remove NotSame from risc

instead use a - b and then  isZero

lib/mom/instruction/not_same_check.rb

@@ -6,6 +6,8 @@ module Mom
   # The values that are compared are defined as SlotDefinitions, ie can be anything
   # available to the machine through frame message or self
   #
+  # Acording to Mom::Check logic, we jump to the given label is the values are the same
+  #
   class NotSameCheck < Check
     attr_reader :left , :right
 
@@ -14,12 +16,13 @@ module Mom
       @left , @right  = left , right
     end
 
-    # basically move both left and right values into register and issue a
-    # risc comparison
+    # basically move both left and right values into register
+    # subtract them and see if IsZero comparison
     def to_risc(compiler)
       l_val = left.to_register(compiler, self)
       r_val = right.to_register(compiler, self)
-      check = Risc::NotSame.new(self, l_val.register, r_val.register, false_jump.to_risc(compiler))
+      check = Risc.op( self , :- , l_val.register , r_val.register)
+      check << Risc::IsZero.new( self, false_jump.to_risc(compiler))
       l_val << r_val << check
     end
   end

lib/risc/instructions/branch.rb

@@ -75,14 +75,6 @@ module Risc
     end
   end
 
-  # branch if two registers contain different values
-  class NotSame < Branch
-    attr_reader :left , :right
-    def initialize(source , left , right , label)
-      super(source , label)
-    end
-  end
-
   class Unconditional < Branch
 
   end
@@ -90,7 +82,7 @@ module Risc
   class IsZero < Branch
   end
 
-  class IsNotzero < Branch
+  class IsNotZero < Branch
   end
 
   class IsMinus < Branch