/*
- * Copyright (c) 2008, 2009 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.
#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
/* 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))))
+static inline uint32_t
+hash_rot(uint32_t x, int k)
+{
+ return (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)
+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;
+}
-#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 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);
+uint32_t hash_3words(uint32_t, uint32_t, uint32_t);
uint32_t hash_bytes(const void *, size_t n_bytes, uint32_t basis);
static inline uint32_t hash_string(const char *s, uint32_t basis)
}
/* This is Bob Jenkins' integer hash from
- * http://burtleburtle.net/bob/hash/integer.html, modified for style. */
+ * http://burtleburtle.net/bob/hash/integer.html, modified for style.
+ *
+ * This hash is faster than hash_2words(), but it isn't as good when 'basis' is
+ * important. So use this function for speed or hash_2words() for hash
+ * quality. */
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 += basis;
x -= x << 3;
x ^= x << 10;
x ^= x >> 15;
- return x + basis;
+ return x;
+}
+
+/* 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_double(double x, uint32_t basis)
+{
+ uint32_t value[2];
+ BUILD_ASSERT_DECL(sizeof x == sizeof value);
+
+ memcpy(value, &x, sizeof value);
+ return hash_3words(value[0], value[1], basis);
}
static inline uint32_t hash_pointer(const void *p, uint32_t basis)
return hash_int((uint32_t) (uintptr_t) p, basis);
}
+#ifdef __cplusplus
+}
+#endif
+
#endif /* hash.h */