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/* Copyright 1996,1997,2001,2002,2009 Alain Knaff.
* This file is part of mtools.
*
* Mtools 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 3 of the License, or
* (at your option) any later version.
*
* Mtools 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 Mtools. If not, see <http://www.gnu.org/licenses/>.
*
* hash.c - hash table.
*/
#include "sysincludes.h"
#include "htable.h"
#include "mtools.h"
struct hashtable {
T_HashFunc f1,f2;
T_ComparFunc compar;
size_t size; /* actual size of the array */
size_t fill; /* number of deleted or in use slots */
size_t inuse; /* number of slots in use */
size_t max; /* maximal number of elements to keep efficient */
void **entries;
};
static size_t sizes[]=
{ 5, 11, 23, 47, 97, 197, 397, 797, 1597, 3203, 6421, 12853,
25717, 51437, 102877, 205759, 411527, 823117, 1646237,
3292489, 6584983, 13169977, 26339969, 52679969, 105359939,
210719881, 421439783, 842879579, 1685759167, 0 };
static int deleted=0;
static int unallocated=0;
static int alloc_ht(T_HashTable *H, size_t size)
{
int i;
size_t ii;
for(i=0; sizes[i]; i++)
if (sizes[i] > size*4 )
break;
if (!sizes[i])
for(i=0; sizes[i]; i++)
if (sizes[i] > size*2 )
break;
if (!sizes[i])
for(i=0; sizes[i]; i++)
if (sizes[i] > size)
break;
if(!sizes[i])
return -1;
size = sizes[i];
if(size < H->size)
size = H->size; /* never shrink the table */
H->max = size * 4 / 5 - 2;
H->size = size;
H->fill = 0;
H->inuse = 0;
H->entries = NewArray(size, void*);
if (H->entries == NULL)
return -1; /* out of memory error */
for(ii=0; ii < size; ii++)
H->entries[ii] = &unallocated;
return 0;
}
int make_ht(T_HashFunc f1, T_HashFunc f2, T_ComparFunc c, size_t size,
T_HashTable **H)
{
*H = New(T_HashTable);
if (*H == NULL){
return -1; /* out of memory error */
}
(*H)->f1 = f1;
(*H)->f2 = f2;
(*H)->compar = c;
(*H)->size = 0;
if(alloc_ht(*H,size))
return -1;
return 0;
}
int free_ht(T_HashTable *H, T_HashFunc entry_free)
{
size_t i;
if(entry_free)
for(i=0; i< H->size; i++)
if (H->entries[i] != &unallocated &&
H->entries[i] != &deleted)
entry_free(H->entries[i]);
Free(H->entries);
Free(H);
return 0;
}
/* add into hash table without checking for repeats */
static int _hash_add(T_HashTable *H,void *E, size_t *hint)
{
size_t f2, pos;
int ctr;
pos = H->f1(E) % H->size;
f2 = (size_t) -1;
ctr = 0;
while(H->entries[pos] != &unallocated &&
H->entries[pos] != &deleted){
if (f2 == (size_t) -1)
f2 = H->f2(E) % (H->size - 1);
pos = (pos+f2+1) % H->size;
ctr++;
}
if(H->entries[pos] == &unallocated)
H->fill++; /* only increase fill if the previous element was not yet
* counted, i.e. unallocated */
H->inuse++;
H->entries[pos] = E;
if(hint)
*hint = pos;
return 0;
}
static int rehash(T_HashTable *H)
{
size_t size,i;
void **oldentries;
/* resize the table */
size = H->size;
oldentries = H->entries;
if(alloc_ht(H,((H->inuse+1)*4+H->fill)/5))
return -1;
for(i=0; i < size; i++){
if(oldentries[i] != &unallocated && oldentries[i] != &deleted)
_hash_add(H, oldentries[i], 0);
}
Free(oldentries);
return 0;
}
int hash_add(T_HashTable *H, void *E, size_t *hint)
{
if (H->fill >= H->max)
rehash(H);
if (H->fill == H->size)
return -1; /*out of memory error */
return _hash_add(H,E, hint);
}
/* add into hash table without checking for repeats */
static int _hash_lookup(T_HashTable *H,void *E, void **E2,
size_t *hint, int isIdentity)
{
size_t f2, pos, upos, ttl;
pos = H->f1(E) % H->size;
ttl = H->size;
f2 = (size_t) -1;
upos = (size_t) -1;
while(ttl &&
H->entries[pos] != &unallocated &&
(H->entries[pos] == &deleted ||
((isIdentity || H->compar(H->entries[pos], E) != 0) &&
(!isIdentity || H->entries[pos] != E)))){
if (f2 == (size_t) -1)
f2 = H->f2(E) % (H->size - 1);
if (upos == (size_t) -1 && H->entries[pos] == &deleted)
upos = pos;
pos = (pos+f2+1) % H->size;
ttl--;
}
if(H->entries[pos] == &unallocated || !ttl)
return -1;
if (upos != (size_t) -1){
H->entries[upos] = H->entries[pos];
H->entries[pos] = &deleted;
pos = upos;
}
if(hint)
*hint = pos;
*E2= H->entries[pos];
return 0;
}
int hash_lookup(T_HashTable *H,void *E, void **E2,
size_t *hint)
{
return _hash_lookup(H, E, E2, hint, 0);
}
/* add into hash table without checking for repeats */
int hash_remove(T_HashTable *H,void *E, size_t hint)
{
void *E2;
if (hint < H->size && H->entries[hint] == E){
H->inuse--;
H->entries[hint] = &deleted;
return 0;
}
if(_hash_lookup(H, E, &E2, &hint, 1)) {
fprintf(stderr, "Removing non-existent entry\n");
exit(1);
}
H->inuse--;
H->entries[hint] = &deleted;
return 0;
}
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