I don't know dude because it's included in this package:
http://www.vision.ee.ethz.ch/~surf/S...nDLLVC8.tar.gz

and ****... the source isn't included.

Searching for another opensource implementation of the same algorithm would be a solution but the thought I have to discard a project created with Visual Studio which gives no errors in the compilation process (and that's not a thing every opensource project gives under VS environment), make me want to cry.