text: /**
   *  @file LoRaPHUS915.cpp
   *
   *  @brief Implements LoRaPHY for US 915 MHz band
   *
   *  \code
   *   ______                              _
   *  / _____)             _              | |
   * ( (____  _____ ____ _| |_ _____  ____| |__
   *  \____ \| ___ |    (_   _) ___ |/ ___)  _ \
   *  _____) ) ____| | | || |_| ____( (___| | | |
   * (______/|_____)_|_|_| \__)_____)\____)_| |_|
   *   (C)2013 Semtech
   *  ___ _____ _   ___ _  _____ ___  ___  ___ ___
   * / __|_   _/_\ / __| |/ / __/ _ \| _ \/ __| __|
   * \__ \ | |/ _ \ (__| ' <| _| (_) |   / (__| _|
   * |___/ |_/_/ \_\___|_|\_\_| \___/|_|_\\___|___|
   * embedded.connectivity.solutions===============
   *
   * \endcode
   *
   *
   * License: Revised BSD License, see LICENSE.TXT file include in the project
   *
   * Maintainer: Miguel Luis ( Semtech ), Gregory Cristian ( Semtech ) and Daniel Jaeckle ( STACKFORCE )
   *
   * Copyright (c) 2017, Arm Limited and affiliates.
   * SPDX-License-Identifier: BSD-3-Clause
   *
   */
  
  #include "LoRaPHYUS915.h"
  #include "lora_phy_ds.h"
  
  
  /*!
   * Minimal datarate that can be used by the node
   */
  #define US915_TX_MIN_DATARATE                       DR_0
  
  /*!
   * Maximal datarate that can be used by the node
   */
  #define US915_TX_MAX_DATARATE                       DR_4
  
  /*!
   * Minimal datarate that can be used by the node
   */
  #define US915_RX_MIN_DATARATE                       DR_8
  
  /*!
   * Maximal datarate that can be used by the node
   */
  #define US915_RX_MAX_DATARATE                       DR_13
  
  /*!
   * Default datarate used by the node
   */
  #define US915_DEFAULT_DATARATE                      DR_0
  
  /*!
   * Minimal Rx1 receive datarate offset
   */
  #define US915_MIN_RX1_DR_OFFSET                     0
  
  /*!
   * Maximal Rx1 receive datarate offset
   */
  #define US915_MAX_RX1_DR_OFFSET                     3
  
  /*!
   * Default Rx1 receive datarate offset
   */
  #define US915_DEFAULT_RX1_DR_OFFSET                 0
  
  /*!
   * Minimal Tx output power that can be used by the node
   */
  #define US915_MIN_TX_POWER                          TX_POWER_10
  
  /*!
   * Maximal Tx output power that can be used by the node
   */
  #define US915_MAX_TX_POWER                          TX_POWER_0
  
  /*!
   * Default Tx output power used by the node
   */
  #define US915_DEFAULT_TX_POWER                      TX_POWER_0
  
  /*!
   * Default Max ERP
   */
  #define US915_DEFAULT_MAX_ERP                      30.0f
  
  /*!
   * ADR Ack limit
   */
  #define US915_ADR_ACK_LIMIT                         64
  
  /*!
   * ADR Ack delay
   */
  #define US915_ADR_ACK_DELAY                         32
  
  /*!
   * Enabled or disabled the duty cycle
   */
  #define US915_DUTY_CYCLE_ENABLED                    0
  
  /*!
   * Maximum RX window duration
   */
  #define US915_MAX_RX_WINDOW                         3000
  
  /*!
   * Receive delay 1
   */
  #define US915_RECEIVE_DELAY1                        1000
  
  /*!
   * Receive delay 2
   */
  #define US915_RECEIVE_DELAY2                        2000
  
  /*!
   * Join accept delay 1
   */
  #define US915_JOIN_ACCEPT_DELAY1                    5000
  
