quakeforge/libs/util/hash.c

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/*
hash.c
hash tables
Copyright (C) 2000 Bill Currie <bill@taniwha.org>
This program is free software; you can redistribute it and/or
modify it under the terms of the GNU General Public License
as published by the Free Software Foundation; either version 2
of the License, or (at your option) any later version.
This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
See the GNU General Public License for more details.
You should have received a copy of the GNU General Public License
along with this program; if not, write to:
Free Software Foundation, Inc.
59 Temple Place - Suite 330
Boston, MA 02111-1307, USA
*/
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static const char rcsid[] =
"$Id$";
#ifdef HAVE_CONFIG_H
# include "config.h"
#endif
#ifdef HAVE_STRING_H
# include <string.h>
#endif
#ifdef HAVE_STRINGS_H
# include <strings.h>
#endif
#include <math.h>
#include <stdlib.h> // should be sys/types.h, but bc is stupid
#include "QF/hash.h"
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#include "QF/sys.h"
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#include "compat.h"
struct hashlink_s {
struct hashlink_s *next;
struct hashlink_s **prev;
void *data;
};
struct hashtab_s {
size_t tab_size;
unsigned int size_bits;
size_t num_ele;
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void *user_data;
int (*compare)(void*,void*,void*);
unsigned long (*get_hash)(void*,void*);
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const char *(*get_key)(void*,void*);
void (*free_ele)(void*,void*);
struct hashlink_s *tab[1]; // variable size
};
unsigned long
Hash_String (const char *str)
{
#if 0
unsigned long h = 0;
while (*str) {
h = (h << 4) + (unsigned char)*str++;
if (h&0xf0000000)
h = (h ^ (h >> 24)) & 0xfffffff;
}
return h;
#else
// dx_hack_hash
// shamelessly stolen from Daniel Phillips <phillips@innominate.de>
// from his post to lkml
unsigned long hash0 = 0x12a3fe2d, hash1 = 0x37abe8f9;
while (*str) {
unsigned long hash = hash1 + (hash0 ^ ((unsigned char)*str++ * 71523));
if (hash < 0) hash -= 0x7fffffff;
hash1 = hash0;
hash0 = hash;
}
return hash0;
#endif
}
static unsigned long
get_hash (void *ele, void *data)
{
return (unsigned long)ele;
}
static int
compare (void *a, void *b, void *data)
{
return a == b;
}
static inline int
get_index (unsigned long hash, size_t size, size_t bits)
{
#if 0
unsigned long mask = ~0UL << bits;
unsigned long extract;
size -= 1;
for (extract = (hash & mask) >> bits;
extract;
extract = (hash & mask) >> bits) {
hash &= ~mask;
hash ^= extract;
} while (extract);
if (hash > size) {
extract = hash - size;
hash = size - (extract >> 1);
}
return hash;
#else
return hash % size;
#endif
}
hashtab_t *
Hash_NewTable (int tsize, const char *(*gk)(void*,void*),
void (*f)(void*,void*), void *ud)
{
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hashtab_t *tab = calloc (1, field_offset (hashtab_t, tab[tsize]));
if (!tab)
return 0;
tab->tab_size = tsize;
tab->user_data = ud;
tab->get_key = gk;
tab->free_ele = f;
while (tsize) {
tab->size_bits++;
tsize = ((unsigned int) tsize) >> 1;
}
tab->get_hash = get_hash;
tab->compare = compare;
return tab;
}
void
Hash_SetHashCompare (hashtab_t *tab, unsigned long (*gh)(void*,void*),
int (*cmp)(void*,void*,void*))
{
tab->get_hash = gh;
tab->compare = cmp;
}
void
Hash_DelTable (hashtab_t *tab)
{
Hash_FlushTable (tab);
free (tab);
}
void
Hash_FlushTable (hashtab_t *tab)
{
int i;
for (i = 0; i < tab->tab_size; i++) {
while (tab->tab[i]) {
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struct hashlink_s *t = tab->tab[i]->next;
void *data = tab->tab[i]->data;
free (tab->tab[i]);
tab->tab[i] = t;
if (tab->free_ele)
tab->free_ele (data, tab->user_data);
}
}
tab->num_ele = 0;
}
int
Hash_Add (hashtab_t *tab, void *ele)
{
unsigned long h = Hash_String (tab->get_key(ele, tab->user_data));
