!**************************************************************************
!*          Encoding an ASCII text using a random encoding table          *
!* ---------------------------------------------------------------------- *
!* The text to encode is in file codage.dat.                              *
!* The random encoding table is in file code.lst.                         *
!* The output encoded text is in file codage.lst.                         *
!*                                                                        *
!* The text can be decoded by  decodage.exe that must have access to      *
!* code.lst and codage.lst files.                                         *
!* ---------------------------------------------------------------------- *
!* SAMPLE RUN:                                                            *
!* File codage.dat contains:                                              *
!*                                                                        *
!* Program ASCII;                                                         *
!* Uses WincrtMy;                                                         *
!*                                                                        *
!* VAR                                                                    *
!*     i: word;                                                           *
!*                                                                        *
!* BEGIN                                                                  *
!*   for i:=160 to 255 do                                                 *
!*     write(i:4,' ',chr(i));                                             *
!*   Readkey;                                                             *
!*   DoneWinCrt                                                           *
!* END.                                                                   *
!*                                                                        *
!* The output file code.lst contains:                                     *
!*                                                                        *
!* t!="1#h$y%X&''<(Q)?*W+7,g-Y.s/c061;2K3/425F6i758E9@:.;}<L=!>0?w@(ATBHC *
!* uDpE[FZGRHVInJkK#LfMaNGOJP+QvR]S\TAUrVIWeXOY>Z4["\$]j^B_l`8amb{c,dSe|f *
!* %gUhxi*jMkDl_mzndoop9q&r`s3t-uNv~wqxCy:z^{)|P}b~                       *
!*                                                                        *
!* (! is coded t, " is coded =, # is coded 1, etc.)                       *
!*                                                                        *
!* The output file codage.lst contains;                                   *
!*                                                                        *
!* J&d%&8_ (]HVV.                                                         *
!* A`S` Ixz{&3fC.                                                         *
!*                                                                        *
!* r(v                                                                    *
!*     x@ ~d&,.                                                           *
!*                                                                        *
!* TpZVa                                                                  *
!*   |d& x@L6Fc 3d ;22 ,d                                                 *
!*     ~&x3S<x@/7' '7{U&<xQQ.                                             *
!*   vS8,MSC.                                                             *
!*   udzSIxzH&3                                                           *
!* pauY                                                                   *
!*                                                                        *
!*                                    F90 Release By J-P Moreau, Paris.   *
!*                                           (www.jpmoreau.fr)            *
!**************************************************************************
Program Codage

integer, parameter :: MINCAR=33     !ASCII characters from 33 to 126 only 
integer, parameter :: MAXCAR=126
integer, parameter :: MAXSTR=80     !lines of length 80 


  character*1 A(MINCAR:MAXCAR), Z(MINCAR:MAXCAR)
  integer alea,fait,i,j, Count(1)  
  character*MAXSTR ligne, codee
  real x

! initialize random generator
  Call System_Clock(Count(1))
  Call Random_Seed(Put=Count)

! open text files
  open(unit=1, file='codage.dat', action='read')
  open(unit=2, file='codage.lst', status='unknown')
  open(unit=3, file='code.lst', status='unknown')
    
  do i=MINCAR, MAXCAR 
    A(i) = ACHAR(i)
  end do	  
  
! generate a random encoding table
  Call Random_Number(x)        
  alea = INT((MAXCAR-MINCAR+1)*x)

  Z(MINCAR) = ACHAR(MINCAR+alea)  
  do i=MINCAR+1, MAXCAR
    fait=0 
    do while(fait==0)
      Call Random_Number(x)        
      alea = INT((MAXCAR-MINCAR+1)*x)	  
      Z(i) = ACHAR(MINCAR+alea)
      fait=1
      do j=MINCAR, i-1
	    ic1 = IACHAR(Z(j))
	    ic2 = IACHAR(Z(i))
        if (ic1==ic2)  fait=0
      end do
    end do
  end do

! encode input text line by line and save
10 Read(1,30,end=20) ligne
     codee = ligne
     do i=1, MAXSTR
       do j=MINCAR, MAXCAR
       	 if (IACHAR(ligne(i:i))==IACHAR(A(j)))  codee(i:i)=Z(j)
       end do
     end do
     write(2,30) codee
   goto 10
20 close(unit=1)                     
  write(2,*) ' '
  close(unit=2)

! Print random encoding table in file code.lst 
  write(3,50)  (Z(i),A(i),i=MINCAR,MAXCAR)
  write(3,*) ' '  
  close(unit=3)

  print *,' '
  print *,' Program terminated. Results in file codage.lst'
  print *,' '

50 format(70A1)
30 format(A80)

END

! end of file codage.f90