uhd

//

// Copyright 2010-2011 Ettus Research LLC

//

// This program is free software: you can redistribute it and/or modify

// it under the terms of the GNU General Public License as published by

// the Free Software Foundation, either version 3 of the License, or

// (at your option) any later version.

//

// This program is distributed in the hope that it will be useful,

// but WITHOUT ANY WARRANTY; without even the implied warranty of

// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the

// GNU General Public License for more details.

//

// You should have received a copy of the GNU General Public License

// along with this program.  If not, see <http://www.gnu.org/licenses/>.

//

#include <uhd/property_tree.hpp>

#include <uhd/usrp/multi_usrp.hpp>

#include <uhd/usrp/mboard_iface.hpp>

#include <uhd/utils/msg.hpp>

#include <uhd/exception.hpp>

#include <uhd/utils/msg.hpp>

#include <uhd/utils/gain_group.hpp>

#include <boost/thread.hpp>

#include <boost/foreach.hpp>

#include <boost/format.hpp>

#include <cmath>

using namespace uhd;

using namespace uhd::usrp;

const std::string multi_usrp::ALL_GAINS = "";

/***********************************************************************

 * Helper methods

 **********************************************************************/

static void do_samp_rate_warning_message(

    double target_rate,

    double actual_rate,

    const std::string &xx

){

    static const double max_allowed_error = 1.0; //Sps

    if (std::abs(target_rate - actual_rate) > max_allowed_error){

        UHD_MSG(warning) << boost::format(

            "The hardware does not support the requested %s sample rate:\n"

            "Target sample rate: %f MSps\n"

            "Actual sample rate: %f MSps\n"

        ) % xx % (target_rate/1e6) % (actual_rate/1e6);

    }

}

static void do_tune_freq_warning_message(

    double target_freq,

    double actual_freq,

    const std::string &xx

){

    static const double max_allowed_error = 1.0; //Hz

    if (std::abs(target_freq - actual_freq) > max_allowed_error){

        UHD_MSG(warning) << boost::format(

            "The hardware does not support the requested %s frequency:\n"

            "Target frequency: %f MHz\n"

            "Actual frequency: %f MHz\n"

        ) % xx % (target_freq/1e6) % (actual_freq/1e6);

    }

}

static meta_range_t make_overall_tune_range(

    const meta_range_t &fe_range,

    const meta_range_t &dsp_range,

    const double bw

){

    return meta_range_t(

        fe_range.start() + std::max(dsp_range.start(), -bw),

        fe_range.stop() + std::min(dsp_range.stop(), bw),

        dsp_range.step()

    );

}

/***********************************************************************

 * Gain helper functions

 **********************************************************************/

static double get_gain_value(property_tree::sptr subtree){

    return subtree->access<double>("value").get();

}

static void set_gain_value(property_tree::sptr subtree, const double gain){

    subtree->access<double>("value").set(gain);

}

static meta_range_t get_gain_range(property_tree::sptr subtree){

    return subtree->access<meta_range_t>("range").get();

}

static gain_fcns_t make_gain_fcns_from_subtree(property_tree::sptr subtree){

    gain_fcns_t gain_fcns;

    gain_fcns.get_range = boost::bind(&get_gain_range, subtree);

    gain_fcns.get_value = boost::bind(&get_gain_value, subtree);

    gain_fcns.set_value = boost::bind(&set_gain_value, subtree, _1);

    return gain_fcns;

}

/***********************************************************************

 * Tune Helper Functions

 **********************************************************************/

static const double RX_SIGN = +1.0;

static const double TX_SIGN = -1.0;

static tune_result_t tune_xx_subdev_and_dsp(

    const double xx_sign,

    property_tree::sptr dsp_subtree,

    property_tree::sptr rf_fe_subtree,

    const tune_request_t &tune_request

){

    //------------------------------------------------------------------

    //-- calculate the LO offset, only used with automatic policy

    //------------------------------------------------------------------

    double lo_offset = 0.0;

    if (rf_fe_subtree->access<bool>("use_lo_offset").get()){

        //If the local oscillator will be in the passband, use an offset.

