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1 | /* -*-c-*- |
2 | * |
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3 | * $Id: mp-mem.c,v 1.8 2004/04/08 16:17:32 mdw Exp $ |
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4 | * |
5 | * Memory management for multiprecision numbers |
6 | * |
7 | * (c) 1999 Straylight/Edgeware |
8 | */ |
9 | |
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10 | /*----- Licensing notice --------------------------------------------------* |
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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. |
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18 | * |
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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. |
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23 | * |
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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 | |
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30 | /*----- Header files ------------------------------------------------------*/ |
31 | |
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32 | #include <mLib/sub.h> |
33 | |
34 | |
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35 | #include "mp.h" |
36 | |
37 | /*----- Main code ---------------------------------------------------------*/ |
38 | |
d34decd2 |
39 | /* --- @mp_new@ --- * |
40 | * |
41 | * Arguments: @size_t sz@ = size of vector required |
42 | * @unsigned f@ = flags to set |
43 | * |
44 | * Returns: Pointer to a new MP structure. |
45 | * |
46 | * Use: Allocates a new multiprecision integer. The data space is |
47 | * allocated from either the standard global or secret arena, |
48 | * depending on the initial flags requested. |
49 | */ |
50 | |
51 | mp *mp_new(size_t sz, unsigned f) |
52 | { |
53 | mp *m = CREATE(mp); |
54 | m->a = (f & MP_BURN) ? MPARENA_SECURE : MPARENA_GLOBAL; |
55 | m->v = mpalloc(m->a, sz); |
56 | m->vl = m->v + sz; |
57 | m->sz = sz; |
58 | m->f = f & ~(MP_CONST | MP_DESTROYED); |
59 | m->ref = 1; |
60 | return (m); |
61 | } |
62 | |
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63 | /* --- @mp_create@ --- * |
64 | * |
65 | * Arguments: @size_t sz@ = size of vector required |
66 | * |
67 | * Returns: Pointer to pristine new MP structure with enough memory |
68 | * bolted onto it. |
69 | * |
70 | * Use: Creates a new multiprecision integer, initially zero. The |
71 | * integer has a single reference. |
72 | */ |
73 | |
74 | mp *mp_create(size_t sz) |
75 | { |
76 | mp *m = CREATE(mp); |
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77 | m->v = mpalloc(MPARENA_GLOBAL, sz); |
d3409d5e |
78 | m->vl = m->v + sz; |
79 | m->sz = sz; |
d34decd2 |
80 | m->a = MPARENA_GLOBAL; |
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81 | m->f = MP_UNDEF; |
82 | m->ref = 1; |
83 | return (m); |
84 | } |
85 | |
d34decd2 |
86 | /* --- @mp_createsecure@ --- * |
87 | * |
88 | * Arguments: @size_t sz@ = size of vector required |
89 | * |
90 | * Returns: Pointer to pristine new MP structure with enough memory |
91 | * bolted onto it. |
92 | * |
93 | * Use: Creates a new multiprecision integer with indeterminate |
94 | * contents. The integer has a single reference. The integer's |
95 | * data space is allocated from the secure arena. Its burn flag |
96 | * is set. |
97 | */ |
98 | |
99 | mp *mp_createsecure(size_t sz) |
100 | { |
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101 | mp *m = CREATE(mp); |
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102 | m->v = mpalloc(MPARENA_SECURE, sz); |
103 | m->vl = m->v + sz; |
104 | m->sz = sz; |
105 | m->a = MPARENA_SECURE; |
106 | m->f = MP_UNDEF | MP_BURN; |
107 | m->ref = 1; |
108 | return (m); |
109 | } |
110 | |
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111 | /* --- @mp_build@ --- * |
112 | * |
113 | * Arguments: @mp *m@ = pointer to an MP block to fill in |
114 | * @mpw *v@ = pointer to a word array |
115 | * @mpw *vl@ = pointer just past end of array |
116 | * |
117 | * Returns: --- |
118 | * |
119 | * Use: Creates a multiprecision integer representing some smallish |
120 | * number. You must provide storage for the number and dispose |
