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1 | /* -*-c-*- |
2 | * |
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3 | * $Id: sub.h,v 1.7 2003/10/12 14:44:46 mdw Exp $ |
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4 | * |
5 | * Allocation of known-size blocks |
6 | * |
7 | * (c) 1998 Straylight/Edgeware |
8 | */ |
9 | |
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10 | /*----- Licensing notice --------------------------------------------------* |
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11 | * |
12 | * This file is part of the mLib utilities library. |
13 | * |
14 | * mLib is free software; you can redistribute it and/or modify |
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15 | * it under the terms of the GNU Library General Public License as |
16 | * published by the Free Software Foundation; either version 2 of the |
17 | * License, or (at your option) any later version. |
18 | * |
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19 | * mLib is distributed in the hope that it will be useful, |
20 | * but WITHOUT ANY WARRANTY; without even the implied warranty of |
21 | * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the |
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22 | * GNU Library General Public License for more details. |
23 | * |
24 | * You should have received a copy of the GNU Library General Public |
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25 | * License along with mLib; if not, write to the Free |
26 | * Software Foundation, Inc., 59 Temple Place - Suite 330, Boston, |
27 | * MA 02111-1307, USA. |
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28 | */ |
29 | |
30 | /*----- Revision history --------------------------------------------------* |
31 | * |
32 | * $Log: sub.h,v $ |
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33 | * Revision 1.7 2003/10/12 14:44:46 mdw |
34 | * Various fixes. |
35 | * |
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36 | * Revision 1.6 2000/06/17 10:35:51 mdw |
37 | * Major overhaul for arena support. |
38 | * |
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39 | * Revision 1.5 1999/12/10 23:42:04 mdw |
40 | * Change header file guard names. |
41 | * |
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42 | * Revision 1.4 1999/05/13 22:48:55 mdw |
43 | * Change `-ise' to `-ize' throughout. |
44 | * |
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45 | * Revision 1.3 1999/05/06 19:51:35 mdw |
46 | * Reformatted the LGPL notice a little bit. |
47 | * |
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48 | * Revision 1.2 1999/05/05 18:50:31 mdw |
49 | * Change licensing conditions to LGPL. |
50 | * |
51 | * Revision 1.1.1.1 1998/06/17 23:44:42 mdw |
52 | * Initial version of mLib |
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53 | * |
54 | */ |
55 | |
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56 | #ifndef MLIB_SUB_H |
57 | #define MLIB_SUB_H |
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58 | |
59 | #ifdef __cplusplus |
60 | extern "C" { |
61 | #endif |
62 | |
63 | /*----- Required header files ---------------------------------------------*/ |
64 | |
65 | #include <stdlib.h> |
66 | |
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67 | #ifndef MLIB_ALIGN_H |
68 | # include "align.h" |
69 | #endif |
70 | |
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71 | #ifndef MLIB_ARENA_H |
72 | # include "arena.h" |
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73 | #endif |
74 | |
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75 | /*----- Configuration and tuning ------------------------------------------*/ |
76 | |
77 | /* --- The largest block I'll handle here --- * |
78 | * |
79 | * Anything larger will be handed on to the underlying @alloc@. |
80 | */ |
81 | |
82 | #define SUB_MAXBIN 256 |
83 | |
84 | /* --- Preferred chunk size --- * |
85 | * |
86 | * When a bin is empty, I'll allocate a large chunk of approximately this |
87 | * size and divvy it up into small bin-sized blocks. |
88 | */ |
89 | |
90 | #define SUB_CHUNK 4096 |
91 | |
92 | /*----- Other useful macros -----------------------------------------------*/ |
93 | |
94 | /* --- The granularity of bin buffers --- * |
95 | * |
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96 | * All blocks allocated by the binner are a multiple of this size. |
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97 | */ |
98 | |
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99 | #define SUB_GRANULE sizeof(union align) |
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100 | |
101 | /* --- Finding the right bin for a given size --- * |
102 | * |
103 | * This chooses the correct bin for an allocation. Input is the size of |
104 | * block wanted; result is the bin index. |
105 | */ |
106 | |
107 | #define SUB_BIN(x) (((x) + SUB_GRANULE - 1) / SUB_GRANULE) |
108 | |
109 | /* --- Convert a bin back to the block size --- * |
110 | * |
111 | * This gives the size of block contained in a given bin. |
112 | */ |
113 | |
114 | #define SUB_BINSZ(x) ((x) * SUB_GRANULE) |
115 | |
116 | /* --- Number of bins required --- */ |
117 | |
118 | #define SUB_BINS (SUB_MAXBIN / SUB_GRANULE + 1) |
119 | |
120 | /*----- Data structures ---------------------------------------------------*/ |
121 | |
122 | typedef struct subarena { |
123 | arena *a; |
