deep blue InfiniMap

CommonMap revision changed the lookAt/scrollTo interface of background layers to take unsigned positions. After all, it shouldn't be possible to set the center of the screen into negative coordinates when the top-most corner is (0,0).

But I will need to keep internal computation of signed integers anyway. else I get blue meditation screens...

The core of the problem is that processors have two main way to understand numbers: one where the top bit of the number has no special meaning (we call them 'unsigned' numbers and they're all positive), and one where it tells whether the number is positive or negative (with some tweaks, and we call them 'signed' numbers). And among the operations the CPU can perform on number one behaves very differently on signed and unsigned numbers: division. Divide an unsigned number by two, and you'll always have to insert a zero in the top bit. Divide a signed number by two and the top bit remains sticky.

If you mess with the numbers signedness (issue unsigned operations when you should have used signed operations) and you may easily turn a small, negative number into a big, positive number during a division. That's what I did with my update ... this is what I have to fix now... hmm... tomorrow. It's time I give my eyes and brain some rest.