how to use `celldefine in verilog

[zhur...@gmail.com]

I'm just a beginner in Verilog. Yesterday, I read a design containing
many `celldefine macros. For example,
`celldefine
module and21 (A1, B1, Y1);
input A1, B1;
output Y1;
wire A1, B1, Y1;
and #(0.0, 0.0) and_cell (Y1, A, B);
`endcelldefine

But I do not know much about this type of macro in Verilog. I
searched
on Internet for a while, and all what I got is just that this macro
is
used to mark a module as a cell module, and cell modules are used by
PLI rountines. In coclusion, my current understanding on this is very
shallow.

Who experienced on this point, please teach me in more detail.
I'm looking forward to any information from you.

[ABC]

Typically used for delay backannotation. Hence it is used in leaf cell
modeling.

Best regards,
ABC

[Chris Briggs]

n Sep 30, 11:56 pm, zhurim...@gmail.com wrote:
> But I do not know much about this type of macro in Verilog. I
> searched
> on Internet for a while, and all what I got is just that this macro
> is
> used to mark a module as a cell module, and cell modules are used by
> PLI rountines. In coclusion, my current understanding on this is very
> shallow.

Also see your simulator manual to see what it does with `celldefine. I
think most of them can make use of it to automatically exclude library
cells from waves if you want. I've added `celldefine/endcelldefine to
some of my vendor library files for this reason. You can add
`celldefine at the top and `endcelldefine at the bottom of a file
containing lots of modules and they'll all be included in the
definition.

-cb

[Kevin Neilson]

If you are a beginner, I suggest forgetting about this macro. You will
probably never use anything like it; in fact, you may never need to
create timing-accurate models.
-Kevin