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#include "tommath_private.h"
#ifdef BN_MP_2EXPT_C
/* LibTomMath, multiple-precision integer library -- Tom St Denis */
/* SPDX-License-Identifier: Unlicense */
/* computes a = 2**b
*
* Simple algorithm which zeroes the int, grows it then just sets one bit
* as required.
*/
mp_err mp_2expt(mp_int *a, int b)
{
mp_err err;
if (b < 0) {
return MP_VAL;
}
/* zero a as per default */
mp_zero(a);
/* grow a to accomodate the single bit */
if ((err = mp_grow(a, (b / MP_DIGIT_BIT) + 1)) != MP_OKAY) {
return err;
}
/* set the used count of where the bit will go */
a->used = (b / MP_DIGIT_BIT) + 1;
/* put the single bit in its place */
a->dp[b / MP_DIGIT_BIT] = (mp_digit)1 << (mp_digit)(b % MP_DIGIT_BIT);
return MP_OKAY;
}
#endif
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