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991 lines
28 KiB
C
991 lines
28 KiB
C
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/* An expandable hash tables datatype.
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Copyright (C) 1999, 2000, 2001, 2002, 2003, 2004, 2009, 2010
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Free Software Foundation, Inc.
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Contributed by Vladimir Makarov (vmakarov@cygnus.com).
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This file is part of the libiberty library.
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Libiberty is free software; you can redistribute it and/or
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modify it under the terms of the GNU Library General Public
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License as published by the Free Software Foundation; either
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version 2 of the License, or (at your option) any later version.
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Libiberty 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 GNU
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Library General Public License for more details.
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You should have received a copy of the GNU Library General Public
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License along with libiberty; see the file COPYING.LIB. If
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not, write to the Free Software Foundation, Inc., 51 Franklin Street - Fifth Floor,
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Boston, MA 02110-1301, USA. */
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/* This package implements basic hash table functionality. It is possible
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to search for an entry, create an entry and destroy an entry.
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Elements in the table are generic pointers.
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The size of the table is not fixed; if the occupancy of the table
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grows too high the hash table will be expanded.
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The abstract data implementation is based on generalized Algorithm D
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from Knuth's book "The art of computer programming". Hash table is
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expanded by creation of new hash table and transferring elements from
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the old table to the new table. */
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#ifdef HAVE_CONFIG_H
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#include "config.h"
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#endif
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#include <sys/types.h>
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#ifdef HAVE_STDLIB_H
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#include <stdlib.h>
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#endif
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#ifdef HAVE_STRING_H
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#include <string.h>
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#endif
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#ifdef HAVE_MALLOC_H
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#include <malloc.h>
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#endif
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#ifdef HAVE_LIMITS_H
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#include <limits.h>
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#endif
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#ifdef HAVE_INTTYPES_H
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#include <inttypes.h>
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#endif
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#ifdef HAVE_STDINT_H
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#include <stdint.h>
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#endif
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#include <stdio.h>
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#include "libiberty.h"
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#include "ansidecl.h"
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#include "hashtab.h"
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#ifndef CHAR_BIT
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#define CHAR_BIT 8
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#endif
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static unsigned int higher_prime_index (unsigned long);
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static hashval_t htab_mod_1 (hashval_t, hashval_t, hashval_t, int);
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static hashval_t htab_mod (hashval_t, htab_t);
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static hashval_t htab_mod_m2 (hashval_t, htab_t);
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static hashval_t hash_pointer (const void *);
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static int eq_pointer (const void *, const void *);
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static int htab_expand (htab_t);
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static PTR *find_empty_slot_for_expand (htab_t, hashval_t);
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/* At some point, we could make these be NULL, and modify the
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hash-table routines to handle NULL specially; that would avoid
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function-call overhead for the common case of hashing pointers. */
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htab_hash htab_hash_pointer = hash_pointer;
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htab_eq htab_eq_pointer = eq_pointer;
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/* Table of primes and multiplicative inverses.
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Note that these are not minimally reduced inverses. Unlike when generating
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code to divide by a constant, we want to be able to use the same algorithm
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all the time. All of these inverses (are implied to) have bit 32 set.
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For the record, here's the function that computed the table; it's a
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vastly simplified version of the function of the same name from gcc. */
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#if 0
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unsigned int
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ceil_log2 (unsigned int x)
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{
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int i;
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for (i = 31; i >= 0 ; --i)
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if (x > (1u << i))
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return i+1;
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abort ();
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}
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unsigned int
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choose_multiplier (unsigned int d, unsigned int *mlp, unsigned char *shiftp)
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{
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unsigned long long mhigh;
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double nx;
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int lgup, post_shift;
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int pow, pow2;
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int n = 32, precision = 32;
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lgup = ceil_log2 (d);
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pow = n + lgup;
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pow2 = n + lgup - precision;
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nx = ldexp (1.0, pow) + ldexp (1.0, pow2);
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mhigh = nx / d;
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*shiftp = lgup - 1;
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*mlp = mhigh;
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return mhigh >> 32;
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}
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#endif
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struct prime_ent
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{
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hashval_t prime;
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hashval_t inv;
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hashval_t inv_m2; /* inverse of prime-2 */
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hashval_t shift;
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};
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static struct prime_ent const prime_tab[] = {
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{ 7, 0x24924925, 0x9999999b, 2 },
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{ 13, 0x3b13b13c, 0x745d1747, 3 },
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{ 31, 0x08421085, 0x1a7b9612, 4 },
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{ 61, 0x0c9714fc, 0x15b1e5f8, 5 },
