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1 | /* -*-c-*- |
2 | * |
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3 | * $Id: darray.c,v 1.5 2000/06/17 10:37:39 mdw Exp $ |
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4 | * |
5 | * Dynamically growing dense arrays |
6 | * |
7 | * (c) 1999 Straylight/Edgeware |
8 | */ |
9 | |
10 | /*----- Licensing notice --------------------------------------------------* |
11 | * |
12 | * This file is part of the mLib utilities library. |
13 | * |
14 | * mLib is free software; you can redistribute it and/or modify |
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 | * |
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 |
22 | * GNU Library General Public License for more details. |
23 | * |
24 | * You should have received a copy of the GNU Library General Public |
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. |
28 | */ |
29 | |
30 | /*----- Revision history --------------------------------------------------* |
31 | * |
32 | * $Log: darray.c,v $ |
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33 | * Revision 1.5 2000/06/17 10:37:39 mdw |
34 | * Add support for arena management. |
35 | * |
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36 | * Revision 1.4 1999/11/06 12:40:45 mdw |
37 | * Minor changes to allocation strategy. |
38 | * |
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39 | * Revision 1.3 1999/10/29 22:59:22 mdw |
40 | * New array adjustment macros for unsigned arguments. |
41 | * |
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42 | * Revision 1.2 1999/10/28 22:05:28 mdw |
43 | * Modify and debug allocation routines. |
44 | * |
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45 | * Revision 1.1 1999/10/22 22:37:26 mdw |
46 | * New dynamic array implementation replaces `dynarray.h'. |
47 | * |
48 | */ |
49 | |
50 | /*----- Header files ------------------------------------------------------*/ |
51 | |
52 | #include <stdio.h> |
53 | #include <string.h> |
54 | #include <stdlib.h> |
55 | |
56 | #include "alloc.h" |
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57 | #include "arena.h" |
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58 | #include "darray.h" |
59 | |
60 | /*----- Magic numbers -----------------------------------------------------*/ |
61 | |
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62 | #define DA_INITSZ 16 /* Default size for new array */ |
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63 | #define DA_SLOTS 8 /* Number of preshifted slots */ |
64 | |
65 | /*----- Main code ---------------------------------------------------------*/ |
66 | |
67 | /* --- @da_ensure@ --- * |
68 | * |
69 | * Arguments: @da_base *b@ = pointer to array base structure |
70 | * @void *v@ = pointer to array vector |
71 | * @size_t sz@ = size of individual array elements |
72 | * @size_t n@ = number of items required at the end |
73 | * |
74 | * Returns: Pointer to newly allocated or adjusted array vector. |
75 | * |
76 | * Use: Extends a dynamic array to accommodate a number of new items |
77 | * at its end. This function is a helper for the @DA_ENSURE@ |
78 | * macro, which should be used by preference. |
79 | */ |
80 | |
81 | void *da_ensure(da_base *b, void *v, size_t sz, size_t n) |
82 | { |
83 | size_t rq = n + b->len; |
84 | char *p = v, *q; |
85 | size_t nsz; |
86 | size_t slots; |
87 | |
88 | /* --- Make sure there's something which needs doing --- * |
89 | * |
90 | * If there's enough space already then return immediately. |
91 | */ |
92 | |
93 | if (rq < b->sz) |
94 | return (p); |
95 | |
96 | /* --- Compute a number of `unshift' slots --- * |
97 | * |
98 | * When returning from this function, the offset will be set to @slots@. |
99 | * If @unshift@ is zero, there's no point in reserving slots. Otherwise |
100 | * choose a power of two greater than @unshift@, with a minimum of |
101 | * @DA_SLOTS@. Then add the number of slots to the requirement. |
102 | */ |
103 | |
104 | if (!b->unshift) |
105 | slots = 0; |
106 | else { |
107 | slots = DA_SLOTS; |
108 | while (slots < b->unshift) |
109 | slots <<= 1; |
110 | } |
111 | rq += slots; |
112 | |
113 | /* --- Maybe just shunt data around a bit --- * |
114 | * |
115 | * If the vector is large enough, then theoretically we could cope by |
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116 | * moving the objects about in their existing storage. It's not worth |
117 | * bothering if there's not actually double the amount of space I need. |
