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Mail Archives: djgpp/1996/10/28/16:28:59

From: Brad Spencer <stud73 AT bnr DOT ca>
Newsgroups: comp.os.msdos.djgpp
Subject: Re: Graphics slow?
Date: Mon, 28 Oct 1996 14:39:46 -0500
Organization: Nortel
Lines: 27
Message-ID: <32750C02.6BC0@bnr.ca>
References: <Pine DOT GSO DOT 3 DOT 94 DOT 961027145010 DOT 27194A-100000 AT zippy>
NNTP-Posting-Host: bcarhd6d.bnr.ca
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To: djgpp AT delorie DOT com
DJ-Gateway: from newsgroup comp.os.msdos.djgpp

I don';t have the original poster's address, so I'll reply here..

> On Sat, 26 Oct 1996, Indrek Mandre wrote:
> 
> >    First I must say that I am a beginner in programming djgpp.
> > This far I have only programmed on Linux. Some weeks ago I got
> > djgpp 2 and I began to like it. But now I have some problems.
> > On Linux I programmed graphics and used svgalib. There I mostly
> > wrote my own fast asm code and used only some svgalib parts for
> > graphics modes seting, bank/page switching/seting, scrolling.
> > I ported one of my programs to djgpp and used Allegro (bliting and
> > double buffering, virtual bitmaps and so on). I tested it and
> > it was precisely 2 times slower than on a Linux. Is this normal?

"Precisely 2 times slower" sounds suspiciously like you might be waiting
for retrace twice.  If svgalib's page-flip routine doesn't wait for
vertical retrace and Allegro's does (I don't know if this is the case),
then you probably have separate waits in your own code.  This would
make your program wait an extra frame every time (twice the delay)
with the new library.  Of course, it could be something more evil :)

-- 
------------------------------------------------------------------
Brad Spencer - spencer AT ug DOT cs DOT dal DOT ca - in CS @ Dalhousie University
    Currently working in a co-op position at Nortel Technology
[Surprisingly enough, my views are not always those of my company]
"S.M.A.K.I.B.B.F.B." - A.J. Rimmer | http://ug.cs.dal.ca/~spencer/

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