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

static void clock_setup(void) {
  // Use external 8 MHz HSE and PLL to 72 MHz
  rcc_clock_setup_pll(&rcc_hse_configs[RCC_CLOCK_HSE8_72MHZ]);
  rcc_periph_clock_enable(RCC_GPIOC);
}

static void gpio_setup(void) {
  // gpio_mode_setup(GPIOC, GPIO_MODE_OUTPUT, GPIO_PUPD_NONE, GPIO13);
  gpio_set_mode(GPIOC, GPIO_MODE_OUTPUT_2_MHZ, GPIO_CNF_OUTPUT_PUSHPULL,
                GPIO13);
}

static void delay(volatile uint32_t count) {
  while (count-- > 0) {
    __asm__("nop");
  }
}

int main(void) {
  clock_setup();
  gpio_setup();

  while (1) {
    gpio_toggle(GPIOC, GPIO13); // On Blue Pill: LED is on PC13
    delay(10000000);            // Crude delay loop
  }

  return 0;
}