BI_MpathBR.c

Go to the documentation of this file.

#include "Bdef.h"
 
void BI_MpathBR(BLACSCONTEXT *ctxt, BLACBUFF *bp, SDRVPTR send, int src, int npaths)
{
   void BI_Arecv(BLACSCONTEXT *, int, int, BLACBUFF *);
   int BI_BuffIsFree(BLACBUFF *, int);
 
   int pathlen;     /* the minimal length of each path */
   int mydist;      /* my distance from src */
   int faredge;     /* node at far end of path */
   int lastlong;    /* distance to node on end of last path with extra node */
   int Np, Iam, msgid, Np_1, dest;
 
   msgid = Mscopeid(ctxt);
   BI_Arecv(ctxt, BANYNODE, msgid, bp);
   Np = ctxt->scp->Np;
   Iam = ctxt->scp->Iam;
   Np_1 = Np - 1;
   if (npaths == FULLCON) npaths = Np_1;
 
   if (npaths > 0)
   {
      dest = (Iam+1) % Np;
      mydist = (Np + Iam - src) % Np;
   }
   else
   {
      dest = (Np_1+Iam) % Np;
      mydist = (Np + src - Iam) % Np;
      npaths = -npaths;
   }
/*
 * Make sure npaths is cool
 */
   if (npaths > Np_1) npaths = Np_1;
 
   pathlen = Np_1 / npaths;
   lastlong = (Np_1%npaths) * (pathlen+1);
   if (lastlong)
   {
      if (mydist <= lastlong) faredge = ((mydist-1)/(pathlen+1)+1)*(pathlen+1);
      else faredge = ((lastlong-1)/(pathlen+1)+1) * (pathlen+1)
             + ((mydist-lastlong-1)/pathlen + 1) * pathlen;
   }
   else faredge = ((mydist-1)/pathlen + 1) * pathlen;
 
   BI_BuffIsFree(bp, 1);    /* wait for recv to complete */
   if (mydist < faredge) send(ctxt, dest, msgid, bp);
}