How to work with std::condition_variable

[fletchjp]

Hi

I am attempting to move some code written for C++11 which uses std::mutex and std::condition_variable. I want to run it on RP2040 hardware.

I have found out how to replace the include of mutex with <CoreMutex.h> and use mutex_t instead of std::mutex.

I would like to do the same for std::condition_variable. I cannot find any information on how to go about this.

What am I missing?

Thanks John

[earlephilhower]

Not really an answer, but some background...

The std::mutex and related are bits of C++ that require OS support. GCC's STL implementation calls to these SDK/OS/etc. defined primitives to build things like std::mutex and std::recursive_mutex from which things like the condition variable can be made.

Right now the Pico SDK doesn't implement these primitives. Since they are really OS-level things (i.e. a mutex_t will not do what you want under FreeRTOS) I can understand the division. There are a few open issues (feature requests) on the Pico-SDK to do an implementation of these for GCC under bare metal and FreeRTOS (ThreadX, you're on your own! 😆 ) but I couldn't find any open PRs related to them yet.

(For reference, I found something doing std::thread infra for GCC and FreeRTOS here. https://github.com/grygorek/FreeRTOS_cpp11 Same idea, we'd need to implement the low level primitives it needs.)