Refactored top_gen.py

[HU90m]

I was struggling to follow along with what top_gen.py was doing, so I refactored it a little as I went.

The commits:

1. I added types, made the configuration immutable, and simplified the logic a little.
2. I split the two stages of top_gen.py, configuration parsing and file generation, into their own files.

Note, the templates and generated output remain untouched to show this refactor doesn't change functionality.

[AlexJones0]

Thanks for all the work on this, it's looking good! I've left some comments on parts that might be refactored further to increase readability. Feel free to not change stuff if you disagree.

I'm happy with this, but I'd recommend waiting for @marnovandermaas to review to ensure that the existing functionality that was originally created is retained with this PR.

[marnovandermaas]

Wow, this is a massive rewrite. From an initial read-through it looks better to me than the original. When you run this new top generator, does it generate identical SystemVerilog for the pinmux?

[AlexJones0]

When you run this new top generator, does it generate identical SystemVerilog for the pinmux?

As far as I can tell from running it locally, running this refactor results in no change to any of the generated output. The generated RTL, docs etc. are the exact same.

[HU90m]

Wow, this is a massive rewrite. From an initial read-through it looks better to me than the original. When you run this new top generator, does it generate identical SystemVerilog for the pinmux?

Yep, I put a bit of work into making sure it generates exactly the same output

[HU90m]

@marnovandermaas happy for me to merge this?

[marnovandermaas]

Approving since RTL matches according to Hugo.