tommath/bn_mp_reduce_is_2k.c

53 lines
1.2 KiB
C
Raw Normal View History

2004-10-29 18:07:18 -04:00
#include <tommath.h>
#ifdef BN_MP_REDUCE_IS_2K_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 if mp_reduce_2k can be used */
2003-12-24 13:59:22 -05:00
int mp_reduce_is_2k(mp_int *a)
2003-08-04 21:24:44 -04:00
{
2004-08-09 18:15:59 -04:00
int ix, iy, iw;
mp_digit iz;
2003-08-04 21:24:44 -04:00
if (a->used == 0) {
2005-02-12 03:40:15 -05:00
return MP_NO;
2003-08-04 21:24:44 -04:00
} else if (a->used == 1) {
2005-02-12 03:40:15 -05:00
return MP_YES;
2003-08-04 21:24:44 -04:00
} else if (a->used > 1) {
iy = mp_count_bits(a);
2003-12-24 13:59:22 -05:00
iz = 1;
iw = 1;
/* Test every bit from the second digit up, must be 1 */
2003-08-04 21:24:44 -04:00
for (ix = DIGIT_BIT; ix < iy; ix++) {
2003-12-24 13:59:22 -05:00
if ((a->dp[iw] & iz) == 0) {
2005-02-12 03:40:15 -05:00
return MP_NO;
2003-08-04 21:24:44 -04:00
}
2003-12-24 13:59:22 -05:00
iz <<= 1;
2004-08-09 18:15:59 -04:00
if (iz > (mp_digit)MP_MASK) {
2003-12-24 13:59:22 -05:00
++iw;
iz = 1;
}
2003-08-04 21:24:44 -04:00
}
}
2005-02-12 03:40:15 -05:00
return MP_YES;
2003-08-04 21:24:44 -04:00
}
2004-10-29 18:07:18 -04:00
#endif
2005-08-01 12:37:28 -04:00
/* $Source$ */
/* $Revision$ */
/* $Date$ */