Coercion type conversions in a function declaration

How do I write a program that allows the microprocessor to automatically invoke a subroutine at the 0 position at startup?

The first thing we need to do is to find a place where a pointer is pointing at that position, and that position is just another function of any type we need, then the problem can be solved. Let's say we have a function pointer to that location whose type is empty. such as: (*FP) (). The most important question now is how to make the FP point at the 0 position.

We think of a type of coercion. For example, the integer 0 is converted to a pointer to a function of the null type (void (*) ()) 0, which means exactly the same as the FP type, and our purpose is to replace the FP with it.

So this code can be written ((void (*) ()) 0) ().

Coercion type conversions in a function declaration