Add value change callback for vpiPartSelect.

The __vpiPV objects express themselves as vpiPartSelect objects.
Add support for value change callbacks by attaching the callback
to the signal that we part select from.

vpi/sys_display.c

@@ -1119,6 +1119,7 @@ static PLI_INT32 sys_monitor_calltf(PLI_BYTE8*name)
 		case vpiReg:
 		case vpiIntegerVar:
 		case vpiRealVar:
+		case vpiPartSelect:
 		    /* Monitoring reg and net values involves setting
 		       a callback for value changes. Pass the storage
 		       pointer for the callback itself as user_data so

vvp/vpi_callback.cc

@@ -164,6 +164,10 @@ static struct __vpiCallback* make_value_change(p_cb_data data)
 	    vpip_array_word_change(obj, data->obj);
 	    break;
 
+	  case vpiPartSelect:
+	    vpip_part_select_value_change(obj, data->obj);
+	    break;
+
 	  case vpiModule:
 	  case vpiConstant:
 	  case vpiParameter:

vvp/vpi_priv.h

@@ -234,6 +234,10 @@ struct __vpiPV {
 extern vpiHandle vpip_make_PV(char*name, int base, int width);
 extern vpiHandle vpip_make_PV(char*name, int tbase, int twid, int width);
 
+extern struct __vpiPV* vpip_PV_from_handle(vpiHandle obj);
+extern void vpip_part_select_value_change(struct __vpiCallback*cbh, vpiHandle obj);
+
+
 /*
  * This function safely converts a vpiHandle back to a
  * __vpiSignal. Return a nil if the type is not appropriate.

vvp/vpi_signal.cc

@@ -1146,6 +1146,14 @@ static const struct __vpirt vpip_PV_rt = {
       0
 };
 
+struct __vpiPV* vpip_PV_from_handle(vpiHandle obj)
+{
+      if (obj->vpi_type->type_code == vpiPartSelect)
+	    return (__vpiPV*) obj;
+      else
+	    return 0;
+}
+
 vpiHandle vpip_make_PV(char*var, int base, int width)
 {
 
@@ -1174,3 +1182,16 @@ vpiHandle vpip_make_PV(char*var, int tbase, int twid, int width)
 
       return &obj->base;
 }
+
+void vpip_part_select_value_change(struct __vpiCallback*cbh, vpiHandle ref)
+{
+      struct __vpiPV*obj = vpip_PV_from_handle(ref);
+      assert(obj);
+
+      vvp_fun_signal_base*sig_fun;
+      sig_fun = dynamic_cast<vvp_fun_signal_base*>(obj->net->fun);
+      assert(sig_fun);
+
+	/* Attach the __vpiCallback object to the signal. */
+      sig_fun->add_vpi_callback(cbh);
+}