cwFlowTypes.h/cpp : Added var_send_to_ui().

This included the addition of ui_var_head/stub/tail and ui_callback to flow_t
and the ui_var and ui_var_link to variable_t.

cwFlowTypes.cpp

@@ -2438,6 +2438,34 @@ errLabel:
   return rc;
 }
 
+cw::rc_t  cw::flow::var_send_to_ui( variable_t* var )
+{
+
+  // var->ui_var_link is set to null when the var is removed from the list
+  
+  // 1. Atomically set _head to the new node and return 'old-head'
+  variable_t* prev   = var->proc->ctx->ui_var_head.exchange(var,std::memory_order_acq_rel);  
+
+  // Note that at this point only the new node may have the 'old-head' as it's predecssor.
+  // Other threads may therefore safely interrupt at this point.
+      
+  // 2. Set the old-head next pointer to the new node (thereby adding the new node to the list)
+  prev->ui_var_link.store(var,std::memory_order_release); // RELEASE 'next' to consumer            
+
+  return kOkRC;
+}
+
+cw::rc_t  cw::flow::var_send_to_ui( proc_t* proc, unsigned vid,  unsigned chIdx )
+{
+  rc_t rc = kOkRC;
+  variable_t* var = nullptr;
+
+  if((rc = var_find(proc, vid, chIdx, var )) == kOkRC )
+    rc = var_send_to_ui(var);
+  
+  return rc;
+}
+
 cw::rc_t cw::flow::var_register_and_set( proc_t* proc, const char* var_label, unsigned sfx_id, unsigned vid, unsigned chIdx, variable_t*& varRef )
 {
   return var_register( proc, var_label, sfx_id, vid, chIdx, nullptr, varRef );

cwFlowTypes.h

@@ -222,6 +222,8 @@ namespace cw
       struct variable_str* dst_tail;     // 
       struct variable_str* dst_link;     // Link used by dst_head list.
 
+      ui_var_t*            ui_var;       // this variables UI description
+      std::atomic<struct variable_str*> ui_var_link; // UI update var link based on flow_t ui_var_head;
     } variable_t;
 
 
@@ -377,7 +379,14 @@ namespace cw
       network_preset_t* presetA;  // presetA[presetN] partial (label and tid only) parsing of the network presets 
       unsigned          presetN;  // 
       
-      network_t* net;
+      network_t*        net;      // The root of the network instance
+
+      ui_callback_t  ui_callback;
+      void*          ui_callback_arg;
+      
+      std::atomic<variable_t*> ui_var_head; // Linked lists of var's to send to the UI
+      variable_t               ui_var_stub;
+      variable_t*              ui_var_tail;
 
     } flow_t;
 
@@ -548,6 +557,10 @@ namespace cw
     // Get all the label-sfx-id's associated with a give var label
     rc_t           var_mult_sfx_id_array( proc_t* proc, const char* var_label, unsigned* idA, unsigned idAllocN, unsigned& idN_ref );
 
+    // Send a variable value to the UI
+    rc_t           var_send_to_ui( variable_t* var );
+    rc_t           var_send_to_ui( proc_t* proc, unsigned vid,  unsigned chIdx );
+
     //-----------------
     //
     // var_register