[Vm-dev] Integer overflow with BitBlt rule 20 and depth 32

Henrik Johansen henrik.s.johansen at veloxit.no
Fri Oct 30 09:09:36 UTC 2009

Not that it matters on 32bit architecture, but don't you in theory  
have to use unsigned long to ensure an integer of at least 32 bits is  

Other than that I see no problems, until someone decides to add depths  
 > 32. (And then you'd have to modify the methods anyways).


On Oct 30, 2009, at 3:10 42AM, David T. Lewis wrote:

> On Mon, Oct 26, 2009 at 11:57:16AM -0700, Eliot Miranda wrote:
>> On Mon, Oct 26, 2009 at 11:07 AM, Juan Vuletich  
>> <juan at jvuletich.org> wrote:
>>> Anyway, I'm asking for help on making #copyBitsSimulated work  
>>> again, like
>>> it should do when called from BitBltTest. If nobody can help with  
>>> that, I
>>> guess I'll open a Mantis issue for this problem, in the hope that  
>>> some day
>>> it gets fixed.
>> Well with my current VM I see no problems; all 10 tests are green.   
>> What is
>> the bug that you see?  How can I reproduce it?
> Juan provided six new tests (see Mantis 7047) that document the  
> problems.
> I added these six tests to the trunk today, and also updated VMMaker  
> on
> SqueakSource with Juan's fixes for bitblt simulation (mainly some  
> memory
> access methods that had apparently been overlooked during the original
> Squeak 64 bit work).
> Juan's patches (VMMaker-BitBlt-AlphaFixes-jmv-M7407.cs on Mantis 7047)
> do resolve the problems in the VM, and the changes all look correct  
> to me
> (but I have no experience with bitblt, so I'm just commenting on the  
> fixes
> for type declarations and arithmetic overflow).
> Has anyone else had a chance to review this? If there are no issues or
> concerns, I will add Juan's alpha fixes to VMMaker.
> Dave

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