WSJT-X/lib/unpacktext.f

      subroutine unpacktext(nc1,nc2,nc3,msg)

      character*22 msg
      character*44 c
      data c/'0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZ +-./?'/

      nc3=iand(nc3,32767)                      !Remove the "plain text" bit
      if(iand(nc1,1).ne.0) nc3=nc3+32768
      nc1=nc1/2
      if(iand(nc2,1).ne.0) nc3=nc3+65536
      nc2=nc2/2

      do i=5,1,-1
         j=mod(nc1,42)+1
         msg(i:i)=c(j:j)
         nc1=nc1/42
      enddo

      do i=10,6,-1
         j=mod(nc2,42)+1
         msg(i:i)=c(j:j)
         nc2=nc2/42
      enddo

      do i=13,11,-1
         j=mod(nc3,42)+1
         msg(i:i)=c(j:j)
         nc3=nc3/42
      enddo
      msg(14:22) = '         '

      return
      end