binmap 1.2.0

Description:

binmap 1.2.0

Dataclass for go to and from binary data
It follows dataclass pattern with typehinting as the binary format.
Temperature with one unsigned byte:
>>> class Temperature(BinmapDataclass):
... temp: unsignedchar = 0
...
>>> t = Temperature()
>>> t.temp = 22
>>> print(bytes(t))
b'\x16'

>>> t2 = Temperature(b'\x20')
>>> print(t2.temp)
32
Temperature and humidity consisting of one signed byte for temperature and
one unsiged byte for humidity:
>>> class TempHum(BinmapDataclass):
... temp: signedchar = 0
... hum: unsignedchar = 0
...
>>> th = TempHum()
>>> th.temp = -10
>>> th.humidity = 60
>>> print(bytes(th))
b'\xfc<'

>>> th2 = TempHum(b'\xea\x41')
>>> print(th2.temp)
-22
>>> print(th2.hum)
65

Datatypes
Binmap supports all datatypes that standard library struct has.
The types works as typehints in the dataclass. When giving an attribute a
typehinted datatype it will be added to the binary output from the class.


Padding
Padding is a field type and datatype that is length bytes long, and will not show up as
attributes in the dataclass. Trying to assign it a value will be silently
ignored and reading from will raise the AttributeException exception.
>>> class PaddedData(BinmapDataclass):
... temp: signedchar = 0
... pad1: pad = padding(length = 5)
...
>>> pd = PaddedData()
>>> pd.temp = 14
>>> print(bytes(pd))
b'\x0e\x00\x00\x00\x00\x00'


Constant
Constant is fieldtype that always is the given value. Constant could be of any
datatype.
>>> class Constant(BinmapDataclass):
... signature: unsignedshort = constant(0x1313)
... temp: unsignedchar = 0
...
>>> c = Constant()
>>> c.temp = 18
>>> print(bytes(c))
b'\x13\x13\x12'

>>> print(c.signature)
4883
>>> print(c.temp)
18

>>> c.signature = 10
AttributeError: signature is a constant


Enums
Enumfield maps agaings IntEnum or IntFlag so that you could set the value
either as the enum or as the numeric value.
>>> class WindEnum(IntEnum):
... North = 0
... East = 1
... South = 2
... West = 3
...
>>> class Wind(BinmapDataclass):
... speed: unsignedchar = 0
... direction: unsignedchar = enumfield(WindEnum, default=WindEnum.East)
...
>>> w = Wind()
>>> print(w)
Wind(speed=0, direction=<WindEnum.East: 1>)
>>> w.direction = WindEnum.West
>>> print(w.direction)
<WindEnum.West: 3>
>>> w.direction = 2
>>> print(w.direction)
<WindEnum.South: 2>


Autolength
Autolenght field types counts number of bytes in the output, including the
autolength field it self. You can’t set an autolenght field. Autolength can be
offseted, for example to ignore it’s own length.
>>> class MyBinStruct(BinmapDataclass):
... length: unsignedchar = autolength()
... temp: signedchar = 0
...
>>> mb = MyBinStruct()
>>> print(mb)
MyBinStruct(length=2, temp=0)
>>> mb.length = 10
AttributeError: length is a constant


Calculated fields
Calculated fields calls a function when data is converted to binary value. The
function must be declared when the field is added.
>>> class WithChecksum(BinmapDataclass):
... temp: signedchar = 0
... hum: unsignedchar = 0
... def chk(self) -> unsignedchar:
... return (self.temp + self.hum) & 0xFF
... checksum: unsignedchar = calculatedfield(chk)
...
>>> wc = WithChecksum()
>>> wc.temp = -20
>>> wc.hum = 10
>>> print(wc)
WithChecksum(temp=-20, hum=10, checksum=246)
>>> print(bytes(wc))
b'\xec\n\xf6'