Ewout van Bekkum | 1c7c83f | 2021-08-05 11:13:44 -0700 | [diff] [blame] | 1 | // Copyright 2021 The Pigweed Authors |
| 2 | // |
| 3 | // Licensed under the Apache License, Version 2.0 (the "License"); you may not |
| 4 | // use this file except in compliance with the License. You may obtain a copy of |
| 5 | // the License at |
| 6 | // |
| 7 | // https://www.apache.org/licenses/LICENSE-2.0 |
| 8 | // |
| 9 | // Unless required by applicable law or agreed to in writing, software |
| 10 | // distributed under the License is distributed on an "AS IS" BASIS, WITHOUT |
| 11 | // WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the |
| 12 | // License for the specific language governing permissions and limitations under |
| 13 | // the License. |
| 14 | #include "pw_bluetooth_hci/uart_transport.h" |
| 15 | |
| 16 | namespace pw::bluetooth_hci { |
| 17 | |
| 18 | StatusWithSize DecodeHciUartData(ConstByteSpan data, |
| 19 | const DecodedPacketCallback& packet_callback) { |
| 20 | size_t bytes_consumed = 0; |
| 21 | while (data.size_bytes() > 0) { |
| 22 | const std::byte packet_indicator = data[0]; |
| 23 | data = data.subspan(1); // Pop off the packet indicator byte. |
| 24 | // Note that we do not yet claim the byte consumed until we know what it is, |
| 25 | // as it may be a partial HCI packet which cannot be consumed until later. |
| 26 | |
| 27 | size_t packet_size_bytes = 0; |
| 28 | switch (packet_indicator) { |
| 29 | case kUartCommandPacketIndicator: { |
| 30 | const std::optional<CommandPacket> maybe_packet = |
| 31 | CommandPacket::Decode(data, std::endian::little); |
| 32 | if (!maybe_packet.has_value()) { |
| 33 | return StatusWithSize( |
| 34 | bytes_consumed); // Not enough data to complete this packet. |
| 35 | } |
| 36 | |
| 37 | const CommandPacket& packet = maybe_packet.value(); |
| 38 | packet_callback(packet); |
| 39 | packet_size_bytes = packet.size_bytes(); |
| 40 | break; |
| 41 | } |
| 42 | |
| 43 | case kUartAsyncDataPacketIndicator: { |
| 44 | const std::optional<AsyncDataPacket> maybe_packet = |
| 45 | AsyncDataPacket::Decode(data, std::endian::little); |
| 46 | if (!maybe_packet.has_value()) { |
| 47 | return StatusWithSize( |
| 48 | bytes_consumed); // Not enough data to complete this packet. |
| 49 | } |
| 50 | |
| 51 | const AsyncDataPacket& packet = maybe_packet.value(); |
| 52 | packet_callback(packet); |
| 53 | packet_size_bytes = packet.size_bytes(); |
| 54 | break; |
| 55 | } |
| 56 | |
| 57 | case kUartSyncDataPacketIndicator: { |
| 58 | const std::optional<SyncDataPacket> maybe_packet = |
| 59 | SyncDataPacket::Decode(data, std::endian::little); |
| 60 | if (!maybe_packet.has_value()) { |
| 61 | return StatusWithSize( |
| 62 | bytes_consumed); // Not enough data to complete this packet. |
| 63 | } |
| 64 | |
| 65 | const SyncDataPacket& packet = maybe_packet.value(); |
| 66 | packet_callback(packet); |
| 67 | packet_size_bytes = packet.size_bytes(); |
| 68 | break; |
| 69 | } |
| 70 | |
| 71 | case kUartEventPacketIndicator: { |
| 72 | const std::optional<EventPacket> maybe_packet = |
| 73 | EventPacket::Decode(data); |
| 74 | if (!maybe_packet.has_value()) { |
| 75 | return StatusWithSize( |
| 76 | bytes_consumed); // Not enough data to complete this packet. |
| 77 | } |
| 78 | |
| 79 | const EventPacket& packet = maybe_packet.value(); |
| 80 | packet_callback(packet); |
| 81 | packet_size_bytes = packet.size_bytes(); |
| 82 | break; |
| 83 | } |
| 84 | |
| 85 | default: |
| 86 | // Unrecognized PacketIndicator type, we've lost synchronization! |
| 87 | ++bytes_consumed; // Consume the invalid packet indicator. |
| 88 | return StatusWithSize::DataLoss(bytes_consumed); |
| 89 | } |
| 90 | |
| 91 | data = data.subspan(packet_size_bytes); // Pop off the HCI packet. |
| 92 | // Consume the packet indicator and the packet. |
| 93 | bytes_consumed += 1 + packet_size_bytes; |
| 94 | } |
| 95 | return StatusWithSize(bytes_consumed); |
| 96 | } |
| 97 | |
| 98 | } // namespace pw::bluetooth_hci |