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#include <tommath.h>
#ifdef BN_MP_2EXPT_C
/* LibTomMath, multiple-precision integer library -- Tom St Denis
*
* LibTomMath is a library that provides multiple-precision
* integer arithmetic as well as number theoretic functionality.
*
* The library was designed directly after the MPI library by
* Michael Fromberger but has been written from scratch with
* additional optimizations in place.
*
* The library is free for all purposes without any express
* guarantee it works.
*
* Tom St Denis, tomstdenis@gmail.com, http://libtom.org
*/
/* computes a = 2**b
*
* Simple algorithm which zeroes the int, grows it then just sets one bit
* as required.
*/
int mp_2expt(mp_int * a, int b)
{
int res;
/* zero a as per default */
mp_zero(a);
/* grow a to accomodate the single bit */
if ((res = mp_grow(a, b / DIGIT_BIT + 1)) != MP_OKAY) {
return res;
}
/* set the used count of where the bit will go */
a->used = b / DIGIT_BIT + 1;
/* put the single bit in its place */
a->dp[b / DIGIT_BIT] = ((mp_digit) 1) << (b % DIGIT_BIT);
return MP_OKAY;
}
#endif
/* $Source: /cvs/libtom/libtommath/bn_mp_2expt.c,v $ */
/* $Revision: 1.4 $ */
/* $Date: 2006/12/28 01:25:13 $ */
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