hooks.c

#include <stdio.h>

// hook implementation
typedef void (*void_func_t)(void);
typedef struct tHookElem {
  unsigned int id; // dispatch id
  void_func_t func;
} HookElem;

#define HOOKLIST_STATIC_SIZE 20

typedef struct tHookList {
  size_t size;
  HookElem elems[HOOKLIST_STATIC_SIZE];
} HookList;

void initHookList(HookList* hl) {
  hl->size = 0;
}
void registerHook(HookList* hl, unsigned int id, void_func_t func) {
  size_t s = hl->size;
  hl->elems[s].id = id;
  hl->elems[s].func = func;
  hl->size = (s + 1) % HOOKLIST_STATIC_SIZE;
}
void dispatchHook(HookList* hl, unsigned int id) {
  unsigned int i;
  for (i = 0; i < hl->size; ++i) {
    if (id == hl->elems[i].id) 
      (*hl->elems[i].func)();
  }
}

void myTestHook1() {
  printf("hellow from hook 1\n");
}
void myTestHook2() {
  printf("hellow from hook 2\n");
}

int main(void) {
  unsigned int i;
  HookList hooks;
  initHookList(&hooks);
  registerHook(&hooks, 12, &myTestHook1);
  registerHook(&hooks, 2, &myTestHook2);

  for (i = 0; i < 13; ++i)
    dispatchHook(&hooks, i);
  
}