From:	Glen Miner <gminer AT ca DOT newbridge DOT com>
Newsgroups:	comp.os.msdos.djgpp
Subject:	Re: Memory Protection
Date:	Sat, 16 Nov 1996 09:31:24 -0500 (EST)
Organization:	Newbridge Networks Corporation
Lines:	40
Message-ID:	<Pine.SUN.3.90.961116092939.24811A-100000@coop10>
NNTP-Posting-Host:	138.120.136.238
Mime-Version:	1.0
To:	Bill Currie <billc AT blackmagic DOT tait DOT co DOT nz>
In-Reply-To:	<328DC8F4.3C96@blackmagic.tait.co.nz>
To:	djgpp AT delorie DOT com
DJ-Gateway:	from newsgroup comp.os.msdos.djgpp

> > > For further protection, you can create a segment that covers only the
> > > video memory and use that instead.
> > 
> > How would this be done? This would be ideal; if you could setup another
> > segment (a 64k window to vidoe memory), and it would be "unprotected",
> > then you could just use the movedata function with that segment's
> > selector, right?
> 
> Here is a code snipet to set up the video selector (it's part of my text
> lib which I'm thinking of releasing soon as it seems to be pretty stable).
> 
> -----------------------
> 
> unsigned short screenSelector; /* selector to use with the various _far*
> and movedata functions*/
> 
> void TxSetupSelector()
> {
>     static char selectorData[8]={
>         0xff,0xff,0x00,0x80,
>         0x0b,0xf3,0x40,0x00
>     };
>     if (screenSelector) return;
>     screenSelector=__dpmi_allocate_ldt_descriptors(1);
>     if (__dpmi_set_descriptor(screenSelector,selectorData)<0) abort();
> /*    ScreenContext.buffer.selector=screenSelector;*/
> }
> 
> -------------------------

Hmm, how would this be better than the dosmemput/get functions? (Sorry, 
I'm a new to pmode and this whole selector buisness is confusing)

Peace
===[ Gabo / [ABC] : gaminer AT undergrad DOT math DOT uwaterloo DOT ca ]===================
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