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1 | /* -*-c-*- |
2 | * |
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3 | * $Id: mp-mem.c,v 1.6 2004/04/03 03:30:22 mdw Exp $ |
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4 | * |
5 | * Memory management for multiprecision numbers |
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: mp-mem.c,v $ |
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33 | * Revision 1.6 2004/04/03 03:30:22 mdw |
34 | * Fix long-standing stupidity in @mp_dest@. |
35 | * |
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36 | * Revision 1.5 2001/06/16 12:57:00 mdw |
37 | * Implement some missing functions. |
38 | * |
f1140c41 |
39 | * Revision 1.4 2001/02/03 12:00:29 mdw |
40 | * Now @mp_drop@ checks its argument is non-NULL before attempting to free |
41 | * it. Note that the macro version @MP_DROP@ doesn't do this. |
42 | * |
d34decd2 |
43 | * Revision 1.3 2000/06/17 11:45:09 mdw |
44 | * Major memory management overhaul. Added arena support. Use the secure |
45 | * arena for secret integers. Replace and improve the MP management macros |
46 | * (e.g., replace MP_MODIFY by MP_DEST). |
47 | * |
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48 | * Revision 1.2 1999/12/10 23:19:02 mdw |
49 | * Improve error-checking. |
50 | * |
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51 | * Revision 1.1 1999/11/17 18:02:16 mdw |
52 | * New multiprecision integer arithmetic suite. |
53 | * |
54 | */ |
55 | |
56 | /*----- Header files ------------------------------------------------------*/ |
57 | |
d34decd2 |
58 | #include <mLib/sub.h> |
59 | |
60 | |
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61 | #include "mp.h" |
62 | |
63 | /*----- Main code ---------------------------------------------------------*/ |
64 | |
d34decd2 |
65 | /* --- @mp_new@ --- * |
66 | * |
67 | * Arguments: @size_t sz@ = size of vector required |
68 | * @unsigned f@ = flags to set |
69 | * |
70 | * Returns: Pointer to a new MP structure. |
71 | * |
72 | * Use: Allocates a new multiprecision integer. The data space is |
73 | * allocated from either the standard global or secret arena, |
74 | * depending on the initial flags requested. |
75 | */ |
76 | |
77 | mp *mp_new(size_t sz, unsigned f) |
78 | { |
79 | mp *m = CREATE(mp); |
80 | m->a = (f & MP_BURN) ? MPARENA_SECURE : MPARENA_GLOBAL; |
81 | m->v = mpalloc(m->a, sz); |
82 | m->vl = m->v + sz; |
83 | m->sz = sz; |
84 | m->f = f & ~(MP_CONST | MP_DESTROYED); |
85 | m->ref = 1; |
86 | return (m); |
87 | } |
88 | |
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89 | /* --- @mp_create@ --- * |
90 | * |
91 | * Arguments: @size_t sz@ = size of vector required |
92 | * |
93 | * Returns: Pointer to pristine new MP structure with enough memory |
94 | * bolted onto it. |
95 | * |
96 | * Use: Creates a new multiprecision integer, initially zero. The |
97 | * integer has a single reference. |
98 | */ |
99 | |
100 | mp *mp_create(size_t sz) |
101 | { |
102 | mp *m = CREATE(mp); |
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103 | m->v = mpalloc(MPARENA_GLOBAL, sz); |
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104 | m->vl = m->v + sz; |
105 | m->sz = sz; |
d34decd2 |
106 | m->a = MPARENA_GLOBAL; |
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107 | m->f = MP_UNDEF; |
108 | m->ref = 1; |
109 | return (m); |
110 | } |
111 | |
d34decd2 |
112 | /* --- @mp_createsecure@ --- * |
113 | * |
114 | * Arguments: @size_t sz@ = size of vector required |
115 | * |
116 | * Returns: Pointer to pristine new MP structure with enough memory |
117 | * bolted onto it. |
118 | * |
119 | * Use: Creates a new multiprecision integer with indeterminate |
120 | * contents. The integer has a single reference. The integer's |
121 | * data space is allocated from the secure arena. Its burn flag |
122 | * is set. |
123 | */ |
124 | |
125 | mp *mp_createsecure(size_t sz) |
126 | { |
127 | mp *m = CREATE(mp); |
128 | m->v = mpalloc(MPARENA_SECURE, sz); |
129 | m->vl = m->v + sz; |
130 | m->sz = sz; |
131 | m->a = MPARENA_SECURE; |
132 | m->f = MP_UNDEF | MP_BURN; |
133 | m->ref = 1; |
134 | return (m); |
135 | } |
136 | |
