paradigm shift for the dsp abstraction

10 files changed, 168 insertions, 243 deletions

diff --git a/host/examples/rx_timed_samples.cpp b/host/examples/rx_timed_samples.cpp
index 1292d9b27..7b06981b2 100644
--- a/host/examples/rx_timed_samples.cpp
+++ b/host/examples/rx_timed_samples.cpp
@@ -57,7 +57,7 @@ int UHD_SAFE_MAIN(int argc, char *argv[]){
     std::cout << boost::format("Using Device: %s") % sdev->get_name() << std::endl;
 
     //set properties on the device
-    double rx_rate = sdev->get_rx_rates()[4]; //pick some rate
+    double rx_rate = 100e6/16; //FIXME get this from somewhere
     std::cout << boost::format("Setting RX Rate: %f Msps...") % (rx_rate/1e6) << std::endl;
     sdev->set_rx_rate(rx_rate);
     std::cout << boost::format("Setting device timestamp to 0...") << std::endl;
diff --git a/host/include/uhd/usrp/dsp_props.hpp b/host/include/uhd/usrp/dsp_props.hpp
index 60c0df942..75d8c0a60 100644
--- a/host/include/uhd/usrp/dsp_props.hpp
+++ b/host/include/uhd/usrp/dsp_props.hpp
@@ -24,15 +24,24 @@ namespace uhd{ namespace usrp{
 
     /*!
      * Possible device dsp properties:
-     *   A dsp can have a wide range of possible properties.
-     *   A ddc would have a properties "decim", "freq", "taps"...
-     *   Other properties could be gains, complex scalars, enables...
-     *   For this reason the only required properties of a dsp is a name
-     *   and a property to get list of other possible properties.
+     *   A dsp is a black box fpga component found between
+     *   the over-the-wire data and the codec pins.
+     *
+     *   The host rate can be modified to control resampling.
+     *   Resampling can take the form of decimation, interpolation,
+     *   or more complex fractional resampling techniques.
+     *   As usual, read back the host rate after setting it
+     *   to get the actual rate that was set (implementation dependent).
+     *
+     *   A dsp can also shift the digital stream in frequency.
+     *   Set the shift property and read it back to get actual shift.
      */
     enum dsp_prop_t{
-        DSP_PROP_NAME   = 'n', //ro, std::string
-        DSP_PROP_OTHERS = 'o'  //ro, prop_names_t
+        DSP_PROP_NAME         = 'n', //ro, std::string
+        DSP_PROP_OTHERS       = 'o', //ro, prop_names_t
+        DSP_PROP_FREQ_SHIFT   = 'f', //rw, double Hz
+        DSP_PROP_CODEC_RATE   = 'c', //ro, double Sps
+        DSP_PROP_HOST_RATE    = 'h'  //rw, double Sps
     };
 
 }} //namespace
diff --git a/host/include/uhd/usrp/mboard_props.hpp b/host/include/uhd/usrp/mboard_props.hpp
index cfc1f412e..55c11b822 100644
--- a/host/include/uhd/usrp/mboard_props.hpp
+++ b/host/include/uhd/usrp/mboard_props.hpp
@@ -42,7 +42,8 @@ namespace uhd{ namespace usrp{
         MBOARD_PROP_TX_DBOARD_NAMES = 'V', //ro, prop_names_t
         MBOARD_PROP_CLOCK_CONFIG    = 'C', //rw, clock_config_t
         MBOARD_PROP_TIME_NOW        = 't', //wo, time_spec_t
-        MBOARD_PROP_TIME_NEXT_PPS   = 'T'  //wo, time_spec_t
+        MBOARD_PROP_TIME_NEXT_PPS   = 'T', //wo, time_spec_t
+        MBOARD_PROP_STREAM_CMD      = 's'  //wo, stream_cmd_t
     };
 
