RE: RE: Bit Operations

["Hewitt, Rory" <rory.hewitt@xxxxxx>]

Don,

>From Paul's post:

<snip>
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.
</snip>

It's reasons like this that I think it's a good idea to encapsulate your
"bit-twiddling" into a routine or two - even if you only need to check
one bit, it still seems more understandable (not only to you, but to the
others who will follow) to convert a field into a structure of
bit-indicators and then check those:

D BitDS          DS
D   Bit0                   N
D   Bit1                   N
D   Bit2                   N
D   Bit3                   N
D   Bit4                   N
D   Bit5                   N
D   Bit6                   N
D   Bit7                   N

C               Eval          BitDS = bitform( YourField : 1 )
C               If            Bit3 = *On
...
C               Endif 

than use %bitand:

bit3ison = %bitand(YourField:X'10') = X'10'; 
if bit3ison;
...
endif;

Plus you can use it on fields > 1-byte long - very useful for the nasty
API's like QDFRTVFD, which return multi-byte fields of bits.

In fact, given that lots of bit-twiddling processing involves IBM API's
anyway, you may as well go ahead and define structures for all of
them...

JM2CW,

Rory