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7117c2d2 JA |
1 | /* ocache.h -- a minimal object caching implementation. */ |
2 | ||
3 | /* Copyright (C) 2002 Free Software Foundation, Inc. | |
4 | ||
5 | This file is part of GNU Bash, the Bourne Again SHell. | |
6 | ||
3185942a JA |
7 | Bash is free software: you can redistribute it and/or modify |
8 | it under the terms of the GNU General Public License as published by | |
9 | the Free Software Foundation, either version 3 of the License, or | |
10 | (at your option) any later version. | |
11 | ||
12 | Bash is distributed in the hope that it will be useful, | |
13 | but WITHOUT ANY WARRANTY; without even the implied warranty of | |
14 | MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the | |
15 | GNU General Public License for more details. | |
16 | ||
17 | You should have received a copy of the GNU General Public License | |
18 | along with Bash. If not, see <http://www.gnu.org/licenses/>. | |
19 | */ | |
7117c2d2 JA |
20 | |
21 | #if !defined (_OCACHE_H_) | |
22 | #define _OCACHE_H_ 1 | |
23 | ||
24 | #ifndef PTR_T | |
25 | ||
26 | #if defined (__STDC__) | |
27 | # define PTR_T void * | |
28 | #else | |
29 | # define PTR_T char * | |
30 | #endif | |
31 | ||
32 | #endif /* PTR_T */ | |
33 | ||
34 | #define OC_MEMSET(memp, xch, nbytes) \ | |
35 | do { \ | |
36 | if ((nbytes) <= 32) { \ | |
37 | register char * mzp = (char *)(memp); \ | |
38 | unsigned long mctmp = (nbytes); \ | |
39 | register long mcn; \ | |
40 | if (mctmp < 8) mcn = 0; else { mcn = (mctmp-1)/8; mctmp &= 7; } \ | |
41 | switch (mctmp) { \ | |
42 | case 0: for(;;) { *mzp++ = xch; \ | |
43 | case 7: *mzp++ = xch; \ | |
44 | case 6: *mzp++ = xch; \ | |
45 | case 5: *mzp++ = xch; \ | |
46 | case 4: *mzp++ = xch; \ | |
47 | case 3: *mzp++ = xch; \ | |
48 | case 2: *mzp++ = xch; \ | |
49 | case 1: *mzp++ = xch; if(mcn <= 0) break; mcn--; } \ | |
50 | } \ | |
51 | } else \ | |
52 | memset ((memp), (xch), (nbytes)); \ | |
53 | } while(0) | |
54 | ||
55 | typedef struct objcache { | |
56 | PTR_T data; | |
57 | int cs; /* cache size, number of objects */ | |
58 | int nc; /* number of cache entries */ | |
59 | } sh_obj_cache_t; | |
60 | ||
61 | /* Create an object cache C of N pointers to OTYPE. */ | |
62 | #define ocache_create(c, otype, n) \ | |
63 | do { \ | |
64 | (c).data = xmalloc((n) * sizeof (otype *)); \ | |
65 | (c).cs = (n); \ | |
66 | (c).nc = 0; \ | |
67 | } while (0) | |
68 | ||
69 | /* Destroy an object cache C. */ | |
70 | #define ocache_destroy(c) \ | |
71 | do { \ | |
72 | if ((c).data) \ | |
73 | xfree ((c).data); \ | |
74 | (c).data = 0; \ | |
75 | (c).cs = (c).nc = 0; \ | |
76 | } while (0) | |
77 | ||
78 | /* Free all cached items, which are pointers to OTYPE, in object cache C. */ | |
79 | #define ocache_flush(c, otype) \ | |
80 | do { \ | |
81 | while ((c).nc > 0) \ | |
82 | xfree (((otype **)((c).data))[--(c).nc]); \ | |
83 | } while (0) | |
84 | ||
85 | /* | |
86 | * Allocate a new item of type pointer to OTYPE, using data from object | |
87 | * cache C if any cached items exist, otherwise calling xmalloc. Return | |
88 | * the object in R. | |
89 | */ | |
90 | #define ocache_alloc(c, otype, r) \ | |
91 | do { \ | |
92 | if ((c).nc > 0) { \ | |
93 | (r) = (otype *)((otype **)((c).data))[--(c).nc]; \ | |
94 | } else \ | |
95 | (r) = (otype *)xmalloc (sizeof (otype)); \ | |
96 | } while (0) | |
97 | ||
98 | /* | |
99 | * Free an item R of type pointer to OTYPE, adding to object cache C if | |
100 | * there is room and calling xfree if the cache is full. If R is added | |
101 | * to the object cache, the contents are scrambled. | |
102 | */ | |
103 | #define ocache_free(c, otype, r) \ | |
104 | do { \ | |
105 | if ((c).nc < (c).cs) { \ | |
106 | OC_MEMSET ((r), 0xdf, sizeof(otype)); \ | |
107 | ((otype **)((c).data))[(c).nc++] = (r); \ | |
108 | } else \ | |
109 | xfree (r); \ | |
110 | } while (0) | |
111 | ||
112 | /* | |
113 | * One may declare and use an object cache as (for instance): | |
114 | * | |
115 | * sh_obj_cache_t wdcache = {0, 0, 0}; | |
116 | * sh_obj_cache_t wlcache = {0, 0, 0}; | |
117 | * | |
118 | * ocache_create(wdcache, WORD_DESC, 30); | |
119 | * ocache_create(wlcache, WORD_LIST, 30); | |
120 | * | |
121 | * WORD_DESC *wd; | |
122 | * ocache_alloc (wdcache, WORD_DESC, wd); | |
123 | * | |
124 | * WORD_LIST *wl; | |
125 | * ocache_alloc (wlcache, WORD_LIST, wl); | |
126 | * | |
127 | * ocache_free(wdcache, WORD_DESC, wd); | |
128 | * ocache_free(wlcache, WORD_LIST, wl); | |
129 | * | |
130 | * The use is almost arbitrary. | |
131 | */ | |
132 | ||
133 | #endif /* _OCACHE_H */ |