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# Copyright 2021-2022 Google LLC
#
# Licensed under the Apache License, Version 2.0 (the "License");
# you may not use this file except in compliance with the License.
# You may obtain a copy of the License at
#
# https://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS,
# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
# See the License for the specific language governing permissions and
# limitations under the License.
# -----------------------------------------------------------------------------
# Imports
# -----------------------------------------------------------------------------
from enum import IntEnum
import struct
from ..gatt_client import ProfileServiceProxy
from ..att import ATT_Error
from ..gatt import (
GATT_HEART_RATE_SERVICE,
GATT_HEART_RATE_MEASUREMENT_CHARACTERISTIC,
GATT_BODY_SENSOR_LOCATION_CHARACTERISTIC,
GATT_HEART_RATE_CONTROL_POINT_CHARACTERISTIC,
TemplateService,
Characteristic,
CharacteristicValue,
DelegatedCharacteristicAdapter,
PackedCharacteristicAdapter,
)
# -----------------------------------------------------------------------------
class HeartRateService(TemplateService):
UUID = GATT_HEART_RATE_SERVICE
HEART_RATE_CONTROL_POINT_FORMAT = 'B'
CONTROL_POINT_NOT_SUPPORTED = 0x80
RESET_ENERGY_EXPENDED = 0x01
class BodySensorLocation(IntEnum):
OTHER = 0
CHEST = 1
WRIST = 2
FINGER = 3
HAND = 4
EAR_LOBE = 5
FOOT = 6
class HeartRateMeasurement:
def __init__(
self,
heart_rate,
sensor_contact_detected=None,
energy_expended=None,
rr_intervals=None,
):
if heart_rate < 0 or heart_rate > 0xFFFF:
raise ValueError('heart_rate out of range')
if energy_expended is not None and (
energy_expended < 0 or energy_expended > 0xFFFF
):
raise ValueError('energy_expended out of range')
if rr_intervals:
for rr_interval in rr_intervals:
if rr_interval < 0 or rr_interval * 1024 > 0xFFFF:
raise ValueError('rr_intervals out of range')
self.heart_rate = heart_rate
self.sensor_contact_detected = sensor_contact_detected
self.energy_expended = energy_expended
self.rr_intervals = rr_intervals
@classmethod
def from_bytes(cls, data):
flags = data[0]
offset = 1
if flags & 1:
hr = struct.unpack_from('<H', data, offset)[0]
offset += 2
else:
hr = struct.unpack_from('B', data, offset)[0]
offset += 1
if flags & (1 << 2):
sensor_contact_detected = flags & (1 << 1) != 0
else:
sensor_contact_detected = None
if flags & (1 << 3):
energy_expended = struct.unpack_from('<H', data, offset)[0]
offset += 2
else:
energy_expended = None
if flags & (1 << 4):
rr_intervals = tuple(
struct.unpack_from('<H', data, offset + i * 2)[0] / 1024
for i in range((len(data) - offset) // 2)
)
else:
rr_intervals = ()
return cls(hr, sensor_contact_detected, energy_expended, rr_intervals)
def __bytes__(self):
if self.heart_rate < 256:
flags = 0
data = struct.pack('B', self.heart_rate)
else:
flags = 1
data = struct.pack('<H', self.heart_rate)
if self.sensor_contact_detected is not None:
flags |= ((1 if self.sensor_contact_detected else 0) << 1) | (1 << 2)
if self.energy_expended is not None:
flags |= 1 << 3
data += struct.pack('<H', self.energy_expended)
if self.rr_intervals:
flags |= 1 << 4
data += b''.join(
[
struct.pack('<H', int(rr_interval * 1024))
for rr_interval in self.rr_intervals
]
)
return bytes([flags]) + data
def __str__(self):
return (
f'HeartRateMeasurement(heart_rate={self.heart_rate},'
f' sensor_contact_detected={self.sensor_contact_detected},'
f' energy_expended={self.energy_expended},'
f' rr_intervals={self.rr_intervals})'
)
def __init__(
self,
read_heart_rate_measurement,
body_sensor_location=None,
reset_energy_expended=None,
):
self.heart_rate_measurement_characteristic = DelegatedCharacteristicAdapter(
Characteristic(
GATT_HEART_RATE_MEASUREMENT_CHARACTERISTIC,
Characteristic.Properties.NOTIFY,
0,
CharacteristicValue(read=read_heart_rate_measurement),
),
# pylint: disable=unnecessary-lambda
encode=lambda value: bytes(value),
)
characteristics = [self.heart_rate_measurement_characteristic]
if body_sensor_location is not None:
self.body_sensor_location_characteristic = Characteristic(
GATT_BODY_SENSOR_LOCATION_CHARACTERISTIC,
Characteristic.Properties.READ,
Characteristic.READABLE,
bytes([int(body_sensor_location)]),
)
characteristics.append(self.body_sensor_location_characteristic)
if reset_energy_expended:
def write_heart_rate_control_point_value(connection, value):
if value == self.RESET_ENERGY_EXPENDED:
if reset_energy_expended is not None:
reset_energy_expended(connection)
else:
raise ATT_Error(self.CONTROL_POINT_NOT_SUPPORTED)
self.heart_rate_control_point_characteristic = PackedCharacteristicAdapter(
Characteristic(
GATT_HEART_RATE_CONTROL_POINT_CHARACTERISTIC,
Characteristic.Properties.WRITE,
Characteristic.WRITEABLE,
CharacteristicValue(write=write_heart_rate_control_point_value),
),
pack_format=HeartRateService.HEART_RATE_CONTROL_POINT_FORMAT,
)
characteristics.append(self.heart_rate_control_point_characteristic)
super().__init__(characteristics)
# -----------------------------------------------------------------------------
class HeartRateServiceProxy(ProfileServiceProxy):
SERVICE_CLASS = HeartRateService
def __init__(self, service_proxy):
self.service_proxy = service_proxy
if characteristics := service_proxy.get_characteristics_by_uuid(
GATT_HEART_RATE_MEASUREMENT_CHARACTERISTIC
):
self.heart_rate_measurement = DelegatedCharacteristicAdapter(
characteristics[0],
decode=HeartRateService.HeartRateMeasurement.from_bytes,
)
else:
self.heart_rate_measurement = None
if characteristics := service_proxy.get_characteristics_by_uuid(
GATT_BODY_SENSOR_LOCATION_CHARACTERISTIC
):
self.body_sensor_location = DelegatedCharacteristicAdapter(
characteristics[0],
decode=lambda value: HeartRateService.BodySensorLocation(value[0]),
)
else:
self.body_sensor_location = None
if characteristics := service_proxy.get_characteristics_by_uuid(
GATT_HEART_RATE_CONTROL_POINT_CHARACTERISTIC
):
self.heart_rate_control_point = PackedCharacteristicAdapter(
characteristics[0],
pack_format=HeartRateService.HEART_RATE_CONTROL_POINT_FORMAT,
)
else:
self.heart_rate_control_point = None
async def reset_energy_expended(self):
if self.heart_rate_control_point is not None:
return await self.heart_rate_control_point.write_value(
HeartRateService.RESET_ENERGY_EXPENDED
)
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