path: root/host/lib/include/uhdlib/usrp/common/adf435x.hpp

//
// Copyright 2015 Ettus Research LLC
// Copyright 2018 Ettus Research, a National Instruments Company
//
// SPDX-License-Identifier: GPL-3.0-or-later
//

#ifndef INCLUDED_ADF435X_HPP
#define INCLUDED_ADF435X_HPP

#include "adf4350_regs.hpp"
#include "adf4351_regs.hpp"
#include <uhd/exception.hpp>
#include <uhd/types/dict.hpp>
#include <uhd/types/ranges.hpp>
#include <uhd/utils/log.hpp>
#include <uhdlib/utils/math.hpp>
#include <boost/function.hpp>
#include <boost/math/special_functions/round.hpp>
#include <boost/thread.hpp>
#include <vector>

class adf435x_iface
{
public:
    typedef boost::shared_ptr<adf435x_iface> sptr;
    typedef boost::function<void(std::vector<uint32_t>)> write_fn_t;

    static sptr make_adf4350(write_fn_t write);
    static sptr make_adf4351(write_fn_t write);

    virtual ~adf435x_iface() = 0;

    enum output_t { RF_OUTPUT_A, RF_OUTPUT_B };

    enum prescaler_t { PRESCALER_4_5, PRESCALER_8_9 };

    enum feedback_sel_t { FB_SEL_FUNDAMENTAL, FB_SEL_DIVIDED };

    enum output_power_t {
        OUTPUT_POWER_M4DBM,
        OUTPUT_POWER_M1DBM,
        OUTPUT_POWER_2DBM,
        OUTPUT_POWER_5DBM
    };

    enum muxout_t {
        MUXOUT_3STATE,
        MUXOUT_DVDD,
        MUXOUT_DGND,
        MUXOUT_RDIV,
        MUXOUT_NDIV,
        MUXOUT_ALD,
        MUXOUT_DLD
    };

    enum tuning_mode_t { TUNING_MODE_HIGH_RESOLUTION, TUNING_MODE_LOW_SPUR };

    /**
     * Charge Pump Currents
     */
    enum charge_pump_current_t {
        CHARGE_PUMP_CURRENT_0_31MA = 0,
        CHARGE_PUMP_CURRENT_0_63MA = 1,
        CHARGE_PUMP_CURRENT_0_94MA = 2,
        CHARGE_PUMP_CURRENT_1_25MA = 3,
        CHARGE_PUMP_CURRENT_1_56MA = 4,
        CHARGE_PUMP_CURRENT_1_88MA = 5,
        CHARGE_PUMP_CURRENT_2_19MA = 6,
        CHARGE_PUMP_CURRENT_2_50MA = 7,
        CHARGE_PUMP_CURRENT_2_81MA = 8,
        CHARGE_PUMP_CURRENT_3_13MA = 9,
        CHARGE_PUMP_CURRENT_3_44MA = 10,
        CHARGE_PUMP_CURRENT_3_75MA = 11,
        CHARGE_PUMP_CURRENT_4_07MA = 12,
        CHARGE_PUMP_CURRENT_4_38MA = 13,
        CHARGE_PUMP_CURRENT_4_69MA = 14,
        CHARGE_PUMP_CURRENT_5_00MA = 15
    };


    virtual void set_reference_freq(double fref) = 0;

    virtual void set_prescaler(prescaler_t prescaler) = 0;

    virtual void set_feedback_select(feedback_sel_t fb_sel) = 0;

    virtual void set_output_power(output_t output, output_power_t power) = 0;

    void set_output_power(output_power_t power)
    {
        set_output_power(RF_OUTPUT_A, power);
    }

    virtual void set_output_enable(output_t output, bool enable) = 0;

    virtual void set_muxout_mode(muxout_t mode) = 0;

