/*
    x+w-1 <= 239
    y+h-1 <= 319
*/
void lcd_window(uint16_t x, uint16_t y, uint16_t w, uint16_t h)
{
    LCD_WriteReg(0x44, ((x+w-1) << 8) | x);
    LCD_WriteReg(0x45, y);
    LCD_WriteReg(0x46, y+h-1);
}