void init_port(void);
void out_data(char);
void out_ctrl(char);
void delay1(int);
void lcd_ctrl_write(void);
void init_lcd(void);
void write_data(char);
void write_string(char *ptr);

void setup() {
  // put your setup code here, to run once:
  init_port();
  init_lcd();
  write_string("Hello World!");
}

void write_string(char *ptr)
{
  while(*ptr != 0)
  {
    write_data(*ptr);
    ptr++;
  }
}

void init_port()
{
  volatile char* portf_dir = (volatile char*) 0x30;
  volatile char* portk_dir = (volatile char*) 0x107;
  *portf_dir = 0xFF;  // Set PORTF as output
  *portk_dir = 0x03;  // Set PORTK lower 2 bits as output
}

void out_data(char outdata)
{
  volatile char* portf_out = (volatile char*) 0x31;
  *portf_out = outdata;  // Output data to PORTF
}

void out_ctrl(char outctrl)
{
  volatile char* portk_ctrl = (volatile char*) 0x108;
  *portk_ctrl = outctrl;  // Output control signals to PORTK
}

void init_lcd()
{
  out_data(0x38);  // Function set: 8-bit, 2 line, 5x8 dots
  lcd_ctrl_write();
  delay1(2);

  out_data(0x0F);  // Display on, cursor blinking
  lcd_ctrl_write();
  delay1(2);

  out_data(0x01);  // Clear display
  lcd_ctrl_write();
  delay1(2);

  out_data(0x06);  // Entry mode set: increment cursor, no shift
  lcd_ctrl_write();
  delay1(2);
}

void write_data(char wrdata)
{
  out_data(wrdata);  // Send data to PORTF
  out_ctrl(0x02);    // RS = 1, RW = 0 (write data)
  delay1(1);
  out_ctrl(0x03);    // Enable = 1
  delay1(1);
  out_ctrl(0x02);    // Enable = 0
  delay1(1);
}

void lcd_ctrl_write()
{
  out_ctrl(0x01);  // RS = 0, RW = 0 (write instruction)
  delay1(1);
  out_ctrl(0x00);  // Enable = 0
  delay1(1);
}

void delay1(int ms)
{
  // Simple delay loop (not accurate but illustrative)
  for(int i = 0; i < ms * 1000; i++)
  {
    asm volatile ("nop");
  }
}

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

}