sim: Probe listener template with lambda (#356)

Adds a new probe listener template which can be used to instantiate with
a lambda function that is called by notify(). It is similar to
ProbeListenerArg with class but provides more flexibility. I.e. the can
be another object than the one instantiating the lambda which allows to
listen to any object. Furthermore additional parameters can be passed in
easily.

Change-Id: Iba451357182caf25097b9ae201cd5c647aff3a4f

src/sim/probe/probe.hh

@@ -1,5 +1,6 @@
 /*
  * Copyright (c) 2013 ARM Limited
+ * Copyright (c) 2022-2023 The University of Edinburgh
  * All rights reserved
  *
  * The license below extends only to copyright in the software and shall
@@ -317,6 +318,47 @@ class ProbePointArg : public ProbePoint
     }
 };
 
+
+/**
+ * ProbeListenerArgFunc generates a listener for the class of Arg and
+ * a lambda callback function that is called by the notify.
+ *
+ * Note that the function is passed as lambda function on construction
+ * Example:
+ * ProbeListenerArgFunc<MyArg> (myobj->getProbeManager(),
+ *                "MyProbePointName", [this](const MyArg &arg)
+ *                { my_own_func(arg, xyz...); // do something with arg
+ *  }));
+ */
+template <class Arg>
+class ProbeListenerArgFunc : public ProbeListenerArgBase<Arg>
+{
+  typedef std::function<void(const Arg &)> NotifyFunction;
+  private:
+    NotifyFunction function;
+
+  public:
+    /**
+     * @param obj the class of type Tcontaining the method to call on notify.
+     * @param pm A probe manager that is not part of the obj
+     * @param name the name of the ProbePoint to add this listener to.
+     * @param func a pointer to the function on obj (called on notify).
+     */
+    ProbeListenerArgFunc(ProbeManager *pm, const std::string &name,
+                       const NotifyFunction &func)
+      : ProbeListenerArgBase<Arg>(pm, name),
+        function(func)
+    {}
+
+    /**
+     * @brief called when the ProbePoint calls notify. This is a shim through
+     *        to the function passed during construction.
+     * @param val the argument value to pass.
+     */
+    void notify(const Arg &val) override { function(val); }
+};
+
+
 } // namespace gem5
 
 #endif//__SIM_PROBE_PROBE_HH__