41 lines
1.2 KiB
C
41 lines
1.2 KiB
C
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/* hash-pjw.c -- compute a hash value from a NUL-terminated string.
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Copyright (C) 2001, 2003, 2006, 2009-2020 Free Software Foundation, Inc.
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This program is free software: you can redistribute it and/or modify
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it under the terms of the GNU General Public License as published by
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the Free Software Foundation; either version 3 of the License, or
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(at your option) any later version.
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This program is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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GNU General Public License for more details.
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You should have received a copy of the GNU General Public License
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along with this program. If not, see <https://www.gnu.org/licenses/>. */
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#include <config.h>
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#include "hash-pjw.h"
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#include <limits.h>
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#define SIZE_BITS (sizeof (size_t) * CHAR_BIT)
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/* A hash function for NUL-terminated char* strings using
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the method described by Bruno Haible.
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See https://www.haible.de/bruno/hashfunc.html. */
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size_t
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hash_pjw (const void *x, size_t tablesize)
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{
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const char *s;
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size_t h = 0;
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for (s = x; *s; s++)
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h = *s + ((h << 9) | (h >> (SIZE_BITS - 9)));
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return h % tablesize;
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}
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