Sender: fabrice AT asim DOT lip6 DOT fr
Message-ID: <3459CE68.390E@trash.lip6.fr>
Date: Fri, 31 Oct 1997 13:26:16 +0100
From: Fabrice ILPONSE <fabrice AT asim DOT lip6 DOT fr>
MIME-Version: 1.0
To: djgpp workers group <djgpp-workers AT delorie DOT com>
Subject: flat pointer
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Hi!

from the users list:



-- 
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	+-+-+	Fabrice ILPONSE
	  |	<fabrice AT asim DOT lip6 DOT fr>
	  |
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	  -
Fabrice ILPONSE wrote:
> 
>         I am thinking about adding another kind of pointer in djgpp.
>         In djgpp, the pointers are flat but the lowest adress is limited by the
> DS selector.
>         Why not use a "<type> flat *" in djgpp that would make easier to access
> the < 640Ko memory for the video memory for example.
>         The code would be the same as the normal pointers except that the
> generated code will be :
>                 - movl %gs:(?,?,?),?
>         rather than
>                 - movl (?,?,?),?
> 
>         I think GS is already set to the physical adress 0000:0000 (in RM)
>         This kind of pointer is very dangerous and certainly reserved to expert
> user that know what they do.
> 
>         It would be possible to assign normal pointers to flat by adding the DS
> base adresse to the offset but in the other sens it would be more
> "hazardious".
> 
 

>         What's your mind about that?