3745e24b |
1 | /* -*-c-*- |
2 | * |
85bb21f7 |
3 | * $Id: darray.c,v 1.3 1999/10/29 22:59:22 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 | |
30 | /*----- Revision history --------------------------------------------------* |
31 | * |
32 | * $Log: darray.c,v $ |
85bb21f7 |
33 | * Revision 1.3 1999/10/29 22:59:22 mdw |
34 | * New array adjustment macros for unsigned arguments. |
35 | * |
f8509853 |
36 | * Revision 1.2 1999/10/28 22:05:28 mdw |
37 | * Modify and debug allocation routines. |
38 | * |
3745e24b |
39 | * Revision 1.1 1999/10/22 22:37:26 mdw |
40 | * New dynamic array implementation replaces `dynarray.h'. |
41 | * |
42 | */ |
43 | |
44 | /*----- Header files ------------------------------------------------------*/ |
45 | |
46 | #include <stdio.h> |
47 | #include <string.h> |
48 | #include <stdlib.h> |
49 | |
50 | #include "alloc.h" |
51 | #include "darray.h" |
52 | |
53 | /*----- Magic numbers -----------------------------------------------------*/ |
54 | |
f8509853 |
55 | #define DA_INITSZ 16 /* Default size for new array */ |
3745e24b |
56 | #define DA_SLOTS 8 /* Number of preshifted slots */ |
57 | |
58 | /*----- Main code ---------------------------------------------------------*/ |
59 | |
60 | /* --- @da_ensure@ --- * |
61 | * |
62 | * Arguments: @da_base *b@ = pointer to array base structure |
63 | * @void *v@ = pointer to array vector |
64 | * @size_t sz@ = size of individual array elements |
65 | * @size_t n@ = number of items required at the end |
66 | * |
67 | * Returns: Pointer to newly allocated or adjusted array vector. |
68 | * |
69 | * Use: Extends a dynamic array to accommodate a number of new items |
70 | * at its end. This function is a helper for the @DA_ENSURE@ |
71 | * macro, which should be used by preference. |
72 | */ |
73 | |
74 | void *da_ensure(da_base *b, void *v, size_t sz, size_t n) |
75 | { |
76 | size_t rq = n + b->len; |
77 | char *p = v, *q; |
78 | size_t nsz; |
79 | size_t slots; |
80 | |
81 | /* --- Make sure there's something which needs doing --- * |
82 | * |
83 | * If there's enough space already then return immediately. |
84 | */ |
85 | |
86 | if (rq < b->sz) |
87 | return (p); |
88 | |
89 | /* --- Compute a number of `unshift' slots --- * |
90 | * |
91 | * When returning from this function, the offset will be set to @slots@. |
92 | * If @unshift@ is zero, there's no point in reserving slots. Otherwise |
93 | * choose a power of two greater than @unshift@, with a minimum of |
94 | * @DA_SLOTS@. Then add the number of slots to the requirement. |
95 | */ |
96 | |
97 | if (!b->unshift) |
98 | slots = 0; |
99 | else { |
100 | slots = DA_SLOTS; |
101 | while (slots < b->unshift) |
102 | slots <<= 1; |
103 | } |
104 | rq += slots; |
105 | |
106 | /* --- Maybe just shunt data around a bit --- * |
107 | * |
108 | * If the vector is large enough, then theoretically we could cope by |
109 | * moving the objects about in their existing storage. |
110 | */ |
111 | |
112 | if (rq < b->sz + b->off) { |
113 | q = p - (b->off - slots) * sz; |
114 | memmove(q, p, b->len * sz); |
115 | b->sz += b->off - slots; |
116 | b->off = slots; |
117 | b->unshift = b->push = 0; |
118 | return (q); |
119 | } |
120 | |
85bb21f7 |
121 | /* --- Reallocate the array --- * |
122 | * |
123 | * If the offset isn't changing, it's sensible to use @realloc@ if |
124 | * available. Otherwise the overhead of copying all the data twice |
125 | * probably isn't worth it. |
126 | */ |
3745e24b |
127 | |
f8509853 |
128 | nsz = v ? b->sz + b->off : (DA_INITSZ >> 1); |
3745e24b |
129 | do nsz <<= 1; while (nsz < rq); |
85bb21f7 |
130 | if (p && slots == b->off) { |
131 | q = xrealloc(p - b->off * sz, nsz * sz); |
132 | q += slots * sz; |
133 | } else { |
134 | q = xmalloc(nsz * sz); |
135 | q += slots * sz; |
136 | if (p) { |
137 | memcpy(q, p, b->len * sz); |
138 | free(p - b->off * sz); |
139 | } |
140 | } |
3745e24b |
141 | b->off = slots; |
142 | b->sz = nsz - slots; |
143 | b->unshift = b->push = 0; |
144 | return (q); |
145 | } |
146 | |
147 | /* --- @da_shunt@ --- * |
148 | * |
149 | * Arguments: @da_base *b@ = pointer to array base structure |
