Synthesis warnings about arrays

[kb33]

Hi,

When one synthesizes arrays, Synplicity gives a whole bunch of
warnings about arrays not being included in the sensitivity list (see
example below). I was wondering if these warnings really serve any
purpose and what is the best way to suppress them (other that defining
a long single vector instead of the array, which would not be feasible
in most cases).


@W: CG290 :"C:\Documents and Settings\Class_A\Src_files\bit.v":
342:18:342:28|Referenced variable var_c_array is not in sensitivity
list

The array is defined as:
reg [3:0] var_c_array[0:23]


Thanks
Kanchan

 

[gabor]

On Aug 23, 5:46 pm, kb33 <kanchan.devarako...@gmail.com> wrote:

Hi,

When one synthesizes arrays, Synplicity gives a whole bunch of
warnings about arrays not being included in the sensitivity list (see
example below). I was wondering if these warnings really serve any
purpose and what is the best way to suppress them (other that defining
a long single vector instead of the array, which would not be feasible
in most cases).

@W: CG290 :"C:\Documents and Settings\Class_A\Src_files\bit.v":
342:18:342:28|Referenced variable var_c_array is not in sensitivity
list

The array is defined as:
reg [3:0] var_c_array[0:23]

Thanks
Kanchan

Another way is not to use always @* when your array appears
on the RHS of an assignment.

If you're comfortable that these warnings can be ignored you could
also
just use grep or something similar to filter out lines with CG290.

HTH,
Gabor

 

[Evan Lavelle]

On Fri, 24 Aug 2007 05:59:13 -0700, gabor <gabor@alacron.com> wrote:

On Aug 23, 5:46 pm, kb33 <kanchan.devarako...@gmail.com> wrote:
Hi,

Another way is not to use always @* when your array appears
on the RHS of an assignment.

but note that a conventional event control doesn't allow waiting on an
array or memory anyway, so you can't just put the array in a
sensitivity list. '@*' isn't well-defined when arrays are involved, so
that's not really a solution either (it effectively just turns into an
old-style sensitivity list with the array in it).

I think you probably need to do something about the warning.
Synplicity should synthesise to what you expect, but your simulation
may not work if you're expecting something to happen whenever a value
in your array changes.

Evan