extern "C" {
  #include <libopencm3/stm32/rcc.h>
  #include <libopencm3/stm32/gpio.h>
  #include <libopencm3/cm3/nvic.h>
  #include <libopencm3/stm32/usart.h>
}

#define __IO volatile

static inline void usart_enable_idle_interrupt(uint32_t usart)
{
  USART_CR1(usart) |= USART_CR1_IDLEIE;
}

static inline void usart_disable_idle_interrupt(uint32_t usart)
{
  USART_CR1(usart) &= ~USART_CR1_IDLEIE;
}

static inline void usart_clear_idle_flag([[maybe_unused]]uint32_t usart)
{
    __IO uint32_t tmpreg;
    tmpreg = USART2_SR;
    (void) tmpreg;
    tmpreg = USART2_DR;
    (void) tmpreg;

}

//PA2 -> TX2
//PA3 -> RX2

void clock_setup()
{
  //Led
  rcc_periph_clock_enable(RCC_GPIOC);

  //USART
  rcc_periph_clock_enable(RCC_GPIOA);
  rcc_periph_clock_enable(RCC_USART2);

}

int main()
{
  clock_setup();

  //Led
  gpio_mode_setup(GPIOC, GPIO_MODE_OUTPUT, GPIO_PUPD_PULLUP, GPIO13);
  gpio_set(GPIOC, GPIO13);

  // -> GPIO
  //
	/* Setup GPIO pins for USART2 transmit. */
	gpio_mode_setup(GPIOA, GPIO_MODE_AF, GPIO_PUPD_NONE, GPIO2);

	/* Setup GPIO pins for USART2 receive. */
	gpio_mode_setup(GPIOA, GPIO_MODE_AF, GPIO_PUPD_NONE, GPIO3);
	// gpio_set_output_options(GPIOA, GPIO_OTYPE_OD, GPIO_OSPEED_25MHZ, GPIO3);

	/* Setup USART2 TX and RX pin as alternate function. */
	gpio_set_af(GPIOA, GPIO_AF7, GPIO2);
	gpio_set_af(GPIOA, GPIO_AF7, GPIO3);

	/* Setup USART2 parameters. */
	usart_set_baudrate(USART2, 9600);
	usart_set_databits(USART2, 8);
	usart_set_stopbits(USART2, USART_STOPBITS_1);
	usart_set_mode(USART2, USART_MODE_TX_RX);
	usart_set_parity(USART2, USART_PARITY_NONE);
	usart_set_flow_control(USART2, USART_FLOWCONTROL_NONE);

	/* Enable USART2 Receive interrupt. */
	// usart_enable_rx_interrupt(USART2);
  usart_enable_idle_interrupt(USART2);

  /* Enable NVIC irq */
  nvic_enable_irq(NVIC_USART2_IRQ);

	/* Finally enable the USART. */
	usart_enable(USART2);

  while(true)
  {
    __asm("nop");
  }
}

void usart2_isr()
{
  if (((USART_CR1(USART2) & USART_CR1_IDLEIE) != 0) &&
       ((USART_SR(USART2) & USART_FLAG_IDLE) != 0)
     )
  {
    usart_clear_idle_flag(USART2);

    [[maybe_unused]] int x = 10;
  }
}