Xref:	news2.mv.net comp.os.msdos.djgpp:605
From:	pausch AT electra DOT saaf DOT se (Paul Schlyter)
Newsgroups:	comp.os.msdos.djgpp
Subject:	Re: aligment / based pointers
Date:	27 Jan 1996 22:55:30 +0100
Organization:	Svensk Amat|rAstronomisk F|rening
Lines:	28
Message-ID:	<4ee70i$ite@electra.saaf.se>
References:	<960118222321_100662 DOT 3563_EHV63-1 AT CompuServe DOT COM> <4e74he$976 AT news DOT manawatu DOT gen DOT nz>
NNTP-Posting-Host:	electra.saaf.se
To:	djgpp AT delorie DOT com
DJ-Gateway:	from newsgroup comp.os.msdos.djgpp

In article <4e74he$976 AT news DOT manawatu DOT gen DOT nz>,
Malcolm Taylor <malcolm AT manawatu DOT gen DOT nz> wrote:
 
>>2. Does DJGPP-C understand based pointers ?
> 
> What is a based pointer?
 
It's Microsoft's way of declaring a C near pointer so that it uses
some other segment register than DS.  Usually SS is used instead.
 
This really only applies to segmented 16-bit code.  Since DJGPP
uses a 32-bit "flat" memory model, where all segment registers are
equal (with the possible exception of CS): all pointers are "near"
and "far" pointers does not exist.  They're not needed since 32-bit
addresses can cover all of addressable memory.
 
Thus, the concept of a "based pointer" is meaningless in DJGPP as
well as in any other environment using the "flat" memory model.
 
(in principle 32-bit code could be segmented too, but no environment
in use today uses 32-bit segmented code. The "flat" memory model
seems to have been universally accepted for 32-bit code on the x86).
 
-- 
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Paul Schlyter,  Swedish Amateur Astronomer's Society (SAAF)
Grev Turegatan 40,  S-114 38 Stockholm,  SWEDEN
e-mail:  pausch AT saaf DOT se        psr AT home DOT ausys DOT se

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