MODULE RandomMultiplicativeFibo;

Gnu CopyLefted.

Abstract: Pseudo-random number generator by Warren D. Smith.

IMPORT RandomBasic, Word;
IMPORT RandomRep;

<* UNUSED *>
CONST
  Module = "RandomMultiplicativeFibo.";

CONST
  amf1 = 98;
  bmf1 = 27;

REVEAL
  T = TPublic BRANDED OBJECT
        imf1 := amf1;
        jmf1 := bmf1;
        arrmf1: ARRAY [0 .. amf1 - 1] OF Word.T;  (* initialize to random
                                                     odd words *)
      OVERRIDES
        init   := Init;
        engine := Engine;
      END;

PROCEDURE Init (SELF: T; initrng: RandomBasic.T; ): T =
  VAR
  BEGIN
    FOR i := amf1 - 1 TO 0 BY -1 DO
      SELF.arrmf1[i] := Word.Or(initrng.generateWord(), 2_1);
    END;
    RETURN SELF;
  END Init;

PROCEDURE Engine (SELF: T; ): Word.T =
  BEGIN
    DEC(SELF.imf1);
    DEC(SELF.jmf1);
    IF SELF.imf1 < 0 THEN
      SELF.imf1 := amf1 - 1;     (* wraparound *)
    ELSIF SELF.jmf1 < 0 THEN
      SELF.jmf1 := amf1 - 1;     (* wraparound *)
    END;
    SELF.arrmf1[SELF.imf1] :=
      Word.Times(SELF.arrmf1[SELF.imf1], SELF.arrmf1[SELF.jmf1]);
    RETURN SELF.arrmf1[SELF.imf1];
  END Engine;

BEGIN
END RandomMultiplicativeFibo.