comms.py 文件源码

def sym2bi(x, m):
    """Convert symbols to bits.

    :param x: symbol array
    :param m: symbol alphabet size (must be a power of 2)
    :returns: bit array

    >>> import arlpy
    >>> arlpy.comms.sym2bi([1, 2, 7], 8)
    array([0, 0, 1, 0, 1, 0, 1, 1, 1])
    """
    n = int(_np.log2(m))
    if 2**n != m:
        raise ValueError('m must be a power of 2')
    x = _np.asarray(x, dtype=_np.int)
    if _np.any(x < 0) or _np.any(x >= m):
        raise ValueError('Invalid data for specified m')
    y = _np.zeros((len(x), n), dtype=_np.int)
    for i in range(n):
        y[:, n-i-1] = (x >> i) & 1
    return _np.ravel(y)