third_party/rust_crates/vendor/bitfield/README.md

rust-bitfield
=============

This crate provides macros to generate bitfield-like struct.

This a complete rewrite of the `bitfield` crate.
You can find the previous version in the [rust-bitfield-legacy](https://github.com/dzamlo/rust-bitfield-legacy) repository. This version works on the stable version of rustc and use a different syntax with different possibility.


## Example

An IPv4 header could be described like that:

```rust
bitfield!{
    struct IpV4Header(MSB0 [u8]);
    u32;
    get_version, _: 3, 0;
    get_ihl, _: 7, 4;
    get_dscp, _: 13, 8;
    get_ecn, _: 15, 14;
    get_total_length, _: 31, 16;
    get_identification, _: 47, 31;
    get_df, _: 49;
    get_mf, _: 50;
    get_fragment_offset, _: 63, 51;
    get_time_to_live, _: 71, 64;
    get_protocol, _: 79, 72;
    get_header_checksum, _: 95, 79;
    get_source_address, _: 127, 96;
    get_destination_address, _: 159, 128;
}
```

In this example, all the fields are read-only, the _ as setter name signals to skip the setter method.
The range at the end (e.g. 3, 0) defines the bit range where the information is encoded.

## Documentation

The documentation of the released version is available on [doc.rs](https://docs.rs/bitfield).


## License

Licensed under either of

 * Apache License, Version 2.0, ([LICENSE-APACHE](LICENSE-APACHE) or http://www.apache.org/licenses/LICENSE-2.0)
 * MIT license ([LICENSE-MIT](LICENSE-MIT) or http://opensource.org/licenses/MIT)

at your option.

### Contribution

Unless you explicitly state otherwise, any contribution intentionally
submitted for inclusion in the work by you, as defined in the Apache-2.0
license, shall be dual licensed as above, without any additional terms or
conditions.