#include "DNA_math.h"
void delay1()
{
  volatile long i;
  for(i=0;i<10000;i++);
}
void delay2()
{
  volatile long i;
  for(i=0;i<2000;i++);
}
void delay3()
{
  volatile long i;
  for(i=0;i<20000;i++);
}
void port_initializations()
{
  volatile char *portF_dir;
  volatile char *portK_dir;
  volatile char *portA_dir;

  portF_dir=0x30;
  portK_dir=0x107;
  portA_dir=0x21;

  *portA_dir=0x0F;
  *portF_dir=0xFF;
  *portK_dir=0xFF;  
}
void LCD_outdata(char data1)
{
    volatile char *portF_data;
    portF_data=0x31;
    *portF_data=data1;
}
void ENABLE_and_RS_pin(char data2)
{
    volatile char *portK_data;
    portK_data=0x108;
    *portK_data=data2;
}
void Keypad_Row(char data3)
{
    volatile char *portA_data;
    portA_data=0x22;
    *portA_data=data3 & 0x0F;
}
char Keypad_column()
{
  char data4;
  volatile char *portA_input;
  portA_input=0x20;
  data4=(*portA_input & 0xF0)>>4;
  data4=(~(data4)) & 0x0F;
  return data4;
}
char get_key()
{
  int row,col;
  char key_value,column;
 for(row=0;row<4;row++)
  {
     Keypad_Row(~(1<<row));
  for(col=0;col<4;col++)
  {
    column=Keypad_column();
       if(column!=0x00)
       { 
            delay1();
         for(col=0;col<4;col++)
            { 
                 if(column==(1<<col))
                 {
                 key_value=row*4+col+1;
                 delay1();
                 return(key_value);
                 }
          }
       }
   }
  }
  return(0);
}
void Enable_pulse()
{
  ENABLE_and_RS_pin(0x01);
  delay2();
  ENABLE_and_RS_pin(0x00);
  delay2();
}
void LCD_initialization()
{
  LCD_outdata(0x38);
  Enable_pulse();
  LCD_outdata(0x0E);
  Enable_pulse();
}
void write_data_LCD(char data5)
{
  LCD_outdata(data5);
  ENABLE_and_RS_pin(0x02);
  delay2();
  ENABLE_and_RS_pin(0x03);
  delay2();
  ENABLE_and_RS_pin(0x02);
  delay2();
  ENABLE_and_RS_pin(0x00);
}
void clear_display()
{
  LCD_outdata(0x01);
  Enable_pulse();
}
void Return_home()
{
  LCD_outdata(0x02);
  Enable_pulse();
}
void shift_or_cursor()
{
  LCD_outdata(0x10);
  Enable_pulse();
}
void Set_DDRAM_Address(char data6)
{
  LCD_outdata(data6);
  Enable_pulse();
}
void Display_string(char *pos)
{
  while(*pos!=0)
  {
    write_data_LCD(*pos);
    *pos++;
  }
}
void clear_inputs(char input[])
{
  int i;
  for(i=0;i<5;i++)
  {
    input[i]='\0';
  }
}
void clear_outputs(char output1[])
{
  int i;
  for(i=0;i<17;i++)
  {
    output1[i]='\0';
  }
}
void setup() {
  // put your setup code here, to run once:
  Serial.begin(9600);
  char key,input1[8],input2[8],output[17];
  int i,flag=0,j=0,out=0,operation,check=0;
  port_initializations();
  LCD_initialization();
  char key_binding[16]={'1','2','3','+','4','5','6','-','7','8','9','*','<','0','=','/'};
  while(1)
  {
    key=get_key();
    while(key==0 && out==0)
    {
      key=get_key();
      for(i=1;i<=16;i++)
      {
        if(i==key)
        {
           if(key==15)
          {
            write_data_LCD(key_binding[i-1]);
            out=1;
           // Serial.println("the value of out is ");
           // Serial.println(out);
          }
          if(key==13)
          {
            shift_or_cursor();
            write_data_LCD(' ');
            if(check==1)
            {
              operation=0;
            }
            else{
              j=j-1;
            }
             shift_or_cursor();
          }
          if(((key!=4)&&(key!=8)&&(key!=12)&&(key!=15)&&(key!=16)&&(key!=13))&&flag==0)
          {
            write_data_LCD(key_binding[i-1]);
            input1[j]=key_binding[i-1];
           // Serial.println(j);
           // Serial.println(" ");
            j=j+1;
            input1[j]=0;
          }
          if(((key!=4)&&(key!=8)&&(key!=12)&&(key!=15)&&(key!=16)&&(key!=13))&&flag==1)
          {
             write_data_LCD(key_binding[i-1]);
             check=0;
             input2[j]=key_binding[i-1];
             //Serial.println(input2[j]);
            // Serial.println(" ");
             j=j+1;
             input2[j]=0;
          }
          if(key==4||key==8||key==12||key==16)
          {
            write_data_LCD(key_binding[i-1]); 
            operation=key;
            check=1;
            flag=1;
            j=0;
          }
          
         }
      }
      delay3();
    }
   // Serial.println("out of the while");
    if(out==1)
    {
      // Serial.println("the value of operation  is ");
      // Serial.println(operation,DEC);
      if (operation==4)
      {
     // Serial.println("the value of inputl is");
     // Serial.println(input1);
     // Serial.println("the value of input2 is");
    //  Serial.println(input2);
      Serial.println("Addition");
      addition(input1,input2,output);
    //  Serial.println("the value of Addition output is");
    //  Serial.println(output);
      Return_home();
      Set_DDRAM_Address(0xC0);
       Display_string(output);
      }
      if (operation==8)
      {
        Serial.println("Subtraction");
        subtraction(input1,input2,output);
        Return_home();
        Set_DDRAM_Address(0xC0);
        Display_string(output);
      }
      if (operation==12)
      {
        Serial.println("Multiplication");
        multiplication(input1,input2,output);
        Return_home();
        Set_DDRAM_Address(0xC0);
        Display_string(output);
      }
      if (operation==16)
      {
        Serial.println("Division");
        division_quotient(input1,input2,output);
        Return_home();
        Set_DDRAM_Address(0xC0);
        Display_string(output);
      }
      operation=0;
    }
    if(key==13&&out==1)
    {
             Return_home();
            //Set_DDRAM_Address(0x80);
            clear_display();
          //  Serial.println("Clear");
            clear_inputs(input1);
            clear_inputs(input2);
            clear_outputs(output);
            out=0;
            j=0;
            flag=0;
    }
  }
}

void loop() {
  // put your main code here, to run repeatedly:

}