124 | void *bin[SUB_BINS]; |
125 | } subarena; |
126 | |
127 | /*----- Global variables --------------------------------------------------*/ |
128 | |
129 | extern subarena sub_global; |
130 | |
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131 | /*----- Functions provided ------------------------------------------------*/ |
132 | |
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133 | /* --- @subarena_create@ --- * |
134 | * |
135 | * Arguments: @subarena *s@ = pointer to arena to initialize |
136 | * @arena *a@ = pointer to underlying arena block |
137 | * |
138 | * Returns: --- |
139 | * |
140 | * Use: Initialize a suballocation arena based on an underlying large |
141 | * blocks arena. |
142 | */ |
143 | |
144 | extern void subarena_create(subarena */*s*/, arena */*a*/); |
145 | |
146 | /* --- @subarena_destroy@ --- * |
147 | * |
148 | * Arguments: @subarena *s@ = pointer to arena to destroy |
149 | * |
150 | * Returns: --- |
151 | * |
152 | * Use: Destroys a suballocation arena, freeing all of the memory it |
153 | * contains back to the underlying large blocks arena. |
154 | */ |
155 | |
156 | extern void subarena_destroy(subarena */*s*/); |
157 | |
158 | /* --- @subarena_alloc@ --- * |
159 | * |
160 | * Arguments: @subarena *s@ = pointer to arena |
161 | * @size_t s@ = size of chunk wanted |
162 | * |
163 | * Returns: Pointer to a block at least as large as the one wanted. |
164 | * |
165 | * Use: Allocates a small block of memory from the given pool. The |
166 | * exception @EXC_NOMEM@ is raised if the underlying arena is |
167 | * full. |
168 | */ |
169 | |
170 | extern void *subarena_alloc(subarena */*s*/, size_t /*sz*/); |
171 | |
172 | /* --- @subarena_free@ --- * |
173 | * |
174 | * Arguments: @subarena *s@ = pointer to arena |
175 | * @void *p@ = address of block to free |
176 | * @size_t s@ = size of block |
177 | * |
178 | * Returns: --- |
179 | * |
180 | * Use: Frees a block allocated by @subarena_alloc@. |
181 | */ |
182 | |
183 | extern void subarena_free(subarena */*s*/, void */*p*/, size_t /*sz*/); |
184 | |
185 | /* --- @A_CREATE@ --- * |
186 | * |
187 | * Arguments: @subarena *s@ = pointer to arena |
188 | * @type@ = type of object required; must be passable to |
189 | * @sizeof@ |
190 | * |
191 | * Returns: Pointer to a block sufficiently big to hold an object of the |
192 | * named type. |
193 | * |
194 | * Use: Allocates a block of the required type. |
195 | */ |
196 | |
197 | #define A_CREATE(a, type) subarena_alloc((a), sizeof(type)) |
198 | |
199 | /* --- @A_DESTROY@ --- * |
200 | * |
201 | * Arguments: @subarena *s@ = pointer to arena |
202 | * @void *p@ = pointer to an object |
203 | * |
204 | * Returns: --- |
205 | * |
206 | * Use: Frees the thing pointed to by @p@. |
207 | */ |
208 | |
209 | #define A_DESTROY(a, p) subarena_free((a), (p), sizeof(*p)) |
210 | |
211 | /*----- Shortcuts for the global pool -------------------------------------*/ |
212 | |
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213 | /* --- @sub_alloc@ --- * |
214 | * |
215 | * Arguments: @size_t s@ = size of chunk wanted |
216 | * |
217 | * Returns: Pointer to a block at least as large as the one wanted. |
218 | * |
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219 | * Use: Allocates a small block of memory from the @sub_global@ pool. |
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220 | */ |
221 | |
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222 | extern void *sub_alloc(size_t /*sz*/); |
223 | #define sub_alloc(sz) subarena_alloc(&sub_global, (sz)) |
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224 | |
225 | /* --- @sub_free@ --- * |
226 | * |
227 | * Arguments: @void *p@ = address of block to free |
228 | * @size_t s@ = size of block |
229 | * |
230 | * Returns: --- |
231 | * |
232 | * Use: Frees a block allocated by @sub_alloc@. |
233 | */ |
234 | |
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235 | extern void sub_free(void */*p*/, size_t /*sz*/); |
236 | #define sub_free(p, sz) subarena_free(&sub_global, (p), (sz)) |
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237 | |
238 | /* --- @CREATE@ --- * |
239 | * |
240 | * Arguments: @type@ = type of object required; must be passable to |
241 | * @sizeof@ |
242 | * |
243 | * Returns: Pointer to a block sufficiently big to hold an object of the |
244 | * named type. |
245 | * |
246 | * Use: Allocates a block of the required type. |
247 | */ |
248 | |
249 | #define CREATE(type) sub_alloc(sizeof(type)) |
250 | |
251 | /* --- @DESTROY@ --- * |
252 | * |
253 | * Arguments: @void *p@ = pointer to an object |
254 | * |
255 | * Returns: --- |
256 | * |
257 | * Use: Frees the thing pointed to by @p@. |
258 | */ |
259 | |
260 | #define DESTROY(p) sub_free(p, sizeof(*p)) |
261 | |
262 | /* --- @sub_init@ --- * |
263 | * |
264 | * Arguments: --- |
265 | * |
266 | * Returns: --- |
267 | * |
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268 | * Use: Initializes the magic allocator. This is no longer |
269 | * necessary. |
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270 | */ |
271 | |
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272 | extern void sub_init(void); |
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273 | |
274 | /*----- That's all, folks -------------------------------------------------*/ |
275 | |
276 | #ifdef __cplusplus |
277 | } |
278 | #endif |
279 | |
280 | #endif |