/* $TOG: patcache.c /main/8 1997/06/12 11:51:59 barstow $ *//*Copyright (c) 1991  X ConsortiumPermission is hereby granted, free of charge, to any person obtaining a copyof this software and associated documentation files (the "Software"), to dealin the Software without restriction, including without limitation the rightsto use, copy, modify, merge, publish, distribute, sublicense, and/or sellcopies of the Software, and to permit persons to whom the Software isfurnished to do so, subject to the following conditions:The above copyright notice and this permission notice shall be included inall copies or substantial portions of the Software.THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS ORIMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.  IN NO EVENT SHALL THEX CONSORTIUM BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER INAN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR INCONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.Except as contained in this notice, the name of the X Consortium shall not beused in advertising or otherwise to promote the sale, use or other dealingsin this Software without prior written authorization from the X Consortium.*//* $XFree86: xc/lib/font/util/patcache.c,v 3.0.4.1 1997/07/05 15:55:37 dawes Exp $ *//* * Author:  Keith Packard, MIT X Consortium */#include    <fontmisc.h>#include    <fontstruct.h>/* * Static sized hash table for looking up font name patterns * * LRU entries, reusing old entries */#define NBUCKETS	16#define NENTRIES	64#define UNSET		(NENTRIES+1)typedef unsigned char	EntryPtr;typedef struct _FontPatternCacheEntry {    struct _FontPatternCacheEntry   *next, **prev;    short			    patlen;    char			    *pattern;    int				    hash;    FontPtr			    pFont;	/* associated font */} FontPatternCacheEntryRec, *FontPatternCacheEntryPtr;typedef struct _FontPatternCache {    FontPatternCacheEntryPtr	buckets[NBUCKETS];    FontPatternCacheEntryRec	entries[NENTRIES];    FontPatternCacheEntryPtr	free;} FontPatternCacheRec;/* Create and initialize cache */FontPatternCachePtrMakeFontPatternCache (){    FontPatternCachePtr	cache;    int			i;    cache = (FontPatternCachePtr) xalloc (sizeof *cache);    if (!cache)	return 0;    for (i = 0; i < NENTRIES; i++) {	cache->entries[i].patlen = 0;	cache->entries[i].pattern = 0;	cache->entries[i].pFont = 0;    }    EmptyFontPatternCache (cache);    return cache;}/* toss cache */voidFreeFontPatternCache (cache)    FontPatternCachePtr	cache;{    int	    i;    for (i = 0; i < NENTRIES; i++)	xfree (cache->entries[i].pattern);    xfree (cache);}/* compute id for string */staticHash (string, len)    char    *string;    int	    len;{    int	hash;    hash = 0;    while (len--)	hash = (hash << 1) ^ *string++;    if (hash < 0)	hash = -hash;    return hash;}/* Empty cache (for rehash) */voidEmptyFontPatternCache (cache)    FontPatternCachePtr	cache;{    int	    i;        for (i = 0; i < NBUCKETS; i++)	cache->buckets[i] = 0;    for (i = 0; i < NENTRIES; i++)    {	cache->entries[i].next = &cache->entries[i+1];	cache->entries[i].prev = 0;	cache->entries[i].pFont = 0;	xfree (cache->entries[i].pattern);	cache->entries[i].pattern = 0;	cache->entries[i].patlen = 0;    }    cache->free = &cache->entries[0];    cache->entries[NENTRIES - 1].next = 0;}/* add entry */voidCacheFontPattern (cache, pattern, patlen, pFont)    FontPatternCachePtr	cache;    char		*pattern;    int			patlen;    FontPtr		pFont;{    FontPatternCacheEntryPtr	e;    char			*newpat;    int				i;    newpat = (char *) xalloc (patlen);    if (!newpat)	return;    if (cache->free)    {	e = cache->free;	cache->free = e->next;    }    else    {    	i = rand ();    	if (i < 0)	    i = -i;    	i %= NENTRIES;	e = &cache->entries[i];	if (e->next)	    e->next->prev = e->prev;	*e->prev = e->next;	xfree (e->pattern);    }    /* set pattern */    memcpy (newpat, pattern, patlen);    e->pattern = newpat;    e->patlen = patlen;    /* link to new hash chain */    e->hash = Hash (pattern, patlen);    i = e->hash % NBUCKETS;    e->next = cache->buckets[i];    if (e->next)	e->next->prev = &(e->next);    cache->buckets[i] = e;    e->prev = &(cache->buckets[i]);    e->pFont = pFont;}/* find matching entry */FontPtrFindCachedFontPattern (cache, pattern, patlen)    FontPatternCachePtr	cache;    char		*pattern;    int			patlen;{    int				hash;    int				i;    FontPatternCacheEntryPtr	e;    hash = Hash (pattern, patlen);    i = hash % NBUCKETS;    for (e = cache->buckets[i]; e; e = e->next)    {	if (e->patlen == patlen && e->hash == hash &&	    !memcmp (e->pattern, pattern, patlen))	{	    return e->pFont;	}    }    return 0;}voidRemoveCachedFontPattern (cache, pFont)    FontPatternCachePtr	cache;    FontPtr		pFont;{    FontPatternCacheEntryPtr	e;    int				i;    for (i = 0; i < NENTRIES; i++)    {	if ((e = &cache->entries[i])->pFont == pFont)	{	    e->pFont = 0;	    if (e->next)		e->next->prev = e->prev;	    *e->prev = e->next;	    e->next = cache->free;	    cache->free = e;	    xfree (e->pattern);	    e->pattern = 0;	}    }}