121 | * of it when you've finished with it. The number is marked as |
122 | * constant while it exists. |
123 | */ |
124 | |
125 | void mp_build(mp *m, mpw *v, mpw *vl) |
126 | { |
127 | m->v = v; |
128 | m->vl = vl; |
129 | m->sz = vl - v; |
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130 | m->a = MPARENA_GLOBAL; |
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131 | m->f = MP_CONST; |
132 | m->ref = 1; |
133 | } |
134 | |
135 | /* --- @mp_destroy@ --- * |
136 | * |
137 | * Arguments: @mp *m@ = pointer to a multiprecision integer |
138 | * |
139 | * Returns: --- |
140 | * |
141 | * Use: Destroys a multiprecision integer. The reference count isn't |
142 | * checked. Don't use this function if you don't know what |
143 | * you're doing: use @mp_drop@ instead. |
144 | */ |
145 | |
146 | void mp_destroy(mp *m) |
147 | { |
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148 | assert(((void)"Destroying a free integer", !(m->f & MP_DESTROYED))); |
149 | assert(((void)"Attempted to destroy a constant", !(m->f & MP_CONST))); |
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150 | if (m->f & MP_BURN) |
151 | memset(m->v, 0, MPWS(m->sz)); |
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152 | mpfree(m->a, m->v); |
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153 | m->f |= MP_DESTROYED; |
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154 | DESTROY(m); |
155 | } |
156 | |
157 | /* --- @mp_copy@ --- * |
158 | * |
159 | * Arguments: @mp *m@ = pointer to a multiprecision integer |
160 | * |
161 | * Returns: A copy of the given multiprecision integer. |
162 | * |
163 | * Use: Copies the given integer. In fact you just get another |
164 | * reference to the same old one again. |
165 | */ |
166 | |
167 | mp *mp_copy(mp *m) { return MP_COPY(m); } |
168 | |
169 | /* --- @mp_drop@ --- * |
170 | * |
171 | * Arguments: @mp *m@ = pointer to a multiprecision integer |
172 | * |
173 | * Returns: --- |
174 | * |
175 | * Use: Drops a reference to an integer which isn't wanted any more. |
176 | * If there are no more references, the integer is destroyed. |
177 | */ |
178 | |
f1140c41 |
179 | void mp_drop(mp *m) { if (m) MP_DROP(m); } |
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180 | |
181 | /* --- @mp_split@ --- * |
182 | * |
183 | * Arguments: @mp *m@ = pointer to a multiprecision integer |
184 | * |
185 | * Returns: A reference to the same integer, possibly with a different |
186 | * address. |
187 | * |
188 | * Use: Splits off a modifiable version of the integer referred to. |
189 | */ |
190 | |
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191 | mp *mp_split(mp *m) { MP_SPLIT(m); return (m); } |
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192 | |
193 | /* --- @mp_resize@ --- * |
194 | * |
195 | * Arguments: @mp *m@ = pointer to a multiprecision integer |
196 | * @size_t sz@ = new size |
197 | * |
198 | * Returns: --- |
199 | * |
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200 | * Use: Changes an integer's size. The length and value are not |
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201 | * changed. It is an error to |
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202 | */ |
203 | |
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204 | void mp_resize(mp *m, size_t sz) { MP_RESIZE(m, sz); } |
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205 | |
206 | /* --- @mp_ensure@ --- * |
207 | * |
208 | * Arguments: @mp *m@ = pointer to a multiprecision integer |
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209 | * @size_t sz@ = required length |
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210 | * |
211 | * Returns: --- |
212 | * |
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213 | * Use: Changes an integer's length. If there is not enough space |
214 | * allocated for the new length then the size is increased. It |
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215 | */ |
216 | |
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217 | void mp_ensure(mp *m, size_t sz) { MP_ENSURE(m, sz); } |
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218 | |
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219 | /* --- @mp_dest@ --- * |
