User guide

7-10
VCD and VPD File Utilities
Options for Filtering Differences
The following options filter out value change differences that are
detected under certain circumstances. For the most part, these
options are additive.
-ignoretiming time
Ignores the value change when the same signal in one of the VCD
files has a different value from the same signal in the other VCD
file for less than the specified time. This is to filter out signals that
have only slightly different transition times in the two VCD files.
The vcdiff utility reports a change when there is a transition to a
different value in one of the VCD files and then a transition back
to a matching value in that same file.
-ignoreregs
Does not report value change differences on signals that are of
type register.
-ignorewires
Does not report value change differences on signals that are of
type wire.
-ignorereals
Does not report value change differences on signals that are of
type real.
-ignorefunctaskvars
Does not report value change differences on signals that are
function or task variables.
-ignorestrength (EVCD only)
EVCD files contain a richer set of signal strength and directionality
information than VCD or even VPD files. This option ignores the
strength portion of a signal value when checking for differences.