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comparison libtommath/bn_mp_grow.c @ 284:eed26cff980b

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propagate from branch 'au.asn.ucc.matt.ltm.dropbear' (head 6c790cad5a7fa866ad062cb3a0c279f7ba788583) to branch 'au.asn.ucc.matt.dropbear' (head fff0894a0399405a9410ea1c6d118f342cf2aa64)
author Matt Johnston <matt@ucc.asn.au>
date Wed, 08 Mar 2006 13:23:49 +0000
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children 5ff8218bcee9
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283:bd240aa12ba7 284:eed26cff980b
1 #include <tommath.h>
2 #ifdef BN_MP_GROW_C
3 /* LibTomMath, multiple-precision integer library -- Tom St Denis
4 *
5 * LibTomMath is a library that provides multiple-precision
6 * integer arithmetic as well as number theoretic functionality.
7 *
8 * The library was designed directly after the MPI library by
9 * Michael Fromberger but has been written from scratch with
10 * additional optimizations in place.
11 *
12 * The library is free for all purposes without any express
13 * guarantee it works.
14 *
15 * Tom St Denis, [email protected], http://math.libtomcrypt.org
16 */
17
18 /* grow as required */
19 int mp_grow (mp_int * a, int size)
20 {
21 int i;
22 mp_digit *tmp;
23
24 /* if the alloc size is smaller alloc more ram */
25 if (a->alloc < size) {
26 /* ensure there are always at least MP_PREC digits extra on top */
27 size += (MP_PREC * 2) - (size % MP_PREC);
28
29 /* reallocate the array a->dp
30 *
31 * We store the return in a temporary variable
32 * in case the operation failed we don't want
33 * to overwrite the dp member of a.
34 */
35 tmp = OPT_CAST(mp_digit) XREALLOC (a->dp, sizeof (mp_digit) * size);
36 if (tmp == NULL) {
37 /* reallocation failed but "a" is still valid [can be freed] */
38 return MP_MEM;
39 }
40
41 /* reallocation succeeded so set a->dp */
42 a->dp = tmp;
43
44 /* zero excess digits */
45 i = a->alloc;
46 a->alloc = size;
47 for (; i < a->alloc; i++) {
48 a->dp[i] = 0;
49 }
50 }
51 return MP_OKAY;
52 }
53 #endif