Using semaphores for a Bluepill based board project I looked at the documentation for support. The calls to use were described together with the optional return values. E.g. ETIMEDOUT, ECANCELED and EAGAIN.
I found the definitions for these defines in the file …/RIOT/cpu/avr8_common/avr_libc_extra/include/errno.h.
When it came to testing however it gave some problems. Turned out that the values that are returned by the sema calls were not that what is defined in the file mentioned above.
Via a test program the following values were found -ETIMEDOUT = -116, -ECANCELED=-140 and -EAGAIN = -11. Using these values have the expected results.
So I would like to ask to have the defines - and the correct values - in an include file and added to the RIOT-OS package. And of course an update to the documentation so that this file is also mentioned.
With kind regards, John