From:	"Randy Sorensen" <randy AT NOSPAM DOT idcomm DOT com>
Newsgroups:	comp.os.msdos.djgpp
Subject:	Optimized code, comparing with Borland C++ 4.5 w/ Power Pack
Date:	Sun, 8 Mar 1998 17:01:04 -0700
Lines:	45
NNTP-Posting-Host:	208.13.36.190
Message-ID:	<350334da.0@superego.idcomm.com>
To:	djgpp AT delorie DOT com
DJ-Gateway:	from newsgroup comp.os.msdos.djgpp

It probably goes without saying, but I'm somewhat of a newbie to gcc in
general, and especially DJGPP (used gcc on Linux a bit).  So if this is a
dumb question, you'll just have to shoot me.

I bought a book a few weeks ago called _Cutting Edge 3D Game Programming
with C++_ by John De Goes.  The book has some nice texts on 3D coding, but
the way they did the sample code just plain sucks.  The author used Borland
C++ 4.5, and also used Borland's PowerPack, two things that I don't own.
I'm not sure what the PowerPack does, but the code doesen't work with BC++
4.0 without it, and the folks on IRC say it doesen't work on 4.5 without the
PP either.  It's DPMI code, and so I figured it would be pretty easy to port
it to DJGPP.  As it turned out, it was.  Which was nice, since code that
uses Borland's DPMI manager can only run on DOS (you have to shut down out
of Windows).

Here's my problem.  When I do shut down out of DOS and run the exec's
included on the CD, they run up to 60 fps, where as the code that I ported
to DJGPP runs at 40 fps with the following optimizations:
"-O6 -ffast-math -funroll-loops -finline -m486".  Is there any other
optimizations that will speed it up?  Also, I've heard that using high
"-O"'s will cause problems.. should I bring it down to 4 or 3?

I should note that when I ported the code, the original author didn't do a
very "standard" job with it.  Some of the matrix vector and point
transformation code was inlined (they were C++ methods) and I couldn't
figure out how to make DJGPP inline them.  Also, since you can't write to
video memory in DJGPP by default, I went about doing so using
__djgpp_nearptr_enable() and adding __djgpp_conventional_base to the video
memory address.  Is there a faster way of going about video memory writing?
And lastly, I had to put some extra type-casts in there, since gcc.exe kept
giving me warnings about assigning doubles to unsigned char's and stuff.

Thanks for all your help :) I'd appreciate it if you emailed me rather than
posted a response, since I don't check the groups or the listserv very
often.

--
-Randy Sorensen
randy AT REMOVE_THIS_TO_EMAIL_ME DOT idcomm DOT com
You must remove the first part of the domain on my e-mail address to send me
mail, or else it will not go through.  I'm very sorry for this, but it's the
only way I can keep the "Free Live Hot Sex" headers out of my inbox every
day.  Thanks!

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