ncverilog: 06.11-s008: (c) Copyright 1995-2007 Cadence Design Systems, Inc.
TOOL:	ncverilog	06.11-s008: Started on Feb 10, 2016 at 17:34:20 EST
ncverilog
	-c
	dff.v
	dff_tb.v
ncvlog: *E,COFILE: cannot open source file 'dff.v'.
ncvlog: *E,COFILE: cannot open source file 'dff_tb.v'.
ncvlog: *F,NOTOPL: no top-level unit found, must have recursive instances.
ncverilog: *E,VLGERR: An error occurred during parsing.  Review the log file for errors with the code *E and fix those identified problems to proceed.  Exiting with code (status 2).
TOOL:	ncverilog	06.11-s008: Exiting on Feb 10, 2016 at 17:34:20 EST  (total: 00:00:00)