Path: utzoo!utgpu!water!watmath!clyde!att!osu-cis!tut.cis.ohio-state.edu!cwjcc!gatech!bbn!bbn.com!levin
From: levin@bbn.com (Joel B Levin)
Newsgroups: comp.sys.mac.programmer
Subject: Re: Segment Loader and Related Questions
Keywords: Segment loader, language interfaces, 32K limit
Message-ID: <29711@bbn.COM>
Date: 15 Sep 88 19:08:55 GMT
References: <369@ajpo.sei.cmu.edu>
Sender: news@bbn.COM
Reply-To: levin@BBN.COM (Joel B Levin)
Organization: BBN Communications Corporation
Lines: 28

_DATAINIT is documented at least a little in the MPW manual chapter
"Advanced programming tools" under "more about linking" and "segments
with special treatment".  See also the assembly manual under
"Programming for the Macintosh" in chapter 1.  There may be something
in the C manual, but I couldn't find it.  (These are the beta manuals;
the real ones are at home.)

The C syntax is:
  extern _DataInit ();
     . . .
  UnloadSeg (_DataInit);

Don't worry about the [not in ROM] stuff.  The libraries get it right.
In C you may have a choice of using the C interface or the Pascal
interface, depending on how you name routines.  If an argument is a
string, for instance, the Pascal interface avoids the c-string to
p-string conversion.  For Toolbox calls the Pascal version gets you an
in-line trap; for system calls that pass arguments by registers, you
get a different glue routine.  If you are using C, Earle Horton wrote
a nice set of definitions (originally to help with incompatibilities
between THINK C and MPW) which let you easily use the simpler Pascal
interface to the toolbox.  (let me know if you want a copy -- Earle
posted it once, so I guess I can distribute it :-)).

	/JBL

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