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Message-ID:	<42C45145.4010202@familiehaase.de>
Date:	Thu, 30 Jun 2005 22:08:37 +0200
From:	"Gerrit P. Haase" <gerrit AT familiehaase DOT de>
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To:	cygwin <cygwin AT cygwin DOT com>
Subject:	undefined reference to `_CAPI_INSTALLED AT 0', why?
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Hello All,

I'm sure that this is covered somewhere, however I cannot find it
currently;)

Ok, I try to build a Cygwin application that requires CAPI functions
which are installed with the drivers for an ISDN card, the DLL is named
capi2032.dll, I have an import library which comes from the manufacturer
AVM but this contains symbols not included in the DLL or elsewhere.

In the .lib library are these symbols:

$ nm capi2032.lib | grep ' T '
00000000 T _CAPI_GET_MANUFACTURER AT 4
00000000 T _CAPI_GET_MESSAGE AT 8
00000000 T _CAPI_GET_PROFILE AT 8
00000000 T _CAPI_GET_SERIAL_NUMBER AT 4
00000000 T _CAPI_GET_VERSION AT 16
00000000 T _CAPI_INSTALLED AT 0
00000000 T _CAPI_MANUFACTURER AT 20
00000000 T _CAPI_PUT_MESSAGE AT 8
00000000 T _CAPI_REGISTER AT 20
00000000 T _CAPI_RELEASE AT 4
00000000 T _CAPI_WAIT_FOR_SIGNAL AT 4
00000000 T _TASK_REGISTER AT 12
00000000 T _TASK_RELEASE AT 4

in the import library I created are these symbols:

$ nm libcapi2032.dll.a | grep ' T '
00000000 T _TASK_RELEASE
00000000 T _TASK_REGISTER
00000000 T _CAPI_WAIT_FOR_SIGNAL
00000000 T _CAPI_SET_SIGNAL_FOR_16BIT
00000000 T _CAPI_RELEASE
00000000 T _CAPI_REGISTER
00000000 T _CAPI_PUT_MESSAGE
00000000 T _CAPI_MANUFACTURER
00000000 T _CAPI_INSTALLED
00000000 T _CAPI_GET_VERSION
00000000 T _CAPI_GET_SERIAL_NUMBER
00000000 T _CAPI_GET_PROFILE
00000000 T _CAPI_GET_MESSAGE_FOR_16BIT
00000000 T _CAPI_GET_MESSAGE
00000000 T _CAPI_GET_MANUFACTURER

Now linking against my import library gives me this errors:

Creating library file: .libs/libSimpleCapi.dll.a
.libs/capi20.o: In function `CAPI20_ISINSTALLED':
/p/ftproot/pub/asterisk/caiviar-0.3.5/src/capi20.c:68: undefined 
reference to `_CAPI_INSTALLED AT 0'
[...]


Where does the @0 in capi20.o: _CAPI_INSTALLED AT 0 came from?

I see in the source:

extern DWORD APIENTRY CAPI_INSTALLED (void);

unsigned CAPI20_ISINSTALLED (void) {
#if defined(CYGWIN) || defined(WIN32)
     return (unsigned)CAPI_INSTALLED () == 0;
#elif defined(LINUX)
     return capi20_isinstalled() == CapiNoError;
#endif


So why does the compiler creats a reference to _CAPI_INSTALLED AT 0 or
is it the linker who wants to resolve CAPI_INSTALLED with @0 attached.

Sure, I could edit my .def file and create an import library that 
contains the symbol names as expected by the linker, however I want
to know why this happens.

Is the docu around which explains it or can somebody who knows what
happens here tell me, please?


Gerrit
-- 
=^..^=

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