Function luaH_getint

lib/lua/src/ltable.c:745–767

** Search function for integers. If integer is inside 'alimit', get it ** directly from the array part. Otherwise, if 'alimit' is not ** the real size of the array, the key still can be in the array part. ** In this case, do the "Xmilia trick" to check whether 'key-1' is ** smaller than the real size. ** The trick works as follow: let 'p' be an integer such that ** '2^(p+1) >= alimit > 2^p', or

** if cannot be smaller than alimit.
*/
const TValue *luaH_getint (Table *t, lua_Integer key) {
  lua_Unsigned alimit = t->alimit;
  if (l_castS2U(key) - 1u < alimit)  /* 'key' in [1, t->alimit]? */
    return &t->array[key - 1];
  else if (!isrealasize(t) &&  /* key still may be in the array part? */
           (((l_castS2U(key) - 1u) & ~(alimit - 1u)) < alimit)) {
    t->alimit = cast_uint(key);  /* probably '#t' is here now */
    return &t->array[key - 1];
  }
  else {  /* key is not in the array part; check the hash */
    Node *n = hashint(t, key);
    for (;;) {  /* check whether 'key' is somewhere in the chain */
      if (keyisinteger(n) && keyival(n) == key)
        return gval(n);  /* that's it */
      else {
        int nx = gnext(n);
        if (nx == 0) break;
        n += nx;
      }
    }
    return &absentkey;
  }
}


/*