adds first version of the expanded as assembler from mikko

lib/asm/assembler.rb

@@ -0,0 +1,43 @@
+module Asm
+  ERRSTR_NUMERIC_TOO_LARGE = 'cannot fit numeric literal argument in operand'
+  ERRSTR_INVALID_ARG = 'invalid operand argument'
+
+  class Assembler
+    def initialize
+      @objects = []
+      @label_objects = []
+      @label_callbacks = []
+      @relocations = []
+    end
+    attr_reader :relocations, :objects
+
+    def add_object(obj)
+      @objects << obj
+    end
+
+    def add_relocation(*args)
+      @relocations << Asm::Relocation.new(*args)
+    end
+
+    def register_label_callback(label, io_pos, &block)
+      @label_callbacks << [label, io_pos, block]
+    end
+
+    def assemble(io)
+      @objects.each do |obj|
+        obj.assemble io, self
+      end
+
+      @relocations.delete_if do |reloc|
+        io.seek reloc.position
+        if (reloc.label.extern?)
+          reloc.handler.call(io, io.tell, reloc.type)
+        else
+          reloc.handler.call(io, reloc.label.address, reloc.type)
+        end
+        not reloc.label.extern?
+      end
+    end
+  end
+end
+