1/*	$NetBSD: bn_mp_reduce_2k_setup.c,v 1.2 2017/01/28 21:31:47 christos Exp $	*/
2
3#include <tommath.h>
4#ifdef BN_MP_REDUCE_2K_SETUP_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/* determines the setup value */
21int mp_reduce_2k_setup(mp_int *a, mp_digit *d)
22{
23   int res, p;
24   mp_int tmp;
25
26   if ((res = mp_init(&tmp)) != MP_OKAY) {
27      return res;
28   }
29
30   p = mp_count_bits(a);
31   if ((res = mp_2expt(&tmp, p)) != MP_OKAY) {
32      mp_clear(&tmp);
33      return res;
34   }
35
36   if ((res = s_mp_sub(&tmp, a, &tmp)) != MP_OKAY) {
37      mp_clear(&tmp);
38      return res;
39   }
40
41   *d = tmp.dp[0];
42   mp_clear(&tmp);
43   return MP_OKAY;
44}
45#endif
46
47/* Source: /cvs/libtom/libtommath/bn_mp_reduce_2k_setup.c,v  */
48/* Revision: 1.4  */
49/* Date: 2006/12/28 01:25:13  */
50