X-Git-Url: http://www.chiark.greenend.org.uk/ucgi/~ian/git?p=moebius2.git;a=blobdiff_plain;f=mgraph.c;h=46c7533827b1445c2498773106301e2898a94f47;hp=7f5f3bd2c06facf29d9b6ec2af6f7663f8aee4cd;hb=fcb05a81ecead2dcd3375c6d4ceb528ca6e181c0;hpb=75293637fe7efbce3f2e873cc792da3bff577fef

diff --git a/mgraph.c b/mgraph.c
index 7f5f3bd..46c7533 100644
--- a/mgraph.c
+++ b/mgraph.c
@@ -39,3 +39,10 @@ int edge_reverse(int v1, int e) {
 //	 v1,e,eprime, EDGE_END2(v1,e), x2,flip);
   return eprime;
 }
+
+int vertices_span_join_p(int v0, int v1) {
+  int v0x= v0 & XMASK;
+  int v1x= v1 & XMASK;
+  int diff= v0x-v1x;
+  return diff < -2 || diff > 2;
+}