varing 0.13.0

Protobuf's varint encoding/decoding for LEB128 friendly types with full const context operations supports.

Installation

[dependencies]
varing = "0.13"

no_std is supported by disabling the default std feature:

[dependencies]
varing = { version = "0.13", default-features = false }

Quick Start

Encode and decode primitive integers as varints:

use varing::Varint;

// Encode
let mut buf = [0u8; u32::MAX_ENCODED_LEN.get()];
let len = 300u32.encode(&mut buf).unwrap();

// Decode
let (bytes_read, decoded) = u32::decode(&buf).unwrap();
assert_eq!(decoded, 300u32);
assert_eq!(bytes_read, len);

Signed integers use zigzag encoding, so small absolute values stay compact:

use varing::Varint;

let mut buf = [0u8; i64::MAX_ENCODED_LEN.get()];
let len = (-1i64).encode(&mut buf).unwrap();
assert_eq!(len.get(), 1); // -1 encodes to a single byte

Encode/decode sequences:

use varing::{Varint, encode_sequence, decode_sequence, encoded_sequence_len};

let values: Vec<u64> = (0..1024).collect();
let encoded_len = encoded_sequence_len(values.iter());
let mut buf = vec![0; encoded_len];

encode_sequence(values.iter(), &mut buf).unwrap();
let (_bytes_read, decoded) = decode_sequence::<u64, Vec<u64>>(&buf).unwrap();
assert_eq!(decoded, values);

All encoding and decoding functions are available in const context as free functions:

use varing::{encode_u32_varint, decode_u32_varint, encoded_u32_varint_len};

const ENCODED: varing::utils::Buffer<6> = encode_u32_varint(300);

const VALUE: u32 = {
    let Ok((_len, val)) = decode_u32_varint(ENCODED.as_slice()) else { panic!() };
    val
};

assert_eq!(VALUE, 300);
assert_eq!(ENCODED.len(), encoded_u32_varint_len(300).get());

Optional Features

The following feature flags enable varint support for types from third-party crates. Multiple versions of the same crate can be enabled simultaneously.

Testing

• Property-based testing with quickcheck for all types (including optional features).
• Fuzz testing with cargo fuzz for all types.

License

varing is under the terms of both the MIT license and the Apache License (Version 2.0).

See LICENSE-APACHE, LICENSE-MIT for details.

Copyright (c) 2026 Al Liu.