size_t ind = get_index (h, tab->tab_size, tab->size_bits);
struct hashlink_s *lnk = malloc (sizeof (struct hashlink_s));
if (!lnk)
return -1;
if (tab->tab[ind])
tab->tab[ind]->prev = &lnk->next;
lnk->next = tab->tab[ind];
lnk->prev = &tab->tab[ind];
lnk->data = ele;
tab->tab[ind] = lnk;
tab->num_ele++;
return 0;
}
int
Hash_AddElement (hashtab_t *tab, void *ele)
{
unsigned long h = tab->get_hash (ele, tab->user_data);
size_t ind = get_index (h, tab->tab_size, tab->size_bits);
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struct hashlink_s *lnk = malloc (sizeof (struct hashlink_s));
if (!lnk)
return -1;
if (tab->tab[ind])
tab->tab[ind]->prev = &lnk->next;
lnk->next = tab->tab[ind];
lnk->prev = &tab->tab[ind];
lnk->data = ele;
tab->tab[ind] = lnk;
tab->num_ele++;
return 0;
}
void *
Hash_Find (hashtab_t *tab, const char *key)
{
unsigned long h = Hash_String (key);
size_t ind = get_index (h, tab->tab_size, tab->size_bits);
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struct hashlink_s *lnk = tab->tab[ind];
while (lnk) {
if (strequal (key, tab->get_key (lnk->data, tab->user_data)))
return lnk->data;
lnk = lnk->next;
}
return 0;
}
void *
Hash_FindElement (hashtab_t *tab, void *ele)
{
unsigned long h = tab->get_hash (ele, tab->user_data);
size_t ind = get_index (h, tab->tab_size, tab->size_bits);
struct hashlink_s *lnk = tab->tab[ind];
while (lnk) {
if (tab->compare (lnk->data, ele, tab->user_data))
return lnk->data;
lnk = lnk->next;
}
return 0;
}
void *
Hash_Del (hashtab_t *tab, const char *key)
{
unsigned long h = Hash_String (key);
size_t ind = get_index (h, tab->tab_size, tab->size_bits);
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struct hashlink_s *lnk = tab->tab[ind];
void *data;
while (lnk) {
if (strequal (key, tab->get_key (lnk->data, tab->user_data))) {
data = lnk->data;
if (lnk->next)
lnk->next->prev = lnk->prev;
*lnk->prev = lnk->next;
free (lnk);
tab->num_ele--;
return data;
}
lnk = lnk->next;
}
return 0;
}
void *
Hash_DelElement (hashtab_t *tab, void *ele)
{
unsigned long h = tab->get_hash (ele, tab->user_data);
size_t ind = get_index (h, tab->tab_size, tab->size_bits);
struct hashlink_s *lnk = tab->tab[ind];
void *data;
while (lnk) {
if (tab->compare (lnk->data, ele, tab->user_data)) {
data = lnk->data;
if (lnk->next)
lnk->next->prev = lnk->prev;
*lnk->prev = lnk->next;
free (lnk);
tab->num_ele--;
return data;
}
lnk = lnk->next;
}
return 0;
}
void **
Hash_GetList (hashtab_t *tab)
{
void **list;
void **l;
size_t ind;
l = list = malloc ((tab->num_ele + 1) * sizeof (void*));
if (!list)
return 0;
for (ind = 0; ind < tab->tab_size; ind++) {
struct hashlink_s *lnk;
for (lnk = tab->tab[ind]; lnk; lnk = lnk->next) {
*l++ = lnk->data;
}
}
*l++ = 0;
return list;
}
static inline double
sqr (double x)
{
return x * x;
}
void
Hash_Stats (hashtab_t *tab)
{
int *lengths = calloc (tab->tab_size, sizeof (int));
int chains = 0;
int i;
int min_length = tab->num_ele;
int max_length = 0;
if (!lengths) {
Sys_Printf ("Hash_Stats: memory alloc error\n");
return;
}
for (i = 0; i < tab->tab_size; i++) {
struct hashlink_s *lnk = tab->tab[i];
while (lnk) {
lengths[i]++;
lnk = lnk->next;
}
if (lengths[i]) {
min_length = min (min_length, lengths[i]);
max_length = max (max_length, lengths[i]);
chains++;
}
}
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Sys_Printf ("%d elements\n", (int)tab->num_ele);
Sys_Printf ("%d / %d chains\n", chains, (int)tab->tab_size);
if (chains) {
double average = (double) tab->num_ele / chains;
double variance = 0;
Sys_Printf ("%d minium chain length\n", min_length);
Sys_Printf ("%d maximum chain length\n", max_length);
Sys_Printf ("%.3g average chain length\n", average);
for (i = 0; i < tab->tab_size; i++) {
if (lengths[i])
variance += sqr (lengths[i] - average);
}
variance /= chains;
Sys_Printf ("%.3g variance, %.3g standard deviation\n",
variance, sqrt (variance));
}
}