On Tue, Aug 11, 2009 at 06:52:35AM +0000, Chris Miller wrote:
private int roundDown(int val) { return val >> SHIFT << SHIFT; } I would write this as
return val & ~(1 << SHIFT);
That's not the same thing though. I assume you really mean:
return val & ~((1 << SHIFT) - 1);
And in fact that's what was there originally for positive numbers. Negative numbers were handled differently, for reasons I don't understand (hence why I'm asking on here).
Oh, sorry, you are right, I forgot the -1.
I think I still prefer val >> SHIFT << SHIFT, it's clearer what's happening (to me at least, I appreciate everything thinks about these things differently). It's also fewer clock cycles unless you're on a 286 or lower ;) Though the clock cycle argument isn't relevant here, the code is only called twice during the entire split!
If that is the case, then it is better to aim for readability and maintainability. The bit-shifting expression should be easier to read than the monster bit-masking expression. And because you are shifting the same amount right and left, it won't matter whether you are using arithmetic or logical right shift (>>> or >> in Java). Sorry for the noise. Marko