[Qemu-devel] Re: Another SIGFPE in display code, now in cirrus

[Paolo Bonzini <pbonzini@redhat.com>]

On 05/12/2010 05:57 PM, Stefano Stabellini wrote:
> I guess even a src blt pitch of 0 could be useful there, however in
> practice I think the only rop function that was written with this case in
> mind has:
>
> dstpitch -= bltwidth;
> srcpitch -= bltwidth;
>
> if (dstpitch<  0 || srcpitch<  0) {
>      /* is 0 valid? srcpitch == 0 could be useful */
>      return;
> }

Note that here srcpitch == 0 is actually srcpitch == bltwidth, which 
_is_ obviously useful.

The "real" srcpitch == 0 case would result in srcpitch == -bltwidth, and 
it is actually quite useful if you want to stretch a Nx1 bitmap to NxN.

Paolo