  /*!
   * Join accept delay 2
   */
  #define US915_JOIN_ACCEPT_DELAY2                    6000
  
  /*!
   * Maximum frame counter gap
   */
  #define US915_MAX_FCNT_GAP                          16384
  
  /*!
   * Ack timeout
   */
  #define US915_ACKTIMEOUT                            2000
  
  /*!
   * Random ack timeout limits
   */
  #define US915_ACK_TIMEOUT_RND                       1000
  
  /*!
   * Second reception window channel frequency definition.
   */
  #define US915_RX_WND_2_FREQ                         923300000
  
  /*!
   * Second reception window channel datarate definition.
   */
  #define US915_RX_WND_2_DR                           DR_8
  
  /*!
   * Band 0 definition
   * { DutyCycle, TxMaxPower, LastJoinTxDoneTime, LastTxDoneTime, TimeOff }
   */
  static const band_t US915_BAND0 = { 1, US915_MAX_TX_POWER, 0, 0, 0 }; //  100.0 %
  
  /*!
   * Defines the first channel for RX window 1 for US band
   */
  #define US915_FIRST_RX1_CHANNEL                     ( (uint32_t) 923300000 )
  
  /*!
   * Defines the last channel for RX window 1 for US band
   */
  #define US915_LAST_RX1_CHANNEL                      ( (uint32_t) 927500000 )
  
  /*!
   * Defines the step width of the channels for RX window 1
   */
  #define US915_STEPWIDTH_RX1_CHANNEL                 ( (uint32_t) 600000 )
  
  /*!
   * Data rates table definition
   */
  static const uint8_t datarates_US915[]  = {10, 9, 8,  7,  8,  0,  0, 0, 12, 11, 10, 9, 8, 7, 0, 0};
  
  /*!
   * Bandwidths table definition in Hz
   */
  static const uint32_t bandwidths_US915[] = {125000, 125000, 125000, 125000, 500000, 0, 0, 0, 500000, 500000, 500000, 500000, 500000, 500000, 0, 0};
  
  /*!
   * Up/Down link data rates offset definition
   */
  static const int8_t datarate_offsets_US915[5][4] = {
      { DR_10, DR_9, DR_8, DR_8  },   // DR_0
      { DR_11, DR_10, DR_9, DR_8  },  // DR_1
      { DR_12, DR_11, DR_10, DR_9  }, // DR_2
      { DR_13, DR_12, DR_11, DR_10 }, // DR_3
      { DR_13, DR_13, DR_12, DR_11 }, // DR_4
  };
  
  /*!
   * Maximum payload with respect to the datarate index. Cannot operate with repeater.
   */
  static const uint8_t max_payloads_US915[] = {11, 53, 125, 242, 242, 0, 0, 0, 53, 129, 242, 242, 242, 242, 0, 0};
  
  /*!
   * Maximum payload with respect to the datarate index. Can operate with repeater.
   */
  static const uint8_t max_payloads_with_repeater_US915[] = {11, 53, 125, 242, 242, 0, 0, 0, 33, 109, 222, 222, 222, 222, 0, 0};
  
  static const uint16_t fsb_mask[] = MBED_CONF_LORA_FSB_MASK;
  static const uint16_t full_channel_mask [] = {0xFFFF, 0xFFFF, 0xFFFF, 0xFFFF, 0x00FF};
  
  LoRaPHYUS915::LoRaPHYUS915()
  {
      bands[0] = US915_BAND0;
  
      // Channels
      // 125 kHz channels - Upstream
      for (uint8_t i = 0; i < US915_MAX_NB_CHANNELS - 8; i++) {
          channels[i].frequency = 902300000 + i * 200000;
          channels[i].dr_range.value = (DR_3 << 4) | DR_0;
          channels[i].band = 0;
      }
      // 500 kHz channels - Upstream
      for (uint8_t i = US915_MAX_NB_CHANNELS - 8; i < US915_MAX_NB_CHANNELS; i++) {
          channels[i].frequency = 903000000 + (i - (US915_MAX_NB_CHANNELS - 8)) * 1600000;
          channels[i].dr_range.value = (DR_4 << 4) | DR_4;
          channels[i].band = 0;
      }
  
