*--------1---------2---------3---------4---------5---------6---------7--

* This module produces mask permutations with the soft
* '3-out-of-4' and the firm '2-out-of-4' track patterns
* marked by '-' and '+' signs respectively

      subroutine MUTATE(Mask, Entry, HowMany)

      integer Mask, Temp, Size, Pattern(4), HowMany

      character*5 Entry(11), Null
      character*1 Hit(9)

      data Hit/'0', '1', '2', '3','4', '5', '6', '7', '8'/

      parameter (Null = '+0000')

* Computing input pattern
*----------------------------------
      Temp = Mask
      Size = 0

      do I = 1, 4
        Pattern(I) = Temp / 10**(4 - I)
        Temp = Temp - Pattern(I) * 10**(4 - I)
        if (Pattern(I).ne.0) Size = Size + 1
      end do

* Mask combinatorics
*----------------------------------

      if (Size.eq.4) then

        HowMany = 11

        Entry(1) =  '-'//Hit(Pattern(1) + 1)//Hit(Pattern(2) + 1)//
     +                   Hit(Pattern(3) + 1)//Hit(Pattern(4) + 1)

        Entry(2) =  '-'//Hit(1)//Hit(Pattern(2) + 1)//
     +                   Hit(Pattern(3) + 1)//Hit(Pattern(4) + 1)

        Entry(3) =  '-'//Hit(Pattern(1) + 1)//Hit(1)//
     +                   Hit(Pattern(3) + 1)//Hit(Pattern(4) + 1)

        Entry(4) =  '-'//Hit(Pattern(1) + 1)//Hit(Pattern(2) + 1)//
     +                   Hit(1)//Hit(Pattern(4) + 1)

        Entry(5) =  '-'//Hit(Pattern(1) + 1)//Hit(Pattern(2) + 1)//
     +                   Hit(Pattern(3) + 1)//Hit(1)

        Entry(6) =  '+'//Hit(Pattern(1) + 1)//Hit(Pattern(2) + 1)//
     +                   Hit(1)//Hit(1)

        Entry(7) =  '+'//Hit(Pattern(1) + 1)//Hit(1)//
     +                   Hit(Pattern(3) + 1)//Hit(1)

        Entry(8) =  '+'//Hit(Pattern(1) + 1)//Hit(1)//
     +                   Hit(1)//Hit(Pattern(4) + 1)

        Entry(9) =  '+'//Hit(1)//Hit(Pattern(2) + 1)//
     +                   Hit(Pattern(3) + 1)//Hit(1)

        Entry(10) = '+'//Hit(1)//Hit(Pattern(2) + 1)//
     +                   Hit(1)//Hit(Pattern(4) + 1)

        Entry(11) = '+'//Hit(1)//Hit(1)//
     +                   Hit(Pattern(3) + 1)//Hit(Pattern(4) + 1)

      else if (Size.eq.3) then

        HowMany = 4

        do I = 5, 11
	  Entry(I) = Null
	end do

        Entry(1) =  '-'//Hit(Pattern(1) + 1)//Hit(Pattern(2) + 1)//
     +                   Hit(Pattern(3) + 1)//Hit(Pattern(4) + 1)

        if (Pattern(1).eq.0) then

          Entry(2) = '+'//Hit(1)//Hit(Pattern(2) + 1)//
     +                    Hit(Pattern(3) + 1)//Hit(1)

          Entry(3) = '+'//Hit(1)//Hit(Pattern(2) + 1)//
     +                    Hit(1)//Hit(Pattern(4) + 1)

          Entry(4) = '+'//Hit(1)//Hit(1)//
     +                    Hit(Pattern(3) + 1)//Hit(Pattern(4) + 1)

        else if (Pattern(2).eq.0) then

          Entry(2) = '+'//Hit(Pattern(1) + 1)//Hit(1)//
     +                    Hit(Pattern(3) + 1)//Hit(1)

          Entry(3) = '+'//Hit(Pattern(1) + 1)//Hit(1)//
     +                    Hit(1)//Hit(Pattern(4) + 1)

          Entry(4) = '+'//Hit(1)//Hit(1)//
     +                    Hit(Pattern(3) + 1)//Hit(Pattern(4) + 1)

        else if (Pattern(3).eq.0) then

          Entry(2) = '+'//Hit(Pattern(1) + 1)//Hit(Pattern(2) + 1)//
     +                    Hit(1)//Hit(1)

          Entry(3) = '+'//Hit(Pattern(1) + 1)//Hit(1)//
     +                    Hit(1)//Hit(Pattern(4) + 1)

          Entry(4) = '+'//Hit(1)//Hit(Pattern(2) + 1)//
     +                    Hit(1)//Hit(Pattern(4) + 1)

        else if (Pattern(4).eq.0) then

          Entry(2) = '+'//Hit(Pattern(1) + 1)//Hit(Pattern(2) + 1)//
     +                    Hit(1)//Hit(1)

          Entry(3) = '+'//Hit(Pattern(1) + 1)//Hit(1)//
     +                    Hit(Pattern(3) + 1)//Hit(1)

          Entry(4) = '+'//Hit(1)//Hit(Pattern(2) + 1)//
     +                    Hit(Pattern(3) + 1)//Hit(1)

	end if
      end if

      return
      end