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# Copyright 2024 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
# -----------------------------------------------------------------------------
import struct
from dataclasses import dataclass
from bumble import utils
from bumble.att import ATT_Error
from bumble.device import Connection
from bumble.gatt import (
GATT_AUDIO_LOCATION_CHARACTERISTIC,
GATT_AUDIO_OUTPUT_DESCRIPTION_CHARACTERISTIC,
GATT_VOLUME_OFFSET_CONTROL_POINT_CHARACTERISTIC,
GATT_VOLUME_OFFSET_CONTROL_SERVICE,
GATT_VOLUME_OFFSET_STATE_CHARACTERISTIC,
Characteristic,
CharacteristicValue,
TemplateService,
)
from bumble.gatt_adapters import (
DelegatedCharacteristicProxyAdapter,
SerializableCharacteristicProxyAdapter,
UTF8CharacteristicProxyAdapter,
)
from bumble.gatt_client import ProfileServiceProxy, ServiceProxy
from bumble.profiles.bap import AudioLocation
# -----------------------------------------------------------------------------
# Constants
# -----------------------------------------------------------------------------
MIN_VOLUME_OFFSET = -255
MAX_VOLUME_OFFSET = 255
CHANGE_COUNTER_MAX_VALUE = 0xFF
class SetVolumeOffsetOpCode(utils.OpenIntEnum):
SET_VOLUME_OFFSET = 0x01
class ErrorCode(utils.OpenIntEnum):
"""
See Volume Offset Control Service 1.6. Application error codes.
"""
INVALID_CHANGE_COUNTER = 0x80
OPCODE_NOT_SUPPORTED = 0x81
VALUE_OUT_OF_RANGE = 0x82
# -----------------------------------------------------------------------------
@dataclass
class VolumeOffsetState:
volume_offset: int = 0
change_counter: int = 0
attribute: Characteristic | None = None
def __bytes__(self) -> bytes:
return struct.pack('<hB', self.volume_offset, self.change_counter)
@classmethod
def from_bytes(cls, data: bytes):
volume_offset, change_counter = struct.unpack('<hB', data)
return cls(volume_offset, change_counter)
def increment_change_counter(self) -> None:
self.change_counter = (self.change_counter + 1) % (CHANGE_COUNTER_MAX_VALUE + 1)
async def notify_subscribers_via_connection(self, connection: Connection) -> None:
assert self.attribute is not None
await connection.device.notify_subscribers(attribute=self.attribute)
def on_read(self, _connection: Connection) -> bytes:
return bytes(self)
@dataclass
class VocsAudioLocation:
audio_location: AudioLocation = AudioLocation.NOT_ALLOWED
attribute: Characteristic | None = None
def __bytes__(self) -> bytes:
return struct.pack('<I', self.audio_location)
@classmethod
def from_bytes(cls, data: bytes):
audio_location = AudioLocation(struct.unpack('<I', data)[0])
return cls(audio_location)
def on_read(self, _connection: Connection) -> bytes:
return bytes(self)
async def on_write(self, connection: Connection, value: bytes) -> None:
assert self.attribute
self.audio_location = AudioLocation(int.from_bytes(value, 'little'))
await connection.device.notify_subscribers(attribute=self.attribute)
@dataclass
class VolumeOffsetControlPoint:
volume_offset_state: VolumeOffsetState
async def on_write(self, connection: Connection, value: bytes) -> None:
opcode = value[0]
if opcode != SetVolumeOffsetOpCode.SET_VOLUME_OFFSET:
raise ATT_Error(ErrorCode.OPCODE_NOT_SUPPORTED)
change_counter, volume_offset = struct.unpack('<Bh', value[1:])
await self._set_volume_offset(connection, change_counter, volume_offset)
async def _set_volume_offset(
self,
connection: Connection,
change_counter_operand: int,
volume_offset_operand: int,
) -> None:
change_counter = self.volume_offset_state.change_counter
if change_counter != change_counter_operand:
raise ATT_Error(ErrorCode.INVALID_CHANGE_COUNTER)
if not MIN_VOLUME_OFFSET <= volume_offset_operand <= MAX_VOLUME_OFFSET:
raise ATT_Error(ErrorCode.VALUE_OUT_OF_RANGE)
self.volume_offset_state.volume_offset = volume_offset_operand
self.volume_offset_state.increment_change_counter()
await self.volume_offset_state.notify_subscribers_via_connection(connection)
@dataclass
class AudioOutputDescription:
audio_output_description: str = ''
attribute: Characteristic | None = None
@classmethod
def from_bytes(cls, data: bytes):
return cls(audio_output_description=data.decode('utf-8'))
def __bytes__(self) -> bytes:
return self.audio_output_description.encode('utf-8')
def on_read(self, _connection: Connection) -> bytes:
return bytes(self)
