Experimental Physics and
Industrial Control System

[email protected] (Nick Rees) · Mon, 1 Apr 96 08:48:47 HST

Andy Foster wrote:

> Has anyone successfully used CALCULATION records with
> capfast 3.02.23?
> 
> I found the following:
> 
> B=0?1:A  was rejected with "missing question mark in conditional expression"
> A%6      was rejected with "Illegal Operand"
> B*(A+1)  was rejected with "Illegal Operand"
> 
> In my opinion, this makes this version of Capfast unusable with CALC records.
> 
> Are these known bugs which have been fixed or are there **really** 
> syntax errors in the above expressions?
> 
> If they have been fixed, please can I get hold of a working version.

Appended is the comments about the checking of the CALC field syntax for
EPICS applications that was in the release notes. To avoid the problems
put the following in your ~/schedit.rc

:set checkEPICSexprs NO

I have tested your expressions in my version (3.02.25) and found the
same problems, but according to the release note they are legal. I will
let the guys at Phase 3 know about it. I feel they have gone a bit over
the top in all this - they have reinvented our RPN parser. What would
have been more sensible would have been to use our parser to check the
validity of the expression.

Can someone tell me how we could and if we could let Phase 3 have a copy
of postfix.c? I know this would probably involve lawyers, but since
it is purely for the benefit of the Epics community, then maybe there
may be a workaround.

Nick Rees

Joint Astronomy Centre                    Ph:       +1 (808) 961-3756
660 N. Aohoku Place                       Fax:      +1 (808) 961-6516
Hilo, HI.  96720                          Internet: [email protected]

--- The following is from the Capfast release notes ---------------------

X.    Reserved use of CALC for EPICS applications

      When the internal variable, checkEPICSexprs, has been set to YES,
      the property rules editor reserves the property name, CALC, for
      arithmetic or logical expressions that use only certain legal
      operands (defined as any single character A through L and RNDM)
      and the following legal operators:

      Alg.                                     Trig.
      operator   Meaning                        operators   Meaning
      --------   -------                        ---------   -------
      ABS        Absolute value (unary)         SIN         Sine
      SQR        Square root (unary)            SINH        Hyperbolic sine
      MIN        Minimum (binary function)      ASIN        Arc sine
      MAX        Maximum (binary function)      COS         Cosine
      CEIL       Ceiling (unary)                COSH        Hyperbolic cosin
      FLOOR      Floor (unary)                  ACOS        Arc cosine
      LOG        Log base 10 (unary)            TAN         Tangent
      LOGE       Natural log (unary)            TANH        Hyperbolic tange
      EXP        Exponential function (unary)   ATAN        Arc tangent
      ^          Exponential (binary)
      **         Exponential (binary)
      +          Addition (binary)              Relational
      -          Subtraction (binary)           Operators
      *          Multiplication (binary)        ----------
      /          Division (ginary)              <,>,<=,>=   As prev. defined
      %          Modulo (binary)                =           Equal to
      NOT        Negate (binary)                #           Not equal to

      Logical                                   Bitwise
      Operators                                 Operators
      ---------                                 ---------
       &&         And                           |           Bitwise Or
       ||         Or                            &           Bitwise And
       !          Not                           OR          Bitwise Or
                                                AND         Bitwise And
                                                XOR         Bitwise Excl. Or
                                                -           One's Complement
                                                <<          Left shift
                                                >>          Right shift

      Open and closed parenthesis, and nested parenthesis are allowed.
      Commas may only be used to separate the arguments of a binary function.
      The editor will allow the "C" question mark operator in the following
           format:
                    (condition)? True result : False result

      SAMPLE expressions for reserved use of CALC:

      Expression            Result
      ----------            ------
      A + B                 A + B

      (A | B) < (C + D)     1 if (A+B)<(C+D)
                            0 if (A+B)>=(C+D)

      (A+B)<(C+D)?E:F       E if (A+B)<(C+D)
                            F if (A+B)>=(C+D)

      (A+B)<(C+D)?E         E if (A+B)<(C+D)
                            unchanged if (A+B)>=(C+D)

      A&B                   converts A to integer, converts B to integer,
                            bit-wise And A and B, convert result to floating
                            point  

Experimental Physics and Industrial Control System

Experimental Physics and
Industrial Control System