Coverage for src / bluetooth_sig / gatt / characteristics / linear_position.py: 100%

1"""Linear Position characteristic implementation.""" 

2 

3from __future__ import annotations 

4 

5from ..context import CharacteristicContext 

6from .base import BaseCharacteristic 

7from .utils.data_parser import DataParser 

8 

9 

10class LinearPositionCharacteristic(BaseCharacteristic[float]): 

11 """Linear Position characteristic (0x2C08). 

12 

13 org.bluetooth.characteristic.linear_position 

14 

15 The Linear Position characteristic is used to represent the linear position of an object 

16 along a given axis and referencing to the device-specific zero point. 

17 """ 

18 

19 expected_length: int = 4 # sint32 

20 

21 def _decode_value(self, data: bytearray, ctx: CharacteristicContext | None = None) -> float | None: 

22 """Decode linear position characteristic. 

23 

24 Decodes a 32-bit signed integer representing position in 10^-7 m increments 

25 per Bluetooth SIG Linear Position characteristic specification. 

26 

27 Args: 

28 data: Raw bytes from BLE characteristic (exactly 4 bytes, little-endian) 

29 ctx: Optional context for parsing (device info, flags, etc.) 

30 

31 Returns: 

32 Position in meters, or None if value is not known 

33 

34 Raises: 

35 InsufficientDataError: If data is not exactly 4 bytes 

36 """ 

37 raw_value = DataParser.parse_int32(data, 0, signed=True) 

38 return raw_value * 1e-7 

39 

40 def _encode_value(self, data: float) -> bytearray: 

41 """Encode linear position value.""" 

42 raw_value = int(data / 1e-7) 

43 return DataParser.encode_int32(raw_value, signed=True)