mirror of
https://github.com/openvswitch/ovs
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1f26e79678
It's easier for the client to pass in data directly than it is for the client to stuff it into an array. These functions will have new users in upcoming commits.
104 lines
2.3 KiB
C
104 lines
2.3 KiB
C
/*
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* Copyright (c) 2008, 2009, 2010 Nicira Networks.
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*
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* Licensed under the Apache License, Version 2.0 (the "License");
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* you may not use this file except in compliance with the License.
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* You may obtain a copy of the License at:
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*/
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#include <config.h>
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#include "hash.h"
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#include <string.h>
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/* Returns the hash of the 'n' 32-bit words at 'p', starting from 'basis'.
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* 'p' must be properly aligned. */
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uint32_t
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hash_words(const uint32_t *p, size_t n, uint32_t basis)
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{
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uint32_t a, b, c;
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a = b = c = 0xdeadbeef + (((uint32_t) n) << 2) + basis;
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while (n > 3) {
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a += p[0];
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b += p[1];
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c += p[2];
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HASH_MIX(a, b, c);
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n -= 3;
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p += 3;
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}
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switch (n) {
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case 3:
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c += p[2];
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/* fall through */
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case 2:
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b += p[1];
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/* fall through */
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case 1:
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a += p[0];
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HASH_FINAL(a, b, c);
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/* fall through */
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case 0:
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break;
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}
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return c;
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}
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/* Returns the hash of 'a', 'b', and 'c'. */
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uint32_t
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hash_3words(uint32_t a, uint32_t b, uint32_t c)
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{
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a += 0xdeadbeef;
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b += 0xdeadbeef;
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c += 0xdeadbeef;
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HASH_FINAL(a, b, c);
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return c;
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}
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/* Returns the hash of 'a' and 'b'. */
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uint32_t
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hash_2words(uint32_t a, uint32_t b)
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{
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return hash_3words(a, b, 0);
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}
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/* Returns the hash of the 'n' bytes at 'p', starting from 'basis'. */
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uint32_t
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hash_bytes(const void *p_, size_t n, uint32_t basis)
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{
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const uint8_t *p = p_;
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uint32_t a, b, c;
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uint32_t tmp[3];
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a = b = c = 0xdeadbeef + n + basis;
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while (n >= sizeof tmp) {
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memcpy(tmp, p, sizeof tmp);
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a += tmp[0];
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b += tmp[1];
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c += tmp[2];
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HASH_MIX(a, b, c);
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n -= sizeof tmp;
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p += sizeof tmp;
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}
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if (n) {
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tmp[0] = tmp[1] = tmp[2] = 0;
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memcpy(tmp, p, n);
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a += tmp[0];
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b += tmp[1];
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c += tmp[2];
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HASH_FINAL(a, b, c);
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}
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return c;
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}
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