/* -*-c-*-
*
- * $Id: mp-mem.c,v 1.1 1999/11/17 18:02:16 mdw Exp $
+ * $Id: mp-mem.c,v 1.8 2004/04/08 16:17:32 mdw Exp $
*
* Memory management for multiprecision numbers
*
* (c) 1999 Straylight/Edgeware
*/
-/*----- Licensing notice --------------------------------------------------*
+/*----- Licensing notice --------------------------------------------------*
*
* This file is part of Catacomb.
*
* it under the terms of the GNU Library General Public License as
* published by the Free Software Foundation; either version 2 of the
* License, or (at your option) any later version.
- *
+ *
* Catacomb is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU Library General Public License for more details.
- *
+ *
* You should have received a copy of the GNU Library General Public
* License along with Catacomb; if not, write to the Free
* Software Foundation, Inc., 59 Temple Place - Suite 330, Boston,
* MA 02111-1307, USA.
*/
-/*----- Revision history --------------------------------------------------*
- *
- * $Log: mp-mem.c,v $
- * Revision 1.1 1999/11/17 18:02:16 mdw
- * New multiprecision integer arithmetic suite.
- *
- */
-
/*----- Header files ------------------------------------------------------*/
+#include <mLib/sub.h>
+
+
#include "mp.h"
/*----- Main code ---------------------------------------------------------*/
+/* --- @mp_new@ --- *
+ *
+ * Arguments: @size_t sz@ = size of vector required
+ * @unsigned f@ = flags to set
+ *
+ * Returns: Pointer to a new MP structure.
+ *
+ * Use: Allocates a new multiprecision integer. The data space is
+ * allocated from either the standard global or secret arena,
+ * depending on the initial flags requested.
+ */
+
+mp *mp_new(size_t sz, unsigned f)
+{
+ mp *m = CREATE(mp);
+ m->a = (f & MP_BURN) ? MPARENA_SECURE : MPARENA_GLOBAL;
+ m->v = mpalloc(m->a, sz);
+ m->vl = m->v + sz;
+ m->sz = sz;
+ m->f = f & ~(MP_CONST | MP_DESTROYED);
+ m->ref = 1;
+ return (m);
+}
+
/* --- @mp_create@ --- *
*
* Arguments: @size_t sz@ = size of vector required
mp *mp_create(size_t sz)
{
mp *m = CREATE(mp);
- m->v = MP_ALLOC(sz);
+ m->v = mpalloc(MPARENA_GLOBAL, sz);
m->vl = m->v + sz;
m->sz = sz;
+ m->a = MPARENA_GLOBAL;
m->f = MP_UNDEF;
m->ref = 1;
return (m);
}
+/* --- @mp_createsecure@ --- *
+ *
+ * Arguments: @size_t sz@ = size of vector required
+ *
+ * Returns: Pointer to pristine new MP structure with enough memory
+ * bolted onto it.
+ *
+ * Use: Creates a new multiprecision integer with indeterminate
+ * contents. The integer has a single reference. The integer's
+ * data space is allocated from the secure arena. Its burn flag
+ * is set.
+ */
+
+mp *mp_createsecure(size_t sz)
+{
+ mp *m = CREATE(mp);
+ m->v = mpalloc(MPARENA_SECURE, sz);
+ m->vl = m->v + sz;
+ m->sz = sz;
+ m->a = MPARENA_SECURE;
+ m->f = MP_UNDEF | MP_BURN;
+ m->ref = 1;
+ return (m);
+}
+
/* --- @mp_build@ --- *
*
* Arguments: @mp *m@ = pointer to an MP block to fill in
m->v = v;
m->vl = vl;
m->sz = vl - v;
+ m->a = MPARENA_GLOBAL;
m->f = MP_CONST;
m->ref = 1;
}
void mp_destroy(mp *m)
{
- if (m->f & MP_CONST)
- return;
+ assert(((void)"Destroying a free integer", !(m->f & MP_DESTROYED)));
+ assert(((void)"Attempted to destroy a constant", !(m->f & MP_CONST)));
if (m->f & MP_BURN)
memset(m->v, 0, MPWS(m->sz));
- MP_FREE(m->v);
+ mpfree(m->a, m->v);
+ m->f |= MP_DESTROYED;
DESTROY(m);
}
* If there are no more references, the integer is destroyed.
*/
-void mp_drop(mp *m) { MP_DROP(m); }
+void mp_drop(mp *m) { if (m) MP_DROP(m); }
/* --- @mp_split@ --- *
*
*
* Returns: ---
*
- * Use: Resizes the vector containing the integer's digits. The new
- * size must be at least as large as the current integer's
- * length. This isn't really intended for client use.
