+/* bitwise-ands maps t and s, stores the result in t. */
+void
+map_and(Map *t, Map *s)
+{
+ unsigned char *ti, *si, *end;
+ ti = t->map;
+ si = s->map;
+ end = ti + (t->size < s->size ? t->size : s->size);
+ while (ti < end)
+ *ti++ &= *si++;
+}
+
+/* bitwise-ors maps t and s, stores the result in t. */
+void
+map_or(Map *t, Map *s)
+{
+ unsigned char *ti, *si, *end;
+ if (t->size < s->size)
+ map_grow(t, s->size << 3);
+ ti = t->map;
+ si = s->map;
+ end = ti + (t->size < s->size ? t->size : s->size);
+ while (ti < end)
+ *ti++ |= *si++;
+}
+
+/* remove all set bits in s from t. */
+void
+map_subtract(Map *t, Map *s)
+{
+ unsigned char *ti, *si, *end;
+ ti = t->map;
+ si = s->map;
+ end = ti + (t->size < s->size ? t->size : s->size);
+ while (ti < end)
+ *ti++ &= ~*si++;
+}
+
+void
+map_invertall(Map *m)
+{
+ unsigned char *ti, *end;
+ ti = m->map;
+ end = ti + m->size;
+ while (ti < end)
+ *ti++ ^= 0xff;
+}
+