        //But constrain the LO offset by the width of the filter bandwidth.

        const double rate = dsp_subtree->access<double>("rate/value").get();

        const double bw = rf_fe_subtree->access<double>("bandwidth/value").get();

        if (bw > rate) lo_offset = std::min((bw - rate)/2, rate/2);

    }

    //------------------------------------------------------------------

    //-- set the RF frequency depending upon the policy

    //------------------------------------------------------------------

    double target_rf_freq = 0.0;

    switch (tune_request.rf_freq_policy){

    case tune_request_t::POLICY_AUTO:

        target_rf_freq = tune_request.target_freq + lo_offset;

        rf_fe_subtree->access<double>("freq/value").set(target_rf_freq);

        break;

    case tune_request_t::POLICY_MANUAL:

        target_rf_freq = tune_request.rf_freq;

        rf_fe_subtree->access<double>("freq/value").set(target_rf_freq);

        break;

    case tune_request_t::POLICY_NONE: break; //does not set

    }

    const double actual_rf_freq = rf_fe_subtree->access<double>("freq/value").get();

    //------------------------------------------------------------------

    //-- calculate the dsp freq, only used with automatic policy

    //------------------------------------------------------------------

    double target_dsp_freq = actual_rf_freq - tune_request.target_freq;

    //invert the sign on the dsp freq for transmit

    target_dsp_freq *= xx_sign;

    //------------------------------------------------------------------

    //-- set the dsp frequency depending upon the dsp frequency policy

    //------------------------------------------------------------------

    switch (tune_request.dsp_freq_policy){

    case tune_request_t::POLICY_AUTO:

        dsp_subtree->access<double>("freq/value").set(target_dsp_freq);

        break;

    case tune_request_t::POLICY_MANUAL:

        target_dsp_freq = tune_request.dsp_freq;

        dsp_subtree->access<double>("freq/value").set(target_dsp_freq);

        break;

    case tune_request_t::POLICY_NONE: break; //does not set

    }

    const double actual_dsp_freq = dsp_subtree->access<double>("freq/value").get();

    //------------------------------------------------------------------

    //-- load and return the tune result

    //------------------------------------------------------------------

    tune_result_t tune_result;

    tune_result.target_rf_freq = target_rf_freq;

    tune_result.actual_rf_freq = actual_rf_freq;

    tune_result.target_dsp_freq = target_dsp_freq;

    tune_result.actual_dsp_freq = actual_dsp_freq;

    return tune_result;

}

static double derive_freq_from_xx_subdev_and_dsp(

    const double xx_sign,

    property_tree::sptr dsp_subtree,

    property_tree::sptr rf_fe_subtree

){

    //extract actual dsp and IF frequencies

    const double actual_rf_freq = rf_fe_subtree->access<double>("freq/value").get();

    const double actual_dsp_freq = dsp_subtree->access<double>("freq/value").get();

    //invert the sign on the dsp freq for transmit

    return actual_rf_freq - actual_dsp_freq * xx_sign;

}

/***********************************************************************

 * Multi USRP Implementation

 **********************************************************************/

class multi_usrp_impl : public multi_usrp{

public:

    multi_usrp_impl(const device_addr_t &addr){

        _dev = device::make(addr);

        _tree = (*_dev)[0].as<property_tree::sptr>();

    }

    device::sptr get_device(void){

        return _dev;

    }

    /*******************************************************************

     * Mboard methods

     ******************************************************************/

    void set_master_clock_rate(double rate, size_t mboard){

        if (mboard != ALL_MBOARDS){

            _tree->access<double>(mb_root(mboard) / "tick_rate").set(rate);

            return;

        }

        for (size_t m = 0; m < get_num_mboards(); m++){

            set_master_clock_rate(rate, m);

        }

    }

    double get_master_clock_rate(size_t mboard){

        return _tree->access<double>(mb_root(mboard) / "tick_rate").get();

    }

    std::string get_pp_string(void){

        std::string buff = str(boost::format(

            "%s USRP:\n"

            "  Device: %s\n"

        )

            % ((get_num_mboards() > 1)? "Multi" : "Single")

            % (_tree->access<std::string>("/name").get())

