zrip

Pure Rust zstd codec. Levels -7 through 4 (Fast and DFast strategies). Optimized for encode throughput in transfer pipelines that need standard zstd frames at high speed.

zrip = "0.1"

Why zrip

Fastest pure-Rust zstd encoder available. 66% faster encode than structured-zstd at L3, 20% faster at L-1. Faster decode than ruzstd at all levels and faster decode than structured-zstd at L3 (34%) and L-1 (12%).

Negative levels (-7..-1) for high-throughput pipelines. Most zstd libraries only expose levels 1+.

no_std + alloc. Works in embedded and kernel contexts with the alloc feature; frame requires std.

Dictionary compression. COVER and FastCOVER training built in for small-message workloads (log lines, JSON records, RPC payloads).

Performance

Geomean across a 16-file Silesia + misc corpus on Intel i7-8700B (x86_64, SSE2/AVX2), performance governor, turbo off. Ratio is original / compressed; higher is better.

zrip vs C zstd

Encode is 40-50% of C zstd at negative levels, closing to ~85% at L3/L4. Decode is 45-75% of C zstd. Ratio is within 2% at negative levels, widening to ~13% at L4. The gap is pure Rust vs hand-tuned C with SIMD assembly in its hot paths.

API

// One-shot (allocating)
let compressed = zrip::compress(input, 1)?;
let original   = zrip::decompress(&compressed)?;

// One-shot into caller buffer
let n = zrip::compress_into(input, &mut output_buf, 1)?;
zrip::decompress_into(&compressed, &mut output_vec)?;

// Reusable context (amortizes table allocation across calls)
let mut ctx = zrip::CompressContext::new(1)?;
let compressed = ctx.compress(input)?;

let mut dec = zrip::DecompressContext::new();
let original = dec.decompress(&compressed)?;

Streaming

use std::io::Write;

let mut enc = zrip::FrameEncoder::new(Vec::new(), 1)?;
enc.write_all(b"hello")?;
enc.write_all(b" world")?;
let compressed = enc.finish()?;

use std::io::Read;
let mut dec = zrip::FrameDecoder::new(&compressed[..]);
let mut out = String::new();
dec.read_to_string(&mut out)?;

Dictionary compression

let dict = zrip::Dictionary::from_bytes(&dict_bytes)?;
let compressed = zrip::compress_with_dict(input, 1, &dict)?;
let original   = zrip::decompress_with_dict(&compressed, &dict)?;

Features

Safety

All compression and decompression logic is #![forbid(unsafe_code)]. Unsafe is confined to two places:

• unchecked.rs modules inside bitstream/, decode/, encode/, fse/, huffman/: small unsafe fn wrappers (get_unchecked, read_unaligned) with debug_assert! guards, called only after block-level bounds checks.
• simd/: intrinsics and raw pointer arithmetic for wildcopy, copy-match, and the SIMD sequence decoder. Dispatch happens at block boundaries, not per-sequence.

Levels

Level 0 is not valid; use 1 for the standard fast level. All levels match C zstd's ZSTD_defaultCParameters table.