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137 | /* --- @mp_build@ --- * |
138 | * |
139 | * Arguments: @mp *m@ = pointer to an MP block to fill in |
140 | * @mpw *v@ = pointer to a word array |
141 | * @mpw *vl@ = pointer just past end of array |
142 | * |
143 | * Returns: --- |
144 | * |
145 | * Use: Creates a multiprecision integer representing some smallish |
146 | * number. You must provide storage for the number and dispose |
147 | * of it when you've finished with it. The number is marked as |
148 | * constant while it exists. |
149 | */ |
150 | |
151 | void mp_build(mp *m, mpw *v, mpw *vl) |
152 | { |
153 | m->v = v; |
154 | m->vl = vl; |
155 | m->sz = vl - v; |
156 | m->f = MP_CONST; |
157 | m->ref = 1; |
158 | } |
159 | |
160 | /* --- @mp_destroy@ --- * |
161 | * |
162 | * Arguments: @mp *m@ = pointer to a multiprecision integer |
163 | * |
164 | * Returns: --- |
165 | * |
166 | * Use: Destroys a multiprecision integer. The reference count isn't |
167 | * checked. Don't use this function if you don't know what |
168 | * you're doing: use @mp_drop@ instead. |
169 | */ |
170 | |
171 | void mp_destroy(mp *m) |
172 | { |
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173 | assert(((void)"Destroying a free integer", !(m->f & MP_DESTROYED))); |
174 | assert(((void)"Attempted to destroy a constant", !(m->f & MP_CONST))); |
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175 | if (m->f & MP_BURN) |
176 | memset(m->v, 0, MPWS(m->sz)); |
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177 | mpfree(m->a, m->v); |
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178 | m->f |= MP_DESTROYED; |
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179 | DESTROY(m); |
180 | } |
181 | |
182 | /* --- @mp_copy@ --- * |
183 | * |
184 | * Arguments: @mp *m@ = pointer to a multiprecision integer |
185 | * |
186 | * Returns: A copy of the given multiprecision integer. |
187 | * |
188 | * Use: Copies the given integer. In fact you just get another |
189 | * reference to the same old one again. |
190 | */ |
191 | |
192 | mp *mp_copy(mp *m) { return MP_COPY(m); } |
193 | |
194 | /* --- @mp_drop@ --- * |
195 | * |
196 | * Arguments: @mp *m@ = pointer to a multiprecision integer |
197 | * |
198 | * Returns: --- |
199 | * |
200 | * Use: Drops a reference to an integer which isn't wanted any more. |
201 | * If there are no more references, the integer is destroyed. |
202 | */ |
203 | |
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204 | void mp_drop(mp *m) { if (m) MP_DROP(m); } |
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205 | |
206 | /* --- @mp_split@ --- * |
207 | * |
208 | * Arguments: @mp *m@ = pointer to a multiprecision integer |
209 | * |
210 | * Returns: A reference to the same integer, possibly with a different |
211 | * address. |
212 | * |
213 | * Use: Splits off a modifiable version of the integer referred to. |
214 | */ |
215 | |
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216 | mp *mp_split(mp *m) { MP_SPLIT(m); return (m); } |
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217 | |
218 | /* --- @mp_resize@ --- * |
219 | * |
220 | * Arguments: @mp *m@ = pointer to a multiprecision integer |
221 | * @size_t sz@ = new size |
222 | * |
223 | * Returns: --- |
224 | * |
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225 | * Use: Changes an integer's size. The length and value are not |
226 | * changed. It is an error to |
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227 | */ |
228 | |
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229 | void mp_resize(mp *m, size_t sz) { MP_RESIZE(m, sz); } |
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230 | |
231 | /* --- @mp_ensure@ --- * |
232 | * |
233 | * Arguments: @mp *m@ = pointer to a multiprecision integer |
d34decd2 |
234 | * @size_t sz@ = required length |
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235 | * |
236 | * Returns: --- |
237 | * |
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238 | * Use: Changes an integer's length. If there is not enough space |
239 | * allocated for the new length then the size is increased. It |
d3409d5e |
240 | */ |
241 | |
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242 | void mp_ensure(mp *m, size_t sz) { MP_ENSURE(m, sz); } |
