X-Git-Url: https://pintos-os.org/cgi-bin/gitweb.cgi?a=blobdiff_plain;f=lib%2Fhash.h;h=701e6866eec441ac1ddda491208cee4bc8b57ed8;hb=e879d33e8398219d5c9af8fd565c97303f126809;hp=109612fb760fe4d93e21c7ad091b41fd29b2f764;hpb=1f26e79678c9601477c072021598d4d1f5abfb43;p=openvswitch

diff --git a/lib/hash.h b/lib/hash.h
index 109612fb..701e6866 100644
--- a/lib/hash.h
+++ b/lib/hash.h
@@ -1,5 +1,5 @@
 /*
- * 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.
@@ -22,31 +22,41 @@
 #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);
@@ -81,9 +91,9 @@ static inline uint32_t hash_int(uint32_t x, uint32_t basis)
  * 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)
@@ -108,4 +118,50 @@ static inline uint32_t hash_pointer(const void *p, 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 */