        );

        for (size_t m = 0; m < get_num_mboards(); m++){

            buff += str(boost::format(

                "  Mboard %d: %s\n"

            ) % m

                % (_tree->access<std::string>(mb_root(m) / "name").get())

            );

        }

        //----------- rx side of life ----------------------------------

        for (size_t m = 0, chan = 0; m < get_num_mboards(); m++){

            for (; chan < (m + 1)*get_rx_subdev_spec(m).size(); chan++){

                buff += str(boost::format(

                    "  RX Channel: %u\n"

                    "    RX DSP: %s\n"

                    "    RX Dboard: %s\n"

                    "    RX Subdev: %s\n"

                ) % chan

                    % rx_dsp_root(chan).leaf()

                    % rx_rf_fe_root(chan).branch_path().branch_path().leaf()

                    % (_tree->access<std::string>(rx_rf_fe_root(chan) / "name").get())

                );

            }

        }

        //----------- tx side of life ----------------------------------

        for (size_t m = 0, chan = 0; m < get_num_mboards(); m++){

            for (; chan < (m + 1)*get_tx_subdev_spec(m).size(); chan++){

                buff += str(boost::format(

                    "  TX Channel: %u\n"

                    "    TX DSP: %s\n"

                    "    TX Dboard: %s\n"

                    "    TX Subdev: %s\n"

                ) % chan

                    % tx_dsp_root(chan).leaf()

                    % tx_rf_fe_root(chan).branch_path().branch_path().leaf()

                    % (_tree->access<std::string>(tx_rf_fe_root(chan) / "name").get())

                );

            }

        }

        return buff;

    }

    std::string get_mboard_name(size_t mboard){

        return _tree->access<std::string>(mb_root(mboard) / "name").get();

    }

    time_spec_t get_time_now(size_t mboard = 0){

        return _tree->access<time_spec_t>(mb_root(mboard) / "time/now").get();

    }

    time_spec_t get_time_last_pps(size_t mboard = 0){

        return _tree->access<time_spec_t>(mb_root(mboard) / "time/pps").get();

    }

    void set_time_now(const time_spec_t &time_spec, size_t mboard){

        if (mboard != ALL_MBOARDS){

            _tree->access<time_spec_t>(mb_root(mboard) / "time/now").set(time_spec);

            return;

        }

        for (size_t m = 0; m < get_num_mboards(); m++){

            set_time_now(time_spec, m);

        }

    }

    void set_time_next_pps(const time_spec_t &time_spec){

        for (size_t m = 0; m < get_num_mboards(); m++){

            _tree->access<time_spec_t>(mb_root(m) / "time/pps").set(time_spec);

        }

    }

    void set_time_unknown_pps(const time_spec_t &time_spec){

        UHD_MSG(status) << "    1) catch time transition at pps edge" << std::endl;

        time_spec_t time_start = get_time_now();

        time_spec_t time_start_last_pps = get_time_last_pps();

        while(true){

            if (get_time_last_pps() != time_start_last_pps) break;

            if ((get_time_now() - time_start) > time_spec_t(1.1)){

                throw uhd::runtime_error(

                    "Board 0 may not be getting a PPS signal!\n"

                    "No PPS detected within the time interval.\n"

                    "See the application notes for your device.\n"

                );

            }

        }

        UHD_MSG(status) << "    2) set times next pps (synchronously)" << std::endl;

        set_time_next_pps(time_spec);

        boost::this_thread::sleep(boost::posix_time::seconds(1));

        //verify that the time registers are read to be within a few RTT

        for (size_t m = 1; m < get_num_mboards(); m++){

            time_spec_t time_0 = this->get_time_now(0);

            time_spec_t time_i = this->get_time_now(m);

            if (time_i < time_0 or (time_i - time_0) > time_spec_t(0.01)){ //10 ms: greater than RTT but not too big

                UHD_MSG(warning) << boost::format(

                    "Detected time deviation between board %d and board 0.\n"

                    "Board 0 time is %f seconds.\n"

                    "Board %d time is %f seconds.\n"

                ) % m % time_0.get_real_secs() % m % time_i.get_real_secs();

