RE: [AD] minor issues

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MMX clear was an improvement only on the Pentium MMX line of chips.

-----Original Message-----
From: alleg-developers-admin@xxxxxxxxxx [mailto:alleg-developers-admin@xxxxxxxxxx] On Behalf Of Elias Pschernig
Sent: Thursday, January 27, 2005 2:05 PM
To: alleg-developers
Subject: Re: [AD] minor issues

On Thu, 2005-01-27 at 21:52 +0100, Julien Cugnière wrote:
> Elias Pschernig a écrit :
> 
> > Then, as Peter said, there's the problem if we can assume that lines are
> > continuous. If we make this change, then we should specify that
> > is_memory_bitmap(bmp) means that there can be no line gaps (and also
> > check that no other memory bitmaps are currently created by Allegro).
> 
> Make that rather "is_memory_bitmap(bmp) && !is_sub_bitmap(bmp)". Sub-bitmaps 
> will have gaps, so the trick unfortunately won't work with them.

Ah, true, of course. Probably best to provide an is_linear_bmp.. wait -
that function already exists. I wonder if it could just be used (and its
meaning extended to mean: linear bitmaps can have no line gaps).

> > Oh, and do you think something similiar can be done for clear_to_color?
> > That's what really would bring an improvement to actual programs, since
> > normally you need to clear to some color, not just 0.
> 
> What would really be an improvement is if memcpy was faster than blit... who 
> knows :-)
> 

Heh. This actually makes me wonder. Maybe just looping over the line
pointers and doing a memcpy for every line really is faster.. MMX
doesn't seem to be an improvement for clearing to 0 in any case. Hm, I
will test clear_bitmap with MMX disabled, and with the C only version -
maybe then it is as fast as memset again, and we don't need to modify
anything - just start wondering a lot why it is so..

-- 
Elias Pschernig



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