small step to making the assmebly process repeatable (is destructive at the moment)

lib/arm/constants.rb

@@ -92,6 +92,7 @@ module Arm
    #slighly wrong place for this code, but since the module gets included in instructions anyway . . .
    # implement the barrel shifter on the operand (which is set up before as an integer)
    def shift_handling
+     op = 0
      #codes that one can shift, first two probably most common.
      # l (in lsr) means logical, ie unsigned, a (in asr) is arithmetic, ie signed
      {'lsl' => 0b000, 'lsr' => 0b010, 'asr' => 0b100, 'ror' => 0b110, 'rrx' => 0b110}.each do |short, bin|
@@ -104,11 +105,12 @@ module Arm
            shift = shif.register << 1
          end
          raise "0 < shift <= 32  #{shif} #{inspect}"  if (shif >= 32) or( shif < 0)
-         @operand |=   shift(bin  , 4 )
-         @operand |=   shift(shif , 4+3)
+         op |=   shift(bin  , 4 )
+         op |=   shift(shif , 4+3)
          break
        end
      end
+     return op
    end
   end
 end