djvu-zp

Pure-Rust clean-room implementation of the ZP adaptive binary arithmetic coder specified in the DjVu v3 specification.

ZP is the entropy coder underlying every codec in a DjVu file: BZZ (text-chunk compression), JB2 (bilevel image), and IW44 (wavelet color/grey image).

This crate exposes the coder primitives so codec implementations and other downstream consumers (e.g. format-conformance tools, fuzz harnesses) can share one well-tested implementation.

Status

Extracted from the djvu-rs umbrella crate as part of issue #229. The decoder is the same code shipped in djvu-rs ≥ 0.14, vetted by the project's full corpus + property + fuzz suite.

Usage

Decoder (no-std capable, no allocations)

use djvu_zp::ZpDecoder;

let compressed: &[u8] = &[0x00, 0x00];
let mut dec = ZpDecoder::new(compressed)?;
let mut ctx = 0u8;
let _bit = dec.decode_bit(&mut ctx);
# Ok::<(), djvu_zp::ZpError>(())

Encoder (requires std, default-on)

use djvu_zp::encoder::ZpEncoder;

let mut enc = ZpEncoder::new();
let mut ctx = 0u8;
enc.encode_bit(&mut ctx, true);
let bytes: Vec<u8> = enc.finish();

Features

License

MIT — see the upstream djvu-rs repository.