msrtc-rans

Safe public Rust entropy-coder API for msrtc_rans.

This crate provides the high-level entropy coder API, wrapping the raw rANS primitives from msrtc-rans-core with PMF validation, CDF table construction, bypass coding, and distribution descriptors.

Status

Feature	Status
`EntropyEncoder`	✅ Implemented
`EntropyDecoder`	✅ Implemented
PMF validation	✅ Implemented
CDF table construction	✅ Implemented
Bypass coding (variable-width)	✅ Implemented
Entropy differential court	✅ Sealed (6/6 cases)

The full entropy encode/decode pipeline (PMF → CDF → bypass) has been verified byte-for-byte against the pinned Microsoft C++ oracle.

Features

#![forbid(unsafe_code)] — pure safe Rust
Both RansByte (u8) and Rans64 (u32) variant support
PMF validation: rejects empty tables, invalid dimensions, zero frequencies
Bypass coding for out-of-range values with configurable bypass bits
Mixed in-range and bypass value streams
Comprehensive error handling via EntropyError enum
Re-exports all msrtc-rans-core types and traits

Usage

use msrtc_rans::entropy::EntropyEncoder;
use msrtc_rans_core::RansByte;

let mut encoder = EntropyEncoder::<RansByte>::new();

let pmf_lengths = vec![2u32];
let pmf_offsets = vec![0u32];
let pmf_table = vec![1u32, 3u32];  // frequencies
let symbol_bits = 16;
let bypass_bits = 4;

encoder.initialize(&pmf_lengths, &pmf_offsets, &pmf_table, symbol_bits, bypass_bits)
    .expect("valid PMF");

let values = vec![-2i32, 1i32, 0i32, 1i32];
let encoded = encoder.encode(&values).expect("encode");

Repository

Full project: github.com/infinityabundance/msrtc-rans-rs

License