tommath/bn_mp_mod_d.c

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2003-02-28 11:08:34 -05:00
/* LibTomMath, multiple-precision integer library -- Tom St Denis
*
* LibTomMath is library that provides for multiple-precision
* integer arithmetic as well as number theoretic functionality.
*
* The library is 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://libtommath.iahu.ca
*/
#include <tommath.h>
int
mp_mod_d (mp_int * a, mp_digit b, mp_digit * c)
{
mp_int t, t2;
int res;
if ((res = mp_init (&t)) != MP_OKAY) {
return res;
}
if ((res = mp_init (&t2)) != MP_OKAY) {
mp_clear (&t);
return res;
}
mp_set (&t, b);
mp_div (a, &t, NULL, &t2);
if (t2.sign == MP_NEG) {
if ((res = mp_add_d (&t2, b, &t2)) != MP_OKAY) {
mp_clear (&t);
mp_clear (&t2);
return res;
}
}
*c = t2.dp[0];
mp_clear (&t);
mp_clear (&t2);
return MP_OKAY;
}