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From: lsr@apple.UUCP (Larry Rosenstein)
Newsgroups: comp.sys.mac
Subject: Re: New master pointer query.
Message-ID: <6308@apple.UUCP>
Date: Mon, 21-Sep-87 19:57:44 EDT
Article-I.D.: apple.6308
Posted: Mon Sep 21 19:57:44 1987
Date-Received: Wed, 23-Sep-87 05:23:52 EDT
References: <3819@ecsvax.UUCP> <232@dbase.UUCP> <3841@ecsvax.UUCP>
Reply-To: lsr@apple.UUCP (Larry Rosenstein)
Organization: Advanced Technology Group, Apple Computer
Lines: 25

In article <3841@ecsvax.UUCP> wmcb@ecsvax.UUCP (William C. Bauldry) writes:
>
> Please don't shoot - i'm not really munging the bits...   
>The problem is: I'm passing a dereferenced handle as a parameter to
>an assembled routine - IM II (pg25) and the reference section to
>the MM chapter say use Lo3byte mask to strip off the high order byte

Inside Mac volume 5 describes a new trap called StripAddress to do this.
StripAddress will adn with Lo3Byte mask if the system is running in 24-bit
mode and will leave the address unchanged otherwise.

System 4.1 includes a patch to implement StripAddress on the Mac Plus.  If
the trap is not implemented (because the machine is not running System 4.1),
then you can do the masking yourself, since the machine must be in 24-bit
mode. 

-- 
Larry Rosenstein

Object Specialist
Apple Computer

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