Date: Mon, 6 Jan 1997 11:11:41 +0100 (MET)
From: Robert Hoehne <robert DOT hoehne AT mathematik DOT tu-chemnitz DOT de>
To: Bill Currie <billc AT blackmagic DOT tait DOT co DOT nz>
Cc: "Salvador Eduardo Tropea (SET)" <salvador AT natacha DOT inti DOT edu DOT ar>,
        Robert Hoehne <robert DOT hoehne AT mathematik DOT tu-chemnitz DOT de>,
        DJGPP workers <djgpp-workers AT delorie DOT com>
Subject: Re: Question about exceptions
In-Reply-To: <32C4FACF.176A@blackmagic.tait.co.nz>
Message-Id: <Pine.HPP.3.95.970106110410.16780E-100000@newton.mathematik.tu-chemnitz.de>
Mime-Version: 1.0
Content-Type: TEXT/PLAIN; charset=US-ASCII

On Sat, 28 Dec 1996, Bill Currie wrote:

> > without an smart swap but ... swapping 256Kb of video memory isn't
> > very fast.
> 
> Why swap all 256k, just the few k needed for the text page (and font
> info) is all you need to swap (about 18 k, 8k for the font and 10800
> (90x60) for the text).
That's not correct. Over the holyday I had the time to test and make
the code for graphic display swapping. After many many tries, because
I found nowhere a good documentation about VGA register programming,
I got it now to work.

But I found, that you have to save/restore 32K of memory, because
all the text video memory is touched when you switch to any text
mode (even when the 'no clear screen' flag is set when switching
the video mode).

> Will your code be available for the full screen debugger as well?

I have the code for saving/restoring the screen contents in two
files (one for the vesa modes and one for the VGA modes 0x12 and
0x13). These files can be used also in any other program so if
you want, you can get them and integrate the code in FSDB.

(I wrote the files as C++ files, but only because there is a betther
warning checking of gcc).

Robert
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* Robert Hoehne, Fakultaet fuer Mathematik, TU-Chemnitz-Zwickau *
* Post:    Am Berg 3, D-09573 Dittmannsdorf                     *
* e-Mail:  Robert DOT Hoehne AT Mathematik DOT TU-Chemnitz DOT DE              *
* WWW:     http://www.tu-chemnitz.de/~rho                       *
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