void pcint_isr_func(volatile u8t * PINx, u8t & changed_bits, u8t offset){
    u8t registerBit = 0;
    bool callable = false;
    for( ; registerBit < sizeof(changed_bits)*8; ++registerBit){
    if(is_bit_on(changed_bits, registerBit)){
        break;
    }
    }
    u8t pcint_no = registerBit+offset;
    switch (pc_int_isr_vect[pcint_no].edge) {
    case ANY_EDGE:
    callable = true;
    break;
    case RISING:
    if (*PINx &  bitValue(registerBit)) {
        callable = true;
    }
    break;
    case LOW_LEVEL:
    case FALLING:
    if (*PINx & (1<<registerBit) == 0 ) {
        callable = true;
    }
    break;
    default:
    return;

    }
    if(callable){
    if( nullptr !=  pc_int_isr_vect[pcint_no].user_cb){
        pc_int_isr_vect[pcint_no].user_cb(registerBit+offset);
    }
    else if(nullptr != pc_int_isr_vect[pcint_no].context) {
        SystemEventHandler::call_int_callback(pc_int_isr_vect[pcint_no].context, pcint_no);
    }
    }

}

volatile u8t port_b_history = PINB; // start whith pulled-up pins ;
ISR(PCINT0_vect){
    u8t changed_bits = PINB ^ port_b_history;
    port_b_history = PINB;
    pcint_isr_func(&port_b_history, changed_bits, 0);

}