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1 | /* -*-c-*- |
2 | * |
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3 | * $Id: sub.h,v 1.8 2004/04/08 01:36:13 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 | |
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30 | #ifndef MLIB_SUB_H |
31 | #define MLIB_SUB_H |
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32 | |
33 | #ifdef __cplusplus |
34 | extern "C" { |
35 | #endif |
36 | |
37 | /*----- Required header files ---------------------------------------------*/ |
38 | |
39 | #include <stdlib.h> |
40 | |
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41 | #ifndef MLIB_ALIGN_H |
42 | # include "align.h" |
43 | #endif |
44 | |
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45 | #ifndef MLIB_ARENA_H |
46 | # include "arena.h" |
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47 | #endif |
48 | |
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49 | /*----- Configuration and tuning ------------------------------------------*/ |
50 | |
51 | /* --- The largest block I'll handle here --- * |
52 | * |
53 | * Anything larger will be handed on to the underlying @alloc@. |
54 | */ |
55 | |
56 | #define SUB_MAXBIN 256 |
57 | |
58 | /* --- Preferred chunk size --- * |
59 | * |
60 | * When a bin is empty, I'll allocate a large chunk of approximately this |
61 | * size and divvy it up into small bin-sized blocks. |
62 | */ |
63 | |
64 | #define SUB_CHUNK 4096 |
65 | |
66 | /*----- Other useful macros -----------------------------------------------*/ |
67 | |
68 | /* --- The granularity of bin buffers --- * |
69 | * |
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70 | * All blocks allocated by the binner are a multiple of this size. |
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71 | */ |
72 | |
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73 | #define SUB_GRANULE sizeof(union align) |
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74 | |
75 | /* --- Finding the right bin for a given size --- * |
76 | * |
77 | * This chooses the correct bin for an allocation. Input is the size of |
78 | * block wanted; result is the bin index. |
79 | */ |
80 | |
81 | #define SUB_BIN(x) (((x) + SUB_GRANULE - 1) / SUB_GRANULE) |
82 | |
83 | /* --- Convert a bin back to the block size --- * |
84 | * |
85 | * This gives the size of block contained in a given bin. |
86 | */ |
87 | |
88 | #define SUB_BINSZ(x) ((x) * SUB_GRANULE) |
89 | |
90 | /* --- Number of bins required --- */ |
91 | |
92 | #define SUB_BINS (SUB_MAXBIN / SUB_GRANULE + 1) |
93 | |
94 | /*----- Data structures ---------------------------------------------------*/ |
95 | |
96 | typedef struct subarena { |
97 | arena *a; |
98 | void *bin[SUB_BINS]; |
99 | } subarena; |
100 | |
101 | /*----- Global variables --------------------------------------------------*/ |
102 | |
103 | extern subarena sub_global; |
104 | |
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105 | /*----- Functions provided ------------------------------------------------*/ |
106 | |
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107 | /* --- @subarena_create@ --- * |
108 | * |
109 | * Arguments: @subarena *s@ = pointer to arena to initialize |
110 | * @arena *a@ = pointer to underlying arena block |
111 | * |
112 | * Returns: --- |
113 | * |
114 | * Use: Initialize a suballocation arena based on an underlying large |
115 | * blocks arena. |
116 | */ |
117 | |
118 | extern void subarena_create(subarena */*s*/, arena */*a*/); |
119 | |
120 | /* --- @subarena_destroy@ --- * |
121 | * |
122 | * Arguments: @subarena *s@ = pointer to arena to destroy |
123 | * |
124 | * Returns: --- |
125 | * |
126 | * Use: Destroys a suballocation arena, freeing all of the memory it |
127 | * contains back to the underlying large blocks arena. |
128 | */ |
129 | |
130 | extern void subarena_destroy(subarena */*s*/); |
131 | |
132 | /* --- @subarena_alloc@ --- * |
133 | * |
134 | * Arguments: @subarena *s@ = pointer to arena |
135 | * @size_t s@ = size of chunk wanted |
136 | * |
