_target, and add_deployment_target.

TARGET_FILE_PATH: include path or file path file defining above functions

macro(register_fprime_target TARGET_FILE_PATH) if (CMAKE_DEBUG_OUTPUT) message(STATUS “[target] Registering custom target: ${TARGET_FILE_PATH}”) endif() register_fprime_list_helper(“${TARGET_FILE_PATH}” FPRIME_TARGET_LIST) endmacro(register_fprime_target)

Macro register_fprime_list_helper:

Helper function to do the actual registration. Also used to side-load prescan to bypass the not-on-prescan check.

Macro register_fprime_build_autocoder:

This function allows users to register custom autocoders into the build system. These autocoders will execute during the build process. An autocoder is defined in a CMake file and must do three things:

  1. Call one of autocoder_setup_for_individual_sources() or autocoder_setup_for_multiple_sources() from file scope
  2. Implement <autocoder name>_is_supported(AC_POSSIBLE_INPUT_FILE) returning true the autocoder processes given source
  3. Implement <autocoder name>_setup_autocode AC_INPUT_FILE) to run the autocoder on files filter by item 2. See: Autocoders.

This function takes in either a file path to a CMake file defining an autocoder target, or an short include path that accomplishes the same thing. Note: make sure the directory is on the CMake include path to use the second form.

TARGET_FILE_PATH: include path or file path file defining above functions

Function create_implementation_interface:

Helper function to create implementation interface library once and only once to ensure it exists.

IMPLEMENTATION: implementation library name (resolved)

Function require_fprime_implementation:

Designates that the current module requires a separate implementation in order for it to function properly. As an example, Os requires an implementation of Os_Task. These implementations must be set via choose_fprime_implementation in the platform and may be overridden in in the executable/deployment.

IMPLEMENTATION: implementation module name that must be covered REQUESTER: (optional) the requester of the implementation. Default: ${FPRIME_CURRENT_MODULE}

Function register_fprime_implementation:

Designates that the given implementor implements the required implementation. As an example Os_Task_Posix implements Os_Task. These implementations must be set via choose_fprime_implementation in the platform and may be overridden in in the executable/deployment.

IMPLEMENTATION: implementation module name that is implemented by IMPLEMENTOR IMPLEMENTOR: implementor of IMPLEMENTATION

Function choose_fprime_implementation:

Designates that the given implementor is the selected implementor for the needed implementation. Platforms must call this function once for each defined IMPLEMENTATION. An executable/deployment/unit-test may call this function to set a specific implementor for any needed implementation

IMPLEMENTATION: implementation module name that is implemented by IMPLEMENTOR IMPLEMENTOR: implementor of IMPLEMENTATION

Next Topics:

  • Setting Options: Options are used to vary a CMake build.
  • Adding Deployments: Deployments create fprime builds.
  • Adding Modules: Modules register fprime Ports, Components, etc.
  • Creating Toolchains: Toolchains setup standard CMake Cross-Compiling.
  • Adding Platforms: Platforms help fprime set Cross-Compiling specific items.
  • Adding Targets: Targets for help defining custom build targets
  • Implementation Packages Design: Implementation Packages