> I have problem using external shared object on=20
> IBM AIX version: 4.3 with=20
> NCL version: 4.1
>
> A simple sample fortran code :
>
> ---------------- test.f -----------------------
> C NCLFORTSTART
> SUBROUTINE TEST(A,B)
> INTEGER A,B
> C NCLEND
> A =3D B + 2
> END
>
> -------- Make a shared object by: ---------
> wrapit77 < test.f > test_W.c
> nhlcc -c test_W.c -I$NCARG_ROOT/include -L$NCARG_ROOT/lib
> nhlf77 -c test.f
> ld -G -bnoentry -bexpall -o test.so test.o test_W.o
>
> ---------- run ncl will get: -------------------
> $ncl
> ncl 0>external test "./test.so"
> Illegal instruction(coredump)
> $
>
> Anyone has any idea ? I have tried it on Linux and it worked.
Dear Cheung Ping,
It looks like you are doing everything correctly. But, before I
attempt to debug the problem, I'd like to point out a very useful
script called "WRAPIT". This script does all of the steps of creating
an NCL shared object for you. It figures out what kind of system you
are on, calls wrapit77, compiles both the Fortran and C files, and
runs the appropriate "ld" command. All you have to do is give it the
Fortran file with the appropriate NCLFORTSTART and NCLEND statements
in it, and it will produce a ".so" file for you.
For example, with your "test.f" file, you can do the following:
WRAPIT test.f
and it will produce a "test.so" file. Please try this and see if it
fixes your problem.
Meanwhile, if you want to continue to create the shared object by
hand, you need to make sure you use either the 32-bit or 64-bit
compiler across the board. Whichever one you are using, you should
specify this on the "ld" line as follows:
32-bit:
ld -b32 -G -bnoentry -bexpall -o test.so test.o test_W.o
64-bit:
ld -b64 -G -bnoentry -bexpall -o test.so test.o test_W.o
This may not fix your problem, but it's a start. Also, you don't need
to include "-I$NCARG_ROOT/include -L$NCARG_ROOT/lib" on the "nhlcc"
compile line because "nhlcc" should already be including these for
you.
In any case, I highly recommend trying the WRAPIT script. It works
under Solaris, IRIX64, AIX, DUNIX, and the Linux operating systems.
If you download the latest version of NCAR Graphics, you should have
access to this script in $NCARG_ROOT/bin.
Cheers,
--Mary Haley
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