DEFINITION MODULE ShuffleFast;

(*
 These routines are for randomly picking numbers from a sequential list
 so that no number is picked more than once.
 Applications are card shuffling type operations where a set of objects
 need to be rearranged/picked randomly.

 First call Create to build a list, then use Next to get numbers randomly.
 Call Reset to reset the list to have all 'size' numbers available again.
 If Next is called more than 'size' times, a Reset will be forced.
*)

(* John Andrea, Apr.2/92 *)
(* This code may be freely used and distributed, it may not be sold *)


EXPORT QUALIFIED Deck, Create, Reset, Next;


TYPE
    Deck;   (* opaque *)

PROCEDURE Create( VAR d :Deck; size :CARDINAL );

PROCEDURE Reset( d :Deck );

PROCEDURE Next( d :Deck ) :CARDINAL;

END ShuffleFast.