# File word_setup.ML

    (*  Title:      HOL/Library/word_setup.ML
        ID:         $Id: word_setup.ML,v 1.5 2005/06/20 20:13:59 wenzelm Exp $
        Author:     Sebastian Skalberg (TU Muenchen)

    comments containing lcp are the removal of fast_bv_of_nat.
    *)

    local
        fun is_const_bool (Const("True",_)) = true
          | is_const_bool (Const("False",_)) = true
          | is_const_bool _ = false
        fun is_const_bit (Const("Word.bit.Zero",_)) = true
          | is_const_bit (Const("Word.bit.One",_)) = true
          | is_const_bit _ = false
        fun num_is_usable (Const("Numeral.Pls",_)) = true
          | num_is_usable (Const("Numeral.Min",_)) = false
          | num_is_usable (Const("Numeral.Bit",_) $ w $ b) =
    	num_is_usable w andalso is_const_bool b
          | num_is_usable _ = false
        fun vec_is_usable (Const("List.list.Nil",_)) = true
          | vec_is_usable (Const("List.list.Cons",_) $ b $ bs) =
    	vec_is_usable bs andalso is_const_bit b
          | vec_is_usable _ = false
        fun add_word thy =
    	let
     (*lcp**	    val fast1_th = PureThy.get_thm thy "Word.fast_nat_to_bv_def"**)
    	    val fast2_th = PureThy.get_thm thy (Name "Word.fast_bv_to_nat_def")
     (*lcp**	    fun f sg thms (Const("Word.nat_to_bv",_) $ (Const("Numeral.number_of",_) $ t)) =
    		if num_is_usable t
    		then SOME (Drule.cterm_instantiate [(cterm_of sg (Var(("w",0),Type("Numeral.bin",[]))),cterm_of sg t)] fast1_th)
    		else NONE
    	      | f _ _ _ = NONE **)
    	    fun g sg thms (Const("Word.bv_to_nat",_) $ (t as (Const("List.list.Cons",_) $ _ $ _))) =
    		if vec_is_usable t
    		then SOME (Drule.cterm_instantiate [(cterm_of sg (Var(("bs",0),Type("List.list",[Type("Word.bit",[])]))),cterm_of sg t)] fast2_th)
    		else NONE
    	      | g _ _ _ = NONE
      (*lcp**	    val simproc1 = Simplifier.simproc (sign_of thy) "nat_to_bv" ["Word.nat_to_bv (number_of ?w)"] f ***)
    	    val simproc2 = Simplifier.simproc (sign_of thy) "bv_to_nat" ["Word.bv_to_nat (?x # ?xs)"] g
    	in
    	    Simplifier.change_simpset_of (op addsimprocs) [(*lcp*simproc1,**)simproc2] thy
    	end
    in
    val setup_word = [add_word]
    end