    //! Sets the tuning mode for subsequent tunes
    /**
     * High resolution mode will use the maximum modulus value to ensure an
     * exact tune whenever possible. Low spur mode will try to find the "best"
     * modulus for spur performance, which may result in loss of precision.
     *
     * To fully utilize low spur mode, the charge pump current should be
     * decreased.  This will vary based on board design. For example, for
     * TwinRX LO2, the current is decreased from 1.88 mA to 1.25 mA. In
     * addition, the 8/9 prescaler should be used instead of 4/5 whenever
     * possible.
     */
    virtual void set_tuning_mode(tuning_mode_t mode) = 0;

    virtual void set_charge_pump_current(charge_pump_current_t cp_current) = 0;

    virtual double set_charge_pump_current(double current, bool flush = false) = 0;

    virtual uhd::meta_range_t get_charge_pump_current_range() = 0;

    virtual uhd::range_t get_int_range() = 0;

    virtual double set_frequency(
        double target_freq, bool int_n_mode, bool flush = false) = 0;

    virtual void commit(void) = 0;
};

template <typename adf435x_regs_t>
class adf435x_impl : public adf435x_iface
{
public:
    adf435x_impl(write_fn_t write_fn)
        : _write_fn(write_fn)
        , _regs()
        , _fb_after_divider(false)
        , _reference_freq(0.0)
        , _N_min(-1)
    {
    }

    virtual ~adf435x_impl(){};

    void set_reference_freq(double fref)
    {
        _reference_freq = fref;
    }

    void set_feedback_select(feedback_sel_t fb_sel)
    {
        _fb_after_divider = (fb_sel == FB_SEL_DIVIDED);
    }

    void set_prescaler(prescaler_t prescaler)
    {
        if (prescaler == PRESCALER_8_9) {
            _regs.prescaler = adf435x_regs_t::PRESCALER_8_9;
            _N_min          = 75;
        } else {
            _regs.prescaler = adf435x_regs_t::PRESCALER_4_5;
            _N_min          = 23;
        }
    }

    void set_output_power(output_t output, output_power_t power)
    {
        switch (output) {
            case RF_OUTPUT_A:
                switch (power) {
                    case OUTPUT_POWER_M4DBM:
                        _regs.output_power = adf435x_regs_t::OUTPUT_POWER_M4DBM;
                        break;
                    case OUTPUT_POWER_M1DBM:
                        _regs.output_power = adf435x_regs_t::OUTPUT_POWER_M1DBM;
                        break;
                    case OUTPUT_POWER_2DBM:
                        _regs.output_power = adf435x_regs_t::OUTPUT_POWER_2DBM;
                        break;
                    case OUTPUT_POWER_5DBM:
                        _regs.output_power = adf435x_regs_t::OUTPUT_POWER_5DBM;
                        break;
                    default:
                        UHD_THROW_INVALID_CODE_PATH();
                }
                break;
            case RF_OUTPUT_B:
                switch (power) {
                    case OUTPUT_POWER_M4DBM:
                        _regs.aux_output_power = adf435x_regs_t::AUX_OUTPUT_POWER_M4DBM;
                        break;
                    case OUTPUT_POWER_M1DBM:
                        _regs.aux_output_power = adf435x_regs_t::AUX_OUTPUT_POWER_M1DBM;
                        break;
                    case OUTPUT_POWER_2DBM:
                        _regs.aux_output_power = adf435x_regs_t::AUX_OUTPUT_POWER_2DBM;
                        break;
                    case OUTPUT_POWER_5DBM:
                        _regs.aux_output_power = adf435x_regs_t::AUX_OUTPUT_POWER_5DBM;
                        break;
                    default:
                        UHD_THROW_INVALID_CODE_PATH();
                }
                break;
            default:
                UHD_THROW_INVALID_CODE_PATH();
        }
    }

    void set_output_enable(output_t output, bool enable)
    {
        switch (output) {
            case RF_OUTPUT_A:
                _regs.rf_output_enable = enable
                                             ? adf435x_regs_t::RF_OUTPUT_ENABLE_ENABLED
                                             : adf435x_regs_t::RF_OUTPUT_ENABLE_DISABLED;
                break;
            case RF_OUTPUT_B:
                _regs.aux_output_enable =
                    enable ? adf435x_regs_t::AUX_OUTPUT_ENABLE_ENABLED
                           : adf435x_regs_t::AUX_OUTPUT_ENABLE_DISABLED;
                break;
        }
    }

    void set_muxout_mode(muxout_t mode)
    {
        switch (mode) {
            case MUXOUT_3STATE:
                _regs.muxout = adf435x_regs_t::MUXOUT_3STATE;
                break;
            case MUXOUT_DVDD:
                _regs.muxout = adf435x_regs_t::MUXOUT_DVDD;
                break;
            case MUXOUT_DGND:
                _regs.muxout = adf435x_regs_t::MUXOUT_DGND;
                break;
            case MUXOUT_RDIV:
                _regs.muxout = adf435x_regs_t::MUXOUT_RDIV;
                break;
            case MUXOUT_NDIV:
                _regs.muxout = adf435x_regs_t::MUXOUT_NDIV;
                break;
            case MUXOUT_ALD:
                _regs.muxout = adf435x_regs_t::MUXOUT_ANALOG_LD;
                break;
            case MUXOUT_DLD:
                _regs.muxout = adf435x_regs_t::MUXOUT_DLD;
                break;
            default:
                UHD_THROW_INVALID_CODE_PATH();
        }
    }

