Implementations of classic compression algorithms from scratch, using modern C++23.

Sliding-window dictionary compression. Encodes repeated byte sequences as (offset, length, next_char) triples. Configurable window size (default 4096).

Combines LZ77 with Huffman coding. Supports all three block types:

• Type 0 — Stored (uncompressed)
• Type 1 — Fixed Huffman codes
• Type 2 — Dynamic Huffman codes (optimized per block)

Output is compliant with RFC 1951 and can be decompressed by zlib/gzip.

Wraps DEFLATE output in the gzip container format:

• 10-byte header (magic bytes, compression method, flags, MTIME, OS)
• Parses optional header fields (FEXTRA, FNAME, FCOMMENT, FHCRC)
• 8-byte trailer with CRC-32 checksum and original size
• Output is compatible with standard gunzip

Canonical Huffman tree construction from symbol frequencies. Used internally by DEFLATE, also available as a standalone module.

mkdir -p build
g++ -std=c++23 -I src -o build/out \
    src/main.cpp \
    src/lz77/lz77.cpp \
    src/huffman/huffman.cpp \
    src/deflate/bitstream.cpp \
    src/deflate/deflate.cpp \
    src/gzip/gzip.cpp
./build/out

Or with CMake:

cmake -B build && cmake --build build
./build/compression

src/
  main.cpp                       — demo and round-trip tests
  lz77/lz77.h, lz77.cpp         — standalone LZ77
  huffman/huffman.h, huffman.cpp — canonical Huffman coding
  deflate/deflate.h, deflate.cpp — DEFLATE compress/decompress
  deflate/bitstream.h, .cpp      — bit-level I/O (LSB-first)
  gzip/gzip.h, gzip.cpp         — GZIP format with CRC-32