Testing shows that for frequencies which the esp8266 can handle -- up to
about 1kHz -- `machine.time_pulse_us()` now gives more accurate results.
Prior to this commit it would measure on average about 1us lower, but now
the average is much closer to the true value. For example a pulse that is
1000us long, it would measure between 998 and 1000us. Now it measures
between 999us and 1001us.
Signed-off-by: Damien George <damien@micropython.org>
This implementation is based on the esp8266 custom implementation, and
further optimised for size and accuracy.
Testing on PYBD_SF2 and RPI_PICO2_W shows that it is at least as good as
the original implementation in performance.
Signed-off-by: Damien George <damien@micropython.org>
The STATIC macro was introduced a very long time ago in commit
d5df6cd44a. The original reason for this was
to have the option to define it to nothing so that all static functions
become global functions and therefore visible to certain debug tools, so
one could do function size comparison and other things.
This STATIC feature is rarely (if ever) used. And with the use of LTO and
heavy inline optimisation, analysing the size of individual functions when
they are not static is not a good representation of the size of code when
fully optimised.
So the macro does not have much use and it's simpler to just remove it.
Then you know exactly what it's doing. For example, newcomers don't have
to learn what the STATIC macro is and why it exists. Reading the code is
also less "loud" with a lowercase static.
One other minor point in favour of removing it, is that it stops bugs with
`STATIC inline`, which should always be `static inline`.
Methodology for this commit was:
1) git ls-files | egrep '\.[ch]$' | \
xargs sed -Ei "s/(^| )STATIC($| )/\1static\2/"
2) Do some manual cleanup in the diff by searching for the word STATIC in
comments and changing those back.
3) "git-grep STATIC docs/", manually fixed those cases.
4) "rg -t python STATIC", manually fixed codegen lines that used STATIC.
This work was funded through GitHub Sponsors.
Signed-off-by: Angus Gratton <angus@redyak.com.au>
The contents of machine_bitstream.h, machine_pinbase.h, machine_pulse.h and
machine_signal.h have been moved into extmod/modmachine.h.
Signed-off-by: Damien George <damien@micropython.org>
machine.time_pulse_us() is intended to provide very fine timing, including
while working with signal bursts, where each transition is tracked in row.
Throwing and handling an exception may take too much time and "signal loss".
So instead, in case of a timeout, just return negative value. Cases of
timeout while waiting for initial signal stabilization, and during actual
timing, are recognized.
The documentation is updated accordingly, and rewritten somewhat to clarify
the function behavior.
