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/* ocache.h -- a minimal object caching implementation. */
/* Copyright (C) 2002 Free Software Foundation, Inc.
This file is part of GNU Bash, the Bourne Again SHell.
Bash 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.
Bash 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 Bash. If not, see <http://www.gnu.org/licenses/>.
*/
#if !defined (_OCACHE_H_)
#define _OCACHE_H_ 1
#ifndef PTR_T
#if defined (__STDC__)
# define PTR_T void *
#else
# define PTR_T char *
#endif
#endif /* PTR_T */
#define OC_MEMSET(memp, xch, nbytes) \
do { \
if ((nbytes) <= 32) { \
register char * mzp = (char *)(memp); \
unsigned long mctmp = (nbytes); \
register long mcn; \
if (mctmp < 8) mcn = 0; else { mcn = (mctmp-1)/8; mctmp &= 7; } \
switch (mctmp) { \
case 0: for(;;) { *mzp++ = xch; \
case 7: *mzp++ = xch; \
case 6: *mzp++ = xch; \
case 5: *mzp++ = xch; \
case 4: *mzp++ = xch; \
case 3: *mzp++ = xch; \
case 2: *mzp++ = xch; \
case 1: *mzp++ = xch; if(mcn <= 0) break; mcn--; } \
} \
} else \
memset ((memp), (xch), (nbytes)); \
} while(0)
typedef struct objcache {
PTR_T data;
int cs; /* cache size, number of objects */
int nc; /* number of cache entries */
} sh_obj_cache_t;
/* Create an object cache C of N pointers to OTYPE. */
#define ocache_create(c, otype, n) \
do { \
(c).data = xmalloc((n) * sizeof (otype *)); \
(c).cs = (n); \
(c).nc = 0; \
} while (0)
/* Destroy an object cache C. */
#define ocache_destroy(c) \
do { \
if ((c).data) \
xfree ((c).data); \
(c).data = 0; \
(c).cs = (c).nc = 0; \
} while (0)
/* Free all cached items, which are pointers to OTYPE, in object cache C. */
#define ocache_flush(c, otype) \
do { \
while ((c).nc > 0) \
xfree (((otype **)((c).data))[--(c).nc]); \
} while (0)
/*
* Allocate a new item of type pointer to OTYPE, using data from object
* cache C if any cached items exist, otherwise calling xmalloc. Return
* the object in R.
*/
#define ocache_alloc(c, otype, r) \
do { \
if ((c).nc > 0) { \
(r) = (otype *)((otype **)((c).data))[--(c).nc]; \
} else \
(r) = (otype *)xmalloc (sizeof (otype)); \
} while (0)
/*
* Free an item R of type pointer to OTYPE, adding to object cache C if
* there is room and calling xfree if the cache is full. If R is added
* to the object cache, the contents are scrambled.
*/
#define ocache_free(c, otype, r) \
do { \
if ((c).nc < (c).cs) { \
OC_MEMSET ((r), 0xdf, sizeof(otype)); \
((otype **)((c).data))[(c).nc++] = (r); \
} else \
xfree (r); \
} while (0)
/*
* One may declare and use an object cache as (for instance):
*
* sh_obj_cache_t wdcache = {0, 0, 0};
* sh_obj_cache_t wlcache = {0, 0, 0};
*
* ocache_create(wdcache, WORD_DESC, 30);
* ocache_create(wlcache, WORD_LIST, 30);
*
* WORD_DESC *wd;
* ocache_alloc (wdcache, WORD_DESC, wd);
*
* WORD_LIST *wl;
* ocache_alloc (wlcache, WORD_LIST, wl);
*
* ocache_free(wdcache, WORD_DESC, wd);
* ocache_free(wlcache, WORD_LIST, wl);
*
* The use is almost arbitrary.
*/
#endif /* _OCACHE_H */
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