make arm use branch_lsteners

lib/arm/instructions/call_instruction.rb

@@ -41,6 +41,11 @@ module Arm
       end
     end
 
+    # if branch_to is implemented it must return the label it branches to
+    def branch_to
+      @first unless opcode == :swi
+    end
+
     def handle_call(io)
       case @first
       when Risc::Label

lib/elf/object_writer.rb

@@ -38,6 +38,7 @@ module Elf
 
       @machine.object_positions.each do |slot , position|
         next if slot.is_a?(Parfait::BinaryCode)
+        next if slot.class.name.include?("Arm")
         if( slot.respond_to? :rxf_reference_name )
           label = "#{slot.rxf_reference_name}"
         else

lib/risc/position/instruction_listener.rb

@@ -97,6 +97,7 @@ module Risc
         instruction = instruction.next
       end
       branches.each do |branch|
+        next if branch.branch_to.nil? #nil allowed for when there is no branch
         label_pos = Position.get(branch.branch_to)
         label_pos.position_listener( BranchListener.new(branch) )
       end