3 * $Id: mp-mem.c,v 1.5 2001/06/16 12:57:00 mdw Exp $
5 * Memory management for multiprecision numbers
7 * (c) 1999 Straylight/Edgeware
10 /*----- Licensing notice --------------------------------------------------*
12 * This file is part of Catacomb.
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.
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.
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,
30 /*----- Revision history --------------------------------------------------*
33 * Revision 1.5 2001/06/16 12:57:00 mdw
34 * Implement some missing functions.
36 * Revision 1.4 2001/02/03 12:00:29 mdw
37 * Now @mp_drop@ checks its argument is non-NULL before attempting to free
38 * it. Note that the macro version @MP_DROP@ doesn't do this.
40 * Revision 1.3 2000/06/17 11:45:09 mdw
41 * Major memory management overhaul. Added arena support. Use the secure
42 * arena for secret integers. Replace and improve the MP management macros
43 * (e.g., replace MP_MODIFY by MP_DEST).
45 * Revision 1.2 1999/12/10 23:19:02 mdw
46 * Improve error-checking.
48 * Revision 1.1 1999/11/17 18:02:16 mdw
49 * New multiprecision integer arithmetic suite.
53 /*----- Header files ------------------------------------------------------*/
60 /*----- Main code ---------------------------------------------------------*/
64 * Arguments: @size_t sz@ = size of vector required
65 * @unsigned f@ = flags to set
67 * Returns: Pointer to a new MP structure.
69 * Use: Allocates a new multiprecision integer. The data space is
70 * allocated from either the standard global or secret arena,
71 * depending on the initial flags requested.
74 mp *mp_new(size_t sz, unsigned f)
77 m->a = (f & MP_BURN) ? MPARENA_SECURE : MPARENA_GLOBAL;
78 m->v = mpalloc(m->a, sz);
81 m->f = f & ~(MP_CONST | MP_DESTROYED);
86 /* --- @mp_create@ --- *
88 * Arguments: @size_t sz@ = size of vector required
90 * Returns: Pointer to pristine new MP structure with enough memory
93 * Use: Creates a new multiprecision integer, initially zero. The
94 * integer has a single reference.
97 mp *mp_create(size_t sz)
100 m->v = mpalloc(MPARENA_GLOBAL, sz);
103 m->a = MPARENA_GLOBAL;
109 /* --- @mp_createsecure@ --- *
111 * Arguments: @size_t sz@ = size of vector required
113 * Returns: Pointer to pristine new MP structure with enough memory
116 * Use: Creates a new multiprecision integer with indeterminate
117 * contents. The integer has a single reference. The integer's
118 * data space is allocated from the secure arena. Its burn flag
122 mp *mp_createsecure(size_t sz)
125 m->v = mpalloc(MPARENA_SECURE, sz);
128 m->a = MPARENA_SECURE;
129 m->f = MP_UNDEF | MP_BURN;
134 /* --- @mp_build@ --- *
136 * Arguments: @mp *m@ = pointer to an MP block to fill in
137 * @mpw *v@ = pointer to a word array
138 * @mpw *vl@ = pointer just past end of array
142 * Use: Creates a multiprecision integer representing some smallish
143 * number. You must provide storage for the number and dispose
144 * of it when you've finished with it. The number is marked as
145 * constant while it exists.
148 void mp_build(mp *m, mpw *v, mpw *vl)
157 /* --- @mp_destroy@ --- *
159 * Arguments: @mp *m@ = pointer to a multiprecision integer
163 * Use: Destroys a multiprecision integer. The reference count isn't
164 * checked. Don't use this function if you don't know what
165 * you're doing: use @mp_drop@ instead.
168 void mp_destroy(mp *m)
170 assert(((void)"Destroying a free integer", !(m->f & MP_DESTROYED)));
171 assert(((void)"Attempted to destroy a constant", !(m->f & MP_CONST)));
173 memset(m->v, 0, MPWS(m->sz));
175 m->f |= MP_DESTROYED;
179 /* --- @mp_copy@ --- *
181 * Arguments: @mp *m@ = pointer to a multiprecision integer
183 * Returns: A copy of the given multiprecision integer.
185 * Use: Copies the given integer. In fact you just get another
186 * reference to the same old one again.