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{ 127, 0x02040811, 0x0624dd30, 6 },
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{ 251, 0x05197f7e, 0x073260a5, 7 },
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{ 509, 0x01824366, 0x02864fc8, 8 },
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{ 1021, 0x00c0906d, 0x014191f7, 9 },
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{ 2039, 0x0121456f, 0x0161e69e, 10 },
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{ 4093, 0x00300902, 0x00501908, 11 },
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{ 8191, 0x00080041, 0x00180241, 12 },
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{ 16381, 0x000c0091, 0x00140191, 13 },
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{ 32749, 0x002605a5, 0x002a06e6, 14 },
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{ 65521, 0x000f00e2, 0x00110122, 15 },
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{ 131071, 0x00008001, 0x00018003, 16 },
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{ 262139, 0x00014002, 0x0001c004, 17 },
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{ 524287, 0x00002001, 0x00006001, 18 },
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{ 1048573, 0x00003001, 0x00005001, 19 },
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{ 2097143, 0x00004801, 0x00005801, 20 },
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{ 4194301, 0x00000c01, 0x00001401, 21 },
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{ 8388593, 0x00001e01, 0x00002201, 22 },
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{ 16777213, 0x00000301, 0x00000501, 23 },
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{ 33554393, 0x00001381, 0x00001481, 24 },
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{ 67108859, 0x00000141, 0x000001c1, 25 },
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{ 134217689, 0x000004e1, 0x00000521, 26 },
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{ 268435399, 0x00000391, 0x000003b1, 27 },
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{ 536870909, 0x00000019, 0x00000029, 28 },
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{ 1073741789, 0x0000008d, 0x00000095, 29 },
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{ 2147483647, 0x00000003, 0x00000007, 30 },
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/* Avoid "decimal constant so large it is unsigned" for 4294967291. */
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{ 0xfffffffb, 0x00000006, 0x00000008, 31 }
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};
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/* The following function returns an index into the above table of the
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nearest prime number which is greater than N, and near a power of two. */
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static unsigned int
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higher_prime_index (unsigned long n)
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{
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unsigned int low = 0;
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unsigned int high = sizeof(prime_tab) / sizeof(prime_tab[0]);
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while (low != high)
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{
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unsigned int mid = low + (high - low) / 2;
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if (n > prime_tab[mid].prime)
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low = mid + 1;
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else
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high = mid;
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}
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/* If we've run out of primes, abort. */
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if (n > prime_tab[low].prime)
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{
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fprintf (stderr, "Cannot find prime bigger than %lu\n", n);
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abort ();
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}
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return low;
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}
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/* Returns a hash code for P. */
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static hashval_t
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hash_pointer (const PTR p)
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{
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return (hashval_t) ((intptr_t)p >> 3);
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}
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/* Returns non-zero if P1 and P2 are equal. */
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static int
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eq_pointer (const PTR p1, const PTR p2)
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{
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return p1 == p2;
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}
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/* The parens around the function names in the next two definitions
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are essential in order to prevent macro expansions of the name.
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The bodies, however, are expanded as expected, so they are not
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recursive definitions. */
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/* Return the current size of given hash table. */
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#define htab_size(htab) ((htab)->size)
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size_t
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(htab_size) (htab_t htab)
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{
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return htab_size (htab);
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}
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/* Return the current number of elements in given hash table. */
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#define htab_elements(htab) ((htab)->n_elements - (htab)->n_deleted)
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size_t
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(htab_elements) (htab_t htab)
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{
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return htab_elements (htab);
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}
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/* Return X % Y. */
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static inline hashval_t
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htab_mod_1 (hashval_t x, hashval_t y, hashval_t inv, int shift)
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{
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/* The multiplicative inverses computed above are for 32-bit types, and
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requires that we be able to compute a highpart multiply. */
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#ifdef UNSIGNED_64BIT_TYPE
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__extension__ typedef UNSIGNED_64BIT_TYPE ull;
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if (sizeof (hashval_t) * CHAR_BIT <= 32)
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{
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hashval_t t1, t2, t3, t4, q, r;
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t1 = ((ull)x * inv) >> 32;
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t2 = x - t1;
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t3 = t2 >> 1;
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t4 = t1 + t3;
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q = t4 >> shift;
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r = x - (q * y);
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return r;
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}
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#endif
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/* Otherwise just use the native division routines. */
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return x % y;
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}
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/* Compute the primary hash for HASH given HTAB's current size. */
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static inline hashval_t
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htab_mod (hashval_t hash, htab_t htab)
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{
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const struct prime_ent *p = &prime_tab[htab->size_prime_index];
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return htab_mod_1 (hash, p->prime, p->inv, p->shift);
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}
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/* Compute the secondary hash for HASH given HTAB's current size. */
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static inline hashval_t
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htab_mod_m2 (hashval_t hash, htab_t htab)
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{
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const struct prime_ent *p = &prime_tab[htab->size_prime_index];
