groundwork for interpreter platform

especially positioning makes the previous interpreter approach to
fragile (too far off the real thing)
Interpreter should be it’s own platform (still use the risc
instructions),
get a translator and use positions

lib/risc/machine.rb

@@ -25,23 +25,18 @@ module Risc
     attr_reader  :booted , :translated
     attr_reader  :platform
 
-    # translate to arm, ie instantiate an arm translator and pass it to translate
+    # Translate code to whatever cpu is specified.
+    # Currently only :arm and :interpret
     #
-    # currently we have no machanism to translate to other cpu's (nor such translators)
-    # but the mechanism is ready
-    def translate_arm
-      @platform = Platform.for("Arm")
-      @translated = true
-      translate(@platform.translator)
-    end
-
-    # translate code to whatever cpu the translator translates to
-    # this means translating the initial jump
+    # Translating means translating the initial jump
     # and then translating all methods
-    def translate( translator )
+    def translate( platform )
+      platform = platform.to_s.capitalize
+      @platform = Platform.for(platform)
+      @translated = true
       methods = Parfait.object_space.get_all_methods
-      translate_methods( methods , translator )
-      @cpu_init = risc_init.to_cpu(translator)
+      translate_methods( methods , @platform.translator )
+      @cpu_init = risc_init.to_cpu(@platform.translator)
     end
 
     # go through all methods and translate them to cpu, given the translator
@@ -66,6 +61,7 @@ module Risc
       raise "Must be Parfait #{const}" unless const.is_a?(Parfait::Object)
       @constants << const
     end
+
     # To create binaries, objects (and labels) need to have a position
     # (so objects can be loaded and branches know where to jump)
     #
@@ -76,7 +72,7 @@ module Risc
     # As code length amy change during assembly, this way at least the objects stay
     # in place and we don't have to deal with chaning loading code
     def position_all
-      translate_arm unless @translated
+      raise "Not translated " unless @translated
       #need the initial jump at 0 and then functions
       Position.set(cpu_init , 0 , cpu_init)
       @code_start = position_objects( @platform.padding )