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#468 document binary operators

Programmer's Guide
closed
Vincent (Bryan) Coen
None
5 - default
2024-06-12
2024-03-14
Simon Sobisch
No

Those were backported into GnuCOBOL 3.2, but as no one passed the information (other than the NEWS entry), this is currently missing in the PG.

From the standard (2023):

A boolean operator specifies the type of boolean operation to be performed on one or two operands, for a unary operator or binary operator, respectively. The following are the boolean operators:

Binary boolean operators Meaning
B-AND AND operation (boolean conjunction)
B-OR Inclusive OR operation (boolean inclusive disjunction)
B-XOR Exclusive OR operation (boolean exclusive disjunction)
Unary boolean operator Meaning
B-NOT Negation operation
Boolean shift operators Meaning
B-SHIFT-L SHIFT LEFT operation
B-SHIFT-LC Circular SHIFT LEFT operation
B-SHIFT-R SHIFT RIGHT operation
B-SHIFT-RC Circular SHIFT RIGHT operation

The shift operators existed in other dialects before they were added to the standard, B-SHIFT-L->B-LEFT + B-SHIFT-R->B-RIGHT; which is also supported by GnuCOBOL (if you don't use a strict dialect that does not have these reserved words). They operate on the binary value (no packing/unpacking done).

The binary operators can be used in computations or expressions. Both sides can be a numeric item or literal (including the special hex notations; see samples in tests/testsuite.src/run_extensions.at.

More quoting:

Evaluation of a boolean expression shall proceed as follows:
a) [... parentheses ...]
b) The precedence of operations at the same level of inclusiveness, is:
1st — negation (B-NOT)
2nd — conjunction (B-AND)
3rd — exclusive disjunction (B-XOR)
4th — inclusive disjunction (B-OR)
The precedence of boolean shift operations (B-SHIFT-L, B-SHIFT-R, B-SHIFT-LC and B-SHIFT-RC) is the same as that of the preceding operation, if any. If the boolean shift operation is not preceded by another operation, the precedence of that operation is the same as B-AND.
c) When the sequence of evaluation is not specified by parentheses, the evaluation of operations with the same precedence shall proceed from left to right.

Discussion

  • Simon Sobisch

    Simon Sobisch - 2024-03-14

    @dilodilo Do you think we need more information here?

     

    • Eugenio Di Lorenzo

      Eugenio Di Lorenzo - 2024-03-14

      Wow, This is very cool.

      I think a new Chapter should be inserted after 2.2.4. Arithmetic Expressions.
      The new Chapter will be: 2.2.5 Boolean Expression.

      Insert first of all the Syntax:

      Boolean-Expression Syntax

      [ Operand-1 ] { Boolean-Operator } Operand-2

      and in this new chapter insert the exact text of your previous post
      (be careful ... in your post there is a typo error: B-SHIFT-L SHIFT must be B-SHIFT-L)

      I would then add the following table:

      Examples of Boolean Operations
+-----------------------------------------------------------------+ 
| Boolean operation     |operand-1| Operator   |operand-2| Result |
+-----------------------+---------+------------+---------+--------+
| Conjunction           |  1100   | B-AND      |  0101   |  0100  |
| Inclusive disjunction |  1100   | B-OR       |  0101   |  1101  |
| Exclusive disjunction |  1100   | B-XOR      |  0101   |  1001  |
| Negation              |    -    | B-NOT      |  1100   |  0011  |
| Shift Left            |    -    | B-SHIFT-L  |  1101   |  1010  |
| Shift Left Circuar    |    -    | B-SHIFT-LC |  1101   |  1011  |
| Shift Right           |    -    | B-SHIFT-R  |  1101   |  0110  |
| Shift Right Circuar   |    -    | B-SHIFT-RC |  1101   |  1110  |
+-----------------------------------------------------------------+

      PS. Change also "Appendix C1 - Grouped Word Lists by feature and function"

      • Add 4 new operators B-SHIFT-L, B-SHIFT-LC, B-SHIFT-R and B-SHIFT-RC
      • Set Yes instead of No for all Boolean operators now supported.
       

  • Eugenio Di Lorenzo

    Eugenio Di Lorenzo - 2024-03-15

    I have prepared this test program.
    Please, could verify that the results (see screenshot) are correct ?

           >>SOURCE FORMAT IS FREE
IDENTIFICATION DIVISION.
PROGRAM-ID. TESTBOOLEAN.
DATA DIVISION.
WORKING-STORAGE SECTION.
01 A pic 9 comp-x value B'00000101'.
01 B pic 9 comp-x value B'00000011'.
01 c pic 9        value LOW-VALUE. 

PROCEDURE DIVISION.
  display space
  display '   a          b     c        a                 b          c    '
  display '  --- ------ ---   ---    -------- -------- --------   --------'
  display '   '  a  '  initial ' b '     ' c '     ' FUNCTION BIT-Of(a) ' initial  ' FUNCTION BIT-Of(b) '   ' FUNCTION BIT-OF(c)
  display space   display space
  display '   a operator b     c        a     operator    b          c    '
  display '  --- ------ ---   ---    -------- -------- --------   --------'
  compute c = a B-AND b 
  display '   '  a  '   AND    ' b '  =  ' c '     '  FUNCTION BIT-Of(a)  '   AND    ' FUNCTION BIT-Of(b) ' = ' FUNCTION BIT-OF(c)
  compute c = a B-OR b 
  display '   '  a  '   OR     ' b '  =  ' c '     '  FUNCTION BIT-Of(a)  '   OR     ' FUNCTION BIT-Of(b) ' = ' FUNCTION BIT-OF(c)
  compute c = a B-XOR b 
  display '   '  a  '   XOR    ' b '  =  ' c '     '  FUNCTION BIT-Of(a)  '   XOR    ' FUNCTION BIT-Of(b) ' = ' FUNCTION BIT-OF(c)
  compute c = B-NOT b 
  display '   -'    '   NOT    ' b '  =  ' c '         -   '              '   NOT    ' FUNCTION BIT-Of(b) ' = ' FUNCTION BIT-OF(c)

  accept omitted 
  STOP RUN.
     
