The software in this package is a Python module for generating objects that compute the Cyclic Redundancy Check (CRC).
It includes a (optional) C extension for fast calculation, as well as a pure Python implementation.
There is no attempt in this package to explain how the CRC works.
There are a number of resources on the web that give a good explanation of the algorithms.
Just do a Google search for “crc calculation” and browse till you find what you need. Another resource can be found in chapter 20 of the book “Numerical Recipes in C” by Press et. al.