Relay-Version: version B 2.10 5/3/83; site utzoo.UUCP
Path: utzoo!mnetor!seismo!husc6!think!ames!ucbcad!ucbvax!decvax!tektronix!tekgen!tekigm2!phils
From: phils@tekigm2.TEK.COM (Philip E Staub)
Newsgroups: comp.sys.amiga
Subject: Re: Manx 3.4 bug and sc.c
Message-ID: <1777@tekigm2.TEK.COM>
Date: Mon, 18-May-87 17:03:42 EDT
Article-I.D.: tekigm2.1777
Posted: Mon May 18 17:03:42 1987
Date-Received: Tue, 19-May-87 06:38:13 EDT
References: <56@f.gp.cs.cmu.edu>
Reply-To: phils@tekigm2.UUCP (Philip E Staub)
Organization: Tektronix, Inc., Beaverton, OR.
Lines: 43

In article <56@f.gp.cs.cmu.edu> mjw@f.gp.cs.cmu.edu (Michael Witbrock) writes:
>I was using someone's Manx compiler to compile the fractal terraion
>generator sc.c (which, incidentally just guru'd when I tried to run it..)
>anyway, it has a line
>
>short Cell[COUNT][COUNT];
>
>in it (a global). This compiles, but is an undefined symbol at link time.
>Changing the line to 
>
>static short Cell ....
>
>fixed this.

I found another "fix" for this. What appears to be happening is that since
COUNT is defined as (1<<SIZE) and SIZE is defined as 8, this winds up being
Cell[256][256], which results in a data structure size of 65536.
(Interesting number, eh? Translation: 0 for 16 bit ints. Read on.)
The resulting declaration in the assembly language file was:

	global	_Cell,0

(Or something similar. I don't remember exactly). The important part is the
length of the data area which is generated. When I changed SIZE to 7,
(Cell[128][128] = 32768) I got 

	global	_Cell,32768

as expected. (Sorry, I didn't try going the other way)

I suspect that there are two different grammar productions which result in
the code generated by the "short Cell[][]" and "static short Cell[][]" 
declarations, with the former being broken, and the latter being functional.

Any comments from someone closer to the compiler source?


Phil
-- 
-------------------------------------------------------------------------------
Phil Staub              tektronix!tekigm!phils    (206) 253-5634
Tektronix, Inc., ISI Engineering
P.O.Box 3500, M/S C1-904, Vancouver, Washington  98668