RE: Bit Operations

[Paul Jackson <pjackson@xxxxxxxxxx>]

To do an equivalent of TESTB '3' (which tests the fourth bit from the left)
you would need to do a:

bit3ison = %BitAnd(YourField:X'10') = X'10';

where bit3ison is a named indicator field.

This compares your field with 0001 0000.

if your field has the fourth bit equal to '1', only the fourth position will
return a true '1' bit everything else will be '0' - hence a result of X'10'.

If your fourth bit is not 1 then no bits will match and the result will be
X'00'

Hope this helps!

-----Original Message-----
From: rpg400-l-bounces@xxxxxxxxxxxx
[mailto:rpg400-l-bounces@xxxxxxxxxxxx]On Behalf Of Barbara Morris
Sent: Friday, May 27, 2005 3:49 PM
To: rpg400-l@xxxxxxxxxxxx
Subject: Re: Bit Operations


"Fisher, Don" wrote:
> 
> I've read the manual and searched the archives yet still don't understand
> this.  There is a character field returned by an IBM a.p.i. that contains
> information in individual bits (bit 0 is something, bit 1 is something
else,
> and so on) so I need a method of testing specific bits of this one
character
> field.  As near as I can tell, the following code should test bit 3 in the
> field to determine if it's on:
> IF %BITAND(Field : x'F3') <> x'00'
> 

If you're counting the bits starting at 1 from left to right (or top to
bottom from the API documentation), you want to compare your field to
bits '0010 0000' which is x'20'.  If you mean what TESTB '3' means, you
want to compare your field to bits '0000 1000' = x'08'.

TESTB handles a factor 2 of '3' differently from a factor 2 of x'F3',
even though '3' and x'f3' are the same value.
   '3'   means bits '0000 1000' = x'08'
   x'F3' means bits '1111 0011' 
%BITAND behaves like the x'F3' form, but I'm guessing you want the '3'
behaviour, x'08'.