arithmetic-coding-go

README

Adaptive Arithmetic Coding in Go

This repository contains a Go implementation of adaptive arithmetic coding, specifically utilizing a variant of the method described by Tjalling J. Willems.

Features

• Adaptive Model: Frequencies are updated on-the-fly, allowing the model to adapt to the data being processed.
• Binary Arithmetic Coding: Operates at the bit level, providing high compression efficiency.
• Willems' Variant: Uses a frozen state to prevent frequency overflow, ensuring stable and accurate compression over long data streams.

Installation

To install this package, you can simply clone the repository:

git clone https://github.com/lazarus/arithmetic-coding-go.git

Or use Go modules to include it in your project:

go get github.com/lazarus/arithmetic-coding-go

Usage

Basic Example

Here’s a simple example of how to use the library to encode and decode a file:

package main

import (
	"fmt"
	"github.com/lazarus/arithmetic-coding-go/ac"
	"log"
	"os"
)

func main() {
	fileName := "ex.txt"
	data, err := os.ReadFile(fileName)
	if err != nil {
		log.Fatalf("Failed to read file: %v", err)
	}

	context := ac.NewContext()
	encoded := context.Encode(data)

	fmt.Printf("Original size: %d bytes, encoded size: %d bytes\n", len(data), len(encoded))

	context = ac.NewContext()
	decoded := context.Decode(encoded)

	fmt.Printf("Encoded size: %d bytes, decoded size: %d bytes\n", len(encoded), len(decoded))

	if string(data) == string(decoded) {
		fmt.Println("Success: The original and decoded data match!")
	} else {
		fmt.Println("Error: The original and decoded data do not match.")
	}
}

API Overview

• NewContext: Initializes a new encoding/decoding context.
• Encode: Encodes a slice of bytes into a compressed format.
• Decode: Decodes a previously encoded slice of bytes back into the original data.

Example File

Place your input file (ex.txt) in the same directory as your Go program, and run the above example to see the encoding and decoding process in action.

License

This project is licensed under the MIT License. See the LICENSE file for details.

Contributions

Contributions are welcome! Feel free to open an issue or submit a pull request.

Acknowledgments

This implementation is based on the adaptive arithmetic coding method described by Tjalling J. Willems.