 }} //namespace
diff --git a/host/include/uhd/usrp/simple_usrp.hpp b/host/include/uhd/usrp/simple_usrp.hpp
index 2d6ad2a0f..6f74a406b 100644
--- a/host/include/uhd/usrp/simple_usrp.hpp
+++ b/host/include/uhd/usrp/simple_usrp.hpp
@@ -59,7 +59,6 @@ public:
      ******************************************************************/
     virtual void set_rx_rate(double rate) = 0;
     virtual double get_rx_rate(void) = 0;
-    virtual std::vector<double> get_rx_rates(void) = 0;
 
     virtual tune_result_t set_rx_freq(double freq) = 0;
     virtual freq_range_t get_rx_freq_range(void) = 0;
@@ -77,7 +76,6 @@ public:
      ******************************************************************/
     virtual void set_tx_rate(double rate) = 0;
     virtual double get_tx_rate(void) = 0;
-    virtual std::vector<double> get_tx_rates(void) = 0;
 
     virtual tune_result_t set_tx_freq(double freq) = 0;
     virtual freq_range_t get_tx_freq_range(void) = 0;
diff --git a/host/include/uhd/usrp/subdev_props.hpp b/host/include/uhd/usrp/subdev_props.hpp
index 92d18340b..d35793c6b 100644
--- a/host/include/uhd/usrp/subdev_props.hpp
+++ b/host/include/uhd/usrp/subdev_props.hpp
@@ -39,7 +39,7 @@ namespace uhd{ namespace usrp{
         SUBDEV_PROP_QUADRATURE        = 'q', //ro, bool
         SUBDEV_PROP_IQ_SWAPPED        = 'i', //ro, bool
         SUBDEV_PROP_SPECTRUM_INVERTED = 's', //ro, bool
-        SUBDEV_PROP_LO_INTERFERES     = 'l'  //ro, bool
+        SUBDEV_PROP_USE_LO_OFFSET     = 'l'  //ro, bool
         //SUBDEV_PROP_RSSI,              //ro, float //----> not on all boards, use named prop
         //SUBDEV_PROP_BANDWIDTH          //rw, double //----> not on all boards, use named prop
     };
diff --git a/host/lib/usrp/dboard/db_basic_and_lf.cpp b/host/lib/usrp/dboard/db_basic_and_lf.cpp
index be4e646ed..930646f76 100644
--- a/host/lib/usrp/dboard/db_basic_and_lf.cpp
+++ b/host/lib/usrp/dboard/db_basic_and_lf.cpp
@@ -150,7 +150,7 @@ void basic_rx::rx_get(const wax::obj &key_, wax::obj &val){
 
     case SUBDEV_PROP_IQ_SWAPPED:
     case SUBDEV_PROP_SPECTRUM_INVERTED:
-    case SUBDEV_PROP_LO_INTERFERES:
+    case SUBDEV_PROP_USE_LO_OFFSET:
         val = false;
         return;
     }
@@ -186,7 +186,7 @@ void basic_rx::rx_set(const wax::obj &key_, const wax::obj &val){
     case SUBDEV_PROP_QUADRATURE:
     case SUBDEV_PROP_IQ_SWAPPED:
     case SUBDEV_PROP_SPECTRUM_INVERTED:
-    case SUBDEV_PROP_LO_INTERFERES:
+    case SUBDEV_PROP_USE_LO_OFFSET:
         throw std::runtime_error(str(boost::format(
             "Error: trying to set read-only property on %s subdev"
         ) % dboard_id::to_string(get_rx_id())));
@@ -258,7 +258,7 @@ void basic_tx::tx_get(const wax::obj &key_, wax::obj &val){
 
