Rescale taps in that way that their sum equals 1

def rescale_taps(taps):
    """
    Rescale taps in that way that their sum equals 1
    """
    taps = np.array(taps)
    cs = sum(taps)
    # fixme: not sure here, abs seems right as it avoids overflows in core,
    # then again it reduces the fir gain
    # cs = sum(abs(taps))
    for (i, x) in enumerate(taps):
        taps[i] = x / cs

    return taps.tolist()