def add_dummy_data(bitmap, width, height):
    """
    Adds dummy data to a bitmap to ensure the width is divisible by 4. 
    This is required because the SSD1322 OLED driver maintains a single column 
    address for four pixels.
    
    bitmap (list): A list of integers (pixel values)
    width (int): The width of the bitmap
    height (int): The height of the bitmap
    
    Returns (tuple): A tuple which contains modified image data.
                     |
                     |--> bitmap_data (tuple)
                     |    |--> bitmap pixel array (list)
                     |    |--> bitmap width  (int)
                     |    \--> bitmap height (int)
                     |
                     \--> dummy_to_add (int): Columns of dummy data added
    """
    output = []
    bitmap_data = tuple()
    # Maximum dummy data should be 3 
    dummy_to_add = (4 - (width % 4)) % 4
    
    new_width = width + dummy_to_add
    
    if dummy_to_add > 0:
        index = 0
        for i in range(height):
            for j in range(new_width):
                # Add dummy data beyond original width
                if j > (width - 1):
                    output.append(0)
                else:
                    output.append(bitmap[index])
                    index += 1
        bitmap_data = (output, new_width, height)
    else:
        bitmap_data = (bitmap, width, height)
    
    return (bitmap_data, dummy_to_add)