Detecting of 'U' in a std_logic_vector

[Thomas Reinemann]

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

 

[Allan Herriman]

On Thu, 28 Oct 2004 15:19:36 +0200, Nicolas Matringe
<matringe.nicolas@numeri-cable.fr> 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

 

[Nicolas Matringe]

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 -
|_| |_|_|\__|\___/

 

[Allan Herriman]

On Wed, 03 Nov 2004 08:55:36 +0100, Nicolas Matringe
<matringe.nicolas@numeri-cable.fr> 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

 

[Nicolas Matringe]

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 -
|_| |_|_|\__|\___/