Re: COBOL Bit Manipulation -- COBOL400-L

I came up with a solution.
Instead of trying to work with individual bits in a binary format, I used the decimal format to manipulate the bits, since I know how many bytes I am working with (1).
I should note I am only interested in setting the bits, not reading the bits.

Example:

01 WORK-AREA.
05 FIELD-OF-INDICATORS-2.
10 FILLER PIC X(01).
10 FIELD-OF-IND PIC X(01).
05 DEC-IND REDEFINES FIELD-OF-INDICATORS-2
PIC 9(04) BINARY.

01 BIT-VALUES.
05 BIT-1 PIC 9(04) BINARY VALUE 1.
05 BIT-2 PIC 9(04) BINARY VALUE 2.
05 BIT-3 PIC 9(04) BINARY VALUE 4.
05 BIT-4 PIC 9(04) BINARY VALUE 8.
05 BIT-5 PIC 9(04) BINARY VALUE 16.
05 BIT-6 PIC 9(04) BINARY VALUE 32.
05 BIT-7 PIC 9(04) BINARY VALUE 64.
05 BIT-8 PIC 9(04) BINARY VALUE 128.

...
PROCEDURE DIVISION
...

MOVE ZEROES TO DEC-IND.
IF SWITCH-1 = 'Y'
ADD BIT-8 TO DEC-IND
END-IF.
IF SWITCH-2 = 'Y'
ADD BIT-7 TO DEC-IND
END-IF.
IF SWITCH-3 = 'Y'
ADD BIT-6 TO DEC-IND
END-IF.

MOVE FIELD-OF-IND TO SOME-FIELD-TO-STORE-OR-USE.
...

Jason Abreu
Abreu Innovations, Inc.
jason.abreu@xxxxxxxxxxxxxxxxxxxx
http://www.abreuinnovations.com/

On 1/12/2011 3:19 PM, Jon Paris wrote:

Well Pic 1 means a single byte indicator so that won't help.

It is years since I did this but in the pre-ILE days I did it with a simple divide/multiply routine. Don't have a sample of the code handy but it is not hard to do. Depending on what you want, you can either divide by the appropriate power of 2 to shift the bit in question to the least significant position, then divide by 2 to isolate the bit in question (in the remainder) change that value as you wish and reverse the process.

If you want to test/set any arbitrary bit then it is easier to just use a divide by 2 loop and store the remainders in an array. Test/change as desired and rebuild by a repetitive multiply loop.

These days I would code it in RPGIV and use the bit oriented functions in RPG IV to do the work. Then call the RPGIV routine form the COBOL code - probably much easier.

Jon Paris

www.Partner400.com
www.SystemiDeveloper.com

On Jan 12, 2011, at 2:59 PM, Jason Abreu wrote:

Does anybody have experience with bit manipulation in COBOL?

I would like to be able to switch individual bits on/off in a single byte.

I imagined something like:

01 WORK.
05 CHAR-BYTE PIC X(01) VALUE X'40'.
05 BINARY-REP REDEFINES CHAR-BYTE.
10 BIT-1 PIC 1.
88 BIT-1-ON VALUE B'1'.
88 BIT-1-OFF VALUE B'1'.
... repeat for all 8 bits.

So usage could be something like

SET BIT-1-ON TO TRUE.
MOVE CHAR-BYTE TO FILE-FIELD.

Any ideas on this?
Thanks, ahead of time!
--
Jason Abreu
Abreu Innovations, Inc.
jason.abreu@xxxxxxxxxxxxxxxxxxxx
http://www.abreuinnovations.com/
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