Frankly, I'm unlikely to write much documentation for this part. I'm also only providing a Clang _Makefile_ for now. If you're using gcc, have a go at putting your own _Makefile_ together, referencing the previous parts.
This part simply builds on the work we've done so far, and delivers a new Breakout codebase with:
* Gameplay running in the foreground on the main CPU core 0
* Graphics updated in the background on CPU core 1
* Looped 8-bit music playing in the background on CPU core 2
* Bluetooth communications managed in the background on CPU core 3
I've taken the opportunity to organise the code a little better and so you'll see some changes to the _Makefile_, and a new directory structure in place. Tidy codebase = tidy mind!
Important takeaway
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As you read through this code, you'll maybe notice that a very different style has emerged. Multi-processing adds a dimension of complexity when coding and requires a total mindset shift.
There's a lot more signalling/semaphores, so the cores can be sure they're doing the right thing at the right time.
You're no longer "dry-running" a single, sequential thread. You're having to spot the potential for bugs/unexpected behaviour from the interplay of four concurrent threads!