NetBSD-5.0.2/usr.bin/config/hash.c
/* $NetBSD: hash.c,v 1.5 2006/12/27 17:50:27 alc Exp $ */
/*
* Copyright (c) 1992, 1993
* The Regents of the University of California. All rights reserved.
*
* This software was developed by the Computer Systems Engineering group
* at Lawrence Berkeley Laboratory under DARPA contract BG 91-66 and
* contributed to Berkeley.
*
* All advertising materials mentioning features or use of this software
* must display the following acknowledgement:
* This product includes software developed by the University of
* California, Lawrence Berkeley Laboratories.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
* 3. Neither the name of the University nor the names of its contributors
* may be used to endorse or promote products derived from this software
* without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
* ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
* SUCH DAMAGE.
*
* from: @(#)hash.c 8.1 (Berkeley) 6/6/93
*/
#if HAVE_NBTOOL_CONFIG_H
#include "nbtool_config.h"
#endif
#include <sys/param.h>
#include <assert.h>
#include <stdlib.h>
#include <string.h>
#include <util.h>
#include "defs.h"
/*
* Interned strings are kept in a hash table. By making each string
* unique, the program can compare strings by comparing pointers.
*/
struct hashent {
// XXXLUKEM: a SIMPLEQ might be more appropriate
TAILQ_ENTRY(hashent) h_next;
const char *h_name; /* the string */
u_int h_hash; /* its hash value */
void *h_value; /* other values (for name=value) */
};
struct hashtab {
size_t ht_size; /* size (power of 2) */
u_int ht_mask; /* == ht_size - 1 */
u_int ht_used; /* number of entries used */
u_int ht_lim; /* when to expand */
TAILQ_HEAD(hashenthead, hashent) *ht_tab;
};
static struct hashtab strings;
/*
* HASHFRACTION controls ht_lim, which in turn controls the average chain
* length. We allow a few entries, on average, as comparing them is usually
* cheap (the h_hash values prevent a strcmp).
*/
#define HASHFRACTION(sz) ((sz) * 3 / 2)
static void ht_expand(struct hashtab *);
static void ht_init(struct hashtab *, size_t);
static inline u_int hash(const char *);
static inline struct hashent *newhashent(const char *, u_int);
/*
* Initialize a new hash table. The size must be a power of 2.
*/
static void
ht_init(struct hashtab *ht, size_t sz)
{
u_int n;
ht->ht_tab = emalloc(sz * sizeof (ht->ht_tab[0]));
ht->ht_size = sz;
ht->ht_mask = sz - 1;
for (n = 0; n < sz; n++)
TAILQ_INIT(&ht->ht_tab[n]);
ht->ht_used = 0;
ht->ht_lim = HASHFRACTION(sz);
}
/*
* Expand an existing hash table.
*/
static void
ht_expand(struct hashtab *ht)
{
struct hashenthead *h, *oldh;
struct hashent *p;
u_int n, i;
n = ht->ht_size * 2;
h = emalloc(n * sizeof *h);
for (i = 0; i < n; i++)
TAILQ_INIT(&h[i]);
oldh = ht->ht_tab;
n--;
for (i = 0; i < ht->ht_size; i++) {
while ((p = TAILQ_FIRST(&oldh[i])) != NULL) {
TAILQ_REMOVE(&oldh[i], p, h_next);
// XXXLUKEM: really should be TAILQ_INSERT_TAIL
TAILQ_INSERT_HEAD(&h[p->h_hash & n], p, h_next);
}
}
free(ht->ht_tab);
ht->ht_tab = h;
ht->ht_mask = n;
ht->ht_size = ++n;
ht->ht_lim = HASHFRACTION(n);
}
/*
* Make a new hash entry, setting its h_next to NULL.
* If the free list is not empty, use the first entry from there,
* otherwise allocate a new entry.
