[rrd-users] CDEF,RPN, no decimal constant possible?

Tobias Oetiker tobi at oetiker.ch
Fri Jul 11 14:17:11 CEST 2014

Hi Steve,

the reason for this is, that the space for storing COMPUTE
instructions is rather limited. things to observe when patching

a) backward compatibility
b) space constraints

maybe an option would be to just throw an error when someone tries
to put a non integer number into a compute rule


Today Steve Shipway wrote:

> >[constants in the RPN are stored in doubles, but COMPUTE type DS convert using...]
> >
> >typedef struct rpn_cdefds_t {
> >    char      op;       /* rpn operator type */
> >    short     val;      /* used by OP_NUMBER and OP_VARIABLE */
> >} rpn_cdefds_t;
> >
> >Now val is only a short int.
> Well spotted!  I saw the first struct used doubles, but didn't dig deeply enough to spot this one.
> I would say this is a bug; however, there might be a reason for it, if Tobi can tell us?
> Otherwise, it should probably be a double and not a short -- making a patch for rrdtool should be simple.
> Steve
> Steve Shipway
> University of Auckland ITS
> UNIX Systems Design Lead
> s.shipway at auckland.ac.nz
> Ph: +64 9 373 7599 ext 86487

Tobi Oetiker, OETIKER+PARTNER AG, Aarweg 15 CH-4600 Olten, Switzerland
www.oetiker.ch tobi at oetiker.ch +41 62 775 9902

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