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/*
This file is part of the FElt finite element analysis package.
Copyright (C) 1993-2000 Jason I. Gobat and Darren C. Atkinson
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 the Free Software
Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
*/
/************************************************************************
* File: Cache.c *
* *
* Description: This file contains the private functions definitions *
* for the caching mechanism of the Drawing widget. *
************************************************************************/
# include <stdio.h>
# include <X11/IntrinsicP.h>
# include "Cache.h"
# define CacheSize (1 << 4)
# define CacheMask (CacheSize - 1)
# define RemoveUnreferenced 0
/************************************************************************
Function: StringHash
Description: Returns a hash value for a string.
************************************************************************/
static unsigned StringHash (s)
char *s;
{
unsigned g;
unsigned h;
for (h = 0; *s; s ++)
if ((g = (h = (h << 4) + *s) & 0xf0000000))
h ^= (g >> 24) ^ g;
return h;
}
/************************************************************************
Function: DW_CacheCreate
Description: Creates, initialize, and returns a new cache.
************************************************************************/
Cache DW_CacheCreate ( )
{
Cache cache;
unsigned i;
cache = (Cache) XtMalloc (sizeof (struct cache_data) * CacheSize);
for (i = 0; i < CacheSize; i ++)
cache [i].next = NULL;
return cache;
}
/************************************************************************
Function: DW_CacheDestroy
Description: Destroys a cache.
************************************************************************/
void DW_CacheDestroy (cache)
Cache cache;
{
unsigned i;
CacheData ptr;
CacheData last;
for (i = 0; i < CacheSize; i ++) {
last = NULL;
for (ptr = cache [i].next; ptr; last = ptr, ptr = ptr -> next)
XtFree ((char *) last);
XtFree ((char *) last);
}
XtFree ((char *) cache);
}
/************************************************************************
Function: DW_CacheLookup
Description: Looks up a named value in a cache.
************************************************************************/
CacheData DW_CacheLookup (cache, name)
Cache cache;
String name;
{
unsigned idx;
CacheData ptr;
idx = StringHash (name) & CacheMask;
for (ptr = cache [idx].next; ptr; ptr = ptr -> next)
if (!strcmp (ptr -> name, name))
return ptr;
return NULL;
}
/************************************************************************
Function: DW_CacheInsert
Description: Inserts a named value in a cache.
************************************************************************/
CacheData DW_CacheInsert (cache, name, value)
Cache cache;
String name;
XtArgVal value;
{
unsigned idx;
CacheData ptr;
idx = StringHash (name) & CacheMask;
ptr = XtNew (struct cache_data);
ptr -> name = XtNewString (name);
ptr -> value = value;
ptr -> ref_count = 1;
if ((ptr -> next = cache [idx].next))
ptr -> next -> prev = ptr;
ptr -> prev = &cache [idx];
cache [idx].next = ptr;
return ptr;
}
/************************************************************************
Function: DW_CacheAddRef
Description: Increments the reference count of a named value.
************************************************************************/
void DW_CacheAddRef (data)
CacheData data;
{
data -> ref_count ++;
}
/************************************************************************
Function: DW_CacheDelRef
Description: Decrements the reference count of a named value.
************************************************************************/
void DW_CacheDelRef (data)
CacheData data;
{
data -> ref_count --;
# if RemoveUnreferenced
if (!data -> ref_count) {
if (data -> next)
data -> next -> prev = data -> prev;
data -> prev -> next = data -> next;
XtFree ((char *) data -> name);
XtFree ((char *) data);
}
# endif
}
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