/* Instruction Press any button except * and #
   button 'C' is to Clear Screen,
   others will be displayed as it is.*/ 
void outport_d(char );
void outport_b(char );
char inport_c();
void wait_until_press();
char check_row_1(char );
char check_row_2(char );
char check_row_3(char );
char check_row_4(char );
void setup() 
{
  outport_d(0x00);
  char z,key=0;
  while(1)
  {
    if(key==0||key==7||key==1||key==12){outport_b(0x3C);}
    else{outport_b(0x3D);}
    
     wait_until_press();
     outport_b(0x00);
    
     dly(); // row 1
     outport_b(0x20);
     z=inport_c();
     key=check_row_1(z);

     if(key==1)
     {
       outport_d(0x18);outport_b(0x3C);delay(500);
     }
     else if(key==2)
     {
       outport_d(0x6C);outport_b(0x3D);
       for(int j=0;j<15;j++){delay();}
     }
     else if(key==3)
     {
       outport_d(0x3C);outport_b(0x3D);
       for(int j=0;j<15;j++){delay();}
     }
     else if(key==10)
     {
       outport_d(0xDC);outport_b(0x3D);
       for(int j=0;j<15;j++){delay();}
     }
     else if(key==100)
     {
       outport_b(0x10);
       z=inport_c();
       key=check_row_2(z);

       if(key==4)
       {
         outport_d(0x98);outport_b(0x3D);
         for(int j=0;j<15;j++){delay();}
       }
       else if(key==5)
       {
         outport_d(0xB4);outport_b(0x3D);
         for(int j=0;j<15;j++){delay();}
       }
       else if(key==6)
       {
         outport_d(0xF4);outport_b(0x3D);
         for(int j=0;j<15;j++){delay();}
       }
       else if(key==11)
       {
        outport_d(0xF0);outport_b(0x3D);
        for(int j=0;j<15;j++){delay();} 
       }
       else if(key==100)
       {
         outport_b(0x08);
         z=inport_c();
         key=check_row_3(z);
         
         if(key==7)
         {
           outport_d(0x1C);outport_b(0x3C);
           for(int j=0;j<15;j++){delay();}
         }
         else if(key==8)
         {
           outport_d(0xFC);outport_b(0x3D);
           for(int j=0;j<15;j++){delay();}
         }
         else if(key==9)
         {
           outport_d(0xBC);outport_b(0x3D);
           for(int j=0;j<15;j++){delay();}
         }
         else if(key==12)
         {
           outport_d(0x00);outport_b(0x3C);
         }
         else if(key==100)
         {
           outport_b(0x04);
           z=inport_c();
           key=check_row_4(z);

           if(key==0)
           {
             outport_d(0xFC);outport_b(0x3C);
           }
           else if(key==13)
           {
             outport_d(0x78);outport_b(0x3D);
             for(int j=0;j<15;j++){delay();}
           }
         }
       }
     }
     delay();

  }
  

}
char inport_c()
{
  char q;
  volatile char *dir_c,*inn_c;
  dir_c=0x27;inn_c=0x26;
  *dir_c=0x00;
  q=*inn_c;
  return q;
}
void wait_until_press()
{
  volatile char *dir_c,*inn_c;
  dir_c=0x27;inn_c=0x26;
  *dir_c=0x00;
  while(*inn_c==0);
}
void outport_d(char q)
{
  volatile char *dir_d,*out_d;
  dir_d=0x2A;out_d=0x2B;*dir_d=0xFC;
  *out_d=q;
}
void outport_b(char q)
{
  volatile char *dir_b,*out_b;
  dir_b=0x24;out_b=0x25;*dir_b=0x3D;
  *out_b=q;
}
char check_row_1(char z)
{
  if(z==0x01)
  {
    return 1;
  }
  else if(z==0x02)
  {
    return 2;
  }
  else if(z==0x04)
  {
    return 3;
  }
  else if(z==0x08)
  {
    return 10;
  }
  else
  {
    return 100;
  }

}
char check_row_2(char z)
{
  if(z==0x01)
  {
    return 4;
  }
  else if(z==0x02)
  {
    return 5;
  }
  else if(z==0x04)
  {
    return 6;
  }
  else if(z==0x08)
  {
    return 11;
  }
  else
  {
    return 100;
  }

}
char check_row_3(char z)
{
  if(z==0x01)
  {
    return 7;
  }
  else if(z==0x02)
  {
    return 8;
  }
  else if(z==0x04)
  {
    return 9;
  }
  else if(z==0x08)
  {
    return 12;
  }
  else
  {
    return 100;
  }

}
char check_row_4(char z)
{
  if(z==0x02)
  {
    return 0;
  }
  else if(z==0x08)
  {
    return 13;
  }
  else
  {
    return 100;
  }
}
void delay()
{
  volatile long i;
  for(i=0;i<20000;i++);
}
void dly()
{
  volatile long i;
  for(i=0;i<300;i++);
}
void loop() {
  // put your main code here, to run repeatedly:

}