oxiarc-deflate

Pure Rust implementation of the DEFLATE compression algorithm (RFC 1951).

Overview

DEFLATE is the compression algorithm used in:

• ZIP archives
• GZIP compressed files
• PNG images
• HTTP compression
• Many other formats

This crate provides both compression and decompression with no external dependencies.

Features

• Pure Rust - No C bindings or unsafe code
• Full RFC 1951 compliance - All block types supported
• Compression levels 0-9 - From stored to maximum compression
• Streaming API - Process data in chunks
• One-shot API - Convenient functions for simple cases

Quick Start

use oxiarc_deflate::{deflate, inflate};

// Compress data
let original = b"Hello, World! Hello, World! Hello, World!";
let compressed = deflate(original, 6)?;  // Level 6 (default)

// Decompress data
let decompressed = inflate(&compressed)?;
assert_eq!(&decompressed, original);

Compression Levels

API

High-Level Functions

// Compress with specified level
let compressed = deflate(data, level)?;

// Decompress
let decompressed = inflate(&compressed)?;

Streaming API

use oxiarc_deflate::{Deflater, Inflater};

// Streaming compression
let mut deflater = Deflater::new(6);
let compressed = deflater.compress_all(data)?;

// Streaming decompression
let mut inflater = Inflater::new();
loop {
    let (consumed, produced, status) = inflater.decompress(input, output)?;
    // Handle status...
}

LZ77 Encoder

use oxiarc_deflate::{Lz77Encoder, Lz77Token};

let mut encoder = Lz77Encoder::new(6);
for token in encoder.encode(data) {
    match token {
        Lz77Token::Literal(byte) => { /* literal byte */ }
        Lz77Token::Match { length, distance } => { /* back-reference */ }
    }
}

Huffman Trees

use oxiarc_deflate::{HuffmanTree, HuffmanBuilder};

// Build tree from code lengths
let lengths = [3, 3, 3, 3, 3, 2, 4, 4];
let tree = HuffmanTree::from_lengths(&lengths)?;

// Decode symbols
let symbol = tree.decode(&mut bit_reader)?;

Algorithm Details

DEFLATE Structure

+------------------+
| Block Header     | (3 bits: BFINAL + BTYPE)
+------------------+
| Block Data       | (varies by type)
+------------------+
| ... more blocks  |
+------------------+

Block Types

LZ77 Parameters

• Window size: 32768 bytes (32KB)
• Match length: 3-258 bytes
• Match distance: 1-32768 bytes
• Minimum match: 3 bytes

Huffman Alphabets

Literal/Length (286 symbols):

• 0-255: Literal bytes
• 256: End of block
• 257-285: Length codes (3-258)

Distance (30 symbols):

• 0-29: Distance codes (1-32768)

Fixed Huffman Code Lengths

Modules

Performance

Compression ratios on typical data (Calgary Corpus):

References

• RFC 1951 - DEFLATE Compressed Data Format Specification
• An Explanation of the Deflate Algorithm

License

MIT OR Apache-2.0