This project is a command-line tool for compressing and decompressing files using the Huffman coding algorithm. It is designed for educational purposes (e.g., the Introduction to C module at HSLU) and demonstrates key concepts such as file handling, frequency analysis, tree structures, and bit manipulation in C.

• Binary File Support: Handles any file type, not just text files
• Progress Visualization: Real-time progress bar during compression/decompression
• File Extension Management: Automatic .pda extension handling
• Smart Warnings: Detects and warns about inefficient compression scenarios
• File Handling: Reads input files and generates compressed output files
• Frequency Analysis: Analyzes character frequencies to build optimal Huffman codes
• Huffman Tree Construction: Uses a priority queue to assign shorter codes to frequent characters
• Encoding & Decoding: Compresses and decompresses files using the Huffman algorithm
• Error Handling: Detects and reports invalid input, file errors, and inefficiencies for small files
• Command Line Interface: Simple CLI for compression and decompression

The tool now provides visual feedback during operation:

• Progress bar showing compression/decompression status
• Updates every 16KB of processed data
• Compression ratio reporting after completion
• Warning messages for inefficient compression scenarios

The effectiveness of compression varies significantly depending on the file type:

• Text files (.txt)
• CSV files (.csv)
• Log files (.log)
• Source code files (.c, .h, etc.)
• Raw/uncompressed image files (.bmp)
• Raw data files

• Word documents (.docx, .doc)
• PDF files (.pdf)
• Compressed images (.jpg, .png, .gif)
• Audio/video files (.mp3, .mp4, .avi)
• Archive files (.zip, .rar, .7z)
• Executables (.exe, .dll)

The tool will now warn you when attempting to compress already-compressed file types, as these typically won't benefit from additional Huffman compression.

1. Make sure gcc is installed.
2. Build with the Makefile:

   make

3. The program will be built as huffman.

1. Install MinGW or TDM-GCC and ensure gcc is in your PATH.
2. Open a Bash shell (e.g., Git Bash, MSYS2).
3. Run the build script:

   ./build_windows.sh

4. The program will be built as huffman.exe.

Compress:

./huffman -c <input_file> <output_file>

The compressed file will automatically get the .pda extension.

Decompress:

./huffman -d <input_file> <output_file>

The input file must have .pda extension for decompression.

Example:

# Compress (will create example.pda) ./huffman -c example.txt example # Decompress (will restore original file) ./huffman -d example.pda example.txt

• For very small files (<100 bytes), the compressed file may be larger than the original due to Huffman tree overhead
• The maximum supported file size is 1GB
• The tool is cross-platform and works on Linux, macOS, and Windows (32/64 bit)
• Compression ratio depends heavily on file content and type
• Progress bar provides real-time feedback during operation
• Automatic warnings for inefficient compression scenarios

1. Binary Support: Handle any file type
2. Visual Feedback: Show progress during operation
3. File Handling: Read and write files
4. Frequency Analysis: Analyze byte frequencies
5. Huffman Tree Construction: Build the Huffman tree
6. Encoding Process: Encode and decode files
7. Error Handling: Robust error handling
8. CLI: Command-line interface only

src/ ├── core/ # Core Huffman algorithm │ ├── huffman.c │ └── huffman.h ├── io/ # Input/Output │ ├── bit_io.c │ ├── bit_io.h │ ├── file_io.c │ └── file_io.h ├── compression/ # Compression specific │ ├── encode.c │ ├── encode.h │ ├── decode.c │ └── decode.h ├── utils/ # Utility functions │ ├── frequency.c │ ├── frequency.h │ ├── file_extension.c # Extension handling │ ├── file_extension.h │ ├── progress_bar.c # Progress visualization │ └── progress_bar.h └── main.c # Entry point