Date: Thu, 15 Feb 1996 14:47:47 -0800 (GMT)
From: Orlando Andico <oandico AT eee DOT upd DOT edu DOT ph>
To: DJGPP Mailing List <djgpp AT delorie DOT com>
Subject: Strange Errors
Message-ID: <Pine.SOL.3.91.960215143916.2418A-100000@gollum>
MIME-Version: 1.0

Hi everyone:

I have a strange error to relate. I got a copy of SUSAN (this is a 
low-level image-processing program). The author claims that it works 
under DJGPP (didn't specify the version though). I _have_ compiled it 
with GCC 2.6.3 under Solaris 2.3, and it works as advertised. However, 
using DJGPP 2.0 and GCC 2.7.2, the strangest errors occur.

Here's the stack trace (compiled with gcc -g -o susan.exe susan.c -lm)


Exiting due to signal SIGSEGV
Page fault at eip=000106b1, error=0006
eax=000000af ebx=000107b0 ecx=00000010 edx=0005d1c0 esi=000107b0 edi=000005b0
ebp=00003474 esp=00003474 cs=00a7 ds=00af es=00af fs=008f gs=00bf ss=0033
Call frame traceback EIPs:
  0x000106b1   ___djgpp_exception_table+281


Another odd thing: the above stack trace appeared only when I tried to do 
something (detect some edges off a PGM file). If I just type ``susan'' 
with no parameters (this is supposed to display some usage options), the 
usage gets displayed, as expected.

HOWEVER: if I compile like this:

  gcc -Ox -o susan.exe susan.c -lm

(I've tried optimization levels 2 and 3) *the program always bombs*.
That is, even attempting to just print out the usage causes a 
segmentation fault similar to that I've included above. The fault always 
occurs in the ___dgjpp_exception_table thing (at varying offsets, due to 
the changing file size), whatever that is.

The program seems to be a memory hog, but I have enough memory (16MB, 
100MB+ of swap, CWSDPMI production(?) version). I've tried this on two 
computers, a P100 and a 486DX2-66, with the same results.

Any ideas would be appreciated.

-- Orly

/--------------------------------------------------------------------------\
|  Orlando A. Andico               "I have no concept of time, other than  |
|  oandico AT eee DOT upd DOT edu DOT ph             it is flying." -- Alanis Morissette  |
\--------------------------------------------------------------------------/