     case SUBDEV_PROP_IQ_SWAPPED:
     case SUBDEV_PROP_SPECTRUM_INVERTED:
-    case SUBDEV_PROP_LO_INTERFERES:
+    case SUBDEV_PROP_USE_LO_OFFSET:
         val = false;
         return;
     }
@@ -294,7 +294,7 @@ void basic_tx::tx_set(const wax::obj &key_, const wax::obj &val){
     case SUBDEV_PROP_QUADRATURE:
     case SUBDEV_PROP_IQ_SWAPPED:
     case SUBDEV_PROP_SPECTRUM_INVERTED:
-    case SUBDEV_PROP_LO_INTERFERES:
+    case SUBDEV_PROP_USE_LO_OFFSET:
         throw std::runtime_error(str(boost::format(
             "Error: trying to set read-only property on %s subdev"
         ) % dboard_id::to_string(get_tx_id())));
diff --git a/host/lib/usrp/simple_usrp.cpp b/host/lib/usrp/simple_usrp.cpp
index a0551a630..bd8bac00f 100644
--- a/host/lib/usrp/simple_usrp.cpp
+++ b/host/lib/usrp/simple_usrp.cpp
@@ -22,6 +22,7 @@
 #include <uhd/usrp/mboard_props.hpp>
 #include <uhd/usrp/device_props.hpp>
 #include <uhd/usrp/dboard_props.hpp>
+#include <uhd/usrp/dsp_props.hpp>
 #include <boost/foreach.hpp>
 #include <boost/format.hpp>
 #include <stdexcept>
@@ -30,17 +31,6 @@ using namespace uhd;
 using namespace uhd::usrp;
 
 /***********************************************************************
- * Helper Functions
- **********************************************************************/
-static std::vector<double> get_xx_rates(wax::obj decerps, wax::obj rate){
-    std::vector<double> rates;
-    BOOST_FOREACH(size_t decerp, decerps.as<std::vector<size_t> >()){
-        rates.push_back(rate.as<double>()/decerp);
-    }
-    return rates;
-}
-
-/***********************************************************************
  * Simple Device Implementation
  **********************************************************************/
 class simple_usrp_impl : public simple_usrp{
@@ -48,8 +38,8 @@ public:
     simple_usrp_impl(const device_addr_t &addr){
         _dev = device::make(addr);
         _mboard = (*_dev)[DEVICE_PROP_MBOARD];
-        _rx_ddc = _mboard[named_prop_t(MBOARD_PROP_RX_DSP, "ddc0")];
-        _tx_duc = _mboard[named_prop_t(MBOARD_PROP_TX_DSP, "duc0")];
+        _rx_dsp = _mboard[named_prop_t(MBOARD_PROP_RX_DSP, "ddc0")]; //FIX string crap
+        _tx_dsp = _mboard[named_prop_t(MBOARD_PROP_TX_DSP, "duc0")]; //FIX string crap
 
         //extract rx subdevice
         wax::obj rx_dboard = _mboard[MBOARD_PROP_RX_DBOARD];
@@ -86,7 +76,7 @@ public:
     }
 
     void issue_stream_cmd(const stream_cmd_t &stream_cmd){
-        _rx_ddc[std::string("stream_cmd")] = stream_cmd;
+        _mboard[MBOARD_PROP_STREAM_CMD] = stream_cmd;
     }
 
     void set_clock_config(const clock_config_t &clock_config){
@@ -101,21 +91,15 @@ public:
      * RX methods
      ******************************************************************/
     void set_rx_rate(double rate){
-        double samp_rate = _rx_ddc[std::string("if_rate")].as<double>();
-        assert_has(get_rx_rates(), rate, "simple device rx rate");
-        _rx_ddc[std::string("decim")] = size_t(samp_rate/rate);
+        _rx_dsp[DSP_PROP_HOST_RATE] = rate;
     }
 
     double get_rx_rate(void){
-        return _rx_ddc[std::string("bb_rate")].as<double>();
-    }
-
-    std::vector<double> get_rx_rates(void){
-        return get_xx_rates(_rx_ddc[std::string("decims")], _rx_ddc[std::string("if_rate")]);
+        return _rx_dsp[DSP_PROP_HOST_RATE].as<double>();
     }
 
     tune_result_t set_rx_freq(double target_freq){
-        return tune_rx_subdev_and_ddc(_rx_subdev, _rx_ddc, target_freq);
+        return tune_rx_subdev_and_ddc(_rx_subdev, _rx_dsp, target_freq);
     }
 
