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# C-Compatible Bit Ordering
This type alias attempts to match the bitfield ordering used by GCC on your
target. The C standard permits ordering of single-bit bitfields in a structure
to be implementation-defined, and GCC has been observed to use Lsb0-ordering on
little-endian processors and Msb0-ordering on big-endian processors.
This has two important caveats:
- ordering of bits in an element is **completely** independent of the ordering
of constituent bytes in memory. These have nothing to do with each other in
any way. See [the user guide][0] for more information on memory
representation.
- GCC wide bitfields on big-endian targets behave as `<T, Lsb0>` bit-slices
using the `_be` variants of `BitField` accessors. They do not match `Msb0`
bit-wise ordering.
This type is provided solely as a convenience for narrow use cases that *may*
match GCC’s `std::bitset<N>`. It makes no guarantee about what C compilers for
your target actually do, and you will need to do your own investigation if you
are exchanging a single buffer across FFI in this manner.
[0]: https://bitvecto-rs.github.io/bitvec/memory-representation
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