1. DLL Questions
I've been working on a Euphoria version of SWIG, and seem to be making good
progress. Basically, it will take a modified version of a C include file and
generate the C source for a DLL, the .DEF for the DLL, and a Euphoria
wrapper to automatically link and wrap all the functions in the DLL. This
makes it (in theory) fairly easy to link Euphoria to a pre-existing library.
I'm running into trouble when I try to create the DLL. I'm using lcc-win32
(a C compiler for Win32), and it is mangling the routine names. I'm hoping
someone on the list can give me a clue here.
My C file looks more or less like this:
#include <windows.h>
#include <math.h>
#include "junk.c"
BOOL WINAPI LibMain(HINSTANCE hDLL, DWORD Reason, LPVOID Reserved) {
// assume things go well
return TRUE;
}
The "junk.c" file looks like this:
int foo( int z ) { return z+100 };
int bar( int z ) { return z-100 };
and the .DEF file looks like this:
Library junk
EXPORTS
foo
bar
So far, so good; it compiles cleanly from the command line. I run into
trouble when I try to use the DLL. The names are mangled by adding an
underscore to the beginning of them:
_foo
_bar
If I adjust the Euphoria code to look for the mangled routine names, it
finds them, and they work fine. One way sround the name mangling is to
write:
Library junk
EXPORTS
foo=foo
bar=bar
But it seems a bit of a hack. Is this behavior normal? What's the proper way
to turn off the name mangling?
The point where I really run into trouble is when I try to include routines
from the standard include files. For example:
Library junk
EXPORTS
pow
Since pow() is declared as external in math.h, the dll *should* be able to
find it. The code compiles just fine, but when I go to link it, I get the
error:
Specified export _pow is not defined.
Missing exports. Program aborting.
The trick of adding:
pow=pow
to the .DEF file does not work here.
I suspect the problem is that lcc (the compiler) mangling the names, so when
lcclink (the dll linker) tries to resolve them, it can't find them in the
link table. But I can't find any command line options for lcc or lcclink
that seem to have any bearing on this.
Any suggestions?
Thanks!
-- David Cuny
2. Re: DLL Questions
David:
Are you aware that you can prevent name-magling to any C code
when you are using a CPP by using extern.
To do a whole include file do this.
extern "C" {
#include "aheader.h"
};
for a single function do this.
extern "C" {
int foo( );
}
Bernie
3. Re: DLL Questions
Bernie wrote:
> Are you aware that you can prevent name-magling
> to any C code when you are using a CPP by using
> extern.
Thanks; that should help. I hacked a solution by wrapping the routine again,
like this:
double wrap_foo( double bar ) {
foo( bar );
}
but your solution looks a lot better.
-- David Cuny
