Sometimes you create static C++ objects that require certain resources, such as a floating-point unit (FPU). You can check for these resources by creating a function called __PreInit__() which the compiler calls before it initializes static data. You cannot check for these resources in your main() routine, because the compiler initializes static data before it calls main().

You must declare the __PreInit__() function like this:

extern "C" void __PreInit__(void);

For example, this stub checks for a floating-point unit. In this case you would also have to define the functions HasFPU() and DisplayNoFPU() yourself.

#include <Types.h>
#include <stdlib.h>

extern "C" void __PreInit__(void);

void __PreInit__(void)
{
  if(!HasFPU())   {
    DisplayNoFPU();  // Display "No FPU" Alert
    abort();         // Abort program exection
  }
}