    Thumbnail
    TESTBOOLEAN.png

  • Eugenio Di Lorenzo

    Eugenio Di Lorenzo - 2024-03-15

    Second test program for "SHIFT" operators.

    @Vincent: in the programmers guide you entered the B-SHIFT-xx operators as intrinsic functions. I believe this is incorrect.
    I ask Simon for confirmation.
    For example B-SHIFT-L is an "operator" like B-AND for example it is not an intrinsic function.

    The following program uses the B-SHIFT operators but I ask Simon if this example is correct.
    I believe that B-SHIFT operators should work like B-NOT i.e. with only one operand.
    However, if I put only one operand I get an error message from the compiler?!?!?
    By putting two operands with the B-SHIFT-L operator for example, I get a result that doesn't match.
    I think a clarification from Simon is needed.

           >>SOURCE FORMAT IS FREE
IDENTIFICATION DIVISION.
PROGRAM-ID. TESTBOOLEANSHIFT.
DATA DIVISION.
WORKING-STORAGE SECTION.
01 A pic 9 comp-x value B'00000001'.
01 B pic 9 comp-x value B'00000101'.
01 c pic 9        value LOW-VALUE.

PROCEDURE DIVISION.
  display space
  display '   a            b     c        a                   b          c    '
  display '  --- ------   ---   ---    -------- ---------- --------   --------'
  display '   '  a  '  initial   ' b '     ' c '     ' FUNCTION BIT-Of(a)   ' initial    ' FUNCTION BIT-Of(b) '   ' FUNCTION BIT-OF(c)
  display space   display space
  display '   a operator   b     c        a     operator      b          c    '
  display '  --- ------   ---   ---    -------- ---------- --------   --------'
  compute c = a B-SHIFT-L  b
  display '   '  a  ' B-SHIFT-L  ' b '  =  ' c '     '  FUNCTION BIT-Of(a)  ' B-SHIFT-L  ' FUNCTION BIT-Of(b) ' = ' FUNCTION BIT-OF(c)
  compute c = a B-SHIFT-LC b
  display '   '  a  ' B-SHIFT-LC ' b '  =  ' c '     '  FUNCTION BIT-Of(a)  ' B-SHIFT-LC ' FUNCTION BIT-Of(b) ' = ' FUNCTION BIT-OF(c)
  compute c = a B-SHIFT-R  b
  display '   '  a  ' B-SHIFT-R  ' b '  =  ' c '     '  FUNCTION BIT-Of(a)  ' B-SHIFT-R  ' FUNCTION BIT-Of(b) ' = ' FUNCTION BIT-OF(c)
  compute c = a B-SHIFT-RC b
  display '   '  a  ' B-SHIFT-RC ' b '  =  ' c '     '  FUNCTION BIT-Of(a)  ' B-SHIFT-RC ' FUNCTION BIT-Of(b) ' = ' FUNCTION BIT-OF(c)

  accept omitted
  STOP RUN.
     
    Thumbnail
    TESTBOOLEANSHIFT.png

  • Vincent (Bryan) Coen

    Vincent (Bryan) Coen - 2024-03-15

    So what is the state of the other four namely
    B-AND
    B-OR
    B-XOR
    B-NOT

    These are currently in under functions so I "assume" that they are wrong as well and should only be in 2.2.4 -ish and removed from 8. Correct ?
    .

     

    • Eugenio Di Lorenzo

      Eugenio Di Lorenzo - 2024-03-15

      There are no other boolean B-AND, B-OR ... in intrinsic functions chapter...
      They are all operators

      Please delete >> MORE text needed here? - PLACE HOLDER << and insert:

      Operands must be defined as PIC X(n) COMP-X or PIC 9(n) COMP-5.

       

      Last edit: Eugenio Di Lorenzo 2024-03-15
      Thumbnail
      PG.png

      • Vincent (Bryan) Coen

        Vincent (Bryan) Coen - 2024-03-15

        OK, its me mixing BIT-xxxx with B-xxx.

        Please ignore.

        On 15/03/2024 17:46, Eugenio Di Lorenzo wrote:

        There are no other boolean B-AND, B-OR ... in intrinsic functions...
        They are all operators

        Attachments:

         
        alternate

        • Eugenio Di Lorenzo

          Eugenio Di Lorenzo - 2024-03-16

          Ok thanks, now I think it's ok.

          A small correction: the syntax you wrote

          [ Operand-1 ] { Boolean-Operator } [ Operand-2 ]

          it should be :

          [ Operand-1 ] { Boolean-Operator } Operand-2

          as Operand-2 must always be present.
          Only Operand-1 can be missing when using the B-NOT operator which requires only Operand-2.

           

          • Simon Sobisch

            Simon Sobisch - 2024-03-16

            I'd suggest to specify a choice instead:

            operand-1 boolean-operator operand-2
B-NOT operand-3

            This way there are no optional operands and one does not have to make extra rules about B-NOT.

             
            alternate

  • Vincent (Bryan) Coen

    Vincent (Bryan) Coen - 2024-03-16

    Nag, nag, nag - it is all done - well until the next complaint :)

     

  • Vincent (Bryan) Coen

    Vincent (Bryan) Coen - 2024-06-12
    • status: open --> closed
    • assigned_to: Vincent (Bryan) Coen
     

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