bitintr is the first library that I have publish to crates.io. It offers bitwise manipulation intrinsics for platform specific instructions. It works on stable, but when its compiled with a nightly compiler it uses compiler hooks for some of the intrinsics.
Any feedback and contributions are welcome!
I am using it in my bitwise crate, which provides high-level bitwise manipulation algorithms that work on words and sequences (I hope I can publish a first version of bitwise soon).