| Re: IDL call_external and code distributed across several .so libraries [message #45794 is a reply to message #45698] |
Mon, 03 October 2005 05:15  |
Antonio Santiago
Messages: 201
Registered: February 2004
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Senior Member |
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Denis Barkats wrote:
> Hi, I am running IDL on a mac os X (10.3) and I was happy to have
> gotten the "call_external" function to work under IDL using the simple
> exemple described in Fanning's pages
> (http://www.dfanning.com/tips/calling_c.html). But I'd like to use
> call_external with pieces of codes distributed accross several
> libraries. Here is my exemple: I have two C codes, generic.c and
> utils.c( see below) and generic.c calls a function in utils.c.
>
> generic.c:
>
> int PowerOf2()
> {
> int output;
> output=someFunction();
> return output;
> }
>
> utils.c:
>
> int someFunction()
> {
> return 32;
> }
>
> Here is how I compile them
>
> gcc -c utils.c
This step "transforms" the C file to an "intermediate" format utils.o
> gcc -c generic.c
This has the same for generic.o
> ld generic.o -bundle -o generic.so
Now you are going to link, and so that you need the two *.o files.
The linker want to resolve symbols. That is the name "someFunction"
inside utils.c is a symbol that must be resolved. You need to provide
the two files so that linker now it.
This explanation is pretty poor but more or less this is the problem :)
> ld utils.o -bundle -o utils.so ( I get the following error here ld:
> Undefined symbols: _someFunction )
>
> Now how do I modify call_external to call PowerOf2, since it now
> depends on code in both generic.so and
> utils.so?
>
> IDL>
>
> print,call_external('/Users/denis/idl/bicep/generic.so','Pow erOf2',/i_value)
>
>
> Thank you
>
> Denis
>
--
-----------------------------------------------------
Antonio Santiago P�rez
( email: santiago<<at>>grahi.upc.edu )
( www: http://www.grahi.upc.edu/santiago )
( www: http://asantiago.blogsite.org )
-----------------------------------------------------
Grup de Recerca Aplicada en Hidrometeorologia (GRAHI)
Universitat Polit�cnica de Catalunya
Barcelona - SPAIN
-----------------------------------------------------
http://www.grahi.upc.edu
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