Call back function

typedef int (*HandlerCB)(int a,void *b);

void RegisterHwEventCB(int xxx,HandlerCB  handlerCB);

以一般宣告來比較, 

1.int xxx;  宣告xxx為int型態

2.HandlerCB  handlerCB;  宣告handlerCB為HandlerCB 型態

int = int (*HandlerCB)(int a,void *b)

xxx = handlerCB

所以HandlerCB  handlerCB就等於int (*handlerCB)(int a,void *b)..

之後就可以直接把function傳進去RegisterHwEventCB ,用int (*handlerCB)(int a,void *b)接

這跟結構的typedef有點不一樣

typdef struct card Card;

則Card等於struct card.