      // Fill-up default channel mask and apply FSB mask too
      fill_channel_mask_with_fsb(full_channel_mask, fsb_mask,
                                 default_channel_mask, US915_CHANNEL_MASK_SIZE);
  
      memset(channel_mask, 0, sizeof(channel_mask));
      memset(current_channel_mask, 0, sizeof(current_channel_mask));
  
      // Copy channels default mask
      copy_channel_mask(channel_mask, default_channel_mask, US915_CHANNEL_MASK_SIZE);
  
      // current channel masks keep track of the
      // channels previously used, i.e., which channels should be avoided in
      // next transmission
      copy_channel_mask(current_channel_mask, channel_mask, US915_CHANNEL_MASK_SIZE);
  
      // set default channels
      phy_params.channels.channel_list = channels;
      phy_params.channels.channel_list_size = US915_MAX_NB_CHANNELS;
      phy_params.channels.mask = channel_mask;
      phy_params.channels.default_mask = default_channel_mask;
      phy_params.channels.mask_size = US915_CHANNEL_MASK_SIZE;
  
      // set bands for US915 spectrum
      phy_params.bands.table = (void *) bands;
      phy_params.bands.size = US915_MAX_NB_BANDS;
  
      // set bandwidths available in US915 spectrum
      phy_params.bandwidths.table = (void *) bandwidths_US915;
      phy_params.bandwidths.size = 16;
  
      // set data rates available in US915 spectrum
      phy_params.datarates.table = (void *) datarates_US915;
      phy_params.datarates.size = 16;
  
      // set payload sizes with respect to data rates
      phy_params.payloads.table = (void *) max_payloads_US915;
      phy_params.payloads.size = 16;
      phy_params.payloads_with_repeater.table = (void *) max_payloads_with_repeater_US915;
      phy_params.payloads_with_repeater.size = 16;
  
      // dwell time setting
      phy_params.ul_dwell_time_setting = 0;
      phy_params.dl_dwell_time_setting = 0;
  
      // set initial and default parameters
      phy_params.duty_cycle_enabled = US915_DUTY_CYCLE_ENABLED;
      phy_params.accept_tx_param_setup_req = false;
      phy_params.fsk_supported = false;
      phy_params.cflist_supported = false;
      phy_params.dl_channel_req_supported = false;
      phy_params.custom_channelplans_supported = false;
      phy_params.default_channel_cnt = US915_MAX_NB_CHANNELS;
      phy_params.max_channel_cnt = US915_MAX_NB_CHANNELS;
      phy_params.cflist_channel_cnt = 0;
      phy_params.min_tx_datarate = US915_TX_MIN_DATARATE;
      phy_params.max_tx_datarate = US915_TX_MAX_DATARATE;
      phy_params.min_rx_datarate = US915_RX_MIN_DATARATE;
      phy_params.max_rx_datarate = US915_RX_MAX_DATARATE;
      phy_params.default_datarate = US915_DEFAULT_DATARATE;
      phy_params.default_max_datarate = US915_TX_MAX_DATARATE;
      phy_params.min_rx1_dr_offset = US915_MIN_RX1_DR_OFFSET;
      phy_params.max_rx1_dr_offset = US915_MAX_RX1_DR_OFFSET;
      phy_params.default_rx1_dr_offset = US915_DEFAULT_RX1_DR_OFFSET;
      phy_params.min_tx_power = US915_MIN_TX_POWER;
      phy_params.max_tx_power = US915_MAX_TX_POWER;
      phy_params.default_tx_power = US915_DEFAULT_TX_POWER;
      phy_params.default_max_eirp = 0;
      phy_params.default_antenna_gain = 0;
      phy_params.adr_ack_limit = US915_ADR_ACK_LIMIT;
      phy_params.adr_ack_delay = US915_ADR_ACK_DELAY;
      phy_params.max_rx_window = US915_MAX_RX_WINDOW;
      phy_params.recv_delay1 = US915_RECEIVE_DELAY1;
      phy_params.recv_delay2 = US915_RECEIVE_DELAY2;
  
