ax-codec

Binary codec for Rust focused on predictable runtime, minimal allocation, and zero-copy decoding.

• no_std compatible
• Zero-copy decode via View<'a>
• Derive macros for codec traits
• Varint encoding support
• Optional SIMD decode fast-path
• Decode limits and validation
• Tokio codec integration

---

Installation

[dependencies]
ax-codec = { version = "0.1", features = ["std"] }
ax-codec-derive = "0.1"
ax-codec-core = "0.1"

---

Quick Start

use ax_codec::{
    Decode,
    Encode,
    VecWriter,
    SliceReader,
};

use ax_codec_derive::{
    Decode,
    Encode,
};

#[derive(Encode, Decode)]
struct Packet {
    id: u32,
    payload: Vec<u8>,
}

let packet = Packet {
    id: 42,
    payload: vec![1, 2, 3],
};

let mut writer = VecWriter::new();

packet.encode(&mut writer).unwrap();

let bytes = writer.into_vec();

let decoded =
    Packet::decode(
        &mut SliceReader::new(&bytes)
    ).unwrap();

assert_eq!(decoded.id, 42);

---

Zero-copy View

use ax_codec::{
    Encode,
    Decode,
    View,
    VecWriter,
};

use ax_codec_derive::{
    Encode,
    Decode,
    View,
};

#[derive(Encode, Decode, View)]
struct Message<'a> {
    id: u32,
    text: &'a str,
}

let msg = Message {
    id: 1,
    text: "hello",
};

let mut writer = VecWriter::new();

msg.encode(&mut writer).unwrap();

let bytes = writer.into_vec();

let decoded = Message::view(&bytes).unwrap();

assert_eq!(decoded.text, "hello");

---

Validation

use ax_codec::{
    Encode,
    Validate,
    VecWriter,
    SliceReader,
};

let mut writer = VecWriter::new();

packet.encode(&mut writer).unwrap();

let mut reader =
    SliceReader::new(writer.as_slice());

Packet::validate(&mut reader).unwrap();

Validate payloads without allocating decoded values.

---

Tokio Integration

use ax_codec_net::codec::ax_codec;

use tokio_util::codec::Framed;

let framed =
    Framed::new(
        socket,
        ax_codec::<Packet>::new()
    );

---

Workspace Crates

Crate	Description
ax-codec-core	Core codec traits and primitives
ax-codec-derive	Derive macros
ax-codec-bytes	Buffer pooling and bytes integration
ax-codec-net	Tokio and network utilities

---

Core Traits

Trait	Description
Encode	Serialize values
Decode	Owned deserialization
View<'a>	Zero-copy deserialization
Validate	Wire-format validation

---

Features

• no_std + alloc
• Borrowed decoding
• SIMD varint decode
• CRC32 checked decode
• Versioned decode support
• Decode resource limits

---

Testing

cargo test --all-features --workspace

no_std

cargo test \
  --no-default-features \
  --features alloc \
  -p ax-codec-core

---

Benchmarks

cargo bench --all-features -p ax-codec-core

---

Fuzzing

cargo install cargo-fuzz

cargo fuzz run fuzz_varint

cargo fuzz run fuzz_struct_decode

---

Links

• ax-codec
• ax-codec-core
• ax-codec-derive
• ax-codec-bytes
• ax-codec-net

---

License

MIT