Clang format

[2bndy5]

This PR is designed to enforce uniform code style using clang-format. The style rules that clang-format adheres to are defined in the .clang-format files.

While modifying the CI workflows to check code format, I added a new action that will report compile size changes when the PR is open or re-opened. The reports come in the form of thread comments (see below), and they only focus on Arduino Nano, ATTinyx5, and Arduino MKR Zero. This solves #802

There are 2 .clang-format files:

1. The .clang-format at root of the repo specifies the style rules used for all C/C++ files in the repo except for the BCM2xxx lib source code (in utility/RPi) and the examples directory (& its sub-directories) - it is used for Linux and Pico SDK examples.
2. The .clang-format located in examples directory specifies the style rules for all Arduino/PlatformIO examples.

Using the cpp-linter-action

For now I have the action setup to check all source code in the repo. This could be changed to only check the the event's diff for code style violations. This decision is entirely dependent on preference and checking only the diff will yield slightly faster CI runs (like 2 or 3 seconds faster).

• Linux CI workflow will not check Arduino/PlatformIO examples.
  • Please note that the utility/RPi/bcm2835.* files are ignored since that code is not maintained here (only distributed from here).
• Arduino/PlatformIO CI workflows will only check the examples' code (not the lib's code).
  • Please note that the examples/old_backups directory is ignored by the action (mainly because those examples aren't compiled in the CI workflows).

As of right now, the action is configured to use clang-format v12 since that was the latest stable version available via apt and LLVM releases at the initial creation of this branch. Note that by default sudo apt install clang-format installs clang-format v10 (use sudo apt install clang-format-12).

For those of you using VSCode, there is a handy extension that formats source code using the locally installed clang-format; I used this extension to make the most of changes in this PR. There are other officially endorsed IDE integrations which are named in the LLVM docs.

Going Forward

I plan to create a repo for the nRF24 org (called .github - see github docs about org profiles)

• This new repo will be the home for any files that are not specific to any particular code in the org's repos/libs, namely CONTRIBUTING.md.

• I will begin writing up a code style guideline there, so that the style rules defined in the .clang-format files are explicitly explained.

• Potentially, the .github repo could also contain re-usable CI workflows/actions. This is more of a long-term goal though.

  In researching this further I found that only workflows that don't use a job matrix can call reusable workflows. This means that only the docs CI could be made into a reusable workflow from the .github repo.

Lastly I found and fixed a dead link in CONTRIBUTING.md to the Arduino example style guide.

[github-actions]

Memory usage change @ 51da30e

Board	flash	%	RAM for global variables	%
ATTinyCore:avr:attinyx5	0 - 0	0.0 - 0.0	0 - 0	0.0 - 0.0
arduino:avr:nano	0 - 0	0.0 - 0.0	0 - 0	0.0 - 0.0
arduino:samd:mkrzero	🔺 0 - +4	0.0 - 0.0	0 - 0	0.0 - 0.0

Click for full report table

Board	examples/rf24_ATTiny/rf24ping85 flash	%	examples/rf24_ATTiny/rf24ping85 RAM for global variables	%	examples/rf24_ATTiny/timingSearch3pin flash	%	examples/rf24_ATTiny/timingSearch3pin RAM for global variables	%	examples/GettingStarted flash	%	examples/GettingStarted RAM for global variables	%	examples/AcknowledgementPayloads flash	%	examples/AcknowledgementPayloads RAM for global variables	%	examples/ManualAcknowledgements flash	%	examples/ManualAcknowledgements RAM for global variables	%	examples/StreamingData flash	%	examples/StreamingData RAM for global variables	%	examples/MulticeiverDemo flash	%	examples/MulticeiverDemo RAM for global variables	%	examples/InterruptConfigure flash	%	examples/InterruptConfigure RAM for global variables	%	examples/scanner flash	%	examples/scanner RAM for global variables	%
ATTinyCore:avr:attinyx5	0	0.0	0	0.0	0	0.0	0	0.0
arduino:avr:nano									0	0.0	0	0.0	0	0.0	0	0.0	0	0.0	0	0.0	0	0.0	0	0.0	0	0.0	0	0.0	0	0.0	0	0.0	0	0.0	0	0.0
arduino:samd:mkrzero									0	0.0	0	0.0	0	0.0	0	0.0	0	0.0	0	0.0	0	0.0	0	0.0	0	0.0	0	0.0	0	0.0	0	0.0	4	0.0	0	0.0

Click for full report CSV

Board,examples/rf24_ATTiny/rf24ping85<br>flash,%,examples/rf24_ATTiny/rf24ping85<br>RAM for global variables,%,examples/rf24_ATTiny/timingSearch3pin<br>flash,%,examples/rf24_ATTiny/timingSearch3pin<br>RAM for global variables,%,examples/GettingStarted<br>flash,%,examples/GettingStarted<br>RAM for global variables,%,examples/AcknowledgementPayloads<br>flash,%,examples/AcknowledgementPayloads<br>RAM for global variables,%,examples/ManualAcknowledgements<br>flash,%,examples/ManualAcknowledgements<br>RAM for global variables,%,examples/StreamingData<br>flash,%,examples/StreamingData<br>RAM for global variables,%,examples/MulticeiverDemo<br>flash,%,examples/MulticeiverDemo<br>RAM for global variables,%,examples/InterruptConfigure<br>flash,%,examples/InterruptConfigure<br>RAM for global variables,%,examples/scanner<br>flash,%,examples/scanner<br>RAM for global variables,%
ATTinyCore:avr:attinyx5,0,0.0,0,0.0,0,0.0,0,0.0
arduino:avr:nano,,,,,,,,,0,0.0,0,0.0,0,0.0,0,0.0,0,0.0,0,0.0,0,0.0,0,0.0,0,0.0,0,0.0,0,0.0,0,0.0,0,0.0,0,0.0
arduino:samd:mkrzero,,,,,,,,,0,0.0,0,0.0,0,0.0,0,0.0,0,0.0,0,0.0,0,0.0,0,0.0,0,0.0,0,0.0,0,0.0,0,0.0,4,0.0,0,0.0

[TMRh20]

Quite a bit of changes to review here, but I guess most if it is formatting changes. Looks good from what I can see so far...

[2bndy5]

Yeah, its all white space changes and some CI upgrades. I just wanted your sign off on the style because these changes will validate a consistent code style going forward (clang-format can be rather picky).

@Avamander I know we haven't heard much from you lately, but if you wanted to review before merging, let me know. I mention this because you've expressed significant interest about code style in the past.

Once this is merged, I'll open similar PRs for the other nRF24 repos...

[Avamander]

Yeah, I've been a bit busy. These changes look good.