switch (size-firstindex) {  case 1:    hash= (ptr_intT)(*elemp) - (ptr_intT) skipelem;    break;  case 2:    hash= (ptr_intT)(*elemp) + (ptr_intT)elemp[1] - (ptr_intT) skipelem;    break;  case 3:    hash= (ptr_intT)(*elemp) + (ptr_intT)elemp[1] + (ptr_intT)elemp[2]      - (ptr_intT) skipelem;    break;  case 4:    hash= (ptr_intT)(*elemp) + (ptr_intT)elemp[1] + (ptr_intT)elemp[2]      + (ptr_intT)elemp[3] - (ptr_intT) skipelem;    break;  case 5:    hash= (ptr_intT)(*elemp) + (ptr_intT)elemp[1] + (ptr_intT)elemp[2]      + (ptr_intT)elemp[3] + (ptr_intT)elemp[4] - (ptr_intT) skipelem;    break;  case 6:    hash= (ptr_intT)(*elemp) + (ptr_intT)elemp[1] + (ptr_intT)elemp[2]      + (ptr_intT)elemp[3] + (ptr_intT)elemp[4]+ (ptr_intT)elemp[5]      - (ptr_intT) skipelem;    break;  default:    hash= 0;    i= 3;    do {     /* this is about 10% in 10-d */      if ((elem= (ptr_intT)*elemp++) != (ptr_intT)skipelem) {        hash ^= (elem << i) + (elem >> (32-i));	i += 3;	if (i >= 32)	  i -= 32;      }    }while(*elemp);    break;  }  hash %= (ptr_intT) hashsize;  /* hash= 0;   for debugging purposes */  return hash;} /* gethash *//*--------------------------------------------------makenewfacet- creates a toporient? facet from vertices and apex   modifies vertices returns:    adds newfacet to qh facet_list        facet->neighbor= horizon, but not vice versa    facet->vertices= vertices= apex+vertices    newvertex_list updated*/facetT *qh_makenewfacet(setT *vertices, boolT toporient,facetT *horizon) {  facetT *newfacet;  vertexT *vertex, **vertexp;  FOREACHvertex_(vertices) {    if (!vertex->newlist) {      qh_removevertex (vertex);      qh_appendvertex (vertex);    }  }  newfacet= qh_newfacet();  newfacet->vertices= vertices;  newfacet->toporient= toporient;  qh_setappend(&(newfacet->neighbors), horizon);  qh_appendfacet(newfacet);  return(newfacet);} /* makenewfacet *//*---------------------------------------------makenewplanes- make new hyperplanes for facets  ->f.samecycle defined for ->mergehorizon facetsreturns:  all facets have hyperplanes or are marked for merging    doesn't create plane if horizon is coplanar (will merge)*/void qh_makenewplanes (void /* newfacet_list */) {  facetT *newfacet;  FORALLnew_facets {    if (!newfacet->mergehorizon)      qh_setfacetplane (newfacet);    }} /* makenewplanes *//*----------------------------------------------makenew_nonsimplicial- make new facets for ridges of visible facets  qh visit_id if visible has already been seen  attaches new facets if !qh ONLY good  assumes all 'seen' flags falsereturns:  newfacet or NULL, bumps numnew as needed  marks ridge neighbors for simplicial visible  if (qh ONLYgood)    ridges on newfacet, horizon, and visible  else    ridge and neighbors between newfacet and horizon    visible facet's ridges are deleted    */#ifndef qh_NOmergefacetT *qh_makenew_nonsimplicial (facetT *visible, vertexT *apex, int *numnew) {  void **freelistp;  ridgeT *ridge, **ridgep;  facetT *neighbor, *newfacet= NULL, *samecycle;  setT *vertices;  boolT toporient;  FOREACHridge_(visible->ridges) {    neighbor= otherfacet_(ridge, visible);    if (neighbor->visible) {      if (!qh ONLYgood) {        if (neighbor->visitid == qh visit_id) {          qh_setfree (&(ridge->vertices));  /* delete on 2nd visit */	  qh_memfree_(ridge, sizeof(ridgeT), freelistp);	}      }    }else {  /* neighbor is an horizon facet */      toporient= (ridge->top == visible);      vertices= qh_setnew (qh hull_dim); /* makes sure this is quick */      qh_setappend (&vertices, apex);      