Detecting of 'U' in a std_logic_vector

Hello,

I have to convert a std_logic_vector in an integer. This is generally no
matter. But I want to threat vectors in a special way which have 'U's or
'X'. How can I detect whether a vector only contains '0's and '1's.

Bye Tom

Thomas Reinemann

Thomas Reinemann a écrit:
> Hello,
>
> I have to convert a std_logic_vector in an integer. This is generally no
> matter. But I want to threat vectors in a special way which have 'U's or
> 'X'. How can I detect whether a vector only contains '0's and '1's.

Hi
Xor all the bits together (parity check), then pass the result through
the to_x01 function, which will return 'X' for 'U' or 'X' input. Result
should be 0 or 1 if your vector contains only 0s and 1s, or X if not.

Something like
if to_x01(xor_reduce(your_vector)) = 'X' then
...

(xor_reduce function code has been posted here a few weeks ago)

--
____ _ __ ___
| _ \_)/ _|/ _ \ Adresse de retour invalide: retirez le -
| | | | | (_| |_| | Invalid return address: remove the -
|_| |_|_|\__|\___/

Nicolas Matringe

On Thu, 28 Oct 2004 15:19:36 +0200, Nicolas Matringe
<> wrote:

>Thomas Reinemann a écrit:
>> Hello,
>>
>> I have to convert a std_logic_vector in an integer. This is generally no
>> matter. But I want to threat vectors in a special way which have 'U's or
>> 'X'. How can I detect whether a vector only contains '0's and '1's.
>
>Hi
>Xor all the bits together (parity check), then pass the result through
>the to_x01 function, which will return 'X' for 'U' or 'X' input. Result
>should be 0 or 1 if your vector contains only 0s and 1s, or X if not.
>
>Something like
> if to_x01(xor_reduce(your_vector)) = 'X' then
> ...
>
>(xor_reduce function code has been posted here a few weeks ago)

std_logic_1164 contains these functions:

FUNCTION Is_X ( s : std_ulogic_vector ) RETURN BOOLEAN;
FUNCTION Is_X ( s : std_logic_vector ) RETURN BOOLEAN;
FUNCTION Is_X ( s : std_ulogic ) RETURN BOOLEAN;


if is_x(your_vector) then

.... is much cleaner


Regards,
Allan

Allan Herriman

Allan Herriman a écrit:

> std_logic_1164 contains these functions:
>
> FUNCTION Is_X ( s : std_ulogic_vector ) RETURN BOOLEAN;
> FUNCTION Is_X ( s : std_logic_vector ) RETURN BOOLEAN;
> FUNCTION Is_X ( s : std_ulogic ) RETURN BOOLEAN;
>
>
> if is_x(your_vector) then
>
> ... is much cleaner

Didn't know that. It sure is much cleaner.

--
____ _ __ ___
| _ \_)/ _|/ _ \ Adresse de retour invalide: retirez le -
| | | | | (_| |_| | Invalid return address: remove the -
|_| |_|_|\__|\___/

Nicolas Matringe

On Wed, 03 Nov 2004 08:55:36 +0100, Nicolas Matringe
<> wrote:

>Allan Herriman a écrit:
>
>> std_logic_1164 contains these functions:
>>
>> FUNCTION Is_X ( s : std_ulogic_vector ) RETURN BOOLEAN;
>> FUNCTION Is_X ( s : std_logic_vector ) RETURN BOOLEAN;
>> FUNCTION Is_X ( s : std_ulogic ) RETURN BOOLEAN;
>>
>>
>> if is_x(your_vector) then
>>
>> ... is much cleaner
>
>Didn't know that. It sure is much cleaner.

Faster as well.

Regards,
Allan

Allan Herriman