    void set_tuning_mode(tuning_mode_t mode)
    {
        // New mode applies to subsequent tunes i.e. do not re-tune now
        _tuning_mode = mode;

        _regs.low_noise_and_spur = (_tuning_mode == TUNING_MODE_HIGH_RESOLUTION)
                                       ? adf435x_regs_t::LOW_NOISE_AND_SPUR_LOW_SPUR
                                       : adf435x_regs_t::LOW_NOISE_AND_SPUR_LOW_NOISE;
        _regs.phase_12_bit = (_tuning_mode == TUNING_MODE_HIGH_RESOLUTION) ? 0 : 1;
    }

    void set_charge_pump_current(charge_pump_current_t cp_current)
    {
        switch (cp_current) {
            case CHARGE_PUMP_CURRENT_0_31MA:
                _regs.charge_pump_current = adf435x_regs_t::CHARGE_PUMP_CURRENT_0_31MA;
                break;
            case CHARGE_PUMP_CURRENT_0_63MA:
                _regs.charge_pump_current = adf435x_regs_t::CHARGE_PUMP_CURRENT_0_63MA;
                break;
            case CHARGE_PUMP_CURRENT_0_94MA:
                _regs.charge_pump_current = adf435x_regs_t::CHARGE_PUMP_CURRENT_0_94MA;
                break;
            case CHARGE_PUMP_CURRENT_1_25MA:
                _regs.charge_pump_current = adf435x_regs_t::CHARGE_PUMP_CURRENT_1_25MA;
                break;
            case CHARGE_PUMP_CURRENT_1_56MA:
                _regs.charge_pump_current = adf435x_regs_t::CHARGE_PUMP_CURRENT_1_56MA;
                break;
            case CHARGE_PUMP_CURRENT_1_88MA:
                _regs.charge_pump_current = adf435x_regs_t::CHARGE_PUMP_CURRENT_1_88MA;
                break;
            case CHARGE_PUMP_CURRENT_2_19MA:
                _regs.charge_pump_current = adf435x_regs_t::CHARGE_PUMP_CURRENT_2_19MA;
                break;
            case CHARGE_PUMP_CURRENT_2_50MA:
                _regs.charge_pump_current = adf435x_regs_t::CHARGE_PUMP_CURRENT_2_50MA;
                break;
            case CHARGE_PUMP_CURRENT_2_81MA:
                _regs.charge_pump_current = adf435x_regs_t::CHARGE_PUMP_CURRENT_2_81MA;
                break;
            case CHARGE_PUMP_CURRENT_3_13MA:
                _regs.charge_pump_current = adf435x_regs_t::CHARGE_PUMP_CURRENT_3_13MA;
                break;
            case CHARGE_PUMP_CURRENT_3_44MA:
                _regs.charge_pump_current = adf435x_regs_t::CHARGE_PUMP_CURRENT_3_44MA;
                break;
            case CHARGE_PUMP_CURRENT_3_75MA:
                _regs.charge_pump_current = adf435x_regs_t::CHARGE_PUMP_CURRENT_3_75MA;
                break;
            case CHARGE_PUMP_CURRENT_4_07MA:
                _regs.charge_pump_current = adf435x_regs_t::CHARGE_PUMP_CURRENT_4_07MA;
                break;
            case CHARGE_PUMP_CURRENT_4_38MA:
                _regs.charge_pump_current = adf435x_regs_t::CHARGE_PUMP_CURRENT_4_38MA;
                break;
            case CHARGE_PUMP_CURRENT_4_69MA:
                _regs.charge_pump_current = adf435x_regs_t::CHARGE_PUMP_CURRENT_4_69MA;
                break;
            case CHARGE_PUMP_CURRENT_5_00MA:
                _regs.charge_pump_current = adf435x_regs_t::CHARGE_PUMP_CURRENT_5_00MA;
                break;
            default:
                UHD_THROW_INVALID_CODE_PATH();
        }
    }

    double set_charge_pump_current(const double current, const bool flush)
    {
        const auto cp_range = get_charge_pump_current_range();

        const auto coerced_current = cp_range.clip(current, true);
        const int current_step     = std::round((coerced_current / cp_range.step()) - 1);

