Re: [AD] Optimized blitting between color depths

[Sven Sandberg <svens@xxxxxxxxxx>]

Elias Pschernig wrote:
> I get this results (running your test program 3 times), Intel P4:
>
> 54,54,54 dithered, keep trans  
> 63,62,63 dithered, no keep trans
> 55,55,55 non-dithered, keep trans
> 107,107,107 non-dithered, no keep trans
>
> The first 3 lines look good - but what does the last line mean?

Just to be sure: did you did you link my program twice, against 
different versions of Allegro? The numbers that my program prints are 
not percents, but milliseconds, so you have to compute percents 
manually. If you did that right, it's a bit strange. I should admit I 
also got 1% slowdown for non-dithered, no keep trans -- I thought it was 
within the error margin, but 7% sounds worse. The actual code for this 
case is unchanged, except there is one `if' less in the new version 
(compare the CONVERT_BLIT macro in the old version with the 'else' 
branch of CONVERT_BLIT_EX in the new version). The only explanation I 
can think of is bad luck with code alignment or something like that. 
It's bad, because it's probably the most common case. I guess it would 
be interesting to see what happens on other architectures too...

/Sven