bn_mp_set_int.c revision 1.2 
1/*	$NetBSD: bn_mp_set_int.c,v 1.2 2017/01/28 21:31:47 christos Exp $	*/
2
3#include <tommath.h>
4#ifdef BN_MP_SET_INT_C
5/* LibTomMath, multiple-precision integer library -- Tom St Denis
6 *
7 * LibTomMath is a library that provides multiple-precision
8 * integer arithmetic as well as number theoretic functionality.
9 *
10 * The library was designed directly after the MPI library by
11 * Michael Fromberger but has been written from scratch with
12 * additional optimizations in place.
13 *
14 * The library is free for all purposes without any express
15 * guarantee it works.
16 *
17 * Tom St Denis, tomstdenis@gmail.com, http://libtom.org
18 */
19
20/* set a 32-bit const */
21int mp_set_int (mp_int * a, unsigned long b)
22{
23  int     x, res;
24
25  mp_zero (a);
26
27  /* set four bits at a time */
28  for (x = 0; x < 8; x++) {
29    /* shift the number up four bits */
30    if ((res = mp_mul_2d (a, 4, a)) != MP_OKAY) {
31      return res;
32    }
33
34    /* OR in the top four bits of the source */
35    a->dp[0] |= (b >> 28) & 15;
36
37    /* shift the source up to the next four bits */
38    b <<= 4;
39
40    /* ensure that digits are not clamped off */
41    a->used += 1;
42  }
43  mp_clamp (a);
44  return MP_OKAY;
45}
46#endif
47
48/* Source: /cvs/libtom/libtommath/bn_mp_set_int.c,v  */
49/* Revision: 1.4  */
50/* Date: 2006/12/28 01:25:13  */
51