Supervisor: create code.py file with sample code

[iayanpahwa]

Addresses Issue #2149

Create a sample code.py file during board flashing with a print hello world program. Tested on CircuitPlayground Express Board.

To-Do's:

1- Add compiler flags to disable this feature on non-express / limited memory boards
2- Error handling when fail to write the file for any reason

[tannewt]

You may be able to save space by creating an empty file for small boards instead of one with basic code.

[iayanpahwa]

@tannewt I'm not sure how to do that, any pointers will be appreciated :)

[iayanpahwa]

@jepler , @dhalbert please share review comments :)

[jepler]

Besides my comments directly on the code, a build failed:

 Build pirkey_m0 for zh_Latn_pinyin took 12.46s and failed
make: Entering directory '/home/runner/work/circuitpython/circuitpython/ports/atmel-samd'
Use make V=1, make V=2 or set BUILD_VERBOSE similarly in your environment to increase build verbosity.

-48 bytes free in flash out of 188160 bytes ( 183.75 kb ).
26000 bytes free in ram for stack out of 32768 bytes ( 32.0 kb ).

Too little flash!!!```

By making this new feature optional, and keeping it disabled for "small" (resource-constrained) boards, this problem can be resolved.

[iayanpahwa]

Thanks @jepler for the review comments and suggestions. I'll push the changes as requested soon.

[tannewt]

@iayanpahwa It would be something like:

#if CIRCUITPY_FULL_BUILD == 0
make_empty_file(&vfs_fat->fatfs, "/code.py");
#else
make_sample_code_file(&vfs_fat->fatfs);
#endif

[iayanpahwa]

@tannewt tried what you suggested, It's breaking builds on some boards. Any idea?

[jepler]

One of the failed builds was arduino_mkr1300 so in ports/atmel-samd you can make BOARD=arduino_mkr1300 to check that your changes have fixed the errors that were detected during CI. (I didn't look at other builds, but most likely they all have the same underlying cause)

[iayanpahwa]

@jepler pushed the fix. Build still failing for pirkey_mo, what do you suggest we do now?

-8 bytes free in flash out of 188160 bytes ( 183.75 kb ).

[jepler]

Now, the error is

Build pirkey_m0 for zh_Latn_pinyin took 11.79s and failed
make: Entering directory '/home/runner/work/circuitpython/circuitpython/ports/atmel-samd'
Use make V=1, make V=2 or set BUILD_VERBOSE similarly in your environment to increase build verbosity.

-8 bytes free in flash out of 188160 bytes ( 183.75 kb ).
26000 bytes free in ram for stack out of 32768 bytes ( 32.0 kb ).

Too little flash!!!

The main option now is to do as @deshipu suggested and do not enable any new feature (including creating a zero-length code.py file) on (CIRCUITPY_FULL_BUILD == 0) boards. So the code would become something like

#if CIRCUITPY_FULL_BUILD!= 0
    FIL fs;
    UINT char_written = 0;
    const byte buffer[] = "print('Hello World!')\n";
    //Create or modify existing code.py file 
    f_open(fatfs, &fs, "/code.py", FA_WRITE | FA_CREATE_ALWAYS);
    f_write(&fs, buffer, sizeof(buffer) - 1, &char_written);
    f_close(&fs);
#endif

specifically without the make_empty_file call. As before you can make BOARD=pirkey_m0 in ports/atmel-samd to check on the result yourself before pushing.

[iayanpahwa]

@jepler guess that's our only option now :)

[iayanpahwa]

@jepler should it be:

#if CIRCUITPY_FULL_BUILD == 0
or
#if CIRCUITPY_FULL_BUILD != 0

? The CIRCUITPY_FULL_BUILD == 0 means build for express boards?

[jepler]

Right, I had it backwards. (edited the original comment so it is correct now, I hope)

[dhalbert]

CIRCUITPY_FULL_BUILD == 1 is for Express boards. I'm confused.

[iayanpahwa]

@dhalbert , @jepler checking on my cpx :)

[iayanpahwa]

@dhalbert you're right. It was

CIRCUITPY_FULL_BUILD == 1

@jepler all checks passed with the pushed fix.

[iayanpahwa]

wow this build passed on my machine :/

[tannewt]

Sit tight. I'm freeing up some space in pIRkey with PR #2328.

[iayanpahwa]

@tannewt seems like a plan :)

[iayanpahwa]

@tannewt it worked.

@jepler , @dhalbert any more changes needed?

[dhalbert]

This looks fine to me now. I reviewed the issue discussion: I didn't realize it was consensus to avoid writing the file completely on non-full builds.

[iayanpahwa]

@dhalbert creation of even empty file idea was dropped because build was failing for pIRKey due to space constraint, Do you think now we have some space for atleast an empty file, since PR #2328 has been merged? If yes maybe we can include that in a different PR.

[dhalbert]

@iayanpahwa I think we could now have this on by default, after the pirkey fix, even for small boards, and for @deshipu and others who need every last byte, it could still be turned off. I think it would be better for the standard boards to be consistent about this.

[iayanpahwa]

@dhalbert sounds good to me. Let me know what do to next.