3745e24b |
1 | /* -*-c-*- |
2 | * |
8656dc50 |
3 | * $Id: darray.c,v 1.7 2004/04/08 01:36:11 mdw Exp $ |
3745e24b |
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 | |
3745e24b |
30 | /*----- Header files ------------------------------------------------------*/ |
31 | |
32 | #include <stdio.h> |
33 | #include <string.h> |
34 | #include <stdlib.h> |
35 | |
36 | #include "alloc.h" |
20eb516f |
37 | #include "arena.h" |
3745e24b |
38 | #include "darray.h" |
39 | |
40 | /*----- Magic numbers -----------------------------------------------------*/ |
41 | |
f8509853 |
42 | #define DA_INITSZ 16 /* Default size for new array */ |
3745e24b |
43 | #define DA_SLOTS 8 /* Number of preshifted slots */ |
44 | |
45 | /*----- Main code ---------------------------------------------------------*/ |
46 | |
47 | /* --- @da_ensure@ --- * |
48 | * |
49 | * Arguments: @da_base *b@ = pointer to array base structure |
50 | * @void *v@ = pointer to array vector |
51 | * @size_t sz@ = size of individual array elements |
52 | * @size_t n@ = number of items required at the end |
53 | * |
54 | * Returns: Pointer to newly allocated or adjusted array vector. |
55 | * |
56 | * Use: Extends a dynamic array to accommodate a number of new items |
57 | * at its end. This function is a helper for the @DA_ENSURE@ |
58 | * macro, which should be used by preference. |
59 | */ |
60 | |
61 | void *da_ensure(da_base *b, void *v, size_t sz, size_t n) |
62 | { |
63 | size_t rq = n + b->len; |
64 | char *p = v, *q; |
65 | size_t nsz; |
66 | size_t slots; |
67 | |
68 | /* --- Make sure there's something which needs doing --- * |
69 | * |
70 | * If there's enough space already then return immediately. |
71 | */ |
72 | |
73 | if (rq < b->sz) |
74 | return (p); |
75 | |
76 | /* --- Compute a number of `unshift' slots --- * |
77 | * |
78 | * When returning from this function, the offset will be set to @slots@. |
79 | * If @unshift@ is zero, there's no point in reserving slots. Otherwise |
80 | * choose a power of two greater than @unshift@, with a minimum of |
81 | * @DA_SLOTS@. Then add the number of slots to the requirement. |
82 | */ |
83 | |
84 | if (!b->unshift) |
85 | slots = 0; |
86 | else { |
87 | slots = DA_SLOTS; |
88 | while (slots < b->unshift) |
89 | slots <<= 1; |
90 | } |
91 | rq += slots; |
92 | |
93 | /* --- Maybe just shunt data around a bit --- * |
94 | * |
95 | * If the vector is large enough, then theoretically we could cope by |
c6e5bbae |
96 | * moving the objects about in their existing storage. It's not worth |
97 | * bothering if there's not actually double the amount of space I need. |
3745e24b |
98 | */ |
99 | |
c6e5bbae |
100 | if (rq * 2 < b->sz + b->off) { |
3745e24b |
101 | q = p - (b->off - slots) * sz; |
102 | memmove(q, p, b->len * sz); |
103 | b->sz += b->off - slots; |
104 | b->off = slots; |
105 | b->unshift = b->push = 0; |
106 | return (q); |
107 | } |
108 | |
c6e5bbae |
109 | /* --- Decide on a new size --- * |
85bb21f7 |
110 | * |
c6e5bbae |
111 | * There's a minimum possible size for the array which is used if it's |
112 | * currently completely empty. Otherwise I choose the smallest power of |
113 | * two which is big enough, starting at double the current size. |
85bb21f7 |
114 | */ |
3745e24b |
115 | |
f8509853 |
116 | nsz = v ? b->sz + b->off : (DA_INITSZ >> 1); |
3745e24b |
117 | do nsz <<= 1; while (nsz < rq); |
c6e5bbae |
118 | |
119 | /* --- Reallocate the block --- * |
120 | * |
121 | * If I'm not changing the base offset then it's worth using @realloc@; |
122 | * otherwise there'll probably be two calls to @memcpy@ to shunt the data |
123 | * around so it's not worth bothering. |
124 | */ |
125 | |
85bb21f7 |
126 | if (p && slots == b->off) { |
b5ea4de3 |
127 | q = x_realloc(b->a, p - b->off * sz, nsz * sz, b->sz + b->off); |
85bb21f7 |
128 | q += slots * sz; |
129 | } else { |
20eb516f |
130 | q = x_alloc(b->a, nsz * sz); |
85bb21f7 |
131 | q += slots * sz; |
132 | if (p) { |
133 | memcpy(q, p, b->len * sz); |
20eb516f |
134 | x_free(b->a, p - b->off * sz); |
85bb21f7 |
135 | } |
136 | } |
c6e5bbae |
137 | |
138 | /* --- Fill in the other parts of the base structure --- */ |
139 | |
3745e24b |
140 | b->off = slots; |
141 | b->sz = nsz - slots; |
142 | b->unshift = b->push = 0; |
143 | return (q); |
144 | } |
145 | |
146 | /* --- @da_shunt@ --- * |
147 | * |
148 | * Arguments: @da_base *b@ = pointer to array base structure |
149 | * @void *v@ = pointer to array vector |
150 | * @size_t sz@ = size of the array elements |
151 | * @size_t n@ = number of items required at the start |
152 | * |
153 | * Returns: Pointer to appropriately bodged vector. |
154 | * |
155 | * Use: Extends an array to accommodate items inserted at its front. |
156 | * This function is a helper for the @DA_SHUNT@ macro, which |
157 | * should be used by preference. |
158 | */ |
159 | |
160 | void *da_shunt(da_base *b, void *v, size_t sz, size_t n) |
161 | { |
162 | size_t rq; |
