"""Interpret sun audio headers."""

MAGIC = '.snd'

class error(Exception):

    pass

def get_long_be(s):

    """Convert a 4-char value to integer."""

    return (ord(s[0])<<24) | (ord(s[1])<<16) | (ord(s[2])<<8) | ord(s[3])

def gethdr(fp):

    """Read a sound header from an open file."""

    if fp.read(4) != MAGIC:

        raise error, 'gethdr: bad magic word'

    hdr_size = get_long_be(fp.read(4))

    data_size = get_long_be(fp.read(4))

    encoding = get_long_be(fp.read(4))

    sample_rate = get_long_be(fp.read(4))

    channels = get_long_be(fp.read(4))

    excess = hdr_size - 24

    if excess < 0:

        raise error, 'gethdr: bad hdr_size'

    if excess > 0:

        info = fp.read(excess)

    else:

        info = ''

    return (data_size, encoding, sample_rate, channels, info)

def printhdr(file):

    """Read and print the sound header of a named file."""

    hdr = gethdr(open(file, 'r'))

    data_size, encoding, sample_rate, channels, info = hdr

    while info[-1:] == '\0':

        info = info[:-1]

    print 'File name:  ', file

    print 'Data size:  ', data_size

    print 'Encoding:   ', encoding

    print 'Sample rate:', sample_rate

    print 'Channels:   ', channels

    print 'Info:       ', repr(info)