Hmm. You raise a good point. I've been doing a bit of C FFI on std-rust applications, but hadn't thought to apply this to embedded much. I have wrapped CMSIS-DSP (ARM-official DSP toolkit; filters etc) with Rust embedded, and it works out well! Increases compile times, but worth it. Perhaps we should apply this approach more broadly.
One problem: It's tedious going from the pointer-level API bindgen gives you to a high-level rust API that has references, arrays etc. In that you have to do some boilerplate for each bit of functionality you want. Not a big deal for a specific application, but not ideal if making a general library. And C libs tend to be sloppy with integer types, which works, but is not really idiomatic for rust. Maybe that could be automated with codegen or proc macros?
I believe the ESP-IDF rust lib is mostly FFI (?); maybe that's a good example. We've been re-inventing the wheel re STM-32 and Nordic support.
One problem: It's tedious going from the pointer-level API bindgen gives you to a high-level rust API that has references, arrays etc. In that you have to do some boilerplate for each bit of functionality you want. Not a big deal for a specific application, but not ideal if making a general library. And C libs tend to be sloppy with integer types, which works, but is not really idiomatic for rust. Maybe that could be automated with codegen or proc macros?
I believe the ESP-IDF rust lib is mostly FFI (?); maybe that's a good example. We've been re-inventing the wheel re STM-32 and Nordic support.