Xref: utzoo comp.arch:4875 comp.lang.c:10201
Path: utzoo!attcan!uunet!husc6!think!ames!pasteur!ic.Berkeley.EDU!faustus
From: faustus@ic.Berkeley.EDU (Wayne A. Christopher)
Newsgroups: comp.arch,comp.lang.c
Subject: Re: negative addresses
Message-ID: <3504@pasteur.Berkeley.Edu>
Date: 18 May 88 07:28:08 GMT
References: <10001@tekecs.TEK.COM> <2393@uvacs.CS.VIRGINIA.EDU> <21541@amdcad.AMD.COM> <1988May12.162906.16901@utzoo.uucp> <7881@brl-smoke.ARPA>
Sender: news@pasteur.Berkeley.Edu
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In article <10001@tekecs.TEK.COM>, andrew@frip.gwd.tek.com (Andrew Klossner) writes:
> >> Unfortunately, it is a real problem, because there are zillions of
> >> programs that implicitly assume that [null] pointers are all-zeros.
> 
> 		if (tbuf->c_ptr)

The trick here is that whenever a pointer is converted into an
integer (as here), the NULL pointer must be converted to the integer
0.  It doesn't matter what the bit pattern is before conversion.
Otherwise, as you say, the world would be swallowed up by huge
tidal waves and the sun would fall from the sky.  Are there any
implementations of C that use a non-0 bit pattern?  I pity the
compiler writer...

	Wayne