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From: res90@campus.swarthmore.edu
Newsgroups: comp.sys.mac.programmer
Subject: Re: MPW segmentation
Message-ID: <W27MRW5@cs.swarthmore.edu>
Date: 27 Jul 90 19:36:19 GMT
Sender: news@cs.swarthmore.edu (Usenet)
Organization: Swarthmore College
Lines: 40


I recieved several answers to my posting.

>I have been getting an error message 50 during linking.
>Jump table offset into code greater than 32K
> 
>I can't figure out what's up. Can anyone give me a hint.
> 

And a few requests for the answer. So if anyone is interested here goes.

My problem came about because I was not segmenting my code. The default
in MPW is to toss everything in one segment Main. Once this segment got 
above 32K I began to have trouble. The size problem alone can be corrected 
by using the -ss link option, but it turns out that there is a more 
fundemental problem in the jump offset. A function cannot begin at a 
location more than 32K into the code, because the jump-table entry is a 
signed 16-Bit value.
	In my case this whole mess could be solved by segmenting my code. 
Which turns out to be really trivial. In c 

#pragma segment name1
the code to go in segment name1 
#pragma segment name2
the code to go in segment name2

will place all the code following the #pragma segment name1 statement in a 
segment named name1, etc. This is explained well on page 11 of the MPW c manual.

	In pascal i'm told, though I have not tested it, that {$S name1}
will do the trick.
	There is i'm told some art to segmenting code. This is still lost 
on me but #pragma has kept me up and running.

Thanks To everyone

Rob Smith
Swarthmore College
Bitnet: RES90@SWARTHMR
Internet : RES90@CAMPUS.SWARTHMORE.EDU