def calc_bits(offset, size):
    """
    Generates the string of where the bits of that property in a register live 

    Parameters
    ----------
    offset : int,  
    size : int, 

    Returns 
    ----------
    ret_str : str, the string
    """

    # Generate the register bits
    if size == 1:
        ret_str = "[" + str(offset) + "]"
    else:
        top_bit = offset + size - 1
        ret_str = "[" + str(top_bit) + ":" + str(offset) + "]"

    return ret_str