async def on_write(self, connection: Connection, value: bytes) -> None:
assert self.attribute
self.audio_output_description = value.decode('utf-8')
await connection.device.notify_subscribers(attribute=self.attribute)
# -----------------------------------------------------------------------------
class VolumeOffsetControlService(TemplateService):
UUID = GATT_VOLUME_OFFSET_CONTROL_SERVICE
def __init__(
self,
volume_offset_state: VolumeOffsetState | None = None,
audio_location: VocsAudioLocation | None = None,
audio_output_description: AudioOutputDescription | None = None,
) -> None:
self.volume_offset_state = (
VolumeOffsetState() if volume_offset_state is None else volume_offset_state
)
self.audio_location = (
VocsAudioLocation() if audio_location is None else audio_location
)
self.audio_output_description = (
AudioOutputDescription()
if audio_output_description is None
else audio_output_description
)
self.volume_offset_control_point: VolumeOffsetControlPoint = (
VolumeOffsetControlPoint(self.volume_offset_state)
)
self.volume_offset_state_characteristic: Characteristic[bytes] = Characteristic(
uuid=GATT_VOLUME_OFFSET_STATE_CHARACTERISTIC,
properties=(
Characteristic.Properties.READ | Characteristic.Properties.NOTIFY
),
permissions=Characteristic.Permissions.READ_REQUIRES_ENCRYPTION,
value=CharacteristicValue(read=self.volume_offset_state.on_read),
)
self.audio_location_characteristic: Characteristic[bytes] = Characteristic(
uuid=GATT_AUDIO_LOCATION_CHARACTERISTIC,
properties=(
Characteristic.Properties.READ
| Characteristic.Properties.NOTIFY
| Characteristic.Properties.WRITE_WITHOUT_RESPONSE
),
permissions=(
Characteristic.Permissions.READ_REQUIRES_ENCRYPTION
| Characteristic.Permissions.WRITE_REQUIRES_ENCRYPTION
),
value=CharacteristicValue(
read=self.audio_location.on_read,
write=self.audio_location.on_write,
),
)
self.audio_location.attribute = self.audio_location_characteristic
self.volume_offset_control_point_characteristic: Characteristic[bytes] = (
Characteristic(
uuid=GATT_VOLUME_OFFSET_CONTROL_POINT_CHARACTERISTIC,
properties=Characteristic.Properties.WRITE,
permissions=Characteristic.Permissions.WRITE_REQUIRES_ENCRYPTION,
value=CharacteristicValue(
write=self.volume_offset_control_point.on_write
),
)
)
self.audio_output_description_characteristic: Characteristic[bytes] = (
Characteristic(
uuid=GATT_AUDIO_OUTPUT_DESCRIPTION_CHARACTERISTIC,
properties=(
Characteristic.Properties.READ
| Characteristic.Properties.NOTIFY
| Characteristic.Properties.WRITE_WITHOUT_RESPONSE
),
permissions=(
Characteristic.Permissions.READ_REQUIRES_ENCRYPTION
| Characteristic.Permissions.WRITE_REQUIRES_ENCRYPTION
),
value=CharacteristicValue(
read=self.audio_output_description.on_read,
write=self.audio_output_description.on_write,
),
)
)
self.audio_output_description.attribute = (
self.audio_output_description_characteristic
)
super().__init__(
characteristics=[
self.volume_offset_state_characteristic, # type: ignore
self.audio_location_characteristic, # type: ignore
self.volume_offset_control_point_characteristic, # type: ignore
self.audio_output_description_characteristic, # type: ignore
],
primary=False,
)
# -----------------------------------------------------------------------------
# Client
# -----------------------------------------------------------------------------
class VolumeOffsetControlServiceProxy(ProfileServiceProxy):
SERVICE_CLASS = VolumeOffsetControlService
def __init__(self, service_proxy: ServiceProxy) -> None:
self.service_proxy = service_proxy
self.volume_offset_state = SerializableCharacteristicProxyAdapter(
service_proxy.get_required_characteristic_by_uuid(
GATT_VOLUME_OFFSET_STATE_CHARACTERISTIC
),
VolumeOffsetState,
)
self.audio_location = DelegatedCharacteristicProxyAdapter(
service_proxy.get_required_characteristic_by_uuid(
GATT_AUDIO_LOCATION_CHARACTERISTIC
),
encode=lambda value: bytes([int(value)]),
decode=lambda data: AudioLocation(data[0]),
)
self.volume_offset_control_point = (
service_proxy.get_required_characteristic_by_uuid(
GATT_VOLUME_OFFSET_CONTROL_POINT_CHARACTERISTIC
)
)
self.audio_output_description = UTF8CharacteristicProxyAdapter(
service_proxy.get_required_characteristic_by_uuid(
GATT_AUDIO_OUTPUT_DESCRIPTION_CHARACTERISTIC
)
)
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