Sender: nate AT cartsys DOT com
Message-ID: <36856987.61BC22E6@cartsys.com>
Date: Sat, 26 Dec 1998 14:56:07 -0800
From: Nate Eldredge <nate AT cartsys DOT com>
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To: djgpp AT delorie DOT com
Subject: Re: Calling C++ object member functions from assembly?
References: <3SCgHd$QOw AT cszone DOT cc DOT ntu DOT edu DOT tw>
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Reply-To: djgpp AT delorie DOT com

ªü­õ wrote:
> 
>         How can we call a C++ member function from assembly?
> 
>         For example:
> 
>         In C++:
> 
>                 class Merry {
>                 public:
>                         void CallMe();
>                 };
> 
>                 Merry Xmas;
> 
>         In assembly:
> 
>                 How to call Xmas.CallMe(); ?

There are two problems to be dealt with.

* Name mangling
In C++, names are mangled to encode the type of the symbol and allow
overloading.  So it may be called `MerryCallMe__voidfn__void' or
something equally cryptic.  You may have to look at the assembly to find
out what it is.

* Calling conventions
Member functions are often passed an invisible argument, which is (I
think) their `this'.  I think it's the first argument under GCC, but may
be wrong.  You'll have to pass it appropriately.

Can't you use the "C" attribute to specify C calling conventions and
naming, and write a wrapper function?  Or does that only work for
external functions?  I don't use C++ much.
-- 

Nate Eldredge
nate AT cartsys DOT com