30 lines
852 B
C
30 lines
852 B
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
|
|
*/
|
|
#include <tommath.h>
|
|
|
|
/* pre-calculate the value required for Barrett reduction
|
|
* For a given modulus "b" it calulates the value required in "a"
|
|
*/
|
|
int
|
|
mp_reduce_setup (mp_int * a, mp_int * b)
|
|
{
|
|
int res;
|
|
|
|
if ((res = mp_2expt (a, b->used * 2 * DIGIT_BIT)) != MP_OKAY) {
|
|
return res;
|
|
}
|
|
return mp_div (a, b, a, NULL);
|
|
}
|