Gzip decompression in 250 lines of Rust
3 days ago
- #rust
- #gzip
- #compression
- The author wrote a gzip decompressor in Rust to understand compression better, resulting in a 250-line implementation.
- Gzip is widely used in web traffic, log files, and archives, making it a fundamental tool in software ecosystems.
- The implementation focuses on core DEFLATE algorithm concepts, ignoring checksums and less-used features for simplicity.
- Gzip files start with a magic number (0x1F 0x8B) and metadata, followed by compressed data in DEFLATE format.
- DEFLATE blocks can be uncompressed (type 0), use fixed Huffman codes (type 1), or dynamic Huffman codes (type 2).
- Huffman coding optimizes compression by assigning shorter codes to more frequent symbols.
- Dynamic Huffman blocks include custom Huffman tables, encoded themselves with Huffman codes for efficiency.
- LZ77 back-references enhance compression by replacing repeated sequences with references to previous data.
- The decompressor maintains a 32KB sliding window for back-references, enabling efficient data reconstruction.
- The author emphasizes the value of starting with a simple, working implementation before optimizing.