--legacyalign, --no_legacyalign are deprecated from ARMC6 compiler, in order to
remove deprecated flags all linker files should strictly align to 8-byte boundary
For STM32 targets using a 32-bit timer for the microsecond ticker, the
driver did not properly handle timestamps that are in the past. It
would just blindly set the compare register to the requested timestamp,
resulting in the interrupt being serviced up to 4295 seconds late
(i.e. after the 32-bit timer counts all the way around to hit the
timestamp again).
This problem can easily be reproduced by creating a Timeout object
then calling the timeout's attach_us() member function to attach a
callback with a timeout of 0 us. The callback will not get called for
over 2147 seconds, and possibly up to 4295 seconds late if no other
microsecond ticker events are getting scheduled in the meantime.
Now, after the compare register has been set, the timestamp is checked
against the current time to see if the timestamp is in the past, and
if so, the compare event is manually set.
NOTE: By checking if the timestamp is in the past after configuring the
capture register, we ensure proper handling in the case where the timer
updates past the timestamp while setting the capture register.
Senthil Ramakrishnan
Deepika
bcostm
jeromecoutant
Jimmy Brisson
Martin Kojtal
Rob Meades
Sam Grove
Bradley Scott
Bartek Szatkowski