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return 1 + htab_mod_1 (hash, p->prime - 2, p->inv_m2, p->shift);
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}
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/* This function creates table with length slightly longer than given
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source length. Created hash table is initiated as empty (all the
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hash table entries are HTAB_EMPTY_ENTRY). The function returns the
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created hash table, or NULL if memory allocation fails. */
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htab_t
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htab_create_alloc (size_t size, htab_hash hash_f, htab_eq eq_f,
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htab_del del_f, htab_alloc alloc_f, htab_free free_f)
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{
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return htab_create_typed_alloc (size, hash_f, eq_f, del_f, alloc_f, alloc_f,
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free_f);
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}
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/* As above, but uses the variants of ALLOC_F and FREE_F which accept
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an extra argument. */
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htab_t
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htab_create_alloc_ex (size_t size, htab_hash hash_f, htab_eq eq_f,
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htab_del del_f, void *alloc_arg,
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htab_alloc_with_arg alloc_f,
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htab_free_with_arg free_f)
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{
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htab_t result;
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unsigned int size_prime_index;
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size_prime_index = higher_prime_index (size);
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size = prime_tab[size_prime_index].prime;
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result = (htab_t) (*alloc_f) (alloc_arg, 1, sizeof (struct htab));
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if (result == NULL)
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return NULL;
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result->entries = (PTR *) (*alloc_f) (alloc_arg, size, sizeof (PTR));
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if (result->entries == NULL)
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{
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if (free_f != NULL)
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(*free_f) (alloc_arg, result);
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return NULL;
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}
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result->size = size;
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result->size_prime_index = size_prime_index;
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result->hash_f = hash_f;
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result->eq_f = eq_f;
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result->del_f = del_f;
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result->alloc_arg = alloc_arg;
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result->alloc_with_arg_f = alloc_f;
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result->free_with_arg_f = free_f;
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return result;
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}
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/*
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@deftypefn Supplemental htab_t htab_create_typed_alloc (size_t @var{size}, @
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htab_hash @var{hash_f}, htab_eq @var{eq_f}, htab_del @var{del_f}, @
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htab_alloc @var{alloc_tab_f}, htab_alloc @var{alloc_f}, @
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htab_free @var{free_f})
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This function creates a hash table that uses two different allocators
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@var{alloc_tab_f} and @var{alloc_f} to use for allocating the table itself
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and its entries respectively. This is useful when variables of different
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types need to be allocated with different allocators.
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The created hash table is slightly larger than @var{size} and it is
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initially empty (all the hash table entries are @code{HTAB_EMPTY_ENTRY}).
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The function returns the created hash table, or @code{NULL} if memory
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allocation fails.
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@end deftypefn
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*/
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htab_t
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htab_create_typed_alloc (size_t size, htab_hash hash_f, htab_eq eq_f,
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htab_del del_f, htab_alloc alloc_tab_f,
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htab_alloc alloc_f, htab_free free_f)
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{
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htab_t result;
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unsigned int size_prime_index;
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size_prime_index = higher_prime_index (size);
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size = prime_tab[size_prime_index].prime;
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result = (htab_t) (*alloc_tab_f) (1, sizeof (struct htab));
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if (result == NULL)
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return NULL;
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result->entries = (PTR *) (*alloc_f) (size, sizeof (PTR));
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if (result->entries == NULL)
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{
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if (free_f != NULL)
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(*free_f) (result);
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return NULL;
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}
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result->size = size;
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result->size_prime_index = size_prime_index;
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result->hash_f = hash_f;
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result->eq_f = eq_f;
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result->del_f = del_f;
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result->alloc_f = alloc_f;
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result->free_f = free_f;
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return result;
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}
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/* Update the function pointers and allocation parameter in the htab_t. */
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void
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htab_set_functions_ex (htab_t htab, htab_hash hash_f, htab_eq eq_f,
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htab_del del_f, PTR alloc_arg,
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htab_alloc_with_arg alloc_f, htab_free_with_arg free_f)
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{
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htab->hash_f = hash_f;
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htab->eq_f = eq_f;
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htab->del_f = del_f;
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htab->alloc_arg = alloc_arg;
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htab->alloc_with_arg_f = alloc_f;
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htab->free_with_arg_f = free_f;
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}
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/* These functions exist solely for backward compatibility. */
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#undef htab_create
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htab_t
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htab_create (size_t size, htab_hash hash_f, htab_eq eq_f, htab_del del_f)
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{
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return htab_create_alloc (size, hash_f, eq_f, del_f, xcalloc, free);
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}
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htab_t
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htab_try_create (size_t size, htab_hash hash_f, htab_eq eq_f, htab_del del_f)
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{
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||
|
return htab_create_alloc (size, hash_f, eq_f, del_f, calloc, free);
|
||
|
}
|
||
|
|
||
|
/* This function frees all memory allocated for given hash table.
