[centimeter]

> If you chuck everything into single struct and pass by pointer, it has same problems as global scope.

Not true. In fact, this refactor is one of the best things you can do to improve an old shitty embedded C codebase. Among other benefits, it allows you to have multiple instances (an arbitrary and easily-adjusted number, in fact) of a system sharing the same memory, reduces the complexity of linker-related BS, and simplifies testing. It's vastly better than relying on horrendous C cross-module scoping rules for sharing.

[jmiskovic]

To me the main problem of global is that any module can mutate and affect any other part. All encapsulation and modularisation is then leaky and you are always on your toes about implementation details in some other part of code. Your approach does not attempt to solve this downside of globals.

I agree that passing in structs is vastly better than communicating over globals. On the other hand, taking existing code base and implementing this state-passing is quite large undertaking that affects all function declarations/implementations. It might be beneficial, but there are often better investments of your time.