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comparison bn_mp_read_unsigned_bin.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 /* reads a unsigned char array, assumes the msb is stored first [big endian] */
18 int
19 mp_read_unsigned_bin (mp_int * a, unsigned char *b, int c)
20 {
21 int res;
22
23 /* make sure there are at least two digits */
24 if (a->alloc < 2) {
25 if ((res = mp_grow(a, 2)) != MP_OKAY) {
26 return res;
27 }
28 }
29
30 /* zero the int */
31 mp_zero (a);
32
33 /* read the bytes in */
34 while (c-- > 0) {
35 if ((res = mp_mul_2d (a, 8, a)) != MP_OKAY) {
36 return res;
37 }
38
39 #ifndef MP_8BIT
40 a->dp[0] |= *b++;
41 a->used += 1;
42 #else
43 a->dp[0] = (*b & MP_MASK);
44 a->dp[1] |= ((*b++ >> 7U) & 1);
45 a->used += 2;
46 #endif
47 }
48 mp_clamp (a);
49 return MP_OKAY;
50 }