BT HAL H4 write flow

#define LOG_TAG "android.hardware.bluetooth-hci-h4"

#include <android-base/logging.h>

#include <assert.h>

#include <errno.h>

#include <fcntl.h>

#include <log/log.h>

#include <sys/uio.h>

namespace android {

namespace hardware {

namespace hci {

size_t H4Protocol::Send(uint8_t type, const uint8_t* data, size_t length) {

  int rv = WriteSafely(uart_fd_, &type, sizeof(type));

  if (rv == sizeof(type)) {

    rv = WriteSafely(uart_fd_, data, length);

  struct iovec iov[] = {{&type, sizeof(type)},

                        {const_cast<uint8_t*>(data), length}};

  ssize_t ret = 0;

  do {

    ret = TEMP_FAILURE_RETRY(writev(uart_fd_, iov, sizeof(iov) / sizeof(iov[0])));

  } while (-1 == ret && EAGAIN == errno);

  if (ret == -1) {

    ALOGE("%s error writing to UART (%s)", __func__, strerror(errno));

  } else if (ret == 0) {

    // Nothing written :(

    ALOGE("%s zero bytes written - something went wrong...", __func__);

  }

  return rv;

  return ret;

}

void H4Protocol::OnPacketReady() {