qh_setappend_set (&vertices, ridge->vertices);      newfacet= qh_makenewfacet(vertices, toporient, neighbor);      (*numnew)++;      if (neighbor->coplanar) {	newfacet->mergehorizon= True;        if (!neighbor->seen) {          newfacet->f.samecycle= newfacet;          neighbor->f.newcycle= newfacet;        }else {          samecycle= neighbor->f.newcycle;          newfacet->f.samecycle= samecycle->f.samecycle;          samecycle->f.samecycle= newfacet;	}      }      if (qh ONLYgood) {        if (!neighbor->simplicial) 	  qh_setappend(&(newfacet->ridges), ridge);      }else {  /* qh_attachnewfacets */        if (neighbor->seen) {	  if (neighbor->simplicial) {	    fprintf (qh ferr, "qhull internal error (qh_makenew_nonsimplicial): simplicial f%d sharing two ridges with f%d\n", 	           neighbor->id, visible->id);	    qh_errexit2 (qh_ERRqhull, neighbor, visible);	  }	  qh_setappend (&(neighbor->neighbors), newfacet);	}else          qh_setreplace (neighbor->neighbors, visible, newfacet);        if (neighbor->simplicial) {          qh_setdel (neighbor->ridges, ridge);          qh_setfree (&(ridge->vertices)); 	  qh_memfree (ridge, sizeof(ridgeT));	}else { 	  qh_setappend(&(newfacet->ridges), ridge); 	  if (toporient) 	    ridge->top= newfacet; 	  else 	    ridge->bottom= newfacet; 	}      trace4((qh ferr, "qh_makenew_nonsimplicial: created facet f%d from v%d and r%d of horizon f%d\n",	    newfacet->id, apex->id, ridge->id, neighbor->id));      }    }    neighbor->seen= True;          } /* for each ridge */  if (!qh ONLYgood)    SETfirst_(visible->ridges)= NULL;  return newfacet;} /* makenew_nonsimplicial */#else /* qh_NOmerge */facetT *qh_makenew_nonsimplicial (facetT *visible, vertexT *apex, int *numnew) {  return NULL;}#endif /* qh_NOmerge *//*----------------------------------------------makenew_simplicial- make new facets for simplicial facet  nop if neighbor->seen or neighbor->visible (see makenew_nonsimplicial)  attaches new facets if !qh ONLY goodreturns:  newfacet or NULL, bumps numnew as needed  if (!qh ONLYgood)    neighbors between newfacet and horizon*/facetT *qh_makenew_simplicial (facetT *visible, vertexT *apex, int *numnew) {  facetT *neighbor, **neighborp, *newfacet= NULL;  setT *vertices;  boolT flip, toporient;  int horizonskip, visibleskip;  FOREACHneighbor_(visible) {    if (!neighbor->seen && !neighbor->visible) {      vertices= qh_facetintersect(neighbor,visible, &horizonskip, &visibleskip, 1);      SETfirst_(vertices)= apex;      flip= ((horizonskip & 0x1) ^ (visibleskip & 0x1));      if (neighbor->toporient)         	toporient= horizonskip & 0x1;      else	toporient= (horizonskip & 0x1) ^ 0x1;      newfacet= qh_makenewfacet(vertices, toporient, neighbor);      (*numnew)++;      if (neighbor->coplanar && (qh PREmerge || qh MERGEexact)) {#ifndef qh_NOmerge	newfacet->f.samecycle= newfacet;	newfacet->mergehorizon= True;#endif      }      if (!qh ONLYgood)        SETelem_(neighbor->neighbors, horizonskip)= newfacet;      trace4((qh ferr, "qh_makenew_simplicial: create facet f%d top %d from v%d and horizon f%d skip %d top %d and visible f%d skip %d, flip? %d\n",	    newfacet->id, toporient, apex->id, neighbor->id, horizonskip,	      neighbor->toporient, visible->id, visibleskip, flip));    }  }  return newfacet;} /* makenew_simplicial *//*--------------------------------------------------matchneighbor- match subridge of newfacet with neighbor or add to hash_table  ridge is newfacet->vertices w/o newskip vertexreturns:  duplicate ridges are unmatched and marked by qh_DUPLICATEridgenotes:  do not