[fpc-pascal] Help needed with interfacing to C-object-files.

Koenraad Lelong fpascal at brouwerij.homelinux.net
Thu Mar 10 21:21:38 CET 2005

Marc Santhoff wrote:
> Am Di, den 08.03.2005 schrieb Koenraad Lelong um 21:51:
>>Marc Santhoff wrote:
>>>Am Mo, den 07.03.2005 schrieb Koenraad Lelong um 22:36:
>>>>I'm trying to make an interface to a kind of library, but I'm stuck. Any 
>>>>pointers are welcome.
>>>>There is a C-header file, but this is common for a number of C-modules. 
>>>>If I translate (h2pas) this file, and use it, the linker tries to find 
>>>>an o-file, which does not exist. Any suggestions how to handle this ?
>>>You've got to compile the C files to .o (gcc -c thesource.c) and then
>>>link them into your pascal unit ({$L thesource.o}). This way it should
>>>work, I'm using some C stuff like that.
>>Let me explain more : the header file is used in at least five 
>>source-files, so compiling gives (at least) five .o files, but none with 
>>the name of the header-file.
>>I was thinking that splitting that header-file in smaller files, each 
>>for its own source could do the trick, but I'll have to check this 
>>carefully. I had hoped for another suggestion.
>>Anyway, thanks for the response.
> Hm, I don't know, how the translated header looks in pascal, but if it's
> a complete unit itself you could try to {$L xxx} all resulting .o files
> in that unit. So any declared function and type should be found ... the
> other thing would be, if the sources from the 1-wire stuff form a
> dynamic library, then you simply have to tell the linker to pull this
> lib (.so) in
> fpc -k-l<thelibraryname without the.so-ending> ...
> should work and does for me, too. Or it needs an additional
> "-k-L/the/path/to/1-wire-lib". The only thing in your sources is to put
> the translated header in the uses clause.
> HTH,
> Marc
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I should appologise. I don't know how it happened, maybe sand in my eyes 
;-), but I seem to have misread the output. It wasn't ownet.o it didn't 
find, but ownetu.o. When I saw this I realised there had to be something 
wrong about my linking string. And indeed it was. After correcting this 
linking went fine, except for a huge number of errors. After including 
more o-files in ownet.pp, these were resolved.
Now I have only about 10 errors, in the main program. I'm working to 
resolve these.
What I did want to ask is this : I mentioned adding more o-files in 
ownet.pp. The files I had to add are used in the first o-files I 
included, e.g. in ownetu.c ds2480.h/ds2480.c are used, so when I 
included {$L ds2480.o} in ownet.pp the errors of ownetu disappeared.
My question : is the linker not smart enough to find out by itself where 
to look for those missing object files ?
Is there a way I can avoid this ?
I hope I'm not making a fool of myself any more than I did already ;-).

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