[MinGW-cvs] htdocs mingwfaq.shtml,1.34,1.35

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Update of /cvsroot/mingw/htdocs
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Modified Files:
	mingwfaq.shtml 
Log Message:
Add MSVC/MinGW interlink FAQ.

Index: mingwfaq.shtml
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RCS file: /cvsroot/mingw/htdocs/mingwfaq.shtml,v
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retrieving revision 1.35
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        <li><a href="#faq-w32api">What is w32api?</a></li>
        <li><a href="#faq-comsupport">Is support provided for COM?</a></li>
+       <li><a href="#faq-msvcdll">How can an MSVC program call a MinGW DLL, and vice versa?</a></li>
        <li><a href="#faq-cross">How can I build a cross compiler?</a></li>
        <li><a href="#faq-bugreports">How can I report bugs?</a></li>
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           progress to improve support.  Check the MinGW mailing list archives
           for more details on COM and more links to example files.
+       </p>
+       <p><a href="#index">Back to index</a></p>
+ 
+       <hr />
+ 
+ 
+ 
+       <a name="faq-msvcdll" />
+       <h3>How can an MSVC program call a MinGW DLL, and vice versa?</h3>
+       <p>
+         Assume we have a testdll.h, testdll.c, and testmain.c.  In the first case,
+         we will compile testdll.c with MinGW, and let the MSVC-compiled testmain
+         call it.  You should use
+         <blockquote>
+         <code>gcc -shared -o testdll.dll testdll.c \<br />
+         &nbsp;&nbsp;&nbsp; -Wl,--output-def,testdll.def,--out-implib,libtestdll.a</code>
+         </blockquote>
+         to produce the DLL and DEF files.  MSVC cannot use the MinGW library, but
+         since you have already the DEF file you may easily produce one by the Microsoft
+         <code>LIB</code> tool:
+         <blockquote>
+           <code>lib /machine:i386 /def:testdll.def</code>
+         </blockquote>
+       </p>
+       <p>
+         Once you have testdll.lib, it is trivial to produce the executable with
+ MSVC:
+         <blockquote>
+           <code>cl testmain.c testdll.lib</code>
+         </blockquote>
+       </p>
+       <p>
+         Now for MinGW programs calling an MSVC DLL.  We have two methods.  One way
+         is to specify the LIB files directly on the command line <em>after</em> the
+         main program.  For example, after
+         <blockquote>
+           <code>cl /LD testdll.c</code>
+         </blockquote>
+         use
+         <blockquote>
+           <code>gcc -o testmain testmain.c testdll.lib</code>
+         </blockquote>
+       </p>
+       <p>
+         The other way is to produce the .a files for GCC.  For <code>__cdecl</code>
+         functions (in most cases), it is simple: you only need to apply the <code>reimp</code>
+         tool from Anders Norlander (since his web site is no longer available, you may choose
+         to download <a href="http://mywebpage.netscape.com/yongweiwu/reimp_new.zip">here</a>
+         a version enhanced by Jose Fonseca):
+         <blockquote>
+           <code>reimp testdll.lib</code><br />
+           <code>gcc -o testmain testmain.c -L. -ltestdll</code>
+         </blockquote>
+       </p>
+       <p>
+         However, for <code>__stdcall</code> functions, the above method does not work.
+         For MSVC will prefix an underscore to <code>__stdcall</code> functions while
+         MinGW will not.  The right way is to produce the DEF file using the
+         <code>pexports</code> tool from
+         <a href="http://www.is.lg.ua/~paul/devel/binutils.html">http://www.is.lg.ua/~paul/devel/binutils.html</a>
+         and filter off the first underscore by <code>sed</code>:
+         <blockquote>
+           <code>pexports testdll.dll | sed "s/^_//" &gt; testdll.def</code>
+         </blockquote>
+         Then, when using <code>dlltool</code> to produce the import library, add
+         `<code>-U</code>' to the command line:
+         <blockquote>
+           <code>dlltool -U -d testdll.def -l libtestdll.a</code>
+         </blockquote>
+         And now, you can proceed in the usual way:
+         <blockquote>
+           <code>gcc -o testmain testmain.c -L. -ltestdll</code>
+         </blockquote>
+         Hooray, we got it.
        </p>
        <p><a href="#index">Back to index</a></p>