User guide

12-8
Delays and Timing
• Have VCS replace even narrower pulses with an X value pulse
on the output and display a warning message.
• Have VCS then filter out and ignore pulses that are even narrower
that the ones for which it propagates an X value pulse and displays
an error message.
You specify pulse control with the +pulse_e/number and
+pulse_r/number compile-time options for module path delays
and the +pulse_int_e/number and +pulse_int_r/number
compile-time options for INTERCONNECT delays.
The +pulse_e/number option’s number argument specifies a
percentage of the module path delay. VCS replaces pulses whose
widths that are narrower than the specified percentage of the delay
with an X value pulse on the output or inout port and displays a
warning message.
Similarly, the +pulse_int_e/number option’s number argument
specifies a percentage of the INTERCONNECT delay. VCS replaces
pulses whose widths are narrower than the specified percentage of
the delay with an X value pulse on the inout or output port instance
that is the load of the net to which you backannotated the
INTERCONNECT delay. It also displays a warning message.
The +pulse_r/number option’s number argument also specifies a
percentage of the module path delay. VCS filters out the pulses whose
widths are narrower than the specified percentage of the delay. With
these pulses there is no warning message; VCS simply ignores these
pulses.
Similarly, the +pulse_int_r/number option’s number argument
specifies a percentage of the INTERCONNECT delay. VCS filters out
pulses whose widths are narrower than the specified percentage of
the delay. There is no warning message with these pulses.