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https://github.com/openvswitch/ovs
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Import from old repository commit 61ef2b42a9c4ba8e1600f15bb0236765edc2ad45.
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lib/hash.c
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85
lib/hash.c
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/*
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* Copyright (c) 2008, 2009 Nicira Networks.
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*
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* Permission to use, copy, modify, and/or distribute this software for any
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* purpose with or without fee is hereby granted, provided that the above
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* copyright notice and this permission notice appear in all copies.
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*
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* THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
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* WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
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* MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
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* ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
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* WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
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* ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
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* OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
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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 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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