|
||
|
Naturally the hash table must already exist. */
|
||
|
|
||
|
void
|
||
|
htab_delete (htab_t htab)
|
||
|
{
|
||
|
size_t size = htab_size (htab);
|
||
|
PTR *entries = htab->entries;
|
||
|
int i;
|
||
|
|
||
|
if (htab->del_f)
|
||
|
for (i = size - 1; i >= 0; i--)
|
||
|
if (entries[i] != HTAB_EMPTY_ENTRY && entries[i] != HTAB_DELETED_ENTRY)
|
||
|
(*htab->del_f) (entries[i]);
|
||
|
|
||
|
if (htab->free_f != NULL)
|
||
|
{
|
||
|
(*htab->free_f) (entries);
|
||
|
(*htab->free_f) (htab);
|
||
|
}
|
||
|
else if (htab->free_with_arg_f != NULL)
|
||
|
{
|
||
|
(*htab->free_with_arg_f) (htab->alloc_arg, entries);
|
||
|
(*htab->free_with_arg_f) (htab->alloc_arg, htab);
|
||
|
}
|
||
|
}
|
||
|
|
||
|
/* This function clears all entries in the given hash table. */
|
||
|
|
||
|
void
|
||
|
htab_empty (htab_t htab)
|
||
|
{
|
||
|
size_t size = htab_size (htab);
|
||
|
PTR *entries = htab->entries;
|
||
|
int i;
|
||
|
|
||
|
if (htab->del_f)
|
||
|
for (i = size - 1; i >= 0; i--)
|
||
|
if (entries[i] != HTAB_EMPTY_ENTRY && entries[i] != HTAB_DELETED_ENTRY)
|
||
|
(*htab->del_f) (entries[i]);
|
||
|
|
||
|
/* Instead of clearing megabyte, downsize the table. */
|
||
|
if (size > 1024*1024 / sizeof (PTR))
|
||
|
{
|
||
|
int nindex = higher_prime_index (1024 / sizeof (PTR));
|
||
|
int nsize = prime_tab[nindex].prime;
|
||
|
|
||
|
if (htab->free_f != NULL)
|
||
|
(*htab->free_f) (htab->entries);
|
||
|
else if (htab->free_with_arg_f != NULL)
|
||
|
(*htab->free_with_arg_f) (htab->alloc_arg, htab->entries);
|
||
|
if (htab->alloc_with_arg_f != NULL)
|
||
|
htab->entries = (PTR *) (*htab->alloc_with_arg_f) (htab->alloc_arg, nsize,
|
||
|
sizeof (PTR *));
|
||
|
else
|
||
|
htab->entries = (PTR *) (*htab->alloc_f) (nsize, sizeof (PTR *));
|
||
|
htab->size = nsize;
|
||
|
htab->size_prime_index = nindex;
|
||
|
}
|
||
|
else
|
||
|
memset (entries, 0, size * sizeof (PTR));
|
||
|
htab->n_deleted = 0;
|
||
|
htab->n_elements = 0;
|
||
|
}
|
||
|
|
||
|
/* Similar to htab_find_slot, but without several unwanted side effects:
|
||
|
- Does not call htab->eq_f when it finds an existing entry.
|
||
|
- Does not change the count of elements/searches/collisions in the
|
||
|
hash table.
|
||
|
This function also assumes there are no deleted entries in the table.
|
||
|
HASH is the hash value for the element to be inserted. */
|
||
|
|
||
|
static PTR *
|
||
|
find_empty_slot_for_expand (htab_t htab, hashval_t hash)
|
||
|
{
|
||
|
hashval_t index = htab_mod (hash, htab);
|
||
|
size_t size = htab_size (htab);
|
||
|
PTR *slot = htab->entries + index;
|
||
|
hashval_t hash2;
|
||
|
|
||
|
if (*slot == HTAB_EMPTY_ENTRY)
|
||
|
return slot;
|
||
|
else if (*slot == HTAB_DELETED_ENTRY)
|
||
|
abort ();
|
||
|
|
||
|
hash2 = htab_mod_m2 (hash, htab);
|
||
|
for (;;)
|
||
|
{
|
||
|
index += hash2;
|
||
|
if (index >= size)
|
||
|
index -= size;
|
||
|
|
||
|
slot = htab->entries + index;
|
||
|
if (*slot == HTAB_EMPTY_ENTRY)
|
||
|
return slot;
|
||
|
else if (*slot == HTAB_DELETED_ENTRY)
|
||
|
abort ();
|
||
|
}
|
||
|
}
|
||
|
|
||
|
/* The following function changes size of memory allocated for the
|
||
|
entries and repeatedly inserts the table elements. The occupancy
|
||
|
of the table after the call will be about 50%. Naturally the hash
|
||
|
table must already exist. Remember also that the place of the
|
||
|
table entries is changed. If memory allocation failures are allowed,
|
||
|
this function will return zero, indicating that the table could not be
|
||
|
expanded. If all goes well, it will return a non-zero value. */
|
||
|
|
||
|
static int
|
||
|
htab_expand (htab_t htab)
|
||
|
{
|
||
|
PTR *oentries;
|
||
|
PTR *olimit;
|
||
|
PTR *p;
|
||
|
PTR *nentries;
|
||
|
size_t nsize, osize, elts;
|
||
|
unsigned int oindex, nindex;
|
||
|
|
||
|
oentries = htab->entries;
|
||
|
oindex = htab->size_prime_index;
|
||
|
osize = htab->size;
|
||
|
olimit = oentries + osize;
|
||
|
elts = htab_elements (htab);
|
||
|
|
||
