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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 2, 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; see the file COPYING. If not, write to the Free Software
+ Foundation, 59 Temple Place, Suite 330, Boston, MA 02111 USA. */
+
+#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 */