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/*
* 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.
* 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 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, uint32_t basis)
{
uint32_t a, b, c;
a = b = c = 0xdeadbeef + (((uint32_t) n) << 2) + basis;
while (n > 3) {
a += p[0];
b += p[1];
c += p[2];
hash_mix(&a, &b, &c);
n -= 3;
p += 3;
}
switch (n) {
case 3:
c += p[2];
/* fall through */
case 2:
b += p[1];
/* fall through */
case 1:
a += p[0];
hash_final(&a, &b, &c);
/* fall through */
case 0:
break;
}
return c;
}
/* Returns the hash of 'a', 'b', and 'c'. */
uint32_t
hash_3words(uint32_t a, uint32_t b, uint32_t c)
{
a += 0xdeadbeef;
b += 0xdeadbeef;
c += 0xdeadbeef;
hash_final(&a, &b, &c);
return c;
}
/* Returns the hash of 'a' and 'b'. */
uint32_t
hash_2words(uint32_t a, uint32_t b)
{
return hash_3words(a, b, 0);
}
/* 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 uint8_t *p = p_;
uint32_t a, b, c;
a = b = c = 0xdeadbeef + n + basis;
while (n >= 12) {
a += get_unaligned_u32((uint32_t *) p);
b += get_unaligned_u32((uint32_t *) (p + 4));
c += get_unaligned_u32((uint32_t *) (p + 8));
hash_mix(&a, &b, &c);
n -= 12;
p += 12;
}
if (n) {
uint32_t tmp[3];
tmp[0] = tmp[1] = tmp[2] = 0;
memcpy(tmp, p, n);
a += tmp[0];
b += tmp[1];
c += tmp[2];
hash_final(&a, &b, &c);
}
return c;
}
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