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annotate lib/hash-pjw.c @ 17342:c75939cb6254

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merge with default branch
author Michael Goffioul <michael.goffioul@gmail.com>
date Thu, 21 Feb 2013 14:57:31 +0000
parents e542fd46ad6f
children
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1 /* hash-pjw.c -- compute a hash value from a NUL-terminated string.
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2
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3 Copyright (C) 2001, 2003, 2006, 2009-2013 Free Software Foundation, Inc.
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4
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5 This program is free software: you can redistribute it and/or modify
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6 it under the terms of the GNU General Public License as published by
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7 the Free Software Foundation; either version 3 of the License, or
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8 (at your option) any later version.
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9
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10 This program is distributed in the hope that it will be useful,
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11 but WITHOUT ANY WARRANTY; without even the implied warranty of
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12 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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13 GNU General Public License for more details.
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15 You should have received a copy of the GNU General Public License
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16 along with this program. If not, see <http://www.gnu.org/licenses/>. */
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17
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18 #include <config.h>
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20 #include "hash-pjw.h"
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22 #include <limits.h>
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23
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24 #define SIZE_BITS (sizeof (size_t) * CHAR_BIT)
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26 /* A hash function for NUL-terminated char* strings using
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27 the method described by Bruno Haible.
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28 See http://www.haible.de/bruno/hashfunc.html. */
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30 size_t
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31 hash_pjw (const void *x, size_t tablesize)
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32 {
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33 const char *s;
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34 size_t h = 0;
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35
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36 for (s = x; *s; s++)
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37 h = *s + ((h << 9) | (h >> (SIZE_BITS - 9)));
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39 return h % tablesize;
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40 }