#include "stm32f0xx.h"

#define PINOUT_LED_1 3
#define PINOUT_LED_2 5
#define PINOUT_LED_3 4
#define PINOUT_LED_4 6

const unsigned short leds[] = {PINOUT_LED_1, PINOUT_LED_2, PINOUT_LED_3, PINOUT_LED_4};

/*
 * This function configures the I/O-ports that are used by the I/O-shield. It
 * uses register RCC_AHBENR to enable the clocks for the ports that are used,
 * register  GPIOx_MODER to configure pins as input, analog or output and
 * GPIOx_PUPDR to configure pull-up and pull-down resistors.
 */
void shieldConfig() {
	// enable clock for I/O port D
	RCC->AHBENR |= RCC_AHBENR_GPIOBEN;

	GPIOB->MODER &= ~((0b11 << (PINOUT_LED_1 * 2)) |\
	                  (0b11 << (PINOUT_LED_2 * 2)) |\
	                  (0b11 << (PINOUT_LED_3 * 2)) |\
	                  (0b11 << (PINOUT_LED_4 * 2)));

	GPIOB->MODER |= (0b01 << (PINOUT_LED_1 * 2)) |\
	                (0b01 << (PINOUT_LED_2 * 2)) |\
	                (0b01 << (PINOUT_LED_3 * 2)) |\
	                (0b01 << (PINOUT_LED_4 * 2));
}

/*
 * This function drives led <num> of the I/O-shield. <num> should be the number
 * of the LED to drive (0, 1, 2 or 3) and <on> should be an integer with value
 * 0 or 1 which indicates if the LED should be turned on (1) or off (0).
 */
void ledWrite(int num, int on) {
	GPIOB->ODR &= ~(1 << leds[num]);
	GPIOB->ODR |= (on << leds[num]);
}

/*
 * This function returns the status of the pushbutton of the I/O-shield.
 * Return value 1 indicates that the button is currently pressed and return
 * value 0 indicates that the button is currently not pressed.
 */
int buttonRead() {
	return 0;
}

void delay()
{
	int i;
	for (i = 0; i < 50000; i++)
	{
		asm("nop");
	}
}
int main()
{
	shieldConfig();

	// RCC->AHBENR |= RCC_AHBENR_GPIOAEN;
	// GPIOA->MODER &= ~(1 << (PINOUT_LED_1 * 2 + 1));
	// GPIOA->MODER |=  (1 << (PINOUT_LED_1 * 2));

	// GPIOA_MODER &= ~(0 << (PINOUT_LED_1 * 2 + 1));

	while (1)
	{
		for(int i = 0; i < 2 * 4; i++) {
			ledWrite(i % 4, i >= 4);

			delay();
		}
	}
}