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hash.c revision 1.4 
      1 /*	$NetBSD: hash.c,v 1.4 1998/02/22 15:40:41 christos Exp $	*/
      2 
      3 /*
      4  * Copyright (c) 1994, 1995 Jochen Pohl
      5  * All Rights Reserved.
      6  *
      7  * Redistribution and use in source and binary forms, with or without
      8  * modification, are permitted provided that the following conditions
      9  * are met:
     10  * 1. Redistributions of source code must retain the above copyright
     11  *    notice, this list of conditions and the following disclaimer.
     12  * 2. Redistributions in binary form must reproduce the above copyright
     13  *    notice, this list of conditions and the following disclaimer in the
     14  *    documentation and/or other materials provided with the distribution.
     15  * 3. All advertising materials mentioning features or use of this software
     16  *    must display the following acknowledgement:
     17  *      This product includes software developed by Jochen Pohl for
     18  *	The NetBSD Project.
     19  * 4. The name of the author may not be used to endorse or promote products
     20  *    derived from this software without specific prior written permission.
     21  *
     22  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
     23  * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
     24  * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
     25  * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
     26  * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
     27  * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
     28  * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
     29  * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
     30  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
     31  * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
     32  */
     33 
     34 #include <sys/cdefs.h>
     35 #ifndef lint
     36 __RCSID("$NetBSD: hash.c,v 1.4 1998/02/22 15:40:41 christos Exp $");
     37 #endif
     38 
     39 /*
     40  * XXX Really need a generalized hash table package
     41  */
     42 
     43 #include <stddef.h>
     44 #include <stdlib.h>
     45 #include <string.h>
     46 #include <limits.h>
     47 #include <err.h>
     48 
     49 #include "lint2.h"
     50 
     51 /* pointer to hash table, initialized in inithash() */
     52 static	hte_t	**htab;
     53 
     54 static	int	hash __P((const char *));
     55 
     56 /*
     57  * Initialize hash table.
     58  */
     59 void
     60 _inithash(tablep)
     61 	hte_t ***tablep;
     62 {
     63 
     64 	if (tablep == NULL)
     65 		tablep = &htab;
     66 
     67 	*tablep = xcalloc(HSHSIZ2, sizeof (hte_t *));
     68 }
     69 
     70 /*
     71  * Compute hash value from a string.
     72  */
     73 static int
     74 hash(s)
     75 	const	char *s;
     76 {
     77 	u_int	v;
     78 	const	u_char *us;
     79 
     80 	v = 0;
     81 	for (us = (const u_char *)s; *us != '\0'; us++) {
     82 		v = (v << sizeof (v)) + *us;
     83 		v ^= v >> (sizeof (v) * CHAR_BIT - sizeof (v));
     84 	}
     85 	return (v % HSHSIZ2);
     86 }
     87 
     88 /*
     89  * Look for a hash table entry. If no hash table entry for the
     90  * given name exists and mknew is set, create a new one.
     91  */
     92 hte_t *
     93 _hsearch(table, s, mknew)
     94 	hte_t	**table;
     95 	const	char *s;
     96 	int	mknew;
     97 {
     98 	int	h;
     99 	hte_t	*hte;
    100 
    101 	if (table == NULL)
    102 		table = htab;
    103 
    104 	h = hash(s);
    105 	for (hte = table[h]; hte != NULL; hte = hte->h_link) {
    106 		if (strcmp(hte->h_name, s) == 0)
    107 			break;
    108 	}
    109 
    110 	if (hte != NULL || !mknew)
    111 		return (hte);
    112 
    113 	/* create a new hte */
    114 	hte = xmalloc(sizeof (hte_t));
    115 	hte->h_name = xstrdup(s);
    116 	hte->h_lsym = &hte->h_syms;
    117 	hte->h_lcall = &hte->h_calls;
    118 	hte->h_lusym = &hte->h_usyms;
    119 	hte->h_link = table[h];
    120 	hte->h_hte = NULL;
    121 	table[h] = hte;
    122 
    123 	return (hte);
    124 }
    125 
    126 /*
    127  * Call function f for each name in the hash table.
    128  */
    129 void
    130 _forall(table, f)
    131 	hte_t	**table;
    132 	void	(*f) __P((hte_t *));
    133 {
    134 	int	i;
    135 	hte_t	*hte;
    136 
    137 	if (table == NULL)
    138 		table = htab;
    139 
    140 	for (i = 0; i < HSHSIZ2; i++) {
    141 		for (hte = table[i]; hte != NULL; hte = hte->h_link)
    142 			(*f)(hte);
    143 	}
    144 }
    145 
    146 /*
    147  * Free all contents of the hash table that this module allocated.
    148  */
    149 void
    150 _destroyhash(table)
    151 	hte_t	**table;
    152 {
    153 	int	i;
    154 	hte_t	*hte, *nexthte;
    155 
    156 	if (table == NULL)
    157 		err(1, "_destroyhash called on main hash table");
    158 
    159 	for (i = 0; i < HSHSIZ2; i++) {
    160 		for (hte = table[i]; hte != NULL; hte = nexthte) {
    161 			free((void *)hte->h_name);
    162 			nexthte = hte->h_link;
    163 			free(hte);
    164 		}
    165 	}
    166 	free(table);
    167 }
    168