That's a pretty standard way to comment out a huge chunk of code, because /* */ will get screwed up if there's another comment using the same convention ins

That's a pretty standard way to comment out a huge chunk of code, because /* */ will get screwed up if there's another comment using the same convention inside, and putting // in front of every single line looks bad/makes copying code around painful. #if 0 is also a convenient way to flip bits of test/debug code on and off.