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Diffstat (limited to 'lib/hash.h')
| -rw-r--r-- | lib/hash.h | 71 |
1 files changed, 71 insertions, 0 deletions
diff --git a/lib/hash.h b/lib/hash.h new file mode 100644 index 00000000..39894d9a --- /dev/null +++ b/lib/hash.h @@ -0,0 +1,71 @@ +/* + * Copyright (c) 2008, 2009 Nicira Networks. + * + * 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. + * + * 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. + */ +#ifndef HASH_H +#define HASH_H 1 + +#include <stddef.h> +#include <stdint.h> +#include <string.h> + +/* 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_bytes(const void *, size_t n_bytes, uint32_t basis); + +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; +} + +#endif /* hash.h */ |