import struct
import binascii


def get_bin(value, padn=0, sep=None):
    """Prints a binary textual representation of a value in """
    return format(value, 'b').zfill(padn)


# Packing a data structure

values = (1, b'ab', 2.7)
s = struct.Struct('I 2s f')
packed_data = s.pack(*values)

print("\n##### Struct Packing Example #####\n\n")
print('Original values      :', values)
print('Packed Type          :', type(packed_data))
# This is most likely going to contain non ascii characters when printed.
# So it's not suitable to copy it over the printed string and then try to
# hexlify
print('Packed print         :', packed_data)
print('Format string        :', s.format)
print('Uses                 :', s.size, 'bytes')
print('Packed Value (hex)   :', binascii.hexlify(packed_data))
# binascii.hexlify(data[, sep[, bytes_per_sep=1]]) can also make more
# human readable values
print('Spaced Value (hex)   :', binascii.hexlify(packed_data, b"_", 4))

# Unpacking a data structure

packed_data = binascii.unhexlify('0100000061620000cdcc2c40')

unpacked_data = s.unpack(packed_data)

print("\n##### Struct Unpacking Example #####\n\n")
print('Unpacked Values:', unpacked_data)

# Endianness in binary data

print("\n##### Endianness Demonstration #####\n\n")
print('Original values:', values)

endianness = [
    ('@', 'native, native'),
    ('=', 'native, standard'),
    ('<', 'little-endian'),
    ('>', 'big-endian'),
    ('!', 'network'),
]

for code, name in endianness:
    s = struct.Struct(code + ' I 2s f')
    packed_data = s.pack(*values)

    print('Format string  :', s.format, 'for', name)
    print('Uses           :', s.size, 'bytes')
    print('Packed Value   :', binascii.hexlify(packed_data))
    print('Unpacked Value :', s.unpack(packed_data), "\n")