Please find attached a proposal draft for bit permutations in <bit>.
The most recent source can also be found at
https://github.com/Eisenwave/cpp-proposals/blob/master/src/bit-deposit-extract-reverse.html

In short, this adds functions for reversing bits and
compressing/expanding them with a mask, like the RBIT ARM, and
PEXT/PDEP x86_64 instructions respectively.

I'd love to hear your thoughts :)