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comparison bn_mp_grow.c @ 1:22d5cf7d4b1a libtommath

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Renaming branch
author Matt Johnston <matt@ucc.asn.au>
date Mon, 31 May 2004 18:23:46 +0000
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-1:000000000000 1:22d5cf7d4b1a
1 /* LibTomMath, multiple-precision integer library -- Tom St Denis
2 *
3 * LibTomMath is a library that provides multiple-precision
4 * integer arithmetic as well as number theoretic functionality.
5 *
6 * The library was designed directly after the MPI library by
7 * Michael Fromberger but has been written from scratch with
8 * additional optimizations in place.
9 *
10 * The library is free for all purposes without any express
11 * guarantee it works.
12 *
13 * Tom St Denis, [email protected], http://math.libtomcrypt.org
14 */
15 #include <tommath.h>
16
17 /* grow as required */
18 int mp_grow (mp_int * a, int size)
19 {
20 int i;
21 mp_digit *tmp;
22
23 /* if the alloc size is smaller alloc more ram */
24 if (a->alloc < size) {
25 /* ensure there are always at least MP_PREC digits extra on top */
26 size += (MP_PREC * 2) - (size % MP_PREC);
27
28 /* reallocate the array a->dp
29 *
30 * We store the return in a temporary variable
31 * in case the operation failed we don't want
32 * to overwrite the dp member of a.
33 */
34 tmp = OPT_CAST(mp_digit) XREALLOC (a->dp, sizeof (mp_digit) * size);
35 if (tmp == NULL) {
36 /* reallocation failed but "a" is still valid [can be freed] */
37 return MP_MEM;
38 }
39
40 /* reallocation succeeded so set a->dp */
41 a->dp = tmp;
42
43 /* zero excess digits */
44 i = a->alloc;
45 a->alloc = size;
46 for (; i < a->alloc; i++) {
47 a->dp[i] = 0;
48 }
49 }
50 return MP_OKAY;
51 }