work on function entry and exit. fix stack instructions

lib/vm/function.rb

@@ -15,8 +15,8 @@ module Vm
     def initialize(name , args = [])
       super(name)
       @args = args
-      @entry = Block.new("entry_#{name}")
-      @exit = Block.new("exit_#{name}")
+      @entry = Kernel::function_entry( name )
+      @exit = Kernel::function_exit( name )
     end
     attr_reader :args , :entry , :exit
     

lib/vm/kernel.rb

@@ -1,16 +1,29 @@
 module Vm
-  module Kernel
-    def self.start
-      #TODO extract args into array of strings
-      Machine.instance.main_entry
-    end
-    def self.exit
-      # Machine.exit mov r7 , 0  + swi 0 
-      Machine.instance.main_exit
-    end
-    def self.puts string
-      # should unwrap from string to char*
-      Machine.instance.puts string
+  class Kernel
+    
+    #there are no Kernel instances, only class methods.
+    # We use this module syntax to avoid the (ugly) self.
+    module ClassMethods
+      def main_start
+        #TODO extract args into array of strings
+        Machine.instance.main_start
+      end
+      def main_exit
+        # Machine.exit mov r7 , 0  + swi 0 
+        Machine.instance.main_exit
+      end
+      def function_entry f_name
+        Machine.instance.function_entry f_name
+      end
+      def function_exit f_name
+        Machine.instance.function_exit f_name
+      end
+      def self.puts string
+        # should unwrap from string to char*
+        Machine.instance.puts string
+      end
     end
+    
+    extend ClassMethods
   end
 end

lib/vm/program.rb

@@ -28,10 +28,10 @@ module Vm
       @objects = []
       # global functions
       @functions = []
-      @entry = Vm::Kernel::start
+      @entry = Vm::Kernel::main_start
       #main gets executed between entry and exit
       @main = nil
-      @exit = Vm::Kernel::exit
+      @exit = Vm::Kernel::main_exit
     end
     attr_reader :context , :main , :functions