tommath/bn_mp_reduce_2k_setup.c

48 lines
1.1 KiB
C
Raw Normal View History

#include <tommath_private.h>
2004-10-29 18:07:18 -04:00
#ifdef BN_MP_REDUCE_2K_SETUP_C
2003-08-04 21:24:44 -04:00
/* 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, tstdenis82@gmail.com, http://libtom.org
2003-08-04 21:24:44 -04:00
*/
/* determines the setup value */
2017-09-20 10:59:43 -04:00
int mp_reduce_2k_setup(const mp_int *a, mp_digit *d)
2003-08-04 21:24:44 -04:00
{
int res, p;
mp_int tmp;
2017-08-29 23:51:11 -04:00
2003-08-04 21:24:44 -04:00
if ((res = mp_init(&tmp)) != MP_OKAY) {
return res;
}
2017-08-29 23:51:11 -04:00
2003-08-04 21:24:44 -04:00
p = mp_count_bits(a);
if ((res = mp_2expt(&tmp, p)) != MP_OKAY) {
mp_clear(&tmp);
return res;
}
2017-08-29 23:51:11 -04:00
2003-08-04 21:24:44 -04:00
if ((res = s_mp_sub(&tmp, a, &tmp)) != MP_OKAY) {
mp_clear(&tmp);
return res;
}
2017-08-29 23:51:11 -04:00
2003-08-04 21:24:44 -04:00
*d = tmp.dp[0];
mp_clear(&tmp);
return MP_OKAY;
}
2004-10-29 18:07:18 -04:00
#endif
2005-08-01 12:37:28 -04:00
2017-08-28 10:27:26 -04:00
/* ref: $Format:%D$ */
/* git commit: $Format:%H$ */
/* commit time: $Format:%ai$ */