🚀 go-pugleaf

In article <ogcvax.1351> I write:
>In article <hubcap.282> gdburns@TCGOULD.TN.CORNELL.EDU (Greg Burns) writes:
>>000 001 011 010 110 111 101 100
>>
>>Given only a bit code difference (src exclusive or dest) we all know how
>>to route on a hypercube.  But how do you determine the route on the above
>>loop?
>
>  . . .
>
>Any solution that doesn't require message passing will beat this
>for setup speed, but I don't know about simplicity.

Message passing can be eliminated easily by just "simulating" the
cube on each node.  This can be done by using something like the
following:  (Unlike the previous alg, this one is untested though
nearly identical)
   dest = 0;
   count = 0;
   do {
     ++count;
     me = dest;
     dest = me ^ (count & -count);
   } while (me != mynode)
   if (count == cubesize) dest = 0;
   /* dest now contains ptr to next guy in the ring */

The previous algorithm is missing the special-case "if" at the end.

Sorry for wasting so much bandwidth on a personal solution to a
problem which has likely been solved by uncountable others (and
probably better).
-- 
Dave DiNucci                    UUCP:  ..ucbvax!tektronix!ogcvax!dinucci
Oregon Graduate Center          CSNET: dinucci@Oregon-Grad.csnet
Beaverton, Oregon