more work on large moves, including the notion of linking again

lib/arm/move_instruction.rb

@@ -13,37 +13,18 @@ module Arm
       @immediate = 0      
       @rn = :r0 # register zero = zero bit pattern
       @from = Virtual::IntegerConstant.new( @from ) if( @from.is_a? Fixnum )
+      @extra = nil
     end
     
     # arm intrucions are pretty sensible, and always 4 bytes (thumb not supported)
     # but not all constants fit into the part of the instruction that is left after the instruction code,
-    # so large moves have to be split into two instrucitons. we handle this here, just this instruciton looks
+    # so large moves have to be split into two instructions. 
-    # longer
+    # we handle this "transparently", just this instruction looks longer
+    # alas, full transparency is not achieved as we only know when to use 2 instruction once we know where def the
+    # other object is, and that position is only set after code positions have been determined (in link) and so 
+    # see below in assemble 
     def mem_length
-      return 4
+      @extra ? 8 : 4
-      is_simple ? 4 : 8
-    end
-
-    # a constant (the one we want to move) can either be < 256 or be rotated in a funny arm way
-    # if neither works (not simple !) we need two instructions to make the move
-    def is_simple
-      right = @from
-      if right.is_a?(Virtual::ObjectConstant)
-        r_pos = right.position
-        # do pc relative addressing with the difference to the instuction
-        # 8 is for the funny pipeline adjustment (ie pc pointing to fetch and not execute)
-        right = Virtual::IntegerConstant.new( r_pos - self.position - 8 )
-      end
-      if (right.is_a?(Virtual::IntegerConstant))
-        if (right.fits_u8?)
-          return true
-        elsif (calculate_u8_with_rr(right))
-          return true
-        else
-          return false
-        end
-      end
-      return true
     end
 
     def assemble(io)
@@ -72,10 +53,15 @@ module Arm
           immediate = 1
           raise "hmm"
         else
-          operand = right.integer / 256
+          # and so it continues: when we notice that the const doesn't fit, first time we raise an 
-          immediate = 1
+          # error,but set the extra flag, to say the instruction is now 8 bytes
-          
+          # then on subsequent assemlies we can assemble
-          raise "cannot fit numeric literal argument in operand #{right.inspect}"
+          unless @extra
+            @extra = 1
+            raise ::Register::LinkException.new("cannot fit numeric literal argument in operand #{right.inspect}") 
+          end
+          # now we can do the actual breaking of instruction
+          raise "at leat we got here"
         end
       elsif (right.is_a?(Symbol) or right.is_a?(Virtual::Integer))
         operand = reg_code(right)    #integer means the register the integer is in (otherwise constant)

lib/register/assembler.rb

@@ -1,5 +1,6 @@
 module Register
-
+  class LinkException < Exception
+  end
   # Assmble the object space into a binary.
   # Link first to get positions, then assemble
   # link and assemble functions for each class are close to each other, so to get them the same.
@@ -36,6 +37,7 @@ module Register
     end
 
     def assemble
+      begin
         link
         @stream = StringIO.new
         mid , main = @objects.find{|k,objekt| objekt.is_a?(Virtual::CompiledMethod) and (objekt.name == :__init__ )}
@@ -51,6 +53,10 @@ module Register
           next if objekt.is_a? Virtual::CompiledMethod
           assemble_object( objekt )
         end
+      rescue LinkException => e
+        puts "coought #{e}"
+        retry
+      end
       puts "Assembled #{@stream.length.to_s(16)}"
       return @stream.string
     end

lib/register/instruction.rb

@@ -1,4 +1,3 @@
-require_relative "code"
 module Register
 
   # The register machine model is close to current hardware and has following instruction classes

lib/virtual/constants.rb

@@ -56,6 +56,10 @@ module Virtual
     def mem_length
       padded(1 + string.length)
     end
+    def set_position pos
+      puts "STRING #{pos} #{string}"
+      super
+    end
     def position
       return @position if @position
       return @string.position if @string.position

lib/virtual/object.rb

@@ -26,7 +26,10 @@ module Virtual
       @position
     end
     def set_position pos
-      raise "position set again #{pos}!=#{@position} for #{self}" if @position != nil and (@position != pos)
+      # resetting of position used to be error, but since relink and dynamic instruction size it is ok. in measures
+      if @position != nil and ((@position - pos).abs > 15)
+        raise "position set again #{pos}!=#{@position} for #{self}" 
+      end
       @position = pos
     end
     def inspect