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Date: Mon, 3 Dec 2001 04:54:51 -0600
From: Lester Ingber <ingber AT ingber DOT com>
To: cygwin AT cygwin DOT com
Subject: anyone using 1.35 to prepare DLLs?
Message-ID: <20011203045451.A4356@ingber.com>
Reply-To: Lester Ingber <ingber AT ingber DOT com>
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I have had mixed results preparing DLLs to be called from Maple7 (an
algebraic software package) under Windows 2000.

I can get only as far as preparing a function without arguments,
based on a posting 14 Jun 00 by Carl Thompson:
    ------------8<------------ top cut -> bottom ------------->8------------
However, if foo() should go into a DLL, your files need to look like this:

   --- foo.c ---
   /* declaration (AKA prototype) of foo(), usually found in .h file */
   __declspec(dllexport) int foo(); /* exporting foo() from this DLL */

   /* definition of foo() */
   int foo() { return 1; }
   -------------

Make a DLL from foo.c:

   gcc -c foo.c -o foo.o
   gcc -Wl,--out-implib,libfoo.import.a -shared -o foo.dll foo.o

This will create the DLL (foo.dll) and the import library for the DLL   
(libfoo.import.a).
    ------------8<------------ bottom cut <- top ------------->8------------
I do not need to use libfoo.import.a to use foo.dll from Maple7.

I cannot get this to work if I change foo.c to
   --- foo.c ---
   __declspec(dllexport) int foo(int i);

   int foo(int i) { return (i + 10); }
   -------------

I've tried examples from some older postings, dating back to 1997 and
1998, but these do not seem to work out.

Is anyone using a current cygwin to prepare DLLs?

Thanks.

Lester


P.S.
I have a Sun PCi card in my Ultra10 running Windows 2000.  Unlike some
older cygwin I had a year or so ago, I could not get gcc to compile when
cygwin was installed on a shared Unix directory, though other software
runs fine this way.  However, when I installed cygwin on my D drive,
it seems to work fine.

-- 
 Prof. Lester Ingber  ingber AT ingber DOT com  ingber AT alumni DOT caltech DOT edu
 www.ingber.com                     www.alumni.caltech.edu/~ingber

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