allocate memory (need to free hash_table cleanly)  similar to matchduplicates  uses linear hash chains*/void qh_matchneighbor (facetT *newfacet, int newskip, int hashsize, int *hashcount) {  boolT newfound= False;   /* True, if new facet is already in hash chain */  boolT same, ismatch;  unsigned hash, scan;  facetT *facet, *matchfacet;  int skip, matchskip;  hash= qh_gethash (hashsize, newfacet->vertices, qh hull_dim, 1,                      SETelem_(newfacet->vertices, newskip));  trace4((qh ferr, "qh_matchneighbor: newfacet f%d skip %d hash %d hashcount %d\n",	  newfacet->id, newskip, hash, *hashcount));  zinc_(Zhashlookup);  for (scan= hash; (facet= SETelem_(qh hash_table, scan));        scan= (++scan >= hashsize ? 0 : scan)) {    if (facet == newfacet) {      newfound= True;      continue;    }    zinc_(Zhashtests);    if (qh_matchvertices (1, newfacet->vertices, newskip, facet->vertices, &skip, &same)) {      if (SETelem_(newfacet->vertices, newskip) ==           SETelem_(facet->vertices, skip)) {        fprintf (qh ferr, "qhull precision error: Vertex sets are the same for f%d and f%d.  Can not force output.\n",          facet->id, newfacet->id);        qh_errexit2 (qh_ERRprec, facet, newfacet);      }      ismatch= (same == (newfacet->toporient ^ facet->toporient));      matchfacet= SETelem_(facet->neighbors, skip);      if (ismatch && !matchfacet) {        SETelem_(facet->neighbors, skip)= newfacet;        SETelem_(newfacet->neighbors, newskip)= facet;        (*hashcount)--;        trace4((qh ferr, "qh_matchneighbor: f%d skip %d matched with new f%d skip %d\n",           facet->id, skip, newfacet->id, newskip));        return;      }      if (!qh PREmerge && !qh MERGEexact) {	fprintf (qh ferr, "qhull precision error: facets f%d, f%d and f%d meet at a ridge with more than 2 neighbors.  Can not continue.\n",		 facet->id, newfacet->id, getid_(matchfacet));	qh_errexit2 (qh_ERRprec, facet, newfacet);      }      SETelem_(newfacet->neighbors, newskip)= qh_DUPLICATEridge;      newfacet->dupridge= True;      if (!newfacet->normal)	qh_setfacetplane (newfacet);      qh_addhash (newfacet, qh hash_table, hashsize, hash);      (*hashcount)++;      if (!facet->normal)	qh_setfacetplane (facet);      if (matchfacet != qh_DUPLICATEridge) {	SETelem_(facet->neighbors, skip)= qh_DUPLICATEridge;	facet->dupridge= True;	if (!facet->normal)	  qh_setfacetplane (facet);	if (matchfacet) {	  matchskip= qh_setindex (matchfacet->neighbors, facet);	  SETelem_(matchfacet->neighbors, matchskip)= qh_DUPLICATEridge;	  matchfacet->dupridge= True;	  if (!matchfacet->normal)	    qh_setfacetplane (matchfacet);	  qh_addhash (matchfacet, qh hash_table, hashsize, hash);	  *hashcount += 2;	}      }      trace4((qh ferr, "qh_matchneighbor: new f%d skip %d duplicates ridge for f%d skip %d matching f%d ismatch %d at hash %d\n",	   newfacet->id, newskip, facet->id, skip, 	   (matchfacet == qh_DUPLICATEridge ? -2 : getid_(matchfacet)), 	   ismatch, hash));      return; /* end of duplicate ridge */    }  }  if (!newfound)     SETelem_(qh hash_table, scan)= newfacet;  /* same as qh_addhash */  (*hashcount)++;  trace4((qh ferr, "qh_matchneighbor: no match for f%d skip %d at hash %d\n",           newfacet->id, newskip, hash));} /* matchneighbor *//*--------------------------------------------------matchnewfacets- match newfacets in newfacet_list to their newfacet neighbors  newfacets already have neighbor[0] (horizon facet)  assumes qh hash_table is NULL  vertex->neighbors has not been updated yetreturns:  qh newfacet_list with full neighbor sets