Commit | Line | Data |
---|---|---|
3745e24b | 1 | /* -*-c-*- |
2 | * | |
3745e24b | 3 | * Dynamically growing dense arrays |
4 | * | |
5 | * (c) 1999 Straylight/Edgeware | |
6 | */ | |
7 | ||
d4efbcd9 | 8 | /*----- Licensing notice --------------------------------------------------* |
3745e24b | 9 | * |
10 | * This file is part of the mLib utilities library. | |
11 | * | |
12 | * mLib is free software; you can redistribute it and/or modify | |
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 | * |
3745e24b | 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 | |
20 | * GNU Library General Public License for more details. | |
d4efbcd9 | 21 | * |
3745e24b | 22 | * You should have received a copy of the GNU Library General Public |
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. | |
26 | */ | |
27 | ||
3745e24b | 28 | /*----- Header files ------------------------------------------------------*/ |
29 | ||
30 | #include <stdio.h> | |
31 | #include <string.h> | |
32 | #include <stdlib.h> | |
33 | ||
34 | #include "alloc.h" | |
20eb516f | 35 | #include "arena.h" |
3745e24b | 36 | #include "darray.h" |
adec5584 | 37 | #include "growbuf.h" |
3745e24b | 38 | |
39 | /*----- Magic numbers -----------------------------------------------------*/ | |
40 | ||
f8509853 | 41 | #define DA_INITSZ 16 /* Default size for new array */ |
3745e24b | 42 | #define DA_SLOTS 8 /* Number of preshifted slots */ |
43 | ||
44 | /*----- Main code ---------------------------------------------------------*/ | |
45 | ||
46 | /* --- @da_ensure@ --- * | |
47 | * | |
48 | * Arguments: @da_base *b@ = pointer to array base structure | |
49 | * @void *v@ = pointer to array vector | |
50 | * @size_t sz@ = size of individual array elements | |
51 | * @size_t n@ = number of items required at the end | |
52 | * | |
53 | * Returns: Pointer to newly allocated or adjusted array vector. | |
54 | * | |
55 | * Use: Extends a dynamic array to accommodate a number of new items | |
56 | * at its end. This function is a helper for the @DA_ENSURE@ | |
57 | * macro, which should be used by preference. | |
58 | */ | |
59 | ||
60 | void *da_ensure(da_base *b, void *v, size_t sz, size_t n) | |
61 | { | |
62 | size_t rq = n + b->len; | |
63 | char *p = v, *q; | |
64 | size_t nsz; | |
65 | size_t slots; | |
66 | ||
67 | /* --- Make sure there's something which needs doing --- * | |
68 | * | |
69 | * If there's enough space already then return immediately. | |
70 | */ | |
71 | ||
72 | if (rq < b->sz) | |
73 | return (p); | |
74 | ||
75 | /* --- Compute a number of `unshift' slots --- * | |
76 | * | |
77 | * When returning from this function, the offset will be set to @slots@. | |
78 | * If @unshift@ is zero, there's no point in reserving slots. Otherwise | |
79 | * choose a power of two greater than @unshift@, with a minimum of | |
80 | * @DA_SLOTS@. Then add the number of slots to the requirement. | |
81 | */ | |
82 | ||
83 | if (!b->unshift) | |
84 | slots = 0; | |
85 | else { | |
86 | slots = DA_SLOTS; | |
87 | while (slots < b->unshift) | |
88 | slots <<= 1; | |
89 | } | |
90 | rq += slots; | |
91 | ||
92 | /* --- Maybe just shunt data around a bit --- * | |
93 | * | |
94 | * If the vector is large enough, then theoretically we could cope by | |
c6e5bbae | 95 | * moving the objects about in their existing storage. It's not worth |
96 | * bothering if there's not actually double the amount of space I need. | |
3745e24b | 97 | */ |
98 | ||
c6e5bbae | 99 | if (rq * 2 < b->sz + b->off) { |
3745e24b | 100 | q = p - (b->off - slots) * sz; |
101 | memmove(q, p, b->len * sz); | |
102 | b->sz += b->off - slots; | |
103 | b->off = slots; | |
