X-Git-Url: https://pintos-os.org/cgi-bin/gitweb.cgi?a=blobdiff_plain;f=lib%2Ftag.c;h=f064d17867f485900684ad013e495a4ab02d61ed;hb=c2725b60074755713b2fdd73559b6d24d5eb7970;hp=8a4ee8925484aab5aebee4116a93dc4723fb1b7a;hpb=064af42167bf4fc9aaea2702d80ce08074b889c0;p=openvswitch

diff --git a/lib/tag.c b/lib/tag.c
index 8a4ee892..f064d178 100644
--- a/lib/tag.c
+++ b/lib/tag.c
@@ -1,17 +1,17 @@
 /*
- * Copyright (c) 2008, 2009 Nicira Networks.
+ * Copyright (c) 2008, 2009, 2010, 2011 Nicira, Inc.
  *
- * Permission to use, copy, modify, and/or distribute this software for any
- * purpose with or without fee is hereby granted, provided that the above
- * copyright notice and this permission notice appear in all copies.
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at:
  *
- * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
- * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
- * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
- * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
- * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
- * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
- * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
  */
 
 #include <config.h>
@@ -49,7 +49,7 @@ tag_type
 tag_create_deterministic(uint32_t seed)
 {
     int x = seed & (N_TAG_BITS - 1);
-    int y = (seed >> LOG2_N_TAG_BITS) % 31;
+    int y = (seed >> LOG2_N_TAG_BITS) % (N_TAG_BITS - 1);
     y += y >= x;
     return (1u << x) | (1u << y);
 }
@@ -61,11 +61,36 @@ tag_set_init(struct tag_set *set)
     memset(set, 0, sizeof *set);
 }
 
+static bool
+tag_is_worth_adding(const struct tag_set *set, tag_type tag)
+{
+    if (!tag) {
+        /* Nothing to add. */
+        return false;
+    } else if ((set->total & tag) != tag) {
+        /* 'set' doesn't have all the bits in 'tag', so we need to add it. */
+        return true;
+    } else {
+        /* We can drop it if some member of 'set' already includes all of the
+         * 1-bits in 'tag'.  (tag_set_intersects() does a different test:
+         * whether some member of 'set' has at least two 1-bit in common with
+         * 'tag'.) */
+        int i;
+
+        for (i = 0; i < TAG_SET_SIZE; i++) {
+            if ((set->tags[i] & tag) == tag) {
+                return false;
+            }
+        }
+        return true;
+    }
+}
+
 /* Adds 'tag' to 'set'. */
 void
 tag_set_add(struct tag_set *set, tag_type tag)
 {
-    if (tag && (!tag_is_valid(tag) || !tag_set_intersects(set, tag))) {
+    if (tag_is_worth_adding(set, tag)) {
         /* XXX We could do better by finding the set member to which we would
          * add the fewest number of 1-bits.  This would reduce the amount of
          * ambiguity, since e.g. three 1-bits match 3 * 2 / 2 = 3 unique tags
@@ -80,3 +105,13 @@ tag_set_add(struct tag_set *set, tag_type tag)
     }
 }
 
+/* Adds all the tags in 'other' to 'set'. */
+void
+tag_set_union(struct tag_set *set, const struct tag_set *other)
+{
+    size_t i;
+
+    for (i = 0; i < TAG_SET_SIZE; i++) {
+        tag_set_add(set, other->tags[i]);
+    }
+}