/*
- * Copyright (c) 2008, 2009, 2010 Nicira Networks.
+ * Copyright (c) 2008, 2009, 2010, 2012 Nicira, Inc.
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
#include <string.h>
#include "util.h"
+#ifdef __cplusplus
+extern "C" {
+#endif
+
/* 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)
+static inline uint32_t
+hash_rot(uint32_t x, int k)
+{
+ return (x << k) | (x >> (32 - k));
+}
+
+static inline void
+hash_mix(uint32_t *a, uint32_t *b, uint32_t *c)
+{
+ *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;
+}
+
+static inline void
+hash_final(uint32_t *a, uint32_t *b, uint32_t *c)
+{
+ *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);
+}
uint32_t hash_words(const uint32_t *, size_t n_word, uint32_t basis);
uint32_t hash_2words(uint32_t, uint32_t);
* quality. */
static inline uint32_t hash_boolean(bool x, uint32_t basis)
{
- enum { P0 = 0xc2b73583 }; /* This is hash_int(1, 0). */
- enum { P1 = 0xe90f1258 }; /* This is hash_int(2, 0). */
- return (x ? P0 : P1) ^ HASH_ROT(basis, 1);
+ 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_double(double x, uint32_t basis)
return hash_int((uint32_t) (uintptr_t) p, 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.
+ *
+ * Murmurhash is faster and higher-quality than the Jenkins lookup3 hash. When
+ * we have a little more familiarity with it, it's probably a good idea to
+ * switch all of OVS to it.
+ *
+ * For now, we have this implementation here for use by code that needs a hash
+ * that is convenient for use one word at a time, since the Jenkins lookup3
+ * hash works three words at a time.
+ *
+ * See mhash_words() for sample usage. */
+
+uint32_t mhash_words(const uint32_t data[], size_t n_words, uint32_t basis);
+
+static inline uint32_t mhash_add(uint32_t hash, uint32_t data)
+{
+ data *= 0xcc9e2d51;
+ data = hash_rot(data, 15);
+ data *= 0x1b873593;
+
+ hash ^= data;
+ hash = hash_rot(hash, 13);
+ return hash * 5 + 0xe6546b64;
+}
+
+static inline uint32_t mhash_finish(uint32_t hash, size_t n)
+{
+ hash ^= n * 4;
+ hash ^= hash_rot(hash, 16);
+ hash *= 0x85ebca6b;
+ hash ^= hash_rot(hash, 13);
+ hash *= 0xc2b2ae35;
+ hash ^= hash_rot(hash, 16);
+ return hash;
+}
+
+#ifdef __cplusplus
+}
+#endif
+
#endif /* hash.h */