     freq_range_t get_rx_freq_range(void){
@@ -150,21 +134,15 @@ public:
      * TX methods
      ******************************************************************/
     void set_tx_rate(double rate){
-        double samp_rate = _tx_duc[std::string("if_rate")].as<double>();
-        assert_has(get_tx_rates(), rate, "simple device tx rate");
-        _tx_duc[std::string("interp")] = size_t(samp_rate/rate);
+        _tx_dsp[DSP_PROP_HOST_RATE] = rate;
     }
 
     double get_tx_rate(void){
-        return _tx_duc[std::string("bb_rate")].as<double>();
-    }
-
-    std::vector<double> get_tx_rates(void){
-        return get_xx_rates(_tx_duc[std::string("interps")], _tx_duc[std::string("if_rate")]);
+        return _tx_dsp[DSP_PROP_HOST_RATE].as<double>();
     }
 
     tune_result_t set_tx_freq(double target_freq){
-        return tune_tx_subdev_and_duc(_tx_subdev, _tx_duc, target_freq);
+        return tune_tx_subdev_and_duc(_tx_subdev, _tx_dsp, target_freq);
     }
 
     freq_range_t get_tx_freq_range(void){
@@ -198,8 +176,8 @@ public:
 private:
     device::sptr _dev;
     wax::obj _mboard;
-    wax::obj _rx_ddc;
-    wax::obj _tx_duc;
+    wax::obj _rx_dsp;
+    wax::obj _tx_dsp;
     wax::obj _rx_subdev;
     wax::obj _tx_subdev;
 };
diff --git a/host/lib/usrp/tune_helper.cpp b/host/lib/usrp/tune_helper.cpp
index 79a6aff7b..2fb15064c 100644
--- a/host/lib/usrp/tune_helper.cpp
+++ b/host/lib/usrp/tune_helper.cpp
@@ -18,6 +18,7 @@
 #include <uhd/usrp/tune_helper.hpp>
 #include <uhd/utils/algorithm.hpp>
 #include <uhd/usrp/subdev_props.hpp>
+#include <uhd/usrp/dsp_props.hpp>
 #include <cmath>
 
 using namespace uhd;
@@ -34,8 +35,8 @@ static tune_result_t tune_xx_subdev_and_dxc(
     wax::obj subdev_freq_proxy = subdev[SUBDEV_PROP_FREQ];
     bool subdev_quadrature = subdev[SUBDEV_PROP_QUADRATURE].as<bool>();
     bool subdev_spectrum_inverted = subdev[SUBDEV_PROP_SPECTRUM_INVERTED].as<bool>();
-    wax::obj dxc_freq_proxy = dxc[std::string("freq")];
-    double dxc_sample_rate = dxc[std::string("if_rate")].as<double>();
+    wax::obj dxc_freq_proxy = dxc[DSP_PROP_FREQ_SHIFT];
+    double dxc_sample_rate = dxc[DSP_PROP_CODEC_RATE].as<double>();
 
     // Ask the d'board to tune as closely as it can to target_freq+lo_offset
     double target_inter_freq = target_freq + lo_offset;
@@ -96,8 +97,8 @@ tune_result_t uhd::usrp::tune_rx_subdev_and_ddc(
 ){
     double lo_offset = 0.0;
     //if the local oscillator will be in the passband, use an offset
-    if (subdev[SUBDEV_PROP_LO_INTERFERES].as<bool>()){
-        lo_offset = 2.0*ddc[std::string("bb_rate")].as<double>();
+    if (subdev[SUBDEV_PROP_USE_LO_OFFSET].as<bool>()){
+        lo_offset = 2.0*ddc[DSP_PROP_HOST_RATE].as<double>();
     }
     return tune_rx_subdev_and_ddc(subdev, ddc, target_freq, lo_offset);
 }
@@ -119,8 +120,8 @@ tune_result_t uhd::usrp::tune_tx_subdev_and_duc(
 ){
     double lo_offset = 0.0;
     //if the local oscillator will be in the passband, use an offset
-    if (subdev[SUBDEV_PROP_LO_INTERFERES].as<bool>()){
-        lo_offset = 2.0*duc[std::string("bb_rate")].as<double>();
+    if (subdev[SUBDEV_PROP_USE_LO_OFFSET].as<bool>()){
+        lo_offset = 2.0*duc[DSP_PROP_HOST_RATE].as<double>();
     }
     return tune_tx_subdev_and_duc(subdev, duc, target_freq, lo_offset);
 }
diff --git a/host/lib/usrp/usrp2/dsp_impl.cpp b/host/lib/usrp/usrp2/dsp_impl.cpp
index 1fe7b7f25..559ea38d8 100644
--- a/host/lib/usrp/usrp2/dsp_impl.cpp
+++ b/host/lib/usrp/usrp2/dsp_impl.cpp
@@ -54,6 +54,16 @@ static boost::uint32_t calculate_iq_scale_word(boost::int16_t i, boost::int16_t
     return (boost::uint16_t(i) << 16) | (boost::uint16_t(q) << 0);
 }
 
