I prefer RIES [1], that does pretty much the same thing. You can download its source code (C, GPL licensed) [2] or try it on the webpage. Oblig. (relevant) xkcd [3].

[1] http://mrob.com/pub/ries/index.html

[2] http://mrob.com/pub/ries/src/ries.c.txt

[3] http://xkcd.com/1047/