Simple 2D game... Simple collision? Probably not? =-=

Thinking on my next step on my game that's start coding the whole stuff, [s]so I can realize I'm not gonna make it and give up already[/s], and I have to choose an engine...
HGE's great for it's simplicity, how they say, make games, not engines! But Allegro seems more powerful and is a lot more realiable, not to mention it's cross-platform, [s]as if anyone cares for cross-platforming[/s]. But yesterday I discovered pmask, a really good collision utility for allegro and SDL! It's detection is perfect and it's unbelievably fast for that kind of precision...

For those interested: PMASK
There're two exe demo showing it's incredibly good performance and detection precision! Give them a try!
Did I say it is "pixel perfect"? D:

@Edit: It turns out that PMASK is only Allegro4... what a disappointment! Anyway, the author's released his work (thanks for it if you're reading this haha) on public domain, anyone can port it!
I guess I'll have to read his code and see how he's done the computing. Maybe I can make a ported version for allegro 5 or maybe I'm laughably wrong thinking it's incompatible...

@Edit2: nightcracker has posted the following files on the comments:
https://raw.github.com/gist/1460947/e94f96497ee759e64828a3e0b3ea7defb170a7b8/bitmask.c
https://raw.github.com/gist/1460953/199aed3e3d6acf9353e25c1eb582c53eaa8777ea/bitmask.h
Thanks again!