            }

        }

    }

    bool get_time_synchronized(void){

        for (size_t m = 1; m < get_num_mboards(); m++){

            time_spec_t time_0 = this->get_time_now(0);

            time_spec_t time_i = this->get_time_now(m);

            if (time_i < time_0 or (time_i - time_0) > time_spec_t(0.01)) return false;

        }

        return true;

    }

    void issue_stream_cmd(const stream_cmd_t &stream_cmd, size_t chan){

        if (chan != ALL_CHANS){

            _tree->access<stream_cmd_t>(rx_dsp_root(chan) / "stream_cmd").set(stream_cmd);

            return;

        }

        for (size_t c = 0; c < get_rx_num_channels(); c++){

            issue_stream_cmd(stream_cmd, c);

        }

    }

    void set_clock_config(const clock_config_t &clock_config, size_t mboard){

        if (mboard != ALL_MBOARDS){

            //set the reference source...

            std::string clock_source;

            switch(clock_config.ref_source){

            case clock_config_t::REF_INT: clock_source = "internal"; break;

            case clock_config_t::PPS_SMA: clock_source = "external"; break;

            case clock_config_t::PPS_MIMO: clock_source = "mimo"; break;

            default: clock_source = "unknown";

            }

            if (clock_source == "external" and clock_config.pps_polarity == clock_config_t::PPS_NEG) clock_source = "_external_";

            _tree->access<std::string>(mb_root(mboard) / "clock_source" / "value").set(clock_source);

            //set the time source

            std::string time_source;

            switch(clock_config.pps_source){

            case clock_config_t::PPS_INT: time_source = "internal"; break;

            case clock_config_t::PPS_SMA: time_source = "external"; break;

            case clock_config_t::PPS_MIMO: time_source = "mimo"; break;

            default: time_source = "unknown";

            }

            _tree->access<std::string>(mb_root(mboard) / "time_source" / "value").set(time_source);

            return;

        }

        for (size_t m = 0; m < get_num_mboards(); m++){

            set_clock_config(clock_config, m);

        }

    }

    size_t get_num_mboards(void){

        return _tree->list("/mboards").size();

    }

    sensor_value_t get_mboard_sensor(const std::string &name, size_t mboard){

        return _tree->access<sensor_value_t>(mb_root(mboard) / "sensors" / name).get();

    }

    std::vector<std::string> get_mboard_sensor_names(size_t mboard){

        return _tree->list(mb_root(mboard) / "sensors");

    }

    mboard_iface::sptr get_mboard_iface(size_t){

        return mboard_iface::sptr(); //not implemented

    }

    /*******************************************************************

     * RX methods

     ******************************************************************/

    void set_rx_subdev_spec(const subdev_spec_t &spec, size_t mboard){

        if (mboard != ALL_MBOARDS){

            _tree->access<subdev_spec_t>(mb_root(mboard) / "rx_subdev_spec").set(spec);

            return;

        }

        for (size_t m = 0; m < get_num_mboards(); m++){

            set_rx_subdev_spec(spec, m);

        }

    }

    subdev_spec_t get_rx_subdev_spec(size_t mboard){

        return _tree->access<subdev_spec_t>(mb_root(mboard) / "rx_subdev_spec").get();

    }

    size_t get_rx_num_channels(void){

        size_t sum = 0;

        for (size_t m = 0; m < get_num_mboards(); m++){

            sum += get_rx_subdev_spec(m).size();

        }

        return sum;

    }

    std::string get_rx_subdev_name(size_t chan){

        return _tree->access<std::string>(rx_rf_fe_root(chan) / "name").get();

    }

    void set_rx_rate(double rate, size_t chan){

        if (chan != ALL_CHANS){

            _tree->access<double>(rx_dsp_root(chan) / "rate" / "value").set(rate);

            do_samp_rate_warning_message(rate, get_rx_rate(chan), "RX");

            return;

        }

        for (size_t c = 0; c < get_rx_num_channels(); c++){

            set_rx_rate(rate, c);

        }

    }

    double get_rx_rate(size_t chan){

        return _tree->access<double>(rx_dsp_root(chan) / "rate" / "value").get();

