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#include <tommath.h>
#ifdef BN_MP_REDUCE_2K_SETUP_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@iahu.ca, http://math.libtomcrypt.org
*/
/* determines the setup value */
int
mp_reduce_2k_setup(mp_int *a, mp_digit *d)
{
int res, p;
mp_int tmp;
if ((res = mp_init(&tmp)) != MP_OKAY) {
return res;
}
p = mp_count_bits(a);
if ((res = mp_2expt(&tmp, p)) != MP_OKAY) {
mp_clear(&tmp);
return res;
}
if ((res = s_mp_sub(&tmp, a, &tmp)) != MP_OKAY) {
mp_clear(&tmp);
return res;
}
*d = tmp.dp[0];
mp_clear(&tmp);
return MP_OKAY;
}
#endif
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