User guide

17-5
Using the PLI
• The function that VCS calls during compilation to check if the
user-defined system task has the correct syntax. You can omit
this check function.
• The function that VCS calls for miscellaneous reasons such as
the execution of $stop, or $finish, or other reasons such a
value change. When VCS calls this function it passes a reason
argument to it that explains why VCS is calling it. You can omit
this miscellaneous function.
These functions are the ones you tell VCS about in the PLI table file;
apart from these PLI applications can have several more functions
that are called by other functions.
Note:
You do not specify a function to determine the return value size
of a user-defined system function; instead you specify the size
directly in the PLI table file.
Header Files for PLI Applications
For PLI applications you need to include one or more of the following
header files:
acc_user.h
For PLI Applications whose functions call IEEE Standard ACC
routines as documented in the IEEE Verilog language reference
manual.
vcsuser.h
For PLI applications whose functions call IEEE Standard TF
routines as documented in the IEEE Verilog language reference
manual.