#include "stm32f4xx.h"

#define LED1_PIN 10
#define LED2_PIN 11
#define LED3_PIN 12
#define LED4_PIN 13
#define LED_COMMON 1 // Anode: 1, catode: 0


__attribute__((optimize("O0")))
void delay(volatile int cnt) {
    while(cnt--);
}

int main(void) {
    RCC->AHB1ENR |= RCC_AHB1ENR_GPIOCEN;
    GPIOC->MODER |= (1U << (LED1_PIN * 2));
    GPIOC->MODER |= (1U << (LED2_PIN * 2));
    GPIOC->MODER |= (1U << (LED3_PIN * 2));
    GPIOC->MODER |= (1U << (LED4_PIN * 2));

    GPIOC->ODR |= (1U << LED4_PIN);
    while (1) {
        GPIOC->ODR ^= (1U << LED4_PIN) | (1U << LED1_PIN);
        delay(500000);
        GPIOC->ODR ^= (1U << LED1_PIN) | (1U << LED2_PIN);
        delay(500000);
        GPIOC->ODR ^= (1U << LED2_PIN) | (1U << LED3_PIN);
        delay(500000);
        GPIOC->ODR ^= (1U << LED3_PIN) | (1U << LED4_PIN);
        delay(500000);
    }
}