Path: utzoo!attcan!uunet!aplcen!haven!umd5!terminus.umd.edu!dzoey
From: dzoey@terminus.umd.edu (Joe I. Herman)
Newsgroups: comp.windows.ms
Subject: Re: Pleasures and Penanties of the Large Model
Message-ID: <7244@umd5.umd.edu>
Date: 5 Sep 90 17:16:57 GMT
References: <82934@aerospace.AERO.ORG>
Sender: news@umd5.umd.edu
Reply-To: dzoey@terminus.umd.edu (Joe I. Herman)
Organization: University of Maryland, College Park
Lines: 27

In article <82934@aerospace.AERO.ORG> slewis@aerospace.aero.org () writes:
>
>.................... there is a common assumption in most C's that there
>is only one type of pointer. Going to the large model forces all pointers to
>be far pointers (I think for this discussion we can ignore the differences in
>speed between accessing near and far pointers.). Forcing all pointers
>to be far pointers greatly simplifies the management of code.

There is also a common assumption in most C environments that
sizeof (int) == sizeof (char *).  This is true for small model
with the exception of those pointers explicitly declared far.
Luckly, a good compiler will usually catch this type of assumption,
but a good compiler also catches near/far pointer conversions.
Function protyping is an important tool in this.

Even though you want to ignore it, there is a noticable performance
hit in using far pointers over near pointers, especially on an
i486 (if what they say in comp.arch is true).  If possible I try
and stay away from far data pointers. 


			Joe Herman
			U. of Md.

dzoey@terminus.umd.edu
--
"Everything is wonderful until you know something about it."