Mikio Hara
128 lines
4.1 KiB
C
128 lines
4.1 KiB
C
/* Copyright (c) 2008, 2009 The Board of Trustees of The Leland Stanford
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* Junior University
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*
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* We are making the OpenFlow specification and associated documentation
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* (Software) available for public use and benefit with the expectation
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* that others will use, modify and enhance the Software and contribute
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* those enhancements back to the community. However, since we would
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* like to make the Software available for broadest use, with as few
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* restrictions as possible permission is hereby granted, free of
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* charge, to any person obtaining a copy of this Software to deal in
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* the Software under the copyrights without restriction, including
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* without limitation the rights to use, copy, modify, merge, publish,
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* distribute, sublicense, and/or sell copies of the Software, and to
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* permit persons to whom the Software is furnished to do so, subject to
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* the following conditions:
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*
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* The above copyright notice and this permission notice shall be
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* included in all copies or substantial portions of the Software.
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*
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* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
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* EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
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* MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
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* NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS
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* BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN
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* ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
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* CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
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* SOFTWARE.
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*
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* The name and trademarks of copyright holder(s) may NOT be used in
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* advertising or publicity pertaining to the Software or any
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* derivatives without specific, written prior permission.
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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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/* This is the public domain lookup3 hash by Bob Jenkins from
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* http://burtleburtle.net/bob/c/lookup3.c, modified for style. */
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#define rot(x, k) (((x) << (k)) | ((x) >> (32 - (k))))
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#define mix(a, b, c) \
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do { \
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a -= c; a ^= rot(c, 4); c += b; \
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b -= a; b ^= rot(a, 6); a += c; \
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c -= b; c ^= rot(b, 8); b += a; \
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a -= c; a ^= rot(c, 16); c += b; \
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b -= a; b ^= rot(a, 19); a += c; \
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c -= b; c ^= rot(b, 4); b += a; \
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} while (0)
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#define final(a, b, c) \
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do { \
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c ^= b; c -= rot(b, 14); \
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a ^= c; a -= rot(c, 11); \
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b ^= a; b -= rot(a, 25); \
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c ^= b; c -= rot(b, 16); \
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a ^= c; a -= rot(c, 4); \
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b ^= a; b -= rot(a, 14); \
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c ^= b; c -= rot(b, 24); \
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} while (0)
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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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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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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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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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final(a, b, c);
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}
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return c;
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}
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