From: "Graham Reeds" <grahamr AT dtn DOT ntl DOT com>
Newsgroups: comp.os.msdos.djgpp
References: <6v%E5.29784$L12 DOT 598411 AT news2-win DOT server DOT ntlworld DOT com> <8s49vu$k4l$1 AT slb6 DOT atl DOT mindspring DOT net> <JAlF5.31810$uq5 DOT 615829 AT news6-win DOT server DOT ntlworld DOT com> <8s4uou$381$1 AT slb7 DOT atl DOT mindspring DOT net> <AIsF5.46659$L12 DOT 677834 AT news2-win DOT server DOT ntlworld DOT com> <8s73ft$fvg$04$1 AT news DOT t-online DOT com> <j1IF5.1086$NQ4 DOT 21429 AT news2-win DOT server DOT ntlworld DOT com> <8s9ka0$pgg$04$1 AT news DOT t-online DOT com>
Subject: Re: VBE2.0 w/LFB + GCC
Lines: 58
X-Priority: 3
X-MSMail-Priority: Normal
X-Newsreader: Microsoft Outlook Express 5.50.4133.2400
X-MimeOLE: Produced By Microsoft MimeOLE V5.50.4133.2400
Message-ID: <%S1G5.3521$NQ4.79911@news2-win.server.ntlworld.com>
Date: Sat, 14 Oct 2000 19:46:13 +0100
NNTP-Posting-Host: 62.254.81.161
X-Complaints-To: abuse AT ntlworld DOT com
X-Trace: news2-win.server.ntlworld.com 971549243 62.254.81.161 (Sat, 14 Oct 2000 19:47:23 BST)
NNTP-Posting-Date: Sat, 14 Oct 2000 19:47:23 BST
Organization: ntlworld News Service
To: djgpp AT delorie DOT com
DJ-Gateway: from newsgroup comp.os.msdos.djgpp
Reply-To: djgpp AT delorie DOT com

> - After you decide about LFB or bankswitching, you calculate the remainder
>   and videomemory pointer again with the bankswitching formula.
>   So you destroy them both in the case of LFB.
>   That's why you had only a fraction of your image on the screen

Oops.  My mistake - I was so concerned that the problem was higher in the
code than that I never noticed it.  Thanks it now works fine.

> - You allocate your "primarysurface" AFTER you calculate the remainder
> stuff.
>   This works for LFB, because you don't use it with the LDT descriptor
>   allocating part.
>   But as soon as bank switching is used, you will get a crash.
>  Put it before
>
>     if (vbeinfoblock.vbeversion >= 0x0200)
>

It never seemed to bother my original version of my code, or the rewrote
vbe1.2.  This code is just an extension of that with some new bits stuck in
, and one that compiled correctly about 2 years ago when I used to program
in gcc 100%.  Now I program 60/40 MSVC / GCC (though it seems to be back to
100%).  I decided to go through all my old code and get everything look nice
and orderly, with proper variable names (int thack1, thack2; anyone?).
Seems with time, applications just fall apart...

> - You calculate the remainder to be xres*yres. This is OK, because with
LFB
>   you can copy the full screen at once. But you use _movedatal() for this,
>   which gets the number of DWORDS to copy, but you give it the number of
> BYTES.
>   Either calculate remainder to be xres*yres/4 or divide it at the
> _movedatal()
>   call.

Sorry, another one of those grasping at straws moments... I've put it back
in.

> - Your calculation of the bankswitch-remainder works, but the modulo
> operator
>   is predestinated to calculate remainders :-) Why don't you use it?

I thought that the modulo calculates the number of x in y - ie: 145%12 = 12.
Oh well, you live and learn!-)
Seriously though.  I always use rand()%100, to return a number between 0-99,
so that's how I thought of modulus operating.

Thanks for all your help, any other suggestions would be welcome.

--

Stay Lucky, Graham "Mournblade" Reeds.
ICQ No.:  30514803
http://homepage.dtn.ntl.com/grahamr