Calling function pointers without definitions

int (*func)(int arg1,char* fedup,int keeptypingmyarguments);

struct Passer {
    int args[13]; //52 bytes of argument stack space
    int pos; //Stack position (0 is 1st arg, 1 is 2nd arg, etc.) *Can be a char to save space
};

typedef int (*FUNC)(Passer pass);
FUNC func = ptr_to_func;

#include <windows.h>
struct Passer {
    int args[13];
    int pos;
};
typedef int (*FUNC)(Passer pass);
FUNC func;
int main() {
    Passer pass;
    func = (FUNC)GetProcAddress(LoadLibrary("kernel32.dll"),"Beep");
    pass.args[0] = 1500;
    pass.args[1] = 500;
    func(pass);
    Sleep(100);
    func({{1500,500}}); //You don't even need to declare a Passer variable, just note the two pairs of {}s
}

1500
500
uninitialized 
uninitialized 
uninitialized 
uninitialized 
uninitialized 
uninitialized 
uninitialized 
uninitialized 
uninitialized 
uninitialized 
uninitialized 
uninitialized

enum CALLINGCONV
{
	CALLINGONV_STDCALL,
	CALLINGCONV_CDECL,
	CALLINGCONV_THISCALL, 
	CALLINGCONV_FASTCALL,
};

int callsomething(void* func, CALLINGCONV cc, int* args, unsigned int count)
{
	int retval;

	if (cc == CALLINGCONV_THISCALL && count < 1) return 0; //__thiscall function must have at least one parameter (this pointer)

	__asm
	{
		push ecx;                                 //save original values
		push esi;
		push edi;

		push eax;                                 //calculate stack size
		mov eax, 4;
		mov ecx, count;
		mul ecx;
		mov ecx, eax;
		pop eax;

		sub esp, ecx;                             //put parameters on stack
		mov esi, args;
		mov edi, esp;
		rep movs [edi], byte ptr [esi];

		cmp cc, CALLINGCONV_THISCALL;             //check if calling convention was __thiscall
		jne not_thiscall;

		pop ecx;                                  //remove first parameter from stack and put it on ecx

not_thiscall:
		cmp cc, CALLINGCONV_FASTCALL;             //check if calling convention was __fastcall
		jne neither;

		mov esi, count;                           //check parameter count
		cmp esi, 1;                               //make sure we have 1 parameters or more
		jl neither;

		pop ecx;                                  //remove first parameter from stack and put it on ecx

		mov esi, count;	                          //check parameter count
		cmp esi, 2;                               //make sure we have 1 parameters or more
		jl neither;

		pop edx;                                  //remove second parameter from stack and put it on edx

neither:
		call func;                                //lets call the function
		mov retval, eax;                          //save return value

		cmp cc, CALLINGCONV_CDECL;                //if calling convention was __cdecl, perform a stack clean up
		jne not_cdecl;
		push eax;
		mov eax, 4;
		mov ecx, count;
		mul ecx;
		mov ecx, eax;
		pop eax;
		add esp, ecx;

not_cdecl:
		pop edi;                                  //restore original values
		pop esi;
		pop ecx;
	}
	return retval;
}

void hey(int arg1, int arg2, int arg3, int arg4) //default calling convention is __cdecl
{
	cout << arg1 << ",  " << arg2 << ",  " << arg3 << ",  " << arg4 << endl;
}

void __fastcall hey2(int arg1, int arg2, int arg3, int arg4)
{
	cout << arg1 << ",  " << arg2 << ",  " << arg3 << ",  " << arg4 << endl;
}

class myclass
{
public:
	int arg1;
	void hey3(int arg2, int arg3, int arg4) //this one should be __thiscall
	{
		cout << arg1 << ",  " << arg2 << ",  " << arg3 << ",  " << arg4 << endl;
	}
};

//you cant convert &myclass::hey3 to void*, so i came up with this trick..
struct hack 
{
	typedef void (myclass::*myfunc)(int,int,int);
	myfunc pp;
};

int main() 
{
	FARPROC func = GetProcAddress(LoadLibraryA("kernel32.dll"), "Beep");

	myclass my;
	my.arg1 = 5;
	hack hk;
	hk.pp = &myclass::hey3;

	int beeparg[2] = {1500, 500};
	int myargs[4] = {5, 10, 51, 11};
	int thisargs[4] = {(int)&my, 10, 51, 11};
	
	callsomething((void*)func, CALLINGONV_STDCALL, beeparg, 2);
	callsomething((void*)hey, CALLINGCONV_CDECL, myargs, 4);
	callsomething((void*)hey2, CALLINGCONV_FASTCALL, myargs, 4);
	callsomething((void*)(*(int*)(&hk)), CALLINGCONV_THISCALL, thisargs, 4);
}