subroutine entsrc(irold,irnew)
  c
  c  this routine returns irold = lrecov and sets lrecov = irnew.
  c
  c  if there is an active error state, the message is printed
  c  and execution stops.
  c
  c  irnew = 0 leaves lrecov unchanged, while
  c  irnew = 1 gives recovery and
  c  irnew = 2 turns recovery off.
  c
  c  error states -
  c
  c    1 - illegal value of irnew.
  c    2 - called while in an error state.
  c
        external i8save
  c
        if (irnew.lt.0 .or. irnew.gt.2)
       1   call seterr(31hentsrc - illegal value of irnew,31,1,2)
  c
        irold=i8save(2,irnew,irnew.ne.0)
  c
  c  if have an error state, stop execution.
  c
        if (i8save(1,0,.false.) .ne. 0) call seterr
       1   (39hentsrc - called while in an error state,39,2,2)
  c
        return
  c
        end