#include <libopencm3/stm32/rcc.h>
#include <libopencm3/stm32/gpio.h>
#include <libopencm3/stm32/usart.h>

#include <libopencm3/cm3/systick.h>

int main(void) {
	rcc_periph_clock_enable(RCC_GPIOA);
	rcc_periph_clock_enable(RCC_GPIOB);

	rcc_periph_clock_enable(RCC_USART2);

  // setup PA5-7 and PB1 for the stepper motor gates
  gpio_clear(GPIOA, GPIO5|GPIO6|GPIO7);
  gpio_clear(GPIOB, GPIO1);
  gpio_mode_setup(GPIOA, GPIO_MODE_OUTPUT, GPIO_PUPD_NONE, GPIO5);
  gpio_mode_setup(GPIOA, GPIO_MODE_OUTPUT, GPIO_PUPD_NONE, GPIO6);
  gpio_mode_setup(GPIOA, GPIO_MODE_OUTPUT, GPIO_PUPD_NONE, GPIO7);
  gpio_mode_setup(GPIOB, GPIO_MODE_OUTPUT, GPIO_PUPD_NONE, GPIO1);

  // setup PA2/3 for USART2_RX and USART2_TX
  gpio_mode_setup(GPIOA, GPIO_MODE_AF, GPIO_PUPD_NONE, GPIO2|GPIO3);
  gpio_set_af(GPIOA, GPIO_AF4, GPIO2|GPIO3);

  // setup USART2 stuff
  usart_set_baudrate(USART2, 115200);
	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);
  usart_enable(USART2);

#if 0
  // if I need more speed than the internal 2 MHz
  // setup PA0 as a clock input
  rcc_bypass_enable(RCC_HSE);
  rcc_osc_on(RCC_HSE);

  rcc_wait_for_osc_ready(RCC_HSE);
  rcc_set_sysclk_source(RCC_HSE);
#endif

  // setup systick interrupt
  systick_interrupt_disable();
  systick_counter_disable();

  systick_set_clocksource(STK_CSR_CLKSOURCE_AHB);
  systick_set_reload(rcc_ahb_frequency/100000-1);
  systick_clear();

  systick_interrupt_enable();
  systick_counter_enable();

  while (1) {
    if ((USART_ISR(USART2) & USART_ISR_RXNE) != 0) {
      // TODO process byte
      uint8_t rx = usart_recv(USART2);
      usart_send_blocking(USART2, rx);
    }
  }
}

void SysTick_Handler(void);
void SysTick_Handler(void) {
}