User guide

12-10
Delays and Timing
You specify transport delays for INTERCONNECT delays on nets
with the +transport_int_delays, +pulse_int_e/number,
and +pulse_int_r/number options. You must include all three of
these options.
If you want VCS to propagate all pulses, no matter how narrow,
specify a 0 percentage. If you want VCS to, for example, replace
pulses that are narrower than 80% of the delay with a X value pulse
(and display a warning message) and filter out pulses that are
narrower than 50% of the delay, enter the +pulse_e/80 and
+pulse_r/50 or +pulse_int_e/80 and +pulse_int_r/50
compile-time options.
Figure 12-4 shows the waveforms for the input and output ports for
an instance of a module that models a buffer with a ten time unit
module path delay. The vcs command line contains the following
compile-time options:
+transport_path_delays +pulse_e/80 +pulse_r/50
Figure 12-4 Pulse Control with Transport Delays
In the example illustrated in Figure 12-4 the following occurs:
1. At time 20 the input port toggles to 1.