[rrd-developers] ROL and ROR for RPN

[Tobias Oetiker]

Hi Steve,

Today Steve Shipway wrote:

> In that case, maybe just call it ROTATE.  This would give the maximum flexibility..
>
> x1, x2 .... xn, n, steps, ROTATE
> where
> n > 0
> 0 < abs(steps) < n
>
> I'm trying to think of an efficient way to do this that doesn't
> involve a malloc (it's easy if you can malloc(n*sizeof(double*))
> ).  Will have a go when I'm in the office tomorrow.
>
> However should we keep ROL and ROR as shorthand for the more
> common 3,1,ROTATE and 3,-1,ROTATE ?

as the other poster said, it might be a good thing to take
inspiration from postscript ...

if you think the ROL and ROR variantes make peoples lives easier, I
have no problem with adding them as well

cheers
tobi

> Steve
>
> Steve Shipway
> University of Auckland ITS
> UNIX Systems Design Lead
> s.shipway at auckland.ac.nz
> Ph: +64 9 373 7599 ext 86487
>
>
> ________________________________________
> From: Tobias Oetiker [tobi at oetiker.ch]
> Sent: Monday, 28 April 2014 6:30 p.m.
> To: Steve Shipway
> Cc: rrd-developers at lists.oetiker.ch
> Subject: Re: [rrd-developers] ROL and ROR for RPN
>
> Hi Steve,
>
> your function always affects 3 values ... would there be any gain
> in makeing this call more generic ?
>
> a,b,c,d,x,y,ROL rotate the last x values on the stack by y steps to
> the left. and maybe have -y role to the right?
>
> cheers
> tobi
>
>

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