c - Why does this execute a jump instruction? -

i have seen interesting c code in boot loader of small embedded product.

the code consists of 2 parts: boot loader , main code. start of main code address stored in function pointer. below code i'm talking about

typedef struct {   uint32_t myotherfield;   void (*maincodestartaddress)(void); } mystruct;  mystruct mystruct = {0x89abcdef, 0x12345678};  void main(void) {   // code   ...   mystruct.maincodestartaddress(); // jump start of application } 

i can't figure out why works? why machine go application code? appreciated.

the construct void (*maincodestartaddress)(void) declares function pointer named maincodestartaddress. point function taking no arguments , doesn't return anything.

you can assign function of same type function pointer, example:

void some_function(void) {     // useful }  mystruct.maincodestartaddress = some_function; 

then can call this:

mystruct.maincodestartaddress();  // same calling some_function(); 

in example fixed address assigned function pointer, when call function points jumps address , executes it.