Static library

You could use absolute jump addresses in your app. But if you find an error in the middle tier so you need to fix it, then all function addresses might change and the released applications must be recompiled.

With a pointer table - just a struct or array with pointers stored at a fixed address - the app doesn't need to care about changed addresses in the middle tier. All it cares about is the pointer table and that the function pointers continues to have the same calling conventions and input/output signatures.

You could use absolute jump addresses in your app. But if you find an error in the middle tier so you need to fix it, then all function addresses might change and the released applications must be recompiled.

With a pointer table - just a struct or array with pointers stored at a fixed address - the app doesn't need to care about changed addresses in the middle tier. All it cares about is the pointer table and that the function pointers continues to have the same calling conventions and input/output signatures.

Hi Westermark,

With a pointer table - just a struct or array with pointers stored at a fixed address - the app doesn't need to care about changed addresses in the middle tier. All it cares about is the pointer table and that the function pointers continues to have the same calling conventions and input/output signatures.

I understand this struct/arry is located to an absolut address in the middle region but how is it initialized? Is correct this initialization from the middle region and how the firmware is getting the pointer table?

//******************
// Middle region
//******************

struct PointerTable{
  int (*foo)(void);
  void (*bar)(void);
};
int foo(void);
void bar(void);

int foo (void){
  // ...
}

int foo (void){
  // ...
}

// Inizialize pointer table struct at 0x80100005
const struct PointerTable pt = {foo, bar} __at__ 0x8010005;

//******************
// App region
//******************
struct PointerTable{
        int (*foo)(void);
        void (*bar)(void);
};




struct PointerTable pt __at__ 0x8010005;        // Middle region address




pt.foo();
pt .bar();

Thank you very much for your help