Pixel perfect 2D collision detection with Allegro

Hi all,
I'm struggling with implementing pixel perfect 2D collision detection for my simple 2D game. I'm also using Allegro, if that helps.

I know what the basic algorithm is, but... is there a way for me to use allegro to simplify this?

Notes:
I have sprites loaded from bitmaps, but I rotate them according to the way they're facing (360 degrees are possible) I've also created a parallel list of mask bitmaps with black for where there's background and white for where that pixel is part of my character.

You might want to look at some sample source for collision detection. I don't use Allegro, but I know there are several SDL libraries that do this.

[edit] You might try google, if you haven't already: http://www.google.ca/search?hl=en&q=...etection&meta= [/edit]

[edit=2] This should probably be in the Game Programming Forum. Nothing you can do about it now, though. [/edit]