Cirrus: BLT with coordinate overflow does not update screen, may crash

[finnbrudal]

BLT operations that occur across screen edges fail to update the screen. For example, this may occur with decrementing BLTs along the left or top sides of the screen, or an unaligned color expansion BLT to the left side of the screen. An overflowing destination address, such as with an unaligned color expansion BLT to the top left corner, makes Bochs crash.

[vruppert]

I have now fixed the redraw values for backward BitBlt. According to the specs color expansion cannot be used with decreasing addresses. Please let me know if there are still issues.

[finnbrudal]

This sets w and h to 0 as well and makes Bochs freeze for several seconds. For the backwards case, incrementing both redraw.x and redraw.y by 1 fixed the original problem. The other problem is with (forwards) unaligned BLTs on the left side, that start before the beginning of the scanline. By adjusting the destination address according to the left side clipping settings before it is used in any calculations, this problem should be taken care of as well.

[vruppert]

Oops...
I'm sorry for that mistake. I have now applied a better version. Do you have a test case for the other part of the issue? I also need one for your pull request.

[vruppert]

Are all of the Cirrus issues you reported fixed now?

[finnbrudal]

Yes, everything seems to work now.