#include "stm32f103xb.h"
#include <stdint.h>

void delay_us(uint16_t us);
void delay_ms(uint16_t ms);

void GPIO_Config(void);
void LCD_Init(void);
void LCD_Send(uint8_t value, uint8_t rs);
void LCD_Print(char *str);
void LCD_Clear(void);
void LCD_Line2(void);

void print_2digits(uint8_t value);
void print_4digits(uint16_t value);

int main(void)
{
    uint8_t dia = 6, mes = 2;
    uint16_t anio = 2026;

    uint8_t horas = 12, minutos = 0, segundos = 0;

    GPIO_Config();
    LCD_Init();

    LCD_Print("Microcontrolador");
    LCD_Line2();
    LCD_Print("Tarea 2.1");

    while(1)
    {
        if((GPIOB->IDR & (1 << 0)) == 0)
        {
            delay_ms(10);
            while((GPIOB->IDR & (1 << 0)) == 0);
            delay_ms(10);
            break;
        }
    }

    while(1)
    {
        LCD_Clear();

        LCD_Print("Fecha: ");
        print_2digits(dia);
        LCD_Send('/', 1);
        print_2digits(mes);
        LCD_Send('/', 1);
        print_4digits(anio);

        LCD_Line2();
        LCD_Print("Hora: ");
        print_2digits(horas);
        LCD_Send(':', 1);
        print_2digits(minutos);
        LCD_Send(':', 1);
        print_2digits(segundos);

        delay_ms(1000);

        segundos++;

        if(segundos >= 60)
        {
            segundos = 0;
            minutos++;
        }

        if(minutos >= 60)
        {
            minutos = 0;
            horas++;
        }

        if(horas >= 24)
        {
            horas = 0;
            dia++;
        }

        if(dia > 31)
        {
            dia = 1;
            mes++;
        }

        if(mes > 12)
        {
            mes = 1;
            anio++;
        }
    }
}

void GPIO_Config(void)
{
    RCC->APB2ENR |= RCC_APB2ENR_IOPAEN;
    RCC->APB2ENR |= RCC_APB2ENR_IOPBEN;
    RCC->APB2ENR |= RCC_APB2ENR_AFIOEN;

    GPIOA->CRL = 0x22222222;

    GPIOA->CRH &= ~(0xFFF);
    GPIOA->CRH |=  (0x222);

    GPIOB->CRL &= ~(0xF << 0);
    GPIOB->CRL |=  (0x8 << 0);
    GPIOB->ODR |=  (1 << 0);
}

void LCD_Init(void)
{
    delay_ms(20);

    LCD_Send(0x38, 0);
    delay_ms(5);

    LCD_Send(0x38, 0);
    delay_us(150);

    LCD_Send(0x38, 0);
    delay_us(150);

    LCD_Send(0x38, 0);
    LCD_Send(0x0C, 0);
    LCD_Send(0x06, 0);
    LCD_Send(0x01, 0);
    delay_ms(2);
}

void LCD_Send(uint8_t value, uint8_t rs)
{
    if(rs)
        GPIOA->BSRR = (1 << 8);
    else
        GPIOA->BRR = (1 << 8);

    GPIOA->BRR = (1 << 9);

    GPIOA->ODR &= ~(0x00FF);
    GPIOA->ODR |= value;

    GPIOA->BSRR = (1 << 10);
    delay_us(2);
    GPIOA->BRR = (1 << 10);
    delay_us(100);
}

void LCD_Print(char *str)
{
    while(*str)
    {
        LCD_Send(*str, 1);
        str++;
    }
}

void LCD_Clear(void)
{
    LCD_Send(0x01, 0);
    delay_ms(2);
}

void LCD_Line2(void)
{
    LCD_Send(0xC0, 0);
}

void print_2digits(uint8_t value)
{
    uint8_t dec = (value / 10) % 10;
    uint8_t uni = value % 10;

    LCD_Send('0' + dec, 1);
    LCD_Send('0' + uni, 1);
}

void print_4digits(uint16_t value)
{
    uint8_t mil = (value / 1000) % 10;
    uint8_t cen = (value / 100) % 10;
    uint8_t dec = (value / 10) % 10;
    uint8_t uni = value % 10;

    LCD_Send('0' + mil, 1);
    LCD_Send('0' + cen, 1);
    LCD_Send('0' + dec, 1);
    LCD_Send('0' + uni, 1);
}

void delay_us(uint16_t us)
{
    volatile uint32_t i;
    while(us--)
    {
        for(i = 0; i < 8; i++);
    }
}

void delay_ms(uint16_t ms)
{
    volatile uint32_t i;
    while(ms--)
    {
        for(i = 0; i < 2000; i++);
    }
}