      phy_params.join_accept_delay1 = US915_JOIN_ACCEPT_DELAY1;
      phy_params.join_accept_delay2 = US915_JOIN_ACCEPT_DELAY2;
      phy_params.max_fcnt_gap = US915_MAX_FCNT_GAP;
      phy_params.ack_timeout = US915_ACKTIMEOUT;
      phy_params.ack_timeout_rnd = US915_ACK_TIMEOUT_RND;
      phy_params.rx_window2_datarate = US915_RX_WND_2_DR;
      phy_params.rx_window2_frequency = US915_RX_WND_2_FREQ;
  }
  
  LoRaPHYUS915::~LoRaPHYUS915()
  {
  }
  
  int8_t LoRaPHYUS915::limit_tx_power(int8_t tx_power, int8_t max_band_tx_power,
                                      int8_t datarate)
  {
      int8_t tx_power_out = tx_power;
  
      // Limit tx power to the band max
      tx_power_out =  MAX(tx_power, max_band_tx_power);
  
      if (datarate == DR_4) {
          // Limit tx power to max 26dBm
          tx_power_out = MAX(tx_power, TX_POWER_2);
      } else {
  
          if (num_active_channels(channel_mask, 0, 4) < 50) {
              // Limit tx power to max 21dBm
              tx_power_out = MAX(tx_power, TX_POWER_5);
          }
      }
  
      return tx_power_out;
  }
  
  void LoRaPHYUS915::restore_default_channels()
  {
      // Copy channels default mask
      copy_channel_mask(channel_mask, default_channel_mask, US915_CHANNEL_MASK_SIZE);
  
      // Update running channel mask
      intersect_channel_mask(channel_mask, current_channel_mask, US915_CHANNEL_MASK_SIZE);
  }
  
  bool LoRaPHYUS915::rx_config(rx_config_params_t *config)
  {
      int8_t dr = config->datarate;
      uint8_t max_payload = 0;
      int8_t phy_dr = 0;
      uint32_t frequency = config->frequency;
  
      _radio->lock();
  
      if (_radio->get_status() != RF_IDLE) {
  
          _radio->unlock();
          return false;
  
      }
  
      _radio->unlock();
  
      // For US915 spectrum, we have 8 Downstream channels, MAC would have
      // selected a channel randomly from 72 Upstream channels, that index is
      // passed in rx_config_params_t. Based on that channel index, we choose the
      // frequency for first RX slot
      if (config->rx_slot == RX_SLOT_WIN_1) {
          // Apply window 1 frequency
          frequency = US915_FIRST_RX1_CHANNEL + (config->channel % 8) * US915_STEPWIDTH_RX1_CHANNEL;
      }
  
      // Read the physical datarate from the datarates table
      phy_dr = datarates_US915[dr];
  
      _radio->lock();
  
      _radio->set_channel(frequency);
  
      // Radio configuration
      _radio->set_rx_config(MODEM_LORA, config->bandwidth, phy_dr, 1, 0,
                            MBED_CONF_LORA_DOWNLINK_PREAMBLE_LENGTH,
                            config->window_timeout, false, 0, false, 0, 0, true,
                            config->is_rx_continuous);
      _radio->unlock();
  
      if (config->is_repeater_supported == true) {
  
          max_payload = max_payloads_with_repeater_US915[dr];
  
      } else {
  
          max_payload = max_payloads_US915[dr];
  