+template <class rate_t> static rate_t
+pick_closest_rate(double exact_rate, const std::vector<rate_t> &rates){
+    rate_t closest_match = rates.at(0);
+    BOOST_FOREACH(rate_t possible_rate, rates){
+        if(std::abs(exact_rate - possible_rate) < std::abs(exact_rate - closest_match))
+            closest_match = possible_rate;
+    }
+    return closest_match;
+}
+
 void usrp2_impl::init_ddc_config(void){
     //create the ddc in the rx dsp dict
     _rx_dsps["ddc0"] = wax_obj_proxy::make(
@@ -81,128 +91,57 @@ void usrp2_impl::update_ddc_config(void){
     );
 }
 
-void usrp2_impl::issue_ddc_stream_cmd(const stream_cmd_t &stream_cmd){
-    //setup the out data
-    usrp2_ctrl_data_t out_data;
-    out_data.id = htonl(USRP2_CTRL_ID_SEND_STREAM_COMMAND_FOR_ME_BRO);
-    out_data.data.stream_cmd.now = (stream_cmd.stream_now)? 1 : 0;
-    out_data.data.stream_cmd.secs = htonl(stream_cmd.time_spec.secs);
-    out_data.data.stream_cmd.ticks = htonl(stream_cmd.time_spec.ticks);
-
-    //set these to defaults, then change in the switch statement
-    out_data.data.stream_cmd.continuous = 0;
-    out_data.data.stream_cmd.chain = 0;
-    out_data.data.stream_cmd.num_samps = htonl(stream_cmd.num_samps);
-
-    //setup chain, num samps, and continuous below
-    switch(stream_cmd.stream_mode){
-    case stream_cmd_t::STREAM_MODE_START_CONTINUOUS:
-        out_data.data.stream_cmd.continuous = 1;
-        break;
-
-    case stream_cmd_t::STREAM_MODE_STOP_CONTINUOUS:
-        out_data.data.stream_cmd.num_samps = htonl(0);
-        break;
-
-    case stream_cmd_t::STREAM_MODE_NUM_SAMPS_AND_DONE:
-        //all set by defaults above
-        break;
-
-    case stream_cmd_t::STREAM_MODE_NUM_SAMPS_AND_MORE:
-        out_data.data.stream_cmd.chain = 1;
-        break;
-    }
-
-    //send and recv
-    usrp2_ctrl_data_t in_data = ctrl_send_and_recv(out_data);
-    ASSERT_THROW(htonl(in_data.id) == USRP2_CTRL_ID_GOT_THAT_STREAM_COMMAND_DUDE);
-}
-
 /***********************************************************************
  * DDC Properties
  **********************************************************************/
 void usrp2_impl::ddc_get(const wax::obj &key, wax::obj &val){
-    //handle the case where the key is an expected dsp property
-    if (key.type() == typeid(dsp_prop_t)){
-        switch(key.as<dsp_prop_t>()){
-        case DSP_PROP_NAME:
-            val = std::string("usrp2 ddc0");
-            return;
-
-        case DSP_PROP_OTHERS:{
-                prop_names_t others = boost::assign::list_of
-                    ("if_rate")
-                    ("bb_rate")
-                    ("decim")
-                    ("decims")
-                    ("freq")
-                    ("stream_cmd")
-                ;
-                val = others;
-            }
-            return;
-        }
-    }
-
-    //handle string-based properties specific to this dsp
-    std::string key_name = key.as<std::string>();
-    if (key_name == "if_rate"){
-        val = get_master_clock_freq();
+    switch(key.as<dsp_prop_t>()){
+    case DSP_PROP_NAME:
+        val = std::string("usrp2 ddc0");
         return;
-    }
-    else if (key_name == "bb_rate"){
-        val = get_master_clock_freq()/_ddc_decim;
+
+    case DSP_PROP_OTHERS:
+        val = prop_names_t(); //empty
         return;
-    }
-    else if (key_name == "decim"){
-        val = _ddc_decim;
+
+    case DSP_PROP_FREQ_SHIFT:
+        val = _ddc_freq;
         return;
-    }
-    else if (key_name == "decims"){
-        val = _allowed_decim_and_interp_rates;
+
+    case DSP_PROP_CODEC_RATE:
+        val = get_master_clock_freq();
         return;
-    }
-    else if (key_name == "freq"){
-        val = _ddc_freq;
+
+    case DSP_PROP_HOST_RATE:
+        val = get_master_clock_freq()/_ddc_decim;
         return;
     }
-
-    throw std::invalid_argument(str(
-        boost::format("error getting: unknown key with name %s") % key_name
-    ));
 }
 