    }

    tune_result_t set_rx_freq(const tune_request_t &tune_request, size_t chan){

        tune_result_t r = tune_xx_subdev_and_dsp(RX_SIGN, _tree->subtree(rx_dsp_root(chan)), _tree->subtree(rx_rf_fe_root(chan)), tune_request);

        do_tune_freq_warning_message(tune_request.target_freq, get_rx_freq(chan), "RX");

        return r;

    }

    double get_rx_freq(size_t chan){

        return derive_freq_from_xx_subdev_and_dsp(RX_SIGN, _tree->subtree(rx_dsp_root(chan)), _tree->subtree(rx_rf_fe_root(chan)));

    }

    freq_range_t get_rx_freq_range(size_t chan){

        return make_overall_tune_range(

            _tree->access<meta_range_t>(rx_rf_fe_root(chan) / "freq" / "range").get(),

            _tree->access<meta_range_t>(rx_dsp_root(chan) / "freq" / "range").get(),

            this->get_rx_bandwidth(chan)

        );

    }

    void set_rx_gain(double gain, const std::string &name, size_t chan){

        return rx_gain_group(chan)->set_value(gain, name);

    }

    double get_rx_gain(const std::string &name, size_t chan){

        return rx_gain_group(chan)->get_value(name);

    }

    gain_range_t get_rx_gain_range(const std::string &name, size_t chan){

        return rx_gain_group(chan)->get_range(name);

    }

    std::vector<std::string> get_rx_gain_names(size_t chan){

        return rx_gain_group(chan)->get_names();

    }

    void set_rx_antenna(const std::string &ant, size_t chan){

        _tree->access<std::string>(rx_rf_fe_root(chan) / "antenna" / "value").set(ant);

    }

    std::string get_rx_antenna(size_t chan){

        return _tree->access<std::string>(rx_rf_fe_root(chan) / "antenna" / "value").get();

    }

    std::vector<std::string> get_rx_antennas(size_t chan){

        return _tree->access<std::vector<std::string> >(rx_rf_fe_root(chan) / "antenna" / "options").get();

    }

    void set_rx_bandwidth(double bandwidth, size_t chan){

        _tree->access<double>(rx_rf_fe_root(chan) / "bandwidth" / "value").set(bandwidth);

    }

    double get_rx_bandwidth(size_t chan){

        return _tree->access<double>(rx_rf_fe_root(chan) / "bandwidth" / "value").get();

    }

    dboard_iface::sptr get_rx_dboard_iface(size_t chan){

        return _tree->access<dboard_iface::sptr>(rx_rf_fe_root(chan).branch_path().branch_path() / "iface").get();

    }

    sensor_value_t get_rx_sensor(const std::string &name, size_t chan){

        return _tree->access<sensor_value_t>(rx_rf_fe_root(chan) / "sensors" / name).get();

    }

    std::vector<std::string> get_rx_sensor_names(size_t chan){

        return _tree->list(rx_rf_fe_root(chan) / "sensors");

    }

    /*******************************************************************

     * TX methods

     ******************************************************************/

    void set_tx_subdev_spec(const subdev_spec_t &spec, size_t mboard){

        if (mboard != ALL_MBOARDS){

            _tree->access<subdev_spec_t>(mb_root(mboard) / "tx_subdev_spec").set(spec);

            return;

        }

        for (size_t m = 0; m < get_num_mboards(); m++){

            set_tx_subdev_spec(spec, m);

        }

    }

    subdev_spec_t get_tx_subdev_spec(size_t mboard){

        return _tree->access<subdev_spec_t>(mb_root(mboard) / "tx_subdev_spec").get();

    }

    std::string get_tx_subdev_name(size_t chan){

        return _tree->access<std::string>(tx_rf_fe_root(chan) / "name").get();

    }

    size_t get_tx_num_channels(void){

        size_t sum = 0;

        for (size_t m = 0; m < get_num_mboards(); m++){

            sum += get_tx_subdev_spec(m).size();

        }

        return sum;

