bluetooth/hci_protocol.cc

//
// Copyright 2017 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.
//

#include "hci_protocol.h"

#define LOG_TAG "android.hardware.bluetooth-hci-hci_protocol"
#include <android-base/logging.h>
#include <assert.h>
#include <fcntl.h>
#include <utils/Log.h>

namespace {

const size_t preamble_size_for_type[] = {
    0, HCI_COMMAND_PREAMBLE_SIZE, HCI_ACL_PREAMBLE_SIZE, HCI_SCO_PREAMBLE_SIZE,
    HCI_EVENT_PREAMBLE_SIZE};
const size_t packet_length_offset_for_type[] = {
    0, HCI_LENGTH_OFFSET_CMD, HCI_LENGTH_OFFSET_ACL, HCI_LENGTH_OFFSET_SCO,
    HCI_LENGTH_OFFSET_EVT};

size_t HciGetPacketLengthForType(HciPacketType type, const uint8_t* preamble) {
  size_t offset = packet_length_offset_for_type[type];
  if (type != HCI_PACKET_TYPE_ACL_DATA) return preamble[offset];
  return (((preamble[offset + 1]) << 8) | preamble[offset]);
}

}  // namespace

namespace android {
namespace hardware {
namespace bluetooth {
namespace hci {

size_t HciProtocol::WriteSafely(int fd, const uint8_t* data, size_t length) {
  size_t transmitted_length = 0;
  while (length > 0) {
    ssize_t ret =
        TEMP_FAILURE_RETRY(write(fd, data + transmitted_length, length));

    if (ret == -1) {
      if (errno == EAGAIN) continue;
      ALOGE("%s error writing to UART (%s)", __func__, strerror(errno));
      break;

    } else if (ret == 0) {
      // Nothing written :(
      ALOGE("%s zero bytes written - something went wrong...", __func__);
      break;
    }

    transmitted_length += ret;
    length -= ret;
  }

  return transmitted_length;
}

}  // namespace hci
}  // namespace bluetooth
}  // namespace hardware
}  // namespace android