 void usrp2_impl::ddc_set(const wax::obj &key, const wax::obj &val){
-    //handle string-based properties specific to this dsp
-    std::string key_name = key.as<std::string>();
-    if (key_name == "decim"){
-        size_t new_decim = val.as<size_t>();
-        assert_has(
-            _allowed_decim_and_interp_rates,
-            new_decim, "usrp2 decimation"
-        );
-        _ddc_decim = new_decim; //shadow
-        update_ddc_config();
-        return;
-    }
-    else if (key_name == "freq"){
-        double new_freq = val.as<double>();
-        ASSERT_THROW(new_freq <= get_master_clock_freq()/2.0);
-        ASSERT_THROW(new_freq >= -get_master_clock_freq()/2.0);
-        _ddc_freq = new_freq; //shadow
-        this->poke32(FR_DSP_RX_FREQ,
-            calculate_freq_word_and_update_actual_freq(_ddc_freq, get_master_clock_freq())
-        );
+    switch(key.as<dsp_prop_t>()){
+
+    case DSP_PROP_FREQ_SHIFT:{
+            double new_freq = val.as<double>();
+            ASSERT_THROW(new_freq <= get_master_clock_freq()/2.0);
+            ASSERT_THROW(new_freq >= -get_master_clock_freq()/2.0);
+            _ddc_freq = new_freq; //shadow
+            this->poke32(FR_DSP_RX_FREQ,
+                calculate_freq_word_and_update_actual_freq(_ddc_freq, get_master_clock_freq())
+            );
+        }
         return;
-    }
-    else if (key_name == "stream_cmd"){
-        issue_ddc_stream_cmd(val.as<stream_cmd_t>());
+
+    case DSP_PROP_HOST_RATE:{
+            double extact_rate = get_master_clock_freq()/val.as<double>();
+            _ddc_decim = pick_closest_rate(extact_rate, _allowed_decim_and_interp_rates);
+            update_ddc_config();
+        }
         return;
-    }
 
-    throw std::invalid_argument(str(
-        boost::format("error setting: unknown key with name %s") % key_name
-    ));
+    default:
+        throw std::runtime_error("Error: trying to set read-only property on usrp2 ddc0");
+    }
 }
 