|
/* Resize only when table after removal of unused elements is either
|
||
|
too full or too empty. */
|
||
|
if (elts * 2 > osize || (elts * 8 < osize && osize > 32))
|
||
|
{
|
||
|
nindex = higher_prime_index (elts * 2);
|
||
|
nsize = prime_tab[nindex].prime;
|
||
|
}
|
||
|
else
|
||
|
{
|
||
|
nindex = oindex;
|
||
|
nsize = osize;
|
||
|
}
|
||
|
|
||
|
if (htab->alloc_with_arg_f != NULL)
|
||
|
nentries = (PTR *) (*htab->alloc_with_arg_f) (htab->alloc_arg, nsize,
|
||
|
sizeof (PTR *));
|
||
|
else
|
||
|
nentries = (PTR *) (*htab->alloc_f) (nsize, sizeof (PTR *));
|
||
|
if (nentries == NULL)
|
||
|
return 0;
|
||
|
htab->entries = nentries;
|
||
|
htab->size = nsize;
|
||
|
htab->size_prime_index = nindex;
|
||
|
htab->n_elements -= htab->n_deleted;
|
||
|
htab->n_deleted = 0;
|
||
|
|
||
|
p = oentries;
|
||
|
do
|
||
|
{
|
||
|
PTR x = *p;
|
||
|
|
||
|
if (x != HTAB_EMPTY_ENTRY && x != HTAB_DELETED_ENTRY)
|
||
|
{
|
||
|
PTR *q = find_empty_slot_for_expand (htab, (*htab->hash_f) (x));
|
||
|
|
||
|
*q = x;
|
||
|
}
|
||
|
|
||
|
p++;
|
||
|
}
|
||
|
while (p < olimit);
|
||
|
|
||
|
if (htab->free_f != NULL)
|
||
|
(*htab->free_f) (oentries);
|
||
|
else if (htab->free_with_arg_f != NULL)
|
||
|
(*htab->free_with_arg_f) (htab->alloc_arg, oentries);
|
||
|
return 1;
|
||
|
}
|
||
|
|
||
|
/* This function searches for a hash table entry equal to the given
|
||
|
element. It cannot be used to insert or delete an element. */
|
||
|
|
||
|
PTR
|
||
|
htab_find_with_hash (htab_t htab, const PTR element, hashval_t hash)
|
||
|
{
|
||
|
hashval_t index, hash2;
|
||
|
size_t size;
|
||
|
PTR entry;
|
||
|
|
||
|
htab->searches++;
|
||
|
size = htab_size (htab);
|
||
|
index = htab_mod (hash, htab);
|
||
|
|
||
|
entry = htab->entries[index];
|
||
|
if (entry == HTAB_EMPTY_ENTRY
|
||
|
|| (entry != HTAB_DELETED_ENTRY && (*htab->eq_f) (entry, element)))
|
||
|
return entry;
|
||
|
|
||
|
hash2 = htab_mod_m2 (hash, htab);
|
||
|
for (;;)
|
||
|
{
|
||
|
htab->collisions++;
|
||
|
index += hash2;
|
||
|
if (index >= size)
|
||
|
index -= size;
|
||
|
|
||
|
entry = htab->entries[index];
|
||
|
if (entry == HTAB_EMPTY_ENTRY
|
||
|
|| (entry != HTAB_DELETED_ENTRY && (*htab->eq_f) (entry, element)))
|
||
|
return entry;
|
||
|
}
|
||
|
}
|
||
|
|
||
|
/* Like htab_find_slot_with_hash, but compute the hash value from the
|
||
|
element. */
|
||
|
|
||
|
PTR
|
||
|
htab_find (htab_t htab, const PTR element)
|
||
|
{
|
||
|
return htab_find_with_hash (htab, element, (*htab->hash_f) (element));
|
||
|
}
|
||
|
|
||
|
/* This function searches for a hash table slot containing an entry
|
||
|
equal to the given element. To delete an entry, call this with
|
||
|
insert=NO_INSERT, then call htab_clear_slot on the slot returned
|
||
|
(possibly after doing some checks). To insert an entry, call this
|
||
|
with insert=INSERT, then write the value you want into the returned
|
||
|
slot. When inserting an entry, NULL may be returned if memory
|
||
|
allocation fails. */
|
||
|
|
||
|
PTR *
|
||
|
htab_find_slot_with_hash (htab_t htab, const PTR element,
|
||
|
hashval_t hash, enum insert_option insert)
|
||
|
{
|
||
|
PTR *first_deleted_slot;
|
||
|
hashval_t index, hash2;
|
||
|
size_t size;
|
||
|
PTR entry;
|
||
|
|
||
|
size = htab_size (htab);
|
||
|
if (insert == INSERT && size * 3 <= htab->n_elements * 4)
|
||
|
{
|
||
|
if (htab_expand (htab) == 0)
|
||
|
return NULL;
|
||
|
size = htab_size (htab);
|
||
|
}
|
||
|
|
||
|
index = htab_mod (hash, htab);
|
||
|
|
||
|
htab->searches++;
|
||
|
first_deleted_slot = NULL;
|
||
|
|
||
|
entry = htab->entries[index];
|
||
|
if (entry == HTAB_EMPTY_ENTRY)
|
||
|
goto empty_entry;
|
||
|
else if (entry == HTAB_DELETED_ENTRY)
|
||
|
first_deleted_slot = &htab->entries[index];
|
||
|
else if ((*htab->eq_f) (entry, element))
|
||
|
return &htab->entries[index];
|
||
|
|
||
|
hash2 = htab_mod_m2 (hash, htab);
|
||
|
for (;;)
|
||
|
{
|
||
|
htab->collisions++;
|
||
|
index += hash2;
|
||
