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1 | /* -*-c-*- |
2 | * |
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3 | * $Id: mparena.c,v 1.2 1999/11/21 22:14:19 mdw Exp $ |
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4 | * |
5 | * Allocation and freeing of MP buffers |
6 | * |
7 | * (c) 1999 Straylight/Edgeware |
8 | */ |
9 | |
10 | /*----- Licensing notice --------------------------------------------------* |
11 | * |
12 | * This file is part of Catacomb. |
13 | * |
14 | * Catacomb 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 | * Catacomb 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 Catacomb; 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: mparena.c,v $ |
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33 | * Revision 1.2 1999/11/21 22:14:19 mdw |
34 | * Fix bug. Improve diagnostic capabilities. |
35 | * |
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36 | * Revision 1.1 1999/11/17 18:02:16 mdw |
37 | * New multiprecision integer arithmetic suite. |
38 | * |
39 | */ |
40 | |
41 | /*----- Header files ------------------------------------------------------*/ |
42 | |
43 | #include <stdio.h> |
44 | #include <stdlib.h> |
45 | #include <string.h> |
46 | |
47 | #include <mLib/alloc.h> |
48 | #include <mLib/sub.h> |
49 | |
50 | #include "mparena.h" |
51 | |
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52 | /*----- Tweakables --------------------------------------------------------*/ |
53 | |
54 | /* #define MPARENA_TRIVIAL */ |
55 | |
56 | /* #define MPARENA_DEBUG "mparena.out" */ |
57 | |
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58 | /*----- Default allocator -------------------------------------------------*/ |
59 | |
60 | static void *defalloc(mparena *a, size_t sz) { return xmalloc(sz); } |
61 | static void deffree(mparena *a, void *p) { free(p); } |
62 | |
63 | mparena_ops mparena_defops = { defalloc, deffree }; |
64 | |
65 | /*----- Static variables --------------------------------------------------*/ |
66 | |
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67 | #ifdef MPARENA_DEBUG |
68 | static FILE *debugfp = 0; |
69 | |
70 | # define MPARENA_OPENFILE do { \ |
71 | if (!debugfp) { \ |
72 | if ((debugfp = fopen(MPARENA_DEBUG, "w")) == 0) { \ |
73 | fprintf(stderr, "couldn't open debug output file\n"); \ |
74 | exit(EXIT_FAILURE); \ |
75 | } \ |
76 | } \ |
77 | } while (0) |
78 | |
79 | #endif |
80 | |
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81 | static mparena arena = { 0, &mparena_defops }; |
82 | |
83 | #define MPARENA_RESOLVE(a) do { \ |
84 | if ((a) == MPARENA_GLOBAL) \ |
85 | (a) = &arena; \ |
86 | } while (0) |
87 | |
88 | /*----- Main code ---------------------------------------------------------*/ |
89 | |
90 | /* --- @tdump@ --- * |
91 | * |
92 | * Arguments: @mparena_node *n@ = pointer to tree node to dump |
93 | * |
94 | * Returns: --- |
95 | * |
96 | * Use: Recursively dumps out the allocation tree. |
97 | */ |
98 | |
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99 | #ifdef MPARENA_DEBUG |
100 | |
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101 | static void tdump(mparena_node *n) |
102 | { |
103 | if (!n) |
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104 | putc('*', debugfp); |
d3409d5e |
105 | else { |
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106 | putc('(', debugfp); |
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107 | tdump(n->left); |
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108 | fprintf(debugfp, ", %u, ", n->v[0]); |
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109 | tdump(n->right); |
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110 | putc(')', debugfp); |
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111 | } |
112 | } |
113 | |
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114 | #endif |
115 | |
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116 | /* --- @mparena_create@ --- * |
117 | * |
118 | * Arguments: @mparena *a@ = pointer to arena block |
119 | * |
120 | * Returns: --- |
121 | * |
122 | * Use: Initializes an MP arena so that blocks can be allocated from |
123 | * it. |
124 | */ |
125 | |
126 | void mparena_create(mparena *a) |
127 | { |
128 | a->root = 0; |
129 | a->ops = &mparena_defops; |
130 | } |
131 | |
132 | /* --- @mparena_setops@ --- * |
133 | * |
134 | * Arguments: @mparena *a@ = pointer to arena block |
135 | * @mparena_ops *ops@ = pointer to operations block or null |
136 | * |
137 | * Returns: The previous operations block. |
138 | * |
139 | * Use: Sets or queries the operations attached to an arena. |
140 | */ |
141 | |
142 | mparena_ops *mparena_setops(mparena *a, mparena_ops *ops) |
143 | { |
144 | mparena_ops *o; |
145 | MPARENA_RESOLVE(a); |
146 | o = a->ops; |
147 | if (ops) |
148 | a->ops = ops; |
149 | return (0); |
150 | } |
151 | |
152 | /* --- @mparena_destroy@ --- * |
153 | * |
154 | * Arguments: @mparena *a@ = pointer to arena block |
155 | * |
156 | * Returns: --- |
157 | * |
158 | * Use: Frees an MP arena, and all the vectors held within it. The |
159 | * blocks which are currently allocated can be freed into some |
160 | * other arena. |
161 | */ |
