(PHP 4 >= 4.0.2, PHP 5)
mcrypt_module_is_block_mode — Returns if the specified mode outputs blocks or not
$mode
   [, string $lib_dir
  ] )
   This function returns TRUE if the mode outputs blocks of bytes or
   FALSE if it outputs just bytes. (e.g. TRUE for cbc and ecb, and
   FALSE for cfb and stream).
  
modeOne of the MCRYPT_MODE_modename constants, or one of the following strings: "ecb", "cbc", "cfb", "ofb", "nofb" or "stream".
lib_dir
       The optional lib_dir parameter can contain the
       location where the algorithm module is on the system.
      
   This function returns TRUE if the mode outputs blocks of bytes or
   FALSE if it outputs just bytes. (e.g. TRUE for cbc and ecb, and
   FALSE for cfb and stream).