    }

    void set_tx_rate(double rate, size_t chan){

        if (chan != ALL_CHANS){

            _tree->access<double>(tx_dsp_root(chan) / "rate" / "value").set(rate);

            do_samp_rate_warning_message(rate, get_tx_rate(chan), "TX");

            return;

        }

        for (size_t c = 0; c < get_tx_num_channels(); c++){

            set_tx_rate(rate, c);

        }

    }

    double get_tx_rate(size_t chan){

        return _tree->access<double>(tx_dsp_root(chan) / "rate" / "value").get();

    }

    tune_result_t set_tx_freq(const tune_request_t &tune_request, size_t chan){

        tune_result_t r = tune_xx_subdev_and_dsp(TX_SIGN, _tree->subtree(tx_dsp_root(chan)), _tree->subtree(tx_rf_fe_root(chan)), tune_request);

        do_tune_freq_warning_message(tune_request.target_freq, get_tx_freq(chan), "TX");

        return r;

    }

    double get_tx_freq(size_t chan){

        return derive_freq_from_xx_subdev_and_dsp(TX_SIGN, _tree->subtree(tx_dsp_root(chan)), _tree->subtree(tx_rf_fe_root(chan)));

    }

    freq_range_t get_tx_freq_range(size_t chan){

        return make_overall_tune_range(

            _tree->access<meta_range_t>(tx_rf_fe_root(chan) / "freq" / "range").get(),

            _tree->access<meta_range_t>(tx_dsp_root(chan) / "freq" / "range").get(),

            this->get_tx_bandwidth(chan)

        );

    }

    void set_tx_gain(double gain, const std::string &name, size_t chan){

        return tx_gain_group(chan)->set_value(gain, name);

    }

    double get_tx_gain(const std::string &name, size_t chan){

        return tx_gain_group(chan)->get_value(name);

    }

    gain_range_t get_tx_gain_range(const std::string &name, size_t chan){

        return tx_gain_group(chan)->get_range(name);

    }

    std::vector<std::string> get_tx_gain_names(size_t chan){

        return tx_gain_group(chan)->get_names();

    }

    void set_tx_antenna(const std::string &ant, size_t chan){

        _tree->access<std::string>(tx_rf_fe_root(chan) / "antenna" / "value").set(ant);

    }

    std::string get_tx_antenna(size_t chan){

        return _tree->access<std::string>(tx_rf_fe_root(chan) / "antenna" / "value").get();

    }

    std::vector<std::string> get_tx_antennas(size_t chan){

        return _tree->access<std::vector<std::string> >(tx_rf_fe_root(chan) / "antenna" / "options").get();

    }

    void set_tx_bandwidth(double bandwidth, size_t chan){

        _tree->access<double>(tx_rf_fe_root(chan) / "bandwidth" / "value").set(bandwidth);

    }

    double get_tx_bandwidth(size_t chan){

        return _tree->access<double>(tx_rf_fe_root(chan) / "bandwidth" / "value").get();

    }

    dboard_iface::sptr get_tx_dboard_iface(size_t chan){

        return _tree->access<dboard_iface::sptr>(tx_rf_fe_root(chan).branch_path().branch_path() / "iface").get();

    }

    sensor_value_t get_tx_sensor(const std::string &name, size_t chan){

        return _tree->access<sensor_value_t>(tx_rf_fe_root(chan) / "sensors" / name).get();

    }

    std::vector<std::string> get_tx_sensor_names(size_t chan){

        return _tree->list(tx_rf_fe_root(chan) / "sensors");

    }

private:

    device::sptr _dev;

    property_tree::sptr _tree;

    struct mboard_chan_pair{

        size_t mboard, chan;

        mboard_chan_pair(void): mboard(0), chan(0){}

    };

    mboard_chan_pair rx_chan_to_mcp(size_t chan){

        mboard_chan_pair mcp;

        mcp.chan = chan;

        for (mcp.mboard = 0; mcp.mboard < get_num_mboards(); mcp.mboard++){

            size_t sss = get_rx_subdev_spec(mcp.mboard).size();

            if (mcp.chan < sss) break;

            mcp.chan -= sss;

        }

        return mcp;

