#include <stm32c0xx.h>

#define LED_PIN0 0
#define LED_PIN1 1
#define LED_PIN2 2

#define BUTTON_PIN0 5
#define BUTTON_PIN1 6
#define BUTTON_PIN2 7

void delay(volatile uint32_t time)
{
  while(time --)
  {
    __asm__("nop");
  }
}

void init_pin_output(uint32_t pin)
{
  GPIOA->MODER = GPIOA->MODER & ~(3 << (pin * 2));
  GPIOA->MODER = GPIOA->MODER | (1 << (pin * 2));
}

void init_pin_input(uint32_t pin)
{
  GPIOA->MODER = GPIOA->MODER & ~(3 << (pin * 2));
}


int main (void)
{
RCC->IOPENR = RCC->IOPENR | RCC_IOPENR_GPIOAEN;

init_pin_output(LED_PIN0);
init_pin_output(LED_PIN1);
init_pin_output(LED_PIN2);

init_pin_input(BUTTON_PIN0);
init_pin_input(BUTTON_PIN1);
init_pin_input(BUTTON_PIN2);

while (1)
{
  if (GPIOA-> IDR & (1 << BUTTON_PIN0))
    GPIOA->ODR = GPIOA->ODR | (1 << LED_PIN0);
  else
    GPIOA->ODR = GPIOA->ODR & ~(1 << LED_PIN0);
  delay(10000);
}
  return 0;
}