This implementaion of file system is developed by ELM Chan
http://elm-chan.org/fsw/ff/00index_e.html.  

This is based on FAT file system specification.  It provides
an interface to physical storage management through its disk io
API in diskio.c. The disk io interfaces are updated to interface
with Zephyr flash memory management.

Current revision in the tree is 0.15

URL to current version: http://elm-chan.org/fsw/ff/arc/ff15.zip