      }
  
      _radio->lock();
  
      _radio->set_max_payload_length(MODEM_LORA, max_payload + LORA_MAC_FRMPAYLOAD_OVERHEAD);
  
      _radio->unlock();
  
      return true;
  }
  
  bool LoRaPHYUS915::tx_config(tx_config_params_t *config, int8_t *tx_power,
                               lorawan_time_t *tx_toa)
  {
      int8_t phy_dr = datarates_US915[config->datarate];
      int8_t tx_power_limited = limit_tx_power(config->tx_power,
                                               bands[channels[config->channel].band].max_tx_pwr,
                                               config->datarate);
  
      uint32_t bandwidth = get_bandwidth(config->datarate);
      int8_t phy_tx_power = 0;
  
      // Calculate physical TX power
      phy_tx_power = compute_tx_power(tx_power_limited, US915_DEFAULT_MAX_ERP, 0);
  
      _radio->lock();
  
      _radio->set_channel(channels[config->channel].frequency);
  
      _radio->set_tx_config(MODEM_LORA, phy_tx_power, 0, bandwidth, phy_dr, 1,
                            MBED_CONF_LORA_UPLINK_PREAMBLE_LENGTH,
                            false, true, 0, 0, false, 3000);
  
      // Setup maximum payload lenght of the radio driver
      _radio->set_max_payload_length(MODEM_LORA, config->pkt_len);
  
      // Get the time-on-air of the next tx frame
      *tx_toa = _radio->time_on_air(MODEM_LORA, config->pkt_len);
  
      _radio->unlock();
  
      *tx_power = tx_power_limited;
  
      return true;
  }
  
  uint8_t LoRaPHYUS915::link_ADR_request(adr_req_params_t *params,
                                         int8_t *dr_out, int8_t *tx_power_out,
                                         uint8_t *nb_rep_out, uint8_t *nb_bytes_parsed)
  {
      uint8_t status = 0x07;
  
      link_adr_params_t adr_settings;
      uint8_t next_idx = 0;
      uint8_t bytes_processed = 0;
      uint16_t temp_channel_masks[US915_CHANNEL_MASK_SIZE] = {0, 0, 0, 0, 0};
  
      verify_adr_params_t verify_params;
  
      // Initialize local copy of channels mask
      copy_channel_mask(temp_channel_masks, channel_mask, US915_CHANNEL_MASK_SIZE);
  
      while (bytes_processed < params->payload_size &&
              params->payload[bytes_processed] == SRV_MAC_LINK_ADR_REQ) {
          next_idx = parse_link_ADR_req(&(params->payload[bytes_processed]),
                                        params->payload_size - bytes_processed,
                                        &adr_settings);
  
          if (next_idx == 0) {
              bytes_processed = 0;
              // break loop, malformed packet
              break;
          }
  
          // Update bytes processed
          bytes_processed += next_idx;
  
          // Revert status, as we only check the last ADR request for the channel mask KO
          status = 0x07;
  
          if (adr_settings.ch_mask_ctrl == 6) {
  
              // Enable all 125 kHz channels
              fill_channel_mask_with_value(temp_channel_masks, 0xFFFF,
                                           US915_CHANNEL_MASK_SIZE - 1);
  
              // Apply chMask to channels 64 to 71
              temp_channel_masks[4] = adr_settings.channel_mask;
  
          } else if (adr_settings.ch_mask_ctrl == 7) {
  
              // Disable all 125 kHz channels
              fill_channel_mask_with_value(temp_channel_masks, 0x0000,
                                           US915_CHANNEL_MASK_SIZE - 1);
  
              // Apply chMask to channels 64 to 71
              temp_channel_masks[4] = adr_settings.channel_mask;
  
          } else if (adr_settings.ch_mask_ctrl == 5) {
              // RFU
              status &= 0xFE; // Channel mask KO
  
