This changes the HAL notifier interface to:
- Use wpiutil signal objects. This means waiting is done through the
`WPI_WaitObject` API instead of a dedicated function and allows for
higher level code to simultaneously wait on notifiers and other events.
- Interval timers are supported at the HAL layer
- Handlers are now required to acknowledge notifications. This is
invisible to users unless they're directly using the HAL API.
- For interval timers, an overrun count is maintained to detect if the
handler didn't acknowledge
The underlying implementation still uses condition variables for the
actual waiting. In basic testing using this approach seemed to be lower
jitter than timerfd.
Currently, the simulation and systemcore implementations are nearly
identical except for a few additional sim hook bits. This could be
refactored, but keeping them separate may make sense to keep the
systemcore implementation easy to read and reason about, or if we ever
choose to use a different underlying timer implementation on systemcore.
The simulation side API is unchanged in form but does change in
function--waiting for notifiers now only waits for currently running (or
newly signaled) notifiers to acknowledge. To avoid a race condition in
sim stepTiming, users of the low level API must make any alarm updates
(especially for one-shot alarms) prior to acknowledging the previous
alarm.
The only current use of the interval timer feature is the `Notifier`
class. The `TimedRobot` implementation still uses a single notifier and
its own interval timing logic to ensure consistent callback order. Using
separate notifiers for each user-level interval would substantially
increase complexity. `Watchdog` also doesn't use the interval timer, as
it's looking for an amount of time since the last `set` call rather than
a recurring interval time.
To reduce flicker, the sim GUI uses a fade out when a timeout goes from
set to unset.
This fixes tsan for wpilib and commands, and also fixes some spurious
test failures.
Support joystick outputs, including Rumble and LEDs.
Also requires an update to Joystick descriptors, as that has also
changed in mrccomm to support showing what outputs are supported.
After replacing the remaining include guards with `#pragma once`, I was
able to merge all the wpiformat configs into one file in the repo root.
This should make the config easier to reason about and maintain in the
future.
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.
Many LED strips use different color order (GRB in particular is common).
This makes the change at the HAL level. This solves 2 problems; first, no code needs to change in the high level drivers, which was challenging for C++, and second, simulation will behave properly as no conversion is needed. The HAL will accept an array of data objects in the same order no matter what the selected output order is, and will convert before sending it to the FPGA for output.
To accomplish this, NEON bulk load/interleave instructions are utilized. The low level implementation (load, store, and alignment functions) come from the Simd Library. The high level implementations are inspired by the image conversion functions in the simd library, but have diverged significantly.
Much of the implementation uses templates and inlined functions rather than runtime parameters; This is a trade off between the size of the generated code and the amount of function calls done at runtime. Currently, the entire conversion operation is inlined.
