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/* Copyright 1990-92 GROUPE BULL -- See license conditions in file COPYRIGHT */
/*****************************************************************************\
* hashtable.c: *
* *
* XPM library *
* *
* Developed by Arnaud Le Hors *
* this originaly comes from Colas Nahaboo as a part of Wool *
* *
\*****************************************************************************/
#include "xpmP.h"
LFUNC(AtomMake, xpmHashAtom, (char *name, void *data));
LFUNC(HashTableGrows, int, (xpmHashTable *table));
static xpmHashAtom
AtomMake(name, data) /* makes an atom */
char *name; /* WARNING: is just pointed to */
void *data;
{
xpmHashAtom object = (xpmHashAtom) malloc(sizeof(struct _xpmHashAtom));
if (object) {
object->name = name;
object->data = data;
}
return object;
}
/************************\
* *
* hash table routines *
* *
\************************/
/*
* Hash function definition:
* HASH_FUNCTION: hash function, hash = hashcode, hp = pointer on char,
* hash2 = temporary for hashcode.
* INITIAL_TABLE_SIZE in slots
* HASH_TABLE_GROWS how hash table grows.
*/
/* Mock lisp function */
#define HASH_FUNCTION hash = (hash << 5) - hash + *hp++;
/* #define INITIAL_HASH_SIZE 2017 */
#define INITIAL_HASH_SIZE 256 /* should be enough for colors */
#define HASH_TABLE_GROWS size = size * 2;
/* aho-sethi-ullman's HPJ (sizes should be primes)*/
#ifdef notdef
#define HASH_FUNCTION hash <<= 4; hash += *hp++; \
if(hash2 = hash & 0xf0000000) hash ^= (hash2 >> 24) ^ hash2;
#define INITIAL_HASH_SIZE 4095 /* should be 2^n - 1 */
#define HASH_TABLE_GROWS size = size << 1 + 1;
#endif
/* GNU emacs function */
/*
#define HASH_FUNCTION hash = (hash << 3) + (hash >> 28) + *hp++;
#define INITIAL_HASH_SIZE 2017
#define HASH_TABLE_GROWS size = size * 2;
*/
/* end of hash functions */
/*
* The hash table is used to store atoms via their NAME:
*
* NAME --hash--> ATOM |--name--> "foo"
* |--data--> any value which has to be stored
*
*/
/*
* xpmHashSlot gives the slot (pointer to xpmHashAtom) of a name
* (slot points to NULL if it is not defined)
*
*/
xpmHashAtom *
xpmHashSlot(table, s)
xpmHashTable *table;
char *s;
{
xpmHashAtom *atomTable = table->atomTable;
unsigned int hash, hash2;
xpmHashAtom *p;
char *hp = s;
char *ns;
hash = 0;
while (*hp) { /* computes hash function */
HASH_FUNCTION
}
p = atomTable + hash % table->size;
while (*p) {
ns = (*p)->name;
if (ns[0] == s[0] && strcmp(ns, s) == 0)
break;
p--;
if (p < atomTable)
p = atomTable + table->size - 1;
}
return p;
}
static int
HashTableGrows(table)
xpmHashTable *table;
{
xpmHashAtom *atomTable = table->atomTable;
int size = table->size;
xpmHashAtom *t, *p;
int i;
int oldSize = size;
t = atomTable;
HASH_TABLE_GROWS
table->size = size;
table->limit = size / 3;
atomTable = (xpmHashAtom *) malloc(size * sizeof(*atomTable));
if (!atomTable)
return (XpmNoMemory);
table->atomTable = atomTable;
for (p = atomTable + size; p > atomTable;)
*--p = NULL;
for (i = 0, p = t; i < oldSize; i++, p++)
if (*p) {
xpmHashAtom *ps = xpmHashSlot(table, (*p)->name);
*ps = *p;
}
free(t);
return (XpmSuccess);
}
/*
* xpmHashIntern(table, name, data)
* an xpmHashAtom is created if name doesn't exist, with the given data.
*/
int
xpmHashIntern(table, tag, data)
xpmHashTable *table;
char *tag;
void *data;
{
xpmHashAtom *slot;
if (!*(slot = xpmHashSlot(table, tag))) {
/* undefined, make a new atom with the given data */
if (!(*slot = AtomMake(tag, data)))
return (XpmNoMemory);
if (table->used >= table->limit) {
int ErrorStatus;
xpmHashAtom new = *slot;
if ((ErrorStatus = HashTableGrows(table)) != XpmSuccess)
return(ErrorStatus);
table->used++;
return (XpmSuccess);
}
table->used++;
}
return (XpmSuccess);
}
/*
* must be called before allocating any atom
*/
int
xpmHashTableInit(table)
xpmHashTable *table;
{
xpmHashAtom *p;
xpmHashAtom *atomTable;
table->size = INITIAL_HASH_SIZE;
table->limit = table->size / 3;
table->used = 0;
atomTable = (xpmHashAtom *) malloc(table->size * sizeof(*atomTable));
if (!atomTable)
return (XpmNoMemory);
for (p = atomTable + table->size; p > atomTable;)
*--p = NULL;
table->atomTable = atomTable;
return (XpmSuccess);
}
/*
* frees a hashtable and all the stored atoms
*/
void
xpmHashTableFree(table)
xpmHashTable *table;
{
xpmHashAtom *p;
xpmHashAtom *atomTable = table->atomTable;
for (p = atomTable + table->size; p > atomTable;)
if (*--p)
free(*p);
free(atomTable);
table->atomTable = NULL;
}
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