|
if (index >= size)
|
||
|
index -= size;
|
||
|
|
||
|
entry = htab->entries[index];
|
||
|
if (entry == HTAB_EMPTY_ENTRY)
|
||
|
goto empty_entry;
|
||
|
else if (entry == HTAB_DELETED_ENTRY)
|
||
|
{
|
||
|
if (!first_deleted_slot)
|
||
|
first_deleted_slot = &htab->entries[index];
|
||
|
}
|
||
|
else if ((*htab->eq_f) (entry, element))
|
||
|
return &htab->entries[index];
|
||
|
}
|
||
|
|
||
|
empty_entry:
|
||
|
if (insert == NO_INSERT)
|
||
|
return NULL;
|
||
|
|
||
|
if (first_deleted_slot)
|
||
|
{
|
||
|
htab->n_deleted--;
|
||
|
*first_deleted_slot = HTAB_EMPTY_ENTRY;
|
||
|
return first_deleted_slot;
|
||
|
}
|
||
|
|
||
|
htab->n_elements++;
|
||
|
return &htab->entries[index];
|
||
|
}
|
||
|
|
||
|
/* Like htab_find_slot_with_hash, but compute the hash value from the
|
||
|
element. */
|
||
|
|
||
|
PTR *
|
||
|
htab_find_slot (htab_t htab, const PTR element, enum insert_option insert)
|
||
|
{
|
||
|
return htab_find_slot_with_hash (htab, element, (*htab->hash_f) (element),
|
||
|
insert);
|
||
|
}
|
||
|
|
||
|
/* This function deletes an element with the given value from hash
|
||
|
table (the hash is computed from the element). If there is no matching
|
||
|
element in the hash table, this function does nothing. */
|
||
|
|
||
|
void
|
||
|
htab_remove_elt (htab_t htab, PTR element)
|
||
|
{
|
||
|
htab_remove_elt_with_hash (htab, element, (*htab->hash_f) (element));
|
||
|
}
|
||
|
|
||
|
|
||
|
/* This function deletes an element with the given value from hash
|
||
|
table. If there is no matching element in the hash table, this
|
||
|
function does nothing. */
|
||
|
|
||
|
void
|
||
|
htab_remove_elt_with_hash (htab_t htab, PTR element, hashval_t hash)
|
||
|
{
|
||
|
PTR *slot;
|
||
|
|
||
|
slot = htab_find_slot_with_hash (htab, element, hash, NO_INSERT);
|
||
|
if (*slot == HTAB_EMPTY_ENTRY)
|
||
|
return;
|
||
|
|
||
|
if (htab->del_f)
|
||
|
(*htab->del_f) (*slot);
|
||
|
|
||
|
*slot = HTAB_DELETED_ENTRY;
|
||
|
htab->n_deleted++;
|
||
|
}
|
||
|
|
||
|
/* This function clears a specified slot in a hash table. It is
|
||
|
useful when you've already done the lookup and don't want to do it
|
||
|
again. */
|
||
|
|
||
|
void
|
||
|
htab_clear_slot (htab_t htab, PTR *slot)
|
||
|
{
|
||
|
if (slot < htab->entries || slot >= htab->entries + htab_size (htab)
|
||
|
|| *slot == HTAB_EMPTY_ENTRY || *slot == HTAB_DELETED_ENTRY)
|
||
|
abort ();
|
||
|
|
||
|
if (htab->del_f)
|
||
|
(*htab->del_f) (*slot);
|
||
|
|
||
|
*slot = HTAB_DELETED_ENTRY;
|
||
|
htab->n_deleted++;
|
||
|
}
|
||
|
|
||
|
/* This function scans over the entire hash table calling
|
||
|
CALLBACK for each live entry. If CALLBACK returns false,
|
||
|
the iteration stops. INFO is passed as CALLBACK's second
|
||
|
argument. */
|
||
|
|
||
|
void
|
||
|
htab_traverse_noresize (htab_t htab, htab_trav callback, PTR info)
|
||
|
{
|
||
|
PTR *slot;
|
||
|
PTR *limit;
|
||
|
|
||
|
slot = htab->entries;
|
||
|
limit = slot + htab_size (htab);
|
||
|
|
||
|
do
|
||
|
{
|
||
|
PTR x = *slot;
|
||
|
|
||
|
if (x != HTAB_EMPTY_ENTRY && x != HTAB_DELETED_ENTRY)
|
||
|
if (!(*callback) (slot, info))
|
||
|
break;
|
||
|
}
|
||
|
while (++slot < limit);
|
||
|
}
|
||
|
|
||
|
/* Like htab_traverse_noresize, but does resize the table when it is
|
||
|
too empty to improve effectivity of subsequent calls. */
|
||
|
|
||
|
void
|
||
|
htab_traverse (htab_t htab, htab_trav callback, PTR info)
|
||
|
{
|
||
|
size_t size = htab_size (htab);
|
||
|
if (htab_elements (htab) * 8 < size && size > 32)
|
||
|
htab_expand (htab);
|
||
|
|
||
|
htab_traverse_noresize (htab, callback, info);
|
||
|
}
|
||
|
|
||
|
/* Return the fraction of fixed collisions during all work with given
|
||
|
hash table. */
|
||
|
|
||
|
double
|
||
|
htab_collisions (htab_t htab)
|
||
|
{
|
||
|
if (htab->searches == 0)
|
||
|
return 0.0;
|
||
|
|
||
|
return (double) htab->collisions / (double) htab->searches;
|
||
|
}
|
||
|
|
||
|
/* Hash P as a null-terminated string.
