On Mon, 15 Jun 2020, Peter Maydell wrote:
On Mon, 15 Jun 2020 at 17:40, BALATON Zoltan <bala...@eik.bme.hu> wrote:
On Mon, 15 Jun 2020, Peter Maydell wrote:
The calculations for sb/se/db/de all have a term which
multiplies by (width + pitch), which makes me suspect
they also need a similar fix ?
Maybe. I'll have to check again. Actually is there a simpler way to check
if two rectangles overlap when they are given with base, x, y, w, h, pitch
where base is the first byte of the screen, pitch is length of one line
and x,y is coordinates of top left corner and w,h is dimensions of the
rect. Now that I think about it we also need to take into accounf the
bytes per pixel value (1 << format) because base is given in bytes while
others are in pixels so these formulae likely need some fixes. Pixman has
some functions for these but those assume common base so to use those we
would need to bring the two rectangles to common base which I could not
find out how to do. Probably this is really simple for someone who already
did a lot of these before.
I think the thing that makes it particularly awkward is that
the source and dest can have different pitches. That means it's
Yes, different bases and different pitches make it difficult to compare
and also to transform them to a common base to be able to do rectangle
overlap test (I haven't checked but maybe the pitches could be relative
prime so it's possible there's no common pitch to transform them to a
single view).
not a simple "do two rectangles overlap" test because the dest
area might not be a rectangle at all when looked at from the
POV of the source.
Do guests usually set src and dst pitch identical? If so it
might be worth having a more accurate rectangle-overlap test
for the common case and a looser check for the hard-to-handle
case.
Quick test (just booted AmigaOS, opened some windows and moved them around
a bit) shows same pitch is common but not always:
7610 sm501 2d engine regs : write addr=10, val=200020
4249 sm501 2d engine regs : write addr=10, val=4000400
2340 sm501 2d engine regs : write addr=10, val=4000080
462 sm501 2d engine regs : write addr=10, val=40000a0
453 sm501 2d engine regs : write addr=10, val=800080
434 sm501 2d engine regs : write addr=10, val=1200120
233 sm501 2d engine regs : write addr=10, val=4000020
162 sm501 2d engine regs : write addr=10, val=400040
144 sm501 2d engine regs : write addr=10, val=200080
141 sm501 2d engine regs : write addr=10, val=2000a0
75 sm501 2d engine regs : write addr=10, val=600060
62 sm501 2d engine regs : write addr=10, val=a000a0
62 sm501 2d engine regs : write addr=10, val=200400
38 sm501 2d engine regs : write addr=10, val=e000e0
38 sm501 2d engine regs : write addr=10, val=1000100
38 sm501 2d engine regs : write addr=10, val=10000a0
37 sm501 2d engine regs : write addr=10, val=4000040
36 sm501 2d engine regs : write addr=10, val=40000e0
34 sm501 2d engine regs : write addr=10, val=a00080
34 sm501 2d engine regs : write addr=10, val=4000120
33 sm501 2d engine regs : write addr=10, val=400080
25 sm501 2d engine regs : write addr=10, val=600080
23 sm501 2d engine regs : write addr=10, val=4000060
22 sm501 2d engine regs : write addr=10, val=1a001a0
and may depend on what the guest is doing so not sure it's worth the
effort. (Probably same pitch is used when moving window and different when
drawing something like text or icons but different pitch likely uses
off-screen bitmap as source so overlap is not likely for those.)
I might have a think about this and draw some diagrams tomorrow :-)
I'll wait for that to see if you can come up with something clever. I've
tried to find a solution but could not come up with anything simpler than
a loop checking lines which is probably as much effort as doing the blit
itself and then doing blit with a temporary is probably the same so I went
for just checking the obviously far apart blits (and even that seems to be
easy to miss). So I'm happy if we can just fix the checks we have but if
there are better suggestions please tell me.
Regards,
BALATON Zoltan
