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Mail Archives: djgpp/1997/06/01/14:19:31

From: ellman AT xs4all DOT nl ()
Newsgroups: comp.os.msdos.djgpp
Subject: Re: Allegro & sprite stretching optimization
Date: 1 Jun 1997 13:15:41 GMT
Organization: XS4ALL
Message-ID: <5mrslt$a36$1@news0.xs4all.nl>
References: <01bc6d4e$720f1900$ec3e63c3 AT default> <EB25Mr DOT 1HG AT world DOT std DOT com>
NNTP-Posting-Host: xs2.xs4all.nl
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To: djgpp AT delorie DOT com
DJ-Gateway: from newsgroup comp.os.msdos.djgpp

Another problem with Allegro's compiled sprite stretcher is that for sprites
with a large width, you risk overflowing the cache with the compiled line
stretcher, causing it to be re-loaded into the cache for each line.

486s have the aditional problem of a single code and data cache, which means
that when data is written to memory, it sometimes replaces some code that's
in the cache. Pentiums have seperate code and data caches, but you must make
sure the stretcher can fit in the cache.

This routine works best on 386s with no cache, and when the destination
size has a small width. However, as you add extra things to the sprite
stretcher (such as translucency, Z-buffering, etc. (BTW, I've already added
these things to the stretcher compiler myself, and hopefully, Shawn will
include them in the next version of Allegro)), the ammount of code per pixel
gets larger.

AE.

--
Andrei Ellman -- URL: http://www.xs4all.nl/~ellman/ae-a -- ae1 AT york DOT ac DOT uk
"All I wanna do is have some fun     :-)      ||  ae-a AT minster DOT york DOT ac DOT uk
 I've got the feeling I'm not the only one"   ||  mailto:ellman AT xs4all DOT nl
     -- Sheryl Crow      :-)    ||       It's what you make of it. 

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