#define Y1 (1 << YSHIFT)
#define V6 6
+#define V3 3
#define FOR_VERTEX(v) \
for ((v)=0; (v)<N; (v)++)
* returns eprime s.t. v1==EDGE_END2(v2,eprime) */
int edge_reverse(int v1, int e);
+#define EDGE_OPPOSITE(e) (((e)+V3) % V6)
+
#define RIM_VERTEX_P(v) (((v) & ~XMASK) == 0 || ((v) & ~XMASK) == (Y-1)*Y1)
#define FOR_VEDGE_X(v1,e,v2,init,otherwise) \