        UHD_ASSERT_THROW(current_step >= 0 and current_step < 16);
        set_charge_pump_current(
            static_cast<adf435x_iface::charge_pump_current_t>(current_step));

        if (flush) {
            commit();
        }

        if (std::abs(current - coerced_current) > 0.01e-6) {
            UHD_LOG_WARNING("ADF435x",
                "Requested charge pump current was coerced! Requested: "
                    << std::setw(4) << current << " A  Actual: " << coerced_current
                    << " A");
        }

        return coerced_current;
    }

    uhd::meta_range_t get_charge_pump_current_range()
    {
        return uhd::meta_range_t(.3125e-6, 5e-6, .3125e-6);
    }

    uhd::range_t get_int_range()
    {
        if (_N_min < 0)
            throw uhd::runtime_error("set_prescaler must be called before get_int_range");
        return uhd::range_t(_N_min, 4095);
    }

    double set_frequency(double target_freq, bool int_n_mode, bool flush = false)
    {
        static const double REF_DOUBLER_THRESH_FREQ = 12.5e6;
        static const double PFD_FREQ_MAX            = 25.0e6;
        static const double BAND_SEL_FREQ_MAX       = 100e3;
        static const double VCO_FREQ_MIN            = 2.2e9;
        static const double VCO_FREQ_MAX            = 4.4e9;

        // Default invalid value for actual_freq
        double actual_freq = 0;

        uhd::range_t rf_divider_range = _get_rfdiv_range();
        uhd::range_t int_range        = get_int_range();

        double pfd_freq = 0;
        uint16_t R = 0, BS = 0, N = 0, FRAC = 0, MOD = 0;
        uint16_t RFdiv = static_cast<uint16_t>(rf_divider_range.start());
        bool D = false, T = false;

        // Reference doubler for 50% duty cycle
        D = (_reference_freq <= REF_DOUBLER_THRESH_FREQ);

        // increase RF divider until acceptable VCO frequency
        double vco_freq = target_freq;
        while (vco_freq < VCO_FREQ_MIN
               && RFdiv < static_cast<uint16_t>(rf_divider_range.stop())) {
            vco_freq *= 2;
            RFdiv *= 2;
        }

        /*
         * The goal here is to loop though possible R dividers,
         * band select clock dividers, N (int) dividers, and FRAC
         * (frac) dividers.
         *
         * Calculate the N and F dividers for each set of values.
         * The loop exits when it meets all of the constraints.
         * The resulting loop values are loaded into the registers.
         *
         * from pg.21
         *
         * f_pfd = f_ref*(1+D)/(R*(1+T))
         * f_vco = (N + (FRAC/MOD))*f_pfd
         *    N = f_vco/f_pfd - FRAC/MOD = f_vco*((R*(T+1))/(f_ref*(1+D))) - FRAC/MOD
         * f_actual = f_vco/RFdiv)
         */
        double feedback_freq = _fb_after_divider ? target_freq : vco_freq;

        for (R = 1; R <= 1023; R += 1) {
            // PFD input frequency = f_ref/R ... ignoring Reference doubler/divide-by-2 (D
            // & T)
            pfd_freq = _reference_freq * (D ? 2 : 1) / (R * (T ? 2 : 1));

            // keep the PFD frequency at or below 25MHz (Loop Filter Bandwidth)
            if (pfd_freq > PFD_FREQ_MAX)
                continue;

            // First, ignore fractional part of tuning
            N = uint16_t(std::floor(feedback_freq / pfd_freq));

            // keep N > minimum int divider requirement
            if (N < static_cast<uint16_t>(int_range.start()))
                continue;

            for (BS = 1; BS <= 255; BS += 1) {
                // keep the band select frequency at or below band_sel_freq_max
                // constraint on band select clock
                if (pfd_freq / BS > BAND_SEL_FREQ_MAX)
                    continue;
                goto done_loop;
            }
        }
    done_loop:

        double frac_part = (feedback_freq / pfd_freq) - N;
        if (int_n_mode) {
            if (frac_part >= 0.5) {
                // Round integer such that actual freq is closest to target
                N++;
            }
            FRAC = 0;
            MOD  = 2;
        } else if (_tuning_mode == TUNING_MODE_LOW_SPUR) {
            std::tie(FRAC, MOD) =
                uhd::math::rational_approximation(frac_part, 4095, 0.0001);
            if (MOD < 2) {
                FRAC *= 2;
                MOD *= 2;
            }
        } else {
            MOD  = 4095; // max fractional accuracy
            FRAC = static_cast<uint16_t>(std::round(frac_part * MOD));
        }

