#include <windows.h>
#include <stdio.h>


#define FUNCADDR 0x40000000

__declspec(dllexport) int test(void)
{
    // MOV EAX,FEEDBEEF
    // RETN
    unsigned char c[] = "\xB8\xEF\xBE\xED\xFE\xC3";  
    
    void *f = VirtualAlloc((void *) FUNCADDR, sizeof(c), MEM_RESERVE, PAGE_EXECUTE_READWRITE);
    if (f != (void *) FUNCADDR) {
        printf("can't alloc memory!\n");
        return 1;
    } 
    VirtualAlloc((void *) FUNCADDR, sizeof(c), MEM_COMMIT, PAGE_EXECUTE_READWRITE);
    memcpy(f, c, sizeof(c));
    FlushInstructionCache(GetCurrentProcess(), f, sizeof(c));
    

    unsigned (*fn)(void) = (void *) FUNCADDR;
    printf("by pointer variable: %08X\n", fn());
    
    printf("by pointer constant: %08X\n", ((unsigned (*)(void)) FUNCADDR)());

    return 0;
}