Entropy Adaptive Coding

Overview

This is an experimental implementation of Entropy Adaptive Coding algrorithm on top of simplest Lempel Ziv 77 algorithm. This project is intended for testing EAC and comparing it against simple Lempel Ziv 77 compression.

Requirements

To compile and run this project following are required:

1. gcc version >= 4.8
2. Embedded GNU C Library >= 2.17
3. phtread support
4. doxygen >= 1.8.5 (for documentation generation only)

Compilation

To compile this project first clone it using git. After that enter into directory tests and run there ./update_tests.sh to download latest test files from S3. After that run make in project directory to compile all binaries.

Usage

There are 2 binaries that are provided are compiled:

1. eac_encode - this is encoder that can compress files using both LZ77 and EAC algorithms.
2. eac_decode - this is decoder that can decode files encoded with eac_encode.
3. entropy_calc - a small program that calculates binary entropy of a file.
4. generator - generates file of given size with given entropy (approximately). Additionally there are a few scripts in tests directory:
5. sanity.sh - sanity tests for both LZ77 and EAC encoding and decoding. Validates that files are properly encoded and decoded.
6. perf_single.sh - this script runs test on single file by running eac_encode and eac_decode cycle on it with specified parameters. Output is written into file named after parameters in results/ directory.
7. performance.sh - script that runs perf_single.sh on all test files with all possible configuration parameters. After running all CSV report is generated.
8. jsonReport.php - PHP script that converts result.csv file into result.json. Stores result in viewer/result.json

Documentation

Internal documentation can be compiled using command make doc. For generating documentation doxygen version 1.8.5 or later is needed. After running make doc documentation will be accessible in

• doc/html - in HTML format
• doc/latex - in Latex format (can be compiled into PDF by running make pdf in that directory)

Graphical result viewer

Simple graphical result viewer is written using HTML/CSS/JS. It uses jqPlot to show data as graph. To use graphical viewer result.csv must be first converted into result.json. For this there is a script called jsonReport.php in tests/ directory. After running it using graphical viewer is as simple as opening viewer/index.html in browser.

Graph images generator

All graphs that can be viewed using Simple graphical result viewer, can be generated into image files (PNG) using PHP script graphgen.php. This script accepts results.csv file as parameter and generates images into tests/images directory. To work correctly this script requires PHP version 5.4 or later.