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0875b58f | 1 | /* -*-c-*- |
2 | * | |
0875b58f | 3 | * Allocation of known-size blocks |
4 | * | |
5 | * (c) 1998 Straylight/Edgeware | |
6 | */ | |
7 | ||
d4efbcd9 | 8 | /*----- Licensing notice --------------------------------------------------* |
0875b58f | 9 | * |
10 | * This file is part of the mLib utilities library. | |
11 | * | |
12 | * mLib is free software; you can redistribute it and/or modify | |
c846879c | 13 | * it under the terms of the GNU Library General Public License as |
14 | * published by the Free Software Foundation; either version 2 of the | |
15 | * License, or (at your option) any later version. | |
d4efbcd9 | 16 | * |
0875b58f | 17 | * mLib is distributed in the hope that it will be useful, |
18 | * but WITHOUT ANY WARRANTY; without even the implied warranty of | |
19 | * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the | |
c846879c | 20 | * GNU Library General Public License for more details. |
d4efbcd9 | 21 | * |
c846879c | 22 | * You should have received a copy of the GNU Library General Public |
0bd98442 | 23 | * License along with mLib; if not, write to the Free |
24 | * Software Foundation, Inc., 59 Temple Place - Suite 330, Boston, | |
25 | * MA 02111-1307, USA. | |
0875b58f | 26 | */ |
27 | ||
c6e0eaf0 | 28 | #ifndef MLIB_SUB_H |
29 | #define MLIB_SUB_H | |
0875b58f | 30 | |
31 | #ifdef __cplusplus | |
32 | extern "C" { | |
33 | #endif | |
34 | ||
35 | /*----- Required header files ---------------------------------------------*/ | |
36 | ||
37 | #include <stdlib.h> | |
38 | ||
c5775f49 | 39 | #ifndef MLIB_ALIGN_H |
40 | # include "align.h" | |
41 | #endif | |
42 | ||
0fd574c3 | 43 | #ifndef MLIB_ARENA_H |
44 | # include "arena.h" | |
0875b58f | 45 | #endif |
46 | ||
0fd574c3 | 47 | /*----- Configuration and tuning ------------------------------------------*/ |
48 | ||
49 | /* --- The largest block I'll handle here --- * | |
50 | * | |
51 | * Anything larger will be handed on to the underlying @alloc@. | |
52 | */ | |
53 | ||
54 | #define SUB_MAXBIN 256 | |
55 | ||
56 | /* --- Preferred chunk size --- * | |
57 | * | |
58 | * When a bin is empty, I'll allocate a large chunk of approximately this | |
59 | * size and divvy it up into small bin-sized blocks. | |
60 | */ | |
61 | ||
62 | #define SUB_CHUNK 4096 | |
63 | ||
64 | /*----- Other useful macros -----------------------------------------------*/ | |
65 | ||
66 | /* --- The granularity of bin buffers --- * | |
67 | * | |
c5775f49 | 68 | * All blocks allocated by the binner are a multiple of this size. |
0fd574c3 | 69 | */ |
70 | ||
c5775f49 | 71 | #define SUB_GRANULE sizeof(union align) |
0fd574c3 | 72 | |
73 | /* --- Finding the right bin for a given size --- * | |
74 | * | |
75 | * This chooses the correct bin for an allocation. Input is the size of | |
76 | * block wanted; result is the bin index. | |
77 | */ | |
78 | ||
79 | #define SUB_BIN(x) (((x) + SUB_GRANULE - 1) / SUB_GRANULE) | |
80 | ||
81 | /* --- Convert a bin back to the block size --- * | |
82 | * | |
83 | * This gives the size of block contained in a given bin. | |
84 | */ | |
85 | ||
86 | #define SUB_BINSZ(x) ((x) * SUB_GRANULE) | |
87 | ||
88 | /* --- Number of bins required --- */ | |
89 | ||
90 | #define SUB_BINS (SUB_MAXBIN / SUB_GRANULE + 1) | |
91 | ||
92 | /*----- Data structures ---------------------------------------------------*/ | |
93 | ||
94 | typedef struct subarena { | |
95 | arena *a; | |
96 | void *bin[SUB_BINS]; | |
97 | } subarena; | |
98 | ||
99 | /*----- Global variables --------------------------------------------------*/ | |
100 | ||
101 | extern subarena sub_global; | |
102 | ||
0875b58f | 103 | /*----- Functions provided ------------------------------------------------*/ |
104 | ||
0fd574c3 | 105 | /* --- @subarena_create@ --- * |
106 | * | |
107 | * Arguments: @subarena *s@ = pointer to arena to initialize | |
108 | * @arena *a@ = pointer to underlying arena block | |
109 | * | |
110 | * Returns: --- | |
111 | * | |
112 | * Use: Initialize a suballocation arena based on an underlying large | |
113 | * blocks arena. | |
114 | */ | |
115 | ||
116 | extern void subarena_create(subarena */*s*/, arena */*a*/); | |
117 | ||
118 | /* --- @subarena_destroy@ --- * | |
119 | * | |
120 | * Arguments: @subarena *s@ = pointer to arena to destroy | |
121 | * | |
122 | * Returns: --- | |
123 | * | |
