#define RCC_AHBENR    (*(unsigned int *)(0x40021000 + 0x14))
#define GPIOB_MODER (*(unsigned int *)(0x48000400 + 0x00))
#define GPIOB_ODR       (*(unsigned int *)(0x48000400 + 0x14))
#define RCC_APB1ENR (*(unsigned int *)(0x40021000 + 0x1C))
#define PWR_CR       (*(unsigned int *)(0x40007000 + 0x00))
#define RCC_BDCR     (*(unsigned int *)(0x40021000 + 0x20))
#define RTC_WPR      (*(unsigned int *)(0x40002800 + 0x24))
#define RTC_ISR      (*(unsigned int *)(0x40002800 + 0x0C))
#define RTC_DR       (*(unsigned int *)(0x40002800 + 0x04))
#define RTC_TR       (*(unsigned int *)(0x40002800 + 0x00))

#define GPIOA_PUPDR  (*(unsigned int *)(0x48000000 + 0x0C))
#define GPIOA_IDR         (*(unsigned int *)(0x48000000 + 0x10))
#define GPIOA_ODR       (*(unsigned int *)(0x48000000 + 0x14))
#define GPIOA_MODER (*(unsigned int *)(0x48000000 + 0x00))

int test = 0;
int token = 0;
int counter = 0;
int i;

void clockSetup() {
	RCC_APB1ENR = (1 << 28);
	PWR_CR = (1 << 8);
	RCC_BDCR = 0x8101;
	RTC_WPR = 0xCA;
	RTC_WPR = 0x53;
	RTC_ISR = (1 << 7);
	while ((RTC_ISR & 0x40) == 0) {
		asm("nop");
	}
	RTC_DR = 0x0;
	RTC_TR = 0x0;
	RTC_ISR &= (0 << 7);
	RTC_WPR = 0xFE;
	RTC_WPR = 0x64;
	PWR_CR &= (0 << 8);
}

void boardSetup() {
	RCC_AHBENR |= (1 << 17);
	GPIOA_PUPDR |= 0x4;
	GPIOA_MODER |= 0x400;
	GPIOA_MODER |= 0x4000;
}

void clock(int pulse) {
	for (int k = 0; k < pulse; k++) {
		GPIOA_ODR |= 0x20;
		GPIOA_ODR &= ~0x20;
	}
}

void begin() {
	GPIOA_ODR |= 0x00A0;
}

void start() {
	GPIOA_ODR &= ~0x80;
	GPIOA_ODR &= ~0x20;
}

void stop() {
	GPIOA_ODR |= 0x20;
	GPIOA_ODR |= 0x80;
}

void acknowledge() {
	clock(1);
}

void zero() {
	GPIOA_ODR |= 0x80;
	clock(6);
	GPIOA_ODR &= ~0x80;
	clock(1);
	GPIOA_ODR |= 0x80;
	clock(1);
	GPIOA_ODR &= ~0x80;
	acknowledge();
}

void one() {
	clock(1);
	GPIOA_ODR |= 0x80;
	clock(2);
	GPIOA_ODR &= ~0x80;
	clock(4);
	GPIOA_ODR |= 0x80;
	clock(1);
	GPIOA_ODR &= ~0x80;
	acknowledge();
}

void two() {
	GPIOA_ODR |= 0x80;
	clock(2);
	GPIOA_ODR &= ~0x80;
	clock(1);
	GPIOA_ODR |= 0x80;
	clock(2);
	GPIOA_ODR &= ~0x80;
	clock(1);
	GPIOA_ODR |= 0x80;
	clock(2);
	GPIOA_ODR &= ~0x80;
	acknowledge();
}

void three() {
	GPIOA_ODR |= 0x80;
	clock(4);
	GPIOA_ODR &= ~0x80;
	clock(2);
	GPIOA_ODR |= 0x80;
	clock(2);
	GPIOA_ODR &= ~0x80;
	acknowledge();
}

void four() {
	clock(1);
	GPIOA_ODR |= 0x80;
	clock(2);
	GPIOA_ODR &= ~0x80;
	clock(2);
	GPIOA_ODR |= 0x80;
	clock(3);
	GPIOA_ODR &= ~0x80;
	acknowledge();

}

void five() {
	GPIOA_ODR |= 0x80;
	clock(1);
	GPIOA_ODR &= ~0x80;
	clock(1);
	GPIOA_ODR |= 0x80;
	clock(2);
	GPIOA_ODR &= ~0x80;
	clock(1);
	GPIOA_ODR |= 0x80;
	clock(3);
	GPIOA_ODR &= ~0x80;
	acknowledge();
}

void six() {
	GPIOA_ODR |= 0x80;
	clock(1);
	GPIOA_ODR &= ~0x80;
	clock(1);
	GPIOA_ODR |= 0x80;
	clock(6);
	GPIOA_ODR &= ~0x80;
	acknowledge();
}

void seven() {
	GPIOA_ODR |= 0x80;
	clock(3);
	GPIOA_ODR &= ~0x80;
	clock(4);
	GPIOA_ODR |= 0x80;
	clock(1);
	GPIOA_ODR &= ~0x80;
	acknowledge();
}

void eight() {
	GPIOA_ODR |= 0x80;
	clock(8);
	GPIOA_ODR &= ~0x80;
	acknowledge();
}

void nine() {
	GPIOA_ODR |= 0x80;
	clock(4);
	GPIOA_ODR &= ~0x80;
	clock(1);
	GPIOA_ODR |= 0x80;
	clock(3);
	GPIOA_ODR &= ~0x80;
	acknowledge();

}
void dataCommand() {
	start();
	clock(6);
	GPIOA_ODR |= 0x80;
	clock(1);
	GPIOA_ODR &= ~0x80;
	clock(1);
	acknowledge();
	stop();
}

void displayControllCommand() {
	start();
	clock(2);
	GPIOA_ODR |= 0x0080;
	clock(2);
	GPIOA_ODR &= ~0x0080;
	clock(3);
	GPIOA_ODR |= 0x0080;
	clock(1);
	GPIOA_ODR &= ~0x0080;
	acknowledge();
	stop();
}

void addressCommand() {
	start();
	clock(6);
	GPIOA_ODR |= 0x80;
	clock(2);
	GPIOA_ODR &= ~0x0080;
	acknowledge();
}
void display(int sec) {
	addressCommand();
	switch (sec) {
	case 0:
		zero();
		break;
	case 1:
		one();
		break;
	case 2:
		two();
		break;
	case 3:
		three();
		break;
	case 4:
		four();
		break;
	case 5:
		five();
		break;
	case 6:
		six();
		break;
	case 7:
		seven();
		break;
	case 8:
		eight();
		break;
	case 9:
		nine();
		break;
	}

	stop();
}

int timerDelay(int sec) {
	if ((RTC_TR & 0x1) == 0) {
		if (test == 0) {
			sec++;
			test++;
		}

	}
	if ((RTC_TR & 0x1) == 1) {
		if (test == 1) {
			sec++;
			test--;
		}

	}
	return sec;
}

void reset(int sec) {
	sec = 0;
	display(sec);
}

int main() {
	int sec = 0;
	boardSetup();
	begin();
	dataCommand();
	displayControllCommand();
	clockSetup();
	reset(sec);
	token = ~token;
	while (1) {
		display(sec % 10);
		display(sec / 10 % 6);
		display(sec / 60 % 10);
		display(sec / 600 % 10);
		sec = timerDelay(sec);

	}
}