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comparison src/dynarr.c @ 428:3ecd8885ac67 r21-2-22

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date Mon, 13 Aug 2007 11:28:15 +0200
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1 /* Simple 'n' stupid dynamic-array module.
2 Copyright (C) 1993 Sun Microsystems, Inc.
3
4 This file is part of XEmacs.
5
6 XEmacs is free software; you can redistribute it and/or modify it
7 under the terms of the GNU General Public License as published by the
8 Free Software Foundation; either version 2, or (at your option) any
9 later version.
10
11 XEmacs is distributed in the hope that it will be useful, but WITHOUT
12 ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
13 FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
14 for more details.
15
16 You should have received a copy of the GNU General Public License
17 along with XEmacs; see the file COPYING. If not, write to
18 the Free Software Foundation, Inc., 59 Temple Place - Suite 330,
19 Boston, MA 02111-1307, USA. */
20
21 /* Synched up with: Not in FSF. */
22
23 /* Written by Ben Wing, December 1993. */
24
25 /*
26
27 A "dynamic array" is a contiguous array of fixed-size elements where there
28 is no upper limit (except available memory) on the number of elements in the
29 array. Because the elements are maintained contiguously, space is used
30 efficiently (no per-element pointers necessary) and random access to a
31 particular element is in constant time. At any one point, the block of memory
32 that holds the array has an upper limit; if this limit is exceeded, the
33 memory is realloc()ed into a new array that is twice as big. Assuming that
34 the time to grow the array is on the order of the new size of the array
35 block, this scheme has a provably constant amortized time (i.e. average
36 time over all additions).
37
38 When you add elements or retrieve elements, pointers are used. Note that
39 the element itself (of whatever size it is), and not the pointer to it,
40 is stored in the array; thus you do not have to allocate any heap memory
41 on your own. Also, returned pointers are only guaranteed to be valid
42 until the next operation that changes the length of the array.
43
44 This is a container object. Declare a dynamic array of a specific type
45 as follows:
46
47 typedef struct
48 {
49 Dynarr_declare (mytype);
50 } mytype_dynarr;
51
52 Use the following functions/macros:
53
54 void *Dynarr_new(type)
55 [MACRO] Create a new dynamic-array object, with each element of the
56 specified type. The return value is cast to (type##_dynarr).
57 This requires following the convention that types are declared in
58 such a way that this type concatenation works. In particular, TYPE
59 must be a symbol, not an arbitrary C type.
60
61 Dynarr_add(d, el)
62 [MACRO] Add an element to the end of a dynamic array. EL is a pointer
63 to the element; the element itself is stored in the array, however.
64 No function call is performed unless the array needs to be resized.
65
66 Dynarr_add_many(d, base, len)
67 [MACRO] Add LEN elements to the end of the dynamic array. The elements
68 should be contiguous in memory, starting at BASE.
69
70 Dynarr_insert_many_at_start(d, base, len)
71 [MACRO] Append LEN elements to the beginning of the dynamic array.
72 The elements should be contiguous in memory, starting at BASE.
73
74 Dynarr_insert_many(d, base, len, start)
75 Insert LEN elements to the dynamic array starting at position
76 START. The elements should be contiguous in memory, starting at BASE.
77
78 int Dynarr_length(d)
79 [MACRO] Return the number of elements currently in a dynamic array.
80
81 int Dynarr_largest(d)
82 [MACRO] Return the maximum value that Dynarr_length(d) would
83 ever have returned.
84
85 type Dynarr_at(d, i)
86 [MACRO] Return the element at the specified index (no bounds checking
87 done on the index). The element itself is returned, not a pointer
88 to it.
89
90 type *Dynarr_atp(d, i)
91 [MACRO] Return a pointer to the element at the specified index (no
92 bounds checking done on the index). The pointer may not be valid
93 after an element is added to or removed from the array.
94
95 Dynarr_reset(d)
96 [MACRO] Reset the length of a dynamic array to 0.
97
98 Dynarr_free(d)
99 Destroy a dynamic array and the memory allocated to it.
100
101 Use the following global variable:
102
103 Dynarr_min_size
104 Minimum allowable size for a dynamic array when it is resized. The
105 default is 32 and does not normally need to be changed.
