getting the value of mp_hal_ticks_ms() in a natmod

[stef]

i need to have access to a timer in a natmod (to mock time(2)) i saw this: https://github.com/orgs/micropython/discussions/11657 - so i'm not sure if this is a viable option, but i believe calling time.time() from python would give access to such a timer. is there a way to call a python module.function from a natmod? haven't seen that in the examples.

[stef]

i'm also wondering how to access any RNG devices exposed in the hal. i suppose the solution would be similar to the timer access?

[jonnor]

All the functions available to native modules are found in py/dynruntime.h and the function table mp_fun_table_t found in py/nativeglue.h - so that basically defines what is possible and not in terms of interacting with the MicroPython runtime.

To access time.time(), I believe you should be able to use mp_import_from to get a hold of the function, and then use mp_call_function_n_kw to call it.

Another alternative would be to explicitly pass a function from Python that can return the time/tick to your module, and then call that (again with mp_call_function_n_kw).

PS: you may want to use time.tick_ms/ticks_us instead of time.time, if you want a integer

[stef]

that's amazing! i guess this would also work with os.urandom(), only question is does that always expose the hw trng also on espXXxx-es or stm3wb55 platforms?

[jonnor]

Yes calling into Python like that is a rather general mechanism. It would be good to have some code examples of that in the natmod repository...

Regarding the RNG implementation I have no idea. Best to check the code in the respective ports :)

[andrewleech]

I really did think there were some examples but no it seems not! Would certainly be well worth adding.

For reference I load some modules / functions in this natmod example: https://github.com/andrewleech/stm32wb55_mpy_transparent_vcp/blob/1cc8fe25913335d8a5e86f44ee5322f4a0aa0dad/src/stm32wb55_transparent.c#L68

I had submitted an earlier version of this as an example here but the stm licencing made it a bit difficult, hence it's now in its own repo.