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openvswitch/lib/hash.c
Jarno Rajahalme 4ad07ad7c1 hash: Make basis of hash_words64() 32 bits.
The basis of hash_words64() was 64 bits, even when the hash value is
32 bits, thus confusing the domain and the range of the function.
This patch fixes this by making the basis an uint32_t.

Suggested-by: Ben Pfaff <blp@nicira.com>
Signed-off-by: Jarno Rajahalme <jrajahalme@nicira.com>
2015-01-06 14:47:30 -08:00

338 lines
7.2 KiB
C

/*
* Copyright (c) 2008, 2009, 2010, 2012, 2013, 2014 Nicira, Inc.
*
* 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:
*
* 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.
*/
#include <config.h>
#include "hash.h"
#include <string.h>
#include "unaligned.h"
/* Returns the hash of 'a', 'b', and 'c'. */
uint32_t
hash_3words(uint32_t a, uint32_t b, uint32_t c)
{
return hash_finish(hash_add(hash_add(hash_add(a, 0), b), c), 12);
}
/* Returns the hash of the 'n' bytes at 'p', starting from 'basis'. */
uint32_t
hash_bytes(const void *p_, size_t n, uint32_t basis)
{
const uint32_t *p = p_;
size_t orig_n = n;
uint32_t hash;
hash = basis;
while (n >= 4) {
hash = hash_add(hash, get_unaligned_u32(p));
n -= 4;
p += 1;
}
if (n) {
uint32_t tmp = 0;
memcpy(&tmp, p, n);
hash = hash_add(hash, tmp);
}
return hash_finish(hash, orig_n);
}
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);
}
uint32_t
hash_words__(const uint32_t p[], size_t n_words, uint32_t basis)
{
return hash_words_inline(p, n_words, basis);
}
uint32_t
hash_words64__(const uint64_t p[], size_t n_words, uint32_t basis)
{
return hash_words64_inline(p, n_words, basis);
}
#if !(defined(__x86_64__))
void
hash_bytes128(const void *p_, size_t len, uint32_t basis, ovs_u128 *out)
{
const uint32_t c1 = 0x239b961b;
const uint32_t c2 = 0xab0e9789;
const uint32_t c3 = 0x38b34ae5;
const uint32_t c4 = 0xa1e38b93;
const uint8_t *tail, *data = (const uint8_t *)p_;
const uint32_t *blocks = (const uint32_t *)p_;
const int nblocks = len / 16;
uint32_t h1 = basis;
uint32_t h2 = basis;
uint32_t h3 = basis;
uint32_t h4 = basis;
uint32_t k1, k2, k3, k4;
/* Body */
for (int i = 0; i < nblocks; i++) {
uint32_t k1 = get_unaligned_u32(&blocks[i * 4 + 0]);
uint32_t k2 = get_unaligned_u32(&blocks[i * 4 + 1]);
uint32_t k3 = get_unaligned_u32(&blocks[i * 4 + 2]);
uint32_t k4 = get_unaligned_u32(&blocks[i * 4 + 3]);
k1 *= c1;
k1 = hash_rot(k1, 15);
k1 *= c2;
h1 ^= k1;
h1 = hash_rot(h1, 19);
h1 += h2;
h1 = h1 * 5 + 0x561ccd1b;
k2 *= c2;
k2 = hash_rot(k2, 16);
k2 *= c3;
h2 ^= k2;
h2 = hash_rot(h2, 17);
h2 += h3;
h2 = h2 * 5 + 0x0bcaa747;
k3 *= c3;
k3 = hash_rot(k3, 17);
k3 *= c4;
h3 ^= k3;
h3 = hash_rot(h3, 15);
h3 += h4;
h3 = h3 * 5 + 0x96cd1c35;
k4 *= c4;
k4 = hash_rot(k4, 18);
k4 *= c1;
h4 ^= k4;
h4 = hash_rot(h4, 13);
h4 += h1;
h4 = h4 * 5 + 0x32ac3b17;
}
/* Tail */
k1 = k2 = k3 = k4 = 0;
tail = data + nblocks * 16;
switch (len & 15) {
case 15:
k4 ^= tail[14] << 16;
case 14:
k4 ^= tail[13] << 8;
