User guide

17-3
VCD+ (vpd) File Generation
VCD+ has command-line options that affect performance and file
sizes. These options, presented in subsequent sections, allow the
user to run VCD+ in the most effective manner. To optimize
simulator performance and VCD+ file size, consider the size of
the design, the RAM memory capacity of the user workstation,
swap space, disk storage limits, and the methodology used in the
project.
Note:
For simulators other than VCS, the VirSim PLI must be linked to
your simulator executable. Refer to the Installation Notes
distributed with the VirSim software.
System Tasks and Functions
VCD+ system tasks are used to capture and save value change data
in a binary format so that the data can be viewed in the Waveform
Window, Register Window, Source Window, and Logic Browser. The
following VCD+ system tasks may be included in source files or
entered at the simulator interactive prompt:
System Tasks to Generate a VCD+ File
Note:
The $vcdpluson and $vcdplusoff system tasks accept the
same arguments as the Verilog $dumpvars system task. Unlike
standard VCD, this lets you turn recording on or off for variables
during the same simulation.