150 | * @void *v@ = pointer to array vector |
151 | * @size_t sz@ = size of the array elements |
152 | * @size_t n@ = number of items required at the start |
153 | * |
154 | * Returns: Pointer to appropriately bodged vector. |
155 | * |
156 | * Use: Extends an array to accommodate items inserted at its front. |
157 | * This function is a helper for the @DA_SHUNT@ macro, which |
158 | * should be used by preference. |
159 | */ |
160 | |
161 | void *da_shunt(da_base *b, void *v, size_t sz, size_t n) |
162 | { |
163 | size_t rq; |
164 | char *p = v, *q; |
165 | size_t nsz; |
166 | size_t slots; |
167 | |
168 | /* --- Make sure there's something which needs doing --- * |
169 | * |
170 | * If there's enough space already then return immediately. |
171 | */ |
172 | |
173 | if (n < b->off) |
174 | return (p); |
175 | |
176 | /* --- Compute a number of `push' slots --- * |
177 | * |
178 | * When returning from this function, there will be @slots@ free spaces at |
179 | * the end of the array. If @push@ is zero, there's no point in reserving |
180 | * slots. Otherwise choose a power of two greater than @push@, with a |
181 | * minimum of @DA_SLOTS@. To simplify matters, add the number of items |
182 | * already in the array to @slots@, and then add the number of slots to the |
183 | * requirement. |
184 | */ |
185 | |
186 | if (!b->push) |
187 | slots = 0; |
188 | else { |
189 | slots = DA_SLOTS; |
190 | while (slots < b->push) |
191 | slots <<= 1; |
192 | } |
193 | slots += b->len; |
194 | rq = n + slots; |
195 | |
196 | /* --- Maybe just shunt data around a bit --- * |
197 | * |
198 | * If the vector is large enough, then theoretically we could cope by |
199 | * moving the objects about in their existing storage. |
200 | */ |
201 | |
202 | if (rq < b->sz + b->off) { |
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 | |
f8509853 |
217 | nsz = v ? b->sz + b->off : (DA_INITSZ >> 1); |
3745e24b |
218 | do nsz <<= 1; while (nsz < rq); |
219 | q = xmalloc(nsz * sz); |
220 | q += (nsz - slots) * sz; |
85bb21f7 |
221 | if (p) { |
222 | memcpy(q, p, b->len * sz); |
3745e24b |
223 | free(p - b->off * sz); |
85bb21f7 |
224 | } |
3745e24b |
225 | b->off = nsz - slots; |
226 | b->sz = slots; |
227 | b->unshift = b->push = 0; |
228 | return (q); |
229 | } |
230 | |
231 | /* --- @da_tidy@ --- * |
232 | * |
233 | * Arguments: @da_base *b@ = pointer to array base structure |
234 | * @void *v@ = pointer to vector |
235 | * @size_t sz@ = size of the array elements |
236 | * |
237 | * Returns: Newly allocated vector. |
238 | * |
239 | * Use: Minimizes the space occupied by an array. This function is a |
240 | * helper for the @DA_TIDY@ macro, which should be used by |
241 | * preference. |
242 | */ |
243 | |
244 | void *da_tidy(da_base *b, void *v, size_t sz) |
245 | { |
246 | char *p = v, *q; |
247 | |
248 | b->unshift = b->push = 0; |
249 | |
250 | if (!p) |
251 | return (0); |
252 | if (b->sz == b->len && b->off == 0) |
253 | return (p); |
254 | |
255 | if (!b->len) { |
256 | free(p - b->off * sz); |
257 | return (0); |
258 | } |
259 | |
260 | q = xmalloc(b->len * sz); |
261 | memcpy(q, p, b->len * sz); |
262 | free(p - b->off * sz); |
263 | b->sz = b->len; |
264 | b->off = 0; |
265 | return (q); |
266 | } |
267 | |
268 | /* --- Note about testing --- * |
269 | * |
270 | * The test rig for this code is split into three parts. There's `da-gtest', |
271 | * which is a Perl script which generates a list of commands. The `da-ref' |
272 | * Perl script interprets these commands as operations on a Perl array. It's |
273 | * relatively conservatively written and believed to be reliable. The |
274 | * `da-test.c' file implements a command reader for the same syntax and |
275 | * performs the operations on an integer darray, producing output in the same |
276 | * format. To test darray, generate a command script with `da-gtest', pass |
277 | * it through both `da-ref' and `da-test' (the result of compiling |
278 | * da-test.c'), and compare the results. If they're not byte-for-byte |
279 | * identical, there's something wrong. |
280 | */ |
281 | |
282 | /*----- That's all, folks -------------------------------------------------*/ |