case 13:
k4 ^= tail[12] << 0;
k4 *= c4;
k4 = hash_rot(k4, 18);
k4 *= c1;
h4 ^= k4;
case 12:
k3 ^= tail[11] << 24;
case 11:
k3 ^= tail[10] << 16;
case 10:
k3 ^= tail[9] << 8;
case 9:
k3 ^= tail[8] << 0;
k3 *= c3;
k3 = hash_rot(k3, 17);
k3 *= c4;
h3 ^= k3;
case 8:
k2 ^= tail[7] << 24;
case 7:
k2 ^= tail[6] << 16;
case 6:
k2 ^= tail[5] << 8;
case 5:
k2 ^= tail[4] << 0;
k2 *= c2;
k2 = hash_rot(k2, 16);
k2 *= c3;
h2 ^= k2;
case 4:
k1 ^= tail[3] << 24;
case 3:
k1 ^= tail[2] << 16;
case 2:
k1 ^= tail[1] << 8;
case 1:
k1 ^= tail[0] << 0;
k1 *= c1;
k1 = hash_rot(k1, 15);
k1 *= c2;
h1 ^= k1;
};
/* Finalization */
h1 ^= len;
h2 ^= len;
h3 ^= len;
h4 ^= len;
h1 += h2;
h1 += h3;
h1 += h4;
h2 += h1;
h3 += h1;
h4 += h1;
h1 = mhash_finish(h1);
h2 = mhash_finish(h2);
h3 = mhash_finish(h3);
h4 = mhash_finish(h4);
h1 += h2;
h1 += h3;
h1 += h4;
h2 += h1;
h3 += h1;
h4 += h1;
out->u32[0] = h1;
out->u32[1] = h2;
out->u32[2] = h3;
out->u32[3] = h4;
}
#else /* __x86_64__ */
static inline uint64_t
hash_rot64(uint64_t x, int8_t r)
{
return (x << r) | (x >> (64 - r));
}
static inline uint64_t
fmix64(uint64_t k)
{
k ^= k >> 33;
k *= 0xff51afd7ed558ccdULL;
k ^= k >> 33;
k *= 0xc4ceb9fe1a85ec53ULL;
k ^= k >> 33;
return k;
}
void
hash_bytes128(const void *p_, size_t len, uint32_t basis, ovs_u128 *out)
{
const uint64_t c1 = 0x87c37b91114253d5ULL;
const uint64_t c2 = 0x4cf5ad432745937fULL;
const uint8_t *tail, *data = (const uint8_t *)p_;
const uint64_t *blocks = (const uint64_t *)p_;
const int nblocks = len / 16;
uint64_t h1 = basis;
uint64_t h2 = basis;
uint64_t k1, k2;
/* Body */
for (int i = 0; i < nblocks; i++) {
k1 = get_unaligned_u64(&blocks[i * 2 + 0]);
k2 = get_unaligned_u64(&blocks[i * 2 + 1]);
k1 *= c1;
k1 = hash_rot64(k1, 31);
k1 *= c2;
h1 ^= k1;
h1 = hash_rot64(h1, 27);
h1 += h2;
h1 = h1 * 5 + 0x52dce729;
k2 *= c2;
k2 = hash_rot64(k2, 33);
k2 *= c1;
h2 ^= k2;
h2 = hash_rot64(h2, 31);
h2 += h1;
h2 = h2 * 5 + 0x38495ab5;
}
/* Tail */
k1 = 0;
k2 = 0;
tail = data + nblocks * 16;
switch (len & 15) {
case 15:
k2 ^= ((uint64_t) tail[14]) << 48;
case 14:
k2 ^= ((uint64_t) tail[13]) << 40;
case 13:
k2 ^= ((uint64_t) tail[12]) << 32;
case 12:
k2 ^= ((uint64_t) tail[11]) << 24;
case 11:
k2 ^= ((uint64_t) tail[10]) << 16;
case 10:
k2 ^= ((uint64_t) tail[9]) << 8;
case 9:
k2 ^= ((uint64_t) tail[8]) << 0;
k2 *= c2;
k2 = hash_rot64(k2, 33);
k2 *= c1;
h2 ^= k2;
case 8:
k1 ^= ((uint64_t) tail[7]) << 56;
case 7:
k1 ^= ((uint64_t) tail[6]) << 48;
case 6:
k1 ^= ((uint64_t) tail[5]) << 40;
case 5:
k1 ^= ((uint64_t) tail[4]) << 32;
case 4:
k1 ^= ((uint64_t) tail[3]) << 24;
case 3:
k1 ^= ((uint64_t) tail[2]) << 16;
case 2:
k1 ^= ((uint64_t) tail[1]) << 8;
case 1:
k1 ^= ((uint64_t) tail[0]) << 0;
k1 *= c1;
k1 = hash_rot64(k1, 31);
k1 *= c2;
h1 ^= k1;
};
/* Finalization */
h1 ^= len;
h2 ^= len;
h1 += h2;
h2 += h1;
h1 = fmix64(h1);
h2 = fmix64(h2);
h1 += h2;
h2 += h1;
out->u64.lo = h1;
out->u64.hi = h2;
}
#endif /* __x86_64__ */