module Asm

  class Shift 
    attr_accessor :type, :value, :argument
  end

  # Registers have off course a name (r1-16 for arm)
  # but also refer to an address. In other words they can be an operand for instructions.
  # Arm has addressing modes abound, and so can add to a register before actually using it
  # If can actually shift or indeed shift what it adds, but not implemented
  class Register 
    attr_accessor :name , :offset , :bits
    def initialize name , bits
      @name = name
      @bits = bits
      @offset = 0 
    end
    
    # this is for the dsl, so we can write pretty code like r1 + 4
    # when we want to access the next word (4) after r1
    def + number
      @offset = number
      self
    end
  end

  # maybe not used at all as code_gen::instruction raises if used.
  # instead now using Arrays
  class RegisterList 
    attr_accessor :registers
    def initialize regs
      @registers = regs
      regs.each{ |reg| raise  "not a reg #{sym} , #{reg}" unless reg.is_a?(Asm::Register) }
    end
  end

  class NumLiteral 
    attr_accessor :value
    def initialize val
      @value = val
    end
  end

end