*/
static inline struct hashent *
newhashent(const char *name, u_int h)
{
struct hashent *hp;
hp = ecalloc(1, sizeof(*hp));
hp->h_name = name;
hp->h_hash = h;
return (hp);
}
/*
* Hash a string.
*/
static inline u_int
hash(const char *str)
{
u_int h;
for (h = 0; *str;)
h = (h << 5) + h + *str++;
return (h);
}
void
initintern(void)
{
ht_init(&strings, 128);
}
/*
* Generate a single unique copy of the given string. We expect this
* function to be used frequently, so it should be fast.
*/
const char *
intern(const char *s)
{
struct hashtab *ht;
struct hashent *hp;
struct hashenthead *hpp;
u_int h;
char *p;
ht = &strings;
h = hash(s);
hpp = &ht->ht_tab[h & ht->ht_mask];
TAILQ_FOREACH(hp, hpp, h_next) {
if (hp->h_hash == h && strcmp(hp->h_name, s) == 0)
return (hp->h_name);
}
p = estrdup(s);
hp = newhashent(p, h);
TAILQ_INSERT_TAIL(hpp, hp, h_next);
if (++ht->ht_used > ht->ht_lim)
ht_expand(ht);
return (p);
}
struct hashtab *
ht_new(void)
{
struct hashtab *ht;
ht = ecalloc(1, sizeof *ht);
ht_init(ht, 8);
return (ht);
}
void
ht_free(struct hashtab *ht)
{
int i;
struct hashent *hp;
struct hashenthead *hpp;
for (i = 0; i < ht->ht_size; i++) {
hpp = &ht->ht_tab[i];
while ((hp = TAILQ_FIRST(hpp)) != NULL) {
TAILQ_REMOVE(hpp, hp, h_next);
free(hp);
ht->ht_used--;
}
}
assert(ht->ht_used == 0);
free(ht->ht_tab);
free(ht);
}
/*
* Insert and/or replace.
*/
int
ht_insrep(struct hashtab *ht, const char *nam, void *val, int replace)
{
struct hashent *hp;
struct hashenthead *hpp;
u_int h;
h = hash(nam);
hpp = &ht->ht_tab[h & ht->ht_mask];
TAILQ_FOREACH(hp, hpp, h_next) {
if (hp->h_name == nam) {
if (replace)
hp->h_value = val;
return (1);
}
}
hp = newhashent(nam, h);
TAILQ_INSERT_TAIL(hpp, hp, h_next);
hp->h_value = val;
if (++ht->ht_used > ht->ht_lim)
ht_expand(ht);
return (0);
}
/*
* Remove.
*/
int
ht_remove(struct hashtab *ht, const char *name)
{
struct hashent *hp;
struct hashenthead *hpp;
u_int h;
h = hash(name);
hpp = &ht->ht_tab[h & ht->ht_mask];
TAILQ_FOREACH(hp, hpp, h_next) {
if (hp->h_name != name)
continue;
TAILQ_REMOVE(hpp, hp, h_next);
free(hp);
ht->ht_used--;
return (0);
}
return (1);
}
void *
ht_lookup(struct hashtab *ht, const char *nam)
{
struct hashent *hp;
struct hashenthead *hpp;
u_int h;
h = hash(nam);
hpp = &ht->ht_tab[h & ht->ht_mask];
TAILQ_FOREACH(hp, hpp, h_next)
if (hp->h_name == nam)
return (hp->h_value);
return (NULL);
}
/*
* first parameter to callback is the entry name from the hash table
* second parameter is the value from the hash table
* third argument is passed through from the "arg" parameter to ht_enumerate()
*/
int
ht_enumerate(struct hashtab *ht, ht_callback cbfunc, void *arg)
{
struct hashent *hp;
struct hashenthead *hpp;
u_int i;
int rval = 0;
for (i = 0; i < ht->ht_size; i++) {
hpp = &ht->ht_tab[i];
TAILQ_FOREACH(hp, hpp, h_next)
rval += (*cbfunc)(hp->h_name, hp->h_value, arg);
}
return rval;
}