From:	George Foot <mert0407 AT sable DOT ox DOT ac DOT uk>
Newsgroups:	comp.os.msdos.djgpp
Subject:	Re: DJGPP too slow!
Date:	22 Nov 1997 00:20:39 GMT
Organization:	Oxford University, England
Lines:	28
Message-ID:	<6558gn$ilq$3@news.ox.ac.uk>
References:	<34755A66 DOT 1845 AT trash DOT lip6 DOT fr>
NNTP-Posting-Host:	sable.ox.ac.uk
Mime-Version:	1.0
To:	djgpp AT delorie DOT com
DJ-Gateway:	from newsgroup comp.os.msdos.djgpp

On Fri, 21 Nov 1997 09:54:46 GMT in comp.os.msdos.djgpp Fabrice ILPONSE <fabrice AT asim DOT lip6 DOT fr> wrote:

: Here's the topic back.

: 	That time have made a new test concerning video memory access.

: 	Results:
: 		- BC 16 bits red takes  40% of screen height
: 		- BC 32 bits 45 - 50%
: 		- DJGPP      90 - 95%

You didn't post or offer to supply the code you used to do this...

: 	Protected mode perhaps!

Yes indeed; if the blitting technique you used involves a lot of
selector juggling and so on this will slow things down, especially if
you do the selector selection inside your blitting loop.  Using
nearptrs should be fast, especially using a 32-bit memory copy.  Using
farptrs should be nearly as fast, if you do the _farsetsel outside
your loop, and use the 32-bit copying function.  Since this is only a
verbatim blit, you could use generic memory movement functions too --
dosmemput, for instance.  What did you do?

-- 
Regards,

george DOT foot AT merton DOT oxford DOT ac DOT uk

- Raw text -