User guide

7-5
VCD and VPD File Utilities
The vcdiff Utility
The vcdiff utility compares two dump files and reports any differences
it finds. The dump file can be of type VCD, EVCD or a VPD.
Note:
vcdiff utility cannot compare dump files of different type.
Dump files consist of two sections:
• A header section that reflects the hierarchy (or some subset) of
the design that was used to create the dump file.
• A value change section, which contains all of the value changes
(and times when those value changes occurred) for all of the
signals referenced in the header.
The vcdiff utility always performs two diffs. First, it compares the
header sections and reports any signals/scopes that are present in
one dump file but are absent in the other.
The second diff compares the value change sections of the dump
files, for signals that appear in both dump files. The vcdiff utility
determines value change differences based on the final value of the
signal in a time step.