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243 | |
d34decd2 |
244 | /* --- @mp_dest@ --- * |
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245 | * |
d34decd2 |
246 | * Arguments: @mp *m@ = a suggested destination integer |
247 | * @size_t sz@ = size required for result, in digits |
248 | * @unsigned f@ = various flags |
249 | * |
250 | * Returns: A pointer to an appropriate destination. |
251 | * |
252 | * Use: Converts a suggested destination into a real destination with |
253 | * the required properties. If the real destination is @d@, |
254 | * then the following properties will hold: |
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255 | * |
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256 | * * @d@ will have exactly one reference. |
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257 | * |
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258 | * * If @m@ is not @MP_NEW@, then the contents of @m@ will not |
259 | * change, unless @f@ has the @MP_UNDEF@ flag set. |
260 | * |
261 | * * If @m@ is not @MP_NEW@, then he reference count of @m@ on |
262 | * entry is equal to the sum of the counts of @d@ and @m@ on |
263 | * exit. |
264 | * |
265 | * * The size of @d@ will be at least @sz@. |
266 | * |
267 | * * If @f@ has the @MP_BURN@ flag set, then @d@ will be |
268 | * allocated from @MPARENA_SECURE@. |
269 | * |
270 | * Understanding this function is crucial to using Catacomb's |
271 | * multiprecision integer library effectively. |
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272 | */ |
273 | |
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274 | mp *mp_dest(mp *m, size_t sz, unsigned f) |
275 | { |
276 | /* --- If no destination, make one --- */ |
277 | |
278 | if (m == MP_NEWSEC) |
279 | m = mp_new(sz, f | MP_UNDEF | MP_BURN); |
280 | else if (m == MP_NEW) |
281 | m = mp_new(sz, f | MP_UNDEF); |
282 | else { |
283 | size_t len = MP_LEN(m); |
284 | unsigned undef = (m->f | f) & MP_UNDEF; |
285 | |
286 | /* --- If the value must be preserved, the block can't shrink --- */ |
287 | |
288 | if (!undef && sz < len) |
289 | sz = len; |
290 | |
291 | /* --- Otherwise check whether the destination is suitable --- */ |
292 | |
293 | if (m->ref > 1 || (m->f & MP_CONST) || |
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294 | sz > m->sz || !((f & ~m->f) & MP_BURN)) { |
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295 | |
296 | /* --- No -- allocate a new buffer --- * |
297 | * |
298 | * The buffer must be secure if (a) the caller requested a secure |
299 | * buffer, or (b) the old buffer is secure and I'm not allowed to |
300 | * discard the old contents. |
301 | */ |
302 | |
303 | mparena *a; |
304 | mpw *v; |
305 | |
306 | if ((f & MP_BURN) || (!undef && (m->f & MP_BURN))) |
307 | a = MPARENA_SECURE; |
308 | else |
309 | a = MPARENA_GLOBAL; |
310 | v = mpalloc(a, sz); |
311 | |
312 | /* --- Copy the data over --- */ |
313 | |
314 | if (!undef) { |
315 | memcpy(v, m->v, MPWS(len)); |
316 | if (sz - len > 0) |
317 | memset(v + len, 0, MPWS(sz - len)); |
318 | } |
319 | |
320 | /* --- If @m@ has other references, make a new node --- * |
321 | * |
322 | * Otherwise dispose of the old buffer. |
323 | */ |
324 | |
325 | if (!(m->f & MP_CONST) && m->ref == 1) { |
326 | if (m->f & MP_BURN) |
327 | memset(m->v, 0, MPWS(m->sz)); |
328 | mpfree(m->a, m->v); |
329 | } else { |
330 | mp *mm = CREATE(mp); |
331 | mm->ref = 1; |
332 | mm->f = m->f; |
333 | m->ref--; |
334 | m = mm; |
335 | } |
336 | |
337 | /* --- Fix up the node --- */ |
338 | |
339 | m->v = v; |
340 | m->vl = v + sz; |
341 | m->sz = sz; |
342 | m->f = ((m->f & ~(MP_CONST | MP_BURN)) | |
343 | (f & (MP_BURN | MP_UNDEF))); |
344 | m->a = a; |
345 | } |
346 | |
347 | /* --- If the number is growing in its buffer, fix it up --- */ |
348 | |
349 | else if (sz > len) { |
350 | if (!undef) |
351 | memset(m->vl, 0, MPWS(sz - len)); |
352 | m->vl = m->v + sz; |
353 | } |
354 | } |
355 | |
356 | /* --- Done --- */ |
357 | |
358 | return (m); |
359 | } |
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360 | |
361 | /*----- That's all, folks -------------------------------------------------*/ |