3 files changed, 54 insertions, 1 deletions
diff --git a/gr-blocks/grc/blocks_selector.block.yml b/gr-blocks/grc/blocks_selector.block.yml
index 86a009e6e9..0b8e1ef696 100644
--- a/gr-blocks/grc/blocks_selector.block.yml
+++ b/gr-blocks/grc/blocks_selector.block.yml
@@ -55,6 +55,14 @@ inputs:
     id: en
     optional: true
     hide: ${ showports }
+-   domain: message
+    id: iindex
+    optional: true
+    hide: ${ showports }
+-   domain: message
+    id: oindex
+    optional: true
+    hide: ${ showports }
 
 outputs:
 -   domain: stream
diff --git a/gr-blocks/lib/selector_impl.cc b/gr-blocks/lib/selector_impl.cc
index dafb5f9096..53a5a0992a 100644
--- a/gr-blocks/lib/selector_impl.cc
+++ b/gr-blocks/lib/selector_impl.cc
@@ -55,7 +55,12 @@ selector_impl::selector_impl(size_t itemsize,
     message_port_register_in(pmt::mp("en"));
     set_msg_handler(pmt::mp("en"), [this](pmt::pmt_t msg) { this->handle_enable(msg); });
 
-    // TODO: add message ports for input_index and output_index
+    message_port_register_in(pmt::mp("iindex"));
+    set_msg_handler(pmt::mp("iindex"),
+                    [this](pmt::pmt_t msg) { this->handle_msg_input_index(msg); });
+    message_port_register_in(pmt::mp("oindex"));
+    set_msg_handler(pmt::mp("oindex"),
+                    [this](pmt::pmt_t msg) { this->handle_msg_output_index(msg); });
 }
 
 selector_impl::~selector_impl() {}
@@ -78,6 +83,44 @@ void selector_impl::set_output_index(unsigned int output_index)
         throw std::out_of_range("output_index must be < noutputs");
 }
 
+void selector_impl::handle_msg_input_index(pmt::pmt_t msg)
+{
+    pmt::pmt_t data = pmt::cdr(msg);
+
+    if (pmt::is_integer(data)) {
+        const unsigned int new_port = pmt::to_long(data);
+
+        if (new_port < d_num_inputs)
+            set_input_index(new_port);
+        else
+            GR_LOG_WARN(
+                d_logger,
+                "handle_msg_input_index: port index greater than available ports.");
+    } else
+        GR_LOG_WARN(
+            d_logger,
+            "handle_msg_input_index: Non-PMT type received, expecting integer PMT");
+}
+
+void selector_impl::handle_msg_output_index(pmt::pmt_t msg)
+{
+    pmt::pmt_t data = pmt::cdr(msg);
+
+    if (pmt::is_integer(data)) {
+        const unsigned int new_port = pmt::to_long(data);
+        if (new_port < d_num_outputs)
+            set_output_index(new_port);
+        else
+            GR_LOG_WARN(
+                d_logger,
+                "handle_msg_output_index: port index greater than available ports.");
+    } else
+        GR_LOG_WARN(
+            d_logger,
+            "handle_msg_output_index: Non-PMT type received, expecting integer PMT");
+}
+
+
 void selector_impl::handle_enable(pmt::pmt_t msg)
 {
     if (pmt::is_bool(msg)) {
diff --git a/gr-blocks/lib/selector_impl.h b/gr-blocks/lib/selector_impl.h
index e11068d805..fe4b36f9f1 100644
--- a/gr-blocks/lib/selector_impl.h
+++ b/gr-blocks/lib/selector_impl.h
@@ -47,6 +47,8 @@ public:
     void forecast(int noutput_items, gr_vector_int& ninput_items_required);
     bool check_topology(int ninputs, int noutputs);
     void setup_rpc();
+    void handle_msg_input_index(pmt::pmt_t msg);
+    void handle_msg_output_index(pmt::pmt_t msg);
     void handle_enable(pmt::pmt_t msg);
     void set_enabled(bool enable)
     {