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/*
* Copyright 2021 The Android Open Source Project
*
* 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
*
* http://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.
*/
#pragma once
#include <cstdint>
#include <optional>
#include "hci/address.h"
namespace rootcanal {
using ::bluetooth::hci::Address;
/*
* Notes about SCO / eSCO connection establishment:
*
* - Connections will always be established if possible as eSCO connections.
* The LMP parameter negotiation is skipped, instead the required parameters
* are directly sent to the peer.
*
* - If an synchronous connection setup fails with eSCO parameter negotiation,
* it is _not_ retried with SCO parameter negotiation.
*
* - If the parameters are compatible with the values returned from
* HCI Accept Synchronous Connection Request on the peer,
* the peer selects a valid link configuration which it returns
* in response.
*/
struct ScoLinkParameters {
uint8_t transmission_interval;
uint8_t retransmission_window;
uint16_t rx_packet_length;
uint16_t tx_packet_length;
uint8_t air_mode;
bool extended;
};
struct ScoConnectionParameters {
uint32_t transmit_bandwidth;
uint32_t receive_bandwidth;
uint16_t max_latency; // 0-3 reserved, 0xFFFF = don't care
uint16_t voice_setting;
uint8_t retransmission_effort;
uint16_t packet_type;
// Return true if packet_type enables extended SCO packets.
bool IsExtended();
// Return the link parameters for these connection parameters, if the
// parameters are coherent, none otherwise.
std::optional<ScoLinkParameters> GetLinkParameters();
};
enum ScoState {
SCO_STATE_CLOSED = 0,
SCO_STATE_PENDING,
SCO_STATE_SENT_ESCO_CONNECTION_REQUEST,
SCO_STATE_SENT_SCO_CONNECTION_REQUEST,
SCO_STATE_OPENED,
};
class ScoConnection {
public:
ScoConnection(Address address, ScoConnectionParameters const& parameters,
ScoState state, bool legacy = false)
: address_(address),
parameters_(parameters),
link_parameters_(),
state_(state),
legacy_(legacy) {}
virtual ~ScoConnection() = default;
bool IsLegacy() const { return legacy_; }
Address GetAddress() const { return address_; }
ScoState GetState() const { return state_; }
void SetState(ScoState state) { state_ = state; }
ScoConnectionParameters GetConnectionParameters() const {
return parameters_;
}
ScoLinkParameters GetLinkParameters() const { return link_parameters_; }
void SetLinkParameters(ScoLinkParameters const& parameters) {
link_parameters_ = parameters;
}
// Negotiate the connection parameters.
// Update the local connection parameters with negotiated values.
// Return true if the negotiation was successful, false otherwise.
bool NegotiateLinkParameters(ScoConnectionParameters const& peer);
private:
Address address_;
ScoConnectionParameters parameters_;
ScoLinkParameters link_parameters_;
ScoState state_;
// Mark connections opened with the HCI command Add SCO Connection.
// The connection status is reported with HCI Connection Complete event
// rather than HCI Synchronous Connection Complete event.
bool legacy_;
};
} // namespace rootcanal
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