| 1 | /* ocache.h -- a minimal object caching implementation. */
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| 2 |
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| 3 | /* Copyright (C) 2002 Free Software Foundation, Inc.
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| 4 |
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| 5 | This file is part of GNU Bash, the Bourne Again SHell.
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| 6 |
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| 7 | Bash is free software; you can redistribute it and/or modify it under
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| 8 | the terms of the GNU General Public License as published by the Free
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| 9 | Software Foundation; either version 2, or (at your option) any later
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| 10 | version.
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| 11 |
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| 12 | Bash is distributed in the hope that it will be useful, but WITHOUT ANY
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| 13 | WARRANTY; without even the implied warranty of MERCHANTABILITY or
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| 14 | FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
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| 15 | for more details.
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| 16 |
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| 17 | You should have received a copy of the GNU General Public License along
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| 18 | with Bash; see the file COPYING. If not, write to the Free Software
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| 19 | Foundation, 59 Temple Place, Suite 330, Boston, MA 02111 USA. */
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| 20 |
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| 21 | #if !defined (_OCACHE_H_)
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| 22 | #define _OCACHE_H_ 1
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| 23 |
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| 24 | #ifndef PTR_T
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| 25 |
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| 26 | #if defined (__STDC__)
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| 27 | # define PTR_T void *
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| 28 | #else
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| 29 | # define PTR_T char *
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| 30 | #endif
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| 31 |
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| 32 | #endif /* PTR_T */
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| 33 |
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| 34 | #define OC_MEMSET(memp, xch, nbytes) \
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| 35 | do { \
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| 36 | if ((nbytes) <= 32) { \
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| 37 | register char * mzp = (char *)(memp); \
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| 38 | unsigned long mctmp = (nbytes); \
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| 39 | register long mcn; \
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| 40 | if (mctmp < 8) mcn = 0; else { mcn = (mctmp-1)/8; mctmp &= 7; } \
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| 41 | switch (mctmp) { \
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| 42 | case 0: for(;;) { *mzp++ = xch; \
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| 43 | case 7: *mzp++ = xch; \
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| 44 | case 6: *mzp++ = xch; \
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| 45 | case 5: *mzp++ = xch; \
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| 46 | case 4: *mzp++ = xch; \
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| 47 | case 3: *mzp++ = xch; \
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| 48 | case 2: *mzp++ = xch; \
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| 49 | case 1: *mzp++ = xch; if(mcn <= 0) break; mcn--; } \
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| 50 | } \
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| 51 | } else \
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| 52 | memset ((memp), (xch), (nbytes)); \
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| 53 | } while(0)
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| 54 |
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| 55 | typedef struct objcache {
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| 56 | PTR_T data;
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| 57 | int cs; /* cache size, number of objects */
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| 58 | int nc; /* number of cache entries */
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| 59 | } sh_obj_cache_t;
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| 60 |
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| 61 | /* Create an object cache C of N pointers to OTYPE. */
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| 62 | #define ocache_create(c, otype, n) \
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| 63 | do { \
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| 64 | (c).data = xmalloc((n) * sizeof (otype *)); \
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| 65 | (c).cs = (n); \
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| 66 | (c).nc = 0; \
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| 67 | } while (0)
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| 68 |
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| 69 | /* Destroy an object cache C. */
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| 70 | #define ocache_destroy(c) \
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| 71 | do { \
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| 72 | if ((c).data) \
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| 73 | xfree ((c).data); \
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| 74 | (c).data = 0; \
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| 75 | (c).cs = (c).nc = 0; \
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| 76 | } while (0)
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| 77 |
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| 78 | /* Free all cached items, which are pointers to OTYPE, in object cache C. */
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| 79 | #define ocache_flush(c, otype) \
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| 80 | do { \
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| 81 | while ((c).nc > 0) \
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| 82 | xfree (((otype **)((c).data))[--(c).nc]); \
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| 83 | } while (0)
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| 84 |
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| 85 | /*
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| 86 | * Allocate a new item of type pointer to OTYPE, using data from object
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| 87 | * cache C if any cached items exist, otherwise calling xmalloc. Return
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| 88 | * the object in R.
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| 89 | */
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| 90 | #define ocache_alloc(c, otype, r) \
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| 91 | do { \
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| 92 | if ((c).nc > 0) { \
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| 93 | (r) = (otype *)((otype **)((c).data))[--(c).nc]; \
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| 94 | } else \
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| 95 | (r) = (otype *)xmalloc (sizeof (otype)); \
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| 96 | } while (0)
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| 97 |
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| 98 | /*
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| 99 | * Free an item R of type pointer to OTYPE, adding to object cache C if
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| 100 | * there is room and calling xfree if the cache is full. If R is added
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| 101 | * to the object cache, the contents are scrambled.
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| 102 | */
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| 103 | #define ocache_free(c, otype, r) \
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| 104 | do { \
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| 105 | if ((c).nc < (c).cs) { \
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| 106 | OC_MEMSET ((r), 0xdf, sizeof(otype)); \
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| 107 | ((otype **)((c).data))[(c).nc++] = (r); \
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| 108 | } else \
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| 109 | xfree (r); \
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| 110 | } while (0)
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| 111 |
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| 112 | /*
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| 113 | * One may declare and use an object cache as (for instance):
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| 114 | *
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| 115 | * sh_obj_cache_t wdcache = {0, 0, 0};
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| 116 | * sh_obj_cache_t wlcache = {0, 0, 0};
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| 117 | *
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| 118 | * ocache_create(wdcache, WORD_DESC, 30);
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| 119 | * ocache_create(wlcache, WORD_LIST, 30);
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| 120 | *
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| 121 | * WORD_DESC *wd;
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| 122 | * ocache_alloc (wdcache, WORD_DESC, wd);
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| 123 | *
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| 124 | * WORD_LIST *wl;
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| 125 | * ocache_alloc (wlcache, WORD_LIST, wl);
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| 126 | *
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| 127 | * ocache_free(wdcache, WORD_DESC, wd);
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| 128 | * ocache_free(wlcache, WORD_LIST, wl);
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| 129 | *
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| 130 | * The use is almost arbitrary.
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| 131 | */
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| 132 |
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| 133 | #endif /* _OCACHE_H */
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