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220 | * |
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221 | * Arguments: @mp *m@ = a suggested destination integer |
222 | * @size_t sz@ = size required for result, in digits |
223 | * @unsigned f@ = various flags |
224 | * |
225 | * Returns: A pointer to an appropriate destination. |
226 | * |
227 | * Use: Converts a suggested destination into a real destination with |
228 | * the required properties. If the real destination is @d@, |
229 | * then the following properties will hold: |
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230 | * |
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231 | * * @d@ will have exactly one reference. |
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232 | * |
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233 | * * If @m@ is not @MP_NEW@, then the contents of @m@ will not |
234 | * change, unless @f@ has the @MP_UNDEF@ flag set. |
235 | * |
236 | * * If @m@ is not @MP_NEW@, then he reference count of @m@ on |
237 | * entry is equal to the sum of the counts of @d@ and @m@ on |
238 | * exit. |
239 | * |
240 | * * The size of @d@ will be at least @sz@. |
241 | * |
242 | * * If @f@ has the @MP_BURN@ flag set, then @d@ will be |
243 | * allocated from @MPARENA_SECURE@. |
244 | * |
245 | * Understanding this function is crucial to using Catacomb's |
246 | * multiprecision integer library effectively. |
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247 | */ |
248 | |
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249 | mp *mp_dest(mp *m, size_t sz, unsigned f) |
250 | { |
251 | /* --- If no destination, make one --- */ |
252 | |
253 | if (m == MP_NEWSEC) |
254 | m = mp_new(sz, f | MP_UNDEF | MP_BURN); |
255 | else if (m == MP_NEW) |
256 | m = mp_new(sz, f | MP_UNDEF); |
257 | else { |
258 | size_t len = MP_LEN(m); |
259 | unsigned undef = (m->f | f) & MP_UNDEF; |
260 | |
261 | /* --- If the value must be preserved, the block can't shrink --- */ |
262 | |
263 | if (!undef && sz < len) |
264 | sz = len; |
265 | |
266 | /* --- Otherwise check whether the destination is suitable --- */ |
267 | |
268 | if (m->ref > 1 || (m->f & MP_CONST) || |
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269 | sz > m->sz || ((f & ~m->f) & MP_BURN)) { |
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270 | |
271 | /* --- No -- allocate a new buffer --- * |
272 | * |
273 | * The buffer must be secure if (a) the caller requested a secure |
274 | * buffer, or (b) the old buffer is secure and I'm not allowed to |
275 | * discard the old contents. |
276 | */ |
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277 | |
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278 | mparena *a; |
279 | mpw *v; |
280 | |
281 | if ((f & MP_BURN) || (!undef && (m->f & MP_BURN))) |
282 | a = MPARENA_SECURE; |
283 | else |
284 | a = MPARENA_GLOBAL; |
285 | v = mpalloc(a, sz); |
286 | |
287 | /* --- Copy the data over --- */ |
288 | |
289 | if (!undef) { |
290 | memcpy(v, m->v, MPWS(len)); |
291 | if (sz - len > 0) |
292 | memset(v + len, 0, MPWS(sz - len)); |
293 | } |
294 | |
295 | /* --- If @m@ has other references, make a new node --- * |
296 | * |
297 | * Otherwise dispose of the old buffer. |
298 | */ |
299 | |
300 | if (!(m->f & MP_CONST) && m->ref == 1) { |
301 | if (m->f & MP_BURN) |
302 | memset(m->v, 0, MPWS(m->sz)); |
303 | mpfree(m->a, m->v); |
304 | } else { |
305 | mp *mm = CREATE(mp); |
306 | mm->ref = 1; |
307 | mm->f = m->f; |
308 | m->ref--; |
309 | m = mm; |
310 | } |
311 | |
312 | /* --- Fix up the node --- */ |
313 | |
314 | m->v = v; |
315 | m->vl = v + sz; |
316 | m->sz = sz; |
317 | m->f = ((m->f & ~(MP_CONST | MP_BURN)) | |
318 | (f & (MP_BURN | MP_UNDEF))); |
319 | m->a = a; |
320 | } |
321 | |
322 | /* --- If the number is growing in its buffer, fix it up --- */ |
323 | |
324 | else if (sz > len) { |
325 | if (!undef) |
326 | memset(m->vl, 0, MPWS(sz - len)); |
327 | m->vl = m->v + sz; |
328 | } |
329 | } |
330 | |
331 | /* --- Done --- */ |
332 | |
333 | return (m); |
334 | } |
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335 | |
336 | /*----- That's all, folks -------------------------------------------------*/ |