Replace direct accesses to sched_active_thread and sched_active_pid with
the helper functions thread_getpid() and thread_get_active(). This serves
two purposes:
1. It makes accidental writes to those variable from outside core less likely.
2. Casting off the volatile qualifier is now well contained to those two
functions
When using convert_frac to slow down a timer, the extension machinery is
used to prevent converting values that would be larger than, after
conversion, 2**32. In order to calculate the maximum value, UINT32_MAX
is converted.
Previously, this was mistakenly converted by multiplying with the
fraction used to scale up a value. E.g., when using convert_frac to
slow down a 1us timer to provide a 1ms timer, UINT32_MAX was multiplied
by 1000. As the result is used % UINT32_MAX, this lead to a wrong value
close to UINT32_MAX, as ((UINT32_MAX * N) % UINT32_MAX = (UINT32_MAX - N - 1)).
This PR fixes the calculation so max_value is determined by multiplying
with the fraction used to scale down a value.
ztimer_clock are meant to be chained. At the end of the chaine
there is always a timer device object (periph_rtt/rtc/timer).
Since ZTIMER_MSEC and ZTIMER_USEC can be the scaled/shifted with
respect to the base periph_rtt/rtc/timer it makes sense to chain
other ZTIMER_XXX on top of the base rtc/timer/rtt in order to avoid
chained convertions.
Previously, ztimer would happily set an absolute RTT alarm value that exceeds
RTT's maximum value (though not a longer interval), as the `val` was
simply added to `rtt_get_counter()`.
This commit ensures that the target value wraps around RTT_MAX_VALUE.
Fixes#13920.
With #10970 only existing *.c files will be added to SRC when using
the SUBMODULES mechanism, so SUBMODULES_NOFORCE (used to filter out
non existing source files) is now redundant so remove the usage.
This commit adds logic to make xtimer use ztimer_usec as backend
(instead of periph_timer). This allows ztimer_usec and xtimer to
coexist. It also allows xtimer to profit from eventually implemented
power mode blocking in ztimer's periph_timer backend.
