Path: utzoo!utgpu!watmath!clyde!att!rutgers!mailrus!cornell!uw-beaver!microsoft!w-colinp
From: w-colinp@microsoft.UUCP (Colin Plumb)
Newsgroups: comp.sys.amiga
Subject: Re: Problem with -b vs -b0 option on Lattice
Keywords: Lattice V4.01 V5.00 GURU
Message-ID: <96@microsoft.UUCP>
Date: 17 Dec 88 09:31:51 GMT
References: <29526@tut.cis.ohio-state.edu> <882@applix.UUCP>
Reply-To: w-colinp@microsoft.UUCP (Colin Plumb)
Distribution: na
Organization: Microsoft Corp., Redmond WA
Lines: 26
Confusion: Microsoft Corp., Redmond WA

In article <882@applix.UUCP> scott@applix.UUCP (Scott Evernden) writes:
|In article <29526@tut.cis.ohio-state.edu> erd@tut.cis.ohio-state.edu (Ethan R. Dicks) writes:
|>struct ExecBase *ExecBase, **EBase;
|>
|>EBase = (struct ExecBase **) (4L);
|>ExecBase = *Ebase;
| 
|        vs.
| 
|>       LEA     $4, A0
|>       MOVE    (A0), A6
| 
|These don't say the same thing.   Your C code suggests that location 4
|holds the address of a _pointer_ to ExecBase.  This isn't so- location 4 
|_is_ a pointer to ExecBase.
| 
|Try:
| 
|        struct ExecBase *ExecBase = (struct ExecBase *) 4;

Wrong!  The *contents* of location 4 are a pointer to ExecBase, but
"4", the number, is a pointer to a pointer to ExecBase.  The original
code is right.  Yours says the ExecBase structure starts at address 4,
which is not correct.
-- 
	-Colin (uunet!microsof!w-colinp)