1/*	$NetBSD: bn_mp_2expt.c,v 1.1.1.1 2011/04/13 18:14:54 elric Exp $	*/
2
3#include <tommath.h>
4#ifdef BN_MP_2EXPT_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/* computes a = 2**b
21 *
22 * Simple algorithm which zeroes the int, grows it then just sets one bit
23 * as required.
24 */
25int
26mp_2expt (mp_int * a, int b)
27{
28  int     res;
29
30  /* zero a as per default */
31  mp_zero (a);
32
33  /* grow a to accomodate the single bit */
34  if ((res = mp_grow (a, b / DIGIT_BIT + 1)) != MP_OKAY) {
35    return res;
36  }
37
38  /* set the used count of where the bit will go */
39  a->used = b / DIGIT_BIT + 1;
40
41  /* put the single bit in its place */
42  a->dp[b / DIGIT_BIT] = ((mp_digit)1) << (b % DIGIT_BIT);
43
44  return MP_OKAY;
45}
46#endif
47
48/* Source: /cvs/libtom/libtommath/bn_mp_2expt.c,v */
49/* Revision: 1.4 */
50/* Date: 2006/12/28 01:25:13 */
51