Path: utzoo!attcan!utgpu!jarvis.csri.toronto.edu!cs.utexas.edu!tut.cis.ohio-state.edu!pt.cs.cmu.edu!andrew.cmu.edu!mm3d+
From: mm3d+@andrew.cmu.edu (Matt McNally)
Newsgroups: comp.sys.mac.programmer
Subject: Why link with '-ad 4' ?
Message-ID: <oZReQbO00UhWQ1WF02@andrew.cmu.edu>
Date: 1 Dec 89 16:30:31 GMT
Organization: Computing Systems, Carnegie Mellon, Pittsburgh, PA
Lines: 27


I'm not sure it really matters, but here goes...

After looking at the MPW 3.0 default make files generated
with the 'Create Build Commands...' option I noticed that
the *new* default is to link with the '-ad 4' option.

Now I *think* I understand what the option does, as describe
in the MPW manuals but I have no idea WHY I would want to align
data to 4 byte (2 word) boundaries as opposed to single word 
(2 byte) boundaries.

Can anyone clarify this for me?  Should I re-link my older
programs using this option?  Does it have something to do
with different addressing modes across the 680x0 processors ?
What affects will using it (and its sister option '-ac n') have
on a application? 

Bewildered,


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 Matt M. McNally - 'Macintosh II Initiative' Research Programmer/Dugan
                    Carnegie Mellon, H&SS Dean's Office, Pittsburgh 15213
                    mm3d@andrew.cmu.edu | Baker Hall 369B, (412) 268-6990
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