          } else {
              temp_channel_masks[adr_settings.ch_mask_ctrl] = adr_settings.channel_mask;
          }
      }
  
      if (bytes_processed == 0) {
          *nb_bytes_parsed = 0;
          return status;
      }
  
      // FCC 15.247 paragraph F mandates to hop on at least 2 125 kHz channels
      if ((adr_settings.datarate < DR_4) &&
              (num_active_channels(temp_channel_masks, 0, 4) < 2)) {
  
          status &= 0xFE; // Channel mask KO
  
      }
  
      verify_params.status = status;
      verify_params.adr_enabled = params->adr_enabled;
      verify_params.datarate = adr_settings.datarate;
      verify_params.tx_power = adr_settings.tx_power;
      verify_params.nb_rep = adr_settings.nb_rep;
      verify_params.current_datarate = params->current_datarate;
      verify_params.current_tx_power = params->current_tx_power;
      verify_params.current_nb_rep = params->current_nb_trans;
      verify_params.channel_mask = temp_channel_masks;
  
      // Verify the parameters and update, if necessary
      status = verify_link_ADR_req(&verify_params, &adr_settings.datarate,
                                   &adr_settings.tx_power, &adr_settings.nb_rep);
  
      // Update channelsMask if everything is correct
      if (status == 0x07) {
          // Copy Mask
          copy_channel_mask(channel_mask, temp_channel_masks, US915_CHANNEL_MASK_SIZE);
  
          // update running channel mask
          intersect_channel_mask(channel_mask, current_channel_mask,
                                 US915_CHANNEL_MASK_SIZE);
      }
  
      // Update status variables
      *dr_out = adr_settings.datarate;
      *tx_power_out = adr_settings.tx_power;
      *nb_rep_out = adr_settings.nb_rep;
      *nb_bytes_parsed = bytes_processed;
  
      return status;
  }
  
  uint8_t LoRaPHYUS915::accept_rx_param_setup_req(rx_param_setup_req_t *params)
  {
      uint8_t status = 0x07;
      uint32_t freq = params->frequency;
  
      // Verify radio frequency
      if ((_radio->check_rf_frequency(freq) == false)
              || (freq < US915_FIRST_RX1_CHANNEL)
              || (freq > US915_LAST_RX1_CHANNEL)
              || (((freq - (uint32_t) US915_FIRST_RX1_CHANNEL) % (uint32_t) US915_STEPWIDTH_RX1_CHANNEL) != 0)) {
  
          status &= 0xFE; // Channel frequency KO
  
      }
  
      // Verify datarate
      if (val_in_range(params->datarate, US915_RX_MIN_DATARATE, US915_RX_MAX_DATARATE) == 0) {
  
          status &= 0xFD; // Datarate KO
  
      }
  
      if ((val_in_range(params->datarate, DR_5, DR_7)) || (params->datarate > DR_13)) {
  
          status &= 0xFD; // Datarate KO
  
      }
  
      // Verify datarate offset
      if (val_in_range(params->dr_offset, US915_MIN_RX1_DR_OFFSET, US915_MAX_RX1_DR_OFFSET) == 0) {
          status &= 0xFB; // Rx1DrOffset range KO
      }
  
      return status;
  }
  
  int8_t LoRaPHYUS915::get_alternate_DR(uint8_t nb_trials)
  {
      int8_t datarate = 0;
  
      if ((nb_trials & 0x01) == 0x01) {
          datarate = DR_4;
      } else {
          datarate = DR_0;
      }
  
      return datarate;
  }
  
  lorawan_status_t LoRaPHYUS915::set_next_channel(channel_selection_params_t *params,
                                                  uint8_t *channel, lorawan_time_t *time,
                                                  lorawan_time_t *aggregate_timeOff)
  {
      uint8_t nb_enabled_channels = 0;
      uint8_t delay_tx = 0;
      uint8_t enabled_channels[US915_MAX_NB_CHANNELS] = {0};
      lorawan_time_t next_tx_delay = 0;
  