+ * Use: Changes an integer's size. The length and value are not
+ * changed. It is an error to
*/
void mp_resize(mp *m, size_t sz) { MP_RESIZE(m, sz); }
/* --- @mp_ensure@ --- *
*
* Arguments: @mp *m@ = pointer to a multiprecision integer
- * @size_t sz@ = required size
+ * @size_t sz@ = required length
*
* Returns: ---
*
- * Use: Ensures that the integer has enough space for @sz@ digits.
- * The value is not changed.
+ * Use: Changes an integer's length. If there is not enough space
+ * allocated for the new length then the size is increased. It
*/
void mp_ensure(mp *m, size_t sz) { MP_ENSURE(m, sz); }
-/* --- @mp_modify@ --- *
+/* --- @mp_dest@ --- *
*
- * Arguments: @mp *m@ = pointer to a multiprecision integer
- * @size_t sz@ = size required
+ * Arguments: @mp *m@ = a suggested destination integer
+ * @size_t sz@ = size required for result, in digits
+ * @unsigned f@ = various flags
+ *
+ * Returns: A pointer to an appropriate destination.
+ *
+ * Use: Converts a suggested destination into a real destination with
+ * the required properties. If the real destination is @d@,
+ * then the following properties will hold:
+ *
+ * * @d@ will have exactly one reference.
*
- * Returns: Pointer to the integer (possibly different).
+ * * If @m@ is not @MP_NEW@, then the contents of @m@ will not
+ * change, unless @f@ has the @MP_UNDEF@ flag set.
*
- * Use: Prepares an integer to be overwritten. It's split off from
- * other references to the same integer, and sufficient space is
- * allocated.
+ * * If @m@ is not @MP_NEW@, then he reference count of @m@ on
+ * entry is equal to the sum of the counts of @d@ and @m@ on
+ * exit.
+ *
+ * * The size of @d@ will be at least @sz@.
+ *
+ * * If @f@ has the @MP_BURN@ flag set, then @d@ will be
+ * allocated from @MPARENA_SECURE@.
+ *
+ * Understanding this function is crucial to using Catacomb's
+ * multiprecision integer library effectively.
*/
-mp *mp_modify(mp *m, size_t sz) { MP_MODIFY(m, sz); return (m); }
+mp *mp_dest(mp *m, size_t sz, unsigned f)
+{
+ /* --- If no destination, make one --- */
+
+ if (m == MP_NEWSEC)
+ m = mp_new(sz, f | MP_UNDEF | MP_BURN);
+ else if (m == MP_NEW)
+ m = mp_new(sz, f | MP_UNDEF);
+ else {
+ size_t len = MP_LEN(m);
+ unsigned undef = (m->f | f) & MP_UNDEF;
+
+ /* --- If the value must be preserved, the block can't shrink --- */
+
+ if (!undef && sz < len)
+ sz = len;
+
+ /* --- Otherwise check whether the destination is suitable --- */
+
+ if (m->ref > 1 || (m->f & MP_CONST) ||
+ sz > m->sz || ((f & ~m->f) & MP_BURN)) {
+
+ /* --- No -- allocate a new buffer --- *
+ *
+ * The buffer must be secure if (a) the caller requested a secure
+ * buffer, or (b) the old buffer is secure and I'm not allowed to
+ * discard the old contents.
+ */
+
+ mparena *a;
+ mpw *v;
+
+ if ((f & MP_BURN) || (!undef && (m->f & MP_BURN)))
+ a = MPARENA_SECURE;
+ else
+ a = MPARENA_GLOBAL;
+ v = mpalloc(a, sz);
+
+ /* --- Copy the data over --- */
+
+ if (!undef) {
+ memcpy(v, m->v, MPWS(len));
+ if (sz - len > 0)
+ memset(v + len, 0, MPWS(sz - len));
+ }
+
+ /* --- If @m@ has other references, make a new node --- *
+ *
+ * Otherwise dispose of the old buffer.
+ */
+
+ if (!(m->f & MP_CONST) && m->ref == 1) {
+ if (m->f & MP_BURN)
+ memset(m->v, 0, MPWS(m->sz));
+ mpfree(m->a, m->v);
+ } else {
+ mp *mm = CREATE(mp);
+ mm->ref = 1;
+ mm->f = m->f;
+ m->ref--;
+ m = mm;
+ }
+
+ /* --- Fix up the node --- */
+
+ m->v = v;
+ m->vl = v + sz;
+ m->sz = sz;
+ m->f = ((m->f & ~(MP_CONST | MP_BURN)) |
+ (f & (MP_BURN | MP_UNDEF)));
+ m->a = a;
+ }
+
+ /* --- If the number is growing in its buffer, fix it up --- */
+
+ else if (sz > len) {
+ if (!undef)
+ memset(m->vl, 0, MPWS(sz - len));
+ m->vl = m->v + sz;
+ }
+ }
+
+ /* --- Done --- */
+
+ return (m);
+}
/*----- That's all, folks -------------------------------------------------*/
projects / u / mdw / catacomb / blobdiff