        // Reference divide-by-2 for 50% duty cycle
        // if R even, move one divide by 2 to to regs.reference_divide_by_2
        if (R % 2 == 0) {
            T = true;
            R /= 2;
        }

        // Typical phase resync time documented in data sheet pg.24
        static const double PHASE_RESYNC_TIME = 400e-6;

        // If feedback after divider, then compensation for the divider is pulled into the
        // INT value
        int rf_div_compensation = _fb_after_divider ? 1 : RFdiv;

        // Compute the actual frequency in terms of _reference_freq, N, FRAC, MOD, D, R
        // and T.
        actual_freq = (double((N + (double(FRAC) / double(MOD)))
                              * (_reference_freq * (D ? 2 : 1) / (R * (T ? 2 : 1)))))
                      / rf_div_compensation;

        uint16_t clock_div = std::max<uint16_t>(
            1, uint16_t(std::ceil(PHASE_RESYNC_TIME * pfd_freq / MOD)));
        if (clock_div > 4095) {
            // if clock_div is larger than 12-bits, increase modulus so it
            // fits. Asserts later will ensure these values are not too large
            FRAC *= (clock_div >> 12) + 1;
            MOD *= (clock_div >> 12) + 1;
            clock_div = uint16_t(std::ceil(PHASE_RESYNC_TIME * pfd_freq / MOD));
        }

        _regs.frac_12_bit          = FRAC;
        _regs.int_16_bit           = N;
        _regs.mod_12_bit           = MOD;
        _regs.clock_divider_12_bit = clock_div;
        _regs.feedback_select      = _fb_after_divider
                                    ? adf435x_regs_t::FEEDBACK_SELECT_DIVIDED
                                    : adf435x_regs_t::FEEDBACK_SELECT_FUNDAMENTAL;
        _regs.clock_div_mode = _fb_after_divider
                                   ? adf435x_regs_t::CLOCK_DIV_MODE_RESYNC_ENABLE
                                   : adf435x_regs_t::CLOCK_DIV_MODE_FAST_LOCK;
        _regs.r_counter_10_bit      = R;
        _regs.reference_divide_by_2 = T ? adf435x_regs_t::REFERENCE_DIVIDE_BY_2_ENABLED
                                        : adf435x_regs_t::REFERENCE_DIVIDE_BY_2_DISABLED;
        _regs.reference_doubler = D ? adf435x_regs_t::REFERENCE_DOUBLER_ENABLED
                                    : adf435x_regs_t::REFERENCE_DOUBLER_DISABLED;
        _regs.band_select_clock_div = uint8_t(BS);
        _regs.rf_divider_select =
            static_cast<typename adf435x_regs_t::rf_divider_select_t>(
                _get_rfdiv_setting(RFdiv));
        _regs.ldf = int_n_mode ? adf435x_regs_t::LDF_INT_N : adf435x_regs_t::LDF_FRAC_N;

        // clang-format off
        UHD_LOG_TRACE("ADF435X", boost::format(
            "ADF 435X Frequencies (MHz): REQUESTED=%0.9f, ACTUAL=%0.9f")
            % (target_freq / 1e6) % (actual_freq / 1e6));
        UHD_LOG_TRACE("ADF435X", boost::format(
            "ADF 435X Intermediates (MHz): Feedback=%0.2f, VCO=%0.2f, PFD=%0.2f, BAND=%0.2f, REF=%0.2f")
            % (feedback_freq / 1e6) % (vco_freq / 1e6) % (pfd_freq / 1e6) % (pfd_freq / BS / 1e6) % (_reference_freq / 1e6));
        UHD_LOG_TRACE("ADF435X",
            "ADF 435X Tuning: " << ((int_n_mode) ? "Integer-N" : "Fractional"));
        UHD_LOG_TRACE("ADF435X", boost::format(
            "ADF 435X Settings: R=%d, BS=%d, N=%d, FRAC=%d, MOD=%d, T=%d, D=%d, RFdiv=%d")
            % R % BS % N % FRAC % MOD % T % D % RFdiv);
        // clang-format on