189 mp *mp_copy(mp *m) { return MP_COPY(m); }
191 /* --- @mp_drop@ --- *
193 * Arguments: @mp *m@ = pointer to a multiprecision integer
197 * Use: Drops a reference to an integer which isn't wanted any more.
198 * If there are no more references, the integer is destroyed.
201 void mp_drop(mp *m) { if (m) MP_DROP(m); }
203 /* --- @mp_split@ --- *
205 * Arguments: @mp *m@ = pointer to a multiprecision integer
207 * Returns: A reference to the same integer, possibly with a different
210 * Use: Splits off a modifiable version of the integer referred to.
213 mp *mp_split(mp *m) { MP_SPLIT(m); return (m); }
215 /* --- @mp_resize@ --- *
217 * Arguments: @mp *m@ = pointer to a multiprecision integer
218 * @size_t sz@ = new size
222 * Use: Changes an integer's size. The length and value are not
223 * changed. It is an error to
226 void mp_resize(mp *m, size_t sz) { MP_RESIZE(m, sz); }
228 /* --- @mp_ensure@ --- *
230 * Arguments: @mp *m@ = pointer to a multiprecision integer
231 * @size_t sz@ = required length
235 * Use: Changes an integer's length. If there is not enough space
236 * allocated for the new length then the size is increased. It
239 void mp_ensure(mp *m, size_t sz) { MP_ENSURE(m, sz); }
241 /* --- @mp_dest@ --- *
243 * Arguments: @mp *m@ = a suggested destination integer
244 * @size_t sz@ = size required for result, in digits
245 * @unsigned f@ = various flags
247 * Returns: A pointer to an appropriate destination.
249 * Use: Converts a suggested destination into a real destination with
250 * the required properties. If the real destination is @d@,
251 * then the following properties will hold:
253 * * @d@ will have exactly one reference.
255 * * If @m@ is not @MP_NEW@, then the contents of @m@ will not
256 * change, unless @f@ has the @MP_UNDEF@ flag set.
258 * * If @m@ is not @MP_NEW@, then he reference count of @m@ on
259 * entry is equal to the sum of the counts of @d@ and @m@ on
262 * * The size of @d@ will be at least @sz@.
264 * * If @f@ has the @MP_BURN@ flag set, then @d@ will be
265 * allocated from @MPARENA_SECURE@.
267 * Understanding this function is crucial to using Catacomb's
268 * multiprecision integer library effectively.
271 mp *mp_dest(mp *m, size_t sz, unsigned f)
273 /* --- If no destination, make one --- */
276 m = mp_new(sz, f | MP_UNDEF | MP_BURN);
277 else if (m == MP_NEW)
278 m = mp_new(sz, f | MP_UNDEF);
280 size_t len = MP_LEN(m);
281 unsigned undef = (m->f | f) & MP_UNDEF;
283 /* --- If the value must be preserved, the block can't shrink --- */
285 if (!undef && sz < len)
288 /* --- Otherwise check whether the destination is suitable --- */
290 if (m->ref > 1 || (m->f & MP_CONST) ||
291 m->sz > len || !((f & ~m->f) & MP_BURN)) {
293 /* --- No -- allocate a new buffer --- *
295 * The buffer must be secure if (a) the caller requested a secure
296 * buffer, or (b) the old buffer is secure and I'm not allowed to
297 * discard the old contents.
303 if ((f & MP_BURN) || (!undef && (m->f & MP_BURN)))
309 /* --- Copy the data over --- */
312 memcpy(v, m->v, MPWS(len));
314 memset(v + len, 0, MPWS(sz - len));
317 /* --- If @m@ has other references, make a new node --- *
319 * Otherwise dispose of the old buffer.
322 if (!(m->f & MP_CONST) && m->ref == 1) {
324 memset(m->v, 0, MPWS(m->sz));
334 /* --- Fix up the node --- */
339 m->f = ((m->f & ~(MP_CONST | MP_BURN)) |
340 (f & (MP_BURN | MP_UNDEF)));
344 /* --- If the number is growing in its buffer, fix it up --- */
348 memset(m->vl, 0, MPWS(sz - len));
358 /*----- That's all, folks -------------------------------------------------*/