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/*
* Copyright (c) 2008, 2009, 2010, 2012, 2013 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 mhash_finish(mhash_add(mhash_add(mhash_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 = mhash_add(hash, get_unaligned_u32(p));
n -= 4;
p += 1;
}
if (n) {
uint32_t tmp = 0;
memcpy(&tmp, p, n);
hash = mhash_add__(hash, tmp);
}
return mhash_finish(hash, orig_n);
}
/* Returns the hash of the 'n' 32-bit words at 'p', starting from 'basis'.
* 'p' must be properly aligned. */
uint32_t
hash_words(const uint32_t p[], size_t n_words, uint32_t basis)
{
uint32_t hash;
size_t i;
hash = basis;
for (i = 0; i < n_words; i++) {
hash = mhash_add(hash, p[i]);
}
return mhash_finish(hash, n_words * 4);
}
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);
}
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