1#include <tommath.h>
2#ifdef BN_MP_2EXPT_C
3/* LibTomMath, multiple-precision integer library -- Tom St Denis
4 *
5 * LibTomMath is a library that provides multiple-precision
6 * integer arithmetic as well as number theoretic functionality.
7 *
8 * The library was designed directly after the MPI library by
9 * Michael Fromberger but has been written from scratch with
10 * additional optimizations in place.
11 *
12 * The library is free for all purposes without any express
13 * guarantee it works.
14 *
15 * Tom St Denis, tomstdenis@gmail.com, http://libtom.org
16 */
17
18/* computes a = 2**b
19 *
20 * Simple algorithm which zeroes the int, grows it then just sets one bit
21 * as required.
22 */
23int
24mp_2expt (mp_int * a, int b)
25{
26  int     res;
27
28  /* zero a as per default */
29  mp_zero (a);
30
31  /* grow a to accomodate the single bit */
32  if ((res = mp_grow (a, b / DIGIT_BIT + 1)) != MP_OKAY) {
33    return res;
34  }
35
36  /* set the used count of where the bit will go */
37  a->used = b / DIGIT_BIT + 1;
38
39  /* put the single bit in its place */
40  a->dp[b / DIGIT_BIT] = ((mp_digit)1) << (b % DIGIT_BIT);
41
42  return MP_OKAY;
43}
44#endif
45
46/* $Source: /cvs/libtom/libtommath/bn_mp_2expt.c,v $ */
47/* $Revision: 1.4 $ */
48/* $Date: 2006/12/28 01:25:13 $ */
49