[PATCH v2] Try and get overlapping cases fixed.

[Stefan Ring]

> I'm assuming this patch is still useful? Bug 36165 is on the 1.11
> tracker.
>
> If it's useful, I'll merge it in (with the divide operations replaced
> with bit operations; yes, I looked at the assembly output; bpp is
> signed, making the operations longer).

It is very useful. This problem is the cause of two image corruption
bugs in the RedHat Bugzilla -- once for tigervnc [1], once for
xorg-xserver [2]. Both carry around varying versions of the patch in
question [3, 4]. Please also have a look at my responses to this
thread [5, 6].

[1] https://bugzilla.redhat.com/show_bug.cgi?id=652590
[2] https://bugzilla.redhat.com/show_bug.cgi?id=665320
[3] http://pkgs.fedoraproject.org/gitweb/?p=tigervnc.git;a=blob;f=0001-Use-memmove-instead-of-memcpy-in-fbblt.c-when-memory.patch;h=50d6c53437d6c9db6e1f50d5495f31728e78f06f;hb=9956c17c57d2ce920b8f8f9985c05a0ceebde20a
[4] http://pkgs.fedoraproject.org/gitweb/?p=xorg-x11-server.git;a=blob;f=xserver-1.10.1-memcpy-abuse.patch;h=e3b1b9772d82680827c236571239d9103a6f10a3;hb=f15
[5] http://lists.x.org/archives/xorg-devel/2011-July/023815.html
[6] http://lists.x.org/archives/xorg-devel/2011-August/024266.html