124 | * Use: Destroys a suballocation arena, freeing all of the memory it | |
125 | * contains back to the underlying large blocks arena. | |
126 | */ | |
127 | ||
128 | extern void subarena_destroy(subarena */*s*/); | |
129 | ||
130 | /* --- @subarena_alloc@ --- * | |
131 | * | |
132 | * Arguments: @subarena *s@ = pointer to arena | |
133 | * @size_t s@ = size of chunk wanted | |
134 | * | |
d4efbcd9 | 135 | * Returns: Pointer to a block at least as large as the one wanted. |
0fd574c3 | 136 | * |
d4efbcd9 | 137 | * Use: Allocates a small block of memory from the given pool. The |
0fd574c3 | 138 | * exception @EXC_NOMEM@ is raised if the underlying arena is |
139 | * full. | |
140 | */ | |
141 | ||
142 | extern void *subarena_alloc(subarena */*s*/, size_t /*sz*/); | |
143 | ||
144 | /* --- @subarena_free@ --- * | |
145 | * | |
d4efbcd9 | 146 | * Arguments: @subarena *s@ = pointer to arena |
0fd574c3 | 147 | * @void *p@ = address of block to free |
d4efbcd9 | 148 | * @size_t s@ = size of block |
0fd574c3 | 149 | * |
d4efbcd9 | 150 | * Returns: --- |
0fd574c3 | 151 | * |
d4efbcd9 | 152 | * Use: Frees a block allocated by @subarena_alloc@. |
0fd574c3 | 153 | */ |
154 | ||
155 | extern void subarena_free(subarena */*s*/, void */*p*/, size_t /*sz*/); | |
156 | ||
157 | /* --- @A_CREATE@ --- * | |
158 | * | |
159 | * Arguments: @subarena *s@ = pointer to arena | |
160 | * @type@ = type of object required; must be passable to | |
161 | * @sizeof@ | |
162 | * | |
163 | * Returns: Pointer to a block sufficiently big to hold an object of the | |
164 | * named type. | |
165 | * | |
166 | * Use: Allocates a block of the required type. | |
167 | */ | |
168 | ||
169 | #define A_CREATE(a, type) subarena_alloc((a), sizeof(type)) | |
170 | ||
171 | /* --- @A_DESTROY@ --- * | |
172 | * | |
173 | * Arguments: @subarena *s@ = pointer to arena | |
174 | * @void *p@ = pointer to an object | |
175 | * | |
176 | * Returns: --- | |
177 | * | |
178 | * Use: Frees the thing pointed to by @p@. | |
179 | */ | |
180 | ||
181 | #define A_DESTROY(a, p) subarena_free((a), (p), sizeof(*p)) | |
182 | ||
183 | /*----- Shortcuts for the global pool -------------------------------------*/ | |
184 | ||
0875b58f | 185 | /* --- @sub_alloc@ --- * |
186 | * | |
d4efbcd9 | 187 | * Arguments: @size_t s@ = size of chunk wanted |
0875b58f | 188 | * |
d4efbcd9 | 189 | * Returns: Pointer to a block at least as large as the one wanted. |
0875b58f | 190 | * |
d4efbcd9 | 191 | * Use: Allocates a small block of memory from the @sub_global@ pool. |
0875b58f | 192 | */ |
193 | ||
0fd574c3 | 194 | extern void *sub_alloc(size_t /*sz*/); |
195 | #define sub_alloc(sz) subarena_alloc(&sub_global, (sz)) | |
0875b58f | 196 | |
197 | /* --- @sub_free@ --- * | |
198 | * | |
d4efbcd9 MW |
199 | * Arguments: @void *p@ = address of block to free |
200 | * @size_t s@ = size of block | |
0875b58f | 201 | * |
d4efbcd9 | 202 | * Returns: --- |
0875b58f | 203 | * |
d4efbcd9 | 204 | * Use: Frees a block allocated by @sub_alloc@. |
0875b58f | 205 | */ |
206 | ||
0fd574c3 | 207 | extern void sub_free(void */*p*/, size_t /*sz*/); |
208 | #define sub_free(p, sz) subarena_free(&sub_global, (p), (sz)) | |
0875b58f | 209 | |
210 | /* --- @CREATE@ --- * | |
211 | * | |
212 | * Arguments: @type@ = type of object required; must be passable to | |
213 | * @sizeof@ | |
214 | * | |
215 | * Returns: Pointer to a block sufficiently big to hold an object of the | |
216 | * named type. | |
217 | * | |
218 | * Use: Allocates a block of the required type. | |
219 | */ | |
220 | ||
221 | #define CREATE(type) sub_alloc(sizeof(type)) | |
222 | ||
223 | /* --- @DESTROY@ --- * | |
224 | * | |
225 | * Arguments: @void *p@ = pointer to an object | |
226 | * | |
227 | * Returns: --- | |
228 | * | |
229 | * Use: Frees the thing pointed to by @p@. | |
230 | */ | |
231 | ||
232 | #define DESTROY(p) sub_free(p, sizeof(*p)) | |
233 | ||
234 | /* --- @sub_init@ --- * | |
235 | * | |
d4efbcd9 | 236 | * Arguments: --- |
0875b58f | 237 | * |
d4efbcd9 | 238 | * Returns: --- |
0875b58f | 239 | * |
d4efbcd9 | 240 | * Use: Initializes the magic allocator. This is no longer |
0fd574c3 | 241 | * necessary. |
0875b58f | 242 | */ |
243 | ||
0fd574c3 | 244 | extern void sub_init(void); |
0875b58f | 245 | |
246 | /*----- That's all, folks -------------------------------------------------*/ | |
247 | ||
248 | #ifdef __cplusplus | |
249 | } | |
250 | #endif | |
251 | ||
252 | #endif |