163 | char *p = v, *q; |
164 | size_t nsz; |
165 | size_t slots; |
166 | |
167 | /* --- Make sure there's something which needs doing --- * |
168 | * |
169 | * If there's enough space already then return immediately. |
170 | */ |
171 | |
172 | if (n < b->off) |
173 | return (p); |
174 | |
175 | /* --- Compute a number of `push' slots --- * |
176 | * |
177 | * When returning from this function, there will be @slots@ free spaces at |
178 | * the end of the array. If @push@ is zero, there's no point in reserving |
179 | * slots. Otherwise choose a power of two greater than @push@, with a |
180 | * minimum of @DA_SLOTS@. To simplify matters, add the number of items |
181 | * already in the array to @slots@, and then add the number of slots to the |
182 | * requirement. |
183 | */ |
184 | |
185 | if (!b->push) |
186 | slots = 0; |
187 | else { |
188 | slots = DA_SLOTS; |
189 | while (slots < b->push) |
190 | slots <<= 1; |
191 | } |
192 | slots += b->len; |
193 | rq = n + slots; |
194 | |
195 | /* --- Maybe just shunt data around a bit --- * |
196 | * |
197 | * If the vector is large enough, then theoretically we could cope by |
c6e5bbae |
198 | * moving the objects about in their existing storage. Again, if there's |
199 | * not actually twice the space needed, reallocate the array. |
3745e24b |
200 | */ |
201 | |
c6e5bbae |
202 | if (rq * 2 < b->sz + b->off) { |
3745e24b |
203 | q = p + (b->sz - slots) * sz; |
204 | memmove(q, p, b->len * sz); |
205 | b->off += b->sz - slots; |
206 | b->sz = slots; |
207 | b->unshift = b->push = 0; |
208 | return (q); |
209 | } |
210 | |
85bb21f7 |
211 | /* --- Reallocate the array --- * |
212 | * |
213 | * The neat @realloc@ code doesn't need to be here: the offset changes |
214 | * almost all the time -- that's the whole point of this routine! |
215 | */ |
3745e24b |
216 | |
c6e5bbae |
217 | /* --- Decide on a new size --- * |
218 | * |
219 | * There's a minimum possible size for the array which is used if it's |
220 | * currently completely empty. Otherwise I choose the smallest power of |
221 | * two which is big enough, starting at double the current size. |
222 | */ |
223 | |
f8509853 |
224 | nsz = v ? b->sz + b->off : (DA_INITSZ >> 1); |
3745e24b |
225 | do nsz <<= 1; while (nsz < rq); |
c6e5bbae |
226 | |
227 | /* --- Reallocate the block --- * |
228 | * |
229 | * The neat @realloc@ code doesn't need to be here: the offset changes |
230 | * almost all the time -- that's the whole point of this routine! |
231 | */ |
232 | |
20eb516f |
233 | q = x_alloc(b->a, nsz * sz); |
3745e24b |
234 | q += (nsz - slots) * sz; |
85bb21f7 |
235 | if (p) { |
236 | memcpy(q, p, b->len * sz); |
20eb516f |
237 | x_free(b->a, p - b->off * sz); |
85bb21f7 |
238 | } |
c6e5bbae |
239 | |
240 | /* --- Fill in the other parts of the base structure --- */ |
241 | |
3745e24b |
242 | b->off = nsz - slots; |
243 | b->sz = slots; |
244 | b->unshift = b->push = 0; |
245 | return (q); |
246 | } |
247 | |
248 | /* --- @da_tidy@ --- * |
249 | * |
250 | * Arguments: @da_base *b@ = pointer to array base structure |
251 | * @void *v@ = pointer to vector |
252 | * @size_t sz@ = size of the array elements |
253 | * |
254 | * Returns: Newly allocated vector. |
255 | * |
256 | * Use: Minimizes the space occupied by an array. This function is a |
257 | * helper for the @DA_TIDY@ macro, which should be used by |
258 | * preference. |
259 | */ |
260 | |
261 | void *da_tidy(da_base *b, void *v, size_t sz) |
262 | { |
263 | char *p = v, *q; |
264 | |
265 | b->unshift = b->push = 0; |
266 | |
267 | if (!p) |
268 | return (0); |
269 | if (b->sz == b->len && b->off == 0) |
270 | return (p); |
271 | |
272 | if (!b->len) { |
20eb516f |
273 | xfree(p - b->off * sz); |
3745e24b |
274 | return (0); |
275 | } |
276 | |
20eb516f |
277 | q = x_alloc(b->a, b->len * sz); |
3745e24b |
278 | memcpy(q, p, b->len * sz); |
20eb516f |
279 | x_free(b->a, p - b->off * sz); |
3745e24b |
280 | b->sz = b->len; |
281 | b->off = 0; |
282 | return (q); |
283 | } |
284 | |
285 | /* --- Note about testing --- * |
286 | * |
287 | * The test rig for this code is split into three parts. There's `da-gtest', |
288 | * which is a Perl script which generates a list of commands. The `da-ref' |
289 | * Perl script interprets these commands as operations on a Perl array. It's |
290 | * relatively conservatively written and believed to be reliable. The |
291 | * `da-test.c' file implements a command reader for the same syntax and |
292 | * performs the operations on an integer darray, producing output in the same |
293 | * format. To test darray, generate a command script with `da-gtest', pass |
294 | * it through both `da-ref' and `da-test' (the result of compiling |
295 | * da-test.c'), and compare the results. If they're not byte-for-byte |
296 | * identical, there's something wrong. |
297 | */ |
298 | |
299 | /*----- That's all, folks -------------------------------------------------*/ |