    }

    mboard_chan_pair tx_chan_to_mcp(size_t chan){

        mboard_chan_pair mcp;

        mcp.chan = chan;

        for (mcp.mboard = 0; mcp.mboard < get_num_mboards(); mcp.mboard++){

            size_t sss = get_tx_subdev_spec(mcp.mboard).size();

            if (mcp.chan < sss) break;

            mcp.chan -= sss;

        }

        return mcp;

    }

    fs_path mb_root(const size_t mboard){

        const std::string name = _tree->list("/mboards").at(mboard);

        return "/mboards/" + name;

    }

    fs_path rx_dsp_root(const size_t chan){

        mboard_chan_pair mcp = rx_chan_to_mcp(chan);

        const std::string name = _tree->list(mb_root(mcp.mboard) / "rx_dsps").at(mcp.chan);

        return mb_root(mcp.mboard) / "rx_dsps" / name;

    }

    fs_path tx_dsp_root(const size_t chan){

        mboard_chan_pair mcp = tx_chan_to_mcp(chan);

        const std::string name = _tree->list(mb_root(mcp.mboard) / "tx_dsps").at(mcp.chan);

        return mb_root(mcp.mboard) / "tx_dsps" / name;

    }

    fs_path rx_rf_fe_root(const size_t chan){

        mboard_chan_pair mcp = rx_chan_to_mcp(chan);

        const subdev_spec_pair_t spec = get_rx_subdev_spec(mcp.mboard).at(mcp.chan);

        return mb_root(mcp.mboard) / "dboards" / spec.db_name / "rx_frontends" / spec.sd_name;

    }

    fs_path tx_rf_fe_root(const size_t chan){

        mboard_chan_pair mcp = tx_chan_to_mcp(chan);

        const subdev_spec_pair_t spec = get_tx_subdev_spec(mcp.mboard).at(mcp.chan);

        return mb_root(mcp.mboard) / "dboards" / spec.db_name / "tx_frontends" / spec.sd_name;

    }

    gain_group::sptr rx_gain_group(size_t chan){

        mboard_chan_pair mcp = rx_chan_to_mcp(chan);

        const subdev_spec_pair_t spec = get_rx_subdev_spec(mcp.mboard).at(mcp.chan);

        gain_group::sptr gg = gain_group::make();

        BOOST_FOREACH(const std::string &name, _tree->list(mb_root(mcp.mboard) / "rx_codecs" / spec.db_name / "gains")){

            gg->register_fcns("ADC-"+name, make_gain_fcns_from_subtree(_tree->subtree(mb_root(mcp.mboard) / "rx_codecs" / spec.db_name / "gains" / name)), 0 /* low prio */);

        }

        BOOST_FOREACH(const std::string &name, _tree->list(rx_rf_fe_root(chan) / "gains")){

            gg->register_fcns(name, make_gain_fcns_from_subtree(_tree->subtree(rx_rf_fe_root(chan) / "gains" / name)), 1 /* high prio */);

        }

        return gg;

    }

    gain_group::sptr tx_gain_group(size_t chan){

        mboard_chan_pair mcp = tx_chan_to_mcp(chan);

        const subdev_spec_pair_t spec = get_tx_subdev_spec(mcp.mboard).at(mcp.chan);

        gain_group::sptr gg = gain_group::make();

        BOOST_FOREACH(const std::string &name, _tree->list(mb_root(mcp.mboard) / "tx_codecs" / spec.db_name / "gains")){

            gg->register_fcns("ADC-"+name, make_gain_fcns_from_subtree(_tree->subtree(mb_root(mcp.mboard) / "tx_codecs" / spec.db_name / "gains" / name)), 1 /* high prio */);

        }

        BOOST_FOREACH(const std::string &name, _tree->list(tx_rf_fe_root(chan) / "gains")){

            gg->register_fcns(name, make_gain_fcns_from_subtree(_tree->subtree(tx_rf_fe_root(chan) / "gains" / name)), 0 /* low prio */);

        }

        return gg;

    }

};

/***********************************************************************

 * The Make Function

 **********************************************************************/

multi_usrp::sptr multi_usrp::make(const device_addr_t &dev_addr){

    return sptr(new multi_usrp_impl(dev_addr));

}