104 | b->unshift = b->push = 0; | |
105 | return (q); | |
106 | } | |
107 | ||
c6e5bbae | 108 | /* --- Decide on a new size --- * |
85bb21f7 | 109 | * |
c6e5bbae | 110 | * There's a minimum possible size for the array which is used if it's |
111 | * currently completely empty. Otherwise I choose the smallest power of | |
112 | * two which is big enough, starting at double the current size. | |
85bb21f7 | 113 | */ |
3745e24b | 114 | |
adec5584 MW |
115 | nsz = b->sz + b->off; |
116 | GROWBUF_SIZE(nsz, rq, DA_INITSZ, sz); | |
c6e5bbae | 117 | |
118 | /* --- Reallocate the block --- * | |
119 | * | |
120 | * If I'm not changing the base offset then it's worth using @realloc@; | |
121 | * otherwise there'll probably be two calls to @memcpy@ to shunt the data | |
122 | * around so it's not worth bothering. | |
123 | */ | |
124 | ||
85bb21f7 | 125 | if (p && slots == b->off) { |
b5ea4de3 | 126 | q = x_realloc(b->a, p - b->off * sz, nsz * sz, b->sz + b->off); |
85bb21f7 | 127 | q += slots * sz; |
128 | } else { | |
20eb516f | 129 | q = x_alloc(b->a, nsz * sz); |
85bb21f7 | 130 | q += slots * sz; |
131 | if (p) { | |
132 | memcpy(q, p, b->len * sz); | |
20eb516f | 133 | x_free(b->a, p - b->off * sz); |
85bb21f7 | 134 | } |
135 | } | |
c6e5bbae | 136 | |
137 | /* --- Fill in the other parts of the base structure --- */ | |
138 | ||
3745e24b | 139 | b->off = slots; |
140 | b->sz = nsz - slots; | |
141 | b->unshift = b->push = 0; | |
142 | return (q); | |
143 | } | |
144 | ||
145 | /* --- @da_shunt@ --- * | |
146 | * | |
147 | * Arguments: @da_base *b@ = pointer to array base structure | |
148 | * @void *v@ = pointer to array vector | |
149 | * @size_t sz@ = size of the array elements | |
150 | * @size_t n@ = number of items required at the start | |
151 | * | |
152 | * Returns: Pointer to appropriately bodged vector. | |
153 | * | |
154 | * Use: Extends an array to accommodate items inserted at its front. | |
155 | * This function is a helper for the @DA_SHUNT@ macro, which | |
156 | * should be used by preference. | |
157 | */ | |
158 | ||
159 | void *da_shunt(da_base *b, void *v, size_t sz, size_t n) | |
160 | { | |
161 | size_t rq; | |
162 | char *p = v, *q; | |
163 | size_t nsz; | |
164 | size_t slots; | |
165 | ||
166 | /* --- Make sure there's something which needs doing --- * | |
167 | * | |
168 | * If there's enough space already then return immediately. | |
169 | */ | |
170 | ||
171 | if (n < b->off) | |
172 | return (p); | |
173 | ||
174 | /* --- Compute a number of `push' slots --- * | |
175 | * | |
176 | * When returning from this function, there will be @slots@ free spaces at | |
177 | * the end of the array. If @push@ is zero, there's no point in reserving | |
178 | * slots. Otherwise choose a power of two greater than @push@, with a | |
179 | * minimum of @DA_SLOTS@. To simplify matters, add the number of items | |
180 | * already in the array to @slots@, and then add the number of slots to the | |
181 | * requirement. | |
182 | */ | |
183 | ||
184 | if (!b->push) | |
185 | slots = 0; | |
186 | else { | |
187 | slots = DA_SLOTS; | |
188 | while (slots < b->push) | |
189 | slots <<= 1; | |
190 | } | |
191 | slots += b->len; | |
192 | rq = n + slots; | |
193 | ||
194 | /* --- Maybe just shunt data around a bit --- * | |
195 | * | |
196 | * If the vector is large enough, then theoretically we could cope by | |
c6e5bbae | 197 | * moving the objects about in their existing storage. Again, if there's |
198 | * not actually twice the space needed, reallocate the array. | |
3745e24b | 199 | */ |
200 | ||
c6e5bbae | 201 | if (rq * 2 < b->sz + b->off) { |
3745e24b | 202 | q = p + (b->sz - slots) * sz; |
