#integer related kernel functions
module Register
  module Builtin
    module Integer
      module ClassMethods
      # The conversion to base10 is quite a bit more complicated than i thought.
      # The bulk of it is in div10
      # We set up variables, do the devision and write the result to the string
      # then check if were done and recurse if neccessary
      # As we write before we recurse (save a push) we write the number backwards
      # arguments: string address , integer
      def utoa context
        utoa_function = Virtual::CompiledMethodInfo.create_method(:Integer ,:utoa ,  [ Virtual::Integer ] )
        function.info.return_type = Virtual::Integer
        function.info.receiver = Virtual::Integer
        return utoa_function
        str_addr = utoa_function.receiver
        number = utoa_function.args.first
        remainder = utoa_function.new_local
        Virtual::RegisterMachine.instance.div10( utoa_function , number  , remainder )
        # make char out of digit (by using ascii encoding) 48 == "0"
        utoa_function.instance_eval do
          add(  remainder , remainder , 48)
          strb( remainder, str_addr )
          sub(  str_addr,  str_addr ,  1 )
          cmp(  number ,  0 )
          callne( utoa_function  )
        end
        return utoa_function
      end

      def putint context
        putint_function = Virtual::CompiledMethodInfo.create_method(:Integer,:putint , [] )
        putint_function.info.return_type = Virtual::Integer
        putint_function.info.receiver = Virtual::Integer
        return putint_function
        buffer = Parfait::Word.new("           ") # create a buffer
        context.object_space.add_object buffer              # and save it (function local variable: a no no)
        int = putint_function.receiver
        moved_int = putint_function.new_local
        utoa = context.object_space.get_class_by_name(:Object).resolve_method(:utoa)
        putint_function.instance_eval do
          mov( moved_int ,  int )     # move arg up
          add( int ,  buffer ,nil )   # string to write to (add string address to pc)
          add( int , int ,  buffer.length - 3) # 3 for good measure , ahem.
          call( utoa )
          after = new_block("after_call")
          insert_at after
          # And now we "just" have to print it, using the write_stdout
          add( int ,  buffer , nil )   # string to write to
          mov( moved_int ,  buffer.length )
        end
        Virtual::RegisterMachine.instance.write_stdout(putint_function)
        putint_function
      end

      # testing method, hand coded fibo, expects arg in receiver_register
      # result comes in return_register
      # a hand coded version of the fibonachi numbers
      # not my hand off course, found in the net http://www.peter-cockerell.net/aalp/html/ch-5.html
      def fibo context
        fibo_function = Virtual::CompiledMethodInfo.create_method(:Integer,:fibo ,  [] )
        fibo_function.info.return_type = Virtual::Integer
        fibo_function.info.receiver = Virtual::Integer
        return fibo_function
        result = fibo_function.return_type
        int = fibo_function.receiver

        last = fibo_function.new_block("return")

        f1 = fibo_function.new_local
        f2 = fibo_function.new_local

        fibo_function.instance_eval do
          cmp  int , 1
          mov( result, int , condition_code: :le)
          ble( last ) #branch to return, rather than return (as the original)
          mov f1 , 1        #set up initial values
          mov f2 , 0
        end

        loop = fibo_function.new_block("loop")
        fibo_function.insert_at loop

        fibo_function.instance_eval do #loop through
          add f1 , f1 , f2             # f1 = f1 + f2
          sub f2 , f1 , f2             # f2 = f1 -f2
          sub int ,  int , 1  # todo: set.. should do below cmp, but doesn't , set_update_status: 1
          cmp int , 1
          bne( loop )
          mov( result , f1 )
        end

        fibo_function
      end
      end
      extend ClassMethods
    end
  end
end