        UHD_ASSERT_THROW((_regs.frac_12_bit & ((uint16_t)~0xFFF)) == 0);
        UHD_ASSERT_THROW((_regs.mod_12_bit & ((uint16_t)~0xFFF)) == 0);
        UHD_ASSERT_THROW((_regs.clock_divider_12_bit & ((uint16_t)~0xFFF)) == 0);
        UHD_ASSERT_THROW((_regs.r_counter_10_bit & ((uint16_t)~0x3FF)) == 0);

        UHD_ASSERT_THROW(vco_freq >= VCO_FREQ_MIN and vco_freq <= VCO_FREQ_MAX);
        UHD_ASSERT_THROW(RFdiv >= static_cast<uint16_t>(rf_divider_range.start()));
        UHD_ASSERT_THROW(RFdiv <= static_cast<uint16_t>(rf_divider_range.stop()));
        UHD_ASSERT_THROW(_regs.int_16_bit >= static_cast<uint16_t>(int_range.start()));
        UHD_ASSERT_THROW(_regs.int_16_bit <= static_cast<uint16_t>(int_range.stop()));

        if (flush)
            commit();
        return actual_freq;
    }

    void commit()
    {
        // reset counters
        _regs.counter_reset = adf435x_regs_t::COUNTER_RESET_ENABLED;
        std::vector<uint32_t> regs;
        regs.push_back(_regs.get_reg(uint32_t(2)));
        _write_fn(regs);
        _regs.counter_reset = adf435x_regs_t::COUNTER_RESET_DISABLED;

        // write the registers
        // correct power-up sequence to write registers (5, 4, 3, 2, 1, 0)
        regs.clear();
        for (int addr = 5; addr >= 0; addr--) {
            regs.push_back(_regs.get_reg(uint32_t(addr)));
        }
        _write_fn(regs);
    }

protected:
    uhd::range_t _get_rfdiv_range();
    int _get_rfdiv_setting(uint16_t div);

    write_fn_t _write_fn;
    adf435x_regs_t _regs;
    double _fb_after_divider;
    double _reference_freq;
    int _N_min;
    tuning_mode_t _tuning_mode;
};

template <>
inline uhd::range_t adf435x_impl<adf4350_regs_t>::_get_rfdiv_range()
{
    return uhd::range_t(1, 16);
}

template <>
inline uhd::range_t adf435x_impl<adf4351_regs_t>::_get_rfdiv_range()
{
    return uhd::range_t(1, 64);
}

template <>
inline int adf435x_impl<adf4350_regs_t>::_get_rfdiv_setting(uint16_t div)
{
    switch (div) {
        case 1:
            return int(adf4350_regs_t::RF_DIVIDER_SELECT_DIV1);
        case 2:
            return int(adf4350_regs_t::RF_DIVIDER_SELECT_DIV2);
        case 4:
            return int(adf4350_regs_t::RF_DIVIDER_SELECT_DIV4);
        case 8:
            return int(adf4350_regs_t::RF_DIVIDER_SELECT_DIV8);
        case 16:
            return int(adf4350_regs_t::RF_DIVIDER_SELECT_DIV16);
        default:
            UHD_THROW_INVALID_CODE_PATH();
    }
}

template <>
inline int adf435x_impl<adf4351_regs_t>::_get_rfdiv_setting(uint16_t div)
{
    switch (div) {
        case 1:
            return int(adf4351_regs_t::RF_DIVIDER_SELECT_DIV1);
        case 2:
            return int(adf4351_regs_t::RF_DIVIDER_SELECT_DIV2);
        case 4:
            return int(adf4351_regs_t::RF_DIVIDER_SELECT_DIV4);
        case 8:
            return int(adf4351_regs_t::RF_DIVIDER_SELECT_DIV8);
        case 16:
            return int(adf4351_regs_t::RF_DIVIDER_SELECT_DIV16);
        case 32:
            return int(adf4351_regs_t::RF_DIVIDER_SELECT_DIV32);
        case 64:
            return int(adf4351_regs_t::RF_DIVIDER_SELECT_DIV64);
        default:
            UHD_THROW_INVALID_CODE_PATH();
    }
}

#endif // INCLUDED_ADF435X_HPP