User guide

17-4
Using the PLI
To use the debugging features, do the following:
1. Write a PLI table file, limiting the scope and operations of the ACC
routines used by the debugging features.
2. Compile and simulate your design, specifying the table file.
These procedures are not mutually exclusive. It is, for example, quite
possible that you have a PLI application that you write and use during
the debugging phase of your design. If so you can write a PLI table
file that both:
• Associates user-defined system tasks or system functions with
the functions in your application and limits the scope and
operations of the ACC routines called by your functions for faster
performance.
• Limits scope and operations of the ACC routines called by the
debugging features in VCS.
Functions in a PLI Application
When you write a PLI application you typically write a number of
functions. The following are PLI functions that VCS expects with a
user-defined system task or system function:
• The function that VCS calls when it executes the user-defined
system task. Other functions are not necessary but this call
function must be present. It’s not unusual for there to be more
than one call function. You’ll need a separate user-defined system
task for each call function. If the function returns a value then you
must write a user-defined system function for it instead of a
user-defined system task.