I recently tried to bind Céu's wclock to the system clock of my microcontroller. I do not want to implement the naive approach that feeds the wclock on every tick, e.g. each millisecond, by using
ceu_input(CEU_INPUT__WCLOCK, &dt);
Instead, I would like Céu to let me know when the next wclock tick is actually required. In the old version 1.x of Céu this has been done through a global variable assignment, I think it was something like WCLOCK_NEXT. The latter has been updated by Céu with the next point in time to wake up. Now, in Céu 3.x, there is an additional callback CEU_CALLBACK_WCLOCK_DT introduced which I guess is used for this purpose. However, so far I did not understand how to use it correctly.
Could you point to a basic example which illustrates the concept? What exactly do I have to return in ceu_callback_ret.num? Is it the elapsed system time since the last callback invocation? How does Céu gets triggered once the required delta time has been elapsed?