137 | * Returns: Pointer to a block at least as large as the one wanted. |
138 | * |
139 | * Use: Allocates a small block of memory from the given pool. The |
140 | * exception @EXC_NOMEM@ is raised if the underlying arena is |
141 | * full. |
142 | */ |
143 | |
144 | extern void *subarena_alloc(subarena */*s*/, size_t /*sz*/); |
145 | |
146 | /* --- @subarena_free@ --- * |
147 | * |
148 | * Arguments: @subarena *s@ = pointer to arena |
149 | * @void *p@ = address of block to free |
150 | * @size_t s@ = size of block |
151 | * |
152 | * Returns: --- |
153 | * |
154 | * Use: Frees a block allocated by @subarena_alloc@. |
155 | */ |
156 | |
157 | extern void subarena_free(subarena */*s*/, void */*p*/, size_t /*sz*/); |
158 | |
159 | /* --- @A_CREATE@ --- * |
160 | * |
161 | * Arguments: @subarena *s@ = pointer to arena |
162 | * @type@ = type of object required; must be passable to |
163 | * @sizeof@ |
164 | * |
165 | * Returns: Pointer to a block sufficiently big to hold an object of the |
166 | * named type. |
167 | * |
168 | * Use: Allocates a block of the required type. |
169 | */ |
170 | |
171 | #define A_CREATE(a, type) subarena_alloc((a), sizeof(type)) |
172 | |
173 | /* --- @A_DESTROY@ --- * |
174 | * |
175 | * Arguments: @subarena *s@ = pointer to arena |
176 | * @void *p@ = pointer to an object |
177 | * |
178 | * Returns: --- |
179 | * |
180 | * Use: Frees the thing pointed to by @p@. |
181 | */ |
182 | |
183 | #define A_DESTROY(a, p) subarena_free((a), (p), sizeof(*p)) |
184 | |
185 | /*----- Shortcuts for the global pool -------------------------------------*/ |
186 | |
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187 | /* --- @sub_alloc@ --- * |
188 | * |
189 | * Arguments: @size_t s@ = size of chunk wanted |
190 | * |
191 | * Returns: Pointer to a block at least as large as the one wanted. |
192 | * |
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193 | * Use: Allocates a small block of memory from the @sub_global@ pool. |
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194 | */ |
195 | |
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196 | extern void *sub_alloc(size_t /*sz*/); |
197 | #define sub_alloc(sz) subarena_alloc(&sub_global, (sz)) |
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198 | |
199 | /* --- @sub_free@ --- * |
200 | * |
201 | * Arguments: @void *p@ = address of block to free |
202 | * @size_t s@ = size of block |
203 | * |
204 | * Returns: --- |
205 | * |
206 | * Use: Frees a block allocated by @sub_alloc@. |
207 | */ |
208 | |
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209 | extern void sub_free(void */*p*/, size_t /*sz*/); |
210 | #define sub_free(p, sz) subarena_free(&sub_global, (p), (sz)) |
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211 | |
212 | /* --- @CREATE@ --- * |
213 | * |
214 | * Arguments: @type@ = type of object required; must be passable to |
215 | * @sizeof@ |
216 | * |
217 | * Returns: Pointer to a block sufficiently big to hold an object of the |
218 | * named type. |
219 | * |
220 | * Use: Allocates a block of the required type. |
221 | */ |
222 | |
223 | #define CREATE(type) sub_alloc(sizeof(type)) |
224 | |
225 | /* --- @DESTROY@ --- * |
226 | * |
227 | * Arguments: @void *p@ = pointer to an object |
228 | * |
229 | * Returns: --- |
230 | * |
231 | * Use: Frees the thing pointed to by @p@. |
232 | */ |
233 | |
234 | #define DESTROY(p) sub_free(p, sizeof(*p)) |
235 | |
236 | /* --- @sub_init@ --- * |
237 | * |
238 | * Arguments: --- |
239 | * |
240 | * Returns: --- |
241 | * |
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242 | * Use: Initializes the magic allocator. This is no longer |
243 | * necessary. |
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244 | */ |
245 | |
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246 | extern void sub_init(void); |
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247 | |
248 | /*----- That's all, folks -------------------------------------------------*/ |
249 | |
250 | #ifdef __cplusplus |
251 | } |
252 | #endif |
253 | |
254 | #endif |