BinField 0.7.1

binfield

Python binfield implementation for binary data manipulation.

Why? Python supports binary data manipulation via binary operations out of the box and it’s fast, but it’s hard to read and painful during prototyping, especially for complex (nested) structures.

This library is desined to fix this issue: it allows to operate with binary data like dict with constant indexes: you just need to define structure class and create an instance with start data. Now you can use indexes for reading and writing data

Pros:

• Free software: Apache license

• Open Source: https://github.com/penguinolog/binfield

• Self-documented code: docstrings with types in comments

• Tested: see bages on top

• Support multiple Python versions:

Python 2.7
Python 3.4
Python 3.5
Python 3.6
PyPy
PyPy3
Jyton 2.7

Usage

Not mapped objects could be created simply from BinField class:

bf = BinField(42)

Data with fixed size should be created as new class (type): Example on real data (ZigBee frame control field):

# Describe
class ZBFrameControl(binfield.BinField):
    _size_ = 16  # Optional, used as source for mask, if mask is not defined
    _mask_ = 0xFF7F  # Optional, used as source for size, if size is not defined
    FrameType = [0, 3]  # Enum
    Security = 3
    FramePending = 4
    AckRequest = 5
    PAN_ID_Compression = 6
    SequrityNumberSuppress = 8
    InformationPresent = 9
    DstAddrMode = [10, 12]
    FrameVersion =  [12, 14]
    SrcAddrMode = [14, 16]

# Construct from frame
# (limitation: endianless convertation is not supported, make it by another tools)
frame = frame = ZBFrameControl(0x0803)  # Beacon request

>>> print(frame)
<2051 == 0x0803 == (0b0000100000000011 & 0b1111111111111111)
  FrameType             = <3 == 0x03 == (0b011 & 0b111)>
  Security               = <0 == 0x00 == (0b0 & 0b1)>
  FramePending           = <0 == 0x00 == (0b0 & 0b1)>
  AckRequest             = <0 == 0x00 == (0b0 & 0b1)>
  PAN_ID_Compression     = <0 == 0x00 == (0b0 & 0b1)>
  SequrityNumberSuppress = <0 == 0x00 == (0b0 & 0b1)>
  InformationPresent     = <0 == 0x00 == (0b0 & 0b1)>
  DstAddrMode            = <2 == 0x02 == (0b10 & 0b11)>
  FrameVersion           = <0 == 0x00 == (0b00 & 0b11)>
  SrcAddrMode            = <0 == 0x00 == (0b00 & 0b11)>

>>> repr(frame)
'ZBFrameControl(x=0x0803, base=16)'

>>> print(frame.FrameType)
<3 == 0x03 == (0b011 & 0b111)>  # Get nested structure: current is flat, so we have single value

# We can use slice to get bits from value: result type is always subclass of BinField
>>> repr(frame.FrameType[: 2])
'<FrameType_slice_0_2(x=0x03, base=16) at 0x7FD0ACA57408>'

>>> frame.FrameType == 3  # Transparent comparsion with integers
True

>>> int(frame.FrameType)  # Painless conversion to int
3

>>> bool(frame.AckRequest)  # And bool
False

>>> print(frame[1: 5])  # Ignore indexes and just get few bits using slice
<1 == 0x01 == (0b0001 & 0b1111)>

>>> print(ZBFrameControl.AckRequest)  # Request indexes from created data type
5

>>> print(ZBFrameControl.DstAddrMode)  # Multiple bits too
slice(10, 12, None)

# Modification of nested data (if no type conversion was used) changes original object:
>>> frame.AckRequest = 1
>>> print(frame)
<2083 == 0x0823 == (0b0000100000100011 & 0b1111111101111111)
  FrameType              = <3 == 0x03 == (0b011 & 0b111)>
  Security               = <0 == 0x00 == (0b0 & 0b1)>
  FramePending           = <0 == 0x00 == (0b0 & 0b1)>
  AckRequest             = <1 == 0x01 == (0b1 & 0b1)>
  PAN_ID_Compression     = <0 == 0x00 == (0b0 & 0b1)>
  SequrityNumberSuppress = <0 == 0x00 == (0b0 & 0b1)>
  InformationPresent     = <0 == 0x00 == (0b0 & 0b1)>
  DstAddrMode            = <2 == 0x02 == (0b10 & 0b11)>
  FrameVersion           = <0 == 0x00 == (0b00 & 0b11)>
  SrcAddrMode            = <0 == 0x00 == (0b00 & 0b11)>
>

# But remember, that nested blocks has it's own classes
>>> repr(frame.DstAddrMode)
'<DstAddrMode(x=0x02, base=16) at 0x7FD0AD139548>'

>>> fr2 = ZBFrameControl(0xFFFF)
>>> repr(fr2)
'ZBFrameControl(x=0xFF7F, base=16)'  # Mask if applied, if defined

# Fields could be set only from integers
>>> frame.SrcAddrMode = fr2.SrcAddrMode
Traceback (most recent call last):
...
TypeError: BinField value could be set only as int

>>> repr(frame['FramePending'])  # __getitem__ and __setitem__ is supported
'<FramePending(x=0x00, base=16) at 0x7FD0ACAD3188>'

Nested structures is supported, if required. Definition example (not aligned with any real data):

class NestedMappedBinField(BinField):
    test_index = 0
    nested_block = {
        '_index_': (1, 6),
        'single_bit': 0,
        'multiple': (1, 3)
    }

Note: negative indexes is not supported by design!

Testing

The main test mechanism for the package binfield is using tox. Test environments available:

pep8
py27
py34
py35
py36
pypy
pypy3
jyton
pylint

CI systems

For code checking several CI systems is used in parallel:

1. Travis CI: is used for checking: PEP8, pylint, bandit, installation possibility and unit tests. Also it’s publishes coverage on coveralls.

2. coveralls: is used for coverage display.

CD system

Travis CI: is used for package delivery on PyPI.