a lot of re-import warnings have cropped up. While I appreciate
their studiousness on this, the problem is that removing some
of these exports in the API crate could mean that future users
who want access to some API features that aren't used in this
configuration are now unaccessible.
I think it's not a huge problem at the moment, just spam-cleaning
the warnings because there are too many to deal with carefully
at the moment.
- make the "base" field no longer public. It is accessible, but only
through an `unsafe` method, because, it is unsafe.
- add accessors to offest/mask fields. Because, it's not at all
unsafe to access these, and it can be useful for bit-ops that are
not part of the generic set of UTRA.
- add Arc to AtomicCSR, and require `std` for AtomicCSR types.
This should not break anything, I checked inside @foundation-devices
keyOS and they don't seem to be using AtomicCSR anywhere.
The Arc makes it a bit safer to clone the AtomicCSR base pointer
and share it between threads, but it will have an impact on performance.
The USB stack (which requires AtomicCSR) was regression testing and the
impact seems minimal.
Recall that the main purpose of AtomicCSR is to provide a CSR accessor
that does not require a mutable reference to the base object. This
can make certain Rust idioms a bit cleaner. We wrap the base accessor
in Arc+Atomic to try and improve the safety of throwing the borrow
checker under the bus, but it's still not perfect because hardware
mutable state can have side-effects within hardware itself that cannot
be modeled or checked by Rust's borrow checker.
For some unknown reason, just adding a second bulk endpoint descriptor makes enumeration
fail on essentially all operating systems.
Adding three endpoints is no issue though, but since we want to avoid wasting resources around
here, writing 0x42 at the end of the last bulk endpoint... fixes everything.
Tested under Linux, Windows, OpenBSD, FreeBSD.