      // Count 125kHz channels
      if (num_active_channels(current_channel_mask, 0, 4) == 0) {
          // If none of the 125 kHz Upstream channel found,
          // Reactivate default channels
          copy_channel_mask(current_channel_mask, channel_mask, 4);
      }
  
      // Update the 500 kHz channels in the running mask
      if ((params->current_datarate >= DR_4)
              && (current_channel_mask[4] & 0x00FF) == 0) {
          current_channel_mask[4] = channel_mask[4];
      }
  
      if (params->aggregate_timeoff <= _lora_time->get_elapsed_time(params->last_aggregate_tx_time)) {
          // Reset Aggregated time off
          *aggregate_timeOff = 0;
  
          // Update bands Time OFF
          next_tx_delay = update_band_timeoff(params->joined, params->dc_enabled, bands, US915_MAX_NB_BANDS);
  
          // Search how many channels are enabled
          nb_enabled_channels = enabled_channel_count(params->current_datarate,
                                                      current_channel_mask,
                                                      enabled_channels, &delay_tx);
      } else {
          delay_tx++;
          next_tx_delay = params->aggregate_timeoff - _lora_time->get_elapsed_time(params->last_aggregate_tx_time);
      }
  
      if (nb_enabled_channels > 0) {
          // We found a valid channel
          *channel = enabled_channels[get_random(0, nb_enabled_channels - 1)];
          // Disable the channel in the mask
          disable_channel(current_channel_mask, *channel, US915_MAX_NB_CHANNELS);
  
          *time = 0;
          return LORAWAN_STATUS_OK;
  
      } else {
  
          if (delay_tx > 0) {
              // Delay transmission due to AggregatedTimeOff or to a band time off
              *time = next_tx_delay;
              return LORAWAN_STATUS_DUTYCYCLE_RESTRICTED;
          }
  
          // Datarate not supported by any channel
          *time = 0;
          return LORAWAN_STATUS_NO_CHANNEL_FOUND;
      }
  }
  
  void LoRaPHYUS915::set_tx_cont_mode(cw_mode_params_t *params, uint32_t given_frequency)
  {
      (void)given_frequency;
  
      int8_t tx_power_limited = limit_tx_power(params->tx_power,
                                               bands[channels[params->channel].band].max_tx_pwr,
                                               params->datarate);
      int8_t phyTxPower = 0;
      uint32_t frequency = channels[params->channel].frequency;
  
      // Calculate physical TX power
      phyTxPower = compute_tx_power(tx_power_limited, US915_DEFAULT_MAX_ERP, 0);
  
      _radio->lock();
  
      _radio->set_tx_continuous_wave(frequency, phyTxPower, params->timeout);
  
      _radio->unlock();
  }
  
  uint8_t LoRaPHYUS915::apply_DR_offset(int8_t dr, int8_t dr_offset)
  {
      return datarate_offsets_US915[dr][dr_offset];
  }
  
  
  void LoRaPHYUS915::intersect_channel_mask(const uint16_t *source,
                                            uint16_t *destination, uint8_t size)
  {
      for (uint8_t i = 0; i < size; i++) {
          destination[i] &= source[i];
      }
  }
  
  void LoRaPHYUS915::fill_channel_mask_with_fsb(const uint16_t *expectation,
                                                const uint16_t *fsb_mask,
                                                uint16_t *destination,
                                                uint8_t size)
  {
      for (uint8_t i = 0; i < size; i++) {
          destination[i] = expectation[i] & fsb_mask[i];
      }
  
  }
  
  void LoRaPHYUS915::fill_channel_mask_with_value(uint16_t *channel_mask,
                                                  uint16_t value, uint8_t size)
  {
      for (uint8_t i = 0; i < size; i++) {
          channel_mask[i] = value;
      }
  }
  