Re: [r200] 'readpix' sigfault back trace SSE/MMX is culprit

[Roland S. <rsc...@hi...>]

Dieter N=C3=BCtzel wrote:
>>Looking a bit at this, this seems to be caused because the number of
>>pixels to read can be less than zero after CLIPSPAN (don't know if
>>that's a bug in itself or not).
>=20
>=20
> That was my first thought, too (moving the window out to the left...) ;=
-)
>=20
>=20
>>This is no problem for the generic read (since the for loop will just
>>terminate instantly), but the mmx/sse/sse2 optimized routines only test
>>if it's 0 pixels to read, and don't bail out if it's less than zero. I
>>haven't looked closely what exactly will happen (i.e. the loops may
>>never terminate at all), but this certainly seems like a bad thing...

Here's a one-liner fix, which will cause CLIPSPAN hopefully never return=20
a negative n1. Seems to work here.
Ian, what do you think? Would it be better to have the optimized=20
read/write functions deal with negative values instead?

Roland