Path: utzoo!mnetor!uunet!lll-winken!lll-tis!ames!pasteur!ucbvax!hplabs!nsc!voder!apple!darin
From: darin@Apple.COM (Darin Adler)
Newsgroups: comp.sys.mac.programmer
Subject: Re: Pointer arithmetic in C w/ or w/o locked handles
Message-ID: <8542@apple.Apple.Com>
Date: 18 Apr 88 19:22:24 GMT
References: <1988Apr15.125337.100@mntgfx.mentor.com>
Reply-To: darin@apple.UUCP (Darin Adler)
Organization: Apple
Lines: 16
Keywords: pointer C arithmetic handles

In article <1988Apr15.125337.100@mntgfx.mentor.com> tomc@mntgfx.mentor.com (Tom Carstensen) writes:
> Is the problem I'm noticing with the following code
> fragment the compiler, or on error?
> ...
> The '8' (or 1000 binary) occurs because it is Locked - 
> (only on 68000 w/ 24 bit addressing).  but when I do
> pointer arithmetic, is the compiler messing up or 
> should I only add Locked handles or Unlocked handles
> together.

The solution to this is the StripAddress trap. It is used to strip any
bits from the high byte of a dereferenced handle. You can use it like this:

	pointer = StripAddress(*handle);
-- 
Darin Adler						AppleLink:Adler4
UUCP: {sun,voder,nsc,mtxinu,dual}!apple!darin	  CSNET: darin@Apple.com