 /***********************************************************************
@@ -241,80 +180,51 @@ void usrp2_impl::update_duc_config(void){
  * DUC Properties
  **********************************************************************/
 void usrp2_impl::duc_get(const wax::obj &key, wax::obj &val){
-    //handle the case where the key is an expected dsp property
-    if (key.type() == typeid(dsp_prop_t)){
-        switch(key.as<dsp_prop_t>()){
-        case DSP_PROP_NAME:
-            val = std::string("usrp2 duc0");
-            return;
-
-        case DSP_PROP_OTHERS:{
-                prop_names_t others = boost::assign::list_of
-                    ("if_rate")
-                    ("bb_rate")
-                    ("interp")
-                    ("interps")
-                    ("freq")
-                ;
-                val = others;
-            }
-            return;
-        }
-    }
-
-    //handle string-based properties specific to this dsp
-    std::string key_name = key.as<std::string>();
-    if (key_name == "if_rate"){
-        val = get_master_clock_freq();
+    switch(key.as<dsp_prop_t>()){
+    case DSP_PROP_NAME:
+        val = std::string("usrp2 duc0");
         return;
-    }
-    else if (key_name == "bb_rate"){
-        val = get_master_clock_freq()/_duc_interp;
+
+    case DSP_PROP_OTHERS:
+        val = prop_names_t(); //empty
         return;
-    }
-    else if (key_name == "interp"){
-        val = _duc_interp;
+
+    case DSP_PROP_FREQ_SHIFT:
+        val = _duc_freq;
         return;
-    }
-    else if (key_name == "interps"){
-        val = _allowed_decim_and_interp_rates;
+
+    case DSP_PROP_CODEC_RATE:
+        val = get_master_clock_freq();
         return;
-    }
-    else if (key_name == "freq"){
-        val = _duc_freq;
+
+    case DSP_PROP_HOST_RATE:
+        val = get_master_clock_freq()/_duc_interp;
         return;
     }
-
-    throw std::invalid_argument(str(
-        boost::format("error getting: unknown key with name %s") % key_name
-    ));
 }
 
 void usrp2_impl::duc_set(const wax::obj &key, const wax::obj &val){
-    //handle string-based properties specific to this dsp
-    std::string key_name = key.as<std::string>();
-    if (key_name == "interp"){
-        size_t new_interp = val.as<size_t>();
-        assert_has(
-            _allowed_decim_and_interp_rates,
-            new_interp, "usrp2 interpolation"
-        );
-        _duc_interp = new_interp; //shadow
-        update_duc_config();
+    switch(key.as<dsp_prop_t>()){
+
+    case DSP_PROP_FREQ_SHIFT:{
+            double new_freq = val.as<double>();
+            ASSERT_THROW(new_freq <= get_master_clock_freq()/2.0);
+            ASSERT_THROW(new_freq >= -get_master_clock_freq()/2.0);
+            _duc_freq = new_freq; //shadow
+            this->poke32(FR_DSP_TX_FREQ,
+                calculate_freq_word_and_update_actual_freq(_duc_freq, get_master_clock_freq())
+            );
+        }
         return;
-    }
-    else if (key_name == "freq"){
-        double new_freq = val.as<double>();
-        ASSERT_THROW(new_freq <= get_master_clock_freq()/2.0);
-        ASSERT_THROW(new_freq >= -get_master_clock_freq()/2.0);
-        _duc_freq = new_freq; //shadow
-        this->poke32(FR_DSP_TX_FREQ,
-            calculate_freq_word_and_update_actual_freq(_duc_freq, get_master_clock_freq())
-        );
+
+    case DSP_PROP_HOST_RATE:{
+            double extact_rate = get_master_clock_freq()/val.as<double>();
+            _duc_interp = pick_closest_rate(extact_rate, _allowed_decim_and_interp_rates);
+            update_duc_config();
+        }
         return;
-    }
 
-    throw std::invalid_argument(str(
-        boost::format("error setting: unknown key with name %s") % key_name
-    ));
+    default:
+        throw std::runtime_error("Error: trying to set read-only property on usrp2 duc0");
+    }
 }
diff --git a/host/lib/usrp/usrp2/mboard_impl.cpp b/host/lib/usrp/usrp2/mboard_impl.cpp
index ceb2ec98f..0891f9dc8 100644
--- a/host/lib/usrp/usrp2/mboard_impl.cpp
+++ b/host/lib/usrp/usrp2/mboard_impl.cpp
@@ -82,6 +82,43 @@ void usrp2_impl::set_time_spec(const time_spec_t &time_spec, bool now){
     this->poke32(FR_TIME64_IMM, imm_flags);
 }
 
