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      1 /*	$NetBSD: hash.c,v 1.2 2017/01/28 21:31:45 christos Exp $	*/
      2 
      3 /*
      4  * Copyright (c) 1997 Kungliga Tekniska Hgskolan
      5  * (Royal Institute of Technology, Stockholm, Sweden).
      6  * All rights reserved.
      7  *
      8  * Redistribution and use in source and binary forms, with or without
      9  * modification, are permitted provided that the following conditions
     10  * are met:
     11  *
     12  * 1. Redistributions of source code must retain the above copyright
     13  *    notice, this list of conditions and the following disclaimer.
     14  *
     15  * 2. Redistributions in binary form must reproduce the above copyright
     16  *    notice, this list of conditions and the following disclaimer in the
     17  *    documentation and/or other materials provided with the distribution.
     18  *
     19  * 3. Neither the name of the Institute nor the names of its contributors
     20  *    may be used to endorse or promote products derived from this software
     21  *    without specific prior written permission.
     22  *
     23  * THIS SOFTWARE IS PROVIDED BY THE INSTITUTE AND CONTRIBUTORS ``AS IS'' AND
     24  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
     25  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
     26  * ARE DISCLAIMED.  IN NO EVENT SHALL THE INSTITUTE OR CONTRIBUTORS BE LIABLE
     27  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
     28  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
     29  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
     30  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
     31  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
     32  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
     33  * SUCH DAMAGE.
     34  */
     35 
     36 /*
     37  * Hash table functions
     38  */
     39 
     40 #include "gen_locl.h"
     41 
     42 __RCSID("$NetBSD: hash.c,v 1.2 2017/01/28 21:31:45 christos Exp $");
     43 
     44 static Hashentry *_search(Hashtab * htab,	/* The hash table */
     45 			  void *ptr);	/* And key */
     46 
     47 Hashtab *
     48 hashtabnew(int sz,
     49 	   int (*cmp) (void *, void *),
     50 	   unsigned (*hash) (void *))
     51 {
     52     Hashtab *htab;
     53     int i;
     54 
     55     assert(sz > 0);
     56 
     57     htab = (Hashtab *) malloc(sizeof(Hashtab) + (sz - 1) * sizeof(Hashentry *));
     58     if (htab == NULL)
     59 	return NULL;
     60 
     61     for (i = 0; i < sz; ++i)
     62 	htab->tab[i] = NULL;
     63 
     64     htab->cmp = cmp;
     65     htab->hash = hash;
     66     htab->sz = sz;
     67     return htab;
     68 }
     69 
     70 /* Intern search function */
     71 
     72 static Hashentry *
     73 _search(Hashtab * htab, void *ptr)
     74 {
     75     Hashentry *hptr;
     76 
     77     assert(htab && ptr);
     78 
     79     for (hptr = htab->tab[(*htab->hash) (ptr) % htab->sz];
     80 	 hptr;
     81 	 hptr = hptr->next)
     82 	if ((*htab->cmp) (ptr, hptr->ptr) == 0)
     83 	    break;
     84     return hptr;
     85 }
     86 
     87 /* Search for element in hash table */
     88 
     89 void *
     90 hashtabsearch(Hashtab * htab, void *ptr)
     91 {
     92     Hashentry *tmp;
     93 
     94     tmp = _search(htab, ptr);
     95     return tmp ? tmp->ptr : tmp;
     96 }
     97 
     98 /* add element to hash table */
     99 /* if already there, set new value */
    100 /* !NULL if succesful */
    101 
    102 void *
    103 hashtabadd(Hashtab * htab, void *ptr)
    104 {
    105     Hashentry *h = _search(htab, ptr);
    106     Hashentry **tabptr;
    107 
    108     assert(htab && ptr);
    109 
    110     if (h)
    111 	free((void *) h->ptr);
    112     else {
    113 	h = (Hashentry *) malloc(sizeof(Hashentry));
    114 	if (h == NULL) {
    115 	    return NULL;
    116 	}
    117 	tabptr = &htab->tab[(*htab->hash) (ptr) % htab->sz];
    118 	h->next = *tabptr;
    119 	*tabptr = h;
    120 	h->prev = tabptr;
    121 	if (h->next)
    122 	    h->next->prev = &h->next;
    123     }
    124     h->ptr = ptr;
    125     return h;
    126 }
    127 
    128 /* delete element with key key. Iff freep, free Hashentry->ptr */
    129 
    130 int
    131 _hashtabdel(Hashtab * htab, void *ptr, int freep)
    132 {
    133     Hashentry *h;
    134 
    135     assert(htab && ptr);
    136 
    137     h = _search(htab, ptr);
    138     if (h) {
    139 	if (freep)
    140 	    free(h->ptr);
    141 	if ((*(h->prev) = h->next))
    142 	    h->next->prev = h->prev;
    143 	free(h);
    144 	return 0;
    145     } else
    146 	return -1;
    147 }
    148 
    149 /* Do something for each element */
    150 
    151 void
    152 hashtabforeach(Hashtab * htab, int (*func) (void *ptr, void *arg),
    153 	       void *arg)
    154 {
    155     Hashentry **h, *g;
    156 
    157     assert(htab);
    158 
    159     for (h = htab->tab; h < &htab->tab[htab->sz]; ++h)
    160 	for (g = *h; g; g = g->next)
    161 	    if ((*func) (g->ptr, arg))
    162 		return;
    163 }
    164 
    165 /* standard hash-functions for strings */
    166 
    167 unsigned
    168 hashadd(const char *s)
    169 {				/* Standard hash function */
    170     unsigned i;
    171 
    172     assert(s);
    173 
    174     for (i = 0; *s; ++s)
    175 	i += *s;
    176     return i;
    177 }
    178 
    179 unsigned
    180 hashcaseadd(const char *s)
    181 {				/* Standard hash function */
    182     unsigned i;
    183 
    184     assert(s);
    185 
    186     for (i = 0; *s; ++s)
    187 	i += toupper((unsigned char)*s);
    188     return i;
    189 }
    190 
    191 #define TWELVE (sizeof(unsigned))
    192 #define SEVENTYFIVE (6*sizeof(unsigned))
    193 #define HIGH_BITS (~((unsigned)(~0) >> TWELVE))
    194 
    195 unsigned
    196 hashjpw(const char *ss)
    197 {				/* another hash function */
    198     unsigned h = 0;
    199     unsigned g;
    200     const unsigned char *s = (const unsigned char *)ss;
    201 
    202     for (; *s; ++s) {
    203 	h = (h << TWELVE) + *s;
    204 	if ((g = h & HIGH_BITS))
    205 	    h = (h ^ (g >> SEVENTYFIVE)) & ~HIGH_BITS;
    206     }
    207     return h;
    208 }
    209