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118 | */ |
119 | |
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120 | if (rq * 2 < b->sz + b->off) { |
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121 | q = p - (b->off - slots) * sz; |
122 | memmove(q, p, b->len * sz); |
123 | b->sz += b->off - slots; |
124 | b->off = slots; |
125 | b->unshift = b->push = 0; |
126 | return (q); |
127 | } |
128 | |
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129 | /* --- Decide on a new size --- * |
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130 | * |
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131 | * There's a minimum possible size for the array which is used if it's |
132 | * currently completely empty. Otherwise I choose the smallest power of |
133 | * two which is big enough, starting at double the current size. |
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134 | */ |
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135 | |
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136 | nsz = v ? b->sz + b->off : (DA_INITSZ >> 1); |
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137 | do nsz <<= 1; while (nsz < rq); |
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138 | |
139 | /* --- Reallocate the block --- * |
140 | * |
141 | * If I'm not changing the base offset then it's worth using @realloc@; |
142 | * otherwise there'll probably be two calls to @memcpy@ to shunt the data |
143 | * around so it's not worth bothering. |
144 | */ |
145 | |
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146 | if (p && slots == b->off) { |
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147 | q = x_realloc(b->a, p - b->off * sz, nsz * sz); |
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148 | q += slots * sz; |
149 | } else { |
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150 | q = x_alloc(b->a, nsz * sz); |
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151 | q += slots * sz; |
152 | if (p) { |
153 | memcpy(q, p, b->len * sz); |
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154 | x_free(b->a, p - b->off * sz); |
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155 | } |
156 | } |
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157 | |
158 | /* --- Fill in the other parts of the base structure --- */ |
159 | |
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160 | b->off = slots; |
161 | b->sz = nsz - slots; |
162 | b->unshift = b->push = 0; |
163 | return (q); |
164 | } |
165 | |
166 | /* --- @da_shunt@ --- * |
167 | * |
168 | * Arguments: @da_base *b@ = pointer to array base structure |
169 | * @void *v@ = pointer to array vector |
170 | * @size_t sz@ = size of the array elements |
171 | * @size_t n@ = number of items required at the start |
172 | * |
173 | * Returns: Pointer to appropriately bodged vector. |
174 | * |
175 | * Use: Extends an array to accommodate items inserted at its front. |
176 | * This function is a helper for the @DA_SHUNT@ macro, which |
177 | * should be used by preference. |
178 | */ |
179 | |
180 | void *da_shunt(da_base *b, void *v, size_t sz, size_t n) |
181 | { |
182 | size_t rq; |
183 | char *p = v, *q; |
184 | size_t nsz; |
185 | size_t slots; |
186 | |
187 | /* --- Make sure there's something which needs doing --- * |
188 | * |
189 | * If there's enough space already then return immediately. |
190 | */ |
191 | |
192 | if (n < b->off) |
193 | return (p); |
194 | |
195 | /* --- Compute a number of `push' slots --- * |
196 | * |
197 | * When returning from this function, there will be @slots@ free spaces at |
198 | * the end of the array. If @push@ is zero, there's no point in reserving |
199 | * slots. Otherwise choose a power of two greater than @push@, with a |
200 | * minimum of @DA_SLOTS@. To simplify matters, add the number of items |
201 | * already in the array to @slots@, and then add the number of slots to the |
202 | * requirement. |
203 | */ |
204 | |
205 | if (!b->push) |
206 | slots = 0; |
207 | else { |
208 | slots = DA_SLOTS; |
209 | while (slots < b->push) |
210 | slots <<= 1; |
211 | } |
212 | slots += b->len; |
213 | rq = n + slots; |
214 | |
215 | /* --- Maybe just shunt data around a bit --- * |
216 | * |
217 | * If the vector is large enough, then theoretically we could cope by |
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218 | * moving the objects about in their existing storage. Again, if there's |
219 | * not actually twice the space needed, reallocate the array. |
