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# bzipper
[`bzipper`](https://crates.io/crates/bzipper) is a binary (de)serialiser for the Rust language.
Contrary to [Serde](https://crates.io/crates/serde/)/[Bincode](https://crates.io/crates/bincode/), the goal of bzipper is to serialise with a known size constraint.
Therefore, this crate may be more suited for networking or other cases where a fixed-sized buffer is needed.
Keep in mind that this project is still work-in-progress.
This crate is compatible with `no_std`.
## Data model
Most primitive types serialise losslessly, with the exception being `usize` and `isize`.
These serialise as `u32` and `i32`, respectively, for portability reasons.
Unsized types, such as `str` and slices, are not supported.
Instead, arrays should be used.
For strings, the `FixedString` type is also provided.
## Usage
This crate revolves around the `Serialise` and `Deserialise` traits, both of which are commonly used in conjunction with streams (more specifically, s-streams and d-streams).
Many core types come implemented with bzipper, including primitives as well as some standard library types such as `Option` and `Result`.
It is recommended in most cases to just derive these traits for custom types (enumerations and structures only).
Here, each field is chained in declaration order:
```rs
use bzipper::{Deserialise, Serialise};
#[derive(Debug, Deserialise, PartialEq, Serialise)]
struct IoRegister {
addr: u32,
value: u16,
}
let mut buf: [u8; IoRegister::SERIALISED_SIZE] = Default::default();
IoRegister { addr: 0x04000000, value: 0x0402 }.serialise(&mut buf).unwrap();
assert_eq!(buf, [0x04, 0x00, 0x00, 0x00, 0x04, 0x02]);
assert_eq!(IoRegister::deserialise(&buf).unwrap(), IoRegister { addr: 0x04000000, value: 0x0402 });
```
### Serialisation
To serialise an object implementing `Serialise`, simply allocate a buffer for the serialisation.
The required size of any given serialisation is specified by the `SERIALISED_SIZE` constant:
```rs
use bzipper::Serialise;
let mut buf: [u8; char::SERIALISED_SIZE] = Default::default();
'Ж'.serialise(&mut buf).unwrap();
assert_eq!(buf, [0x00, 0x00, 0x04, 0x16]);
```
The only special requirement of the `serialise` method is that the provided byte slice has an element count of exactly `SERIALISED_SIZE`.
We can also use streams to *chain* multiple elements together.
```rs
use bzipper::Serialise;
let mut buf: [u8; char::SERIALISED_SIZE * 5] = Default::default();
let mut stream = bzipper::Sstream::new(&mut buf);
stream.append(&'ل');
stream.append(&'ا');
stream.append(&'م');
stream.append(&'د');
stream.append(&'ا');
assert_eq!(buf, [0x00, 0x00, 0x06, 0x44, 0x00, 0x00, 0x06, 0x27, 0x00, 0x00, 0x06, 0x45, 0x00, 0x00, 0x06, 0x2F, 0x00, 0x00, 0x06, 0x27]);
```
When serialising primitives, the resulting byte stream is in big endian (a.k.a. network endian).
It is recommended for implementors to adhere to this convention as well.
### Deserialisation
Deserialisation works with an almost identical syntax to serialisation.
To deserialise a buffer, simply call the `deserialise` method:
```rs
use bzipper::Deserialise;
let data = [0x45, 0x54];
assert_eq!(<u16>::deserialise(&data).unwrap(), 0x4554);
```
Just like with serialisations, the `Dstream` can be used to deserialise chained elements:
```rs
use bzipper::Deserialise;
let data = [0x45, 0x54];
let stream = bzipper::Dstream::new(&data);
assert_eq!(stream.take::<u8>().unwrap(), 0x45);
assert_eq!(stream.take::<u8>().unwrap(), 0x54);
```
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