106
107 */
108
109 #include <config.h>
110 #include "lisp.h"
111
112 int Dynarr_min_size = 1;
113
114 static void
115 Dynarr_realloc (Dynarr *dy, int new_size)
116 {
117 if (DUMPEDP (dy->base))
118 {
119 void *new_base = malloc (new_size);
120 memcpy (new_base, dy->base, dy->max > new_size ? new_size : dy->max);
121 dy->base = new_base;
122 }
123 else
124 dy->base = xrealloc (dy->base, new_size);
125 }
126
127 void *
128 Dynarr_newf (int elsize)
129 {
130 Dynarr *d = xnew_and_zero (Dynarr);
131 d->elsize = elsize;
132
133 return d;
134 }
135
136 void
137 Dynarr_resize (void *d, int size)
138 {
139 int newsize;
140 double multiplier;
141 Dynarr *dy = (Dynarr *) d;
142
143 if (dy->max <= 8)
144 multiplier = 2;
145 else
146 multiplier = 1.5;
147
148 for (newsize = dy->max; newsize < size;)
149 newsize = max (Dynarr_min_size, (int) (multiplier * newsize));
150
151 /* Don't do anything if the array is already big enough. */
152 if (newsize > dy->max)
153 {
154 Dynarr_realloc (dy, newsize*dy->elsize);
155 dy->max = newsize;
156 }
157 }
158
159 /* Add a number of contiguous elements to the array starting at START. */
160 void
161 Dynarr_insert_many (void *d, CONST void *el, int len, int start)
162 {
163 Dynarr *dy = (Dynarr *) d;
164
165 Dynarr_resize (dy, dy->cur+len);
166 /* Silently adjust start to be valid. */
167 if (start > dy->cur)
168 start = dy->cur;
169 else if (start < 0)
170 start = 0;
171
172 if (start != dy->cur)
173 {
174 memmove ((char *) dy->base + (start + len)*dy->elsize,
175 (char *) dy->base + start*dy->elsize,
176 (dy->cur - start)*dy->elsize);
177 }
178 memcpy ((char *) dy->base + start*dy->elsize, el, len*dy->elsize);
179 dy->cur += len;
180
181 if (dy->cur > dy->largest)
182 dy->largest = dy->cur;
183 }
184
185 void
186 Dynarr_delete_many (void *d, int start, int len)
187 {
188 Dynarr *dy = (Dynarr *) d;
189
190 assert (start >= 0 && len >= 0 && start + len <= dy->cur);
191 memmove ((char *) dy->base + start*dy->elsize,
192 (char *) dy->base + (start + len)*dy->elsize,
193 (dy->cur - start - len)*dy->elsize);
194 dy->cur -= len;
195 }
196
197 void
198 Dynarr_free (void *d)
199 {
200 Dynarr *dy = (Dynarr *) d;
201
202 if (dy->base && !DUMPEDP (dy->base))
203 xfree (dy->base);
204 if(!DUMPEDP (dy))
205 xfree (dy);
206 }
207
208 #ifdef MEMORY_USAGE_STATS
209
210 /* Return memory usage for Dynarr D. The returned value is the total
211 amount of bytes actually being used for the Dynarr, including all
212 overhead. The extra amount of space in the Dynarr that is
213 allocated beyond what was requested is returned in DYNARR_OVERHEAD
214 in STATS. The extra amount of space that malloc() allocates beyond
215 what was requested of it is returned in MALLOC_OVERHEAD in STATS.
216 See the comment above the definition of this structure. */
217
218 size_t
219 Dynarr_memory_usage (void *d, struct overhead_stats *stats)
220 {
221 size_t total = 0;
222 Dynarr *dy = (Dynarr *) d;
223
224 /* We have to be a bit tricky here because not all of the
225 memory that malloc() will claim as "requested" was actually
226 requested. */
227
228 if (dy->base)
229 {
230 size_t malloc_used = malloced_storage_size (dy->base,
231 dy->elsize * dy->max, 0);
232 /* #### This may or may not be correct. Some Dynarrs would
233 prefer that we use dy->cur instead of dy->largest here. */
234 int was_requested = dy->elsize * dy->largest;
235 int dynarr_overhead = dy->elsize * (dy->max - dy->largest);
236
237 total += malloc_used;
238 stats->was_requested += was_requested;
239 stats->dynarr_overhead += dynarr_overhead;
240 /* And the remainder must be malloc overhead. */
241 stats->malloc_overhead +=
242 malloc_used - was_requested - dynarr_overhead;
243 }
244
245 total += malloced_storage_size (d, sizeof (*dy), stats);
246
247 return total;
248 }
249
250 #endif /* MEMORY_USAGE_STATS */