|
||
|
|
||
|
Copied from gcc/hashtable.c. Zack had the following to say with respect
|
||
|
to applicability, though note that unlike hashtable.c, this hash table
|
||
|
implementation re-hashes rather than chain buckets.
|
||
|
|
||
|
http://gcc.gnu.org/ml/gcc-patches/2001-08/msg01021.html
|
||
|
From: Zack Weinberg <zackw@panix.com>
|
||
|
Date: Fri, 17 Aug 2001 02:15:56 -0400
|
||
|
|
||
|
I got it by extracting all the identifiers from all the source code
|
||
|
I had lying around in mid-1999, and testing many recurrences of
|
||
|
the form "H_n = H_{n-1} * K + c_n * L + M" where K, L, M were either
|
||
|
prime numbers or the appropriate identity. This was the best one.
|
||
|
I don't remember exactly what constituted "best", except I was
|
||
|
looking at bucket-length distributions mostly.
|
||
|
|
||
|
So it should be very good at hashing identifiers, but might not be
|
||
|
as good at arbitrary strings.
|
||
|
|
||
|
I'll add that it thoroughly trounces the hash functions recommended
|
||
|
for this use at http://burtleburtle.net/bob/hash/index.html, both
|
||
|
on speed and bucket distribution. I haven't tried it against the
|
||
|
function they just started using for Perl's hashes. */
|
||
|
|
||
|
hashval_t
|
||
|
htab_hash_string (const PTR p)
|
||
|
{
|
||
|
const unsigned char *str = (const unsigned char *) p;
|
||
|
hashval_t r = 0;
|
||
|
unsigned char c;
|
||
|
|
||
|
while ((c = *str++) != 0)
|
||
|
r = r * 67 + c - 113;
|
||
|
|
||
|
return r;
|
||
|
}
|
||
|
|
||
|
/* DERIVED FROM:
|
||
|
--------------------------------------------------------------------
|
||
|
lookup2.c, by Bob Jenkins, December 1996, Public Domain.
|
||
|
hash(), hash2(), hash3, and mix() are externally useful functions.
|
||
|
Routines to test the hash are included if SELF_TEST is defined.
|
||
|
You can use this free for any purpose. It has no warranty.
|
||
|
--------------------------------------------------------------------
|
||
|
*/
|
||
|
|
||
|
/*
|
||
|
--------------------------------------------------------------------
|
||
|
mix -- mix 3 32-bit values reversibly.
|
||
|
For every delta with one or two bit set, and the deltas of all three
|
||
|
high bits or all three low bits, whether the original value of a,b,c
|
||
|
is almost all zero or is uniformly distributed,
|
||
|
* If mix() is run forward or backward, at least 32 bits in a,b,c
|
||
|
have at least 1/4 probability of changing.
|
||
|
* If mix() is run forward, every bit of c will change between 1/3 and
|
||
|
2/3 of the time. (Well, 22/100 and 78/100 for some 2-bit deltas.)
|
||
|
mix() was built out of 36 single-cycle latency instructions in a
|
||
|
structure that could supported 2x parallelism, like so:
|
||
|
a -= b;
|
||
|
a -= c; x = (c>>13);
|
||
|
b -= c; a ^= x;
|
||
|
b -= a; x = (a<<8);
|
||
|
c -= a; b ^= x;
|
||
|
c -= b; x = (b>>13);
|
||
|
...
|
||
|
Unfortunately, superscalar Pentiums and Sparcs can't take advantage
|
||
|
of that parallelism. They've also turned some of those single-cycle
|
||
|
latency instructions into multi-cycle latency instructions. Still,
|
||
|
this is the fastest good hash I could find. There were about 2^^68
|
||
|
to choose from. I only looked at a billion or so.
|
||
|
--------------------------------------------------------------------
|
||
|
*/
|
||
|
/* same, but slower, works on systems that might have 8 byte hashval_t's */
|
||
|
#define mix(a,b,c) \
|
||
|
{ \
|
||
|
a -= b; a -= c; a ^= (c>>13); \
|
||
|
b -= c; b -= a; b ^= (a<< 8); \
|
||
|
c -= a; c -= b; c ^= ((b&0xffffffff)>>13); \
|
||
|
a -= b; a -= c; a ^= ((c&0xffffffff)>>12); \
|
||
|
b -= c; b -= a; b = (b ^ (a<<16)) & 0xffffffff; \
|
||
|
c -= a; c -= b; c = (c ^ (b>> 5)) & 0xffffffff; \
|
||
|
a -= b; a -= c; a = (a ^ (c>> 3)) & 0xffffffff; \
|
||
|
b -= c; b -= a; b = (b ^ (a<<10)) & 0xffffffff; \
|
||
|
c -= a; c -= b; c = (c ^ (b>>15)) & 0xffffffff; \
|
||
|
}
|
||
|
|
||
|
/*
|
||
|
--------------------------------------------------------------------
|
||
|
hash() -- hash a variable-length key into a 32-bit value
|
||
|
k : the key (the unaligned variable-length array of bytes)
|
||
|
len : the length of the key, counting by bytes
|
||
|
level : can be any 4-byte value
|
||
|
Returns a 32-bit value. Every bit of the key affects every bit of
|
||
|
the return value. Every 1-bit and 2-bit delta achieves avalanche.
