FFI support

Question

FFI support

nucflash opened this issue 8 years ago · 8 comments

Hi, I need FFI support in ports/esp32 because I want to use the micropython-schedule package. I tried to build commit 292816a but it seems that the FFI library, which is an external dependency for ports/unix is not linked in ports/esp32. Can you confirm if this is the case, and if it is if there is a plan to support it in the future?

Answer 1 · 2017-11-29T06:04:04.000Z

It appears the ffi module in the Unix port is a "Foreign Function Interface" library, correct?

And I'm assuming you mean this micropython-schedule library?

Answer 2 · 2017-11-29T07:41:25.000Z

Yes and yes. In my understanding, micropython-schedule is internally using functools for building function partials which depends on FFI functionality.

Answer 3 · 2017-11-29T19:37:45.000Z

Well, the functools in micropython/micropython-lib doesn't appear to need FFI.

Answer 4 · 2017-11-29T19:59:21.000Z

You're right, my bad. Below is the error I'm getting. It seems that the time module is choking. Have you seen this before?

import schedule
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
  File "/lib/schedule/__init__.py", line 39, in <module>
  File "/lib/time.py", line 4, in <module>
ImportError: no module named 'ffi'

Answer 5 · 2017-11-29T22:34:34.000Z

The time module in micropython/micropython-lib will only work on the Unix port, because it's using FFI to access libc for the time functions.

There's a built-in µPy time module in the ESP32 firmware. It appears that that time module will probably work with the micropython-schedule; seems to have all the necessary functions. Should just be a matter of deleting time.py from your ESP32 filesystem.

Answer 6 · 2017-11-29T23:06:40.000Z

@dpgeorge Why do we have a "pure" Python time library that will only work on Unix (i.e. not at all pure)? Why not a built-in C time library?

Answer 7 · 2017-11-30T04:32:43.000Z

Why do we have a "pure" Python time library that will only work on Unix

Good question! The history of the micropython-lib repo is that it was intended to be individual add-on modules for the unix port of uPy. But over time some of the modules there have been written to target all ports of uPy (eg uasyncio, umqtt), and some other modules might work on any port because they are "pure".

Answer 8 · 2019-01-16T09:04:48.000Z

ffi is not supported on esp32. To get micropython-schedule working on the esp32 would require modifying it to not rely on ffi.