AC_ARG_ENABLE(debug-rwlock,
 [  --enable-debug-rwlock  Enable an RWLock that prints debug notices \
  on the screen. This is a debugging feature which should not be \
  usually enabled],
 [ debug_rwlock=yes
 ])

AC_ARG_ENABLE(states-type,
 [  --enable-states-type[=state type] Specify the states type:
                      compact [default]: Compact States
                      debug: Debug States (very slow)
                      indirect: Indirect Stack States],
 [ if   test "x$enableval" = "xcompact" ; then
      states_type=compact
   elif test "x$enableval" = "xdebug" ; then
      states_type=debug
   elif test "x$enableval" = "xindirect" ; then
      states_type=indirect
   else
      echo
      echo "Error!"
      echo "Unknown states' type"
      exit -1
   fi
 ])