small fixes

lib/register/register_reference.rb

@@ -10,9 +10,6 @@ module Register
     attr_accessor :symbol
 
     def initialize r
-      if( r.is_a? Fixnum)
-        r = "r#{r}".to_sym
-      end
       raise "wrong type for register init #{r}" unless r.is_a? Symbol
       raise "double r #{r}" if r == :rr1
       @symbol = r

lib/virtual/parfait_adapter.rb

@@ -20,8 +20,9 @@ module FakeMem
     raise "Class not found #{vm_name}" unless clazz
     self.set_layout clazz.object_layout
   end
+  #TODO, this is copied from module Positioned, maybe avoid duplication ?
   def position
-    raise "position accessed but not set at #{length} for #{self.inspect[0...500]}" if @position == nil
+    raise "position accessed but not set at #{mem_length} for #{self.inspect[0...1000]}" if @position == nil
     @position
   end
   def set_position pos
@@ -88,7 +89,9 @@ module Parfait
     def to_s
       Sof::Writer.write(self)
     end
-
+    def inspect
+      to_s
+    end
   end
   class List
     def mem_length

lib/virtual/positioned.rb

@@ -2,7 +2,7 @@ require_relative "type"
 
 module Positioned
   def position
-    raise "position accessed but not set at #{length} for #{self.inspect[0...500]}" if @position == nil
+    raise "position accessed but not set at #{mem_length} for #{self.inspect[0...500]}" if @position == nil
     @position
   end
   def set_position pos