162 | |
163 | static void tfree(mparena *a, mparena_node *n) |
164 | { |
165 | a->ops->free(a, n->v); |
166 | if (n->left) |
167 | tfree(a, n->left); |
168 | if (n->right) |
169 | tfree(a, n->right); |
170 | DESTROY(n); |
171 | } |
172 | |
173 | void mparena_destroy(mparena *a) |
174 | { |
175 | tfree(a, a->root); |
176 | a->root = 0; |
177 | } |
178 | |
179 | /* --- @mpalloc@ --- * |
180 | * |
181 | * Arguments: @mparena *a@ = pointer to arena block |
182 | * @size_t sz@ = number of digits required |
183 | * |
184 | * Returns: Pointer to a suitably sized block. |
185 | * |
186 | * Use: Allocates a lump of data suitable for use as an array of MP |
187 | * digits. |
188 | */ |
189 | |
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190 | #ifdef MPARENA_TRIVIAL |
191 | |
192 | mpw *mpalloc(mparena *a, size_t sz) |
193 | { |
194 | MPARENA_RESOLVE(a); |
195 | return (a->ops->alloc(a, MPWS(sz))); |
196 | } |
197 | |
198 | #else |
199 | |
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200 | mpw *mpalloc(mparena *a, size_t sz) |
201 | { |
202 | mparena_node **nn, *n; |
203 | mpw *v; |
204 | |
205 | MPARENA_RESOLVE(a); |
206 | nn = &a->root; |
207 | |
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208 | #ifdef MPARENA_DEBUG |
209 | MPARENA_OPENFILE; |
210 | fprintf(debugfp, "alloc %u\n before: ", sz); |
211 | tdump(a->root); putc('\n', debugfp); |
212 | if (sz == 0) |
213 | asm("nop"); |
d3409d5e |
214 | #endif |
215 | |
216 | /* --- First, find a block which is big enough --- */ |
217 | |
218 | again: |
219 | n = *nn; |
220 | if (!n) { |
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221 | #ifdef MPARENA_DEBUG |
222 | fputs(" failed\n", debugfp); |
223 | #endif |
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224 | v = a->ops->alloc(a, MPWS(sz + 1)); |
225 | v[0] = sz; |
226 | return (v + 1); |
227 | } |
228 | if (n->v[0] < sz) { |
229 | nn = &n->right; |
230 | goto again; |
231 | } |
232 | |
233 | /* --- Now try to find a smaller block which is suitable --- */ |
234 | |
235 | while (n->left && n->left->v[0] >= sz) { |
236 | nn = &n->left; |
237 | n = *nn; |
238 | } |
239 | |
240 | /* --- If the block we've got is still too large, start digging --- */ |
241 | |
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242 | if (n->v[0] > sz * 2) { |
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243 | nn = &n->left; |
244 | goto again; |
245 | } |
246 | |
247 | /* --- I've now found a suitable block --- */ |
248 | |
249 | v = n->v; |
250 | |
251 | /* --- Remove this node from the tree --- */ |
252 | |
253 | if (!n->left) |
254 | *nn = n->right; |
255 | else if (!n->right) |
256 | *nn = n->left; |
257 | else { |
258 | mparena_node *left = n->left; |
259 | mparena_node *p = *nn = n->right; |
260 | while (p->left) |
261 | p = p->left; |
262 | p->left = left; |
263 | } |
264 | |
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265 | #ifdef MPARENA_DEBUG |
266 | fputs(" after: ", debugfp); |
267 | tdump(a->root); putc('\n', debugfp); |
268 | #endif |
269 | |
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270 | /* --- Get rid of this node now --- */ |
271 | |
272 | DESTROY(n); |
273 | return (v + 1); |
274 | } |
275 | |
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276 | #endif |
277 | |
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278 | /* --- @mpfree@ --- * |
279 | * |
280 | * Arguments: @mparena *a@ = pointer to arena block |
281 | * @mpw *v@ = pointer to allocated vector |
282 | * |
283 | * Returns: --- |
284 | * |
285 | * Use: Returns an MP vector to an arena. It doesn't have to be |
286 | * returned to the arena from which it was allocated. |
287 | */ |
288 | |
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289 | #ifdef MPARENA_TRIVIAL |
290 | |
291 | void mpfree(mparena *a, mpw *v) |
292 | { |
293 | MPARENA_RESOLVE(a); |
294 | a->ops->free(a, v); |
295 | } |
296 | |
297 | #else |
298 | |
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299 | void mpfree(mparena *a, mpw *v) |
300 | { |
301 | mparena_node **nn, *n; |
302 | size_t sz = *--v; |
303 | |
304 | MPARENA_RESOLVE(a); |
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305 | |
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306 | #ifdef MPARENA_DEBUG |
307 | MPARENA_OPENFILE; |
308 | fprintf(debugfp, "free %u\n before: ", sz); |
309 | tdump(a->root); putc('\n', debugfp); |
310 | #endif |
311 | |
312 | nn = &a->root; |
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313 | while (*nn) { |
314 | n = *nn; |
315 | if (n->v[0] > sz) |
316 | nn = &n->left; |
317 | else |
318 | nn = &n->right; |
319 | } |
320 | |
321 | n = CREATE(mparena_node); |
322 | n->left = n->right = 0; |
323 | n->v = v; |
324 | *nn = n; |
325 | |
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326 | #ifdef MPARENA_DEBUG |
327 | fputs(" after: ", debugfp); |
328 | tdump(a->root); putc('\n', debugfp); |
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329 | #endif |
330 | } |
331 | |
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332 | #endif |
333 | |
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334 | /*----- That's all, folks -------------------------------------------------*/ |