Lempel-Ziv 78 Compression Algorithm

Short Description

Lempel-Ziv Compression is a core componeent of modern compression algorithms used throughout the internet. Without it, we would struggle to store, send, or share most of the information we do today. This program contains two executables, encode and decode, with can compress and decompress a file, respectively. Only a file encoded by this specific algorithm can be decoded using the executable because of a static magic number written into the file to verify it will use the same algorithm to decode the executable. While this algorithm can be used for all data types, it is best suited for plain text since the encoding algorithm is optimized for repeated symbols.

How to Build

To build, you must have the Makefile. This operates by collecting the C files, generating the object files, and linking them into the binary executable. You must have all of the .c and .h files from this repository to build. Once you have all the appropriate files, you can build each executable independantly or all together at once. To build all the files:

make

or

make all

To make each executable independantly:

make encode
make decode

To see the command line arguments for each executable, run the following commands or see below.

./encode -h
./decode -h 

Encode Command Line Arguments

• -i input_file: Compresses contents from input_file (default: stdin)
• -o output_file: Compressed data is placed into output_file (default: stdout)
• -v: Enables verbose program output
• -h: Prints help usage

Decode Command Line Arguments

• -i input_file: Decompresses contents from compressed file input_file (default: stdin)
• -o output_file: Decompressed data (original message) is placed into output_file (default: stdout)
• -v: Enables verbose program output
• -h: Prints help usage

To Run

The following is an example of how to encode a message in input.txt and output that encoded message to encoded.txt. It will then decode that encoded message into output.txt. Other inputs will be default.

First, encide the message in input.txt:

./encode -i input.txt -o encrypted_message.txt

Now an encoded message is located in encoded.txt.

Finally, decode that encoded message and place the output into output.txt:

./decode -i encode.txt -o output.txt

Now the message in input.txt and output.txt are the same.