Verilog / VHDL

Hi

I am an experienced Verilog designer and am about to start
work with a company that uses VHDL. I have been studying VHDL
and am starting to get a feel for the language. It would be good however to
be able to relate features of Verilog with equivalents in VHDL.

A specific question relates to compiler directives and command
line arguments in Verilog i.e. 'ifdef and +define+
The application is for a testbench where I want to write code to print
specific information for debug which I don't want to be printed
when the testbench executes normally. e.g. in Verilog I can write
code such as:

'ifdef debug_mode
code to print lots of debug information
'endif

There can be many of these code segments throughout the testbench
and if I want to turn them on, in the compile script I would have:

+define+debug_mode

Is there an equivalent mechanism in VHDL?

Does any body know of documents that discuss such language
equivalents?

Thanks in advance, Edward

EdwardH

EdwardH wrote:
>
> Hi
>
> I am an experienced Verilog designer and am about to start
> work with a company that uses VHDL. I have been studying VHDL
> and am starting to get a feel for the language. It would be good however to
> be able to relate features of Verilog with equivalents in VHDL.
>
> A specific question relates to compiler directives and command
> line arguments in Verilog i.e. 'ifdef and +define+
> The application is for a testbench where I want to write code to print
> specific information for debug which I don't want to be printed
> when the testbench executes normally. e.g. in Verilog I can write
> code such as:
>
> 'ifdef debug_mode
> code to print lots of debug information
> 'endif
>
> There can be many of these code segments throughout the testbench
> and if I want to turn them on, in the compile script I would have:
>
> +define+debug_mode
>
> Is there an equivalent mechanism in VHDL?
>
> Does any body know of documents that discuss such language
> equivalents?
>
> Thanks in advance, Edward

I would do a similar thing using generics,
as in this very reduced example:


entity test is

generic (debug : boolean := false); -- default

end test;

architecture single of test is

begin

single : process

begin

assert not(debug)
report "Debug Message"
severity note;

wait ; -- halt;

end process;

end single;

And then, overriding the value for the generic
when necessary, e.g for ModelSim:

vsim -Gdebug=true work.test

HTH,
Fran.

Francisco Camarero

Francisco Camarero <"camarero a"@t ee [d.ot] ethz [do.t] ch> writes:

> EdwardH wrote:
[How to do the equivalent of '+define+debug_mode' in VHDL]:
> > There can be many of these code segments throughout the testbench
> > and if I want to turn them on, in the compile script I would have:
> >
> > +define+debug_mode
> >
> > Is there an equivalent mechanism in VHDL?
> >
> > Does any body know of documents that discuss such language
> > equivalents?
>
> I would do a similar thing using generics,
> as in this very reduced example:

[snip example]

Another approach is to have a signal on the top level of your
testbench, which you manipulate using Tcl (e.g. "force -deposit
/debug_mode true").

Or even have a (text) file parser in VHDL directly, which assigns a
value to the signal in question, based on keywords in the text file.

Regards,


Kai

Kai Harrekilde-Petersen

Hi,
I use frequently the if-generate construct:

architecture HelloWorld of HelloWorld is
constant DEBUG : BOOLEAN := TRUE;
begin

GEN1:
if(DEBUG=TRUE) generate
assert (A=B) report "Error: It is not equal.";
end generate;

end HelloWorld;

Best Regards,
Slawek Grabowski

"Kai Harrekilde-Petersen" <> wrote in message
news:...
> Francisco Camarero <"camarero a"@t ee [d.ot] ethz [do.t] ch> writes:
>
> > EdwardH wrote:
> [How to do the equivalent of '+define+debug_mode' in VHDL]:
> > > There can be many of these code segments throughout the testbench
> > > and if I want to turn them on, in the compile script I would have:
> > >
> > > +define+debug_mode
> > >
> > > Is there an equivalent mechanism in VHDL?
> > >
> > > Does any body know of documents that discuss such language
> > > equivalents?
> >
> > I would do a similar thing using generics,
> > as in this very reduced example:
>
> [snip example]
>
> Another approach is to have a signal on the top level of your
> testbench, which you manipulate using Tcl (e.g. "force -deposit
> /debug_mode true").
>
> Or even have a (text) file parser in VHDL directly, which assigns a
> value to the signal in question, based on keywords in the text file.
>
> Regards,
>
>
> Kai

Slawek Grabowski