From dc6876e1c98f82e5bdf9d5c11033d0a8dd09071a Mon Sep 17 00:00:00 2001
From: Javier Arribas <javiarribas@gmail.com>
Date: Fri, 29 Mar 2019 17:36:05 +0100
Subject: [PATCH] Adding null sinks to unconnected signal conditioners
 automatically to enable partial use of multichannel sources

---
 src/core/receiver/gnss_flowgraph.cc | 23 ++++++++++++++++++++++-
 src/core/receiver/gnss_flowgraph.h  | 22 ++++++++++++----------
 2 files changed, 34 insertions(+), 11 deletions(-)

diff --git a/src/core/receiver/gnss_flowgraph.cc b/src/core/receiver/gnss_flowgraph.cc
index 95ea7df45..38563aeed 100644
--- a/src/core/receiver/gnss_flowgraph.cc
+++ b/src/core/receiver/gnss_flowgraph.cc
@@ -363,6 +363,11 @@ void GNSSFlowgraph::connect()
 #endif
 
     // Signal conditioner (selected_signal_source) >> channels (i) (dependent of their associated SignalSource_ID)
+    std::vector<bool> signal_conditioner_connected;
+    for (size_t n = 0; n < sig_conditioner_.size(); n++)
+        {
+            signal_conditioner_connected.push_back(false);
+        }
     for (unsigned int i = 0; i < channels_count_; i++)
         {
 #ifndef ENABLE_FPGA
@@ -500,10 +505,12 @@ void GNSSFlowgraph::connect()
                             top_block_->disconnect_all();
                             return;
                         }
-
+                    signal_conditioner_connected.at(selected_signal_conditioner_ID) = true;  //notify that this signal conditioner is connected
                     DLOG(INFO) << "signal conditioner " << selected_signal_conditioner_ID << " connected to channel " << i;
                 }
 #endif
+
+
             // Signal Source > Signal conditioner >> Channels >> Observables
             try
                 {
@@ -519,6 +526,20 @@ void GNSSFlowgraph::connect()
                 }
         }
 
+    //check for unconnected signal conditioners and connect null_sinks in order to provide configuration flexibility to multiband files or signal sources
+    if (configuration_->property(sig_source_.at(0)->role() + ".enable_FPGA", false) == false)
+        {
+            for (size_t n = 0; n < sig_conditioner_.size(); n++)
+                {
+                    if (signal_conditioner_connected.at(n) == false)
+                        {
+                            null_sinks_.push_back(gr::blocks::null_sink::make(sizeof(gr_complex)));
+                            top_block_->connect(sig_conditioner_.at(n)->get_right_block(), 0,
+                                null_sinks_.back(), 0);
+                            LOG(INFO) << "Null sink connected to signal conditioner " << n << " due to lack of connection to any channel" << std::endl;
+                        }
+                }
+        }
     // Put channels fixed to a given satellite at the beginning of the vector, then the rest
     std::vector<unsigned int> vector_of_channels;
     for (unsigned int i = 0; i < channels_count_; i++)
diff --git a/src/core/receiver/gnss_flowgraph.h b/src/core/receiver/gnss_flowgraph.h
index 189f34dca..32e0ea2e3 100644
--- a/src/core/receiver/gnss_flowgraph.h
+++ b/src/core/receiver/gnss_flowgraph.h
@@ -40,16 +40,17 @@
 #include "gnss_sdr_sample_counter.h"
 #include "gnss_signal.h"
 #include "pvt_interface.h"
-#include <gnuradio/msg_queue.h>      // for msg_queue, msg_queue::sptr
-#include <gnuradio/runtime_types.h>  // for basic_block_sptr, top_block_sptr
-#include <pmt/pmt.h>                 // for pmt_t
-#include <list>                      // for list
-#include <map>                       // for map
-#include <memory>                    // for for shared_ptr, dynamic_pointer_cast
-#include <mutex>                     // for mutex
-#include <string>                    // for string
-#include <utility>                   // for pair
-#include <vector>                    // for vector
+#include <gnuradio/blocks/null_sink.h>  //for null_sink
+#include <gnuradio/msg_queue.h>         // for msg_queue, msg_queue::sptr
+#include <gnuradio/runtime_types.h>     // for basic_block_sptr, top_block_sptr
+#include <pmt/pmt.h>                    // for pmt_t
+#include <list>                         // for list
+#include <map>                          // for map
+#include <memory>                       // for for shared_ptr, dynamic_pointer_cast
+#include <mutex>                        // for mutex
+#include <string>                       // for string
+#include <utility>                      // for pair
+#include <vector>                       // for vector
 #if ENABLE_FPGA
 #include "gnss_sdr_fpga_sample_counter.h"
 #endif
@@ -162,6 +163,7 @@ private:
 
     std::vector<std::shared_ptr<GNSSBlockInterface>> sig_source_;
     std::vector<std::shared_ptr<GNSSBlockInterface>> sig_conditioner_;
+    std::vector<gr::blocks::null_sink::sptr> null_sinks_;
 
     std::shared_ptr<GNSSBlockInterface> observables_;
     std::shared_ptr<GNSSBlockInterface> pvt_;