By default on Windows 11, power throttling will increase timer resolution
if a window is occluded. Disable that behavior. Also enable high QOS to
achieve maximum performance and turn off power saving.
Also use internal APIs to set timer precision to 500 us if available.
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.
We now use a wrapper (wpi::print) to catch exceptions since we can't patch
std::print() to not throw when we ultimately migrate to it.
fmtlib and std format/print throw the same exceptions and always have. We previously patched fmt::print() to not throw a write failure exception, but we can't do that for std::print(); wpi::print() is the migration plan.
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.
fmtlib uses consteval format string processing, which makes it more
efficient than std::snprintf().
snprintf()s in libuv, mpack, processstarter, and wpigui were left alone.
processstarter uses stdlib only, and wpigui only depends on imgui.
fmt::format_to_n() is analogous to std::format_to_n()
(https://en.cppreference.com/w/cpp/utility/format/format_to_n)
wpi::format_to_n_c_str() is a wrapper which adds the trailing NUL.
Setting one will set the others, like it does in real hardware.
Add tests for boundary conditions and conversions.
Update PWM sendable implementation to include all forms.
Fixes#5264Fixes#3606
HAL_SetAddressableLEDBitTiming swapped high and low timings for whatever
was written to it. This fixes that bug.
Additionally, the API has been updated to take high time first, and then
low time. This is due to this being the physical data format, so having
the API match is clearer.
Additionally, update the docs with the defaults.
During HAL_Initialize, wait up to 100ms for a DS packet to be received. Then in RobotBase, right after calling HAL_Initialize, call each language's RefreshData function to force a high level DS update. If the DS is connected, will get joystick data. If there is no data, nothing different will happen, but in that case there's no joysticks anyway.
Using an atomic here means we are never going against a lock that is touchable from user code. That should make reading the DS data from the DS callback even safer.
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 existing raw time has an issue where it jumps around, as in the FPGA if the frequency is not a multiple or divisor of 25 Mhz it jumps around by 1 every second. While waiting on an FPGA change, update the API to make raw output give nanoseconds rather then a scaled value. This does a longer read cycle to get the correct value, but in the future if a fast FPGA function is added this can be easily changed.
SPI Mode setting was very broken. MSB and LSB sets did not work (MSB is the only one supported)
and if LSB was set (which was the default) the ioct to set clock phase would fail. This
deprecates all the individual functions, the LSB/MSB functions, and adds an SPI mode selection
function. This is usually more understandable, and shows up in a lot more documentation
The FPGA API takes microseconds directly, instead of a scaled value. Also add a new HAL level API to trigger multiple DIOs with the same pulse at once.
