define vs parameter

[a2zasics]

Hi all,

I have seen a compile problem with `define. If i define same `define
in two modules, compiler warns me in NCVERILOG that a similar
definition exists, but does not in MODELSIM. Does anyone know , why
this happens, and if there is an issue using `define. Is it better in
some way to use parameters instead of `defines.

Thanks
SP

 

[MK]

The reason is probably that NCVERILOG compiles all files together (as
one big file) instead of separate compilation of each file in MODELSIM.

Try use define in command line - it should works correctly in both
simulators.

regards,
MK.

"a2zasics" <shardendu@verizon.net> wrote in message
news:1c97c9ba.0309221553.4a838522@posting.google.com...

Hi all,

I have seen a compile problem with `define. If i define same `define
in two modules, compiler warns me in NCVERILOG that a similar
definition exists, but does not in MODELSIM. Does anyone know , why
this happens, and if there is an issue using `define. Is it better in
some way to use parameters instead of `defines.

Thanks
SP

 

[Jim Wu]

I have seen a compile problem with `define. If i define same `define
in two modules, compiler warns me in NCVERILOG that a similar
definition exists, but does not in MODELSIM. Does anyone know , why
this happens, and if there is an issue using `define.

A `define'd directive takes effect from the point where it's defined until
end of the compilation or when it's redefined. Giving warnings about
redefined directives is a good thing as most of time you may not realize you
define the same diretives in multiple files. I normally put all directives
in one global definition file.

Is it better in
some way to use parameters instead of `defines.

Parametes are effective within a module. They are good for parametizable
module desgins. For state machine encodings I would recommend using
parameters.

Jim Wu
jimwu88NOOOSPAM@yahoo.com (remove capital letters)
http://www.geocities.com/jimwu88/chips

 

[KimH.K.]

use `undef directive in the end of files.

It's similar to C files header. isn't it?


"a2zasics" <shardendu@verizon.net> wrote in message
news:1c97c9ba.0309221553.4a838522@posting.google.com...

Hi all,

I have seen a compile problem with `define. If i define same `define
in two modules, compiler warns me in NCVERILOG that a similar
definition exists, but does not in MODELSIM. Does anyone know , why
this happens, and if there is an issue using `define. Is it better in
some way to use parameters instead of `defines.

Thanks
SP