Instead of just having a max count for joystick values, there's an available mask of values. This is because in the future we're expecting there to be holes in the list of available buttons and axes. This updates everything to support that scenario.
Also, Joystick buttons, axes, and POVs all now start at 0 instead of 1.
As string_view operations on std::map<std::string> won't be integrated
until C++26, placeholder implementations are used which are less efficient
in a couple of situations (e.g. insert with hint).
Currently in the entire C API of WPILib we have ~8 different ways of handling strings. The C API actually isn't built for pure C callers (We don't actually have any of those). Instead, they're built for interop between languages like LabVIEW and C# which can talk to C API's directly.
For output parameters, the choice was fairly obvious. An output struct containing a const string pointer and a length makes the most sense. Its easy to use these from most other languages, and doesn't require special null termination handling. Freeing these is also easy, as if you ever receive one of these string structures, theres just a single function call to free it.
Input parameters are a bit more complex. To be used from pure C, and from LabVIEW, a null terminated string is the best in most cases. However, null terminated strings in general have a lot of downsides. Additionally, from LabVIEW there are other considerations around encoding that having a wrapper struct helps make a bit easier. From a language like C#, a wrapper struct is by far the easiest, as custom marshalling can make it trivial to marshal both UTF8 and UTF16 strings down.
The final consideration is its nice to have an identical concept for both input and output. It makes the rules fairly easy to understand.
WPILib will not have any APIs that manipulate a string allocated externally. This means WPI_String can be const, as across the boundary it is always const.
If a WPILib API takes a const WPI_String*, WPILib will not manipulate or attempt to free that string, and that string is treated as an input. It is up to the caller to handle that memory, WPILib will never hold onto that memory longer than the call.
If a WPILib API takes a WPI_String*, that string is an output. WPILib will allocate that API with WPI_AllocateString(), fill in the string, and return to the caller. When the caller is done with the string, they must free it with WPI_FreeString().
If an output struct contains a WPI_String member, that member is considered read only, and should not be explicitly freed. The caller should call the free function for that struct.
If an array of WPI_Strings are returned, each individual string is considered read only, and should not be explicitly freed. The free function for that array should be called by the caller.
If an input struct containing a WPI_String, or an input array of WPI_Strings is passed to WPILib, the individual strings will not be manipulated or freed by WPILib, and the caller owns and should free that memory.
Callbacks also follow these rules. The most common is a callback either getting passed a const WPI_String* or a struct containing a WPI_String. In both of these cases, the callback target should consider these strings read only, and not attempt to free them or manipulate them.
The default state for the DS in the simulated HAL is changed to disconnected.
The FMS view is now only editable in DS disconnected state.
This enables more robot and field-like testing of robot code, as the
alliance color and other parameters start in invalid states and are
only set when the DS connects.
The current DS thread model has some pretty major issues. It makes it difficult to know if all data is from the same remote packet, and if the data changes while the robot loop is running. Additionally, the DS thread is used for a few other things (MotorSafety and State Tracking for EducationalRobot). This also makes sim difficult, as user code has to wait for the thread to know it has new data.
This change completely rethinks how threading works in the driver station model.
First, the DS HAL system receives a new data callback, either from Netcomm or DriverStationSim. Inside the context of this callback, all the low latency data is read and put into a cache. Doing some investigation on the robot side, this is perfectly safe to do, and also ensures a ds packet will not be parsed before we finish reading the current packet data.
After all data is read, the cache is swapped with a 2nd buffer. This buffer just stores the data, none of the HAL DS calls read from this buffer. An event is then fired, stating there is new data ready to go.
Robot code calls HAL_UpdateDSData(). This swaps the 2nd buffer with a 3rd buffer, which always contains the current data. This data will not be updated until HAL_UpdateDSData is called again. Which solves the state problem.
The high level driver station classes have. an updateData() call, which calls HAL_UpdateDSData, and then update button state variables, then data log and update the NT FMS data table (Java also caches across the JNI boundary here, but that could trivially be removed). An extra event provider is provided, allowing other threads to know when this call has been completed.
IterativeRobotBase calls DS.updateData() at the beginning of each loop, and only once per loop. This means all commands will always have the same state.
All of this means there is no longer a DS thread. Everything happens synchronously. This means Sim and testing is easier, as you can just call DriverStationSim.NotifyNewData(), and then DriverStation.UpdateData(), and you can guarantee that all the DriverStation.*** data is up to date.
As for Motor Safety and Educational Robot State Handling, those can all be handled by their own threads. The Educational Thread only needs to run under EducationalRobot, and MotorSafety will only be started if there is a motor safety object enabled.
The real robot has match time set to -1.0 until it's enabled, and then
counts down. Disabling the robot sets the time to -1.0.
The sim GUI has been updated to add preset buttons for auto and teleop
match times. The enable match timing checkbox has been removed as it's
no longer required.
The DS socket plugin has also been fixed to properly initialize
matchTime to -1.0 and reset it to -1.0 on disable.
- Twine, StringRef, Format, and NativeFormatting have been removed
- Logging now uses fmtlib style formatting
- Nearly all uses of wpi::outs/errs have been replaced with fmt::print() or
std::puts()/std::fputs() (for unformatted strings).
- A wpi/fmt/raw_ostream.h header has been added to enable
fmt::print() with wpi::raw_ostream
This makes code easier to read and more consistent between C++ and Java.
Also update clang-format settings to always add a line break (even if no braces are used).
This is a breaking change to the WebSockets layer to align it with
recent specification documentation work.
To support this, HAL SimValue changed readonly to a direction enum.
This allows specifying bidirectional in addition to input and output.
The SimValue change is specifically designed to avoid API and ABI breakage.
This is completely transparent in C++; in Java a new callback class was added,
and the old readonly functions have been marked deprecated.
A new SimValue creation function for enums allows specifying double values
for each enum value, not just strings. This allows mapping enum values to
doubles in the WebSockets layer.
A ":" in the SimDevice name now maps it to different WebSocket types (e.g.
"Accel:Name" becomes type "Accel", device "Name"). The type is hidden
in the GUI.
Other WebSockets changes:
* Implemented match_time and game_data
* Added joystick rumble data
* Added builtin accelerometer support
* SimValue enums are mapped to string and double value on WS interface
* Added WebSockets protocol specification
* Added READMEs
Based on run of include-what-you-use.org to identify unused include files in various .h and .cpp files.
The changes mostly fall into 3 categories:
- Actually unused includes - copy-paste errors, not removing includes after cleaning up code, etc
- A too-broad include used where a more specific (and hopefully smaller) header will do
- Interface .h files including headers only needed by the .cpp implementation - moving from .h to .cpp
will mean that code which uses the .h doesn't pay the price of processing the header file they don't need
