/*
- * Copyright (c) 2008, 2009 Nicira Networks.
+ * Copyright (c) 2008, 2009, 2010, 2012, 2013 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.
*/
#ifndef HASH_H
#define HASH_H 1
+#include <stdbool.h>
#include <stddef.h>
#include <stdint.h>
#include <string.h>
+#include "util.h"
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+static inline uint32_t
+hash_rot(uint32_t x, int k)
+{
+ return (x << k) | (x >> (32 - k));
+}
-/* This is the public domain lookup3 hash by Bob Jenkins from
- * http://burtleburtle.net/bob/c/lookup3.c, modified for style. */
-
-#define HASH_ROT(x, k) (((x) << (k)) | ((x) >> (32 - (k))))
-
-#define HASH_MIX(a, b, c) \
- do { \
- a -= c; a ^= HASH_ROT(c, 4); c += b; \
- b -= a; b ^= HASH_ROT(a, 6); a += c; \
- c -= b; c ^= HASH_ROT(b, 8); b += a; \
- a -= c; a ^= HASH_ROT(c, 16); c += b; \
- b -= a; b ^= HASH_ROT(a, 19); a += c; \
- c -= b; c ^= HASH_ROT(b, 4); b += a; \
- } while (0)
-
-#define HASH_FINAL(a, b, c) \
- do { \
- c ^= b; c -= HASH_ROT(b, 14); \
- a ^= c; a -= HASH_ROT(c, 11); \
- b ^= a; b -= HASH_ROT(a, 25); \
- c ^= b; c -= HASH_ROT(b, 16); \
- a ^= c; a -= HASH_ROT(c, 4); \
- b ^= a; b -= HASH_ROT(a, 14); \
- c ^= b; c -= HASH_ROT(b, 24); \
- } while (0)
-
-uint32_t hash_words(const uint32_t *, size_t n_word, uint32_t basis);
+uint32_t hash_words(const uint32_t data[], size_t n_words, uint32_t basis);
uint32_t hash_bytes(const void *, size_t n_bytes, uint32_t basis);
+static inline uint32_t hash_int(uint32_t x, uint32_t basis);
+static inline uint32_t hash_2words(uint32_t, uint32_t);
+static inline uint32_t hash_uint64(uint64_t);
+static inline uint32_t hash_uint64_basis(uint64_t x, uint32_t basis);
+uint32_t hash_3words(uint32_t, uint32_t, uint32_t);
+
+static inline uint32_t hash_boolean(bool x, uint32_t basis);
+uint32_t hash_double(double, uint32_t basis);
+
+static inline uint32_t hash_pointer(const void *, uint32_t basis);
+static inline uint32_t hash_string(const char *, uint32_t basis);
+
+/* Murmurhash by Austin Appleby,
+ * from http://code.google.com/p/smhasher/source/browse/trunk/MurmurHash3.cpp.
+ *
+ * The upstream license there says:
+ *
+ * // MurmurHash3 was written by Austin Appleby, and is placed in the public
+ * // domain. The author hereby disclaims copyright to this source code.
+ *
+ * See hash_words() for sample usage. */
+
+static inline uint32_t mhash_add__(uint32_t hash, uint32_t data)
+{
+ data *= 0xcc9e2d51;
+ data = hash_rot(data, 15);
+ data *= 0x1b873593;
+ return hash ^ data;
+}
+
+static inline uint32_t mhash_add(uint32_t hash, uint32_t data)
+{
+ hash = mhash_add__(hash, data);
+ hash = hash_rot(hash, 13);
+ return hash * 5 + 0xe6546b64;
+}
+
+static inline uint32_t mhash_finish(uint32_t hash, size_t n_bytes)
+{
+ hash ^= n_bytes;
+ hash ^= hash >> 16;
+ hash *= 0x85ebca6b;
+ hash ^= hash >> 13;
+ hash *= 0xc2b2ae35;
+ hash ^= hash >> 16;
+ return hash;
+}
+
static inline uint32_t hash_string(const char *s, uint32_t basis)
{
return hash_bytes(s, strlen(s), basis);
}
-/* This is Bob Jenkins' integer hash from
- * http://burtleburtle.net/bob/hash/integer.html, modified for style. */
static inline uint32_t hash_int(uint32_t x, uint32_t basis)
{
- x -= x << 6;
- x ^= x >> 17;
- x -= x << 9;
- x ^= x << 4;
- x -= x << 3;
- x ^= x << 10;
- x ^= x >> 15;
- return x + basis;
+ return hash_2words(x, basis);
+}
+
+/* An attempt at a useful 1-bit hash function. Has not been analyzed for
+ * quality. */
+static inline uint32_t hash_boolean(bool x, uint32_t basis)
+{
+ const uint32_t P0 = 0xc2b73583; /* This is hash_int(1, 0). */
+ const uint32_t P1 = 0xe90f1258; /* This is hash_int(2, 0). */
+ return (x ? P0 : P1) ^ hash_rot(basis, 1);
+}
+
+static inline uint32_t hash_pointer(const void *p, uint32_t basis)
+{
+ /* Often pointers are hashed simply by casting to integer type, but that
+ * has pitfalls since the lower bits of a pointer are often all 0 for
+ * alignment reasons. It's hard to guess where the entropy really is, so
+ * we give up here and just use a high-quality hash function.
+ *
+ * The double cast suppresses a warning on 64-bit systems about casting to
+ * an integer to different size. That's OK in this case, since most of the
+ * entropy in the pointer is almost certainly in the lower 32 bits. */
+ return hash_int((uint32_t) (uintptr_t) p, basis);
+}
+
+static inline uint32_t hash_2words(uint32_t x, uint32_t y)
+{
+ return mhash_finish(mhash_add(mhash_add(x, 0), y), 8);
+}
+
+static inline uint32_t hash_uint64(const uint64_t x)
+{
+ return hash_2words((uint32_t)(x >> 32), (uint32_t)x);
+}
+
+static inline uint32_t hash_uint64_basis(const uint64_t x,
+ const uint32_t basis)
+{
+ return hash_3words((uint32_t)(x >> 32), (uint32_t)x, basis);
+}
+#ifdef __cplusplus
}
+#endif
#endif /* hash.h */
git://git.onelab.eu / sliver-openvswitch.git / blobdiff