Crate endian_codec

This crate helps serialize types as bytes and deserialize from bytes with a special byte order. This crate can be used in no_std environment and has no external dependencies.

If you are looking for a small universal binary (de)serializer that works with serde, look at bincode.

Main features:

• A clean way to convert structures to endians and back
• Derive
• no_std and no external dependencies

Examples

use endian_codec::{PackedSize, EncodeLE, DecodeLE};
// If you look at this structure without checking the documentation, you know it works with
// little-endian notation
#[derive(Debug, PartialEq, Eq, PackedSize, EncodeLE, DecodeLE)]
struct Version {
  major: u16,
  minor: u16,
  patch: u16
}

let mut buf = [0; Version::PACKED_LEN]; // From PackedSize
let test = Version { major: 0, minor: 21, patch: 37 };
// if you work with big- and little-endians, you will not mix them accidentally
test.encode_as_le_bytes(&mut buf);
let test_from_b = Version::decode_from_le_bytes(&buf);
assert_eq!(test, test_from_b);

There can be also a situation when you are forced to work with mixed-endians in one struct.

use endian_codec::{PackedSize, EncodeME};
// even if you only use derive EncodeME, you also need to have required traits in the scope.
use endian_codec::{EncodeLE, EncodeBE}; // for #[endian = "le/be"]

#[derive(PackedSize, EncodeME)]
// You work with a very old system and there are mixed-endians
// There will be only one format "le" or "little" in the next minor version.
struct Request {
  #[endian = "le"]
  cmd: u16,
  #[endian = "little"] // or #[endian = "le"]
  value: i64,
  #[endian = "big"] // or #[endian = "be"]
  timestamp: i128,
}

let mut buf = [0; Request::PACKED_LEN];
let req = Request {
  cmd: 0x44,
  value: 74,
  timestamp: 0xFFFF_FFFF_0000_0000,
};
// here we see me (mixed-endian), just look at the struct definition for details
req.encode_as_me_bytes(&mut buf);

Why another crate to handle endians?

• Easy byteorder-encoding structs with multiple fields and consistent encoding
• Learning how to create custom derives
• Making a cleaner API

There are a few other crates that deal with endians:

• byteorder - Library for reading/writing numbers in big-endian and little-endian.
• bytes - Buf and BufMut traits that have methods to put and get primitives in the desired endian format.
• simple_endian - Instead of providing functions that convert - create types that store variables in the desired endian format.
• struct_deser - Inspiration for this crate - but in a more clean and rusty way.

Traits

DecodeBE	Decode from bytes stored as a big-endian.
DecodeLE	Decode from bytes stored as a little-endian.
DecodeME	Decode from bytes stored as a mixed-endian.
EncodeBE	Encoded as big-endian bytes.
EncodeLE	Encoded as little-endian bytes.
EncodeME	Encode using mixed-endian bytes.
PackedSize	Represents size of a struct as packed bytes.

Derive Macros

DecodeBE
DecodeLE
DecodeME
EncodeBE
EncodeLE
EncodeME
PackedSize