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Implement C++ functions using MASM

I have a class with a member function that I wish to implement using MASM.

class Foo

{

public:

    Foo() {}

    ~Foo() {}



    int adder(int, int); // <- This should be implemented using MASM

};

;ASM source

.486

.model flat, stdcall

option casemap :none



.code



adder proc arg1:dword, arg2:dword

        mov eax, arg1

        add eax, arg2



        ret



adder endp



end

I know how to implement C function, but now C++. I have read this http://www.codeproject.com/cpp/Using...nesVisualC.asp but with no success. How, and where, do I declare the function? Something like

extern "C" int __stdcall adder(int, int);

or similiar should be somewhere I guess...

int main()

{

    Foo foo = Foo();

    foo.adder(1, 2);

}

This does not work, cause I don't know how to declare the function. Anyone who can help me out with this?

/Thanks for your help!

/Klarre

Try declaring it right after including headers.

Tried this

#include "foo.h"

extern "C" int __stdcall adder(int, int);

#include <iostream>



int main()

{

        Foo foo = Foo();

        std::cout << foo.adder(4, 5) << std::endl;



        system("pause");



        return 0;

}

Visual Studio gave me this compiler error:

error C2039: 'adder' : is not a member of 'Foo'

Where are you doing anything to associate the definition with the class? :confused:

This is a bit tough and won't be portable, but its not impossible. First you need to understand what exactly a member function is compiled to, then you emulate that with your ASM function. Important things to know are how the name mangling works or not forgetting that VC passes an implicit this pointer to member functions.

I think your best bet is to write the function in C++, compile into debug code, open that up in a debugger to see what exactly VC expects the function to be called and copy that together with the calling convention in your ASM code.

Also check out the Agner Fog's Manuals.

Quote:

won't be portable

LOL!!

Are you laughing at the fact that Assembly is not portable? If so, very fair point :) . I ment though that a solution wouldn't be portable across different C++ compilers, even on identical architectures.

Actually Klarre, forgot to ask you an important question, why do you want to be able to write meber functions in ASM? Its easier to write stdcall or ccall ASM functions, build them into an object file or library, link that into your C++ app and then call those functions from inside member, or indeed any, functions.

Yeah, no offense, it just tickled my funnybone when I read it.

Quote:

Originally Posted by Eoin

Actually Klarre, forgot to ask you an important question, why do you want to be able to write meber functions in ASM? Its easier to write stdcall or ccall ASM functions, build them into an object file or library, link that into your C++ app and then call those functions from inside member, or indeed any, functions.

I am just curious about how it works!

I finally got it linked correctly.

class Foo

{

public:

        Foo();

        ~Foo();



        int bar();

};



int main()

{

        Foo foo = Foo();

        int x = foo.bar();



        return 0;

}

.386P



; ----------------------------------------------------------------------------

; Foo::Foo()

; ----------------------------------------------------------------------------

_TEXT SEGMENT

??0Foo@@QAE@XZ PROC NEAR

        mov eax, ecx

        ret 0



??0Foo@@QAE@XZ ENDP

_TEXT ENDS



; ----------------------------------------------------------------------------

; Foo::~Foo()

; ----------------------------------------------------------------------------

_TEXT SEGMENT

??1Foo@@QAE@XZ PROC NEAR

        ret 0



??1Foo@@QAE@XZ ENDP

_TEXT ENDS



; ----------------------------------------------------------------------------

; int Foo::bar()

; ----------------------------------------------------------------------------

_TEXT SEGMENT

?bar@Foo@@QAEHXZ PROC NEAR

        mov eax, 4

        ret 0



?bar@Foo@@QAEHXZ ENDP

_TEXT ENDS



END

So now is the next step to play around with variables and other complex stuff.

Thanks alot for your help! See you soon again! ;)

/Klarre