Xref:	news2.mv.net comp.os.msdos.djgpp:7685
From:	"John M. Aldrich" <fighteer AT cs DOT com>
Newsgroups:	comp.os.msdos.djgpp
Subject:	Re: buffer -> screen transfers
Date:	Tue, 20 Aug 1996 20:00:24 -0700
Organization:	Three pounds of chaos and a pinch of salt
Lines:	23
Message-ID:	<321A7BC8.27F4@cs.com>
References:	<320647A3 DOT 5827 AT cadvision DOT com> <3209b332 DOT 21898266 AT news DOT wolfe DOT net> <32141C89 DOT 5DB5 AT gbrmpa DOT gov DOT au> <4vd0s1$m76 AT ursa DOT smsu DOT edu>
NNTP-Posting-Host:	ppp211.cs.com
Mime-Version:	1.0
To:	"Tony O'Bryan" <root AT ursa DOT smsu DOT edu>
DJ-Gateway:	from newsgroup comp.os.msdos.djgpp

Tony O'Bryan wrote:
> 
> Will __crt0_nearptr_enable allow a pointer to linear address 0xa0000 to
> directly access the video screen?

Yes, but you have to reference all your direct memory writes with
__djgpp_conventional_base to get the *correct* pmode address to write to.
So, the correct address for the VGA screen would be the following:

char *VGAscreen = (char *) (0xA0000 + __djgpp_conventional_base);

Read the description of the __djgpp_nearptr_enable() function for more
info, including a complete example (using the text screen, but the
technique is the same).

John

-- 
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| John M. Aldrich, aka Fighteer I     |       fighteer AT cs DOT com              |
| Proud owner of what might one day   |  Plan: To make Bill Gates suffer   |
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