#include "stm32f103xb.h"
#include <stdint.h>
#include "stm32f103_hal.h"

// Arreglo de retardos
uint16_t delay_levels[4] = {8332, 6249, 4166, 2083}; 
// Inicia en el indice 3 (retardo mas corto)
volatile uint8_t current_level = 3; 

void delay_us(uint16_t us)
{
  for (volatile unsigned int cycles = 0; cycles < us; cycles++);
}

void delay_ms(uint16_t ms)
{
  for (volatile uint16_t i = 0; i < ms; i++) {
    delay_us(1000);
  }
}

int main(void)
{
  rcc_clock_enable(RCC_GPIOA);
  rcc_clock_enable(RCC_TIM3);
  rcc_clock_enable(RCC_EXTI);

  gpio_set_output(GPIOA, GPIO_PIN_1, GPIO_OUTPUT_PP, GPIO_SPEED_2MHZ);
  
  gpio_set_input(GPIOA, GPIO_PIN_2, GPIO_INPUT_PU);
  gpio_set_input(GPIOA, GPIO_PIN_3, GPIO_INPUT_PU);

  timer_init(TIM3, TIMER_MODE_UP, delay_levels[current_level], 8); 
  timer_set_interrupt(TIM3, TIMER_IRQ_UPDATE, IRQ_ENABLE);
  nvic_enable_irq(TIM3_IRQn);

  exti_set_interrupt(PA0, EXTI_IRQ_RISING);
  nvic_enable_irq(EXTI0_IRQn);

  nvic_enable();

  uint8_t btn_up_last = 1;
  uint8_t btn_down_last = 1;

  while (1)
  {
    uint8_t btn_up_now = gpio_read_pin(GPIOA, GPIO_PIN_2);
    uint8_t btn_down_now = gpio_read_pin(GPIOA, GPIO_PIN_3);

    if (btn_up_last == 1 && btn_up_now == 0)
    {
      if (current_level < 3) 
      {
        current_level++;
      }
      delay_ms(50); 
    }
    
    if (btn_down_last == 1 && btn_down_now == 0)
    {
      if (current_level > 0) 
      {
        current_level--;
      }
      delay_ms(50);
    }

    btn_up_last = btn_up_now;
    btn_down_last = btn_down_now;
  }
}

void EXTI0_IRQHandler(void)
{
  EXTI->PR = 1; 
  
  TIM3->CNT = 0; 
  TIM3->ARR = delay_levels[current_level]; 
  timer_start(TIM3, TIMER_ONESHOT);
}

void TIM3_IRQHandler(void)
{
  TIM3->SR &= ~1; 
  
  gpio_bitwise_set(GPIOA, 2);  
  delay_us(100);    
  gpio_bitwise_clear(GPIOA, 2); 
}