tommath/bn_mp_mod.c
Moritz Lenz 265651b2c7 Fix mp_mod(a, b, c) if b < 0 and a = n * b, n integer
it used to return b, now it return 0.
2012-01-08 20:49:01 +01:00

49 lines
1.0 KiB
C

#include <tommath.h>
#ifdef BN_MP_MOD_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
*/
/* c = a mod b, 0 <= c < b if b > 0, b < c <= 0 if b < 0 */
int
mp_mod (mp_int * a, mp_int * b, mp_int * c)
{
mp_int t;
int res;
if ((res = mp_init (&t)) != MP_OKAY) {
return res;
}
if ((res = mp_div (a, b, NULL, &t)) != MP_OKAY) {
mp_clear (&t);
return res;
}
if (mp_iszero(&t) || t.sign == b->sign) {
res = MP_OKAY;
mp_exch (&t, c);
} else {
res = mp_add (b, &t, c);
}
mp_clear (&t);
return res;
}
#endif
/* $Source$ */
/* $Revision$ */
/* $Date$ */