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comparison bn_mp_set_int.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 /* set a 32-bit const */
18 int mp_set_int (mp_int * a, unsigned long b)
19 {
20 int x, res;
21
22 mp_zero (a);
23
24 /* set four bits at a time */
25 for (x = 0; x < 8; x++) {
26 /* shift the number up four bits */
27 if ((res = mp_mul_2d (a, 4, a)) != MP_OKAY) {
28 return res;
29 }
30
31 /* OR in the top four bits of the source */
32 a->dp[0] |= (b >> 28) & 15;
33
34 /* shift the source up to the next four bits */
35 b <<= 4;
36
37 /* ensure that digits are not clamped off */
38 a->used += 1;
39 }
40 mp_clamp (a);
41 return MP_OKAY;
42 }