User guide

14-27
Negative Timing Checks
VCS alters the violation windows:
- For the falling edge the window starts 40 time units before the
reference event and ends at the reference event.
- For the rising edge the window starts 20 time units before the
reference event and also ends at the reference event.
VCS alters the windows so that they overlap or converge.
2. During simulation, at time 50, the reference event, VCS displays
the timing violation:
"sourcefile.v", line_number_of_second_timing_check:
Timing violation in top.fd1_1
$setuphold( posedge cp:50 posedge d:45, limits (20,0)
);
The rising edge on signal d is in the altered violation window for
a rising edge on d that starts 20 time units before the reference
event and now ends at the reference event. The rising edge on
signal d occurs five time units before the reference event.