rem: if( AHIDevice != NULL )
add: if( AHIDevice == 0 )
context: CloseAHI( void ){  if( AHIDevice != NULL )  {    CloseDevice( (struct IORequest *) AHIio );  }  DeleteIORequest( (struct IORequest *) AHIio );  DeleteMsgPort( AHImp );  AHIBase   = NULL;  AHImp     = NULL;  AHIio     = NULL;  AHIDevice = IOERR_OPENFAIL;}