[openbeos] Re: app_server: MMX/SSE help wanted

Adi Oanca <e2joseph@xxxxxxxxxx> wrote:
> > So from the SIMD coders perspective, it would be very good if Haiku 
> > would 
> > offer some control over data alignment for bitmap allocations.
> > This includes not only the base address of the bitmap, but should 
> > ideally 
> > extend to each bitmap row, in cases where each row has to be 
> > processed 
> > separately (e.g. by blur routines:). 
> > 
> > Of course there'd be some 'waste', but I don't think this would 
> > matter too 
> > much on modern systems. Binary compatibility shouldn't be a problem 
> > either, 
> > as the BeBook already says that BytesPerRow() are decisive on 
> > determing a 
> > bitmaps actual size.
> > 
> > This might be implemented by an additional constructor without too 
> > much 
> > fuss, I'd guess. It would be great if you could implement this, as 
> > this 
> > would make SIMD coding much easier and less bug-prone.
>       OK, you'll have that. Now, I have to see how. :-) Axel, can you 
> help?

What he means is: we would need a change of the public API, that is add 
another BBitmap constructor that allows an alignment. What we could 
also do is to add another bitmap flag to force an ideal alignment for 
the current CPU.


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