How to declare assembly function with dynamic arguments in C++ like in C

Question

I have some C code and I want to port it to c++, the problem is that in C++ I can't use an assembly function due to it's dynamic use

C version

extern asmFunc(); // C function prototype version

//actual use example
asmFunc(var1,ptr2,HANDLE); 
asmFunc(ptr4,var2,NULL,eg ...); //everything works

C++ version

extern "C" VOID asmFunc(); // C++ function prototype version

//actual use example
asmFunc(var1,ptr2,HANDLE); // E0140 too many arguments in function call
asmFunc(ptr4,var2,NULL,eg ...); // E0140 too many arguments in function call

The Assembly function is declared in a separate asm file and it uses direct syscalls from ntdll.dll's functions, that's why it requires dynamic arguments

How to make it work?

Answer 1

Use ... in the argument list to specify the function is a variadic function taking unspecified arguments, eg:

extern "C" VOID asmFunc(...); // C++ function prototype version

//actual use example
asmFUNC(var1,ptr2,HANDLE);
asmFUNC(ptr4,var2,NULL,eg);