|
||
|
About 36+6len instructions.
|
||
|
|
||
|
The best hash table sizes are powers of 2. There is no need to do
|
||
|
mod a prime (mod is sooo slow!). If you need less than 32 bits,
|
||
|
use a bitmask. For example, if you need only 10 bits, do
|
||
|
h = (h & hashmask(10));
|
||
|
In which case, the hash table should have hashsize(10) elements.
|
||
|
|
||
|
If you are hashing n strings (ub1 **)k, do it like this:
|
||
|
for (i=0, h=0; i<n; ++i) h = hash( k[i], len[i], h);
|
||
|
|
||
|
By Bob Jenkins, 1996. bob_jenkins@burtleburtle.net. You may use this
|
||
|
code any way you wish, private, educational, or commercial. It's free.
|
||
|
|
||
|
See http://burtleburtle.net/bob/hash/evahash.html
|
||
|
Use for hash table lookup, or anything where one collision in 2^32 is
|
||
|
acceptable. Do NOT use for cryptographic purposes.
|
||
|
--------------------------------------------------------------------
|
||
|
*/
|
||
|
|
||
|
hashval_t
|
||
|
iterative_hash (const PTR k_in /* the key */,
|
||
|
register size_t length /* the length of the key */,
|
||
|
register hashval_t initval /* the previous hash, or
|
||
|
an arbitrary value */)
|
||
|
{
|
||
|
register const unsigned char *k = (const unsigned char *)k_in;
|
||
|
register hashval_t a,b,c,len;
|
||
|
|
||
|
/* Set up the internal state */
|
||
|
len = length;
|
||
|
a = b = 0x9e3779b9; /* the golden ratio; an arbitrary value */
|
||
|
c = initval; /* the previous hash value */
|
||
|
|
||
|
/*---------------------------------------- handle most of the key */
|
||
|
#ifndef WORDS_BIGENDIAN
|
||
|
/* On a little-endian machine, if the data is 4-byte aligned we can hash
|
||
|
by word for better speed. This gives nondeterministic results on
|
||
|
big-endian machines. */
|
||
|
if (sizeof (hashval_t) == 4 && (((size_t)k)&3) == 0)
|
||
|
while (len >= 12) /* aligned */
|
||
|
{
|
||
|
a += *(hashval_t *)(k+0);
|
||
|
b += *(hashval_t *)(k+4);
|
||
|
c += *(hashval_t *)(k+8);
|
||
|
mix(a,b,c);
|
||
|
k += 12; len -= 12;
|
||
|
}
|
||
|
else /* unaligned */
|
||
|
#endif
|
||
|
while (len >= 12)
|
||
|
{
|
||
|
a += (k[0] +((hashval_t)k[1]<<8) +((hashval_t)k[2]<<16) +((hashval_t)k[3]<<24));
|
||
|
b += (k[4] +((hashval_t)k[5]<<8) +((hashval_t)k[6]<<16) +((hashval_t)k[7]<<24));
|
||
|
c += (k[8] +((hashval_t)k[9]<<8) +((hashval_t)k[10]<<16)+((hashval_t)k[11]<<24));
|
||
|
mix(a,b,c);
|
||
|
k += 12; len -= 12;
|
||
|
}
|
||
|
|
||
|
/*------------------------------------- handle the last 11 bytes */
|
||
|
c += length;
|
||
|
switch(len) /* all the case statements fall through */
|
||
|
{
|
||
|
case 11: c+=((hashval_t)k[10]<<24);
|
||
|
case 10: c+=((hashval_t)k[9]<<16);
|
||
|
case 9 : c+=((hashval_t)k[8]<<8);
|
||
|
/* the first byte of c is reserved for the length */
|
||
|
case 8 : b+=((hashval_t)k[7]<<24);
|
||
|
case 7 : b+=((hashval_t)k[6]<<16);
|
||
|
case 6 : b+=((hashval_t)k[5]<<8);
|
||
|
case 5 : b+=k[4];
|
||
|
case 4 : a+=((hashval_t)k[3]<<24);
|
||
|
case 3 : a+=((hashval_t)k[2]<<16);
|
||
|
case 2 : a+=((hashval_t)k[1]<<8);
|
||
|
case 1 : a+=k[0];
|
||
|
/* case 0: nothing left to add */
|
||
|
}
|
||
|
mix(a,b,c);
|
||
|
/*-------------------------------------------- report the result */
|
||
|
return c;
|
||
|
}
|