Oh absolutely! Adam Dunkels' work is legendary. It's kind of poetic that Protothreads achieved stackless concurrency via C preprocessor macros and Duff's device tricks, and now years later, C++20 finally baked that exact same "state machine via switch-case" logic directly into the compiler. Same spirit, just less macro magic! :)
Simon Tatham and Tom Duff too.
https://www.chiark.greenend.org.uk/~sgtatham/coroutines.html
The legendary "Coroutines in C" article!
Thanks for the reference—I learned a lot from his work. His use of macros to hide the switch statement is basically the spiritual ancestor of co_await. It is wild to think that C++20 essentially standardized that exact pattern, just moving the "state machine generation" from the preprocessor hacks to the compiler itself.