implement arm branches

which backfired into interpreter as
plus actually means 0 or plus in arm
may still change back but for now

lib/arm/translator.rb

@@ -78,6 +78,10 @@ module Arm
         c = ArmMachine.orr(left , left , right)
       when "*"
         c = ArmMachine.mul(left , right , left) #arm rule about left not being result, lukily commutative
+      when ">>"
+        c = ArmMachine.mov(left , left , :shift_asr => right) #arm rule about left not being result, lukily commutative
+      when "<<"
+        c = ArmMachine.mov(left , left , :shift_lsl => right) #arm rule about left not being result, lukily commutative
       else
         raise "unimplemented  '#{code.operator}' #{code}"
       end
@@ -92,6 +96,22 @@ module Arm
       ArmMachine.b( code.label )
     end
 
+    def translate_IsPlus code
+      ArmMachine.bpl( code.label)
+    end
+
+    def translate_IsMinus code
+      ArmMachine.bmi( code.label)
+    end
+
+    def translate_IsZero code
+      ArmMachine.beq( code.label)
+    end
+
+    def translate_IsOverflow code
+      ArmMachine.bvs( code.label)
+    end
+
     def translate_Syscall code
       call_codes = { :putstring => 4 , :exit => 1    }
       int_code = call_codes[code.name]

lib/interpreter/interpreter.rb

@@ -59,7 +59,7 @@ module Interpreter
       old = get_register( reg ) # also ensures format
       if val.is_a? Fixnum
         @flags[:zero] = (val == 0)
-        @flags[:plus] = (val > 0)
+        @flags[:plus] = (val >= 0)
         @flags[:minus] = (val < 0)
         log.debug "Set_flags #{val}  :#{@flags.inspect}"
       else