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#include <tommath_private.h>
#ifdef BN_MP_RAND_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, tstdenis82@gmail.com, http://libtom.org
*/
#if MP_GEN_RANDOM_MAX == 0xffffffff
#define MP_GEN_RANDOM_SHIFT 32
#elif MP_GEN_RANDOM_MAX == 32767
/* SHRT_MAX */
#define MP_GEN_RANDOM_SHIFT 15
#elif MP_GEN_RANDOM_MAX == 2147483647
/* INT_MAX */
#define MP_GEN_RANDOM_SHIFT 31
#elif !defined(MP_GEN_RANDOM_SHIFT)
#error Thou shalt define their own valid MP_GEN_RANDOM_SHIFT
#endif
/* makes a pseudo-random int of a given size */
static mp_digit s_gen_random(void)
{
mp_digit d = 0, msk = 0;
do {
d <<= MP_GEN_RANDOM_SHIFT;
d |= ((mp_digit) MP_GEN_RANDOM());
msk <<= MP_GEN_RANDOM_SHIFT;
msk |= (MP_MASK & MP_GEN_RANDOM_MAX);
} while ((MP_MASK & msk) != MP_MASK);
d &= MP_MASK;
return d;
}
int mp_rand(mp_int *a, int digits)
{
int res;
mp_digit d;
mp_zero(a);
if (digits <= 0) {
return MP_OKAY;
}
/* first place a random non-zero digit */
do {
d = s_gen_random();
} while (d == 0);
if ((res = mp_add_d(a, d, a)) != MP_OKAY) {
return res;
}
while (--digits > 0) {
if ((res = mp_lshd(a, 1)) != MP_OKAY) {
return res;
}
if ((res = mp_add_d(a, s_gen_random(), a)) != MP_OKAY) {
return res;
}
}
return MP_OKAY;
}
#endif
/* ref: $Format:%D$ */
/* git commit: $Format:%H$ */
/* commit time: $Format:%ai$ */
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