linking gcc & vc++ object files

Mon Aug 3 09:05:00 GMT 1998

David Young asks:

> We are linking object files generated by gcc and object files  
> generated by vc++ on Windows-NT. In order to get object files  
> generated by gcc to link with object files generated by VC++ we have  
> to append a "@n" suffix (n seems to be always a multiple of 4) to the  
> function names (in the gcc related source files) whos object  
> definition is in the files generated by VC++. That's because the VC++  
> generates function symbols in object files with a "@n" suffix. Note,  
> this has nothing to do with C++ name mangling, all function  
> definitions are wrapped in extern "C" {} ; this is an ANSI-C related  
> issue.
> QUESTION: What is the "@n" all about?

This is just the first hurdle...

The @nn suffix means that the routine is compiled for "stdcall" calling 
procedures.  That is, the callee pops the arguments off of the stack.  The 
number after the `@' is the number of bytes that are popped off of the stack.

The other option (without the `@' suffix) is a caller-pops convention "cdecl"
type.  Depending on how various flags are set for VC++, it will default to
one or the other standards.  You can force a routine to be treated (either
in a function definition or external declaration) a particular way by adding
"stdcall" or "cdecl" to the function type specifier.  You really need to
make the functionality match, not just the name.

So, if you declare a function thusly:

stdcall int func(int a, char *b) { /* some code */ }

gcc should generate a callee pops function popping 8 bytes of arguments from
the stack named "func@8".

marcus hall
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