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220 | */ |
221 | |
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222 | if (rq * 2 < b->sz + b->off) { |
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223 | q = p + (b->sz - slots) * sz; |
224 | memmove(q, p, b->len * sz); |
225 | b->off += b->sz - slots; |
226 | b->sz = slots; |
227 | b->unshift = b->push = 0; |
228 | return (q); |
229 | } |
230 | |
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231 | /* --- Reallocate the array --- * |
232 | * |
233 | * The neat @realloc@ code doesn't need to be here: the offset changes |
234 | * almost all the time -- that's the whole point of this routine! |
235 | */ |
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236 | |
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237 | /* --- Decide on a new size --- * |
238 | * |
239 | * There's a minimum possible size for the array which is used if it's |
240 | * currently completely empty. Otherwise I choose the smallest power of |
241 | * two which is big enough, starting at double the current size. |
242 | */ |
243 | |
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244 | nsz = v ? b->sz + b->off : (DA_INITSZ >> 1); |
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245 | do nsz <<= 1; while (nsz < rq); |
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246 | |
247 | /* --- Reallocate the block --- * |
248 | * |
249 | * The neat @realloc@ code doesn't need to be here: the offset changes |
250 | * almost all the time -- that's the whole point of this routine! |
251 | */ |
252 | |
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253 | q = x_alloc(b->a, nsz * sz); |
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254 | q += (nsz - slots) * sz; |
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255 | if (p) { |
256 | memcpy(q, p, b->len * sz); |
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257 | x_free(b->a, p - b->off * sz); |
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258 | } |
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259 | |
260 | /* --- Fill in the other parts of the base structure --- */ |
261 | |
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262 | b->off = nsz - slots; |
263 | b->sz = slots; |
264 | b->unshift = b->push = 0; |
265 | return (q); |
266 | } |
267 | |
268 | /* --- @da_tidy@ --- * |
269 | * |
270 | * Arguments: @da_base *b@ = pointer to array base structure |
271 | * @void *v@ = pointer to vector |
272 | * @size_t sz@ = size of the array elements |
273 | * |
274 | * Returns: Newly allocated vector. |
275 | * |
276 | * Use: Minimizes the space occupied by an array. This function is a |
277 | * helper for the @DA_TIDY@ macro, which should be used by |
278 | * preference. |
279 | */ |
280 | |
281 | void *da_tidy(da_base *b, void *v, size_t sz) |
282 | { |
283 | char *p = v, *q; |
284 | |
285 | b->unshift = b->push = 0; |
286 | |
287 | if (!p) |
288 | return (0); |
289 | if (b->sz == b->len && b->off == 0) |
290 | return (p); |
291 | |
292 | if (!b->len) { |
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293 | xfree(p - b->off * sz); |
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294 | return (0); |
295 | } |
296 | |
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297 | q = x_alloc(b->a, b->len * sz); |
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298 | memcpy(q, p, b->len * sz); |
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299 | x_free(b->a, p - b->off * sz); |
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300 | b->sz = b->len; |
301 | b->off = 0; |
302 | return (q); |
303 | } |
304 | |
305 | /* --- Note about testing --- * |
306 | * |
307 | * The test rig for this code is split into three parts. There's `da-gtest', |
308 | * which is a Perl script which generates a list of commands. The `da-ref' |
309 | * Perl script interprets these commands as operations on a Perl array. It's |
310 | * relatively conservatively written and believed to be reliable. The |
311 | * `da-test.c' file implements a command reader for the same syntax and |
312 | * performs the operations on an integer darray, producing output in the same |
313 | * format. To test darray, generate a command script with `da-gtest', pass |
314 | * it through both `da-ref' and `da-test' (the result of compiling |
315 | * da-test.c'), and compare the results. If they're not byte-for-byte |
316 | * identical, there's something wrong. |
317 | */ |
318 | |
319 | /*----- That's all, folks -------------------------------------------------*/ |