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/*
* Copyright (c) 2008, 2009 Nicira Networks.
*
* 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>
/* 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 the pair of aligned 32-bit words at 'p', starting from
* 'basis'. */
uint32_t
hash_2words(const uint32_t *p, uint32_t basis)
{
uint32_t a, b, c;
a = b = c = 0xdeadbeef + (2 << 2) + basis;
b += p[1];
a += p[0];
HASH_FINAL(a, b, c);
return c;
}
/* 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;
uint32_t tmp[3];
a = b = c = 0xdeadbeef + n + basis;
while (n >= sizeof tmp) {
memcpy(tmp, p, sizeof tmp);
a += tmp[0];
b += tmp[1];
c += tmp[2];
HASH_MIX(a, b, c);
n -= sizeof tmp;
p += sizeof tmp;
}
if (n) {
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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