From:	Damian Yerrick <Bullcr_pd_yerrick AT hotmail DOT comRemoveBullcr_p>
Newsgroups:	comp.os.msdos.djgpp
Subject:	Re: SIGSEGV problem (disaster!)
Organization:	Pin Eight Software http://pineight.8m.com/
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References:	<8o64nq$s1q$1 AT nnrp1 DOT deja DOT com>
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NNTP-Posting-Date:	Fri, 25 Aug 2000 16:13:02 GMT
Distribution:	world
Date:	Fri, 25 Aug 2000 16:13:03 GMT
To:	djgpp AT delorie DOT com
DJ-Gateway:	from newsgroup comp.os.msdos.djgpp
Reply-To:	djgpp AT delorie DOT com

On Fri, 25 Aug 2000 15:52:36 GMT, jcditz AT my-deja DOT com wrote:

>I am currently writing a program for my senior
>Optical Physics research at svsu. Anyhow, I've
>got the program written (DJGPP of course), and it
>sure seems correct. At least, it compiles with no
>errors/warnings. The problem is, when I try to
>run it, it dumps a huge long nasty message:
>Exiting Due to signal SIGSEGV.
>stack fault at eip=000015d1
>and all the other stuff (values of the registers
>at the time and everything.

Right after it crashes, in the same DOS session, try running
  symify foo.exe
You'll get better results from symify if you specify the -g switch
(basic debugging information) to symify.

>I don't have an awful lot of experience
>programming in C, so I'm not sure what is wrong
>(at least the syntax is right).

SIGSEGV is most likely a general protection fault or something
similar.

>Using Turbo C++ 3.0 I get "stack overflow"
>messages when I try to run it. In Borland C++
>5.02 for Windows I get a "This program has
>performed an illegal operation and will be shut
>down" message which says it caused a "stack
>fault".

How much recursion are you using?  Try optimizing tail-recursion
into goto's.  (This is one of the rare "good uses" of goto, to
hand-optimize tail-recursion.)

>The only thing I should point out is that I'm using
>some really big arrays.
>I use about half a dozen doubles which are [61]
>[61][3]

Each of those is about 87 KB.  DJGPP's stack (used for automatic
variables and return addresses) is 512 KB by default; search the
FAQ list to find out how to change it.

>as well as one huge one
>int array [1281][1281];

This array is over 6 MB in size!

>Originally I was using Turbo C++ but when I got
>the error I figured it was just too much for a 16-
>bit compiler. Is it too much for a 32-bit
>compiler too?

Not if you dynamically allocate space for the array with malloc().

-- 
tiddly-day interj. (used to express agreement.)
  [American cellphone lingo]

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