volatile static unsigned long operator_sign=0,d=0;
volatile static long i=0,y=0;
volatile char buffer[20];
void unsigned_long_to_string(unsigned long num,char *buffer);

#include "suryaa.h"
void setup()
{
  pin_configure();
  init_lcd();
  display_welcome_message();
  display_calculator_features();
  display_instruction_manual();
  display_start_message();
}

void loop()
{
  init2_lcd();
  volatile unsigned long a=0,b=0,c=0,m;
  volatile float x=0.00;
  a=digit_press1();
  for(m=0;m<50000;m++);
  if(i <= 5)
  {
    for(m=0;m<50000;m++);
  b=digit_press2();
  
  if(operator_sign==1)
  {
    c=a+b;
   //  sprintf(buffer, "%lu", c);
   unsigned_long_to_string(c,buffer);
              write_string(buffer);
              clear_buffer();
  }
  else if(operator_sign==5)
  {
    out_data(0x01);
  lcd_control_write();
  out_data(0x80);
  lcd_control_write();
  write_string("out_of_bound..!!");
  out_data(0xc0);
  lcd_control_write();
  write_string("press[*]=> RESET");
  }
  
  else if(operator_sign==2)
  {
    if(a>b)
    {
      c=a-b;
         unsigned_long_to_string(c,buffer);
         write_string(buffer);
         clear_buffer();
    }
    else if(a==b)
    {
     unsigned_long_to_string(c,buffer);
              write_string(buffer);
              clear_buffer();
    }
    else
    {
      c=b-a;
      write_string("-");
      unsigned_long_to_string(c,buffer);
      write_string(buffer);
      clear_buffer();
    }
  }
  else if(operator_sign==3)
  {
    c=a*b;
     unsigned_long_to_string(c,buffer);
              write_string(buffer);
              clear_buffer();
  }
  else if(operator_sign==4)
  {
    x=(float)a/(float)b;
    dtostrf(x, 4, 2, buffer);
    write_string(buffer);
    clear_buffer();
    write_string("(approx)");
  }
  
    volatile long k=0;
    y=0;
    i=0;
  operator_sign=0;
  check_reset();
  for(k=0;k<50000;k++);

  }
else
{
  volatile long k=0;
i=0;
operator_sign=0;
out_data(0x01);
  lcd_control_write();
  out_data(0x80);
  lcd_control_write();
  write_string("out_of_bound..!!");
  out_data(0xc0);
  lcd_control_write();
  write_string("press[*]=> RESET");
  for(k=0;k<50000;k++);
 check_reset();
}
}