#include <string.h>
#include "lcd.h"
#include "adc.h"
volatile unsigned char int_flag = 0;
unsigned short reverse_num(unsigned short num){
  unsigned short res = 0;
  while(num){
    res = (res * 10) + (num % 10);
    num = num / 10; 
  }
  return res;
}

void my_strrev(unsigned char* str){
    //reverse string
    int start = 0, end = strlen(str) - 1;
    unsigned char temp;
    while(start < end)
    {
        temp = str[start];
        str[start] = str[end];   
        str[end] = temp;
        start++;
        end--;
    }
}    

void my_itoa(unsigned short res, unsigned char* str){
    if (res == 0)
    {
        str[0] = '0';
        str[1] ='\0'; 
        return;
    }
    int i = 0;
    //reverse num
    //unsigned short rev_num = reverse_num(res);
    //Serial.println(rev_num);
    while(res){
      str[i++] = (res % 10) + '0';
      res /= 10;
    }
    str[i] = '\0';
    my_strrev(str);
}

unsigned short fetch_fractional_digits(float fractional_part){
  unsigned short res = 0, digit, nonZeroDigit = 0;
  for(int i = 0; i < 3; i++)
  {
    fractional_part *= 10;
    digit = (unsigned short)fractional_part;
    res = (res * 10) + digit;
    fractional_part = fractional_part - digit;
  }
  //Serial.println(res);
  return res;
}

void init_port() {
  // portk and f as output port
  volatile unsigned char *ddr_portf = 0x30, *ddr_portk = 0x107; 
  *ddr_portf = 0xFF;
  *ddr_portk |= 0x03;
}

void setup() {
  init_port();
  init_lcd();
  adc_init();
  start_adc_conversion();
  Serial.begin(9600);
}

void loop() {
    if(int_flag){
      volatile unsigned short *ADC_DATA_REG = 0x78;
      volatile unsigned short res = *ADC_DATA_REG;
      float result = res * (5.0/1023), fraction_part = 0;

      unsigned char str_res[5] = {0};
      int nonZerodigitIndex = -1;
      //print integer part
      my_itoa((unsigned short)result, str_res);
      set_cursor(LINE1(0));
      write_string(str_res);
      fraction_part = result - (unsigned short)result;
      Serial.println(result, 4);
      res = fetch_fractional_digits(fraction_part);
      //the below is done to accomodate leading 0s in fractional part
      sprintf(str_res, "%03hu", res);
      write_string(".");
      write_string(str_res);
      delay(180);
      outdata(CLEAR_DISPLAY, INST_MODE);
      delayMicroseconds(100);
      int_flag = 0;
      //start conversion again
      start_adc_conversion();
    } 
}


ISR(ADC_vect){
  int_flag = 1;
}