203 | memmove(q, p, b->len * sz); | |
204 | b->off += b->sz - slots; | |
205 | b->sz = slots; | |
206 | b->unshift = b->push = 0; | |
207 | return (q); | |
208 | } | |
209 | ||
85bb21f7 | 210 | /* --- Reallocate the array --- * |
211 | * | |
212 | * The neat @realloc@ code doesn't need to be here: the offset changes | |
213 | * almost all the time -- that's the whole point of this routine! | |
214 | */ | |
3745e24b | 215 | |
c6e5bbae | 216 | /* --- Decide on a new size --- * |
217 | * | |
218 | * There's a minimum possible size for the array which is used if it's | |
219 | * currently completely empty. Otherwise I choose the smallest power of | |
220 | * two which is big enough, starting at double the current size. | |
221 | */ | |
222 | ||
adec5584 MW |
223 | nsz = b->sz + b->off; |
224 | GROWBUF_SIZE(nsz, rq, DA_INITSZ, sz); | |
c6e5bbae | 225 | |
226 | /* --- Reallocate the block --- * | |
227 | * | |
228 | * The neat @realloc@ code doesn't need to be here: the offset changes | |
229 | * almost all the time -- that's the whole point of this routine! | |
230 | */ | |
231 | ||
20eb516f | 232 | q = x_alloc(b->a, nsz * sz); |
3745e24b | 233 | q += (nsz - slots) * sz; |
85bb21f7 | 234 | if (p) { |
235 | memcpy(q, p, b->len * sz); | |
20eb516f | 236 | x_free(b->a, p - b->off * sz); |
85bb21f7 | 237 | } |
c6e5bbae | 238 | |
239 | /* --- Fill in the other parts of the base structure --- */ | |
d4efbcd9 | 240 | |
3745e24b | 241 | b->off = nsz - slots; |
242 | b->sz = slots; | |
243 | b->unshift = b->push = 0; | |
244 | return (q); | |
245 | } | |
246 | ||
247 | /* --- @da_tidy@ --- * | |
248 | * | |
249 | * Arguments: @da_base *b@ = pointer to array base structure | |
250 | * @void *v@ = pointer to vector | |
251 | * @size_t sz@ = size of the array elements | |
252 | * | |
253 | * Returns: Newly allocated vector. | |
254 | * | |
255 | * Use: Minimizes the space occupied by an array. This function is a | |
256 | * helper for the @DA_TIDY@ macro, which should be used by | |
257 | * preference. | |
258 | */ | |
259 | ||
260 | void *da_tidy(da_base *b, void *v, size_t sz) | |
261 | { | |
262 | char *p = v, *q; | |
263 | ||
264 | b->unshift = b->push = 0; | |
265 | ||
266 | if (!p) | |
267 | return (0); | |
268 | if (b->sz == b->len && b->off == 0) | |
269 | return (p); | |
270 | ||
271 | if (!b->len) { | |
20eb516f | 272 | xfree(p - b->off * sz); |
3745e24b | 273 | return (0); |
274 | } | |
275 | ||
20eb516f | 276 | q = x_alloc(b->a, b->len * sz); |
3745e24b | 277 | memcpy(q, p, b->len * sz); |
20eb516f | 278 | x_free(b->a, p - b->off * sz); |
3745e24b | 279 | b->sz = b->len; |
280 | b->off = 0; | |
281 | return (q); | |
282 | } | |
283 | ||
284 | /* --- Note about testing --- * | |
285 | * | |
286 | * The test rig for this code is split into three parts. There's `da-gtest', | |
287 | * which is a Perl script which generates a list of commands. The `da-ref' | |
288 | * Perl script interprets these commands as operations on a Perl array. It's | |
289 | * relatively conservatively written and believed to be reliable. The | |
290 | * `da-test.c' file implements a command reader for the same syntax and | |
291 | * performs the operations on an integer darray, producing output in the same | |
292 | * format. To test darray, generate a command script with `da-gtest', pass | |
293 | * it through both `da-ref' and `da-test' (the result of compiling | |
294 | * da-test.c'), and compare the results. If they're not byte-for-byte | |
295 | * identical, there's something wrong. | |
296 | */ | |
297 | ||
298 | /*----- That's all, folks -------------------------------------------------*/ |