bitstruct 2.0.1

This module performs conversions between Python values and C bit field structs represented as Python bytearrays.

About

This module is intended to have a similar interface as the python struct module, but working on bits instead of primitive data types (char, int, …).

Documentation: http://bitstruct.readthedocs.org/en/latest

Installation

pip install bitstruct

Example usage

See the test suite: https://github.com/eerimoq/bitstruct/blob/master/tests/test_bitstruct.py

A basic example of packing/unpacking four integers:

>>> from bitstruct import *
>>> pack('u1u3u4s16', 1, 2, 3, -4)
bytearray(b'\xa3\xff\xfc')
>>> unpack('u1u3u4s16', bytearray(b'\xa3\xff\xfc'))
(1, 2, 3, -4)
>>> calcsize('u1u3u4s16')
24

The unpacked fields can be named by assigning them to variables or by wrapping the result in a named tuple:

>>> from bitstruct import *
>>> from collections import namedtuple
>>> MyName = namedtuple('myname', [ 'a', 'b', 'c', 'd' ])
>>> unpacked = unpack('u1u3u4s16', bytearray(b'\xa3\xff\xfc'))
>>> myname = MyName(*unpacked)
>>> myname
myname(a=1, b=2, c=3, d=-4)
>>> myname.c
3

An example of packing/unpacking a unsinged integer, a signed integer, a float, a boolean and a bytearray:

>>> from bitstruct import *
>>> pack('u5s5f32b1r13', 1, -1, 3.75, True, bytearray(b'\xff\xff'))
bytearray(b'\x0f\xd0\x1c\x00\x00?\xff')
>>> unpack('u5s5f32b1r13', bytearray(b'\x0f\xd0\x1c\x00\x00?\xff'))
(1, -1, 3.75, True, bytearray(b'\xff\xf8'))
>>> calcsize('u5s5f32b1r13')
56

An example of unpacking values from a hexstring and a binary file:

>>> from bitstruct import *
>>> from binascii import *
>>> unpack('s17s13r24', bytearray(unhexlify('0123456789abcdef')))
(582, -3751, bytearray(b'\xe2j\xf3'))
>>> with open("test.bin", "rb") as fin:
...     unpack('s17s13r24', bytearray(fin.read(8)))
...
...
(582, -3751, bytearray(b'\xe2j\xf3'))

Change endianness of the data with byteswap(), and then unpack the values:

>>> from bitstruct import *
>>> packed = pack('u1u3u4s16', 1, 2, 3, 1)
>>> unpack('u1u3u4s16', byteswap('12', packed))
(1, 2, 3, 256)