typedef struct
{
  int d4, d5, d6, d7;
} lcd_4bits;

typedef struct
{
  int d0, d1, d2, d3, d4, d5, d6, d7;
} lcd_8bits;

void lcd_attach_4bits(lcd_4bits* lcd)
{
  // Attach 4 bits lcd
}

void lcd_attach_8bits(lcd_8bits* lcd)
{
  // Attack 8 bits lcd
}

void lcd_send_cmd_4bits(lcd_4bits* lcd, int cmd)
{
  // Send 4 bits command
}

void lcd_send_cmd_8bits(lcd_8bits* lcd, int cmd)
{
  // Send 8 bits command
}

int main(void)
{
  lcd_4bits lcd4;
  lcd_8bits lcd8;

  // Setup
  lcd4.d4 = 1;
  lcd8.d0 = 2;
  // Etc

  // Attach
  lcd_attach_4bits(&lcd4);
  lcd_attach_8bits(&lcd8);
  return 0;
}