Hi Team,
I have an integer field where each bit means something.
How can I test a bit in the integer value/field in a filter?

Regards & TIA,
Ian

On 7/22/2021 5:55 PM, Ian Branch wrote:
> Hi Team,
> I have an integer field where each bit means something.
> How can I test a bit in the integer value/field in a filter?

Have not tested in filter but divide by the value corresponding to bit
position (power of 2 basically) and then use MOD 2 to see if last bit is
1. use floor to ensure int values.

Basically

Value mod 2 = 1 if last bit is set
(floor(value/2)) mod 2=1 for 2nd last
(floor(value/4)) mod 2=1 for 3nd last etc


Raul

Thanks Raul.  Messy when testing several bits but it works.  
I have asked Tim to consider a BitTest() function in Filtering..  i.e. BitTest(fieldName, bit)  return true or false of set or not.

Regards & Tks again,
Ian

Raul


Wow - colour me impressed

Roy Lambert

Ian


To build on Raul's post - why not set up computed (or generated) columns to represent each bit. Should make accessing easier

Roy Lambert

Show off.  

Ian


Yeah - but I'm pretty with it

Roy Lambert (posting as a compulsive liar)

> To build on Raul's post - why not set up computed (or generated) columns to represent each bit. Should make accessing easier

Or create your own function in the schema...

CREATE FUNCTION "IsBitSet" (IN "Value" INTEGER, IN "BitPos" SMALLINT)
RETURNS BOOLEAN
BEGIN
DECLARE lValue INTEGER;
DECLARE Result Boolean default False;
IF (BitPos >= 0) and (BitPos <= 31) THEN
 SET lValue = FLOOR(Value/POWER(2, BitPos));
 SET Result = lValue mod 2 = 1;
END IF;
Return Result;
END
VERSION 1.00

Hi Terry,
Interesting thought.
How would I use that in an EDBTable filter?

Regards,
Ian

(P.S.  I have filed that little bit of code away for future reference.)

> How would I use that in an EDBTable filter?

Just like any other filter condition.  If you are filtering on the column "ABC"...

Table.Filter := 'IsBitSet(ABC, 0)'
Table.Filtered := True;