User guide

D-18
Compiler Directives and System Tasks
$dumpportslimit
Specifies the maximum file size of the file specified by the
$lsi_dumpports or $dumpports system task. You specify the
file size in bytes. When the file reaches this limit VCS no longer
writes to the file. You can specify the file whose size you want to
limit or specify no particular file, in which case your specified size
limit applies to all files opened by the $lsi_dumpports or
$dumpports system task. See IEEE Std 1364-2001 page 341-
342. Syntax:
$dumpportslimit(filesize,"filename");
System Tasks for VPD Files
VPD files are files that store the transition times and values for nets
and registers but they differ from VCD files in the following ways:
• You can use the DVE to view the simulation results that VCS
recorded in a VPD file. You cannot actually load a VCD file directly
into DVE; when you load a VCD file DVE translates the file to VPD
and loads the VPD file.
• They are binary format and therefore take less disk space and
load much faster
• They can also record the order of statement execution so that you
can use the Source Window in DVE to step through the execution
of your code if you specify recording this information.
VPD files are commonly used in post-processing, where VCS writes
the VPD file during batch simulation, and then you review the
simulation results using DVE.
There are system tasks that specify the information that VCS writes
in the VPD file.