+void usrp2_impl::issue_ddc_stream_cmd(const stream_cmd_t &stream_cmd){
+    //setup the out data
+    usrp2_ctrl_data_t out_data;
+    out_data.id = htonl(USRP2_CTRL_ID_SEND_STREAM_COMMAND_FOR_ME_BRO);
+    out_data.data.stream_cmd.now = (stream_cmd.stream_now)? 1 : 0;
+    out_data.data.stream_cmd.secs = htonl(stream_cmd.time_spec.secs);
+    out_data.data.stream_cmd.ticks = htonl(stream_cmd.time_spec.ticks);
+
+    //set these to defaults, then change in the switch statement
+    out_data.data.stream_cmd.continuous = 0;
+    out_data.data.stream_cmd.chain = 0;
+    out_data.data.stream_cmd.num_samps = htonl(stream_cmd.num_samps);
+
+    //setup chain, num samps, and continuous below
+    switch(stream_cmd.stream_mode){
+    case stream_cmd_t::STREAM_MODE_START_CONTINUOUS:
+        out_data.data.stream_cmd.continuous = 1;
+        break;
+
+    case stream_cmd_t::STREAM_MODE_STOP_CONTINUOUS:
+        out_data.data.stream_cmd.num_samps = htonl(0);
+        break;
+
+    case stream_cmd_t::STREAM_MODE_NUM_SAMPS_AND_DONE:
+        //all set by defaults above
+        break;
+
+    case stream_cmd_t::STREAM_MODE_NUM_SAMPS_AND_MORE:
+        out_data.data.stream_cmd.chain = 1;
+        break;
+    }
+
+    //send and recv
+    usrp2_ctrl_data_t in_data = ctrl_send_and_recv(out_data);
+    ASSERT_THROW(htonl(in_data.id) == USRP2_CTRL_ID_GOT_THAT_STREAM_COMMAND_DUDE);
+}
+
 /***********************************************************************
  * MBoard Get Properties
  **********************************************************************/
@@ -179,8 +216,7 @@ void usrp2_impl::mboard_get(const wax::obj &key_, wax::obj &val){
         val = _clock_config;
         return;
 
-    case MBOARD_PROP_TIME_NOW:
-    case MBOARD_PROP_TIME_NEXT_PPS:
+    default:
         throw std::runtime_error("Error: trying to get write-only property on usrp2 mboard");
 
     }
@@ -226,27 +262,19 @@ void usrp2_impl::mboard_set(const wax::obj &key, const wax::obj &val){
         update_clock_config();
         return;
 
-    case MBOARD_PROP_TIME_NOW:{
+    case MBOARD_PROP_TIME_NOW:
         set_time_spec(val.as<time_spec_t>(), true);
         return;
-    }
 
-    case MBOARD_PROP_TIME_NEXT_PPS:{
+    case MBOARD_PROP_TIME_NEXT_PPS:
         set_time_spec(val.as<time_spec_t>(), false);
         return;
-    }
 
-    case MBOARD_PROP_NAME:
-    case MBOARD_PROP_OTHERS:
-    case MBOARD_PROP_CLOCK_RATE:
-    case MBOARD_PROP_RX_DSP:
-    case MBOARD_PROP_RX_DSP_NAMES:
-    case MBOARD_PROP_TX_DSP:
-    case MBOARD_PROP_TX_DSP_NAMES:
-    case MBOARD_PROP_RX_DBOARD:
-    case MBOARD_PROP_RX_DBOARD_NAMES:
-    case MBOARD_PROP_TX_DBOARD:
-    case MBOARD_PROP_TX_DBOARD_NAMES:
+    case MBOARD_PROP_STREAM_CMD:
+        issue_ddc_stream_cmd(val.as<stream_cmd_t>());
+        return;
+
+    default:
         throw std::runtime_error("Error: trying to set read-only property on usrp2 mboard");
 
     }