rename register to risc

seems to fit the layer much better as we really have a very reduced
instruction set

lib/risc/builtin/word.rb

@@ -0,0 +1,52 @@
+require_relative "compile_helper"
+
+module Risc
+  module Builtin
+    module Word
+      module ClassMethods
+        include CompileHelper
+
+        def putstring context
+          compiler = Vm::MethodCompiler.create_method(:Word , :putstring ).init_method
+          compiler.add_slot_to_reg( "putstring" , :message , :receiver , :new_message )
+          index = Parfait::Word.get_length_index
+          reg = RiscValue.new(:r2 , :Integer)
+          compiler.add_slot_to_reg( "putstring" , :new_message , index , reg )
+          Kernel.emit_syscall( compiler , :putstring )
+          compiler.method
+        end
+
+        # self[index] basically. Index is the first arg > 0
+        # return (and word sized int) is stored in return_value
+        def get_internal_byte context
+          compiler = compiler_for(:Word , :get_internal_byte)
+          source = "get_internal_byte"
+          me , index = self_and_int_arg(compiler,source)
+          # reduce me to me[index]
+          compiler.add_byte_to_reg( source , me , index , me)
+          # and put it back into the return value
+          compiler.add_reg_to_slot( source , me , :message , :return_value)
+          return compiler.method
+        end
+
+        # self[index] = val basically. Index is the first arg ( >0),
+        # value the second
+        # no return
+        def set_internal_byte context
+          compiler = compiler_for(:Word, :set_internal_byte , {:value => :Integer} )
+          args = compiler.method.arguments
+          len = args.instance_length
+          raise "Compiler arg number mismatch, method=#{args} " if  len != 3
+          source = "set_internal_byte"
+          me , index = self_and_int_arg(compiler,source)
+          value = load_int_arg_at(compiler , source , 2 )
+          # do the set
+          compiler.add_reg_to_byte( source , value , me , index)
+          return compiler.method
+        end
+
+      end
+      extend ClassMethods
+    end
+  end
+end