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From: "Crist J. Clark" <cjc@cc942873-a.ewndsr1.nj.home.com>
Message-Id: <199912132312.SAA74814@cc942873-a.ewndsr1.nj.home.com>
Subject: Back to the FORTRAN Question
To: freebsd-questions@FreeBSD.ORG (FreeBSD Questions)
Date: Mon, 13 Dec 1999 18:12:39 -0500 (EST)
Reply-To: cjclark@home.com
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My f2c FORTRAN problems are still haunting me (see thread 'FORTRAN
Error Question' from November). This time, however, I think I have
more of an idea what is going on.

I get the following error when it comes to linking object files
produced by f77,

slamshk.o(.data+0x0): multiple definition of `rshock_'
slaminz.o(.data+0x1e8): first defined here
*** Error code 1

Stop.

If I do f2c conversions and examine the C code, see that slamshk.c has
the following, 

struct {
    integer fill_1[1];
    real e_2;
    integer fill_3[158];
    } rshock_ = { {0}, (float)8.314e7 };

And slaminz.c has,

struct {
    integer fill_1[44];
    real e_2[2];
    integer fill_3[19];
    real e_4[19];
    integer fill_5[76];
    } rshock_ = { {0}, (float)4., (float)1., {0}, (float)0., (float).1, (
            float).2, (float).3, (float).4, (float).5, (float).6, (float).7, (
            float).8, (float).9, (float)1., (float)1.25, (float)1.5, (float)
            1.75, (float)2., (float)3., (float)4., (float)5., (float)6. };

Both contain the following code before these declarations,

struct rshock_1_ {
    real <stuff deleted>
};

#define rshock_1 (*(struct rshock_1_ *) &rshock_)

I understand why the linker is choking on this. Both of these
declarations for rshock_ have global scope.

In FORTRAN, RSHOCK is a common block in a file, slamshk.cmn,

      COMMON/RSHOCK/<stuff deleted>

And it appears in both slamshk.f and slaminz.f via,

      INCLUDE 'slamshk.cmn'

Lines.

It seems the original authors of this FORTRAN code definately did not
write it with f2c in mind. However, I assume f2c is meant to handle
common blocks. How do I rearrange the code and the f77 commands to get
f77 to understand how to handle common blocks as common among several
files/routines? Is there an online tutorial somewhere about how to
write or modify FORTRAN code to get f77/f2c to handle it correctly?
Offhand I would think f77 should have to understand how to treat common
blocks something like C extern's.

Thanks for any help.
-- 
Crist J. Clark                           cjclark@home.com


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